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SCHEME FOR OBTAINING CONSTANT FRANSFER FIELD INDEPENDENT OF PAPER WIDTH OR OTHER PROPERTIES

IP.com Disclosure Number: IPCOM000024144D
Original Publication Date: 1979-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 256K

Publishing Venue

Xerox Disclosure Journal

Abstract

In the transfer step in the xerographic process, it is advisable to use a charging device which supplies a constant, dynamic current so that a constant surface charge density is applied to the medium to which transfer is to be effected. This provides a transfer field practically constant in time, given that steps have previously been taken to ensure that the incoming toned photoreceptor is at an

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XEROX DISCLOSURE JOURNAL

SCHEME FOR OBTAINING CONSTANT Proposed Classification ~ U.S. Cl. 355/3 CH

mt. Cl. G03g 15/00

~iay

B. E. Springett

3b

In the transfer step in the xerographic process, it is advisable to use a charging device which supplies a constant, dynamic current so that a constant surface charge density is applied to the medium to which transfer is to be effected. This provides a transfer field practically constant in time, given that steps have previously been taken to ensure that the incoming toned photoreceptor is at an

approximately uniform potential, One of the difficulties with this arrangement is that the paper (or other medium) which is to be transferred to has widths which can be differnt from the length of the transfer charging device. This gives rise to a

phenomenon known as "end leakage." That is, due to the fact that the effective dielectric properties of the medium beneath the charging device are not the same

all along the length of the device, the current divides between, for example, paper and photoreceptor in a way which depends on the paper properties, Thus, the

current delivered to the paper is not independent of the paper. The net result is a transfer efficiency and copy quality which depends upon paper type and paper

width. The implication for duplex copying where paper resistivity can change more than two orders of magnitude are obvious.

This situation can be largely avoided by the charging device shown in the figure. A dicorotro...