Patent ID: 8864325

Claim:
A power transmission device comprising: a driving member configured to be driven on the basis of a command signal from a controller; a lead screw portion configured to be rotationally driven in association with the drive of the driving member; and a power transmitting member configured to move along an axial direction of the lead screw portion in accordance with the rotation of the lead screw portion to transmit the power to a power transmitted member, characterized in that: the controller is configured to control the output of the command signal to the driving member to be stopped so that electric current is not supplied to an exciting coil of the driving member when the power transmitting member is not moved along the axial direction, the power transmitting member includes a pair of projecting portions that each come into point contact with the power transmitted member so as to sandwich the power transmitted member, the power transmitted member rotates about an axis of rotation, the power transmitting member transmits power through the point contact to the power transmitted member to rotate the power transmitted member about the axis of rotation, the power transmitting member is formed with an insertion portion configured to allow insertion of a guide shaft which extends substantially parallel to the lead screw portion, and a movement of the power transmitting member along the axial direction of the lead screw portion causes a holder connected to the guide shaft to rotate about an axis of rotation.