Patent ID: 6788220
Filing Date: 2004-09-07
Classification: G01D

Abstract:
A capacitive angle encoder for sensing rotation of a shaft, the encoder comprising:at least one stator, comprising an electrostatic field transmitter, which is adapted to generate an electrostatic field; an electrostatic field receiver, which is adapted to receive the electrostatic field and generate a signal responsive thereto; a rotor, adapted to rotate with the shaft, and having coarse and fine periodic electrically-active patterns thereon, the fine pattern comprising a sinusoidal pattern disposed circumferentially around the shaft, wherein the patterns modulate the electrostatic field responsive to rotation of the shaft by inducing a periodic variation in capacitance between the transmitter and the receiver; and processing circuitry, coupled to the receiver so as to sense the periodic variation in the signal and to determine, responsively to the periodic variation, coarse and fine measures of a rotation angle of the shaft.