Capacitive Touch Screens nfees
Transcript of 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.