SENSOR SIGNAL READER

PURPOSE:To eliminate the influence of a temperature change by providing a read timing signal generating circuit which supplies a clamp pulse, which clamps the output of a sensor at a reference voltage in the output signal period of non-irradiation of light, to a clamping circuit. CONSTITUTION:A CCD sensor 1 is driven by a driving pulse phiM supplied from a read timing signal generating circuit 5 and generates a signal, and an output signal V0 is outputted in an effective picture element part where a photosensor 2 as a photodetector is irradiated with light, but a dark output VT due to the sensor temperature is outputted in an ineffective picture element part where it is not irradiated with light. The output signal of the CCD sensor 1 is amplified by an amplifier 3 and is clamped by a clamp pulse phiNC supplied from the read timing signal generating circuit 5 in a clamp generating circuit 4. That is, the voltage of the output signal period when the sensor 1 does not sense is clamped as the reference voltage. Thus, a dark output component VT dependent upon the temperature change is eliminated to obtain the signal which is not affected by the temperature change and proportional to only the extent of sensing like the quantity of irradiated light.