Patent ID: 8164350

Claim:
Capacitive angular encoder for detecting a rotational position of a rotationally movable object relative to a stationary object, the angular encoder comprising: a stator which is connected to the stationary object, wherein the stator carries at least one first transmitting electrode for generating a first electrostatic field, and at least one first receiving electrode for receiving the first electrostatic field, and wherein the stator carries at least one second transmitting electrode for generating a second electrostatic field, and at least one second receiving electrode for receiving the electrostatic field; a rotor configured for connection to the rotationally movable object and carrying at least one incremental coupling electrode for modulating the first electrostatic field by a change in capacitance in response to a change of a rotational position of the rotor, wherein the rotor carries at least one absolute-value coupling electrode for modulating the second electrostatic field by a change in capacitance in response to an absolute rotational position of the rotor; and, a signal processing circuit for detecting the first and second modulated electrostatic fields, and for determining a measured value for the position of the rotationally movable object in response to the detected fields, wherein at least one of the first and second transmitting electrodes and at least one of the first and second receiving electrodes are arranged on the stator as a plurality of circumferential equidistant interdigital electrodes.