Masahiro Wanou

Toner-size effect on image density

We studied the optical image density of nonfused toner images on paper as a function of toner mass, focusing on the influence of toner particle size on image density, which we studied both theoretically and experimentally. Four different sizes from the same bulk were used to form the solid image. The toner mass required to obtain sufficient image density decreases with particle size. We defined the normalized number oftoner layers, which determines image density regardless ofparticle size. Using mean toner sizes calculated from a cross section ofparticles, we found that theoretical and experimental results agreed well. These results will be useful in developing high-quality electrophotographic printers.

Conductive fur brush charging of a dielectric surface

A dielectric surface is charged without a corona discharge using a conductive fur brush to which an electrical potential of several hundred volts is applied. The fur brush, which consists of 10- mu m-thick conductive fiber, lightly touches the surface of the (Mylar film or photoreceptor) dielectric. It is clear that brush charging is accomplished by direct charge transfer, gas discharge, and triboelectric charging. The direct charge transfer, which is the primary charging process, is analyzed using an ohmic contact model. The charge potential is nearly proportional to that of the brush. When the charging time is longer than 0.3 s, the charged potential on the surface photoreceptor saturates at almost that of the brush, the difference being less than 50 V. This is about the same as in corona charging. Brush charging is, therefore, useful as a low-voltage charging technique. >