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COATING PROCESS FOR LAYERED PHOTORECEPTOR

IP.com Disclosure Number: IPCOM000026457D
Original Publication Date: 1992-Feb-29
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 120K

Publishing Venue

Xerox Disclosure Journal

Abstract

Layered photoreceptors, consisting of a thin charge generation layer (CGL) and a thick charge transport layer (CTL), have many advantages over single layer structures. A key to the performance of a layered photoreceptor is a very thin charge generation layer to reduce the distance the photogenerated charge must move and the amount of photogenerated charge that can be trapped in this layer. However, to function as a good generator, the CGL layer must also be optically thick to absorb most of the light during imagewise exposure. These two constraints require the material of the CGL to be highly absorbent, which favors pigments with crystalline forms.

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XEROX DISCLOSURE JOURNAL

COATING PROCESS FOR Proposed Classification LAYERED PHOTORECEPTOR U.S. C1.430/125 Andrew R. Melnyk Int. C1. G03g 21/00

Layered photoreceptors, consisting of a thin charge generation layer (CGL) and a thick charge transport layer (CTL), have many advantages over single layer structures. A key to the performance of a layered photoreceptor is a very thin charge generation layer to reduce the distance the photogenerated charge must move and the amount of photogenerated charge that can be trapped in this layer. However, to function as a good generator, the CGL layer must also be optically thick to absorb most of the light during imagewise exposure. These two constraints require the material of the CGL to be highly absorbent, which favors pigments with crystalline forms.

Although the preferred method of forming the CGL from organic materials is solution coating, the best photogeneration pigments, for example phthalocyanines and perylene amides, are predominantly insoluble and require dispersion in a solvent soluble binder. A solution to this is a hybrid coating process that vacuum deposits the generation layer while solvent coating the other layers.

The superior electrical properties of a vacuum coated CGL to a solvent coated CGL have been demonstrated. However, since most of these CGL's require an adhesive layer which is solvent coated, the process can be costly.

The conducting metal ground plane layer on flexible substrates, such as polyethylene terephthalate, are deposited by vacuum coating. This is followed by a solvent coated blocking and adhesive layers and hence require return of the solvent coated member back to the vacuum coater for the CGL coating pass. These steps increase direct and indirect costs through yield. The latter problem arises because the required additional handling increases the probability for defects.

A solution to the foregoing problems is to vacuu...