US 7,575,231 B2
Sheet feeding apparatus, sheet feeding method and control program
Ichiro Sasaki, Toride (Japan); Keizo Isemura, Koganei (Japan); Mitsuhiko Sato, Kashiwa (Japan); Naohisa Nagata, Moriya (Japan); Akinobu Nishikata, Kashiwa (Japan); and Hidenori Sunada, Toride (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Mar. 17, 2005, as Appl. No. 11/81,736.
Claims priority of application No. 2004-083349 (JP), filed on Mar. 22, 2004.
Prior Publication US 2005/0206068 A1, Sep. 22, 2005
Int. Cl. B65H 3/14 (2006.01)
U.S. Cl. 271—98  [271/153; 271/97] 6 Claims
OG exemplary drawing
 
5. An image forming apparatus comprising:
a sheet tray having a stacking surface on which sheets are stacked;
a fan which blows air against the sheets to float up a sheet stacked on said sheet tray;
a sheet feeder which feeds the sheet floated up by said fan;
an image forming unit which forms images on the sheet fed by said sheet feeder;
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.