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Abstract

The touch-sensor technology is about using our fingers or some other pointer, to view and manipulate information on a screen. On a conventional system, with every mouse click, the operating system registers a mouse event. With a touch-screen system, every time your finger touches the screen, a touch event is registered.

Description of A Basic Touch-Sensor Screen System


A basic touch-screen system is made up of three components:


1. A touch sensor
2. Controller
3. Software driver

The touch-sensor is a clear panel, which when touched, registers a voltage change that is sent to the controller. The controller processes this signal and passes the touch event data to the PC through a bus interface. The software driver takes this data and translates the touch events into mouse events.

A touch-screen sensor any of the following five mechanics: resistance, capacitance, acoustics, optics and mechanical force.

1. Resistance-based sensors.

A resistant sensor uses a thin, flexible membrane separated from a glass or plastic substance by insulating spacers. Both layers are coated with ITO (Indium-tin-oxide). These metallic coatings meet when a finger or stylus presses against the screen, thus closing an electric circuit.

2. Capacitance-based sensors.

Here voltage is applied to the corners of the screen with electrodes spread uniformly across the field. When a finger touches the screen, it draws current from each current proportionately. The frequency changes are measured to determine the X and Y coordinates of the touch event.