Patent ID: 7588244

Claim:
A sheet feeder comprising: an air blowing unit floating and separating an upper portion of a sheet of paper laid on a tray; a transfer belt adsorbing and transferring an uppermost sheet of paper laid on the tray; an optical analog sensor sensing an upper face of the uppermost sheet of paper and comprising a sensing face including a light receiving surface; and a shield plate movable with the sheet, the shield plate detecting a position of an upper face of the sheet of paper so as to keep a position of the uppermost sheet at a constant position, an elastic shield member, within and partially parallel with the shield plate, which is in contact with a surface of the shield plate at a side facing toward a light emitting surface of the optical analog sensor, wherein the shield plate comprises: a first surface facing toward the light emitting surface of the optical analog sensor; and a second surface facing toward the light receiving surface of the optical analog sensor, and wherein the elastic shield member comprises: a first end at which the elastic shield member is in contact with the first surface of the shield plate; and a second end at which the elastic shield member is in slide-contact with the light receiving surface of the optical analog sensor.