Xerox Corporation

Gregory E Bell

Thomas R Beikirch

A system for self-aligning a raster input scanner in the slow scan direction where, at start of scan, a target having a variable density image is scanned first until a preset target image line is obtained and the position of the scan carriage registered; then from the registered position, the platen is scanned through a predetermined number of scan lines; following this, the carriage is reversed and returned the same number of scan lines where the target is again scanned and the target image line obtained compared with the previous target image line to determined if a valid scan cycle has taken place.

Slow scan registration self alignment system for raster input scanners

A scanner with scanning array on a movable carriage, a control for regulating the scanning speed of the carriage, a small buffer between the scanner and a workstation, a buffer capacity sensor for continuously monitoring the residual capacity of the buffer, a motion sensor for actuating the array to scan an image line each time the carriage moves a distance of one scan line, and a controller for regulating scanning speed of the carriage to substantially match the image signal output rate of the array with the image signal input rate of the workstation while maintaining a predetermined level of buffer residual capacity, the controller reducing carriage scanning speed as buffer residual capacity decreases in order to maintain the scanner operating as long as possible in the event workstation demand ceases and minimize carriage acceleration/deacceleration forces on scanner noise, vibration, and image quality.

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Rochester, NY, United States of America

Gregory E Bell