Contact electrostatic printing image forming method and apparatus using image area centered patch of tonerpatches of toner
 A printing machine and method for efficiently forming toner images such that a quantity of unused toner applied to a photoreceptor of the machine is significantly diminished are provided. The printing machine and method include a movable photoreceptor having a photoconductive surface for supporting electrostatic charge; a first charging device for selectively charging only scattered portions of the surface of the photoreceptor; a liquid developer material supply and application apparatus for applying a coat of charged toner solids having a single polarity onto each charged selected scattered portion, thereby forming an image area patch of toner; an exposure device for image-wise exposing each charged selected scattered portion to form a first latent image therein; and a contact electrostatic printing (CEP) assembly including a conductive (CEP) roll and a bias source coupled thereto, for applying compressive and tensile forces to the image area centered patches of toner moving through an image processing nip formed by the photoconductive surface of the photoreceptor and the conductive CEP roll, wherein the bias source cooperates with a charge pattern of the image area centered patches of toner to generate image-wise electric fields within the image processing nip, and the image-wise electric fields together with the compressive and tensile forces, enable easy separation of background area toner solids from image area toner solids of the image area centered patches of toner, and onto the CEP roll; thereby resulting in an efficiently produced, quality toner image with significantly reduced non-development marking material generated and requiring removal. 
Xerox Corporation
G G
G03G G03G
inventional inventional
Chu-Heng Weizhong
Liu Zhao