Photodetecting circuit with compensated integration signal

摘要

The optical input detection apparatus is adapted to integrate the value of the light received corresponding to the sum of the value of the light received by the light receiving device during driving of the light emitting device and the external flood light, deduct from the integration value the value of the light received equivalent to the external flood light received by the photodetector during the non-driving period following the driving of the light emitting device, compensate the integration value to the signal corresponding to the light emitting output and output the compensated signal to the comparator for comparison. Consequently, the presence or absence of an interruption in the light beam may be detected without being affected by the external flood light.