This paper describes a capacitive encoder that is characterized by its wireless sensor slider. The main components are made as flexible printed circuit films which thickness is only 0.2 mm. Hence, the sensor can be set up in thin interspaces or on curved surfaces. The sensor consists of a long receiver film and a short transmitter film, respectively containing four-phase and two-phase electrode. The transmitter is used as a slider and the receiver is used as a stator. To realize an un-tethered

more »

... lider, the sensor employs a unique approach; electric power is supplied to the transmitting electrodes by electrostatic induction, thus removing electric wires from the slider. This un-tethered slider can facilitate the sensitive applications where mechanical disturbance caused by an electric wire can be a problem. The principle was verified by a prototype sensor, which showed a linearity error of +/-4 micro meters.