Gray scale and resolution enhancement capabilities of edge emitter imaging stations

Westinghouse has developed a thin film electroluminescent (TFEL) edge emitting imaging station for use in electrophotographic printing. The physical and electrical drive characteristics offer unique opportunities for gray-scale printing and resolution enhancement. The physical dimension of the light-emitting element in the process direction is less than to micrometers . In addition, the light output of the edge-emitting array is not Lambertian but, rather, is highly directed. The majority of light is emitted in a wedge with a 30 deg half angle measured form the plane of the device. The array is activated by an ac waveform. Light emission occurs as the field across the device changes direction. The rise time to peak light emission is a few microsecond(s) and the decay is a few hundred microsecond(s) . This allows an array element to be turned on and off several times during the exposure of a single 300 dot-per-inch pixel in a low-speed printer. This paper provides a detailed description of the physical dimensions, electronic drive system, and light emission characteristics of edge-emitting array. Several print samples are shown illustrating the gray scale and resolution enhancement capabilities.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.