Patent ID: 7913993

Claim:
A sheet feeding device comprising: (a) a sheet stacking table that rises and falls in a sheet stacking direction, on which a plurality of sheets are stacked; (b) a sucking and conveying mechanism having a suction surface, which sucks the sheets stacked on the sheet stacking table from an upper surface of the sheets, sucks an uppermost sheet to be sucked on the suction surface, and conveys the uppermost sheet sucked on the suction surface onto a sheet conveyance path; (c) a floating air blowing mechanism which blows floating air against the sheets from a side surface of the stacked sheets when the sheet is fed from the sheet stacking table; (d) a sheet position detecting sensor which detects an upper surface position in a vertical direction of the sheets stacked, and detects a floating state of the sheets floated by the floating air; and (e) a controller which judges the floating state of the sheets detected by the sheet position detection sensor in a predetermined finite floating state detecting period in connection with a blowing of the floating air, and controls an air volume of floating air blown from the floating air blowing mechanism based on the floating state of the sheets; wherein the sheet position detecting sensor detects the floating state of the sheets based on a number of turning on-and-off operations thereof in the predetermined finite floating state detecting period; wherein there is at least one off and one on operation thereof in the predetermined finite floating state detecting period.