Toner transferring method and apparatus

摘要

Electrostatographic apparatus and method for transferring charged toner present in an image configuration on an insulating layer bearing an electrostatic latent image are illustrated. The technique involves forming a sandwich comprising the insulating layer with a conductive substrate bearing a toner image on its surface, a copy substrate, a dielectric layer, and a conductive electrode together with means for applying a potential to the conductive electrode after the sandwich is formed, the potential being of a magnitude sufficient to create an electric field to transfer toner from the insulating layer to the copy substrate. The apparatus also includes means to discharge the electrostatic latent image on the insulating layer before separation of the sandwich and means to strip the copy substrate from the dielectric layer while the field is applied to provide a toner image on the copy substrate. In a preferred embodiment the conductive electrode comprises a cyclindrical roll having a circumference at least equal to the length of the image on the insulating layer, and the sandwich is formed by wrapping a photoconductive insulating layer bearing a toner image in contact with a copy sheet around the roll with the dielectric layer forming a blocking electrode in between the insulating layer and the conductive electrode. During the wrapping step the translucent back of the photoconductive layer is exposed to discharge the electrostatic latent image on the photoconductive layer and once the sandwich is formed it is unwrapped to separate the copy sheet from the dielectric layer.