Browse Prior Art Database

TONER MIXTURE FOR IMPROVED IMAGE QUALITY

IP.com Disclosure Number: IPCOM000023465D
Original Publication Date: 1977-Oct-31
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 278K

Publishing Venue

Xerox Disclosure Journal

Abstract

With commercial toners used in xerographic development, there is a suppression of background during the transfer step be-cause the mass transfer efficiency in areas of low image density is about 45% compared to about 75 - 90% in areas of high density. This can be overcome by using a toner compri-sing a mixture of different size toner particles, that is, a bi-modal size distribution.

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XEROX DISCLOSURE JOURNAL

TONER MIXTURE FOR IMPROVED Proposed Classification
IMAGE QUALITY U.S. Cl. 96/1
Narendra S. God tnt. Cl. G03g
Paul R. Spencer

With commercial toners used in xerographic development, there
is a suppression of background during the transfer step be-
cause the mass transfer efficiency in areas of low image
density is about 45% compared to about 75 - 90% in areas of
high density. This can be overcome by using a toner compri-
sing a mixture of different size toner particles, that is, a
bi-modal size distribution.

A preferred mixture of toner comprises particles of about 10 - 15 microns diameter and particles of about 4 microns or less.
An image developed with this mixture consists of a monolayer
of the fine particles with the larger toner particles thereon.
During transfer, the larger diameter toner particles transfer
easily, and the finer particles forming the monolayer do not
transfer. Since the residual toner in the image area consists
of the small size particles, the mass fraction of the toner
left on the photoreceptor is very small. Because of this high
mass transfer efficiency, 75 - 90% transfer efficiency is
achieved in the image area by applying smaller transfer
forces, such as electric fields. The smaller forces required
for transfer when bi-modal size distribution is used for the
toner reduce background transfer of toner without decreasing
the density of the transferred image.

This improved toner mixture also permits the use of a toner
having a particle siz...