Comparison of the electric fields of electrophotography and contact electrography

In order to improve the quality of text and graphic printers, companies have increased the resolution and decreased the diameter of toner particles in powder marking technologies. We have been developing a new electrographic printing technology in which the latent image is formed by contacting a write head with many metal fingers to square metal pads on 50 μm centers (500 dpi) fabricated on an insulating cylinder. This system has demonstrated the ability to print for the first time, to our knowledge, in any powder marking system, both black and white single pixels at 500 dpi using normal 9 μm diameter toner. This paper focuses on an analysis of the reasons for the improved image quality for this new technology. A comparison with electrophotography shows that the main difference is the better defined electric field originating from the sharp borders of the metal pixels as compared to the Gaussian beam profiles of electrophotographic exposure devices.