Browse Prior Art Database

SCANNER ASYNCHRONOUS STOP/START OPERATION

IP.com Disclosure Number: IPCOM000026907D
Original Publication Date: 1994-Apr-30
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 106K

Publishing Venue

Xerox Disclosure Journal

Abstract

Proposed is a method to reduce motion quality errors during a start and stop scan sequence on a Constant Velocity Transport (CVT) scanner. The CVT is interfaced with a Personal Computer (PC) which is unable to collect video data at the same rate generated by the CVT scanner. Consequently, each time the scanner stops there is a motion quality error that translates into an image quality error. The error may be caused by any one of several factors that include, for example, paper slippage, roller compression, belt compression, belt stretching, and drive motor steps that are not synchronized to scan lines. When the scanner issues a stop command and stops collecting data, a sheet of paper moving through the CVT may not have stopped. Hence, the physical location of the paper may not line up with the last scan line of video data captured by the scanner. The opposite is true on start up, such that when the scanner issues a start command and begins to collect video data, the paper may not physically move right away or at the proper velocity. Even if the paper were to start and stop instantaneously upon the issuance of the respective start and stop commands, an error is still introduced as a result of the drive motor steps being synchronized to scan line steps. Therefore, in order to reduce these effects, it is proposed that the CVT scanner issue a stop command at a predetermined time, which is based upon the distance a sheet of paper travels, before it stops collecting video data. Accordingly, it is further proposed that the CVT scanner also issue a predetermined start command. The accuracy of issuing start and stop commands is obtained by counting motor tachometer pulses, whereupon there are approximately 10.5 tachometer pulses per scan line. Hence, the positional accuracy of the CVT is improved by a factor of 10.5.

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XEROX DISCLOSURE JOURNAL

SCANNER ASYNCHRONOUS Proposed Classification STOP/START OPERATION U.S. C1.358/288 Donald J. Gusmano
Michael R. Boyack
Nancy R. Kelly
Rudy A. Rodrigues

Int, C1. H04h 01/17

Proposed is a method to reduce motion quality errors during a start and stop scan sequence on a Constant Velocity Transport (CVT) scanner. The CVT is interfaced with a Personal Computer (PC) which is unable to collect video data at the same rate generated by the CVT scanner. Consequently, each time the scanner stops there is a motion quality error that translates into an image quality error. The error may be caused by any one of several factors that include, for example, paper slippage, roller compression, belt compression, belt stretching, and drive motor steps that are not synchronized to scan lines. When the scanner issues a stop command and stops collecting data, a sheet of paper moving through the CVT may not have stopped. Hence, the physical location of the paper may not line up with the last scan line of video data captured by the scanner. The opposite is true on start up, such that when the scanner issues a start command and begins to collect video data, the paper may not physically move right away or at the proper velocity. Even if the paper were to start and stop instantaneously upon the issuance of the respective start and stop commands, an error is still introduced as a result of the drive motor steps being synchronized to scan line steps. Therefore, in order to reduce these effects, it is proposed that the CVT scanner issue a stop command at a predetermined time, which is based upon the distance a sheet of paper travels, before it stops collecting video...