IJ Basic Training

RKC London Office

Printing world and history

Classification for printersWe can classify printers by various point of view

Classification Outline

Colour or Monocolour or

B/W

Impact or Non impact

Difference of whether the machine apply pressure when ink transfer onto the paper.Impact printer is mainly used for NCR paper of parcel etc.

Page printer or Serial printer

Page printer will print per page, serial printer will print per line.Currently electro photography printer typify page printer, dot impact printer typify serial printer.

Postscript or GDI printer

Difference of how to create the page image.Adobe PS is standard in DTP market.

USB or Parallel or LAN or SCSI

Classification from how to connect with PC.In the office environmental, LAN is most popular connection.Some printers have particular connection such as IrDA, Wi-Fi .

Difference of print system

Category Outline

Dot impact As for printer from PC, Dot impact system is mainly used in around 1990

Thermal Transfer Around 1990, “word processor” with printer is more general than PC in family use. Thermal transfer system is basically used on word processer.

Xerography(Electro photography)

Cyanotype photo copier is not used recentlyPPC (Plane Paper Copier) is general photo copy system in the officePPC is called electro photography copier

Inkjet Recently almost domestic used printer is inkjet printer

Silver halide print It is used same system with film photo“Pictrography” from Fuji Film is famous product

There are various kind of system for printers

Dot impact printer

MechanismThe head has 24 to 48 fine pins witch is driven by solenoid. Ink ribbon is sat between the paper and the head, when the pin will impact the ink ribbon, ink will transfer onto the paper.

FeatureEnable to print with non carbon paper.It needs replace the ink ribbon.Print noise is high.Mainly it is used for continuance paper with punch by tractor mechanism.Unable to print full colour.

Solenoid

Pin

Ink ribbon

Paper

Heat transfer printer

MechanismThe ink ribbon is placed between the thermal head and the paper, when the head is heated, melted ink will transfer onto the paper.The thermal head has many heat elements, printer will drive the each elements.

FeatureHigh running costPrint noise is low levelBasically print speed is slower than page printer, especially full colour.Some product can print with gold or silver colour with special ink ribbon.

Xerographic printer (electric photography)

MechanismThe toner will adhere on the drum by static electricity, then the toner will transfer onto the paper. The toner will fix by the heat roller.To make static electricity image on the drum, laser or LED are used.laser used machine is called LBP(laser beam printer)LED used machine is called LED printer

FeatureGenerally power consumption is highThe paper might be curled due to the heat roller.When replace the toner, there are type of the cartridge with drum together and only toner cartridge.

General print quality Dye-sublimation printers Inkjet (domestic used) LBP

Drum

Toner

Laser

Heat roller

2 kinds of xerographic colour printer

MechanismThere are two kind of system for colour printer, “4 cycle system” and “Tandem system”.For 4 cycle machine has one exposure and drum, other hand tandem’s one has four units for each colour.Tandem system usually transfer the toner onto the belt, after that the belt will rotate to print on the paper.Canon PXCEL doesn’t have a belt, enable to print directly by precise position control.

FeatureTandem system is favorable for high speed print.

Inkjet technology

Inkjet printer

OutlineThere are two kind of inkjet system piezoelectric (Epson) and thermal jet system.(HP, Canon and Lexmark )Generally space between the head and the paper is 1 to 3mmMainly there are two kind of inkjet ink, “Dye type ink” and “Pigment type ink”.For domestic used inkjet printer, basically water base ink is used.

FeaturePrint head is quite delicate and week for some dust.Inkjet system has wide application as technically.

Classification of Inkjet system

CIJ(continuous inkjet)

Line head

Serial headPiezoelectric

Thermal jetDOD

(drop on demand)

vs.

vs.

vs.

RISO

Basis of Inkjet technology

In the 1950sStart industrialization as some kind of record technologies

In the 1960sLaunch the continuous inkjet system

In the 1970sLaunch the on-demand inkjet system by piezoelectric element

In 1979Thermal inkjet system is developed

After 1980In the domestic used market, the product get around quickly as desk side printer

Comcolor adopt on-demand type inkjet system

CIJ (Continuous Inkjet)

OutlineWhen start the print, the head drop ink continuously.If the electrode works, ink will turn to the paper, un-used ink will be collected to re-use.

FeatureUsing quick-drying ink is available because of it drop ink continuously so that misfire is difficult to occurThe distance between the head and the target is generally wide from 5 to 50mmIn the factory, to print the “days”, “Lot No” onto the cardboard box, cans, bottles etc.

Electrode

Collect

Target

Ink

DOD (Drop On Demand)

There are thermal system and piezoelectric system for DOD system.

The head has many nozzles according to target of print quality.

The distance between the head and the paper is around 1mm.

Basically used for printing on the paper.

Thermal Jet

When the heater evaporate inside ink, ink will come out from nozzle by pressure from the head.System is very simply, so it is easy to make it high resolution head.Basically only water base ink is available because of vaporization system.It is difficult to control the volume of drop ink.

1mm

Ink Drop

Ink Refill

Cavitation

Bubble

　　 Heater

　　　Ｉ nk

Meniscus

Paper

Piezoelectric Actuator

Piezoelectric is one of the electric element witch is moved by small electricity.Ink dropping volume can control both analog and digital.Analog: amount of piezoelectric movementDigital: number of dropping = 8 level gradation

FeatureBoth water base ink and oil base ink are available.It is complicated system and a little difficult to level up the resolution.

Nozzle Plate

Nozzle

Electrode Piezoelectric

Ink Drop

Piezoelectric vs. Thermal jet

Feature Piezoelectric Thermal jet

Ink ejection Head vibration (Mechanical)

Bubble in ink Thermal jet will burn with aging by heat element

Head cost High Low Piezo needs assembly process

Head durability ◎ △

Head (High) DPI High cost Low cost Difficult to downsize Piezo actuator

High frequency drive Controllable A little difficult Thermal jet heat up easily

Energy efficiency ◎ × 5 to 10 times than Piezo

Range of ink drop volume

Wide (10 times) Narrow (2 to 3 times) Piezo can adjust physically

Ink Oil / Water Water

Ink drying ○ / × ×

Wave of paper ◎ / × × Stable duplex paper feeding

Finishing ○ / × × Low level wave of paper

Print speed ◎ / △ △ Low level wave of paper

Print quality △ / ◎ ◎

RISO

Misfire and head cleaning

Necessary to clean the headIf it doesn’t print for long time Ink on surface of the head will dry up Nozzle will clog up with dry up ink

For domestic used inkjet printerThe head is usually cleaned at head home position.After printing, the head will covered with the cap to prevent ink dry up.Before printing some machine perform blind dropping (compulsory ink dropping) and wiping.Basically it has sponge to absorb the waste ink

Serial printer and Line printer

Low Print speed High

Serial print head

The print head will drop with moving main scanning direction.After printing width of the paper, the paper will be conveyed as established amount.Recently due to realization for high speed print, some machine can print when the head return to home position too.

Serial head can be double dropping, high resolution print is available.If misfire will occur, it does not stand out, but this system has handicap for high speed print.

Four colour serial head

Six colour serial head

Mechanism of serial head printer

Head size (width) is small, around from 0.5 to 1 inch and low cost, basically ink cartridge is placed above the head.

Regarding the dot size of the head, it became to small one tenth in 6 years so quickly.

Wide-format inkjet printer (Poster printer) is also used serial head system.

Line print head

RISO use the line print head system.It has 24 print heads in the system, they does not move, just it has paper feeding mechanism.It unable to be high resolution print by double dropping such as serial head print system.If misfire will occur, it will stand out a little.

Paper

Print head

Paper feed

Inkjet ink

Water based dye type ink

Dye type ink is that coloring material (dye) dissolve into the water base liquid.This coloring material is quite small. (less than 1nm)Dye ink is seen through liquid.Paper waving will occur easily.Generally light resistance and water-proof are inferior.Recently there are also water based pigment ink to solve above weaknesses.

Oil based pigment type ink

Pigment ink is that color material (pigment) mix with oil base liquid.Size of this coloring material is around 1μm.This size is about 1000 times from dye material but don’t deposit.Pigment ink is turbid liquid.As for light resistance and water-proof, generally better than dye ink.And also as for paper wave, it is better than dye ink.Output document has some particulate image.The head clog up with ink easily compare with dye ink.

Dry up mechanism

Soak Evaporate

Fiber of paper will swell

Then paper will have wave easily

Water based ink

Oil based ink

Solvent ink

Soak Diffuse

Fiber of paper will not have damage.

Evaporate Fuser

Various base material will be compatible.

Ink

Bleeding

Show through

Ink layer

Base material Keep the ink

RISO IJ ink and paperNormal paper Coated paper

Paper

Coated paperDry up image is similar to “Silica gel” Ink will soak into the porous layer and fixBasically porous silica is used for coat materialQuick dry upWater proof (depends on ink)Both dye and pigment ink are availableHigh costDifficult to make glossy paper

Porous particle type

High polymer type The image of paper is “disposable nappy”Special resin which is dissolved is coated on the paper.When ink is dropped down, the resin will expand and then ink will fixLow costPigment ink is not available The image will blot by water

Porous silica

Expand and fix

Resin

Soak and fix

Glossy paper

Paper based

Photo based

Photo based

Porous particle type

High polymer type

Low cost (paper based material)High absorbentWater proof (depends on paper)It change base white color a little easily

High cost (both photo base and coat material are expensive)High quality print is availableWater proof (depends on paper)Manufacture is difficultIt change base white color a little easily

Base material is a little expensive but coat material is low costManufacture is easyWaterproof is inferiorIt is hard to change base white color

Paper

Photo paper

Photo paper

Acceptance layerGlossiness layer

Glossiness and acceptance layer

Glossiness and acceptance layerPE

PE

RISO IJ technologies

Meniscus shape of ink

In the inkjet print head, ink have to keep meniscus shape at top of the nozzle.To keep this shape, it is used pressure of atmosphere and interfacial forceIf the head cannot make the meniscus, ink cannot drop correctly or drip down without printing.

Meniscus

RISO Print head

Each ink room in the head is built by piezoelectric element, so that it is easy to design high resolution print head.

The piezo element will work inhale and drop ink both, so that the next nozzle cannot drop at same time.

The nozzles are arranged diagonally three nozzles each.

Print head layout for comcolorRISO IJ printer has total 24 heads which are arranged above the transfer belt accurately.Space between each color is about 110mm for HC, 67mm for comcolor.

Image for ink droppingRiso piezo head can control 8 level image gradation by number of dropping.(Actually it is used five kind of drop level to print, 0, 4, 5, 6, 7 drops)One drop is 6pl ink each.Just before ink touch onto the paper, dropped ink will gather as one drop.

30pl(5x6pl)

6pl 18pl(3x6pl)

20μm

Ink drop

Just before ink touch on the paper, dropped ink will gather as one drop by air resistance

MF, MD and MistMis-fire(MF)If the head nozzle is closed completely by old ink or Paper dust, ink cannot drop correctly, then white line will occur.

Mis-direction(MD)If the head nozzle is clogged a little, ink cannot drop straight, then slight white line will occur.Usually surface of the head has oil repellent finish. If the ink remain on the surface of the head, ink cannot drop correctly.

MistIf the ink cannot drop onto the paper, ink will stain another part in the machine.The gap between the head and the paper is around 1mm, so if the gap will be expand, ink mist will occur easily.

Oil repellent

Mist

Resolution

If select the resolution to 300x600dpi on the printer driver, the resolution of paper feed direction will be twice.Then print speed is slower than 300x300 dpi mode.

Piezo head can control the ink drop size so that if select the line smoothing, high quality print is available near double resolution .

Paper feed

Paper feed

300dpi

300dpi

600dpi

Properties of RISO IJ ink 1

RISO select oil based pigment ink, when drop onto the paper, ink will soak into the paper and fix.Some domestic used glossy paper or OHP sheet are not compatible.RISO ink is not “volatile ink”, so ink material will remain in the paper.

Drop

Soak

Fix

Properties of RISO IJ ink 2When the printed document is covered by plastic material such as PP or PE, the cover might be curled by ink ingredients.PP or PE will expand with IJ ink ingredientsWhen the customer place on the printed document on the desk or insert into the plastic bag, slight printed image might transfer to the desk or plastic bagFor PET resin will not occur with these symptom.

PP: PolypropylenePE: PolyethylenePET: Polyethylene terephthalate

Slight image

Curl

Properties of RISO IJ ink 3

If the printed documents are rolled by rubber band or covered by thick tape, the image on top of the paper (outside of paper) might have trace line image with rubber band or thick tape due to bump pressure.If the customer have to cover the paper, it is effective to insert another white paper between band and the printed documents.

Trace line image

Bump pressure

Properties of RISO IJ ink 4When the customer wrap printed document by wrapping paper, some oily ingredient will come from the wrapping paper. Because the wrapping paper usually has waterproof film on backside of the wrapper, then some ink ingredients might melt down it.It is efficiency to insert the another paper between wrapping paper and printed documents.

Wrapping paper

Another white paper

Printed documents

Properties of RISO IJ ink 5Depends on the situation, the PPC documents might stick each other or the toner might come off from the paper.When the PPC documents and IJ printed documents are mixed, especially for high density IJ print, the toner will melt down and stick to another paper easily.Both situation, IJ print and PPC print “face to face” or same direction, it symptom will occur.When the customer write figure on the IJ printed document by oil based pen, the printed image might blot. So it is efficiency to use water based pen for IJ printed material.

Face to face

Same direction

Properties of RISO IJPaper curlIf the paper has some curl, paper might touch to the print head. So it has some mechanism to detect the paper curl.Ink mark with edge of the paperWhen print solid and quite wide area a lot, ink might stain on edge of the paper. Especially when using envelope, it symptom will occur easily.Ink mark on the back side of paperWhen duplex printing, some ink might stain on the switch back roller. So back side of paper will stain as roller mark.A3 size printingUnder the cold environmental under 20 degree, A3 thick paper feeding from tray1 might be mis-feed. It is better use the standard tray or tray2 or tray3.Don’t shake the ink cartridgeIf the cartridge is shaken, some air babble will be mixed in the ink, then it might be cause of the white line.The temperature controlWhen the Ink jet ink is cold, mis-direction will occur easily due to viscosity will be high condition, so the machine has temperature control mechanism.

Difference in fluid levels 1

Meniscus

Difference influid levels

Atmospherepressure

Ink flow

Atmospherepressure at

nozle

Generally when ink face atmosphere, ink receive same air pressure at each position. In this situation, ink will flow from high position to lower position.This difference is called “Difference in fluid levels”

To keep meniscus shape of ink at the nozzle, basically this principle is used on RISO IJ system.

The head nozzle is quite thin, so ink will not flow down quickly, then it can keep the meniscus at the nozzle.

Difference in fluid levels 2

Pressureair

Regarding the left figure, in the closed situation, the principle of “difference in fluid levels” is not applicable.Then ink does not flow to ink tank even if the ink tank is lower position than the nozzle.

If ink tank is pressured by pump, ink will flow to left side, then ink drop down from the nozzle.

Difference influid levels

closed

Ink tank

JIG for maintenance

Tube clamper

5.5mm box driver

Front door sw maintenance connector

Print Head attachment

For the details, it is mentioned on the technical training