Technique Behind Touch Screen

Today we are using many technologies.As we go through with emerging technologies there is also the necessity to know, that how they actully work. This time i am going to discuss a very well known Technology that is TOUCH SCREEN.  As we know that concept of all present or future coming technologies has been already defined in past, same occured here.The touch generation started at early as 1971, when the first touch sensor was developed by Doctor Sam Hurst. Before going through the technique this must be know that what is the basic building block of Touch screen. Touchscreen basically comprises of a touchable surface and an electronic device on which the operation or touch gestures are to be performed. The device, on which we touch, is made of glass beneath it there are many operating layer,  which continuously scans for any touching activity happening over its surface. The touchscreen also have some sensors for specific detection methods, sometimes it detects hand or fingers only, sometimes pen or other object like stylus. The basic requirement of an device is , a conductive coating polyester layer, Adhesive spacer, Glass layer coated with transparent conductive metallic layer, Adhesive layer on the backside of the glass for mounting. Now There are three basic systems that are used to recognize a person's touch:

• Resistive
• Capacitive
• Surface acoustic wave

Resistive Touch Screen Technology: The Analog Resistive touch screen is a sensor consisting of two opposing layers, each coated with a transparent resistive material called indium tin oxide (ITO). The ITO used has a typical sheet resistivity between 100 and 500 ohms per square. The layers are separated by a pattern of very small transparent insulating dots. Silver ink bus bars (~50mW/sq) make an electrical connection to the surface of the ITO at the outside edges, spanning the desired axis of the given layer. Silver ink traces (~50mW/sq) connect the bus bars to an electromechanical connector used for interfacing to the sensor. The cover sheet has a hard, durable coating on the outer side, and a conductive coating on the inner side. When a user touches the screen, the two layers make contact in that exact spot. The change in the electrical field is noted and the coordinates of the point of contact are calculated by the computer. Once the coordinates are known, a special driver translates the touch into something that the operating system can understand, much as a computer mouse driver translates a mouse's movements into a click or a drag.