Electrostatic device for charging a photosensitive surface

Abstract

In an electrostatic device that uses a resistance film for electrifying a latent image holder in printing devices, such as a photo-copier or a facsimile, at least one electrode borders the resistance film. The electrostatic device confronts a latent image holder, having a cylindrical shape, across a narrow gap and along the length of the latent image holder. With this structure, applying D.C. voltage to the electrode electrifies the latent image holder via the resistance film. Since the resistance film and the electrode overlap each other, the potential on the latent image holder is dependent on the surface resistance rather than the volume resistance of the resistance film giving the electrostatic device an immunity from nonuniformity or flaws in the surface of the resistance film. In addition, an electrostatic device of this invention has a structural advantage over conventional scorotron devices. Since there is no conductive member for retrieving current, and current supplied to the electrode is discharged at the narrow gap with a very small leakage, the electrostatic device has high efficiency in current use, resulting in a substantially smaller amount of ozone generated in operation.

Dependencies are inferred from the claim text.