Patent ID: 7631862

Claim:
A sheet feeding device, comprising: a sheet feeding apparatus including a sheet feeding roller including a first circumferential section of said sheet feeding roller having a first friction coefficient and a second circumferential section of said sheet feeding roller having a second friction coefficient configured to rotate in a direction from the first circumferential section to the second circumferential section; a pressure plate provided apart from the sheet feeding roller and configured to mount thereon a recording sheet stack positioned below said sheet feeding roller, said sheet stack having recording sheets ranging from a maximum number to a minimum number; a cam integrally formed with the sheet feeding roller to cause the pressure plate to move upward, the cam and the first circumferential section being provided to cause a recording sheet to contact the first circumferential section when the maximum number of recording sheets are mounted on the pressure plate and when the minimum number of recording sheets are mounted on the pressure plate; and a support body configured to fix the pressure plate by a first guide shaft and a second guide shaft, wherein the pressure plate comprises: a first plate opening having a first length, configured to receive the first guide shaft; and a second plate opening, having a second length, configured to receive the second guide shaft, the first length being larger than the second length, the first plate opening and second plate opening facing the sheet feeding roller, and the pressure plate is configured to move along the guide shafts in a direction toward or away from the sheet feeding roller, wherein the first circumferential section comprises: a first contact point of said sheet feeding roller for contacting, when the sheet feeding roller is rotated, a leading top edge of the recording sheet stack having the maximum number of recording sheets; and a second contact point of said sheet feeding roller for contacting, when the sheet feeding roller is rotated, a leading top edge of the recording sheet stack having the minimum number of recording sheets and for feeding the recording sheets by contact with said sheet feeding roller below which said recording sheet stack is positioned, wherein a radius of the first circumferential section at the second contact point is equal to a radius of a trailing edge point of the first circumferential section.