PHOTOCOPIER EXPOSURE CONTROL

摘要

An automatic exposure control for a reflex photocopier wherein a light-transmissive photosensitive film is moved through an exposure area in intimate contact with an original document to differentially desensitize the photosensitive film according to the differential reflectivity of the original document. The exposure control continuously collects a plurality of samples of light representative of the sum of the intensity of the light from the exposure light source and the intensity of the light reflected from the portion of the original document at the exposure area, each sample representing the sum over a portion of the exposure area. The samples of light are simultaneously transmitted, their intensities are averaged and the output from the exposure light source is controlled in response to the average intensity to maintain the intensity of the light which exposes the photosensitive film a predetermined constant.