Distance measuring device of camera

Details Distance measuring device of camera Distance measuring device of camera

1992-05-22

1993-04-06

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

354403, G01J 120

Patent

active

052006026

ABSTRACT:
Pulse light is emitted by controlling the operation of a driving circuit by a microcomputer and is irradiated to a photographed object. Light reflected on the photographed object is received by a semiconductor optical position detector. First and second current outputs having a current ratio are inputted to first and second detecting circuits within an AF signal processing circuit in accordance with a light receiving position corresponding to a distance of the object. The first and second detecting circuits logarithmically transform changing amounts of the first and second current outputs. A differential detecting circuit calculates a difference between changing amounts of outputs of the first and second detecting circuits, and outputs a distance measuring signal to the microcomputer. A light receiving element measures the intensity of external light and an error in the distance measuring signal caused by the external light is corrected by the microcomputer on the basis of the above results.

REFERENCES:
patent: 4527892 (1985-07-01), Yamane et al.
patent: 4601574 (1986-07-01), Yamane et al.
patent: 5128529 (1992-07-01), Nagaoka et al.

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