Automatic exposure control system for flash exposure photocopier

Details Automatic exposure control system for flash exposure photocopier Automatic exposure control system for flash exposure photocopier

1988-01-21

1989-05-16

Prescott, A. C.

Photocopying

Contact printing

Light boxes

355 67, 355 68, 355 14R, 355 14D, 355214, 355246, 340641, G03G 1500

Patent

active

048314102

ABSTRACT:
A flash exposure photocopier provides a mechanism for automatically controlling photoreceptor exposure levels to compensate for the effects of documents having backgrounds of different densities. A photosensor and lens assembly is located within a flash housing in a position whereby a large portion of the document is imaged by the lens onto the surface of a chip having a plurality of individual photosensors contained thereon. The outputs of each photosensor are integrated and applied to a comparator set at a particular reference level. The comparator output controls the duration of the flash source so as to quench lamp operation when an input level is reached corresponding to the particular reference level set. The integrated photosensor outputs are also summed and a signal representing their average value is compared to the signal which triggers the comparator. The ratio of these signals is used to identify documents with high area coverage and hence high toner usage. The toner dispensing rate is then regulated accordingly.

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patent: 4796065 (1989-01-01), Kanbayashi

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