Browse Prior Art Database

DUAL ELECTROSTATIC BRUSH CLEANER FOR CLEANING MULTIPLE TONER TYPES

IP.com Disclosure Number: IPCOM000026242D
Original Publication Date: 1990-Dec-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 4 page(s) / 298K

Publishing Venue

Xerox Disclosure Journal

Abstract

In electrophotographic applications such as xerography, subsequent to development and transfer of a latent electrostatic image, some toner invariably remains on the charge retentive surface, it being held thereto by relatively high electrostatic and/or mechanical forces. It is essential for optimum operation that toner remaining on the surface be cleaned thoroughly therefrom.

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XEROX DISCLOSURE JOURNAL

DUAL ELECTROSTATIC BRUSH Proposed Classification CLEANER FOR CLEANING U.S. C1.355/303 MULTIPLE TONER TYPES
Nero R. Lindblad
Darryl L. Pozzanghera

Int. C1. G03g 21/00

To

1B

/

FIG. IA

From

1A

FIG. IB

XEROX DISCLOSURE JOURNAL - Vol15 No 6 NovembedDecember 1990 463

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DUAL ELECTROSTATIC BRUSH CLEANER FOR CLEANING MULTIPLE TONER TYPES(Cont'd)

In electrophotographic applications such as xerography, subsequent to development and transfer of a latent electrostatic image, some toner invariably remains on the charge retentive surface, it being held thereto by relatively high electrostatic and/or mechanical forces. It is essential for optimum operation that toner remaining on the surface be cleaned thoroughly therefrom.

A commercially successful mode of cleaning employed in automatic electrophotographic applications utilizes a brush with soft conductive fiber bristles. While the bristles are soft, they are suffTciently firm to mechanically remove residual toner particles from the charge retentive surface. In addition, a voltage is applied to the fibers, so that the fibers electrostatically attract toner particles. Many cleaning arrangements combine a preclean charge leveling arrangement, typically a corona generator, upstream from the electrostatic cleaning brush.

In highlight color applications, where toners having different triboelectric characteristics are deposited on a charge retentive surface in imagewise configuration, it is difficult to derive a set point at which the conductive fibers may be appropriately biased for the removal of all types of toner. Thus, for example, in a highlight color application similar to that described in U.S. Patent No. 4,868,608 to Allen, Jr. et al., for example, colored toner is used having a preferred negative polarity, i.e., the red toner charges negatively with carrier in the developer housing. Black toner in such an arrangement has a preferred positive polarity, and will charge positively with carrier in the developer. Thus, in such a device there are two polarities of residual toner which must be removed from the charge retentive surface subsequent to image transfer. It has been determined that red toner in such an arrangement is more easily cleaned with a negative preclean treatment and positive brush fiber bias. By contrast, black toner in such an arrangement is most easily removed from the charge retentive surface with a positive preclean treatment and a negative brush bias. It will be appreciated that with a single electrostatic brush cleaner, biasable to only a single voltage, achieving both of these requirements for optimum red and black toner cleaning is almost impossible.

Accordingly, the present invention provides an improved cleaning arrangement in an electrophotographic device using toner types of different tribocharging characteristics, in which residual toner to be cleaned from a charge retentive su...