Sheet feeding apparatus

A sheet feeding apparatus for separating and feeding sheets one by one, comprising:

• sheet stacking means for supporting sheets;
• a sheet feeding roller, provided at its periphery with a cylindrical surface and a cut-out portion, for feeding out the sheet stacked on said sheet stacking means by means of said cylindrical surface by rotating;
• separation means, capable of abutting against said sheet feeding roller, for separating the sheets one by one between said cylindrical surface of said sheet feeding roller and said separation means;
• an idler sub-roller, disposed in coaxial with said sheet feeding roller, for spacing said sheet feeding roller and said separation means apart from each other when said cut-out portion of said sheet feeding roller is opposed to said separation means;
• biasing means for biasing said separation means toward said sheet feeding roller;
• drive control means for rotating said sheet feeding roller to feed out the sheet and for stopping said sheet feeding roller at a position where said cut-out portion is opposed to said separation means;
• and
• conveying load reducing means for stopping said sheet feeding roller on the way of the sheet feeding by said drive control means, by setting an abutment force for pinching the sheet between said idler sub-roller and said separation means to be smaller than an abutment force for pinching the sheet between said cylindrical surface and said separation means, thereby more reducing a conveying load acting on the sheet when the sheet is pinched between said idler sub-roller and said separation means than when the sheet is pinched between said cylindrical surface and said separation means.

An image forming apparatus for forming an image on a sheet, comprising:

• sheet stacking means for supporting sheets;
• a sheet feeding roller, provided at its periphery with a cylindrical surface and a cut-out portion, for feeding out the sheet stacked on said sheet stacking means by means of said cylindrical surface by rotating;
• separation means, capable of abutting against said sheet feeding roller, for separating the sheets one by one between said cylindrical surface of said sheet feeding roller and said separation means;
• spacing means for spacing apart said sheet feeding roller and said separation means when said cut-out portion of said sheet feeding roller is opposed to said separation means;
• biasing means for biasing said separation means to urge it against said sheet feeding roller or said spacing means;
• conveying load reducing means for reducing a conveying load acting on the sheet being fed, by making an abutment force for pinching the sheet between said spacing means and said separation means smaller than an abutment force for pinching the sheet between said cylindrical surface and said separation means;
• conveying means for conveying the sheet fed out by said sheet feeding roller;
• and
• image forming means for forming an image on the sheet conveyed by said conveying means.

An image forming apparatus for forming an image on a sheet comprising:

• sheet stacking means for supporting sheets;
• a sheet feeding roller, provided at its periphery with a cylindrical surface and a cut-out portion, for feeding out the sheet stacked on said sheet stacking means by means of said cylindrical surface by rotating;
• separation means, capable of abutting against said sheet feeding roller, for separating the sheets one by one between said cylindrical surface of said sheet feeding roller and said separation means;
• an idler sub-roller, disposed in coaxial with said sheet feeding roller, for spacing said sheet feeding roller and said separation means apart from each other when said cut-out portion of said sheet feeding roller is opposed to said separation means;
• biasing means for biasing said separation means toward said sheet feeding roller;
• drive control means for rotating said sheet feeding roller to feed out the sheet and for stopping said sheet feeding roller at a position where said cut-out portion is opposed to said separation means;
• conveying load reducing means for stopping said sheet feeding roller on the way of the sheet feeding by said drive control means, by setting an abutment force for pinching the sheet between said idler sub-roller and said separation means to be smaller than an abutment force for pinching the sheet between said cylindrical surface and said separation means, thereby more reducing a conveying load acting on the sheet when the sheet is pinched between said idler sub-roller and said separation means than when the sheet is pinched between and separated by said cylindrical surface and said separation means;
• conveying means for conveying the sheet fed out by said sheet feeding roller;
• and
• image forming means for forming an image on the sheet conveying by said conveying means.