Patent ID: 7811193

Claim:
A speed reduction device comprising: an eccentrically oscillating speed reducer having: a cylindrical case ( 14 ) in which internal teeth ( 21 ) are formed; a pinion ( 22 ) in which external teeth meshing with the internal teeth are formed; a plurality of crankshafts ( 40 ) which are inserted into the pinion at an eccentric portion ( 44 ) thereof and to which a second external gear ( 58 ) is attached; and a carrier ( 16 ) rotatably supported by the case and supporting rotatably the crankshafts; and a first external gear ( 54 ) rotated by transmission of a driving force from a motor ( 48 ); a large-diameter gear transmitting the rotation of the first external gear; and a small-diameter gear ( 66 ) transmitting the rotation of the large-diameter gear to the second external gear; and a supporting shaft ( 59 , 76 ) which is supported by the carrier and in which the large-diameter gear and the small-diameter gear are provided, wherein the large-diameter gear is larger than the small-diameter gear and the large-diameter gear and the small-diameter gear are coaxial.