Patent ID: 7293641

Claim:
A belt driving mechanism comprising: a driving roller having first and second opposite ends, a first roller axis passing through the first and second opposite ends and a first middle point between the first and second opposite ends, the driving roller being rotated; a driven roller having third and fourth opposite ends and a second roller axis passing through the third and fourth opposite ends and a second middle point between the third and fourth opposite ends, the second roller axis being placed at a certain angle of torsion to a plane containing the first and second opposite ends and the second middle point; an endless belt wrapped around the driving roller and driven roller to run between the driving roller and the driven roller, the driven roller being rotated by the endless belt in accordance with the rotation of the driving roller; a brake configured to apply a braking force to the driven roller to restrict the rotation of the driven roller while keeping the driving roller rotating to run the endless belt, so that the endless belt is slipped on the driven roller; and a control unit configured to control the braking force.