An improved sequentially scanned crossed light beam position encoder including means for detecting and transmitting the address of interrupted light beams, means for electrically detecting the subsequent status of an initially detected interrupted beam and means for inhibiting subsequent transfer of the address of the initially detected interrupted beam in the event the subsequent beam status at the address has not changed. The improvement includes means for continuously sequentially activating pairs of non-visible radiation sources and detectors to continuously scan the surface of a display device with respective crossing beams, and means responsive to the initial detection of an interrupted beam at an associated address and responsive to the subsequent absence of beam interruption at the same address on a subsequent scan to reset the system and prepare it for further detection of new beam interruptions.
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