Ambient light rejecting quad photodiode sensor
First Claim
1. A photodiode array for detecting a projected image in the presence of ambient light, comprising a plurality of image sensing photodiodes connected together in parallel with like polarity, and a plurality of further photodiodes connected in parallel with and with reverse polarity to respective ones of said image sensing photodiodes, for compensating the effects of said ambient light on and sensor dark current within said image sensing diodes.
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Abstract
An ambient light rejecting quad photodiode sensor having compensation diodes connected with reverse polarity to respective quadrant photodiodes within the sensor, the compensation diodes being located outside of the area of illumination. By direct connection of compensation diodes in reverse polarity to each quadrant of the quad photodiodes, a large boost in signal to noise ratio is achieved for eliminating the effects of ambient room light as well as sensor dark current.
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Citations
7 Claims
- 1. A photodiode array for detecting a projected image in the presence of ambient light, comprising a plurality of image sensing photodiodes connected together in parallel with like polarity, and a plurality of further photodiodes connected in parallel with and with reverse polarity to respective ones of said image sensing photodiodes, for compensating the effects of said ambient light on and sensor dark current within said image sensing diodes.
Specification