Optics: measuring and testing – Range or remote distance finding – With photodetection
Patent
1992-10-08
1993-10-26
Perkey, W. B.
Optics: measuring and testing
Range or remote distance finding
With photodetection
356 4, 2502016, G03B 1336, G01C 308, H01J 4014
Patent
active
052570614
ABSTRACT:
A range finder circuit for a passive-type autofocusing device includes three line photosensors. Secondary differences of their output signals and zero-cross points of these secondary differences are computed and detected so long as these zero-cross points are those appearing when primary differences derived from computation of the secondary differences have absolute values larger than a predetermined value. The range to the scene is computed based on the amount of shifting of these signals into coincidence so that substantially no erroneous range finding occurs even when two objects composing the scene overlap each other. In a preferred embodiment also, signals from pixels of each photosensor are smoothed so that no erroneous range finding occurs even when the scene has on the surface thereof a fine repetitive pattern. The range finder circuit also responds to the output signals of the sensors to initiate write-in of zero-cross point data into associated zero-cross memory circuits which can be electrically position-adjusted so that the range to the scene can be computed substantially without error even when there is a certain error involved in mounting of the photosensors.
REFERENCES:
patent: 4373791 (1983-12-01), Araki
patent: 4387975 (1983-06-01), Araki
patent: 4575626 (1986-03-01), Oinoue et al.
patent: 4616264 (1986-10-01), Pshtissky
patent: 5070353 (1991-12-01), Komiya et al.
patent: 5189461 (1993-02-01), Ishiguro
U.S. patent application Ser. No. 07/834,636, filed Feb. 12, 1992 entitled Range Finder For Passive Type Autofocussing Device.
Fuji Photo Optical Co., Ltd.
Perkey W. B.
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