US 5,053,821 AGranted

Electrophotographic image forming apparatus using photoconductive toner

AssigneeSeiko Epson Corporation, A Corporation of Japan

InventorsMasanao Kunugi, Hajime Kurihara, Teruyuki Mizumoto

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Abstract

A photoconductive image forming apparatus in which charged photoconductive 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.

Claims20

Dependent claims

A photoconductive image formation apparatus comprising:

a transparent insulating image forming substrate including a transparent conductive layer and a transparent insulating surface disposed thereon;
developer means including photoconductive toner particles and electroconductive carrier particles on an electroconductive transport support for triboelectrically charging the toner particles on the electroconductive transport support, the developer means positioned adjacent to the image forming substrate so that the charged toner particles on the electroconductive transport support contact the image forming substrate, the toner particles having lowered resistivity when exposed with an appropriate wavelength;
exposure means for exposing the toner on the electroconductive transport support contacting the substrate, through the substrate, with an exposure of an appropriate wavelength, corresponding to an image;
bias voltage means for maintaining a DC bias voltage between the electroconductive transport support and the image forming substrate, the voltage too low to reverse the charge of unexposed toner, but high enough to reverse the charge of exposed toner, so that exposed toner from the electroconductive transport support will adhere to the image forming substrate in the form of an image;
and
transfer means for transferring toner from the image forming substrate to a transfer medium.

3 more elements

Dependencies are inferred from the claim text.