Air breakdown charge and development image forming method and apparatus using image area centered patches of toner

摘要

A method and apparatus for producing high quality liquid toner images in an electrostatic printing machine. The method using the apparatus includes selectively coat a photoreceptor only in selected image area centered portion of the photoreceptor surface thereby forming an image area centered patch of toner with developing material; image- wise exposing each such portion; patch of toner. The method using the apparatus next includes forming a final toner image from each image area centered patch of toner using an air breakdown charge development (ABCD) assembly. The ABCD assembly includes a relatively large magnitude voltage biasing source, and a nip forming roll coupled thereto and forming a toner solids recharging nip with the photoreceptor, for image- wise recharging of the single polarity toner solids coating each image area centered patch of toner, by inducing an air breakdown electrical discharge in which free mobile ions are introduced into the vicinity of each image area centered patch of toner. The latent image underlying each image area centered patch of toner cooperates with the large magnitude voltage biasing source to cause free mobile ions to flow to the toner solids of each image area centered patch of toner in an image- wise manner corresponding to the underlying latent image. This, in turn, leads to image-wise recharging of the toner solids of each image area centered patch of toner in which toner solids in image areas of each patch then have a first polarity, and toner solids in background areas thereof then have a second and relatively opposite polarity. The method of the present invention then includes separating the image area toner solids of each patch of toner from the background area toner solids thereof, thereby resulting in an efficiently produced, quality toner image with significantly reduced non-development marking material generated and requiring removal.