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Field Enhanced Photodischarge for Electrophotography

IP.com Disclosure Number: IPCOM000077500D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 17K

Publishing Venue

IBM

Related People

Seki, H: AUTHOR

Abstract

A process to increase the electrophotographic sensitivity is proposed by application of an external field during exposure to image-wise illumination.

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Field Enhanced Photodischarge for Electrophotography

A process to increase the electrophotographic sensitivity is proposed by application of an external field during exposure to image-wise illumination.

The photodischarge process of a photoreceptor can be described to a first approximation by a relation dV over dt = = q over C(p) fY (V over L) where V is the voltage, q is the charge on a carrier, C(p) is the unit area capacitance of the photoreceptor, f is the photon flux density and Y is the photoinjection efficiency. This shows that the sensitivity of the photoreceptor is essentially determined by the photoinjection efficiency Y. Measurements of Y for an organic photoconductor which is a 1 to 1 molar mixture of polyvinyl carbazole and trinitrofluorenone (1:1 OPC), indicate that Y is strongly field dependent and can be approximated by the relation Y = Y(o)E/m/ where E is the field in the surface of the photoconductor. In the case of 1:1 OPC m is about 1.1 to 1.6 and for amorphous Se this is 0.5. The field decreases as the photodecay proceeds and efficiency also decreases. This loss of efficiency becomes greater with larger m. A process is proposed in which an external field is applied to minimize this loss. In principle, this is done when a transparent electrode is placed above the photoreceptor in the region where the image-wise illumination is incident. Application of voltage to the electrode provides additional field. However, it is necessary to have fields i...