Patent ID: 8585040

Claim:
A sheet feeder, comprising: a loading member configured to carry a sheet bundle of a plurality of sheet materials loaded thereon; an attraction separation unit including: an endless belt made of a dielectric material, and configured to electrostatically attract and hold an uppermost sheet material of the sheet bundle loaded on the loading member, a plurality of holding rollers configured to hold the endless belt, and including an upstream holding roller located on the upstream side in the feeding direction of the sheet materials and a downstream holding roller located on the downstream side in the feeding direction of the sheet materials, the upstream holding roller configured to be pivoted around an axis concentric with a shaft of the downstream holding roller in accordance with rotation of the downstream holding roller, and an adjustment device provided to the upstream holding roller, and configured to adjust the range of vertical movement of the upstream holding roller in the height direction, a stopper member configured to regulate an angle of the endless belt with respect to an upper surface of the sheet bundle; and a control device operatively connected to the loading member and configured to control, in accordance with the type of sheet materials to be fed, an operation of lifting and lowering the loading member, to thereby allow the adjustment device to adjust the range of movement of the upstream holding roller in the height direction, wherein the control device controls, in accordance with the type of sheet materials to be fed, the operation of lifting and lowering the loading member, to thereby maintain, a constant separation distance between the upstream holding roller and the upper surface of the sheet bundle loaded on the loading member.