Importance

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Abstract

A light pen of the type having a photoreceptor for sensing the signal from a CRT computer display and outputting to computer logic the location of the photosensing light pen is disclosed. The improvement herein is the incorporation of an accelerometer on the light pen actuated by tapping the pen gently on the screen. The accelerometer has the preferred form of a microphone acoustically deadened as by the placement of silicone rubber over the acoustical channel. The rubber acts as an accelerometer mass outputting a high frequency signal upon tapping of the light pen on the glass covering a CRT screen. A monostable amplifier opens a signal gate to conventional computer measuring logic for that duration necessary to assure one complete raster sweep of the screen. A light receptor at the screen end of the light pen outputs through a video amplifier and fast comparator to measure the precise moment of video raster passage. This light measurement is transmitted to conventional gate logic interior of the computer and compared to raster location, and converted into pen location.

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First Claim