Patent ID: 8772697

Claim:
A photodetector device for measuring illuminance of visible light, comprising: a first light receiving element comprising infrared light blocking means for blocking infrared light; a second light receiving element comprising light blocking means for blocking incident light; storage means for storing an electric charge generated in the first light receiving element; storage means for storing an electric charge generated in the second light receiving element; a difference circuit for outputting a difference between the electric charge stored in the first light receiving element and the electric charge stored in the second light receiving element; a comparator for detecting that a voltage based on the difference has reached a predetermined voltage and outputting a detection signal; a control circuit for resetting, based on the detection signal, the electric charge stored in the first light receiving element, the electric charge stored in the second light receiving element, and the difference obtained by the difference circuit to initial values, and then causing the storage means for the first light receiving element and the storage means for the second light receiving element to store electric charges again; and a storage detection circuit for outputting the detection signal to the control circuit when an output voltage of one of the first light receiving element and the second light receiving element reaches a predetermined potential.