Method and apparatus for liquid-developing latent electrostatic images

Abstract

In an electrostatic copier having an applicator electrode positioned closely adjacent but not touching the photoconductive surface on which there is a latent electrostatic image to be developed. The surface of the latent image and the surface of the applicator electrode move at the same speed, or the electrode may move at a greater speed. The electrode and the photoconductor are spaced from each other by a gap in the order of between three and six mils. The applicator roller is mounted with its lower segment immersed in a tank containing a developing liquid bearing charged toner particles. There is a mechanism for increasing the liquid to the gap, such as a drive for speeding the rotary electrode to more than the photoconductor speed. After the latent image has been developed, a metering roller, which is a roller whose surface moves in the direction opposite to the surface of the photoconductor, meters or dynamically removes a portion of the liquid from the developed image. The freshly developed image is then transferred to a carrier sheet. An arcuate field electrode is positioned between the metering station and the transferring station. The field electrode is biased to a potential of a sign opposite to the charge of the toner particles.