Focus condition detecting device for cameras

Details Focus condition detecting device for cameras Focus condition detecting device for cameras

1984-07-30

1985-07-02

Perkey, William B.

G03B 300

Patent

active

045264589

ABSTRACT:
In a focus condition detecting device wherein an object image formed by an objective lens of a camera is re-imaged as first and second images on first and second photocell arrays through a pair of re-imaging lenses, a pair of plano-convex lenses are used as the re-imaging lenses to improve the accuracy of focus condition detection. The device is formed into a module and the plano-convex lenses are formed on a transparent plate supported on a main body of the module. An extremely thin masking member for blocking a part of light rays incident on the plano-convex lenses to form the first and second images is sandwiched between the transparent plate and a surface of the module main body. This arrangement prevents the masking member from rising and/or warping which otherwise causes inconsistency in luminous levels between the first and second images on the first and second photocell arrays. Various examples of the arrangement of the masking member to prevent its rising and/or warping are proposed.

REFERENCES:
patent: 4189218 (1980-02-01), Saito et al.
patent: 4322616 (1982-03-01), Fukuhara
patent: 4341953 (1982-07-01), Sakai et al.
patent: 4359636 (1982-11-01), Stauffer
patent: 4370551 (1983-01-01), Fukuhara et al.
patent: 4391513 (1983-07-01), Fujiki
patent: 4397547 (1983-08-01), Grassl
patent: 4436395 (1984-03-01), Fukuhara
patent: 4470682 (1984-11-01), Suzuki et al.

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