Sheet feeding apparatus, image reading device and image forming apparatus

A sheet feeding apparatus comprising:

• a conveying roller pair configured to convey a sheet;
• a discharge roller pair including a driving discharge roller configured to normally rotate and discharge the sheet out of the apparatus and to reversely rotate and convey again the sheet that has been once passed through the conveying roller pair toward the conveying roller pair, and a driven discharge roller configured to rotate by being driven by the driving discharge roller;
• a driving source;
• and
• a separating mechanism configured to contact the driven discharge roller with the driving discharge roller and separate the driven discharge roller from the driving discharge roller by switching input rotations generated by the driving source to normal and reverse rotations, the separating mechanism including:
• a support portion rotatably supporting the driven discharge roller;
• a swing mechanism configured to swing the support portion by receiving a driving force from the driving source and separate the driven discharge roller from the driving discharge roller;
• a planetary gear mechanism provided within a power transmission path from the driving source to the swing mechanism and including first and second rotary components;
• and
• a switching portion switching the planetary gear mechanism to a transmission state in which a power of the driving source is transmitted from the driving source to the swing mechanism and to a cutoff state in which the transmission of the power from the driving source to the swing mechanism is cut off, the switching portion including:
• a first locking portion locking the first rotary component and putting the planetary gear mechanism in the transmission state;
• and
• a second locking portion locking the second rotary component and putting the planetary gear mechanism into the cutoff state;
• a restricting portion configured to restrict a rotation range of a rotary shaft of the swing mechanism to which the driving force from the planetary gear mechanism is transmitted between a first position in which the driven discharge roller is in pressure contact with the driving discharge roller and a second position in which the driven discharge roller is separated from the driving discharge roller;
• and
• a torque limiter interposed between the rotary shaft of the swing mechanism and the planetary gear mechanism and cutting off the transmission of the power from the planetary gear mechanism to the rotary shaft in a case where the rotation of the rotary shaft is restricted by the restricting portion and a driving torque to be transmitted from the planetary gear mechanism to the rotary shaft exceeds a predetermined value.

A sheet feeding apparatus comprising:

• a conveying roller pair configured to convey a sheet;
• a discharge roller pair including a driving discharge roller configured to normally rotate and discharge the sheet out of the apparatus and to reversely rotate and convey again the sheet that has been once passed through the conveying roller pair toward the conveying roller pair, and a driven discharge roller configured to rotate by being driven by the driving discharge roller;
• a driving source;
• and
• a separating mechanism configured to contact the driven discharge roller with the driving discharge roller and separate the driven discharge roller form the driving discharge roller by switching input rotations generated by the driving source to normal and reverse rotations, the separating mechanism including:
• a support portion rotatably supporting the driven discharge roller;
• a swing mechanism configured to swing the support portion by receiving a driving force from the driving source and separate the driven discharge roller from the driving discharge roller;
• a planetary gear mechanism provided within a power transmission path from the driving source to the swing mechanism and including first and second rotary components;
• and
• a switching portion switching the planetary gear mechanism to a transmission state in which a power of the driving source is transmitted from the driving source to the swing mechanism and to a cutoff state in which the transmission of the power from the driving source to the swing mechanism is cut off, the switching portion including:
• a first locking portion locking the first rotary component and putting the planetary gear mechanism in the transmission state;
• and
• a second locking portion locking the second rotary component and putting the planetary gear mechanism into the cutoff state;
• a restricting portion configured to restrict a rotation range of a rotary shaft of the swing mechanism to which the driving force from the planetary gear mechanism is transmitted between a first position in which the driven discharge roller is in pressure contact with the driving discharge roller and a second position in which the driven discharge roller is separated from the driving discharge roller,
• wherein the second rotary component includes a tooth lacking gear transmitting the power by meshing with a driven gear provided on the rotary shaft of the swing mechanism, and the tooth lacking gear includes a gear portion rotating the rotary shaft by a predetermined angle between the first and second positions by meshing with the driven gear and a tooth lacking portion continuously formed with the gear portion and cutting off the transmission for the power to the rotary shaft by un-meshing with the driven gear.