초록 ▼

A dynamic level shifter for photoelectric touch panels incorporating a plurality of photoelectric transducers periodically senses the ambient light level, immediately before the interval when each transducer can receive a pulse of radiant energy during normal operation of the panel. The output of th

A dynamic level shifter for photoelectric touch panels incorporating a plurality of photoelectric transducers periodically senses the ambient light level, immediately before the interval when each transducer can receive a pulse of radiant energy during normal operation of the panel. The output of the phototransducer during the such interval is compared with the output during the previous ambient interval, to develop a signal indicative of the presence or absence of the pulse, irrespective of ambient light fluctuations.

대표청구항 ▼

In a touch input device having a panel and means for defining a plurality of beams of radiant energy arranged parallel to the panel, each of said beams being defined by an energy emitter and an energy detector, the improvement comprising sampling means for sampling the ambient output level of one of

In a touch input device having a panel and means for defining a plurality of beams of radiant energy arranged parallel to the panel, each of said beams being defined by an energy emitter and an energy detector, the improvement comprising sampling means for sampling the ambient output level of one of said detectors immediately prior to the energization of its associated emitter, storage means for temporarily storing a signal representative of said ambient output level, and comparator means for comparing the instantaneous output of said detector with said stored signal during a subsequent interval while said emitter is energized for deriving a signal manifesting the interruption or noninterruption of said beam.