APPARATUS FOR THE PRODUCTION FROM AN ORIGINAL OF A PRINTING PLATE READY FOR PRINTING

摘要

An electrophotographic apparatus for producing printing masters utilizing modulated laser light as the exposure source and a continuous process for producing such printing masters involving the steps of plate conveyance, synchronous charging and exposure, and electrostatic development and fusing of electrophotographic printing masters suitable for use in offset or lithographic printing processes. The apparatus comprises a transport system for sequentially conveying printing masters to the exposure platen which retains the masters in a fixed plane for synchronous charging and exposure, utilizing as a light source, a modulated laser beam. The optical and deflecting components of the exposure system are mounted in a moveable carriage member adapted to traverse a plane substantially parallel to the plane of the exposure platen such that the exposure laser will raster scan the platen area. The charging coratron is also preferably mounted on the moveable carriage such that the sequence of charging the electrophotographic master and exposure thereof to the raster scan of the exposure laser are synchronous. The apparatus employs an exposure laser having a power of about less than 1 watt, but sufficient power to provide a light energy on the photoconductive surface of the printing master of at least about 2x10-3 millijoules/cm2 under operating conditions.