Photographic copying apparatus

Details Photographic copying apparatus Photographic copying apparatus

1978-08-15

1980-08-19

Wintercorn, Richard A.

Photocopying

Projection printing and copying cameras

Focus or magnification control

352140, 354 25, 355 74, G03B 2734, G03B 2740

Patent

active

042181330

ABSTRACT:
A photographic copying apparatus wherein a composite mask is installed between the plane of photographic paper and a variable-focus optical unit which images a light source or an original into the plane of photographic paper. The movable sections of the mask carry pairs of photodiodes. A control unit adjusts the optical unit when the latter projects light onto both photodiodes of each pair in a direction to reduce the projected image and in the opposite direction when none of the photodiodes are illuminated. The adjustment is terminated when the size of the projected image is such that only one diode of each pair is illuminated.

REFERENCES:
patent: 2563892 (1951-08-01), Waller et al.
patent: 2737081 (1956-03-01), Dowling
patent: 3315561 (1967-04-01), Boutique
patent: 3627411 (1971-12-01), Nagel
patent: 3649113 (1972-03-01), Harvey

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