DIGITAL IMAGE-SETTER UTILIZING HIGH-RESOLUTION MICRO-DISPLAY

摘要

A digital image-setter utilizing a micro-display (10) which produced, offset-printing plates with high print resolution and negligible smearing in an acceptably short time. The device, consisting of a drum (2) carrying a photo-sensitive offset printing plate medium (3) and an external, axially moving image projector (1), using a high-resolution, high-efficiency, reflective LC Spatial Light Modulator (SLM) as a micro-image source. The LC SLM is illuminated by a high-power, source of pulsed light (11) in the visible or near ultra-violet and the image is focused onto the photo-sensitive offset plate medium (3) by means of an optical projection system (13). On-the-fly adjustment may be made to the resolution of the final image. The source of pulsed light may be either a flash lamp or a continuous light source directed through a combination of two crossed, beam splitters (14, 16) and a polarization rotator (19). 98 % uniformity of illumination may be achieved by making use of the 64-level or more gray-scale capability of the SLM. Another version of the invention also utilizes auxiliary illumination material as that medium. All the components of the device are commercially available.