Instantaneous photodetecting circuit

Abstract

Abstract PURPOSE: To make possible the detection of instantaneous light without being affected by the intensity of steady light by providing an electric current control circuit allowing the passage of only the photocurrent of the steady light and an electric current circuit receiving pulse-form photocurrent. CONSTITUTION: An electric current control circuit is formed by a transistor TR31, a buffer circuit 33 for negative feedback and a capacitor 34 for delaying and allows the passage of only the steady light from a photoelectric element 30. Now, when the pulse-form photocurrent superposed on the steady light from the element 30 inputs, the TR31 allows the passage of the steady light but blocks the passage of the pulse- form photocurrent. Hence, the pulse-form photocurrent is supplied to the base of the TR35 in which constant current is flowed by a constant current source 36. As a result, the impulse-form photocurrent is taken out as the collector current amplified by the TR35 irrespective of the intensity of the steady light. In this way, the instantaneous light may be taken out. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Motonobu Matsuda

Bibliographic Details