Photosensor circuit

摘要

A photosensor circuit (1) includes an initial setting unit (2) which is able to preclude the occurrence of a residual image. When an optical signal is detected by a photoelectric transducer (PD), the initial setting unit (2) sets the gate voltage of an n-channel MOS transistor (Q1) at a high value for a predetermined time to lower the drain-source impedance of the n-channel MOS transistor (Q1) to thereby control charge or discharge of a capacitor (C) connected to a source terminal (P). A p-channel MOS transistor circuit is also described. <IMAGE>