Internal gear ring outputting planetary speed reducer

The invention mainly includes an input gear shaft, 2-8 straight-toothed or helical driven gears, 2-8 offset crankshafts firm-jointed with the driven gears, an annular gear, 1-4 annular plates, a disc support, an output shaft, two end caps and a box. Because of outputting power through a output mechanism made up of the annular gear and the output shaft, the invention has large transmission ratio and high operating efficiency.