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
• 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.