Touchscreen
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Transcript of Touchscreen
TOUCHSCREENBy – Fazle Qadir Chimthanawala
TOUCHSCREEN
A touchscreen is an electronic visual display that the user can control through simple or multi-touch gestures by touching the screen with a special stylus/pen or one or more fingers.
The touchscreen enables the user to interact directly with what is displayed, rather than using a mouse, touchpad, or any other device other than a stylus.
Touchscreens are common in devices such as game consoles, all-in-one computers, tablet computers, and smartphones. They can also be attached to computers or, as terminals, to networks.
HISTORY
Touch screens emerged from academic and corporate research labs
This sensor was known as “Elograph”.
Touch screens first gained some visibility with the invention of the computer-assisted learning terminal, which came out in 1975 as part of the PLATO project(Programmed Logic for Automatic Teaching Operations)[.
In 1971, the first "Touch Sensor" was developed by Doctor Sam Hurst (founder of Elographics) while he was an instructor at the University of Kentucky.
COMPONENTS
Touch sensor
Controller
Software driver
TYPESResistive
Surface acoustic wave
Capacitive
Infrared grid
Infrared acrylic projection
Acoustic pulse recognition
Dispersive signal technology
Optical imaging
RESISTIVE
Composed of several layers
Two Electrically conductive layers
SURFACE ACOUSTIC WAVESIt uses ultrasonic waves.
When the panel is touched, a portion of the wave is absorbed.
CAPACITIVE
Consist of an insulator such as glass
Coated with transparent conductor such as ITO (Indium Tin Oxide)
Touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance.
INFRARED GRIDAn infrared touch screen uses an array of X-Y infrared LED and photo detector pairs around the edges of the screen to detect a disruption in the pattern of LED beams.
ADVANTAGESUser friendly
Fast response
Error free input
Use finger , fingernail , gloved hands , stylus or any soft tip pointer
Easy to clean
Does not interfere mouse and keyboard
Make computing easy , powerful and fun
It benefits children
DISADVANTAGES
Finger stress
Fingerprints
Screen has to be really big not to miss things when pressing them with your finger
Big screen leads to low battery life
Touch screen means screen can’t be read too well in direct sunlight as it is not 100% transparent.
WORKING OF A IPHONE TOUCHSCREEN
Driving lines carry current.
Sensing lines detect the current at nodes.