Patent ID: 9063014
Filing Date: 2015-06-23
Classification: G01J

Abstract:
1. A photodetector control circuit, which is provided in a photodetector for detecting light from a photodiode using a phototransistor, and which controls drive of the photodiode and detection of a current of the phototransistor, the photodetector control circuit comprising: a received light amount detecting unit that detects a detection current, which flows through the phototransistor in accordance with a received light amount, by converting the detection current into a detection voltage, and compares the detection voltage with a reference voltage detected during reception of a reference light amount, to thereby detect a change in the received light amount; a diode current control unit for controlling a diode current that is caused to flow through the photodiode; a control unit that detects a temperature based on a forward drop voltage of the photodiode, estimates a current change rate of the phototransistor based on the detected temperature, multiplies the estimated change rate by a preset coefficient to thereby convert the phototransistor current change rate into a diode current change rate, and controls the diode current control unit to modify the diode current in accordance with the obtained diode current change rate.