Patent ID: 7575231
Filing Date: 2009-08-18
Classification: B65H

Abstract:
1. A sheet feeding apparatus for feeding sheets, comprising: a sheet tray having a stacking surface on which sheets are stacked; a fan which blows air against the sheets so as to float up a sheet stacked on said sheet tray; a sheet feeder which feeds the sheet floated up by said fan; a position detecting unit configured to detect a position of the sheet which is being floated up by said fan; and a tray lifting and lowering mechanism which lifts and lowers said sheet tray on the basis of a result of detection by said position detecting unit, wherein when it is detected by said position detecting unit that the floated-up sheet is outside a predetermined range, said tray lifting and lowering mechanism lifts or lowers said sheet tray so that the floated-up position of the sheet is within said predetermined range, and when it is detected by said position detecting unit that the floated-up sheet is within said predetermined range, said tray lifting and lowering mechanism neither lifts nor lowers said sheet tray, and wherein when it is detected by said position detecting unit that the floated-up sheet is outside said predetermined range, said position detecting unit detects again a position of the floated-up sheet after a first time period has passed, and when it is detected by said position detecting unit that the floated-up sheet is within said predetermined range, said position detecting unit detects again a position of the floated-up sheet after a second time period shorter than said first time period has passed.