Touch Screen

Published:2010/11/25 2:00:00 Author:Michelle From:SeekIC

We use touch screens everywhere: tourist kiosks, automatic teller machines, point-of-sale terminals, industrial controls. Half a dozen vendors, plus in-house departments at major manufacturers, produced $800 million worth in 2000. The market is growing because the interfaces are easy-to-use, durable and inexpensive.
　　
Touch screens employ one of three physics principles for detecting the point of touch. Pressing a “resistive” design with a finger or other stylus raises a voltage. In “capacitive” models, a finger draws a minute current (this method is often used for cursor pads on notebook computers). In other designs, a finger or stylus interrupts a standing pattern of acoustic waves or infrared lights that blanket the surface.

Most people are unaware of the type of screen they are using. Push the screen lightly with your fingernail (not your skin). If it responds, it could be resistive or infrared. In this case, place two separated fingers against the screen at the same time. If the cursor moves beneath one finger, the unit is infrared ; if the cursor moves between the fingers, it is resistive. If the unit does not respond to your fingernail, again place two separated fingers against it. If the cursor moves beneath one finger, the unit is acoustic wave; if the cursor moves between the fingers, it is capacitive. Related chip is:MRF453 .

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