capacitive touch screens nfees

7/25/2019 Capacitive Touch Screens nfees

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CAPACITIVE TOUCH SCREENS

One of the more futuristic applications of capacitors is the capacitive touch screen.

These are glass screens that have a very thin, transparent metallic coating. A built-

in electrode pattern charges the screen so when touched; a current is drawn to the

nger and creates a voltage drop. This eact location of the voltage drop is pic!edup by a controller and transmitted to a computer. These touch screens are

commonly found in interactive building directories and more recently in

Apple"s i#hone.

Touch-screen monitors have become more and more commonplace as their price

has steadily dropped over the past decade. There are three basic systems that are

used to recogni$e a person"s touch%

&esistive

'apacitive

(urface acoustic wave

The resistive systemconsists of a normal glass panel that is covered with a

conductive and a resistive metalliclayer. These two layers are held apart by

spacers, and a scratch-resistant layer is placed on top of the whole setup. An

electrical current runs through the two layers while the monitor is operational. )hen

a user touches the screen, the two layers ma!e contact in that eact spot. The

change in the electrical eld is noted and the coordinates of the point of contact arecalculated by the computer. Once the coordinates are !nown, a special driver

translates the touch into something that the operating systemcan understand,

much as a computer mousedriver translates a mouse"s movements into a clic! or a

drag.

*n the capacitive system, a layer that stores electrical chargeis placed on the

glass panel of the monitor. )hen a user touches the monitor with his or her nger,
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some of the charge is transferred to the user, so the charge on the capacitive layer

decreases. This decrease is measured in circuitslocated at each corner of the

monitor. The computer calculates, from the relative dierences in charge at each

corner, eactly where the touch event too! place and then relays that information to

the touch-screen driver software. One advantage that the capacitive system has

over the resistive system is that it transmits almost percent of the lightfrom themonitor, whereas the resistive system only transmits about /0 percent. This gives

the capacitive system a much clearer picture than the resistive system.

On the monitor of a surface acoustic ave system, two tra!s"ucersone

receiving and one sending2 are placed along the and y aes of the monitor"s glass

plate. Also placed on the glass are re#ectors-- they re3ect an electrical signal sent

from one transducer to the other. The receiving transducer is able to tell if the wave

has been disturbed by a touch event at any instant, and can locate it accordingly.

The wave setup has no metallic layers on the screen, allowing for 1-percent light

throughput and perfect image clarity. This ma!es the surface acoustic wave system

best for displaying detailed graphics both other systems have signicant

degradation in clarity2.

Another area in which the systems dier is in which stimuliwill register as a touch

event. A resistive system registers a touch as long as the two layers ma!e contact,

which means that it doesn"t matter if you touch it with your nger or a rubber ball. A

capacitive system, on the other hand, must have a conductive input, usually your

nger, in order to register a touch. The surface acoustic wave system wor!s much

li!e the resistive system, allowing a touch with almost any ob4ect -- ecept hard and

small ob4ects li!e a pen tip.

As far as price, the resistive system is the cheapest; its clarity is the lowest of thethree, and its layers can be damaged by sharp ob4ects. The surface acoustic wave

setup is usually the most epensive.

Ho the iPho!e $or%s
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*n 6anuary +/, (teve 6obsintroduced the Apple i#hone during his !eynote address

at the 7acworld 'onference and 8po. *n its rst appearance onscreen and in 6obs"s

hand, the phone loo!ed li!e a slee! but inanimate blac! rectangle.

Then, 6obs touched the screen. (uddenly, the featureless rectangle became an

interactive surface. 6obs placed a ngertip on an on-screen arrow and slid it from left

to right. )hen his nger moved, the arrow moved with it, unloc!ing the phone. To

some people, this interaction between a human nger and an on-screen image --

and its eect on the i#hone"s behavior -- was more ama$ing than all of its other

features combined.

And those features are plentiful. *n some ways, the i#hone is more li!e a palmtop

computer than a cellular phone. As with many smartphones, you can use it to ma!e

and receive calls, watch movies, listen to music, browse the )eb, and send and

receive e-mail and tet messages. 9ou can also ta!e pictures and video using an

i#hone 5:( or later model2 with a built-in camera, import photos from your

computer and organi$e them all using the i#hone"s software.

*n +, Apple introduced the second generation i#hone. This i#hone operates on

third-generation 5:2 cellular networ!s and has a :#( receiver. *t also lets you view

map and satellite data from :oogle 7aps, including overlays of nearby businesses.

Owners of the original i#hone got the opportunity to upgrade the software on their

phones. The +. software gave the old phones new functions, but without the :#(

receiveror 5: networ! capability.

+ was the year that Apple launched the i#hone 5:(. The 5:( i#hone models

have more storage capacity than earlier i#hones. They also have a better camera

that"s capable of ta!ing still shots and video at 5 frames per second. Another

added feature is a compass, which comes in handy when you need to nd your way

through unfamiliar territory. Also in + came i#hone O( 5., which oered many

improvements, such as the ability to cut and paste.

*n +1, (teve 6obs too! the stage to announce a new generation of Apple"s

runaway success% the i#hone


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uire you to touch multiple points on the screen simultaneously. @or

eample, you can $oom in to )eb pagesor pictures by placing your thumb and

nger on the screen and spreading them apart. To $oom bac! out, you can pinch

your thumb and nger together. The i#hone"s touch screen is able to respond to

both touch points and their movements simultaneously. )e"ll loo! at eactly how

the i#hone does this in the net section.

Apple"s iO( lets you interact with all of the applications on your i#hone. *t displays

icons for each application on the i#hone"s screen. *t also manages battery power

and system security. The operating system synchs the phone with your computer on

older i#hones and iO( versions, a process that re>uires a connector much li!e the

one used to synch an i#od, but since iO( 0, most synching of data across Apple

devices can ta!e place via the new i'loud service. The O( also lets you multitas!

and move through multiple open applications, 4ust li!e you can on a laptop or

des!top computer.

ut instead of using a mouse or a physical !eyboard, the i#hone uses virtual buttons

and controls that appear on its screen. This isn"t really a new phenomenon -- touch

screens have been part of everything from self-chec!out !ios!s to smartphones for

years. ut the i#hone"s touch screen is a little dierent from many of the otherscurrently on the mar!et. )hen you touch the screen on a #BA or a Cintendo B(, you

typically use a slender, pointed stylus. The i#hone, on the other hand, re>uires you

to use your ngers or a conductive stylus. *t can also detect multiple touch points

simultaneously.

This article will eplore eactly how the i#hone"s touch screen carries instructions

from your ngertips to the phone"s internal circuitry. )e"ll also loo! at the features
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in Apple"s latest and greatest, the i#hone 0c and 0s, and the +15 update to its

operating system% iO( /.

The ma!y compo!e!t layers i! a mutual capacita!ce scree!)

*ulti+touch Systems

To allow people to use touch commands that re>uire multiple ngers, the i#hone

uses a dierent arrangement of eisting technology. *ts touch-sensitive screenincludes a layer ofcapacitivematerial, 4ust li!e many other touch screens. Dowever,

the i#hone"s capacitors are arranged according to a coordinate system. *ts circuitry

can sense changes at each point along the grid. *n other words, every point on the

grid generates its own signal when touched and relays that signal to the i#hone"s

processor. This allows the phone to determine the location and movement of

simultaneous touches in multiple locations. ecause of its reliance on this capacitive
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material, the i#hone wor!s only if you touch it with your ngertip -- it won"t wor! if

you use a stylus or wear non-conductive gloves.

The i#hone"s screen detects touch through one of two methods% 7utual capacitance

or self capacitance. *n mutual capacita!ce, the capacitive circuitry re>uires two

distinct layers of material. One houses driving lines, which carry current, and theother houses sensing lines, which detect the current at nodes. Self

capacita!ceuses one layer of individual electrodes connected with capacitance-

sensing circuitry. oth of these possible setups send touch data

as electricalimpulses.

The +1+ i#hone 0 replaced the previous touch screen with an in-cell touch

screen that still uses capacitive multi-touch technology, but combines the

capacitive touch sensing layer and the E'B

The iPho!e&s touch scree! registers your touch a!" co!verts that ra "ata

i!to precise coor"i!ates)

iPho!e Processor Touch I!terpretatio!

The i#hone"s processorand software are central to correctly interpreting input from

the touch screen. The capacitive material sends raw touch-location data to the

i#hone"s processor. The processor uses software located in the i#hone"s memory to

interpret the raw data as commands and gestures. Dere"s what happens%
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I! the !a!oseco!" 'etee! the time you touch the iPho!e&s scree! a!"

the "isplay reacts, several calculatio!s a!" sig!als are se!t from the

touch scree! to the softare)

1. (ignals travel from the touch screen to the processor as electrical impulses.

+. The processor uses software to analy$e the data and determine the features of

each touch. This includes si$e, shape and location of the aected area on the

screen. *f necessary, the processor arranges touches with similar features into

groups. *f you move your nger, the processor calculates the dierence between the

starting point and ending point of your touch.


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5. The processor uses its gesture-interpretation software to determine which

gesture you made. *t combines your physical movement with information about

which application you were using and what the application was doing when you

touched the screen.


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i#hone 0s model ups the sta!es with an -megapiel camera. 9ou can also use an

i#hone to chec! weather reports and stoc! >uotes. 8ven though the i#hone doesn"t

support @lash, which 9ouTube"s non-mobile site relies on, you can watch 9ouTube

videos using the corresponding application. An Apple version of 9ouTube was built in

prior to iO( ?. Cow the iO( re>uires that you download either the :oogle 9ouTube

app or another video search and play app that can access 9ouTube. The virtual !eysand buttons you need to navigate each application appear only when you need

them.

The shape of the screen changes when you need it to as well -- you can shift the

perspective from vertical to hori$ontal by tilting the phone. An accelerometer inside

the i#hone lets the operating system !now to change the orientation of the image

on the screen. This means that you can scroll through long lists of music les on a

long, narrow screen, and you can watch movies in a widescreen format. 9ou can

learn more about accelerometers in

Other physical buttons and switches, aside from the Dome button, are locatedaround the edge of the phone. An onFo or sleep button is located at the top of the

phone. A switch on the left side lets you set your phone from ringing to silent, and

4ust below that are the volume buttons.

./ iPho!e Applicatio!s a!" Pro'lems

*n 6une +, (teve 6obs unveiled the 5: i#hone at a conference for application

developers. Appleoered and 1? : options of the 5: edition of the i#hone. The

phone"s appearance only changed a little bit -- this model has a slightly slee!er

design and its bac! isn"t silver. 'ustomers who bought the 1? : model could

choose between an i#hone with a blac! or white plastic bac!. The : model wasonly available in blac!.

#erhaps the biggest announcement -- apart from the fact that the phone could ta!e

advantage of 5: networ! technology -- was that the 5: i#hone had a :#( receiver.

One of the challenges of :#( devices is that they tend to drain batteries pretty

>uic!ly. That"s because the device is constantly receiving signals from satellites

orbiting the 8arth.

Another important addition to the i#hone was support for 7icrosoft 8change.

7icrosoft 8change support means users can now synchroni$e their i#hones with

their 7icrosoft Outloo! accounts. y adding this feature, the i#hone became morecompetitive with other enterprise smartphones -- the phones businesses use to

!eep eecutives and employees connected when out of the oGce.

)hen it released the original i#hone, Apple didn"t support third-party applications,

though that didn"t stop developers from writing them. ut with the original i#hone,

in order to even run a non-Apple application, an i#hone owner had to

rst4ailbrea!his or her phone. 6ailbrea!ing 4ust meant the owner could load and run
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third party applications. ut it came with a ris! -- if you tried to install oGcial

updates from Apple with a 4ailbro!en phone, Apple could tell that some han!y pan!y

was going on. ut the 5: i#hone acts as an application platform, and Apple

encourages developers to create content for it.

The transfer to the 5: i#hone didn"t go without a hitch. *nstead of allowingcustomers to purchase phones and activate them at home, Apple wanted them to

activate the phones inside the store. Hnfortunately, Apple"s systems suered an

overload, causing massive delays during the product launch. 7ost customers ended

up having to activate at home anyway.

(ome of the new applications that became available when Apple opened up

development for the i#hone ta!e advantage of the device"s accelerometer feature.

:ames li!e I(uper 7on!eyallI let the player control the game character by tilting

the phone in dierent ways. 'ould the i#hone become the net portable gaming

platformJ That"s precisely what Apple claimed at its (ept. , + press event. That

brings us up to the i#hone 5:(.

APP CONTROVERS0

To get an application into the iTunes App store, Apple must approve it rst. Apple

retains the right to deny any application that duplicates or damages the features of

the i#hone. This has led to controversy -- in +, the @'' stepped in to investigate

claims that Apple re4ected :oogle Koice applications unfairly.

iPho!e ./S

Apple unveiled the i#hone 5:( at the + )orld )ide Bevelopers 'onference

))B'2. The ( stands for Ispeed.I According to Apple, the i#hone 5:( is up to

twice as fast as the previous i#hone 5: model. That applies both to accessing the

data networ! and launching applications. *n real-world tests, 4ournalists found that

the i#hone 5:( often was more eective at pic!ing up 5: signals from the cell

phone carrier than its predecessor.

ut the i#hone 5:( isn"t 4ust faster than previous models. *t also boasts some new

features. Dere"s a rundown of what you"ll nd on the i#hone 5:(%

7ore storage space% There are two versions of the i#hone 5:(% 1? : and 5+

: models. This doubles the capacity of older i#hone models. oth models

are available in white or blac!.

Kideo camera% Cot only does the i#hone 5:("s camera capture larger photos

5.+ megapiels versus the i#hone 5:"s +.-megapiel camera2, it can record

video at 5 frames per second, too. The camera can focus automatically or

you can use the touch screen to tell the camera where to focus the image. *t

also ad4usts the image"s white balance automatically.
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Koice control% )hile many other phones on the mar!et have voice dialing

features, the i#hone 5:("s voice control etends the functionality to other

parts of the phone. Cot only can you ma!e calls by spea!ing into your phone,

you can also control music playbac! and other functions.

'ompass% )hen paired with the accelerometer and :#( receiver, the i#hone5:("s compass helps !eep i#hone owners from getting lost. *t also allows app

developers the opportunity to develop augmented reality applications.

Oleophobic screen% One problem with touch screens is that they tend to

attract smudges. The i#hone 5:( has an oleophobic screen. An oleophobic

material repels oils, !eeping the screen relatively smudge-free.

Tethering% *f your cell phone carrier allows it, you can use the i#hone 5:( as a

modem for your computer. (imply hoo! the i#hone 5:( to the computer

using an Apple H( cord and you can surf the )eb at 5: speeds. (ome

carriers don"t allow tethering, including ATLT in the Hnited (tates.

)hile these features were touted as impressive new technology, many of them

already eisted on other smartphones.

iPho!e 1

)hen (teve 6obs unveiled the i#hone < in +1, he conrmed a lot of rumors that

had been swirling around for more than a month. The technology news blog

:i$modo made headlines of its own when it ran a story about a prototype version of

the i#hone < ahead of the oGcial announcement. The phone belonged to

an Appleemployee who apparently left it behind at a bar by accident. :i$modo

revealed many of the phone"s features, though Apple had remotely loc!ed most of

its functionality.

6obs slyly ac!nowledged the fact that his audience !new more about the phone than

they should, but he still had some surprises up his sleeve. The new i#hone"s design

was a departure from previous models. *nstead of the slightly curved bac!, the

i#hone < has 3at surfaces. *t also has two cameras. The rear-facing camera ta!es 0-

megapiel pictures and can capture /+p video. *t also has an E8B 3ash for low-light

photography Msource% AppleN. The front-facing camera plays a part in Apple"s

@acetime app, which lets you ma!e video calls to other i#hone


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7ultitas!ing

DB video recording and editing

camera autofocus

three-ais gyroscope

dual-mic noise suppression

A year after the release of the i#hone


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1uality sound and t more

comfortably into a wider variety of ear shapes than their predecessors 8aruds.

About 0 million units of the i#hone 0 were sold during the rst wee!end of

availability, brea!ing the sales records of the i#hone


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*n terms of media hype, most focus went directly to the i#hone 0s, which features

signicant hardware changes.

Apple overhauled the iconic home button by adding an integrated ngerprint

sensor. After registering a ngerprint with the device, a simple ngertip press

unloc!s the phone, authori$es online purchases and completes other actions thatre>uire heightened security.

This capability is called Touch*B. The sensor can read sub-surface s!in layers at a

resolution of 0 piels per inch and at any angle. 9ou can register more than one

person on the phone so that multiple people can access secure functions. Although

hailed as a step forward in user-friendly security, the feature was defeated by a

computer club 4ust a few days following the phone"s release Msource% Bia$N.

*nstead of the A? chip, the 0s sports a new A/ processor, which is the rst ?uality. The camera also

has a wider aperture at fF+.+2, slow motion video, 1 frames per second burst mode

and image stabili$ation.

Dardware aside, both the 0c and 0s run iO( /, which is Apple"s newest mobile

operating system. On the net page you"ll read all about iO("s new features.

iOS 3

A few advance reviewers bashed the latest i#hones as rather stale in terms of

hardware. Dowever, iO( / includes whole lot of ma4or changes for Apple devotees to

process.

@irst and foremost, the overall visual interface is >uite dierent from older versionsof iO(. *t"s considered the biggest overhaul for the operating system since +/. *n

iO( /, gone are the frilly graphical 3ourishes, such as fau leather for the calendar

app and wood for the Cewsstand app, replaced by a simpler, stripped-down

appearance. There are new icons and fonts, transparency eects, and advanced

graphics physics designed to ma!e the display loo! more three dimensional.
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The so-called live wallpapers are on prominent display in this iO(. These wallpapers

feature on-screen bubbles that 3oat about in dierent directions depending the

phone"s orientation.

eyond the eye candy, there are plenty of changes in the way iO( actually wor!s,

too. One of the most notable updates is 'ontrol 'enter access. 6ust swipe upanywhere and you"ll have immediate access to wireless options, screen brightness,

3ashlight, airplane mode and music controls.

The burgeoning App (tore, which is at around , apps and counting, has

improved search capabilities. 9ou can lter apps by their popularity in your

geographical location, and you can lter them by age appropriateness, too, which

should please some parents. Apps can now update automatically in the bac!ground

instead of re>uiring your manual intervention.

iO( / integrates with iTunes and a range of cloud-based capabilities. *nstead of

playing only trac!s stored to the device itself, you can access music stored in

i'loud. There"s also the long-overdue ability to build #andora-li!e radio stations

around specic artists and songs.

Apple"s )eb browser, (afari, now has a combined H&E and search tet bo. That

simply means you can either directly type the )eb site you want to access or

instead initiate an *nternet search. #hones from other companies have been doing

this for some time, but this is a rst for iO(. (afari also now lets you open 4ust about

as many tabs as you want, and then swipe them away once you"re done with those

pages.

Koice-command app (iri has some new tric!s, as well. (imply say Iincrease screen

brightnessI or Iturn on )i@i,I and (iri immediately does so. 9ou can choose new

voices and languages for (iri, too.

The version of iO( is also slated for all !ind of in-vehicle integration. *n +1


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iPho!e Competitors a!" the Evolvi!g Smartpho!e *ar%et

The i#hone


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dierent radio bands, and Apple pac!s as many as possible in each version so that

it has fewer dierent models to produce and manage.

Co single carrier oers a clear-cut best option as of fall +15. (print oers an

unlimited data plan, Keri$on now only oers limited data share plans that allow

customers to share a set amount of data over multiple devices, and ATLT alsoforces new customers into similar limited data mobile share plans, but allows older

i#hone customers to be grandfathered into the unlimited plan, provided they come

into a retail store and re>uest this option, and do not order online.

'arrier voice plans for the i#hone also vary in price and available minutes. Keri$on

and ATLT are both larger networ!s that may provide better cellular coverage,

depending on your region. (print and Keri$on"s 'B7A technology cannot use voice

and data simultaneously, and the latest i#hone supports faster D(#A also !nown

as 8volved Digh-(peed #ac!et Access2data on ATLT"s :(7 networ!. *n real-world

use, data speeds vary by networ! usage and location -- Keri$on or (print could

potentially be faster than ATLT based on those factors. All carrier services are alsodeveloping much faster ET8 networ!s, but those are only available in certain areas,

and only the i#hone 0 can ta!e advantage of ET8. 9ou have to weigh a variety of

factors and pic! the best carrier, plan and phone for you.

capacitive touch screens nfees

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