Focus detecting device and auxiliary illuminating device therefo

Details Focus detecting device and auxiliary illuminating device therefo Focus detecting device and auxiliary illuminating device therefo

1988-05-20

1990-09-18

Perkey, W. B.

Radiant energy

Ionic separation or analysis

Static field-type ion path-bending selecting means

2504951, 250504R, 2502014, G03B 300, G01J 100

Patent

active

049581805

ABSTRACT:
A focus detecting device for detecting a focus condition of a photographic lens by receiving light coming from a plurality of focus detecting area and auxiliary illuminating device therefor. The illuminating device is provided with a light source, a projection pattern disposed just before the light source for providing a sufficient contrast onto an object and a projection lens. The light source is composed of plural condenser lenses arranged in a row and plural light emitting elements arranged behind the condenser lenses at intervals wider than the spacing of adjacent condenser lenses, whereby an object of a wide range is illuminated uniformly. The projection pattern comprises small-size patterns suitable for photographic lenses of long focal lengths, arranged centrally of the projection pattern, and large-size patterns suitable for photographic lenses of short focal lengths, arranged in the outer peripheral portion of the projection pattern. Further, the projection pattern has a curved shape to compensate astigmatism characteristics of the projection lens.

REFERENCES:
patent: 4544252 (1985-10-01), Tsukamoto
patent: 4801963 (1989-01-01), Koyama et al.

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