Photocopying – Projection printing and copying cameras – Illumination systems or details
Patent
1977-10-04
1980-12-02
Hix, L.T.
Photocopying
Projection printing and copying cameras
Illumination systems or details
355 83, G03B 2778
Patent
active
042368162
ABSTRACT:
A device giving automatically correct exposure times for printing photographs, based on the principle of reflected-light measurement and integration, with a light measuring probe which may project a cone of light on the printing plane to precisely show the location and the size of the measuring area which can thus be controlled and varied at will. The electronic circuit comprises a luminous over-range indicator lighting up when the device is operated in conditions of too low or too high illumination for the circuit to work within its limits of linear operation. A potentiometer can be set for the sensitivity of the photographic material used and a single switch allows both interruption of already initiated exposure cycles at any moment, and switching off the darkroom safelight at the same time powering the enlarger when it is wished to control light conditions and/or measuring zone location before printing, in order to avoid any chance of incorrect exposure times.
REFERENCES:
patent: 2952780 (1960-09-01), Rogers, Jr.
patent: 3790789 (1974-02-01), Takahashi et al.
patent: 3967288 (1976-06-01), Yamamoto
patent: 4027314 (1977-05-01), Iguchi et al.
patent: 4041504 (1977-08-01), Iodvalkis et al.
Brady W. J.
Hix L.T.
Levine Alan H.
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