Patent ID: 8328179

Claim:
A transport-object transporting device comprising: a forwardly and reversely rotatable driving motor; a transport roller that transports a transport object on a transport path by rotating in a forward direction; a discharge roller that discharges the transport object from the transport path by rotating in the forward direction and that sends the transport object to the transport roller via an inversion path by rotating in a reverse direction, the discharge roller capable of being set in a nip position and a release position; a nip-release switching mechanism that switches the discharge roller between the nip position and the release position in accordance with a rotational position of a cam driving gear; a cam driving gear train that transmits rotation of the driving motor to the cam driving gear, the cam driving gear train having a first planetary gear that transmits power to the cam driving gear by rotating a rocking arm in a predetermined direction when the driving motor rotates in a first direction, and a second planetary gear that transmits power to the cam driving gear via an intermediate gear by rotating the rocking arm in a direction opposite the predetermined direction when the driving motor rotates in a second direction; and a power-transmission blocking mechanism that blocks the transmission of power at an intermediate point of the cam driving gear train so as to maintain the discharge roller in the release position, wherein the power-transmission blocking mechanism includes an engaged portion provided in the rocking arm, and an engaging portion whose engagement position thereof relative to the engaged portion is changeable by changing a rocking direction of the rocking arm, wherein when the engaging portion is set at a predetermined engagement position relative to the engaged portion, the first planetary gear and the second planetary gear are both kept away from the cam driving gear, wherein the power-transmission blocking mechanism is configured to adjust a period of time in which the discharge roller is maintained in the release position to accommodate various lengths of the transport object wherein the engaging portion is moved in a certain direction around the engaged portion along a movement path by changing the rocking direction of the rocking arm, the movement path being formed around the engaged portion or in the engaged portion, wherein the engaged portion includes a first engagement projection and a second engagement projection that are provided in an extension segment extending from the rocking arm, and wherein a guide path that guides the engaging portion to the predetermined engagement position and a hook portion that engages with the engaging portion having reached the predetermined engagement position so as to stop the rocking arm from rocking are provided between the first engagement projection and the second engagement projection.