Exposure correcting device

Details Exposure correcting device Exposure correcting device

1980-10-22

1983-04-19

Mathews, Alan

Photocopying

Projection printing and copying cameras

Illumination systems or details

355 51, G03B 2772

Patent

active

043803903

ABSTRACT:
A light-shield plate for correcting the ununiform exposure distribution in an original reading apparatus for example a facsimile resulting from so-called cosine fourth power rule is composed of an easily produceable single member having an arc of a radius R and is positioned in front of or behind an imaging lens at an axial distance L from the lens and at a perpendicular distance H from the center of the arc to the optical axis in such a manner as to be parallel to the light beam entering or emerging from the lens corresponding to the longitudinal direction of the illuminated area on the original and as that the amounts L, H and R are selected to satisfy a certain relationship.

REFERENCES:
patent: 3469916 (1969-09-01), Sloan
patent: 3926518 (1975-12-01), Berry et al.
patent: 3967894 (1976-07-01), Tsilibes
IBM Technical Disclosure Bulletin, "Variable-Aperture Stop for a Reciprocating Lens Copier Design", vol. 17, No. 4, Sep. 1974, Smith.

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