What is touch screen?

• A touch screen is an electronic visual display that can detect the presence and location of a touch within the display area.

• The term generally refers to touching the display ofthe device with a finger or hand. Touchscreens can alsosense other passive objects, such as a stylus.

The touch screen has two main attributes.

First, it enables 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 touch screens).

HISTORY OF TOUCHSCREEN

The first touch screen was a capacitive touch screen developed

by E.A. Johnson at the Royal Radar Establishment, Malvern, UK.

The inventor briefly described his work in a short article published in 1965 and then more fully - along with photographs

and diagrams - in an article published in 1967.

A description of the applicability of the touch technology for air traffic control was described in an article published in 1968.

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• The HP-150 from 1983 was one of the world's earliest

commercial touch screen computers.

•The touch technology used employed infrared transmitters and receivers mounted around the bezel of its 9" Sony Cathode Ray

Tube (CRT), which detected the position of any non-transparent object on the screen.

•Then came the SEGAS gaming console with

touch screen controls in early 1990’s.

How Does a Touch screen Work?

A basic touch screen has three main components ; 1. Touch sensor;2. Controller; 3. Software driver.

The touch screen is an input device, so it needs to be combined with a display and a PC or other device to make a complete touch input system.

Resistive

Surface acoustic

wave

Capacitive

Infrared

Optical Imaging

Technologies

Structure

Resistive touch

screens consist of a glass or acrylic panel that is coated with electrically conductive and resistive layers made with indium tin oxide (ITO) .The thin layers are separated by invisible spacers.

Resistive touch screen

Characters:

1. Cost effective solutions

2. Activated by a stylus, a finger or gloved hand

3. Not affected by dirt, dust, water, or light

4. 75%~85% clarify

5. resistive layers can be damaged by a very sharp object

Surface acoustic wave

Surface wave technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing.

Capacitive touch screen

A capacitive touch screen panel is coated with a material that stores

electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing.

Infrared

An 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.

Optical Imaging

In this two or more image sensors are placed around the edges of the screen. A touch shows up as a shadow and each pair of cameras can then be pinpointed to locate the touch.

Comparison

Applications

•Museums

•Library resource guides

•Corporate information

•Airport terminal passenger internet

and emails

•ATM’s

•Restaurants'

•Grocery stores

PROS User 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

CONS

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 applies an additional not 100% transparent

Fatigue