Method for liquid development of latent electrostatic images

Abstract

A method for developing a latent electrostatic image by passing the image close to but out of contact with a surface of a liquid developer at a development zone. The values of the magnitude of the charge of the image, the distance between the image segment and the liquid surface at the development zone, and the physical characteristics of the liquid are such that at the development zone the electrostatic field created by the segment of the image at the zone, with or without the assistance of an external electrostatic field impressed upon the development zone, raises pseudopods from the liquid developer surface which extend toward the carrier on which the electrostatic image is present. The pseudopods and/or droplets separated from the tips of the pseudopods leave the liquid surface under the influence of the electrostatic field created by the image segment. Where there is no latent image, the voltage, the gap and the physical characteristics of the developing liquid are such that no developing liquid reaches the carrier, so that these uncharged segments of the carrier are not touched by the tips of the spikes or the droplets and, hence, remain dry and not colored by the color of the liquid if the liquid is colored. These dry spots constitute the background against which the developed latent image is seen. Such background, due to the balancing of the factors mentioned, remains in its virgin state and provides an excellent contrast for the colored developed image.