| 摘要 |
A method and apparatus for end-to-end advancement of sheet media in an automatic document feeder suitable for use with a scanner are disclosed. The method involves driving a drive roller in a forward direction to advance a sheet medium section-by-section at a substantially uniform speed across a scan zone of the scanner. Such driving involves accelerating the sheet medium to reach the uniform speed, maintaining the speed while a section is scanned, decelerating the sheet medium to a stop after the section is scanned and reversing the sheet medium by a predetermined distance to allow it to be subsequently accelerated. To prevent an overlap of sheet media during such back and forth advancement of a sheet medium, a pick roller is prevented from reversing when the drive roller is reversed. When the drive roller is driven in the forward direction, the pick roller is only driven after a predetermined delay.
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