Abstract: A position encoder is described that generates a signal whose phase varies with a position to be determined. A phase detector determines a first phase measurement of the sensor signal during a first mode and a second phase measurement of said sensor signal during a second mode. The phase detector then differences the first and second phase measurements to obtain a phase difference measurement, which it uses to determine an indication of the position to be sensed. A controller controls a signal generator in order to set a start phase of signals generated in at least one of the first and second modes so that the timings at which said sensor signal crosses a reference level are substantially the same.

Abstract: A position encoder is described that generates a signal whose phase varies with a position to be determined. A phase detector determines a first phase measurement of the sensor signal during a first mode and a second phase measurement of said sensor signal during a second mode. The phase detector then differences the first and second phase measurements to obtain a phase difference measurement, which it uses to determine an indication of the position to be sensed. A controller controls a signal generator in order to set a start phase of signals generated in at least one of the first and second modes so that the timings at which said sensor signal crosses a reference level are substantially the same.

Abstract: A capacitive position sensor has a periodic array of electrodes which form capacitors between pairs of the electrodes. The location of a dielectric inhomogeneity in the vicinity of the sensor is determined by comparison of the relative change in the capacitance of the capacitors. The comparison may be carried out using a capacitive Wheatstone Bridge arrangement. The sensor configuration has the advantage that it is independent of the absolute value of the dielectric constant of the environment in which the sensor is located.