Apparatus for visually and remotely determining an angular position of a relative rotation of parts

Abstract

A visually and remotely readable apparatus is provided which comprises a plurality of sensing units, a control unit and a flexible printed cable (FPC) to connect two units for exchanging information therebetween. A preferable structure of the sensing unit includes a fixed part secured to the body of the apparatus and two oppositely positioned rotatable parts, where two rotatable parts mounted on a common shaft with the fixed part arranged therebetween forming two angular position sensors. Each sensor is based on the capacitive coupling between two working surfaces of the rotatable part and the respective working surfaces of the fixed part with the electrodes are secured thereto. Two working surfaces of one part are confronted with two respective working surfaces of another part forming two working surface pair. Each sensor has two working surface pairs, one working surface pair is sensing pair for sensing angular position; another is coupling pair for coupling sensing signals. A plurality of transmitting electrodes are secured to the working surface of the sensing pair of the fixed part; a receiving electrode is secured to the working surface of the sensing pair of the rotatable part; an output electrodes is secured to the working surface of the coupling pair of the fixed part; a coupling electrode connected to the receiving electrode is secured to the working surface of the coupling pair of the rotatable part. To each of the plurality of the transmitting electrodes is applied a respective one of polyphase squarewave voltages. The capacitive coupling between the electrodes of the sensing pair is dependent on the relative positions of two rotatable part, and the output signal voltages on the output electrode which coupled from the coupling electrode represents the angular position of the rotatable part. In the first embodiment provided for the sensors, the shape of working surfaces is in a conical frustum; the second embodiment, the shape of working surfaces is a cylinder; the third embodiment, the shape of working surfaces is a disc; the fourth embodiment, with a cylinder-shaped working surface and a disk-shaped working surface, is a combination of the second and the third embodiments provided as an example of the application of the embodiments. A circuit of the control unit is provided for processing data, generating control signals for the sensors. By using radio frequency identification (RFID) technique to exchange information with the reader station outside of the apparatus and power the system are also disclosed in the invention.