Browse Prior Art Database

DIGITAL PLATEN POSITIONING CONTROL

IP.com Disclosure Number: IPCOM000024709D
Original Publication Date: 1981-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 64K

Publishing Venue

Xerox Disclosure Journal

Abstract

The optical distance between a photocopier platen and a photoconductor on which latent images of an original are imaged is one variable in determining copy magnification. State of the art photocopiers comprise one or more micro-processors for monitoring and/or controlling photocopier operation and one func-tion the microprocessor can perform is the monitoring and controlling of the optical path length between platen and photoconductor.

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~ XEROX DISCLOSURE JOURNAL

DIGITAL PLATEN POSITIONING CONTROL
L. J. Mason
W. G. Miller
J. M. Moore
J. F. Mrusko

Proposed Classification
U.S. CI. 355/11 Int. CI. G03g 15/00

The optical distance between a photocopier platen and a photoconductor on which latent images of an original are imaged is one variable in determining copy magnification. State of the art photocopiers comprise one or more micro- processors for monitoring and/or controlling photocopier operation and one func- tion the microprocessor can perform is the monitoring and controlling of the optical path length between platen and photoconductor.

According to one photocopier design, the platen is supported in a horizontal plane by a cam mounted to a rotatable shaft. By rotating the cam, the platen is selectively raised and lowered to change the copier magnification. Each cam orientation corresponds to a specific magnification and by properly orienting the cam, a specific magnification results.

The present magnification control includes a shaft encoder which generates pulses for incremental amounts of shaft rotation. A digital representation of the shaft orientation for each desired magnification is stored in microprocessor memory and as a motor rotates the shaft, the encoder output is counted and compared with the count for a particular desired magnification. The motor is driven in an appropriate direction until a match between shaft encoder output and stored encoder position is achieved. As the match i...