Touch screens

Most of us are now familiar with touch screens where you have to press your finger on the relative part of the screen to input data.

The monitor detects the position of a finger placed on the screen. One method of doing this is to have a series of horizontal and vertical infrared beams directed across the screen. Position is calculated from detecting which beams have been interrupted. A more commonly used method is the one explained in the diagram above.

This method of input has limited accuracy because the input device is fairly large. It can be used to choose menu items from a selection displayed. Its principal use is in data display applications where the user can select one of a limited number of choices by pointing at the screen. It has the advantage of limiting what the user can do to the system. Many banks and building societies use these devices for customer services

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