Patent ID: 8499863

Claim:
A friction drive device, comprising: a base frame; a first moveable member and a second moveable member each moveably supported by the base frame; a set of a plurality of first free rollers arranged on the first moveable member along a direction of movement of the first moveable member so as to be individually rotatable around a central axial line thereof; and a set of a plurality of second free rollers arranged on the second moveable member along a direction of movement of the second moveable member so as to be individually rotatable around a central axial line thereof; wherein each first free roller engages a corresponding one of the second free rollers at outer circumferential surfaces thereof with the central axial lines thereof in a non-parallel relationship as at least one of the first and second moveable members move so as to frictionally transmit power from the second free rollers to the first free rollers, characterized by that: an outer peripheral part of each first free roller defining an outer circumferential surface thereof has a different stiffness from that of an outer peripheral part of each second free roller defining an outer circumferential surface thereof.