Browse Prior Art Database

Pre-Transfer Corona Treatment of Background Toner

IP.com Disclosure Number: IPCOM000103921D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 4 page(s) / 85K

Publishing Venue

IBM

Related People

Mabrouk, SA: AUTHOR [+2]

Abstract

Disclosed is a pre-transfer corona treatment of toner in order to reduce the toner amount that transfers to the copy/print sheet. This treatment is applied mainly to the background areas and not to the image areas. Therefore, it has a minimum effect on the transfer efficiency to image areas. The technique can be applied to both copiers and printers, and provides a process having wide operational latitude.

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Pre-Transfer

Corona

Treatment of Background Toner

      Disclosed is a pre-transfer corona treatment of toner in order
to reduce the toner amount that transfers to the copy/print sheet.
This treatment is applied mainly to the background areas and not to
the image areas.  Therefore, it has a minimum effect on the transfer
efficiency to image areas.  The technique can be applied to both
copiers and printers, and provides a process having wide operational
latitude.

      When excessive background toner is developed on the
photoconductor surface in a copier/printer process, it is possible to
reduce its transfer to the print sheet by changing the toner charge
polarity to the same polarity as the transfer corona/roll.  However,
this improvement in print background is usually associated with a
reduction in print transfer efficiency.  The method described here
improves print background while minimizing the reduction in print
transfer efficiency.

      In the process a Scorotron corona is used as a pre-transfer
treatment with the screen grid potential maintained at the developer
bias or close to it.  This has the effect of directing most of the
corona ions toward the background areas to reduce background toner
transfer, while fewer ions arrive at the image areas.  This maintains
high image transfer efficiency.

      In Fig. 1, where the Photo Conductor (PC) is charged
negatively, the toner polarity is negative, and development occurs in
discharged areas.  T...