Focus detection apparatus employing image height correction

Details Focus detection apparatus employing image height correction Focus detection apparatus employing image height correction

1983-11-17

1986-09-23

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

250204, G01J 120

Patent

active

046137483

ABSTRACT:
In a method for detecting a focus condition which utilizes an image lateral shift between images formed alternately on light receiving elements substantially arranged on a focal plane, an incident light unbalance on the light receiving elements caused by an image height effect for respective light receiving elements and a relative positional shift between a pupil dividing means and the light receiving element is corrected by using correction coefficients previously stored in a digital memory. The correction coefficients for respective light receiving elements are derived from inversion outputs of respective light receiving elements under the condition such that a uniform light flux is projected onto the imaging optical system before effecting an actual focus detecting operation. It is possible to make the optical system small in size and inexpensive in cost, because it is not necessary to use an additional optical system. In addition, it is possible to detect the focus condition in a highly accurate manner, since no incident light unbalance occurs.

REFERENCES:
patent: 4306143 (1981-12-01), Utagawa et al.
patent: 4441096 (1984-04-01), Evanchuk
patent: 4447719 (1984-05-01), Ogasawara
patent: 4500189 (1985-02-01), Aoki

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