Sheet feeding apparatus and image forming apparatus

Abstract

A sheet feeding apparatus including: a separation claw for restraining both end portions of leading edges of sheets in a width direction orthogonal to a sheet feeding direction, the sheets having reached a sheet feeding position, and separating, one by one, the sheets fed by a pickup roller; and a photosensor detecting that the separation claw has reached a separation position for separating the sheets when a sheet stacking board is raised to detect that the sheets have reached the sheet feeding position, in which the separation claw, which is movable in an up-and-down direction, is moved to the separation position, the photosensor detects that the sheets supported by the sheet stacking board have reached the sheet feeding position of being feedable by the pickup roller, by rise of the sheet stacking board.

1 . A sheet feeding apparatus configured to feed sheets, comprising:
 a rising and lowering sheet supporting portion configured to support the sheets;   a raising and lowering mechanism configured to raise and lower the sheet supporting portion;   a feed roller configured to feed out an uppermost sheet of the sheets supported by the sheet supporting portion;   a detecting portion configured to detect the uppermost sheet of the sheets supported by the sheet supporting portion;   a separation claw, which is movable up and down and configured to separate, one by one, the sheets fed by the feed roller, by restraining a side end of leading edges of the sheets in a width direction orthogonal to a sheet feeding direction; and   a control portion configured to control the raising and lowering mechanism based on a detection by the detecting portion,   wherein the detecting portion is arranged to detect a position of the separation claw, and   the control portion controls the raising and lowering mechanism based on the detection by the detecting portion so that the uppermost sheet of the sheets supported by the sheet supporting portion is located at a position of being feedable by the feed roller.   
     
     
         2 . A sheet feeding apparatus according to  claim 1 , further comprising an air blowing portion configured to blow air to trailing edges of the sheets supported by the sheet supporting portion,
 wherein leading edge portions of the sheets in which the air is blown to the trailing edges by the air blowing portion are held down by the separation claw.   
     
     
         3 . A sheet feeding apparatus according to  claim 1 , further comprising a pair of regulating members configured to regulate positions of the sheets in the width direction, the sheets being supported by the sheet supporting portion,
 wherein the separation claw is provided on each of the pair of regulating members so as to move in an up-and-down direction.   
     
     
         4 . A sheet feeding apparatus according to  claim 3 , wherein the detecting portion is provided on each of the pair of regulating members,
 the raising and lowering mechanism comprises two raising and lowering mechanisms, which support, raise and lower both ends of the sheet supporting portion in the width direction, respectively, and   when raising the sheet supporting portion, the control portion stops drive of each of the two raising and lowering mechanisms in response to detection of the separation claw by the detecting portion provided on each of the pair of regulating members.   
     
     
         5 . An image forming apparatus comprising a sheet feeding apparatus configured to feed sheets and an image forming portion configured to form an image on each of the sheets fed by the sheet feeding apparatus, the image forming apparatus comprising:
 a rising and lowering sheet supporting portion configured to support the sheets;   a raising and lowering mechanism configured to raise and lower the sheet supporting portion;   a feed roller configured to feed out an uppermost sheet of the sheets supported by the sheet supporting portion;   a detecting portion configured to detect the uppermost sheet of the sheets supported by the sheet supporting portion;   a separation claw, which is movable up and down and configured to separate, one by one, the sheets fed by the feed roller, by restraining a side end portion of leading edges of the sheets in a width direction orthogonal to a sheet feeding direction; and   a control portion configured to control the raising and lowering mechanism based on a detection by the detecting portion,   wherein the detecting portion is arranged to detect a position of the separation claw, and   the control portion controls the raising and lowering mechanism based on the detection by the detecting portion so that the uppermost sheet of the sheets supported by the sheet supporting portion is located at a position of being feedable by the feed roller.   
     
     
         6 . An image forming apparatus according to  claim 5 , further comprising an air blowing portion configured to blow air to trailing edges of the sheets supported by the sheet supporting portion,
 wherein leading edge portions of the sheets in which the air is blown to the trailing edges by the air blowing portion are held down by the separation claw.   
     
     
         7 . An image forming apparatus according to  claim 5 , further comprising a pair of regulating members configured to regulate positions of the sheets in the width direction, the sheets being supported by the sheet supporting portion,
 wherein the separation claw is provided on each of the pair of regulating members so as to move in an up-and-down direction.   
     
     
         8 . An image forming apparatus according to  claim 7 , wherein the detecting portion is provided on each of the pair of regulating members,
 the raising and lowering mechanism comprises two raising and lowering mechanisms, which support, raise and lower both ends of the sheet supporting portion in the width direction, respectively, and   when raising the sheet supporting portion, the control portion stops drive of each of the two raising and lowering mechanisms in response to detection of the separation claw by the detecting portion provided on each of the pair of regulating members.