basic copier

Basic copier for Service Master��

Ricoh Europe B.V.Technical Training Centre www.get-u-wice.com1

Basic copier for Service Master

Last Modified: 10/07/2001

Ricoh Europe B.V.Technical Training Centre www.get-u-wice.co m

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Short Description� This basic copier module is the starting point for

a new employee, to start his career as a service technician. The module contains the basic technologies that used in the copy process for analog and digital copiers.



Objectives� After completion of this training a serv ice technician:

� Is familiar with the user feature s of a copier� Understand the copiers jargon/terminology� Ha s a good understanding about the basic technologies of

a copier� Can do installation, including options� can print a SMC sheet� can determine the firmware version� can do a firmware upgrade� Can do maintenance� Can do troubleshooting� Can do adjustments� Can report to the product specialist� Knows how to u se a Service Manual� Can follow product training for engines



Course Overview1. Copy paper2. Copier3. User Training4. Options / Installation5. Advanced copier technology6. Service7. Information Flow 8. Specifications

This training module tells about the copy process. First, it is important to know what a user can do with a copier. After this, the module gives an answer on what happens inside that copy machine. From scanning the original, it says how the toner particles come onto the right location on the copy and why the toner sticks to the paper. What is the difference between an analog and a digital copier? It also describes the paper path trough the machine.Besides knowing how the copier works, the engineer must know what to do at the customers. With help of some tools and manuals, he must be able to keep the copier running, with good copy quality. Copiers need maintenance after a periodic number of copies, just like cars after some kilometers. If the copy quality is bad, you might adjust the machine. If the machine is broken, you might repair it.



Requirements� Computer based training:

� Windows PC Or � Macintosh

� Hands on:� Digital black and white copier, ADF/ARDF,

Finisher� Training materials

Computer based training:� Windows PC:� Intel 486 processor, minimum 66 MHz (Intel Pentium-processor recommended)� Windows 95/98/NT� Double-speed CD ROM or better� Minimum 16 Mb of free RAM� Color display recommended� Soundcard recommended

� Macintosh:� Power Macintosh recommended� Mac OS 7.6 or higher (previous Mac OS needs the thread manager)� Double speed CD ROM or better � Minimum 16 Mb of free RAM� Color display recommended

Hands on:Later in this training module we need this requirements to do some exercises.The exercises in this module are generated for a generic copier with ADF and finisher.However it is possible that not all exercises can be done on all machine’s, because some functions are not available, in that case skip that part of the exercise.



Pre-requisites� Basic electronic skills



Training Materials� Main Document

� Maincopier.ppt� Downloads

� Basiccopier.exe� CBT� Operating Instructions

Main Document� Maincopier.ppt

� PowerPoint presentation with notes pages of the main documentDownloads

� Basiccopier.exe� Self extractable pdf file containing:

�main document notes pages�core technology manual pages for basic copier�Exercises

CBT� Copier technology Technical Training Tool (Basic copier CBT)



Exam� Yes, WICE Multiple choice exam

Name of the exam: Basic copier exam



1. Copy paper� Study the Copy Pa per section of the Copier Computer

Based Training CD.

1. Copy Pap er

Study the Copy Paper section of the Copier Computer Based Training CD.Make sure that you understand:

� Paper sizes� Paper weight� Paper gain� Paper curl� Front and back sides of paper



2. Copier� Study the Copier section of the Copier Computer Based

Training CD.

2. Copier

Study the Copier section of the Copier Computer Based Training CD.Make sure that you first have to start with the analogue copier and that you understand:

� Copy process overview� A closer look

� Scanning�Scanning�Absorbing�Exposure to photoconductor�Lens�Enlargement�Reduction

� Photoconductor�Types�Layers

� Toner on latent image�Charge�Exposure�Development�Transfer�Separation�Cleaning�Quenching

� Transfer to paper�Friction�FRR�Registration

� Fusing



After you finished the analogue copier continue with the digital copier and make sure that you understand:

� Scanning� Shading

� White shading� Black level correction

� Laser exposure� Development



3. User Training

3. User Training



User Training Content� Introduction� Operation panel� User tools� Basic functions� Other functions

3. User Training



Introduction� All functions and features on copiers can be

used to change the output� For example the original’s are simplex but the

output is duplex with a staple.

3. User Training

This part of the module will explain most common used functions and features on copiers.



Different Levels� Normal� User tools� Service mode

3. User Training

NormalEvery user can use the machine for copyingUser toolsIn the user tools items can be changed for example date and time.In the user tools there is a special function called key operator tools, this is a kind of administration tool. A password can be programmed that not all users can access the key operator user tools.Service modeThe service mode is for the technician.



Scanning� The original can be placed on the platen glass or

ADF (automatic document feeder)� With an ARDF (automatic reverse document

feeder) scanning can be done on both side’s of the original

3. User Training

The ADF can hold a lot of documents to scan it all together.The number of documents that can be put in the ADF depends on the copier model.



Imaging� The image process can be changed

� Image density� Enlarge / reduce� Photo mode / text mode� Positive / negative� Image repeat (more image’s on one sheet)� Poster mode

3. User Training

After the scanning process the images are stored in memory and can be processed with the settings (see above) selected by the user.All these processes are done on a digital way.



Paper Selection� Input selection

� Paper size� Which tray� Orientation

� Output selection� Which output bin

3. User Training

Paper sizeOn the operation panel you can be defined which paper tray will be used for the copy job.If a paper tray is filled with A3 sized paper and an other tray is filled with A4 sized paper, we can make a selection which paper size can be used.Which trayAll tray’s can be selected.In case of thick paper or an other size the bypass tray can be used.The bypass is not meant for large amount of paper. OrientationThe A4 size paper can be stored in 2 way’s LEF (long edge feed) and SEF (short edge feed).If the paper tray’s are filled with A4 LEF and with A4 SEF, the selection for orientation can be made.Output selectionIf there are more output bins there can be a selection for which one.



Function Select� Number of copies� Simplex / Duplex� Booklet / Magazine

Simplex Duplex Booklet/Magazine

3. User Training

When starting a copy job we can select the number of copies. Simplex or duplex is done by putting the right image on the front side or the front and back side of the paper.Booklet or magazine is a combination of 4 images on one sheet of paper.



� Punch� Staple� Sort� Stack

Staple Punch

Sorting stacking

Finisher options

321321321

3. User Training

To select punch or staple the option should be installed in the finisher.SortSorting will create a number of sets start from the first to the last page on the same way as your originals.When staple is selected sort is also selected automatically.StackStacking will make it easier to separate the copied sets.



Key Layout

� Example of a n opera tion panel.

� Each button will be explained at the following slides

3. User Training

Each model has it’s own operation panel layout however the symbols that are used are the same.The way of selecting a function can be different, in that case see your operating instruction for your machine.



Screen Contrast

�

� Screen adjust knob

3. User Training

To adjust the screen for a good clear view turn this knob.



Indicators

� Indicators shows errors or s tatus

3. User Training

These indicators can be different on a other copier models.These indicators will show you the following: (starting from the top left)

� Staples empty, Toner empty, Paper empty� Maintenance needed, cover not closed, Paper jam� Communicating (not used for standard copier)� Receiving a file (not used for standard copier)



User Tools/Counter

� User tools / counter key

3. User Training

Two functions for this button.To access the user tools and to access the counter (how many copies are made).



Functions

� Copy mode� Document server mode � Facsimile mode� Printer mode� Scanner mode

3. User Training

At this moment we are only discussing a standard copier.For a lot of copiers there are option’s available for example a fax option.By selecting one of these buttons, the selection for that option can be made.



Display

� Used for input and output.

3. User Training

This is an example of a display.The display is used for output and input.Input

� All selection can be made by touching the right items on the screen.Output

� All information will be displayed, like settings, errors etc.



More Buttons

� Check Modes Energy Saver� Program� Clear modes Interrupt

3. User Training

Check Modes Key� Press to check the entered copy job settings.

Program Key� Press to select the program mode.

Clear Modes Key� Press to clear all selected copy job settings.

Energy Saver Key� Press to switch to and from Energy Saver Mode.

Interrupt Key� Press to make interrupt copies during a copy run.



Power

� Main Power Indicator

� On Indicator

� Operation Switch

3. User Training

Main Power IndicatorIndicates if the main power is turned on.If a printer or a fax option is installed, the main power should never be switched off.For example the machine Main power switch is off and someone is sending you a fax message, the fax won’t be received because the machine is switch off.On Indicator The on indicator will be lit if the machine is switched on for operation.If the indicator is blinking it means that the machine is doing something for example reading/writing the hard disk.If this indicator is blinking never touch the main power switch, because it can damage your machine.Operation switchThis switch is used the switch off and on the machine.If the machine is switched off it still can be used for printing and receive fax messages.



Number Keys

� Number ke ys

3. User Training

Number KeysWith the number keys you can enter the number of copies required.In case of a Multifunctional product they are also used to enter the numbers for faxing.



Start / Stop / Sample

� Sample Copy

� Start

�

� Clear / Stop

3. User Training

Sample copy buttonUsed to see if the output is correct.If the sample copy is approved the keypad can be used to set the number of copies.Start buttonPressing the start button it will start your copy job.Clear / Stop buttonClear to delete a entered numberStop to stop a copy process in progress



Exercise

Do the exercise user functions

3. User Training



User Tools� User Tools

� special settings can be done.� System settings

� Timer settings� Key operator tools

� Copier settings� Density� Margin’s

3. User Training

User toolsFrom the first screen a selection can be made for system settings, copier settings, printer settings, scanner settings and counter. System settingsIn the system settings a lot of items can be changed that are related to the system for example date and time.The key operator tool can be accessed from the system settings.For example to change user code’s.The key operator tool can be password protected.Copier settingsAll items that are related to the copier process can be changed here.For example density and margin’s



4. Options / Installation

4. Options/Installation



Options� Examples

� Finisher� Paper bank� Duplex unit� Interfaces� Mailbox� Other


Each device can have options installed. Details about what options can be installed and it’s functions are explained in the Operating Instructions coming with the device.

Setup Guide� Provides information about setting up the device and its options. This manual is

provided as a printed manual, and also as a PDF file on the CD-ROM labelled "Operating Instructions".



Installation� The installation procedure is described in the

Service Manual


RequirementsThe installation chapter starts with requirements like:

� Environment� Machine level� Minimum space� Power

OptionsIn case of installing options there could be a logical order.Some times you will find a installation flow chart for this order.



5. Advanced Copier Technology

5. Advan ced Copier Technology



Core Technology Manual� Core Tec hnology Manual

topics

� Serv ice Manual CD’s


For several topics in this advanced copier technology chapter there will be referred to the Core Technology Manual (CTM).The CTM can be found on the Service Manual CD ROM’s.



Advanced copier technology content� 5.1 Handling paper� 5.2 Photocopying processes� 5.3 Digital processes� 5.4 Process control� 5.5 Standard Components




5.1 Handling paper� Paper feed� Paper feed methods� Paper tray� By pass� Paper size detection� Paper end detection� Registration� Paper transport� Duplex� Misfeed detection

5.1 Advanced Copier T echnology > Handling Paper

Study the CTM > Handling paper and make sure that you understand:� Paper feed� Paper feed methods� Paper tray� By pass� Paper size detection� Paper end detection� Registration� Paper transport� Duplex� Misfeed detection



Paper feed� Paper feed is the separation of a single sheet of

paper from a paper source—usually a stack of paper in a cassette or tray—and moving it into the machine.


CTM > Handling Paper > Paper Feed

There are several key factors involved with handling paper in office machines (copiers, printers, faxes, whatever). First, there has to be a stock of paper from which to feed, which implies some kind of holder—a tray, a cassette, or a roll—which positions the paper properly for feeding. Second, there has to be a method of separating a single sheet from the source; this is referred to as paper feed. Finally, most machines use sensors to detect paper size and detect the presence or absence of paper.After paper is fed into a machine, it must be transported to a registration mechanism, then to an imaging section where the image is transferred to the paper. Finally the paper passes through an image fusing section and exits the machine.



Paper feed methods� Feed and Rev erse Roller

(FRR)

� Friction Pad

Pick-up rollerFeed roller

Reverse roller

Friction pad

Feed roller



Feed and Reverse Roller (FRR)� The FRR feed mechanism consists of a pick-up roller, a feed roller, and a

reverse roller.Friction Pad

� The friction pad mechanism has two principle components—the paper feed roller and a friction pad.

CBT reference > Copier > Analogue copier > A closer look > Transfer to paper



Paper tray� A paper tray is a non-removable drawer or bin

that is permanently built into or attached to the machine.

500 _she et_t ray .tif 170 0_sh eet _tr ay.tif



Paper TrayA paper tray is a non-removable drawer or bin that is permanently built into or attached to the machine. The capacity of paper trays varies considerably; smaller trays typically hold 250 to 500 sheets of paper, but large capacity trays hold a paper stock of 1000 or more sheets.



By pass� odd paper sizes

� stiff feed stock such as post cards or OHP transpare ncies



By-pass Feed TrayMost copiers and multifunction machines incorporate a fold-out by-pass feed table. By-pass feed is useful for casual copying on odd paper sizes. Also, on most machines, the by-pass feed tray provides a straight paper path that is suitable for stiff feed stock such as post cards or OHP transparencies.



Paper size detection� Switch Combina tion

� Paper Size Dial



For many copy processes, operation timing depends on paper size. Machines can detect paper size in a number of different ways. Here are some common ones.

� Switch Combination� The illustration at the top right shows a paper size detection mechanism

commonly used with cassettes and smaller paper trays.� Paper Size Dial

� Some paper trays use a dial to change paper size (bottom right).



Paper end detection� typical paper end

detection mecha nism for a small paper tra y Paper End Feeler Paper End Sensor

Cutout Lever



The illustration to the right shows a typical paper end detection mechanism for a small paper tray. When the paper tray runs out of paper, the paper end feeler drops into the cutout in the tray bottom plate, and the paper end actuator activates the paper end sensor.The paper end actuator is in contact with a lever. When the tray is drawn out, the lever turns as shown by the arrow and pushes up the actuator. As a result, the feeler rotates upwards. This mechanism prevents the feeler from getting damaged by the paper tray body.



Registration� Registra tion Using A

Stopper

� Registra tion Using Rollers



There is often some slippage during paper feed. As a result, paper cannot be transported directly to the image transfer or printing position, because the image position on the paper would not be stable. After paper feed starts, its transport timing requires adjustment to match it with the imaging process timing. This alignment is called “image registration” or just “registration”. Generally the registration process also removes any skew that the paper may have acquired during paper feed.Here are some common ones.

� Registration Using A Stopper� Some machines use a stopper to delay the paper at the registration rollers.

It allows a simplified drive mechanism where the registration rollers are not stopped during feeding. This method is used mainly with low speed machines.

� Registration Using Rollers� Most copiers and printers use registration rollers to match the paper timing

to the image and remove skew.

CBT reference > Copier > Analogue copier > A closer look > Transfer to paper



Paper transport� Roller Tra nsport

� Belt + Vacuum Tra nsport



Roller TransportThe illustration to the right shows a typical vertical transport mechanism that is used in several models.Belt + Vacuum TransportMany photocopiers use a combination of belts and vacuum fans to transport paper from the drum to the fusing unit. The vacuum holds the paper firmly against the transport belts. This method has the advantage of holding the paper secure to prevent vibrations or slippage that might disturb the as yet unfused toner image.



Duplex� Single sheet

� Stack



Mechanism in a Photocopier that allows the machine to feed a sheet of paper twice through the machine to enable automatic duplex copying.

Duplexing mechanisms can take many forms. However, they have the following things in common.

� They all have some way of sending copies or prints to the duplex mechanism. This is usually accomplished by a “junction gate”, which redirects the paper as it exits from the fusing unit.

� There is a mechanism that turns the paper over (reverses it) so that it is ready to receive an image on the reverse side. This can occur before the paper enters the duplex tray or after it exits the duplex tray.

Duplexing systems in most machines also have the following mechanisms.� There is a tray to hold the sheets of paper to be duplexed. Usually, it is simply

"called the “duplex tray”.� There is a mechanism, usually called a jogger, to align the sheets of paper in the

duplex tray.� There is a paper feed mechanism employing one of the standard paper

separation techniques.Conclusion:There is are 2 different duplexing methods.First one is stack, where paper is gathered in a tray and fed back into the machine in reverse position.Second one is single sheet duplex (interleave duplexing), where paper is not gathered but directly reversed in a tray and fed back into the machine.Next slide will give you an example of the interleave duplexing.



Interleave Duplexing

� Memory needed

� Productiv ity increased

� Decrease wear on originals



Some digital machines have a lot of RAM and a large capacity hard disk that can store many pages. This allows a different method of Duplexing called “interleave Duplexing”, in which sheets are not stacked. Instead, in interleave Duplexing, sheets are continuously fed through the machine and the correct image is selected from memory or disk depending on which sheet and side is in the imaging section.This type of mechanism allows more than one page to be processed at once, and itincreases the productivity of duplex imaging, especially when making multiple duplex copies. Also, in the case of making copies from paper originals, it decreases the cycling of and the wear on originals.

The example shows a 14-page copy. The large numbers in the illustration show the order of pages. The small numbers in circles show the order of sheets of copy paper (if shaded, this indicates the second side).



Misfeed detection� photo interrupters

� unaffected by the reflectivity or transpa rency

LED

Phototransistor

Paper



Misfeed DetectionOffice machines that print images on paper (copiers, fax, laser printers, etc.) have to detect paper Misfeed and jams and take appropriate action. One or more sensors placed along the paper path accomplish Misfeed detection. Typically, photo interrupters with feeler actuators are used for Misfeed detection because they are unaffected by the reflectivity or transparency of the feed stock.The number of Misfeed detectors used depends on the length and complexity of the paper path



5.2 Photocopying processes� Charge� Exposure� Development� Image Transfer And Paper Separation� Cleaning� Quenching� Fusing

5.2 Advanced Copier T echnology > Photocopying Processes

Study the CTM > Photocopying processes and make sure that you understand:� Charge� Exposure� Development� Image Transfer And Paper Separation� Cleaning� Quenching� Fusing

1. CBT reference > Copier > Analogue copier > A closer look > Toner on Latent Image2. CBT reference > Copier > Digital copier



Overview1. Charge

2. Exposure

3. Dev elopment

4. Image Trans fer And Paper Separation

5. Cleaning

6. Quenching

7. Fusing

1 2

3

4

5

6

7Fusing section


CTM > Photocopying Processes

In this slide you can see an overview of the process around the drum.



Charge� Corona Charge

� Charge Roller Method


CTM > Photocopying Processes > Charge

Charge refers to the application of a uniform electrostatic charge to a photoconductor in darkness. At present, two kinds of electrostatic charge methods are widely used.The most common is the corona electrostatic charge method (non-contact type), which takes advantage of the corona discharge produced when a high voltage is applied to a fine wire. The other is the electrostatic charge roller method (contact type), which provides an electrostatic charge by applying a high voltage to a roller and contacting the roller to the photoconductor.



Exposure� Analog Machines

� Digital Machines


CTM > Photocopying Processes > Exposure

Exposure refers to a process where light is applied to a photoconductor to create a latent reverse image on in the form of a charge pattern on the surface of the photoconductive material. Depending on the brightness of the image, the electric potential on the photoconductor's surface is attenuated; thus, forming an electrostatic latent imageIn general you can say that we use three main exposure methods

� flash exposure� strip exposure (sometimes called slit exposure)� laser exposure (covered in the Digital Processes chapter)

Analog MachinesAn exposure lamp illuminates the original. Mirrors reflect light from the original directly onto the photoconductor. This light writes a latent image on the photoconductor. This image is then developed with toner and transferred to the copy paper.

Digital MachinesThe big difference with scanners in digital machines is that the light reflected from the original does not pass directly to the photoconductor.The light is reflected onto a light-sensitive element, such as a CCD (Charge Coupled Device). This device converts the light into an analog electrical signal. Circuits inside the machine convert this signal into a digital signal. This signal then passes to a laser diode, which emits a laser beam to write a latent image on the photoconductor.So, in a digital machine, there is a lot of electronics between the light reflected off the original and the light arriving at the photoconductor.



Development� dual-component development method� single-component development method


CTM > Photocopying Processes > DevelopmentDevelopment systems are divided into:

� dual-component development method� single-component development method (mono-component)

Dual-componentThe two-component development process uses developer made of mixed toner and carrier. These two components rub against each other in the development unit and take on opposite charges. The charged latent image areas of the drum attract the charged toner particles.Advantages

� Achieves high speed development� Allows relatively wide scope in terms of accuracy

Disadvantages� The development section is complex and large� Deterioration of developer over time (difficult to achieve maintenance free

operations)� Requires toner concentration control

Mono-componentThe mono-component development process uses toner only (no carrier). Mono-component development systems are used mainly in small photocopiers with a low copy rate.Advantages:

� Development unit structure is simple and compact.� Toner density control is unnecessary.

Disadvantages:� Unsuitable for high speed developing� Suitable for low-volume copying only because the development unit parts wear

out relatively quickly.



Image Transfer And Paper SeparationA. Pre-trans fer

B. Image Trans fer

C. Paper Separation


CTM > Photocopying Processes > Image Transfer & Paper Separation

The transfer and separation process can be broken down into three areas:Pre-transferJust before the image transfer process starts, guides direct the paper against the photosensitive surface of the drum (or belt). The mechanism is structured so that the transfer charge does not reach this area, and therefore, the paper can achieve complete contact with the photoconductor before image transfer starts.Image TransferThis is the area where the image is actually transferred from the photoconductor to the paper. Generally, an electrostatic charge is applied to the back of the paper to pull the oppositely charged toner from the photoconductor to the paper.Paper SeparationThe paper separates from the photoconductor after the toner image is transferred. This is usually achieved by applying an ac corona to the back of the paper to eliminate the previously applied transfer charge. Pick-off pawls are also used to physically separate paper of low stiffness from the drum.



Cleaning� Cleaning blades

� Cleaning brushes

Counter Blade

Cleaning Brush


CTM > Photocopying Processes > Cleaning

Cleaning refers to the process of removing any toner remaining on the photoconductor (drum or OPC belt) after the imaging process is complete to prepare the photoconductor for the next copy/print cycle. The cleaning step also removes any paper dust on the photoconductor surface.Cleaning is necessary before a new copy cycle or print cycle can start. If the cleaning step were not included in the copy process, the background of images would become progressively darker and dirtier.All cleaning systems use a cleaning blade or a cleaning brush or both. Additionally, all cleaning systems have a mechanism for collecting and storing (or recycling) the collected toner.The most common cleaning systems use blades, and these are further divided into trailing-blade cleaning and counter-blade cleaning systems.Cleaning brushes all rotate in contact with the photoconductor. There are also two types of cleaning brushes—fiber brushes and magnetic brushes.Some cleaning systems also use a corona (pre-cleaning corona) to prepare the drum and toner for cleaning.



Quenching� eliminates any residual

electric charge remaining on the photoconductor after the cleaning process


CTM > Photocopying Processes > Quenching

Quenching is the process that eliminates any residual electric charge remaining on the photoconductor after the cleaning process. Quenching prepares the photoconductor for the charge step of the next copy or print cycle.

Several different methods are used to quench the photoconductor. The most common method is photo quenching using a lamp. Some machines use a combination of a dc corona and photo quenching. A few machines use an ac corona for quenching. The choice of quenching method depends on the type of photoconductor used and the details of the other steps of the copy process.



Fusing� Hot roller

� Pressure roller

� Fusing lamp

� Stripper pawls

Pressure RollerHot Roller

Stripper Pawls

Fusing lamp


CTM > Photocopying Processes > Fusing

After the image transfer and paper separation steps, the image must be bound or “fixed”to the paper. Modern photocopiers and other machines (fax, printer) that use photocopier imaging processes, use resin based toners. To form a stable permanent image, the toner is heated to cause it to melt and soften. Simultaneously, pressure is applied to cause the toner to fuse with the fibers of the paper.



5.3 Digital processes� Digital scanning� Image processing

� Scanner gamma correction� Photo mode smoothing� Moiré� Grayscale processing� Binary picture processing� Image rotation

� Printing

5.3 Advanced Copier T echnology > Digital Processes

Study the CTM > Digital Processes and make sure that you understand:� Digital scanning� Image processing

� Scanner gamma correction� Photo mode smoothing� Magnification and Reduction� Moiré� Grayscale processing� Binary picture processing� Image rotation

� Printing

CBT reference > Copier > Digital copier



Digital Scanning� Analog Machines

� Digital Machines


CTM > Digital Processes > Digital ScanningEarlier in this module we already explained the difference between the analog and digital scanner.

Analog MachinesAn exposure lamp illuminates the original. Mirrors reflect light from the original directly onto the photoconductor. This light writes a latent image on the photoconductor. This image is then developed with toner and transferred to the copy paper.

Digital MachinesThe big difference with scanners in digital machines is that the light reflected from the original does not pass directly to the photoconductor.The light is reflected onto a light-sensitive element, such as a CCD (Charge Coupled Device). This device converts the light into an analog electrical signal. Circuits inside the machine convert this signal into a digital signal. This signal then passes to a laser diode, which emits a laser beam to write a latent image on the photoconductor.So, in a digital machine, there is a lot of electronics between the light reflected off the original and the light arriving at the photoconductor.



Image processing


Image processing describes how digital machines convert the image from a scanned original into digital data. Image processing use techniques for processing the digital data, so that the printout is as close to the original as possible. For example, techniques used to process a business letter will be different from those used to process an original containing photographs.Each model implements these techniques in different ways, and some models do not implement all the techniques. The techniques used by black-and-white machines and color machines are different, but these kind of details will be explained in the product trainings.

The CTM will explain all of the techniques in detail.For this training module we only discuss some of them.



Scanner gamma correction� relationship be tween

original ima ge density a nd analog circui t output should be linear as shown in the upper diagram. Howev er, in reality, it is more like that s hown in the lower diagram.


Scanner Gamma CorrectionScanner gamma correction corrects the data to compensate for the characteristics of the scanner (e.g., CCD response, scanner optics). This ensures that the various shades in the gray scale from black to white on the copy match those on the original.The relationship between original image density and analog circuit output should be linear as shown in the upper diagram. However, in reality, it is more like that shown in the lower diagram.Gamma correction corrects the data for this deviation, as shown by the arrows in the lower diagram.In some machines, the gamma curve can be changed with a service mode.Also, some machines automatically adjust the gamma curve depending on the image density setting selected by the user.



Photo mode smoothing� To make a softer image

Text Mode

Photo Mode


Photo mode smoothingThere are some different processes that use the name 'smoothing'. Photo mode is to make a softer image. Smoothing smoothes the contrast between adjacent pixels, giving better reproduction for photos. Because of this, it will not normally be used in text mode.



Moiré

� The moiré pattern typically appears when the CCD pixel density is a mul tiple of the density of the regular lines on the original.


MoiréWhen one pattern is imposed over another sometimes they interfere with each other and form a third pattern called a moiré pattern. In our products, MTF processing is a major cause of moiré patterns.The photos show the result of moiré.The moiré pattern typically appears when the CCD pixel density is a multiple of the density of the regular lines on the original.



Grayscale processing� Grayscale processing

uses many shades for instance 64 or 256.

64 Grayscales 256 Grayscal es


Grayscale ProcessingThe human eye can discern up to about 200 different levels, or shades, of gray. A lot of digital copiers can create 256 gray levels: 0 through 255. Compare the right and left halves of the images, to see the difference if you have more grayscales available.Grayscale processing uses many shades of gray to reproduce continuous tone originals, such as those containing photographs. A black and white photograph contains an unlimited number of shades of gray, but digital copiers and printers can normally only output a few shades, normally 64 or 256. If grayscale processing is used, the result is a multi-bit per pixel stream of digital data. For example, if there are 256 shades of gray, there are eight bits per pixel.

Note that grayscale processing needs a lot of memory. At eight bits per pixel (256 shades of gray), an A4 or LT page needs about 14 megabytes, without compression.

2550

1111111100000000



Binary picture processing� One bit output

� White or� Black


Binary Picture ProcessingIn binary picture processing, the output data is one-bit only. There are no shades of gray. the output is black or white only.The multi-bit per pixel data stream has to be reduced to single-bit data. To do this, a threshold level is used. If a pixel has a value that is brighter than the threshold, it becomes a white pixel. If it is darker than the threshold, it becomes a black pixel.The threshold can usually be adjusted, and it often varies depending on modes selected at the operation panel. The example on the slide shows how the threshold level affects the output.



Image rotation


Image RotationIf the machine has paper of the same size as the original but different orientation, the image will be rotated by 90 degrees in memory before printing. The machine must have enough working memory to do this. The amount of memory required for a certain paper size depends on the image resolution and the number of bits per pixel.



Printing


CTM > Digital Processes > Printing



The Latent Image� The diagram shows the

typical optical components of a laser printer


CTM > Digital Processes > PrintingCBT reference > Copier > Digital copier > Laser Exposure

The Latent ImageExposure of the photoconductor to the laser beam creates the latent image. A rotating mirror moves the laser beam across the photoconductor to make the main scan while photoconductor rotation controls the sub-scan.

The diagram shows the typical optical components of a laser printer.A: Laser Diode Unit B: F theta LensesC: BTL (Barrel Toroidal Lens)D: Drum MirrorE: Laser Synchronization Detector Board-2F: Laser Synchronization Detector Board-1G: Polygon Mirror MotorH: Cylindrical LensI: OPC DrumJ: Toner Shield Glass



5.4 Process control� Basic concepts� OPC digital systems

5.4 Advanced Copier T echnology > Process Control

Study the CTM > Process Control and make sure that you understand:� Basic concepts� OPC analog systems� OPC digital systems

OPC analog systems is not explained in this module, but is necessary as basic knowledge to understand process control.



Basic Concepts� In this section we will take an overall look at

process control.� Machine conditions that process control

compensates for:� Dirty optics� Exposure lamp deterioration� Dirty charge corona wire/grid� Change of drum sensitivity� Deterioration of developer


Process control is a system that automatically changes machine processes to compensate for changes in the environment or the machine condition. The objective of process control is to stabilize the quality of image output. The practical result is a decrease in the frequency of service calls, thus increasing customer satisfaction and decreasing service cost.

To maintain good copy quality, a lot of machines do process control data initial setting just after the main switch is turned on.



Latent Image & Image Density Control


CTM > Process Control > Basic concepts

This illustration represents a copier model that uses two process control methods. One compensates for variation in the drum potential (latent image control) and the other controls the toner concentration and toner supply amount (image density control).All process control components affect one or the other (or both) of these methods.



Latent Image Control

Drum potential just after the exposure of the erase lamp.

VR (Residual Voltage )

Drum potential just after exposing the white pattern (VL pattern)

VL (Light Potential )

Drum potential just after exposing the black pattern (VD pattern)

VD (Dark Potential )

Drum potential just after charging the drum.

VO



The figure in the slide shows the changes of the drum potential during the copy process.The following list explains the meaning of some of the terms and abbreviations used when describing process control.VO (Original Potential)

� The drum potential after the drum is charged.VD (Dark Potential)

� The drum potential in black image areas after exposure. Standard VD is the potential measured after exposing a black pattern.

VL (Light Potential)� The drum potential in white image areas after exposure. Standard VL is the

potential measured after exposing a white pattern.VR (Residual Voltage)

� The drum potential after the drum has been exposed by the erase lamp.Potential Sensor

� A sensor used to measure the strength of the charge on the OPC drum surface (drum potential).

VL Pattern� A standard white pattern used for reference. On some machines the VL pattern

is actually a light gray tone rather than pure white.VD Pattern

� A standard black pattern used for reference.ID Sensor

� A photosensor that measures the image density (reflectivity) of the drum and of a test pattern (ID sensor pattern). The output of this sensor is used to control toner supply.

ID Sensor Pattern� A standard pattern that is exposed and developed for sensing by the ID sensor.




VSG� The ID sensor output when checking the erased drum surface.

VSP� The ID sensor output when checking the ID sensor pattern image.

VLAMP� Exposure lamp voltage.

VB or VBB� Development bias.

TD Sensor� Toner density sensor—it measures the concentration of toner in the developer.

VREF� A targeted control reference for the TD sensor. When VTD becomes too low,

toner is added to the developer to bring VTD back to the VREF value.VTD, VT, or VOUT

� The output voltage of the TD sensor.V Sensor

� A reflective photosensor similar to the ID sensor that is used to indirectly measure the drum potential. It was used prior to the development of the potential sensor system and will be found in earlier models using process control.

VG or VGRID� Charge corona grid potential.

VH (Halftone Potential)� A standard halftone drum potential. This value is used for laser power

adjustment in the process control system of some digital products.



Image Density Control� Toner density sens or (TD

sensor)

� Image density sens or (ID sensor)

ID Sensor TD Sensor



Data from the TD sensor is used to keep the toner concentration in the developer at a constant level. However, the image on the OPC drum varies due to the variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. By the ID sensor compensation, toner concentration is changed to keep the image density on the OPC drum constant.

The following items are controlled to maintain a constant copy image density:� Toner supply clutch on time� Toner supply level data (VREF) of the TD sensor

NOTE:Some machines do not have a TD sensor and use only an ID sensor for image density control.



OPC digital systems


CTM > Process Control > OPC Digital Systems

This training module will mainly focus on digital copiers, but all detail about OPC’s for analog systems is explained in the CTM.

� CTM > Process Control > OPC Analog Systems



OverviewThe drum potential will gradually change becauseof the following factors:� Dirty optics or exposure glass� Dirty charge corona casing and grid plate� Changes in drum sensitivity



In this OPC digital systems chapter we explain process control based on the model A229 (Aficio650 or SP5).For detail about the different process control descriptions you have to refer to the machines Service Manual and Product trainings.



Process Control Data Initial Setting� The following is done during process control

initial setting:1. Potential Sensor Calibration (Latent Image

Control)2. Vsg Adjustment (Image Density Control)3. Vg (Grid Voltage) Adjustment (Latent Image

Control)4. LD Power Adjustment (Latent Image Control)5. Vref Update (Image Density Control)

Potential SensorCalibration

VG Adjustment(VD Correction)

LD Power Adj.(VH Correction)

Latent ImageControl

Vsg Adjustme nt(ID Sens . Cal.)

Vref Update

Image Dens ityControl

Process Control



To maintain good copy quality, the machine does Process Control Initial Setting just after the main switch has been turned on.

NOTE:In most cases it is done if the fusing temperature is less than 100 °C and auto process control is enabled on the machine.

Next slides will describe these steps in more detail.

Processes 1, 3, and 4 in the above list compensate for changes in drum potential. Processes 2 and 5 are for toner density control.



Drum Potential Sensor Calibration(Latent Image Control)

-200/-700

RA102

RA101

To correct for environmental conditions



The drum potential sensor detects the electric potential of the drum surface.Since the output of the sensor is affected by environmental conditions, such as temperature and humidity, the sensor needs recalibration at times. This is done during process control initial setting. The development power pack has two relay contacts. Usually RA102 grounds the drum. However, to calibrate the sensor, RA102 and RA101 switch over and apply the power pack output voltage to the drum shaft.The machine automatically calibrates the drum potential sensor by measuring the output of the sensor when –200V and –700V are applied to the drum. From these two readings, the machine can determine the actual drum potential from the potential sensor output that is measured during operation.

During calibration, if the rate of change in drum potential sensor response to applied voltage is out of the target range, a SC (Service Call) is logged and auto process control turns off. The VG and LD power adjustments are skipped; VG is set to a value stored in a SP (Service Program) mode, and LD power is also set to a value stored in a SP mode.

Exercise:Check with help of the Service Manual the following problemDrum Potential Sensor ErrorSee the result in the manual and compare with the result underneath

� Definition D� The SC history is updated. The machine can be operated as usual.� The SC will not be displayed. All that happens is that the SC history is

updated.



Vsg Adjustment(Image Density Control )

� During the process control initial setting or by SP, the ID sensor output is calibrated by changing the LED light intensity



Vsg adjustment calibrates the ID sensor output for a bare drum to a standard value. It does this by changing the intensity of the light shining on the drum from the sensor. This is done automatically during process control initial setting, and it can also be done manually with an SP mode selection.If the ID sensor output cannot be adjusted to within the standard, a SC is logged and toner density control is done using the TD sensor only.Later in this module we will explain more detail about the ID sensor when Image Density control is explained.



-900V

DrumPotential

Original Density DarkLightVR

VD

VH-300V

Gradations

New Drum


The relationship between the drum potential and the original density is illustrated in the characteristic. In this example the drum potential of a new drum is 600 Volts. This means that with this drum potential we have the maximum density from white to solid black.



Vg Adjustment (VD Correction)(Latent Image Control)

Charge/GridP.P

SBICU

VD Must be constant(Target= -900V + 10V)

VG

The Potential on unexposed areas of the drum (VD) graduallychanges during drum life



The potential on unexposed areas of the drum (VD) gradually changes during drum life. To keep VD constant, the grid voltage (VG) is adjusted during process control initial setting. The SBICU checks VD using the drum potential sensor. If it is not within the target range (-900V +– 10V), the SBICU adjusts VG (Grid Voltage) through the Charge/Grid power pack to get the correct target voltage. For details of how the machine determines an abnormal sensor detection see the service manual of the copier.



-900V

DrumPotential

Original Density DarkLight

After many copies

New drum

VR

VD

VH’

VH

VD’

-300V

VR’

Older Drum


The relationship between the drum potential and the original density is illustrated in the characteristic. To get consistent copy quality throughout the drum’s life, this relationship must be maintained. Since this relationship changes due to various factors to the one represented by the red dotted line, compensation is required. Factors causing these changes occur in the optics and charge sections and in drum sensitivity. The residual voltage (VR) cannot be compensated even if exposure lamp voltage is increased. Therefore, the VR change has to be compensated by other means.



-900V

DrumPotential


VD

VH’

VH

VD’

-300V

VR’

VG Adjust

VG Adjustment


The drum potential tends to lower during drum life due to a decrease in the drum’s capacity to carry a charge. The main control board measures VD through the drum potential sensor and adjusts it to a target value by adjusting the grid bias voltage (VGRID). This is illustrated with the blue dotted line.Now that VD is back to normal you can see that VH is not correct, so the drum potential range is less than the 600 Volts which we had with a new drum.The next adjustment is to bring VH back.



LD Power Adjustment (VH Correction)(Latent Image Control)

LDDR

SBICU

VH Must be constant(Target= -300V + 20V)



This adjustment uses the drum potential sensor to keep the ID sensor pattern at the same density, so that VREF will be updated correctly (see some slides later). The VH pattern is developed using the current LD power (the density is the same as the ID sensor pattern).



-900V

DrumPotential


VD

VH

VD’

-300V

VR’

LD Adjust

LD Power Adjustment


The drum potential sensor detects the potential on the VH pattern. The LD power is adjusted until VH becomes –300V +–20V. This is done only during process control initial setting.For details of how the machine determines an abnormal sensor detection please refer to the Service Manual.

Now that the latent image is controlled the next thing which has to be done is the Image Density Control with help of the TD & ID sensors.



Toner Density Sensor

01

2

3

4

5

6

7

1 2 3 4 5

Sensor output [V]

Toner weight [wt %]

Vref


Developer consists of carrier particles (iron) and toner particles (resin and carbon). Inside the development unit, developer passes through a magnetic field created by coils inside the toner density sensor. When the toner concentration changes, the voltage output by the sensor changes accordingly.When new developer with the standard toner concentration is installed, developer initial setting must be performed by using an SP mode.



Toner Supply Criteria

01

2

3

4

5

6

7

1 2 3 4 5

Sensor output [V]

Toner weight [wt %]

Vref

VTD < Vref (Toner WT% is large )Decrease toner supply

VTD > Vref (Toner WT% is small)Increase toner supply


At every copy cycle, toner density in the developer is detected. The sensor output voltage (VTD) during the detection cycle is compared with the toner supply level voltage (VREF).



Toner Density Control

TD SensorOutput (VTD)

ID Sensor Output(VSP/VSG)

GAINPixel Count

Toner Supply Clutch On TimeCalculation

VREF Update

TD Sensor InitialSetting (VREF)

VT ReferenceVoltage (VREF)

VT ReferenceVoltage Update

(New VREF)


To stabilize toner concentration, toner supply amount (toner supply clutch on time) is controlled by referring to VREF and VTD. The toner supply amount is calculated at every copy.



Vref Update(Image Density Control )

� To sta bilize the concentration of toner in the dev elopment unit Vre f is updated usingVsp/Vsg and VTD

TD SensorOutput (VTD)

ID Sensor Output(VSP/VSG)

GAINPixel Count

Toner Supply Clutch On TimeCalculation

VREF Update

TD Sensor InitialSetting (VREF)

VT ReferenceVoltage (VREF)

VT ReferenceVoltage Update

(New VREF)


CTM > Process Control > OPC Digital SystemsEarlier in this module we already explained that during process control initial setting the ID sensor is calibrated with help of the Vsg adjustment.The image on the OPC drum changes due to variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. The image density sensor (ID sensor) directly checks the image on the OPC drum and shifts VREF data to keep the image on the OPC drum constant.VSG and VSP are checked by the ID sensor. There is no ID sensor pattern in the optics, however, a pattern image is made on the OPC drum by the charge corona unit and the erase lamp.

� VSG is the ID sensor output when checking the erased drum surface.� VSP is the ID sensor output when checking the ID sensor pattern image.

To compensate for any variation in light intensity from the sensor LED, the reflectivity of both the erased drum surface and the pattern on the drum are checked.



5.5 Standard Components� Light Sources� Sensors and Switches� Clutches, Motors, And Solenoids� Consumables

5.5 Advanced Copier T echnology > Standard Compon ents

Study the CTM > Standard Components and make sure that you understand:� Light Sources� Semiconductor Components� Sensors and Switches� Clutches, Motors, And Solenoids� Other Electrical components� Consumables



6. Service

6. Servi ce



Service Manual� CD ROM

� Hard Copy

6. Servi ce

What is the best way to use the service manual CD ROM’s.How to View FilesAll the technical documents on this disk are in the portable document format (PDF). To view them you must install either Adobe Acrobat Reader or Adobe Acrobat Exchange on your computer. You will find a version of Acrobat Reader for Windows in the RDR_SRCH directory of this disk. Please install it if you haven't already. There are two ways to quickly find the documents that you want on this disk. You can use the main contents file (CONTENTS.PDF) or use the full-text search function. (You will find more detail about this in the readme file on the CD ROM.)

Using the Contents FileJust open CONTENTS.PDF (in the "Contents" folder). It is arranged according to product or product family and has links to all the technical documents on this disk.



Tools

� Special Tools (Serv ice Manual)� Part Number� De scription� Q’ty

6. Servi ce

The chapter Special tools and Lubricants is always a topic described in the Service Manual. It will give an overview of the part numbers of the tools.A description gives you more detail about the tools.

Next slide will explain more detail about the test chart which you see in the tools table.



Test chart� The following new test

chart is released for B/W copiers.

6. Servi ce

Check the next page to have a better look at the test chart.Part Number Description A2929500 Test Chart – S5S (10 pcs/set)

A: Leading edge registration (Max. A3/DLT size copier)B: Side-to- Side registration / Skew (Max. A3/DLT size copier)C: Leading edge registration (Max. A4/LT size copier)D: Side-to- Side registration / Skew (Max. A4/LT size copier)E: Jitter (Max. A3/DLT size copier)F: White line(s) in half tone area (Max. A3/DLT size copier)G: White line(s) (Max. A3/DLT size copier)H: Main scan / horizontal magnification (Max. A3/DLT size copier)I: Sub scan / vertical magnification (Max. A3/DLT size copier)J: Solid black areaK: Photo imageL: Scanning bit error (Max. A3/DLT size copier)N: LetterM: Uneven image density (Max. A3/DLT size copier)O: Jitter (Max. A4/LT size copier)P: Uneven image density (Max. A4/LT size copier)Q: White line(s)R: Sub scan / vertical magnification (Max. A4/LT size copier)S: Scanning bit error (Max. A4/LT size copier)T: Main scan / horizontal magnification (Max. A4/LT size copier)U: White line(s) in half tone area (Max. A4/LT size copier)V: ID balance of solid black areasW: Resolution



Troubleshooting� Service Manual� Operating Instructions

6. Servi ce

The Service Manual will explain all the necessary detail about troubleshooting procedures for the device.Also Operating Instruction sometimes have a chapter related to troubleshooting. In case the problems are more complicated and solutions are not given by any of these manuals, contact a Product Specialist in your organisation.



Maintenance� Service Manual� Operating Instructions

6. Servi ce

The Service Manual and Parts Catalogue will explain all the necessary detail about Preventive Maintenance for the device.It is even possible that devices are customer maintainable, in this situation there is also an Operating Instruction (maintenance guide) available.



Firmware

6. Servi ce

There are different ways to upgrade the firmware, this depends on the product.Some examples of firmware upgrade procedures are:

� EEPROM� Via the network� Flash memory card� Other

EEPROMElectrically Erasable Programmable Read-Only Memory. An EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM. EEPROM is similar to flash memory (sometimes called flash EEPROM). The principal difference is that EEPROM requires data to be written or erased one byte at a time whereas flash memory allows data to be written or erased in blocks. This makes flash memory faster. PROMProgrammable Read-Only Memory. A PROM is a memory chip on which data can be written only once. Once a program has been written onto a PROM, it remains there forever.RAMRandom Access Memory, a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers, they lose their contents when the power is turned off.There are two basic types of RAM:

� dynamic RAM (DRAM) � static RAM (SRAM)

ROMRead-Only Memory, computer memory on which data has been prerecorded. Once data has been written onto a ROM chip, it cannot be removed and can only be read. Unlike RAM, ROM retains its contents even when the computer is turned off. ROM is referred to as being nonvolatile, whereas RAM is volatile.



Getting a source file� Notes database

� Software Di stribution Database

� Interne t� www.ricoh-suppo rt.com

6. Servi ce

To get more information about how to deal with procedures and logins, your Service Manager has all the details.



Desktop Computer� Application software is required (SWAPFTL)

++6. Servi ce

� SwapFTL software allows a flash memory card to be used as an intermediate medium between a flash ROM (or RAM) on the machine and a Windows 95 based computer.

The basic procedure is as follows:1. You receive ROM firmware files from a database either via network or via

physical medium, and save them onto your computer’s local hard disk. A computer can work as a flash memory card programmer after a SwapBox andSwapFTL software is installed.

2. You program the ROM file to a flash memory card using this software.3. You carry the programmed card to a machine site and download the ROM data

from the card to the machine’s internal flash ROM. The 4MB flash memory card that is customized for this application is available as a special tool. You cannot use other types of flash memory cards.

4. After downloading ROM data to one machine, you can use the same card with another machine of the same type.



Laptop� Application software is required (SWAPFTL)

++

6. Servi ce

SWAPFTL is an application designed for the Swapbox hardware, that means that the software on a laptop with his own card interface (called PCMCIA slot) can have problems. Refer to the SwapBox & SwapFTL Service Manual for more detail about this.



Download to a machine

� Plug the card into the card slot

6. Servi ce

The procedure to download firmware to the machine is depending on the type of product.This procedure is always described in the machines Service Manual.



7. Information Flow � Service Manuals� Parts Catalogues� Modification Bulletin� Ricoh Technical Bulletin� Ricoh Technical Tip

7. Information Flow

It is very important that the information flow is known in the organisation.Some information which should be available:

� Service Manuals� Parts Catalogues� Technical Bulletins and Notes (CD or hardcopy)� Other relevant service related information

For Ricoh distributors there is a document called Customer Service Policy.In this policy, you will find guidelines and procedures you may require when servicing a product. Your service manager knows all about this document.



Service Manuals� The Serv ice Manual

consists of:� machine description� detailed installation� and service inst ructions

and service tables for maintenance.

7. Information Flow

The Service Manual consists of:� machine description� detailed installation� and service instructions and service tables for maintenance.



Parts Catalogues� Landscape la yout

� The Parts Catalogue contains:� all parts� part numbers� part descriptions� exploded views of the

machines.

7. Information Flow

As you can see in the slide the layout of the PC is landscape. That means that the top page shows the part layout and the bottom page shows the details.The Parts Catalogue contains:

� all parts� part numbers� part descriptions� exploded views of the machines.

The Service Manuals and Parts Catalogues are issued on a CD ROM. There is a standard annual fee for the CD ROM and a new update will be sent every 3 (three) months. If your organisation does not make use of them, then you have to make use of the hardcopy.Earlier we discussed that for maintenance the Service Manual and Parts Catalogue are used to explain all the necessary detail about Preventive Maintenance for the device. In the PC there is a topic called PM Parts Index, this will give you a nice overview of all the PM parts for the Machine.Example:



Modification Bulletin (MB)� Issued when any

modi fication is applied to a product.

7. Information Flow

A Modification Bulletin (MB) will be issued when any modification is applied to a product. Part number change, interchange ability, reason for modification and the serial number of the machine will be provided. This information can be found on the Technical Documentation database in Lotus Notes which is normally only used by a product specialist, but the MB’s will also be provided on the Service Manuals CD ROM’s for each product.

Example:



Ricoh Technical Bulletin (RTB)� A Ricoh Technical Bulletin

is issued when technical information is require d in the field.

7. Information Flow

A Ricoh Technical Bulletin is issued when technical information such as troubleshooting, modification kits and the latest manual information is required in the field. This information can be found on the Technical Documentation database in Lotus Notes which is normally only used by a product specialist, but the RTB’s will also be provided on the Service Manuals CD ROM’s for each product.

Example:



Click here for Bulletins

� Click here for bulletins:� MB’s� RTB’s

7. Information Flow

How to find bulletins.On the Service Manuals CD ROM’s you can select a product, after you selected a product there is a possibility to click on bulletins (red text).Now you have all the MB’s and RTB’s for the selected product in view.



Ricoh Technical Tip (RTT)� A Ricoh Technical Tip will

be issued when addi tional information in the field is necessary.

7. Information Flow

A Ricoh Technical Tip will be issued when additional information in the field is necessary. This information can be found on the Technical Documentation database in Lotus Notes which is normally only used by a product specialist, RTT’s are NOTprovided on the Service Manuals CD ROM’s.Ask your instructor or product specialist if this information is distributed in your organisation.Example:



8. Specifications� Service Manual� Operating Instructions

8. Specifications

The Service Manual will explain all the necessary detail about Specifications for the device. Normally this is divided in several topics like for instance:

� General Specifications� Machine Configuration� Optional Equipment

Also Operating Instructions have a chapter related to Specifications.



End

��Basic Copier module

for service master Exercise Functions and features

Functions and FeaturesFunctions and FeaturesFunctions and FeaturesFunctions and Features 1 Objective

��Operate a copy machine

��Understand basic and advanced functions

��Operating Instructions

2 Required materials

��1 copier with ADF and Finisher

��Operating Instructions

��Test charts

3 Overview

1 OBJECTIVE........................................................................................................................................................................................................1 2 REQUIRED MATERIALS............................................................................................................................................................................1 3 OVERVIEW.........................................................................................................................................................................................................1 4 INTRODUCTION .............................................................................................................................................................................................2 5 IMAGING.............................................................................................................................................................................................................2

5.1 IMAGE DENSITY............................................................................................................................................................................................2 5.2 ENLARGE / REDUCE....................................................................................................................................................................................2 5.3 PHOTO MODE / TEXT MODE.......................................................................................................................................................................2 5.4 POSITIVE / NEGATIVE .................................................................................................................................................................................2 5.5 IMAGE REPEAT / POSTER MODE................................................................................................................................................................3

6 PAPER SELECTION.......................................................................................................................................................................................3 6.1 INPUT SELECTION ........................................................................................................................................................................................3 6.2 OUTPUT SELECTION ....................................................................................................................................................................................3

7 OUTPUT SELECTIONS................................................................................................................................................................................3 7.1 SAMPLE COPY ...............................................................................................................................................................................................3 7.2 SIMPLEX / DUPLEX......................................................................................................................................................................................4 7.3 BOOKLET / MAGAZINE...............................................................................................................................................................................4

8 FINISHING OPTIONS....................................................................................................................................................................................4 8.1 PUNCH ............................................................................................................................................................................................................4 8.2 STAPLE ...........................................................................................................................................................................................................4 8.3 SORT................................................................................................................................................................................................................4 8.4 STACK.............................................................................................................................................................................................................5

Ricoh Europe B.V. Technical Training Centre www.get-u-wice.com

Last Modified 06-07-2001

PAGE 1

4 Introduction

These exercises will help to have a better understanding on how to operate a copier. These exercises can be done on a standard digital copier but the ADF and Finisher should be installed to get a better overview of all functions. It is possible that not all functions are available on your copier, in that case move to the next exercise.

5 Imaging

5.1 Image density

Put an original in the ADF. Change the image density to the lightest position. Make a copy. Put the same original in the ADF. Change the image density to the darkest position. Make a copy. Compare the two copies and see the difference. To go back to default settings press the cancel button, now your machine settings are back to default.

5.2 Enlarge / Reduce

Put an A4 original on the platen glass. Select 141% enlargement. Select A3 from the paper tray and make a copy. Q1: Does the copy fit on the A3? ………………… Put the just copied A3 on the platen glass. Select 70% reduction. Select A4 from the paper tray and make a copy. Q2: Does the copy fit to A4? ……………. Q3: What is the biggest enlargement setting on your machine? …………………

5.3 Photo mode / Text mode

Put an Original with a photo on the platen glass. Select photo and make a copy. Select text and make a copy. Q4: Which setting is better for copying photo’s, photo or text mode? …………………………… Q5: What will happen if you select photo mode with a text original? ………………………….

5.4 Positive / Negative

Put an original on the platen glass. Select Photo mode. Select positive/negative and make a copy. Change the density to the darkest position and make a copy again. Q6: Why is the density setting reversed? ………………….

5.5 Image repeat / Poster mode

Put an original on the platen glass. Select 4 pages on 1 sheet and make a copy. With poster mode the machine will enlarge your image. If you put all the copies together you get a poster.

6 Paper Selection

6.1 Input Selection

Default the machine is set on Auto paper select. When an original is placed on the platen glass or ADF the machine will scan its size. If the original size is known, the right paper from the tray will be selected automatically. Put an A4 original LEF on the platen glass or ADF. Select A3 and make a copy. Put an A4 original LEF on the platen glass or ADF. Select a paper tray with A4 SEF and make a copy. Q7: Is the complete image copied or do you miss a part of the image? …………………. Put an A4 original SEF on the platen glass or ADF. Select A4 LEF and make a copy. Q8: Is the complete image copied or do you miss a part of the image? …………………. Put an A4 original SEF on the platen glass or feeder. Select auto paper select and make a copy. Q9: Which paper tray did the machine use? ………………. Q10: Is the complete image copied or do you miss a part of the image? …………………. Put an A4 sheet into the bypass tray. Put an original on the platen glass or ADF. Select bypass tray and make a copy. Q11: Can the machine detect the paper size from the bypass automatically? ……………………

6.2 Output Selection

When a finisher is installed you can select more output bins. Put an original on the platen glass or ADF. Select the internal tray for the output and make a copy. Do the same but select a finisher output bin. Q12: Where did you find these setting? …………………………………….

7 Output Selections

7.1 Sample copy

On the keypad you select the number of copies. Put an original on the platen glass or ADF. Select 3 copies on the keypad. Press the sample copy button. Q13: How many copies are being made? …………………. The machine will ask print or suspend select print, select print. Q14: How many copies did come out in total? …………….

7.2 Simplex / Duplex

The machine wants to know if the original is simplex or duplex. You can only scan duplex originals when an ARDF is installed. For the output we can select simplex or duplex. Put 4 originals in the ADF. Select for the output duplex and press the start button. Check if the copies are duplex.

7.3 Booklet / Magazine

The words booklet and magazine do have the same meaning. The only difference is how to combine the sheets to make a book. With booklet/magazine it is possible to create a complete book. After printing we need to do something extra, fold and staple (saddle stitching). Our machine is not capable to do this operation. Put 4 numbered (1,2,3,4) A4 originals in the ADF. Select booklet/magazine and press the start button. Fold the A3 copy and check that the numbers are in the right order. Try to make your own magazine. Place your originals 2 by 2 next to each other on the platen glass. Select duplex and select the A3 paper tray and press the start button to scan the first two pages. Now put the other 2 originals on the platen glass and press the start button. Q15: In which order do you have to put your originals to get the correct page numbering? ……….

8 Finishing Options

8.1 Punch

The punch hole will be made during the paper transportation in the finisher. The holes will always be on the correct side of the paper unless if you select simplex or duplex. Put 2 originals in the ADF select duplex and punch. Press the start button and check if the punch holes are made.

8.2 Staple

Stapling is done in the finisher. Put two originals in the ADF, select staple and press the start button. Q16: Will you get a staple if you put only 1 original in the ADF? ………………. Q17: Is it possible to select staple and punch for the same copy job? …………………. Q18: If you select staple the sort function will be selected also, why? ………………………

8.3 Sort

Put 3 A4 originals into the ADF. Check that the paper selection is set to auto. Select 1 set to copy and press the start button. Q19: Has the output the same order as the originals? …………………… Put the same 3 A4 originals into the ADF. Select 3 sets to copy and press the start button. Q20: Is the output order still the same as the originals? ……………… Q21: Which function must be selected to get the same order as the originals? ………………

8.4 Stack

On almost all machines stack is selected automatically if you select sort. Put 3 originals in the ADF, select stack and press the start button. Check the output.

End of this exercise.

T e c h n i c a l T r a i n i n g M a n u a l

2

C o p i e r

C o p y P a p e r

G l o s s a r y

3

Analogue copier

Digital copier

• Copy process overview

• A closer look

• Scanning

• Shading

• Laser Exposure

• Development

C o p i e r

4

Analogue copier

C o p i e r


• A closer look

5

Analogue copier

C o p i e r


• A closer look

Step 2 PhotoconductorIn the dark, the photoconductor receives an electrostaticcharge. This electrostatic charge remains on the photocon-ductor until it is exposed to light. The charge disappearson places where light reflected from the original reachesthe photoconductor. Darker parts of the original reflect lesslight and there the electrostatic charge will remain on thephotoconductor as the latent image.

Step 3 Toner on latent imageAfter exposure, the remaining charge on the photoconduc-tor will attract toner when the charged areas pass thedevelopment unit.

Step 4 Transfer to paperThe paper is fed through the machine and is synchronisedwith the image on the photoconductor.The toner on the photoconductor is transferred to the paperby an electrostatic charge applied to the back of the paper.

Step 5 FusingPaper is fed between two rollers and a combination of heat and pressure permanently melts the toner into thecopy paper.

Step 2

Step 3

Step 4

Step 5

Step 1

Step 1 ScanningAn original document isplaced on the platen glass.A bright light illuminates theoriginal, and its image isreflected through the optical system towards thephotoconductor’s surface.

6

Analogue copier

C o p i e r


• A closer look

Scanning •

Photoconductor •

Process around the photoconductor •

Paper feed and registration •

Fusing •

A. ScanningThe original document is placed on the platen glass either by hand or automatically via a document feeder.

B. AbsorbingThe exposure lamp illuminates the original. Light areas on the original reflect light, and dark areas absorb light.

C. Exposure to photoconductorThe light reflected from the exposed original now must travelthrough the optical system. Light areas remove the chargefrom the photoconductor surface. Dark areas leave thecharge in place. The difference in charge creates an electro-static copy of the original image, also known as the latentimage, on the photoconductor.

B

A

C

7

C o p i e r

D. LensThe lens gathers and focuses the reflected light onto thephotoconductor surface. It is situated in the middle of theoptical path for making copies that are the same size as the original.

E. EnlargementThe image is enlarged if the lens is positioned closer to the original. This action enlarges the image over the width of the photoconductor. In order to enlarge the image aroundthe entire photoconductor, the copier reduces scanner speedwhile maintaining the same photoconductor speed. The thirdscanner is moved to keep the image in focus on the photo-conductor.

F. ReductionThe image is reduced if the lens is positioned further awayfrom the original. This action reduces the image over thewidth of the photoconductor. In order to reduce the imagearound the entire photoconductor, the copier increases scanner speed while maintaining the same photoconductorspeed. The third scanner is moved to keep the image infocus on the photoconductor.

E

D

F

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

8

C o p i e r

A photoconductor is made of light-sensitive material. In the dark it acts as an isolator, keeping the charge by notallowing any electric flow. When exposed to light, the photo-conductor acts as a conductor and loses the electric charge.

Non-image areas on the original reflect light onto the photo-conductor, discharging that area. Such areas will not attracttoner. Image areas on the original do not reflect light ontothe photoconductor and, thus, attract toner.

Photoconductors come in the form of belts and drums. There are two types:

- Selenium photoconductors are positively charged andattract negatively charged toner.

- OPC (Organic Photo Conductor) photoconductors are negatively charged and attract positively charged toner.OPCs are safer to handle than other varieties, some ofwhich are made from toxic materials.

The type of photoconductor most widely used with Ricoh copiers is a cylindrical OPC drum.Drum

Belt

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

9

C o p i e r

A combination of layers forms the photoconductor. The main layers of the photoconductor are the:

1. Substrate2. Under layer3. Charge generation layer4. Charge transfer layer

The Substrate is the base for the other layers and is made of aluminium. It is a good conductor and provides the electrical grounding for the photoconductor.

The Under layer is a super-thin layer that maintains acharge by preventing electrons from moving too easily to the Substrate, giving the base a better grip on the next layer.

The Charge generation layer isolates the charge build-up inthe Charge transfer layer in the dark, but when exposed tolight it conducts the charge to the grounded Substrate.

The Charge transfer layer is very similar to the Under layerbecause it, too, prevents electrons from moving too easily to the Charge generation layer. In addition, it acts as a trapfor the electrostatic charge.

Substrate

Under layer

Charge generation layer

Charge transfer layer

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

10

C o p i e r

Process around the photoconductorWhen copying, several processes take place. The processaround the photoconductor is a crucial element of the copy-ing procedure. The following are the key components of thisprocess explained in more detail.

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

11

C o p i e r

A. Charge

A1The charge circuit applies a uniform charge to the photocon-ductor surface. Most copiers use a high negative DC voltagebrought into contact with the air by a very thin, un-insulatedwire called a corona wire.

A2When high negative voltages are applied to the corona wire,the air around the wire becomes negatively charged. A nega-tive voltage on the corona wire means there is an excess ofelectrons on it. The corona wire releases some electrons tothe air molecules around the corona wire. These negativelycharged air molecules are known as negative ions.When a negative ion approaches the Charge transfer layer,an electron is released to this layer. At this time, the Chargetransfer layer receives a negative charge. Since the OPCphotoconductor does not conduct in the dark, this layerremains charged until exposed to light. A charge fan makessure the ions evenly charge the photoconductor.

A3 A grid is used to control the amount of charge that reachesthe photoconductor. Whereas a very high voltage on thecorona wire is needed to create ions, the charge needed on the photoconductor is much lower. A grid bias voltageensures that a certain amount of charge reaches the photoconductor, and the excessive charge is conducted to ground.

A4 Some photoconductors are charged with the help of a conductive charge roller. The charge roller directly chargesthe photoconductor.

A2

A2

A3

A4

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

A1

A

12

C o p i e r

B. Exposure

During exposure, the charged photoconductor is exposed tolight reflected from the original.

Light areas remove the charge from the surface. Dark areasleave the charge in place. The differences in charge createan electrostatic copy of the original image on the photocon-ductor, also known as the latent image. Besides white and dark areas there are also many shades ofgrey. These areas partly discharge the photoconductor. Thismeans these areas attract toner in proportion to the densityof the original.

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

B

13

C o p i e r

C. Development

In the development stage, toner is transferred to the latentimage on the photoconductor. The latent image is developedwhen negatively charged areas attract positively charged toner.There are two basic types of development:

1. Mono-component development 2. Dual-component development

Mono-component developmentMono-component developer consists only of toner. The toneritself consists of resin and ferrite. Ferrite gives the tonermagnetic characteristics. The toner comes into contact withthe latent image on the photoconductor surface, and thecharged areas attract toner.

Dual-component developerMost copiers use a dual-component development system.The first component is carrier, an iron-based material that isattracted to magnets in the development roller. Carrier staysin the development unit during the copy process. The secondcomponent is toner. Toner is the fine powder that gives theimage its color.Inside the development unit toner and carrier are mixedtogether to form developer.The mixing action gives the toner a positive electrical charge,which allows the toner to be attracted to the negative latentimage.

During development the photoconductor comes in contactwith the developer on the development roller. The carrierstays in the development unit and the toner is attracted tothe latent image. The ratio of toner to carrier must be kept ata proper level to maintain constant copy quality.

Toner and Carrier

Mono-component

Dual-component

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

C

14

C o p i e r

D. Transfer

The transfer function moves the toner from the developedimage on the photoconductor surface to the passing copy paper.

As paper is fed past the photoconductor a high charge is applied to the back of the copy paper. This charge isstronger then the latent image on the photoconductor and attracts toner onto the paper.There are two ways to charge the paper:

1. By using a transfer corona2. By using a transfer belt

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

D

15

C o p i e r

E. Separation

After transferring the image from the photoconductor to thepassing paper, the paper must be separated from the photo-conductor surface and transported to the fusing unit.

A separation corona applies an AC current to the paper toneutralise the paper charge. If a transfer belt is used a sepa-ration corona is not necessary.

With the force of attraction neutralised, the paper’s own stiffness usually separates it from the photoconductor.

Pick-off pawls mechanically separate the paper from thephotoconductor if electrical separation was unsuccessful.

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

E

Separation Corona

Pick-off pawl

16

C o p i e r

F. Cleaning

After transfer and separation we finally have something thatlooks like a copy. Nearly all the toner has transferred to thepaper, but a very small amount remains on the photoconduc-tor and must be removed by the cleaning system.

A rubber-cleaning blade contacts the photoconductor surface.The remaining toner is gently scraped off the photoconductorsurface by the cleaning blade. Sometimes a cleaning brushis used in combination with a cleaning blade.

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHING

F

17

C o p i e r

G. Quenching

After cleaning, the toner is gone but the latent image is stillthere. At this point the charge is slightly weaker than it wasimmediately after exposure, but it is still strong enough topick up toner during development. Light from the quenchinglamp discharges any electrical potential on the photoconduc-tor’s surface.

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

CHARGE

EXPOSURE

DEVELOPMENT

TRANSFER

SEPARATION

CLEANING

QUENCHINGG

18

C o p i e r

Paper feed and registration

There are different systems used to feed paper through acopier. All paper-feed systems are based on the differentfriction between feeding system and paper.When the feed roller starts feeding the top sheet into thecopier, sometimes the sheet underneath sticks to it. The topsheet has to be separated from the bottom sheets.The two most common feed systems are:1. A feed roller and a friction pad2. The Feed and Reverse Roller system (FRR)

A (friction)A cork friction pad is used to hold the bottom sheet backwhile just the top sheet is fed. The friction between the corkpad and the bottom sheet is larger then the friction betweenthe sheets of paper.

B (FRR)The feed and reverse roller system uses three rollers. Thepick-up roller feeds the sheet of paper. The reverse roller isdriven in reverse through a slip clutch. The reverse roller willfeed the bottom sheet back because the friction of the slipclutch is larger than the friction between the sheets of paper.If there is only one sheet between the feed and the reverseroller, the clutch will slip and the reverse roller will rotate inthe feed direction.

A

B

Pick-up roller

Reverse roller

Transfer roller

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

19

C o p i e r

C (Registration)The registration rollers have two functions. The first is to correct for skew. Skew means that the paper’s leading edgeis not parallel to the drum. The feed rollers push the paperagainst the registration rollers and create a buckle, causingthe leading edge of the paper to align with the registrationrollers. The second function of the registration rollers is toalign the paper with the image on the photoconductor. The registration rollers start to feed the paper when the reg-istration clutch is energised. The copier’s electronic circuitscontrol the clutch.

C

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

20

C o p i e r

Fusing

Paper is fed into the fusing section between a hot roller anda pressure roller to fuse the toner into the paper. At powerup the CPU turns on the fusing lamp, warming the hot roller.The lamp is turned on and off to maintain the proper temper-ature based on the signal of a thermistor.A thermofuse gives back-up protection against overheating.When the front cover is opened, safety interlock switchesshut off the power to the fusing unit.

Analogue copier


• A closer look

Scanning •

Photoconductor •



Fusing •

21

C o p i e r

A digital scanner and a laser printer are the twofundamental elements of a digital copier. Thedigital copying process consists of four steps.First, a document is scanned to a ChargeCoupled Device (CCD). Next, the analogueinformation from the CCD is converted into digi-tal information. The digital information is thensent by the Image Processing Unit (IPU) to thelaser for writing on the photoconductor.

There are several important differencesbetween analogue and digital copying. To beginwith, digital copiers are capable of more featuresthan analogue copiers. Once the document isturned into digital information, various imagequality-related and sorting features are possible.Another difference is in the developmentprocess. Analogue copiers use positive tonerthat is attracted to a negatively charged latentimage, whereas digital copiers contain nega-tive toner that is attracted to a less-negativelatent image.

Digital copier

22

C o p i e r

Digital copier

• Scanning

• Shading

• Laser Exposure

• Development

23

Digital copier

C o p i e r

• Scanning

• Shading

• Laser Exposure

• Development

Step 1During scanning the original document is illuminated by an exposure lamp. To scan the original, either the docu-ment or the lamp must be moving. In most digital copiersthe document remains stationary on the exposure glassduring scanning.

Step 2Some machines use a stationary scanner and the docu-ment is moved past the exposure lamp during scanning.

Step 3Light from the original is reflected through mirrors and a lens to a Charge Coupled Device (CCD). The CCD is a row of small photocells also referred to as picture elements, or pixels. They convert the light reflected from the original into an electric charge.

Step 4The charges are stored as a separate voltage level foreach pixel. These voltages are output serially from theCCD as analogue image signals. These signals areamplified and converted from analogue to digital. Each electric charge from the CCD is converted into a digital value based on its voltage level.

1

2

3

4

24

Digital copier

C o p i e r

• Scanning

• Shading

• Laser Exposure

• Development

Step 5The digital signal is sent to the Image Processing Unit(IPU). The signal can be manipulated to perform featuresthat are not possible on analogue machines. Digital processing is also used to compensate electronically for limitations of various components.

Two examples are smoothing, which enhances reproduc-tion of greyscales, and the Modulation Transfer Function(MTF) which improves fine details.MTF

Features

Smoothing

25

Digital copier

C o p i e r

• Scanning

• Shading

• Laser Exposure

• Development

In digital copiers, Auto Shading must be performed beforean original document is scanned.Auto Shading compensates for variations in the output ofeach individual photocell. Such variations are caused by the different sensitivities of individual photocells, optical distortions and the fact that the fluorescent lamp is brighterat its centre than it is at its ends.

There are two Auto Shading processes:1. White Shading 2. Black Level Correction

White shading and Black Level Correction eliminate distor-tions by ensuring that the signals received from everyphotocell in the CCD contain only image data.

White shading is performed with the exposure lamp on.Light reflected from the white reference plate generates acharge in every photocell. The CCD outputs are adjusted to the same white level during white shading. This correctionis stored in RAM, and the output of the photocell is modifiedduring every main scan.

Black Level Correction is done with the lamp off. Since nolight is being reflected to the CCD, all photocells should generate zero volts. Black Level Correction stores in RAMthe voltage level of any photocell that generates a charge.That voltage level will be subtracted from the output of thephotocell during each main scan.

26

Digital copier

C o p i e r

• Scanning

• Shading

• Laser Exposure

• Development

Based on the digital image data, the laser diode turns onand off to illuminate areas of the photoconductor via a rotat-ing polygon mirror and lenses. Each surface of the polygonmirror reflects one horizontal line, or main scan, of the laseracross the photoconductor’s surface. The polygon mirror isdriven at a very high speed.

The charge is reduced on the illuminated areas of the pho-toconductor. The pattern of low and high voltages on thephotoconductor is referred to as the latent image.

In analogue copiers the non-image areas are exposed tolight. In digital copiers the image areas are exposed. This is called write-to-black. In digital copiers toner has a highnegative charge. The negative toner is transferred to thedischarged areas of the drum.

The laser also hits a synchronisation detector. This givesthe starting signal to write the data to the photo conductor.

The laser light is kept in focus by a lens between the polygonmirror and the photoconductor’s surface. The f-theta lensesassure proper spacing of the pixels on the photoconductor.Lighter or darker shades of grey are produced by changingboth the laser power and the time the laser stays on foreach pixel.

27

Digital copier

C o p i e r

• Scanning

• Shading

• Laser Exposure

• Development

The areas exposed by the laser attract toner. The tonerused in digital copiers is negatively charged and is attractedto the areas discharged by the laser because they are more positive.

28

Paper sizes

Paper weight

Paper grain

Paper curl

Front and back

sides of paper

C o p y p a p e r

Metric Paper

Letter Paper

letter 11 inch

8.5 inch

Double letter 11 inch

17 inch

29

Paper sizes

C o p y p a p e r

There are two main paper sizes: Metric paper and Letter paper.

• Metric paper has two sizes: A size and B size.

An example of A size paper is A3.An A3 sheet is 297 by 420 millimeters.An A3 sheet is the same size as two A4 sheets.

An example of B size paper is B4.The size of a B4 sheet is 257 by 364 millimeters.A B5 sheet is half the size of a B4 sheet.

• Letter paper is defined in inches. A letter sheet of paper is 8.5 by 11 inches and is wider than A4.Double Letter or Ledger is 11 by 17 inches.Legal size is 8.5 x 14 inches.

d297 mm

297 mm

148.5 mm

210 mm

420 mm 210 mm

A3A5

A5

A4

Asize

d 364 mm

182 mm

257 mm

257 mm

B5

B5

B4

Bsize

30

Paper weight

C o p y p a p e r

Paper weight is specified in grams per square meter (g/m2)or in pounds (lb). For example, 100 gram paper weighs 100grams per square meter; 20 lb paper means that 500 sheetsof paper weighs 20 pounds. Plain paper copiers normallyuse 20 lb paper in North America and the U.K., and 80 grampaper in most other places. Colour copiers commonly use 24 lbpaper in North America and the U.K., and 100 gram paper inmost other places.

1 meter1 meter

100 grams

500 sheets

31

Paper grain

C o p y p a p e r

The direction of fibers in the paper is known as the grain andis either along the long edge of the paper or along the shortedge of the paper. Paper is stiff along the direction of the grain.Grain along the long edge of the paper is called long grain.Grain along the short edge of the paper is called short grain.The paper grain should be in the same direction as the paperfeed because then it easily separates from the photoconductor.

To check the grain, fold a piece of paper. Once it is folded,open it and check the back of the paper. If the paper is foldedin the same direction as the paper grain, the folded line is aclear line. If not, it is a wrinkled line.

f

fFibers

32

Paper curl

C o p y p a p e r

Excessive paper curl can cause paper jams, separationproblems and mis-feeds. Paper curl also limits the amount of paper that can be stacked on the exit tray or sorter.

There are several causes for paper curl. Humidity causespaper curl because of moisture. The fusing stage also causes heat curl because of high temperatures.

To check paper curl direction, moisten a piece of paper. The fibers become thicker when exposed to humidity, meaningthe paper will stay straight in the direction of the grain andcurl on the sides.

33

Front and back sides of paper

C o p y p a p e r

There are some differences between the front and backsides of paper. A higher density of fibers makes the surfaceof the front side smoother. The higher density also causesthe front side to expand more compared to the back.

The arrow on the paper package shows the side of paperthat should receive the image.

Paper

Paper

34

G l o s s a r y

AGITATORa type of mechanical mixing device; used in copiers in the toner supply to keep toner particles separated;also used in the development unit to combine toner and carrier, creating two-component developer.

ALTERNATING CURRENT (AC)a type of electrical flow (current) which reverses its direction of travel according to some regular cycle.

ALUMINIUM OXIDEa chemical combination of aluminium and oxygen; used as an intermediate layer between the structural aluminium base and the light-sensitive selenium layer in selenium photoconductors, providing a better bond than is possible between selenium and metallic aluminium.

AMORPHOUS SILICONa photoconductive material used in some copiers; it offers a durable surface, is highly sensitive to light, and can produce copies with excellent resolution.

ANALOGUE METERan electronic instrument used to measure electrical voltage, current or resistance, which displays an individ-ual reading using a needle that moves along a calibrated scale; good for detecting transients or “spikes” incurrent flow. (See also DIGITAL METER)

AUGERa screw-type mechanical transport device used to move bulk materials in many different applications; relieson a large screw with deep, wide-pitched threads turning inside a close-fitting cylinder-the threads act like an endless scoop or wedge to lift material from one end of the cylinder to the other; used in some copiers totransport used toner from the cleaning unit to the development unit for reuse or to a used toner storage area.

BIASan electrical signal applied to a given component to achieve a specific controlling effect over that component's performance; AC and DC bias signals of widely differing voltages, currents and frequencies are commonly used in tape recorders, radios and copiers.

BIAS CIRCUITused in a copier's development system to control image density and prevent toner background on copies;creates a certain amount of electrical attraction at the surface of the development roller, thereby controllingthe amount of toner which transfers to the latent image.

BASE BOARDpart of the OPC which develops the counter charge to the charge developed on the Charge Transfer Layer (CTL);made of either aluminium drum, nickel or polyester film.

BIAS ROLLERused in a copier's cleaning system to apply an electrical charge to the cleaning brush; this charge helps thebrush loosen toner particles more effectively than it could with mechanical action alone. (See also CLEANING BRUSH)

BLOCK DIAGRAMa kind of electronic map that divides a system into a number of functional “blocks”; it shows all the intercon-nections among the blocks, but generally does not show detail inside them.

BONDa category of papers consisting of many individual types; most bond papers are suitable for use in plain-paper copiers.

BRIGHTNESSthe quality of light that refers to its ability to carry more or less energy- the brighter the light, the more energyis involved; also referred to as intensity.

35

G l o s s a r y

CARRIERone of the components of two-component developer; carrier consists of tiny iron-based beads; the beadsattract toner particles through a triboelectric charge and transport them to the photoconductor during thedevelopment process. (See also TRIBOELECTRIC CHARGE)

CENTRAL PROCESSING UNIT (CPU)a microprocessor chip or other Very Large Scale Integrated Circuit (VLSI), used as the primary control and information processing device in a sophisticated electronic system; CPU chips are commonly found in personal computers, fax machines and copiers.

CHARGEthe first step in the copy process; during the charge process, an even electrical charge is applied to the photoconductor, preparing it to receive the image of an original during exposure; usually accomplished with a corona unit.

CHARGE COUPLED DEVICE (CCD)a solid-state component made from a number of very small light-sensitive elements; the amount of light falling on each element produces an electrical signal of corresponding strength; CCDs are used in laser-based copiers, fax machines and some television cameras.

CHARGE GENERATION LAYER (CGL)part of the OPC which generates the charge from the absorption of light; generally made of azo pigments andplastic binders (Analogue and digital OPCs have different colour pigments; in analogue OPCs the pigment isa dark blue color; digital OPCs have a green pigment.)

CHARGE TRANSFER LAYER (CTL)one of the layers of the OPC; the charge generated in the Charge Generation Layer (CGL) is transmitted throughthis layer to the surface of the photoconductor; generally made of organic additives and a plastic binder.

CLEANINGthat step in the copy process during which residual toner particles, those left behind after image transfer, areremoved from the photoconductor; relies on mechanical systems to remove toner from the surface, and eithercontain it for disposal or recycle it in the development unit. (See also QUENCHING)

CLEANING BLADEthe secondary element in a copier's cleaning system; after a copy has been made, the cleaning blade acts like awindshield wiper, riding along the surface of the photoconductor to scrape off all remaining toner particles.

CLEANING BRUSHthe primary element in a copier's cleaning system; after a copy has been made, the round cleaning brushremoves most of the residual toner from the surface of the photoconductor. (See also BIAS ROLLER)

CLUTCHa control device for rotational movement; a clutch will either be engaged, locking its components together andtransferring rotation, or disengaged, letting its components turn separately and preventing the transfer of rotation.

CLUTCH, MAGNETICa type of clutch which contains its own electromagnetic actuator; when the clutch’s coil is energised, twometal plates are pulled together and transmit rotation to a given component-when not energised, the twoplates are separated by a spring, and no rotation is transmitted.

CLUTCH, SPRINGa popular clutch for copier applications; its internal components are normally held together by a spring connected to an external sleeve, and rotation is transmitted to a given component-when the sleeve is keptfrom turning, the spring expands, releasing one internal component and preventing the transfer of rotation.

36

G l o s s a r y

CORONA UNITa copier component that uses a high electrical voltage to create a localised electrical field of charged ions;various kinds of corona units are used at different points in the copy process.

CORONA WIREa thin wire, usually made from tungsten and coated with gold or carbon; mounted inside a corona unit, it carries the high voltage needed to generate an electrical field for a specific copier application.

CORONA, CHARGEa corona unit used for the first step in the copy process, to apply an even high-voltage charge to the photo-conductor; usually ventilated by a blower to help distribute ions during charging.

CORONA, PRE-CLEANINGa corona unit used at the end of the copy process; it creates an electrical field that reduces the charge on the photoconductor before mechanical cleaning, making it easier to remove leftover toner.

CORONA, QUENCHINGa corona unit used at the end of the copy process; it creates an electrical field to help remove latent imagecharge on the photoconductor after mechanical cleaning, preparing the surface for the next copy cycle;always used in conjunction with a quenching lamp.

CORONA, SEPARATIONa corona unit used immediately after Transfer; it creates an electrical field which releases the paper, togetherwith the developed toner image, from the photoconductor.

CORONA, TRANSFERa corona unit used immediately after Development; it creates an electrical field which pulls the developedtoner image away from the latent image on the photoconductor, transferring it to a sheet of paper.

CROSS MIXINGthe process by which toner and carrier are mixed together inside a copier; also creates and distributes the triboelectric charge that binds the toner to the carrier particles.

CURRENTthe rate of flow of electricity through a conductor; current is measured in Amperes, or Amps.

DEVELOPER, MONO-COMPONENTa special toner formulation that has both magnetic and electrical properties; functions without carrier.

DEVELOPER, TWO-COMPONENTthe most popular developer formulation; uses tiny, magnetic carrier beads to deliver much smaller toner particles to the photoconductor during the development process.

DEVELOPMENTthat step in the copy process which first produces a visible image on the photoconductor; during development,toner is applied to the photoconductor, where it is electrically attracted to the latent image formed during exposure.

DEVELOPMENT ROLLERpart of a copier's development system; relies on some combination of magnetism, triboelectric charge and/orbias voltage to apply toner to the latent image on the photoconductor.

DIFFUSION TRANSFERa photographic technique that uses a camera to produce an image on a special light-sensitive master; themaster is chemically developed and pressed against a transfer sheet, on which is produced a single high-qualitycopy of the original.

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DIGITAL METERan electronic instrument used to measure electrical voltage, current or resistance, which displays an individualreading as numerals on a LCD or LED display; good for showing specific measurements of circuit parameters with a high degree of accuracy. (See also ANALOGUE METER)

DIRECT CURRENT (DC)a type of electrical flow (current) which maintains a constant direction of travel according to a fixed polarity-DC flow is always from negative to positive.

DOCTOR BLADEpart of a copier's development system; limits the thickness of developer picked up by the development roller,by scraping off the excess as the roller turns; its precise position over the roller determines the height of themagnetic brush. (See also MAGNETIC BRUSH)

DOCMENT FEEDER, AUTOMATIC (ADF)a motorised device that allows automatic feeding, alignment and stacking of multiple originals, greatly improvingthe overall efficiency of photocopying; also known as an Automatic Document Handler (ADH).

DUPLEX UNITa paper-handling device that permits the making of two-sided copies without manual intervention by the user;available through the installation of a peripheral duplex unit on mid-size copiers, duplexing is a standard feature onmost high-volume machines.

E-STATan early electrostatic copy process; uses electrical charges to form and develop an image directly on chemically-treated, light-sensitive paper, using no intermediate photoconductor.

EDITOR BOARDa sophisticated copier peripheral that lets the user manipulate the latent image on the photoconductor; controls a group of erase lamps to remove selected parts of the image before development.

ELECTRICITYa form of energy consisting of electrons travelling at close to the speed of light in a suitable conductor, or present as a static field around an electrified object; can produce such effects as attraction, repulsion,heating and illumination.

ELECTRONthe smallest subatomic particle, existing in orbit around a nucleus composed of protons and neutrons; an atom normally has the same number of electrons as it has protons; when the number of electrons is eitherhigher or lower than normal, the atom gains an electrical charge and is said to be “ionised”. (See also ION)

ELECTROSTATIC CHARGEan electrical phenomenon in which a static (non-flowing) charge is created on an object or material by the presence of an electrical field; such a field is typically composed of ionised atoms and molecules spread out some distance from a source of electrical power. (See also ION, ELECTRON)

ERASE LAMPa component which removes certain parts of the latent image after exposure; after considering reproductionratio and paper size, the main control board turns on specific sections of the erase lamp to remove thecharge from the photoconductor outside the desired image area.

EXIT ROLLERSpart of a copier's paper feed system; a set of two rollers which push a finished copy from the fusing systeminto the exit or "copy" tray, outside the machine.

EXPOSUREthat step in the copy process that produces an invisible “latent” image on the photoconductor; can use lenses,mirrors, light guides and other components to produce a sharp and accurate copy.

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EXPOSURE LAMPpart of a copier's exposure and optical systems; provides the necessary illumination to create a reflectedimage from an original, which in turn creates an electrical latent image on the photoconductor; can be aquartz-halogen incandescent, fluorescent, or xenon flash design.

FEED ROLLERthe first roller to handle paper in a copier's paper feed system; pulls individual sheets from a paper supply,feeding them into the copier where they are passed to other rollers in the paper path.

FIBER OPTICa flexible glass or plastic fiber designed to conduct light like a wire conducts electricity; also refers to componentsand systems which utilise such fibers as an integral part of their function, as in “a fiber optic lens”; used in theexposure systems of some copiers. (See also LIGHT GUIDES)

FOCAL LENGTHthe characteristic of a lens that determines the distance at which it produces a sharply focused image; also determines the size of that image.

FOCUSthe characteristic of a lens or optical system that describes its ability to produce a clear and sharply definedimage; also refers to the adjustment of a lens or optical system to produce such an image.

FRICTIONa mechanical effect which causes surfaces in direct contact to resist moving in relation to each other; enablesan object whose surface is in contact with another object to affect that object's motion, even though the twosurfaces are not actually attached to each other; an important consideration in copier paper feed systems.

FRONT SURFACE MIRRORpart of the exposure system in most copiers; coated with metallic reflective material on the side facing intothe optical path, enabling them to produce sharp, high-resolution reflections suitable for optical use.

FUSINGthat step in the copy process that bonds toner to a sheet of paper; uses heat and pressure to melt toner andforce it into the paper surface, creating a copy that meets or exceeds the durability of the original.

FUSING LUBRICATION SYSTEMpart of a copier's fusing system, needed to keep toner from sticking to the fusing rollers; uses an absorbentpad and a blade to coat the rollers with silicone oil.

GRAY SCALEa row of small test patches showing a full range of image density, from solid black to paper white, usually in five to ten steps; printed on a copier test chart as a gauge of a machine's side-to-side and overall image density.

GRID PLATEpart of the charging system in copiers that use an Organic photoconductor (OPC); OPCs are more sensitive tohigh voltage charges, so the grid plate acts as a regulator between the OPC surface and the charge corona.

HOT ROLLERthe part of a copier's fusing system that contains the fusing heat source, usually an incandescent lamp; the hot roller is usually made of Teflon, and works in conjunction with the pressure roller.

IMAGE DENSITYthe quality of an original or copy that describes its relative lightness or darkness; high image density refers to a very dark copy, low image density refers to a very light copy.

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IMAGE DENSITY CONTROLthe system in a copier that compensates for the variation in reflectivity among different originals; some adjustthe brightness of the exposure lamp, others regulate toner transfer during development, by adjusting a biascircuit; in either case, image density controls can be manual, automatic or both.

IONan atom or molecule that has other than its normal number of electrons, causing it to have an electricalcharge; an atom that gains excess electrons has a negative charge and is known as a negative ion-an atomthat loses electrons has a positive charge: a positive ion; a localised cloud of ions constitutes an electricalfield. (See also ELECTRON)

JITTER BANDSlong bands of fine dots or lines printed on a copier test chart as a gauge of “jitter”, unsteady scanner or papermovement; white bands across the jitter bands indicate a sticking scanner-black bands mean unsteady papermovement during transfer.

LARGE CAPACITY PAPER TRAYa copier peripheral; holds a much greater amount of paper than a standard tray, thereby enabling the copierto run for longer periods without the supply being refilled; typically holds between 500 and 3,000 sheets.

LASERan acronym for Light Amplification through Stimulated Emission of Radiation, which refers to a device thatproduces an extremely accurate beam of coherent light; used in some copiers to “write” an image on the photoconductor, instead of reflecting and focusing one with conventional optics; very effective for producing a visual pattern from electronic information.

LATENT IMAGEa photographic term which refers to an undeveloped image on a piece of film; in xerography, it refers to the invisible, electrostatic image formed on the photoconductor during exposure.

LATERAL REVERSALan optical effect in which left and right perspectives are reversed, commonly perceived in the reflections frommirrors; a “mirror image” effect.

LEAD EDGEthe edge of a sheet of copy paper which first contacts the latent image on the photoconductor; the “frontedge” of a copy as it travels trough the paper path.

LEAD EDGE ERASEthe removal of that portion of a latent image which corresponds to a narrow strip along the lead edge of thecopy, usually no more than 5 mm wide; achieved through the action of an erase lamp immediately after theexposure process, to prevent a dark line from the edge of the original document from appearing on the copy.

LIGHT GUIDESbundles of glass or plastic optical fibers used in some copiers instead of a lens-and-mirror optical system;light guides are effective for exposure in a moving-platen copier, but are unsuitable for use with a movingscanner.

LIGHT SHOCKa condition that occurs in a photoconductor that has had prolonged exposure to ambient room light; cansometimes be corrected by a period of recovery time in darkness, but in severe cases can render the photo-conductor permanently insensitive to light.

LIQUID TONER TRANSFER (LTT)a process whereby the photoconductor drum is immersed in a shallow bath of liquid developer, from whichtoner particles are attracted to the latent image; the particles in liquid toner are much smaller than those indry toner, providing higher resolution on copies.

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MAGNETIC BRUSHa localised concentration of two-component developer formed on the surface of a development roller by magneticfields; brushes developer over the photoconductor during the development process, so that toner particles in thebrush can be attracted to the latent image.

MAGNETIC FIELDa localised area of influence surrounding a magnet or electric current, which manifests itself as a force on nearby magnetic or other iron-based objects; attracts all iron-based objects; attracts or repels magneticobjects depending on their orientation to the field.

MAGNIFICATION LINEStwo lines of an identical specified length, one vertical and one horizontal, printed on a copier test chart; used to check the vertical and horizontal magnification of a copier’s optical system.

MAIN CONTROL BOARDa printed circuit board containing the most important components in a copier's electronic control system,including the Central Processing Unit, and factory-programmed instructions stored on a Read Only Memorychip; the main board is linked to other parts of the control system with a number of multi-wire connectors.

MOVING PLATENa type of scanning optical system in which originals are placed on a glass document surface (the platen)which moves across a fixed exposure slit and lamp during an exposure; found only on relatively small, low-speed copiers.

MOVING SCANNERa type of scanning optical system in which originals are placed on a fixed glass document surface, underwhich is a moving lamp and mirror assembly (the scanner)-this scanner moves under the original during anexposure; found on most medium-to-high speed copiers; this design is also known as “fixed platen” scanning.

MULTIMETERan instrument designed to take a variety of electrical measurements for virtually any type of equipment;sometimes called a Volt-Ohm Meter or VOM. (See also ANALOGUE METER, DIGITAL METER)

ORGANIC PHOTOCONDUCTORa type of photoconductor based on certain organic chemicals, rather than metallic elements like selenium or silicon; requires negative charging before exposure; is generally non-toxic, enabling it to be handled anddisposed of more easily than selenium types.

OVER-TONINGa condition that occurs when a copier’s toner supply system is delivering too much toner to the developmentunit; the excess toner builds up inside the copier, especially around the photoconductor and paper path.

PADDLE ROLLERfound in a copier’s development unit; pushes charged developer (a mix of toner and carrier) against thedevelopment roller, which picks up the developer through magnetic attraction and brushes it over the latentimage.

PAPER CURLthe characteristic of paper that makes it tend to curve slightly in one direction, due to its original placement ona large roll during the manufacturing process; in a copier, paper should always be loaded with the curl awayfrom the photoconductor drum.

PAPER FEED SYSTEMthe various rollers, belts, sensors and control devices that are responsible for moving sheets of paper throughthe copier; begins with the paper supply, and ends with the exit tray or sorter that holds the finished copies.

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PARALLEL CIRCUITa type of electrical connection in which components each have a direct, independent path to a power source.(See also SERIES CIRCUIT)

PHOTOCONDUCTORa special material that reacts in certain ways to light and electricity, acting as an insulator in darkness and asa conductor when exposed to light; selenium is the most popular photoconductive material used in moderncopiers, although other organic and inorganic compounds are also used.

PHOTOINTERRUPTERSelectronic sensors that have a photocell and a Light Emitting Diode (LED) on either side of a small gap; when a tab on a moving component enters the gap, it blocks the light from the LED, shutting of the photocelland signalling the component's position to the copier's Main Control Board.

PICK-OFF PAWLSpart of a copier's separation system; providing a mechanical separation method, pick-off pawls ride along the surface of the photoconductor to peel off any paper not removed electrically by the separation corona.

POINT-TO-POINT DIAGRAMa kind of electronic map, specially designed for troubleshooting equipment with replaceable circuit boards;combines features of a schematic drawing and a block diagram, concentrating on connections to and fromdifferent components.

POLARITYthe quality of electricity that describes its tendency to exist in either a positive or negative state; in most electrical circuits, polarity determines the direction of current flow; in electrostatic charges, polarity indicatesthe charge of ions which make up an electrical field, and therefore determines the polarity of materials whichcan be attracted by that field-a charge of a given polarity always attracts materials of the opposite polarity.

POWERthe quality of electricity that measures its ability to perform work; also the specification of an electrical componentthat measures the amount of energy it consumes; power is measured in Watts.

POWER PACKa copier component that produces a very high DC or AC voltage needed to create an electrical field for a specificpart of the copy process; power packs are required for the charge, development, transfer and separation processes,and sometimes for cleaning; power pack output will vary in different copiers but is usually about 5,000 Volts.

PRE-TRANSFER LAMPused in some copiers to reduce the charge of the latent image after development, weakening its attractionjust enough to assure a clean transfer; also prevents toner particles from being attracted back to the photo-conductor during separation.

PRESSURE ROLLERpart of a copier's fusing system; during fusing, toner is forced into the surface of the paper by two rollers-thepressure roller and the hot roller; the pressure roller is usually made of silicon rubber, to help it withstand heatand provide a good grip on the paper. (See also HOT ROLLER)

QUENCHING CORONAfound in the cleaning and quenching system in some high-speed copiers; near the end of a copy cycle, it creates an electrical field which partially neutralises the pre-cleaning corona's charge on the photoconductor;always used in conjunction with a quenching lamp.

QUENCHING LAMPperforms the last process in a copy cycle: returning the photoconductor to an electrically neutral condition;shines light on the surface of the photoconductor to remove the latent image, after the leftover toner hasbeen removed by a cleaning brush and cleaning blade.

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RAG CONTENTa paper specification which indicates a certain amount of cotton fiber combined with the wood pulp fromwhich the paper was made; some more expensive copy papers have a 25% rag content.

REFLECTIONthat quality of light that describes its tendency to strike an object and bounce off at a predictable angle-theangle of the incidence always equals the angle of reflection; mirrors are used in most copier exposure sys-tems to control light by reflecting it in different directions.

REFRACTIONthat quality of light that describes its tendency to bend as it passes through a transparent material; a lens isused in most copiers to focus an image by bending its individual light rays a specific amount in the desireddirection.

REGISTRATIONthe process by which paper is lined up properly with the developed image on the photoconductor; registrationis usually accomplished with a system of rollers, mechanical guides and electronic sensors.

REGISTRATION MARKSprinted at the top and side of a copier test chart as a gauge of paper alignment and copier erase margins;consist of thin parallel lines that will show if the paper is improperly meeting the latent image on the photo-conductor.

REGISTRATION ROLLERSpart of a copier’s paper feed system; a pair of rollers which align a sheet of paper with the latent image, andthen feed the sheet toward the photoconductor at the correct time during the copy cycle.

REGISTRATION SENSORpart of a copier's paper feed system; an electronic sensor mounted in the paper path just before the registrationrollers; alerts the copier’s control system when a sheet of paper approaches the rollers, so that they can bestopped before the sheet contacts them.

RELAY ROLLERSpart of a copier's paper feed system; used in machines with long or complex paper paths simply to movesheets from one area to another-they have no special copy-related function.

REPRODUCTION RATIOan optical specification that determines the relationship between original size and copy image size; a one-to-one reproduction ratio indicates that original and copy have the same image size; can be varied in somecopiers to produce enlarged and reduced copies.

RESISTANCEthat quality of an electrical conductor that measures the degree to which it opposes a flow of electricity;resistance is measured in Ohms.

RESOLUTION BARSprinted on copier test chart as a gauge of the overall sharpness of a machine's optical system; should beclearly visible on copies as individual lines.

SCANNERpart of the exposure system in a moving scanner copier; these exposure systems have two scanners-the first consists of a light-weight metal frame containing one mirror and the exposure lamp-the second has a similar frame and two mirrors; both scanners move along guide rails during an exposure, and reflectthe image between them during the scan to maintain a constant optical distance from the original to the lens.

SCHEMATIC DIAGRAMthe most traditional and detailed type of electronic map; shows every circuit no matter how complex, and every component, no matter how small.

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SELENIUM DRUMthe most popular photoconductor design; consists of a hollow aluminium cylinder coated with several layersof material: aliminium oxide, selenium and selenium oxide; the selenium layer provides the key photoconductiveproperty of having high electrical resistance in the dark, and low resistance when exposed to light; the drum shapeallows the surface to interact easily with other copier components.

SEPARATIONthat step in the copy process during which the paper and toner are separated from the photoconductor; usually accomplished by a separation corona unit, sometimes assisted by mechanical pick-off pawls.

SEPARATION PADa cork pad used to provide friction for separation sheets of paper during an unwanted multiple-feed; found ina copier's paper feed system, and also in Automatic Document Handlers.

SERIES CIRCUITa type of electrical connection in which components share a common path to a power source. (See also PARALLEL CIRCUIT)

SERVO MOTORused in many copiers to move scanners in the optical system; servo motors emit a specific number of electricalpulses with each revolution, allowing a control circuit to monitor and regulate their speed.

SETTING POWDERa dry lubricant powder applied to new photoconductors immediately before installation; during initial operation, the powder protects the surface from scratches which might result from contact with other copier components.

SOLENOIDa simple electrical control device, consisting of a hollow electromagnet and a metal plunger; when the magnetis energised the metal plunger is pulled inside it, triggering whatever mechanism is attached.

SORTERa paper handling device that feeds finished copies into multiple output bins; can produce “sets” of collatedcopies, which match the order of the original documents, or count out “stacks” of single copies.

STEPPER MOTORa type of electric motor designed to be controlled in individual steps which are portions of a full rotation, eachstep as small as one degree of arc; often used to adjust lens position in copiers with variable reproductionratio, a stepper motor’s design allows for extremely precise lens placement and easy electronic control.

STRIPPER FINGERSpart of a copier's fusing system; stripper fingers ride along the surface of the hot roller, and peel off copiesthat stick to the roller despite the roller's lubrication.

TELLURIUMa material used as an additive in selenium-based photoconductors; hardens the photoconductor's surfaceand improves its ability to copy blue image areas.

TEST-CHARTa specially designed copier original, with printed gauges used to assess many aspects of copy quality.

THERMISTORa heat-sensitive electronic component, used in a copier’s fusing system; indicates changes in temperature by varying its electrical resistance, allowing the main control board to monitor and regulate the fusing temperature.

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THERMOFAXa copying system based on heat; in Thermofax, an original is created with heat absorbing ink; this original isthen exposed to high temperatures, making it hot enough to burn an image of itself into special heat-sensitivepaper; an early process, it is now used only for making overhead projector transparencies.

THERMOSWITCHan electrical control device used in copiers as a form of overheat protection for the exposure system; if the thermoswitch is exposed to a certain high temperature, it opens and shuts off the exposure lamp; after sufficient cooling has taken place, the switch closes and operation may continue.

TONERthe “ink” of an electrostatic copier which forms the actual image on finished copies; made from resin and asolid lubricant combined with carbon or a coloured pigment; toner is not magnetic, but is bound to carrier particles by a triboelectric charge, creating two-component developer. (See also TRIBOELECTRIC CHARGE)

TONER-END SENSORpart of a copier’s development system; an electronic sensor which monitors the level of toner in the tonersupply-when the sensor detects a predetermined “low-toner” condition, it signals the control system, whichthen lights a corresponding indicator on the machine's operation panel; usually detects two different toner levels: “low” and “too low to continue operation”.

TONER-OVERFLOW SENSORpart of a copier’s cleaning system; an electronic sensor which monitors the level of toner in the used-tonerstorage tank-when the sensor detects a predetermined “used-toner tank full” condition, it signals the controlsystem, which then lights a corresponding indicator on the machine’s operation panel; usually detects two different toner levels: “full” and “too full to continue operation”.

TONER SHIELD GLASSa piece of ordinary glass used in copiers as a “window” in the exposure slit; allows light to reach the photo-conductor, but keeps toner from contaminating the optical system.

TONER-ADD SYSTEMa combination of electronic and mechanical components that monitors the average density of toner on the photoconductor, and adds toner to the development unit whenever the density falls too low.

TRANSFERthat step in the copy process in which toner, held by the latent image on the photoconductor, is transferred to a blank sheet of paper, thereby creating a copy; is usually accomplished with a Transfer Corona Unit.

TRANSPORTthe primary job of a copier’s paper feed system: moving sheets of paper from the supply, through the machine, and out into the exit tray; accomplished with a variety of rubber belts and rollers.

TRAPPING LAYERthe surface layer of a selenium photoconductor, composed of selenium oxide; receives and traps an electrostaticcharge on the surface as long as the photoconductor is in darkness.

TRIACan electrical control device, similar to a transistor but able to control very high power levels directly; used toregulate exposure lamp and fusing lamp voltages in most copiers.

TRIBOELECTRIC CHARGEa type of static charge that builds up when certain materials are rubbed together; a triboelectric charge isused to attract toner to carrier in a two-component developer system.

UNDER-TONINGa condition that occurs when a copier’s toner-supply system is delivering too little toner to the developmentunit; can lead to carrier abrasion, which may damage the photoconductor and shorten the useful life of thecarrier particles.

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VERIFAXan early copying system developed by Eastman Kodak Company; photographed an original using a “master”which was chemically developed into an image of hard areas and sticky areas; the developed material wasthen pressed against special paper-the sticky areas adhered to the paper, producing about ten copies fromevery master.

VOLTAGEthat quality of electricity that measures the force with which it moves through a conductor; also known asElectro-Motive Force (EMF), voltage is measured in Volts.

XEROGRAPHYthe indirect electrostatic copying system which is the basis of all modern plain paper copiers; patented in1939 by Chester Carlson, Xerography comes from the Greek words for “dry writing”.

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