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Automatic document feeder for copiers

  • US 4,750,727 A
  • Filed: 05/28/1987
  • Issued: 06/14/1988
  • Est. Priority Date: 05/28/1987
  • Status: Expired due to Fees
First Claim
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1. In a sheet feeder for a copier for the sequential separation and feeding of individual sheets sequentially from a stack of sheets on a sheet stacking tray by means of an impact type sheet feeder in which the sheet on the top of the stack to be fed is repeatedly impacted by overlying driven flexible frictional flapper blades which engage and flex against the top sheet during impact therewith and feed the top sheet forward away from the stack;

  • the improvement comprising;

    repositioning means for automatically moving, towards or away from one another, one end of said sheet stacking tray with the stack of sheets thereon relative to said impact sheet feeder;

    reference stop means for automatically limiting said movement of said sheet stacking tray towards said impact sheet feeder by said stack repositioning means to an initial stopping position of the top of the stack relative to said impact sheet feeder;

    said reference stop means comprising a fixed mechanical stop positioned to engage the top of the stack and physically prevent the movement of the top of said stack by said repositioning means any closer to said impact sheet feeder than said initial stopping position;

    said stack repositioning means further including automatic reset means for automatically moving the stack in the opposite direction, away from said impact sheet feeder, and out of engagement with said reference stop means, by a small controlled movement distance into an optimum feeding position corresponding to a desired, preset amount of said engagement of said flexible frictional flapper blades against the top sheet of the stack, after said initial stopping position has been set by said reference stop means;

    sheet feeding sensor means for detecting and providing signals as to whether a sheet has been successfully fed from said stack by said impact sheet feeder;

    said stack repositioning means including means for automatically repeating said movement of the stack relative to said impact sheet feeder in response to said signals from said sheet feeding sensor means to reset said optimum feeding position in response to whether or not said impact sheet feeder is feeding sheets from the stack or to compensate for the reduction in the height of the stack as sheets are fed therefrom.

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