Patent ID: 7075051

Claim:
A semiconductor photosensor device which outputs a detection result when a trigger signal is inputted, comprising: a photodiode current arithmetic circuit which is in an operating state regardless of whether before or after the input of the trigger signal, and which outputs a photocurrent generated by light irradiation; a first amplifier which is in an operating state regardless of whether before or after the input of the trigger signal, and which amplifies and outputs the output of the photodiode current arithmetic circuit; and a second amplifier which is in a non-operating state before the input of the trigger signal, wherein the second amplifier shifts to an operating state upon receiving the trigger signal, and amplifies and outputs the output of the first amplifier, wherein a power supply voltage is not supplied to the second amplifier before receiving the trigger signal, but the power supply voltage is supplied to the second amplifier upon receiving the trigger signal.