From Wikipedia, the free encyclopedia Touchscreen
Touchscreen
The prototype[1] x-y mutual capacitance touchscreen (left) de-
A child solves a computerized puzzle using a touchscreen. veloped at CERN[2][3] in 1977 by Bent Stumpe, a Danish elec-
tronics engineer, for the control room of CERN’s accelerator
A touchscreen is an electronic visual display that can SPS (Super Proton Synchrotron). This was a further develop-
detect the presence and location of a touch within the ment of the self-capacitance screen (right), also developed by
display area. The term generally refers to touching the Stumpe at CERN[4] in 1972.
display of the device with a finger or hand. Touchscreens
can also sense other passive objects, such as a stylus.
Touchscreens are common in devices such as game con-
soles, all-in-one computers, tablet computers, and smart-
phones.
The touchscreen has two main attributes. First, it en-
ables one to interact directly with what is displayed,
rather than indirectly with a pointer controlled by a
mouse or touchpad. Secondly, it lets one do so without
requiring any intermediate device that would need to be
held in the hand (other than a stylus, which is optional
for most modern touchscreens). Such displays can be at-
tached to computers, or to networks as terminals. They
also play a prominent role in the design of digital appli-
ances such as the personal digital assistant (PDA), satel-
lite navigation devices, mobile phones, and video games. This touch sensitive pad on the Acer Aspire 8920 laptop can in-
crease and reduce the volume of the speakers.
History Touchscreens have subsequently become familiar in
The first touch screen was a capacitive touch screen de- everyday life. Companies use touchscreens for kiosk sys-
veloped by E.A. Johnson at the Royal Radar Establish- tems in retail and tourist settings, point of sale systems,
ment, Malvern, UK. The inventor briefly described his ATMs, and PDAs, where a stylus is sometimes used to ma-
work in a short article published in 1965[5] and then more nipulate the GUI and to enter data.
fully - along with photographs and diagrams - in an arti- From 1979–1985, the Fairlight CMI (and Fairlight CMI
cle published in 1967.[6] A description of the applicabili- IIx) was a high-end musical sampling and re-synthesis
ty of the touch technology for air traffic control was de- workstation that utilized light pen technology, with
scribed in an article published in 1968.[7] which the user could allocate and manipulate sample and
Contrary to many accounts,[8] while Dr. Sam Hurst synthesis data, as well as access different menus within
played an important role in the development of touch its OS by touching the screen with the light pen. The later
technologies, he neither invented the first touch sensor, Fairlight series IIT models used a graphics tablet in place
nor the first touch screen.[citation needed] of the light pen.
1
From Wikipedia, the free encyclopedia Touchscreen
The HP-150 from 1983 was one of the world’s earliest and not by display, chip, or motherboard manufacturers.
commercial touchscreen computers. Similar to the Display manufacturers and chip manufacturers world-
PLATO IV system, the touch technology used employed wide have acknowledged the trend toward acceptance of
infrared transmitters and receivers mounted around the touchscreens as a highly desirable user interface compo-
bezel of its 9" Sony Cathode Ray Tube (CRT), which de- nent and have begun to integrate touchscreens into the
tected the position of any non-transparent object on the fundamental design of their products.
screen.
An early attempt at a handheld game console with
touchscreen controls was Sega’s intended successor to
Technologies
the Game Gear, though the device was ultimately shelved There are a variety of touchscreen technologies:
and never released due to the expensive cost of touch-
screen technology in the early 1990s. Touchscreens Resistive
would not be popularly used for video games until the re- Main article: Resistive touchscreen
lease of the Nintendo DS in 2004.[9] A resistive touchscreen panel comprises several layers,
the most important of which are two thin, transparent
electrically-resistive layers separated by a thin space. Th-
ese layers face each other, with a thin gap between. One
resistive layer is a coating on the underside of the top
surface of the screen. Just beneath it is a similar resistive
layer on top of its substrate. One layer has conductive
connections along its sides, the other along top and bot-
tom.
When an object, such as a fingertip or stylus tip,
presses down on the outer surface, the two layers touch
to become connected at that point: The panel then be-
haves as a pair of voltage dividers, one axis at a time.
For a short time, the associated electronics (device con-
troller) applies a voltage to the opposite sides of one lay-
er, while the other layer senses the proportion (think
percentage) of voltage at the contact point. That provides
the horizontal [x] position. Then, the controller applies
a voltage to the top and bottom edges of the other layer
(the one that just sensed the amount of voltage); the first
iPad tablet computer on a stand
layer now senses height [y]. The controller rapidly alter-
nates between these two modes. As well, it sends position
Until recently, most consumer touchscreens could
data to the CPU in the device, where it’s interpreted ac-
only sense one point of contact at a time, and few have
cording to what the user is doing.
had the capability to sense how hard one is touching.
Resistive touch is used in restaurants, factories and
This is starting to change with the commercialization of
hospitals due to its high resistance to liquids and contam-
multi-touch technology.
inants. A major benefit of resistive touch technology is its
The popularity of smartphones, tablet computers,
low cost. Disadvantages include the need to press down,
portable video game consoles and many types of infor-
and a risk of damage by sharp objects. Resistive touch-
mation appliances is driving the demand and acceptance
screens also suffer from poorer contrast, due to having
of common touchscreens, for portable and functional
additional reflections from the extra layer of material
electronics. With a display of a simple smooth surface,
placed over the screen.
and direct interaction without any hardware (keyboard
or mouse) between the user and content, fewer acces- Surface acoustic wave
sories are required.
Touchscreens are popular in the hospitality field, and Main article: Surface acoustic wave
in heavy industry, as well as kiosks such as museum dis- Surface acoustic wave (SAW) technology uses ultrasonic
plays or room automation, where keyboard and mouse waves that pass over the touchscreen panel. When the
systems do not allow a suitably intuitive, rapid, or accu- panel is touched, a portion of the wave is absorbed. This
rate interaction by the user with the display’s content. change in the ultrasonic waves registers the position of
Historically, the touchscreen sensor and its accompa- the touch event and sends this information to the con-
nying controller-based firmware have been made avail- troller for processing. Surface wave touchscreen panels
able by a wide array of after-market system integrators, can be damaged by outside elements. Contaminants on
2
From Wikipedia, the free encyclopedia Touchscreen
the surface can also interfere with the functionality of
the touchscreen.[10]
Capacitive
Capacitive touchscreen of a mobile phone
Back site of Multitouch Globe create on base of Projected Ca-
pacitive Touch (PCT) technology. For more information please
Main article: Capacitive sensing
look: multitouch
A capacitive touchscreen panel consists of an insulator
such as glass, coated with a transparent conductor such
as indium tin oxide (ITO).[11][12] As the human body is flexible operation. An X-Y grid is formed either by etch-
also an electrical conductor, touching the surface of the ing a single conductive layer to form a grid pattern of
screen results in a distortion of the screen’s electrostatic electrodes, or by etching two separate, perpendicular
field, measurable as a change in capacitance. Different layers of conductive material with parallel lines or tracks
technologies may be used to determine the location of to form the grid (comparable to the pixel grid found in
the touch. The location is then sent to the controller for many LCD displays) that the conducting layers can be
processing. Unlike a resistive touchscreen, one cannot coated with further protective insulating layers, and op-
use a capacitive touchscreen through most types of elec- erate even under screen protectors, or behind weather-
trically insulating material, such as gloves; one requires and vandal-proof glass. Due to the top layer of a PCT be-
a special capacitive stylus, or a special-application glove ing glass, it is a more robust solution than resistive touch
with an embroidered patch of conductive thread passing technology. Depending on the implementation, an active
through it and contacting the user’s fingertip. This disad- or passive stylus can be used instead of or in addition to a
vantage especially affects usability in consumer electron- finger. This is common with point of sale devices that re-
ics, such as touch tablet PCs and capacitive smartphones quire signature capture. Gloved fingers may or may not
in cold weather. be sensed, depending on the implementation and gain
settings. Conductive smudges and similar interference on
Surface capacitance the panel surface can interfere with the performance.
In this basic technology, only one side of the insulator Such conductive smudges come mostly from sticky or
is coated with a conductive layer. A small voltage is ap- sweaty finger tips, especially in high humidity environ-
plied to the layer, resulting in a uniform electrostatic ments. Collected dust, which adheres to the screen due
field. When a conductor, such as a human finger, touches to the moisture from fingertips can also be a problem.
the uncoated surface, a capacitor is dynamically formed. There are two types of PCT: Self Capacitance and Mutual
The sensor’s controller can determine the location of the Capacitance. A PCT screen consists of an insulator such
touch indirectly from the change in the capacitance as as glass or foil, coated with a transparent conductor –
measured from the four corners of the panel. As it has sensing (Copper, ATO, Nanocarbon or ITO). As the human
no moving parts, it is moderately durable but has limited finger (is also a conductor) touching the surface of the
resolution, is prone to false signals from parasitic ca- screen results in a distortion of the local electrostatic
pacitive coupling, and needs calibration during manufac- field, measurable as a change in capacitance.Now PCT
ture. It is therefore most often used in simple applica- used mutual capacitance, which is the more common
tions such as industrial controls and kiosks.[13] projected capacitive approach and makes use of the fact
that most conductive objects are able to hold a charge if
Projected capacitance they are very close together. If another conductive ob-
Projected Capacitive Touch (PCT) technology is a ca- ject, in this case a finger, bridges the gap, the charge
pacitive technology which permits more accurate and field is interrupted and detected by the controller. All
3
From Wikipedia, the free encyclopedia Touchscreen
PCT touch screens are made up of an electrode - a matrix
of rows and columns. The capacitance can be changed at
every individual point on the grid (intersection). It can be
measured to accurately determine the exactly touch lo-
cation.[14] All projected capacitive touch (PCT) solutions
have three key features in common: • Sensor as matrix of
rows and columns. • Sensor lies behind the touch surface.
• Sensor does not use any moving parts.
Mutual capacitance
In mutual capacitive sensors, there is a capacitor at every
intersection of each row and each column. A 16-by-14
array, for example, would have 224 independent capaci-
tors. A voltage is applied to the rows or columns. Bring-
ing a finger or conductive stylus close to the surface of
the sensor changes the local electrostatic field which re-
duces the mutual capacitance. The capacitance change
at every individual point on the grid can be measured
to accurately determine the touch location by measuring
the voltage in the other axis. Mutual capacitance allows
multi-touch operation where multiple fingers, palms or
styli can be accurately tracked at the same time.
Self-capacitance
Self-capacitance sensors can have the same X-Y grid as
mutual capacitance sensors, but the columns and rows Infrared sensors mounted around the display watch for a
operate independently. With self-capacitance, the capac- user’s touchscreen input on this PLATO V terminal in 1981. The
itive load of a finger is measured on each column or row monochromatic plasma display’s characteristic orange glow is
electrode by a current meter. This method produces a illustrated.
stronger signal than mutual capacitance, but it is unable
to resolve accurately more than one finger, which results be pinpointed to locate the touch or even measure the
in "ghosting", or misplaced location sensing. size of the touching object (see visual hull). This technol-
ogy is growing in popularity, due to its scalability, versa-
Infrared tility, and affordability, especially for larger units.
An infrared touchscreen uses an array of X-Y infrared
LED and photodetector pairs around the edges of the Dispersive signal technology
screen to detect a disruption in the pattern of LED beams. Introduced in 2002 by 3M, this system uses sensors to de-
These LED beams cross each other in vertical and hori- tect the Piezoelectricity in the glass that occurs due to
zontal patterns. This helps the sensors pick up the exact a touch. Complex algorithms then interpret this infor-
location of the touch. A major benefit of such a system mation and provide the actual location of the touch.[15]
is that it can detect essentially any input including a The technology claims to be unaffected by dust and other
finger, gloved finger, stylus or pen. It is generally used outside elements, including scratches. Since there is no
in outdoor applications and point of sale systems which need for additional elements on screen, it also claims to
can’t rely on a conductor (such as a bare finger) to acti- provide excellent optical clarity. Also, since mechanical
vate the touchscreen. Unlike capacitive touchscreens, in- vibrations are used to detect a touch event, any object
frared touchscreens do not require any patterning on the can be used to generate these events, including fingers
glass which increases durability and optical clarity of the and stylus. A downside is that after the initial touch the
overall system. system cannot detect a motionless finger.
Optical imaging Acoustic pulse recognition
This is a relatively modern development in touchscreen In this system, introduced by Tyco International’s Elo di-
technology, in which two or more image sensors are vision in 2006, the key to the invention is that a touch
placed around the edges (mostly the corners) of the at each position on the glass generates a unique sound.
screen. Infrared back lights are placed in the camera’s Four tiny transducers attached to the edges of the touch-
field of view on the other side of the screen. A touch screen glass pick up the sound of the touch. The sound is
shows up as a shadow and each pair of cameras can then then digitized by the controller and compared to a list of
4
From Wikipedia, the free encyclopedia Touchscreen
prerecorded sounds for every position on the glass. The manufacturing and product design are no longer encum-
cursor position is instantly updated to the touch loca- bered by royalties or legalities with regard to patents and
tion. APR is designed to ignore extraneous and ambient the use of touchscreen-enabled displays is widespread.
sounds, as they do not match a stored sound profile. APR The development of multipoint touchscreens facili-
differs from other attempts to recognize the position of tated the tracking of more than one finger on the screen;
touch with transducers or microphones, as it uses a sim- thus, operations that require more than one finger are
ple table lookup method rather than requiring powerful possible. These devices also allow multiple users to inter-
and expensive signal processing hardware to attempt to act with the touchscreen simultaneously.
calculate the touch location without any references.[16] With the growing use of touchscreens, the marginal
The touchscreen itself is made of ordinary glass, giving cost of touchscreen technology is routinely absorbed into
it good durability and optical clarity. It is usually able to the products that incorporate it and is nearly eliminated.
function with scratches and dust on the screen with good Touchscreens now have proven reliability. Thus, touch-
accuracy. The technology is also well suited to displays screen displays are found today in airplanes, automo-
that are physically larger. As with the Dispersive Signal biles, gaming consoles, machine control systems, appli-
Technology system, after the initial touch, a motionless ances, and handheld display devices including the Nin-
finger cannot be detected. However, for the same reason, tendo DS and the later multi-touch enabled iPhones; the
the touch recognition is not disrupted by any resting ob- touchscreen market for mobile devices is projected to
jects. produce US$5 billion in 2009.[17]
The ability to accurately point on the screen itself is
Construction also advancing with the emerging graphics tablet/screen
hybrids.
There are several principal ways to build a touchscreen. October 2011: TapSense can distinguish between dif-
The key goals are to recognize one or more fingers touch- ferent parts of the hand, such as fingertip and fingernail,
ing a display, to interpret the command that this repre- so it can be functioned as lower case and capital letter in-
sents, and to communicate the command to the appro- struction.[18]
priate application.
In the most popular techniques, the capacitive or re-
sistive approach, there are typically four layers:
Ergonomics and usage
1. Top polyester coated with a transparent metallic
conductive coating on the bottom Fingernail as stylus
2. Adhesive spacer
3. Glass layer coated with a transparent metallic
conductive coating on the top
4. Adhesive layer on the backside of the glass for
mounting.
When a user touches the surface, the system records the
change in the electrical current that flows through the
display.
Dispersive-signal technology which 3M created in
2002, measures the piezoelectric effect — the voltage
generated when mechanical force is applied to a material
— that occurs chemically when a strengthened glass sub-
strate is touched.
There are two infrared-based approaches. In one, an
Pointed nail for easier typing. The concept of using a fingernail
array of sensors detects a finger touching or almost
trimmed to form a point, to be specifically used as a stylus on a
touching the display, thereby interrupting light beams writing tablet for communication, appeared in the 1950 science
projected over the screen. In the other, bottom-mounted fiction short story Scanners Live in Vain.
infrared cameras record screen touches.
In each case, the system determines the intended These ergonomic issues of direct touch can be bypassed
command based on the controls showing on the screen at by using a different technique, provided that the user’s
the time and the location of the touch. fingernails are either short or sufficiently long. Rather
than pressing with the soft skin of an outstretched fin-
Development gertip, the finger is curled over, so that the tip of a fin-
gernail can be used instead. This method does not work
Most touchscreen patents were filed during the 1970s
on capacitive touchscreens.
and 1980s and have expired. Touchscreen component
5
From Wikipedia, the free encyclopedia Touchscreen
The fingernail’s hard, curved surface contacts the to neck and shoulder pains due to their posture and the
touchscreen at one very small point. Therefore, much repetitiveness of their movements while painting.[21]
less finger pressure is needed, much greater precision is
possible (approaching that of a stylus, with a little experi-
ence), much less skin oil is smeared onto the screen, and
Screen protectors
the fingernail can be silently moved across the screen Some touchscreens, primarily those employed in smart-
with very little resistance,[citation needed] allowing for se- phones, use transparent plastic protectors to prevent
lecting text, moving windows, or drawing lines. any scratches that might be caused by day-to-day use
The human fingernail consists of keratin which has from becoming permanent.
a hardness and smoothness similar to the tip of a stylus
(and so will not typically scratch a touchscreen). Alter-
natively, very short stylus tips are available, which slip
See also
right onto the end of a finger; this increases visibility of • Dual-touchscreen
the contact point with the screen. • Energy harvesting
• Flexible keyboard
Fingerprints • Gestural interface
• Graphics tablet
Touchscreens can suffer from the problem of finger-
• Graphics tablet-screen hybrid
prints on the display. This can be mitigated by the use
• List of Touch Solution manufacturers
of materials with optical coatings designed to reduce the
• Tablet PC
visible effects of fingerprint oils, or oleophobic coatings
• Touch switch
as used in the iPhone 3G S, which lessen the actual
• Touchscreen remote control
amount of oil residue, or by installing a matte-finish anti-
• Omnitouch
glare screen protector, which creates a slightly rough-
• SixthSense
ened surface that does not easily retain smudges, or by
reducing skin contact by using a fingernail or stylus.
Notes
Combined with haptics [1] The first capacitative touch screens at CERN, CERN
Touchscreens are often used with haptic response sys- Courrier, 31 March 2010, http://cerncourier.com/
tems. An example of this technology would be a system cws/article/cern/42092, retrieved 2010-05-25
that caused the device to vibrate when a button on the [2] Bent STUMPE (16 March 1977), A new principle for x-
touchscreen was tapped. The user experience with y touch system, CERN, http://cdsweb.cern.ch/
touchscreens lacking tactile feedback or haptics can be record/1266588/files/StumpeMar77.pdf, retrieved
difficult due to latency or other factors. Research from 2010-05-25
the University of Glasgow Scotland [Brewster, Chohan, [3] Bent STUMPE (6 February 1978), Experiments to find
and Brown 2007 and more recently Hogan] demonstrates a manufacturing process for an x-y touch screen, CERN,
that sample users reduce input errors (20%), increase in- http://cdsweb.cern.ch/record/1266589/files/
put speed (20%), and lower their cognitive load (40%) StumpeFeb78.pdf, retrieved 2010-05-25
when touchscreens are combined with haptics or tactile [4] Frank BECK & Bent STUMPE (24 May 1973), Two
feedback [vs. non-haptic touchscreens]. devices for operator interaction in the central control of
the new CERN accelerator, CERN,
Gorilla arm http://cdsweb.cern.ch/record/186242/files/
The Jargon File dictionary of hacker slang defined "gorilla p1.pdf, retrieved 2010-05-25
arm" as the failure to understand the ergonomics of ver- [5] Johnson, E.A. (1965). "Touch Display - A novel
tically mounted touchscreens for prolonged use. The input/output device for computers". Electronics
proposition is that the human arm held in an unsup- Letters 1 (8): 219–220.
ported horizontal position rapidly becomes fatigued and [6] Johnson, E.A. (1967). "Touch Displays: A
painful, the so-called "gorilla arm".[19] It is often cited as Programmed Man-Machine Interface". Ergonomics
a prima facie example of what not to do in ergonomics. 10 (2): 271–277.
Vertical touchscreens still dominate in applications such [7] Orr, N.W.; Hopkins, V.D. (1968). "The Role of Touch
as ATMs and data kiosks in which the usage is too brief to Display in Air Traffic Control.". The Controller 7:
be an ergonomic problem.[citation needed] 7–9.
Discomfort might be caused by previous poor posture [8] Mary Bellisn, ABOUT.com,
and atrophied muscular systems caused by limited phys- http://inventors.about.com/library/inventors/
ical exercise.[20] Fine art painters are also often subject bltouch.htm, retrieved 2010-08-27
6
From Wikipedia, the free encyclopedia Touchscreen
[9] Travis Fahs (April 21, 2009). "IGN Presents the compression, Langford ML, Occup Health Saf. 1994
History of SEGA". IGN. p. 7. http://retro.ign.com/ Sep;63(9):38-40, 42". Ncbi.nlm.nih.gov.
articles/974/974695p7.html. Retrieved 2011-04-27. http://www.ncbi.nlm.nih.gov/pubmed/9156441.
[10] Patschon, Mark (1988-03-15). Acoustic touch Retrieved 2012-01-04.
technology adds a new input dimension. Computer [21] "Shoulder pain made me suffer for my art By
Design. pp. 89–93. http://rwservices.no-ip.info:81/ ADRIAN LEE Publication: The Express Date:
pens/biblio88.html#Platshon88 Tuesday, January 5, 2010". Allbusiness.com.
[11] Kable, Robert G. (1986-07-15). Electrographic 2010-01-05. http://www.allbusiness.com/sports-
Apparatus. United States Patent 4,600,807. recreation/sports-games-outdoor-recreation-
http://rwservices.no-ip.info:81/pens/ rugby/13682705-1.html. Retrieved 2012-01-04.
biblio86.html#Kable86
[12] Kable, Robert G. (1986-07-15). Electrographic
Apparatus. United States Patent 4,600,807 (full
References
image). http://www.freepatentsonline.com/ • Shneiderman, B. (1991). "Touch screens now offer
4600807.pdf compelling uses". IEEE Software 8 (2): 93–94, 107.
[13] "Please Touch! Explore The Evolving World Of doi:10.1109/52.73754.
Touchscreen Technology". electronicdesign.com. • Potter, R.; Weldon, L. & Shneiderman, B. (1988).
http://electronicdesign.com/Articles/ Improving the accuracy of touch screen: An experimental
Index.cfm?AD=1&ArticleID=18592. Retrieved evaluation of three strategies. Proc. CHI’88. Washington,
2009-09-02. DC: ACM Press. pp. 27–32.
[14] Knowledge base: Multi-touch hardware • Sears, A.; Plaisant, C. & Shneiderman, B. (1992). "A
[15] Beyers, Tim (2008-02-13). "Innovation Series: new era for high precision touchscreens". In
Touchscreen Technology". The Motley Fool. Hartson, R. & Hix, D.. Advances in Human-Computer
http://www.fool.com/investing/general/2008/02/ Interaction. 3. Ablex, NJ. pp. 1–33.
13/innovation-series-touchscreen- • Sears, A. & Shneiderman, B. (1991). "High precision
technology.aspx. Retrieved 2009-03-16. touchscreen: Design strategies and comparison with
[16] Acoustic Pulse Recognition Touchscreens. Elo Touch a mouse". Int. J. of Man-Machine Studies 34 (4):
Systems. 2006. pp. 3. http://media.elotouch.com/ 593–613. doi:10.1016/0020-7373(91)90037-8.
pdfs/marcom/apr_wp.pdf. Retrieved 2011-09-27 • Holzinger, A. (2003). "Finger Instead of Mouse: Touch
[17] "Touch Screens in Mobile Devices to Deliver $5 Screens as a means of enhancing Universal Access".
Billion Next Year | Press Release". ABI Research. In: Carbonell, N.; Stephanidis C. (Eds): Universal Access,
2008-09-10. http://www.abiresearch.com/press/ Theoretical Perspectives, Practice, and Experience. Lecture
2615:
1231-Touch+Screens+in+Mobile+Devices+to+Deliver+$5+Billion+Next+Year. Science 2615 387–397.
Notes in Computer
Retrieved 2009-06-22.
[18] "New Screen Technology, Tap Sense, Can
Distinguish Between Different Parts Of Your Hand".
External links
http://techcrunch.com/2011/10/19/new-screen- • Howstuffworks - How do touchscreen monitors
technology-tapsense-can-distinguish-between- know where you’re touching?
different-parts-of-your-hand/ • MERL - Mitsubishi Electric Research Lab (MERL)’s
research on interaction with touch tables.
?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Techcrunch+%28TechCrunch%29.
Retrieved October 19, 2011. • Jefferson Y. Han et al. Multi-Touch Interaction
[19] "gorilla arm". Catb.org. http://catb.org/jargon/ Research. Multi-Input Touchscreen using Frustrated
html/G/gorilla-arm.html. Retrieved 2012-01-04. Total Internal Reflection.
[20] USA (2011-10-03). "Poor posture subjects a • Dot-to-Dot Programming : Building Microcontrollers
worker’s body to muscle imbalance, nerve • Knowledge base: Multi-touch hardware
Retrieved from "http://en.wikipedia.org/w/index.php?title=Touchscreen&oldid=475095162"
Categories:
• Touchscreens
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