Exposure control system for photographic copying

Details Exposure control system for photographic copying Exposure control system for photographic copying

1976-02-11

1977-05-24

Hix, L. T.

Photocopying

Projection printing and copying cameras

Illumination systems or details

355 77, 356226, 361175, G03B 2732, H01H 4724, G01J 144, G03B 2772

Patent

active

040251900

ABSTRACT:
An exposure control for automatically controlling the duration of the exposure time for a photographic material to be printed. The light intensity is sensed by a sensor which could be either of the photoresistive or the photovoltaic type. A range control controls both the light sensor circuit and a timer control. The range control permits to return the indicator to a permanent mark despite variations of the lens aperture, negative density, degree of enlargement and the like, while simultaneously increasing or decreasing the length of a standard timing signal. The timing signal in turn controls the printer lamp to determine the exposure time.

REFERENCES:
patent: 2354544 (1944-07-01), Rath
patent: 2501365 (1950-03-01), Varden
patent: 3533705 (1970-10-01), Fukushima
patent: 3790789 (1974-02-01), Takahashi et al.
patent: 3947112 (1976-03-01), Reissig

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