Browse Prior Art Database

Controlling Light Environment in a Copier

IP.com Disclosure Number: IPCOM000084858D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Paterson, RL: AUTHOR [+2]

Abstract

Multilayered photoconductor elements are sometimes utilized in electrophotographic copying devices. Typically, such a multilayered photoconductor is comprised of a conductive substrate, a layer of photoconductor or charge generation material coated on the conductive substrate, and a separate charge transport layer overcoated on the charge generation layer. Such a multilayered element is utilized in a copying device by uniformly charging its surface either negatively or positively in the dark, and then selectively exposing it to light.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Controlling Light Environment in a Copier

Multilayered photoconductor elements are sometimes utilized in electrophotographic copying devices. Typically, such a multilayered photoconductor is comprised of a conductive substrate, a layer of photoconductor or charge generation material coated on the conductive substrate, and a separate charge transport layer overcoated on the charge generation layer. Such a multilayered element is utilized in a copying device by uniformly charging its surface either negatively or positively in the dark, and then selectively exposing it to light.

The portions of the charge generating layer which are exposed to light generate charge pairs in the form of holes and electrons, one of which is capable of migrating through the charge transport layer to neutralize the opposite charge which is present at the surface. The charge transport layer is normally selective, allowing the migration of only holes or electrons.

Unfortunately, many charge transport materials also display the ability to generate charges when exposed to some wavelengths of light. Therefore, it is not unusual for hole and electron pairs to be generated in a charge transport layer, when it is exposed to either a broad spectrum of light or a specific range of wavelengths. If the charge transport layer is a hole transport material, then the holes thus generated in situ are easily dissipated by migration to the surface of the photoconductor element.

Similarly, if the charge transport material is an electron transport material, the electrons generated in situ are easily dissipated by migration to the surface of the element. However, in either case, the species of charge which does not tend to migrate through the transport layer remains in a relatively fixed position within the charge transport layer.

As these trapped charges buildup within the element they change the electrical characteristics of the element. The typical response to this charge buildup is to adjust the sensitivity of the copying device to compensate for this phenomena. However, during a period of prolonged nonuse, such as overnight, the charge buildup tends to dissipate. Then, when the copier is utilized, after the charge buildup has been dissipated, the machine adjustments which had been made to compensate for the charge buildup effect the voltage characteristics of the system which, in turn, effects the copy quality of the copier.

One means for avoiding this problem is to control the light environment in the copier to which the photoconductor is exposed, and thus avoid the generation of charge pairs in the charge transport layer. This is accomplished by determining the sens...