Patent ID: 7896337
Filing Date: 2011-03-01
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a resist roller for aligning a printing start position timing with a position of a tip of a recording paper; a paper feed roller for feeding the recording paper to the resist roller; a resist sensor for detecting the tip of the recording paper fed on a upstream side of the resist roller; a resist gear for transmitting a rotating force from a driving motor to the resist roller; an external gear to which a rotating force of the resist gear is transmitted; an internal gear positioned coaxially with the external gear and serving to transmit a rotating force from the external gear to the paper feed roller; a paper feed roller driving gear mated with the internal gear to rotate the paper feed roller; a ratchet positioned coaxially with the internal gear and serving to transmit a rotation of the external gear to the internal gear or to release the transmission of the rotation; a ratchet arm having a first claw engaged with the ratchet to transmit the rotation of the external gear to the internal gear, thereby rotating the paper feed roller, and a second claw engaged with a first dent portion provided on a boss of the paper feed roller driving gear to turn the paper feed roller toward a rotation start position and to remove the first claw from the ratchet, thereby stopping the rotation of the paper feed roller; and a second dent portion provided with the boss of the paper feed roller driving gear, the second claw entering the second dent portion and moving within the second dent portion, thereby stopping the rotation of the paper feed roller when the resist sensor detects the tip of the recording paper before the paper feed roller carries out one rotation.