How it works

The grid is made by a number of IR Light Emitting Diodes (LEDs) along the bottom and right display borders, and corresponding IR photo transistors at the opposite borders.The IR beams pass through an IR transparent bezel that protects the touch system against the environment and ambient visible light.

When a finger or stylus enters the grid, one or more beams are obstructed. The IR controller detects the absence of light, calculates the X,Y pointer position and transmits it through the PS/2 mouse interface.By measuring partially blocked rays at the edges of the obstruction, the controller can interpolate the X,Y pointer position with a better resolution than the distance between the beams.If a beam becomes permanently blocked by dirt, it is ignored.

The Micronix InfoTouch uses the standard PS/2 mouse protocol, so no special driver is necessary in the PC - it only requires the acceleration setting in the mouse driver to be turned off.And since the beams are located at fixed positions relative to the display, no calibration of X and Y positions are needed.