Optical information detection circuit and detecting photoelectrically converted signal from light receiving means comprising at least two light receiving elements

摘要

An optical information detection circuit having first and second photodiodes (referred to as "PD") and two resistances so that a power voltage Vcc is divided by the two resistances. A potential difference between the power voltage Vcc and the connection point between the two resistances is applied as a reverse bias to the first PD, and the potential at the connection point is applied as a reverse bias to the second PD. The photomagnetic signals respectively input to the first and second PD systems of a differential optical detection system have an opposite phase relation therebetween. The first PD and second PD obtain signals from a cathode and an anode, respectively. The currents from the first PD and second PD thus have an in-phase relation, are converted into voltages by the two resistances and summed, as well as being output as a photomagnetic signal from an output terminal at the connection point.