Patent ID: 7839053

Claim:
A one-way rotational transfer mechanism comprising: a rotary input member rotatable about an axis; a holding member including an axially orthogonal surface lying on a plane orthogonal to said axis; a hollow-cylindrical rotary output shaft positioned coaxially around said rotary input member to be rotatable relative to said rotary input member, and including a cylindrical inner peripheral surface centered on said axis; a circumferential guide groove which is formed in an arc shape with a predetermined curvature in cross section on a portion of said rotary input member which faces said axially orthogonal surface of said holding member so as to surround said axis as viewed in a direction of said axis; and a torque transfer ball, identical in curvature to said circumferential guide groove, and installed in between said axially orthogonal surface, said cylindrical inner peripheral surface and said circumferential guide groove, so as to roll on said axially orthogonal surface and to be continuously held between said axially orthogonal surface and said circumferential guide groove, wherein said circumferential guide groove is shaped to make said torque transfer ball revolve around said rotary input member in a same rotational direction as said rotary input member while trailing behind rotation of said rotary input member and to make said torque transfer ball press against said cylindrical inner peripheral surface when said rotary input member is rotated.