US 4,921,768 AGranted

Electrophotographic image forming

AssigneeSeiko Epson Corporation

InventorsMasanao Kunugi, Hajime Kurihara, Teruyuki Mizumoto

Life of this patent

Estimating the term…

Loading patent…

Abstract

A photoconductive image forming method in a which charged toner contacts a transparent insulating substrate and is exposed from within the substrate. Exposure reduces the resistivity of the toner so that its charge can be reversed by a bias voltage and the exposed toner will adhere to the image forming substrate simultaneously with exposure and then transfer to a transfer medium. In an alternative embodiment of the invention, a layer of toner is applied to an electroconductive substrate and the toner layer is exposed with a latent image. The charge of the exposed toner is reversed and the exposed toner is removed by an intermediate toner removal device. The remaining toner is then transferred to a transfer medium. Toner suitable for use includes azo-type metal containing black dyes which do not absorb the exposure and can be sensitized to the near infrared region. Multicolor toners, each sensitized to a different exposure wavelength are provided so that a single multiple wavelength exposure and a single development can be used to form multicolor images.

Claims11

Dependent claims

A photoconductive image forming method, comprising:

charging a quantity of photoconductive toner in which resistivity is reduced on exposure and forming a thin layer of the charged toner with electroconductive charge carriers on an electroconductive transport support;
contacting the charged photoconductive toner on the electroconductive transport support to a transparent insulating image forming substrate and applying a DC bias voltage between the transparent insulating image forming substrate and the electroconductive support, the voltage insufficient to reverse the charge of unexposed toner but high enough to reverse the charge of exposed toner;
exposing the photoconductive toner on the electroconductive transport support and in contact with the transparent insulating image forming substrate through the substrate to reduce the resistance of the exposed toner so that the bias voltage will selectively reverse the charge of exposed toner on the electroconductive transport support and cause charges to flow from the charge carriers to the toner to selectively transfer and adhere the exposed toner from the electroconductive transport support to the image forming substrate in the form of the image;
and
transferring the exposed toner adhering to the image forming substrate in the form of the image to a transfer medium.

2 more elements

Dependencies are inferred from the claim text.