Electro photographic recording material with compensa - tion for uneven exposures

摘要

Photo-conductive layer with sensitivity inversely proportional to intensity of incoming signals evens out differences in signal intensity caused by falling off of brightness towards edges, vignetting by aperatures and diaphragms, and brightness loss due to Lambert's law. Continuous grey filters near image plane are technically difficult to handle. Differential charging of electrophotographic materials requires complicated charging devices. Thickness of photoconductive layer is therefore used for compensation. To obtain convex or concave layers, selenium is applied by vapour deposition on plates cylinders or sheets by positioning depositors in such an order as to obtain required shape, or by shaping semiconductor paste in binder. Advantage of process is its adaptability to non-rotation symmetric radiation intensity distribution.