Patent ID: 8437683

Claim:
A sheet feeding device comprising: a sheet feeding tray on which a sheet bundle including a plurality of sheets is stacked; a first air blowing section which blows air in a perpendicular direction to a sheet conveyance direction against a lateral side of the sheet bundle stacked on the sheet feeding tray; a second air blowing section which blows air against a leading edge of the sheet bundle in a sheet conveyance direction from a downstream side in the sheet conveyance direction, a sheet adsorption conveyance section which adsorbs by air suction and conveys sheets one by one from an uppermost sheet of the sheet bundle; a sheet type information transmission section which transmits a sheet type information of the sheet to be used; a shielding member which is arranged to be capable of opening and closing in a ventilating path of the first air blowing section to open or shield the ventilating path; a shielding state switching section which switches a shielding state of the ventilating path by the shielding member to any one state of opening, partial shielding and overall shielding, wherein in the partial shielding state, less amount of air is allowed to pass than an amount of air in the opening state, and the air is totally shielded in the overall shielding state; a sheet adsorption detecting section which detects that the uppermost sheet in the sheet bundle has been adsorbed, and transmits detection information to the sheet adsorption conveyance section; and a control section which controls the shielding member and the shielding state switching section to operate and switch among the state of opening, partial shielding and overall shielding of the ventilating path, in accordance with the sheet type information from the sheet type information transmission section and the sheet adsorption detecting section; wherein in cases where the sheet adsorption detecting section detects that the sheet is adsorbed by the sheet adsorption conveyance section, the control section controls the movement of the shielding state switching section such that in cases where a size of the sheet is less than a prescribed size, to make the partial shielding of the ventilating path for blowing a small amount of the air; and in cases where the size of the sheet is not less than the prescribed size, to make the overall shielding of the ventilating path for not blowing air.