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Drum Seal Location Using Intelligent Electrostatic Probe

IP.com Disclosure Number: IPCOM000045768D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Brewster, JR: AUTHOR [+3]

Abstract

This article describes an apparatus and method for accurately locating a drum seal in an electrophotographic machine.

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Drum Seal Location Using Intelligent Electrostatic Probe

This article describes an apparatus and method for accurately locating a drum seal in an electrophotographic machine.

Electrostatic probe devices are used on electrophotographic machines to sense changes in photoconductor charge level in order to secure consistent copy quality. To accurately sense charge levels, the probe must be calibrated before use. This can be accomplished in machines which contain a drum seal by sensing the charge level on the grounded drum seal as it passes under the probe. A problem occurs, however, in machines which contain a narrow drum seal, in that accurate calibration requires a measurement at the instant that the centerline of the drum seal is aligned with the centerline of the probe.

The figure shows a crystal-controlled microcomputer chip 10 to accurately measure the time differential between a machine sync signal and alignment of the centerlines of probe 11 and seal 12. The machine sync signal is produced when seal 12 passes under sensor 13.

In operation, the photoconductor 14 is charged to its usual potential by a charge-generating corona (not shown), and the illumination mechanism (not shown) is kept off. Microcomputer 10 starts a timer when the edge of the sync signal is sensed by sensor 13 and then falsely calibrates the probe 11 which is sensing the potential of the fully charged photoconductor. This is performed with the probe power supply 15 set to a selected level, f...