Patent ID: 8235862

Claim:
A planetary gear device comprising: a 3K type planetary gear mechanism which includes a sun outer gear, a sun inner gear, and a planetary gear, where two of three fundamental axes of a drive axis, a driven axis, and a fixed axis are assigned to one of the sun outer gear and the sun inner gear, the other one fundamental axis is assigned to the other of the sun outer gear and the sun inner gear, and performs speed increase and reduction by rotation transmission, wherein the planetary gear includes at least two first and second gears with different numbers of teeth coaxially and integrally; the one of the sun outer gear and the sun inner gear to which two of the fundamental axes are assigned includes at least two third and fourth gears which mesh with the first and second gears of the planetary gear, respectively, and can rotate relative to each other, the gear ratio of the first gear and the third gear is different from that of the second gear and the fourth gear, the other one of the sun outer gear and the sun inner gear to which one of the fundamental axes is assigned includes coaxially and integrally at least two fifth and sixth gears which mesh with the first and second gears of the planetary gear, respectively, the gear ratio of the first gear and the fifth gear and the gear ratio of the second gear and the sixth gear are equal to each other, the number of teeth of the first gear is different from that of the second gear, the number of teeth of the fifth gear is different from that of the sixth gear, and at least one of the planetary gears meshes with its respective sun outer gear and sun inner gear in a different phase than the other planetary gear with its respective sun outer gear and sun inner gear.