Touchscreens

Input/output devices have an important role in computers. Different input/output devices used nowadays are timers, analog to digital converters, digital to analog converters, keyboards, light emitting diodes, cathode ray tubes, liquid crystal displays, plasma panel displays, field emission displays, touchscreens etc. Here touchscreen is a latest and advanced technology. A touchscreen is an input device overlaid on an output device. When a user touches the surface of the screen, it registers the position of the touch and delivers information and allows user to respond to the information by another touch. There exist two varieties of touchscreens- resistive and capacitive. A resister touchscreen employs a two-dimensional voltmeter to sense position. It consists of two conductive sheets separated by spacer balls. The sheet at the top is made flexible to touch the bottom sheet. A voltage is applied across the sheet which causes a voltage gradient to appear across it. An analog to digital converter is used to measure and analyze this voltage gradient.