Sheet feeding apparatus and image forming apparatus

A sheet feeding apparatus comprising:

• a feed rotary member rotationally driven in a sheet feeding direction;
• a retard rotary member rotationally driven in a direction opposite to the sheet feeding direction with a predetermined torque;
• an elastic member for bringing the retard rotary member into press contact to the feed rotary member;
• a rotary member support portion for rotatably supporting the retard member so as to allow it to come into contact with and be moved away from the feed rotary member;
• an elastic member support portion for supporting the elastic member so as to allow an elastic force of the elastic member to be changed;
• and
• pressure fluctuation restraining means for operating the elastic member support portion in association with the pivotal movement of the rotary member support portion that takes place at the time of drive transmission to the retard rotary member to change the elastic force of the elastic member so as to diminish a change in a contact pressure of the retard rotary member for the feed rotary member.

A sheet feeding apparatus comprising:

• a feed roller rotationally driven in a sheet feeding direction;
• a retard roller to which drive is transmitted through a torque limiter and which is rotationally driven in a direction opposite to the sheet feeding direction with a predetermined torque;
• a roller support member supporting the retard roller and provided to be pivotally movable;
• a spring support member onto which a spring is hooked and which is provided to be pivotally movable;
• and
• a gear train provided between respective pivots of the roller support member and the spring support member and adapted to transmit the pivotal movement of the roller support member to the spring support member,
• wherein a gear ratio of the gear train is set such that a pivotal movement angle of the spring support member is larger than that of the roller support member.

A sheet feeding apparatus comprising:

• a feed rotary member rotationally driven in a sheet feeding direction;
• a retard rotary member in contact with the feed rotary member under a predetermined pressure and rotationally driven in a direction opposite to the sheet feeding direction with a predetermined torque;
• pressure fluctuation restraining means for diminishing a change in a contact pressure of the retard rotary member for the feed rotary member generated at the time of drive transmission to the ,retard rotary member;
• and
• image forming means for forming an image on a sheet separated by the feed rotary member and the retard rotary member.

An image forming apparatus comprising:

• a feed rotary member rotationally driven in a sheet feeding direction;
• a retard rotary member rotationally driven in a direction opposite to the sheet feeding direction with a predetermine torque;
• an elastic member for bringing the retard rotary member into press contact to the feed rotary member;
• a rotary member support portion for supporting the retard member in a pivotally movable manner so as to allow it to come into contact with and be moved away from the feed rotary member;
• an elastic member support portion for supporting the elastic member so as to allow an elastic force of the elastic member to be changed;
• pressure fluctuation restraining means for operating the elastic member support portion in association with the pivotal movement of the rotary member support portion that takes place at the time of drive transmission to the retard rotary member to change the elastic force of the elastic member so as to diminish a change in a contact pressure of the retard rotary member for the feed rotary member;
• and
• image forming means for forming an image on a sheet separated by the feed rotary member and the retard rotary member.

An image forming apparatus comprising:

• a feed roller rotationally driven in a sheet feeding direction;
• a retard roller to which drive is transmitted through a torque limiter and which is rotationally driven in a direction opposite to the sheet feeding direction with a predetermined torque;
• a roller support member supporting the retard roller and provided to be pivotally movable;
• a spring support member onto which a spring is hooked and which is provided pivotally movable;
• a gear train provided between respective pivots of the roller support member and the spring support member and adapted to transmit the pivotal movement of the roller support member to the spring support member;
• and
• image forming means for forming an image on a sheet separated by the feed rotary member and the retard rotary member,
• wherein a gear ratio of the gear train is set such that a pivotal movement angle of the spring support member is larger than that of the roller support member.