Distance measuring device

Abstract

Abstract PURPOSE:To decide on infinite-distance accurately by varying the decision level of an infinite distance decision circuit according to the brightness of a subject automatically, and reducing error decisions due to the influence of noise when the brightness is high and preventing a decrease in the sensitivity of infinity decision making operation when the brightness is low. CONSTITUTION:A pulse from a light emitting element 1 is reflected by the subject to strike photodetecting elements 2a and 2b. Their photocurrent outputs are sent to light metering circuits 14 and 13 and the logarithmic compression outputs of them are outputted. The output signal of the photodetecting element 2a which indicates the brightness of the subject is applied to a bias circuit 27 to control the level of an infinite-distance decision signal. When the subject brightness signal is below the level of the infinite-distance decision signal, an infinite distance signal 57 is outputted. The output 62 of the 2nd light metering circuit 14 is inputted to a differential amplifier circuit 15 to subtracts one output from the other. The difference between the logarithmic compression outputs, i.e. ratio P2a/P2b of outputs of the photodetecting elements 2b and 2a is calculated. Consequently, an accurate infinite distance decision is made accurately regardless of the brightness.

Inventors

• 👤 Motonobu Matsuda
• 👤 松田　元伸
• 👤 Motohiro Nakanishi
• 👤 基浩 中西
• 👤 Yoshihiro Tanaka
• 👤 良弘 田中

Bibliographic Details