Circuit arrangement and method for controlling a displacement measurement sensor

Abstract

A circuit arrangement (1) for controlling an inductive displacement measurement sensor (2) is described. The displacement measurement sensor has a sensor coil (2), which is supplemented by means of a capacitor (Cpar) to form an oscillating circuit. In addition, the circuit arrangement has an oscillator (3) for generating an excitation signal (UExciter), which excites the oscillating circuit to oscillate. The excitation signal (UExciter) is superimposed with a DC voltage (Utemp), the amplitude of which changes when the temperature of the sensor coil (2) changes. The sensor coil (2) is connected to a controllable resistor (Rvar). Furthermore, the circuit arrangement (1) has a comparator (4), which compares the DC voltage (Utemp) with a reference voltage (Utref). On the basis of the result of the comparison, the comparator (4) outputs a control voltage (Ur), which controls the controllable resistor (Rvar). In a further development of the circuit arrangement the control of the controllable resistor (Rvar) is designed in such a way that when the temperature of the sensor coil (2) changes and, as a result, the ohmic resistance (RSensor) of the sensor coil (2) also changes, the total resistance consisting of the sensor coil (RSensor) and the controllable resistor (Rvar) is held essentially constant.

Dependencies are inferred from the claim text.