Patent ID: 6492787
Filing Date: 2002-12-10
Classification: F16H,G01D,H02K

Abstract:
A speed reducer, comprising:an input shaft for inputting a rotation; a first shaft in co-axial relation with said input shaft; a second shaft in co-axial relation with said first shaft and surrounding one end portion of said first shaft to form a space with said first shaft; a bearing that is interposed between said first shaft and said second shaft, and that maintains the co-axial relation between said first and second shafts while permitting a relative rotation between said first and second shafts; a speed reducing mechanism that reduces the rate of rotation input into said input shaft when one of said first and second shafts is held stationary, and that outputs a reduced rate of rotation to the other of said first and second shafts; and a rotation detector that detects rotational information of the other of said first and second shafts with respect to said one of said first and second shafts, the rotation detector being placed in said space formed between the first shaft and the second shaft, wherein said rotation detector includes: a code plate having positional information corresponding to the rotation; a plurality of detecting portions that detect the positional information of said code plate and that output an electric signal into which said positional information is transformed; and an electronic device having an amplifying system which amplifies a voltage of the electric signal outputted by the plurality of said detecting portions and a removing system by which the influence due to eccentricity of said code plate is removed from the electric signal outputted by the plurality of said detecting portions.