Automatic document feeder and image forming apparatus including the same

An automatic document feeder comprising:

• an upstream conveyance roller pair disposed upstream relative to an image reading line position of an image reader in a conveyance direction of an original and including an upstream driving roller and an upstream driven roller, the upstream driving roller and the upstream driven roller being in contact in a state in which the original is not conveyed;
• a downstream conveyance roller pair disposed downstream relative to the image reading line position of an image reader in the conveyance direction of an original and including a downstream driving roller and a downstream driven roller, the downstream driving roller and the downstream driven roller being in contact in a state in which the original is not conveyed;
• an upstream auxiliary roller pair including upstream auxiliary rollers disposed coaxially on each shaft of the upstream driving roller and of the upstream driven roller, respectively, each of the upstream auxiliary rollers having a diameter greater than that of the adjacent upstream driving roller and of the adjacent upstream driven roller, respectively, each of the upstream auxiliary rollers being formed of a first elastic member having a lower hardness than a material of the upstream driving roller and a material of the upstream driven roller such that a nip between the upstream driving and driven rollers is in the same position as a nip between the upstream auxiliary roller pair;
• and
• a downstream auxiliary roller pair including downstream auxiliary rollers disposed coaxially on each shaft of the downstream driving roller and of the downstream driven roller, respectively, each of the downstream auxiliary rollers having a diameter greater than that of the adjacent downstream driving roller and of the adjacent downstream driven roller, respectively, each of the downstream auxiliary rollers being formed of a second elastic member having a lower hardness than a material of the downstream driving roller and a material of the downstream driven roller such that a nip between the downstream driving and driven rollers is in the same position as a nip between the downstream auxiliary roller pair.