ELECTROPHOTOGRAPHIC COPIER WITH VARIABLE ORIGINAL DOCUMENT TO IMAGE SIZE RATIO

摘要

An electrophotographic copier, of the type in which a line of light scans the original document and in which the lens is movable to effect variations in the ratio of original document to image size, has a field stop mask positioned to intercept light from a document being scanned before it is passed to the lens. The mask has an aperture configured to minimise image intensity variations caused by changes in the ratio, to correct for lens cos4 losses and to compensate for uneven intensity along the line of light scanning the document.