| 摘要 |
PURPOSE:To make the constitution of an initial state circuit simple and to improve S/N by disposing a photodetector which receives the radiations reflected from an object and further an other photodetector for cancelling noise, and connecting these to a circuit in such a way that the electric outputs thereof are in opposition to each other. CONSTITUTION:A photodetector for detection of the signal light receiving the radiations reflected from an object and an other photodetector for cancelling noise of roughly sauce characteristics and photodetecting area are disposed in parallel and are connected to a circuit in such a way that the electrical outputs of these photodetectors are in opposition to each other. The signal light from a projecting element 3 reflected by, for example, an object 1, is condensed with a photodetecting lens 4, and the spot image thereof moves on a photodetector 5. Since this signal light is not made incident to a photodetector 11 which is separated by means of an insulating region 12 on the same chip as that for said element and is so formed that the electric outputs are in opposition to each other, consideration for shielding, etc. can be omitted, and the signal processing of high S/N is reduced in costs, whereby the circuit suited for circuit integration is constituted. |
