Detecting circuit of interruption of optical input

Abstract

Abstract PURPOSE:To detect the interruption of an optical input, by discriminating the state that an amplitude of a bias voltage to a photo diode is a predetermined value or over and the photo current is the predetermined value or over. CONSTITUTION:The photo current flowing to the photo diode 1 is extracted by inserting a minute resistor (RP)10, and inputted to an amplifier 4 via an amplifier 3 as a voltage V2 to a photo current IAPD. Further, it is compared with a threshold voltage Ip2. On the other hand, the bias voltage VAPD to the photo diode 1 is extracted as an input voltage V1 of the amplifier 2 and compared with a threshold voltage VR1. When the output of the amplifiers 2, 4 is both a high level, a detecting terminal goes to a high level and the interruption of optical input is detected.

Inventors

• 👤 Nobuhide Yamaguchi
• 👤 山口　伸英

Bibliographic Details