Treating an electrostatic latent image with charge of same polarity as that of image areas

Abstract From the Canadian patent

To improve the quality of copies made on an electrostatic reproduction machine, a post exposure predevelopment corona generating device is used to treat an electrostatic latent image on a photoreceptor. The device deposits a treating charge onto the latent image of the same polarity as the latent image the treating charge being of a magnitude sufficient to lower the charge contrast between the background of the latent image and undesirable low density image areas, but not sufficient to detrimentally affect other areas of the latent image. The treating charge may be varied upwardly or downwardly to obtain the desired result but as, it is varied, an electrical bias applied to a developer is …