Browse Prior Art Database

A.C. BIASED DETONING ROLLS FOR ELECTROSTATIC BRUSH (ESB) CLEANER

IP.com Disclosure Number: IPCOM000027069D
Original Publication Date: 1995-Feb-28
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 198K

Publishing Venue

Xerox Disclosure Journal

Abstract

Electrostatic Brush Cleaning Systems are well known and typically employ a conductive fiber brush, which is biased at some voltage relative to ground so as to be favorable to the electrostatic removal of untransferred charge particles from the photoreceptor 12, as shown in Figure 1. These toner particles 10 are subsequently removed from the conductive fiber brush 20 by means of two bias detoning rolls, 30, 40, a flicker bar 50 and a vacuum manifold 60. The two detoning rolls 30,40 are biased at opposite polarities (with respect to the brush) to achieve detoning of positively charged particles by one detoning roll 30 and negatively charged particles by the other detoning roll 40. (Most particles entering the cleaner are positively charged and can be removed by the detoning roll 30 assembly to remove positive toneddebris. However, to deal with the small fraction of negatively charged particles, a detoning roll 41 assembly to remove negative toneddebris is used.) Because the nips of the detoning roll are necessarily physically separated from one another, there is an opportunity for charge distribution changes during the time it takes a given brush segment to move from one detoning roll 30 to the next 40. As a consequence, toner particles may have low charge when it enters the first detoning roll nip and wrong charge polarity when it enters the second detoning roll ni . Similarly, it may have

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

A.C. BIASED DETONING ROLLS FOR ELECTROSTATIC BRUSH U.S. C1.355/301 (ESB) CLEANER
Geoffrey M. T. Foley
Clark V. Lange
James R. Beachner

Proposed Classification

Int. C1. G03g 21/00

60

10 I

FIG. 1

+v I

FIG. 2

XEROX DISCLOSURE JOURNAL - Vol. 20, No. 1 JanuaryIFebruary 1995 79

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Page 2 of 4

A.C. BIASED DETONING ROLLS FOR ELECTROSTATIC BRUSH (ESB) CLEANER (Cont'd)

Electrostatic Brush Cleaning Systems are well known and typically employ a conductive fiber brush, which is biased at some voltage relative to ground so as to be favorable to the electrostatic removal of untransferred charge particles from the photoreceptor 12, as shown in Figure 1. These toner particles 10 are subsequently removed from the conductive fiber brush 20 by means of two bias detoning rolls, 30, 40, a flicker bar 50 and a vacuum manifold 60. The two detoning rolls 30,40 are biased at opposite polarities (with respect to the brush) to achieve detoning of positively charged particles by one detoning roll 30 and negatively charged particles by the other detoning roll 40. (Most particles entering the cleaner are positively charged and can be removed by the detoning roll 30 assembly to remove positive toneddebris. However, to deal with the small fraction of negatively charged particles, a detoning roll 41 assembly to remove negative toneddebris is used.) Because the nips of the detoning roll are necessarily physically separated from one another, there is an opportunity for charge distribution changes during the time it takes a given brush segment to move from one detoning roll 30 to the next 40. As a consequence, toner particles may have low charge when it enters the first detoning roll nip and wrong charge polarity when it enters the second detoning roll ni . Similarly, it may have

reaches the second detoning nip. It can be extremely difficult trying to insure that neither of these events occur, particularly in systems with two or more distinctly different toners.

To resolve this problem, such that cleaning of toner particles can occur at both detoning roll nips no matter what polarity the toner particles have when they enter the nips, the present invention basically requires that the toner particles have sufficient charge of either polarity to enable removal by electrostatic forces. To do this, an alternating current bias is applied to the detoning rolls rather than a direct current. The alternating current might take the form of a sinusoidal or a square wave voltage characteristic, but the square wave voltage characteristic is preferred, as shown in Figure 2. The square wave voltage characteristic is applied to both detoning rolls. For the example shown in Figure 1, the square wave would oscillate between -350 volts and + 50 volts as shown in Figure 2. With the cleaner brush bias set at -200 volts, both polarities would have an opportunity to be electrostatically removed from the brush, to...