Capacitive length and angle measuring device

Claim 1

A capacitive, plate-like length measuring device, the measured value sensor of which comprises a stationary component (1, 33) and a component (2, 34) which is displaceable in parallel above the upper surface of said stationary component (1, 33) at a short distance therefrom, and the oppositely arranged surfaces of which are provided with capacitor coatings (5, 6; 7, 8, 9) and where the phase relation of the transmitted signal to the received signal is proportional to the displacement between the stationary component and the displaceable component of the measured value sensor, wherein the capacitor coatings (5, 6) of the stationary component (1, 33) are formed by two rows of T-shaped capacitor coatings which engage in the manner of teeth and which are offset in the longitudinal direction (10) by half a measurement scale period (T), whereas the capacitor coatings (7, 8, 9) on the displaceable component (2, 34) serve partially as transmitting electrodes (7.1, 7.2, 7.3) supplied with a.c. voltage and partially as receiving electrodes (8, 9), of which the capacitor coatings which serve as transmitting electrodes (7.1, 7.2, 7.3) are arranged beside one another with respect to the axis of displacement (14) and the receiving electrodes (8, 9) on both of the oppositely arranged end sides of the transmitting electrodes (7.1, 7.2, 7.3) are capacitor coatings which are arranged at a distance from and in each case transversely to the latter and which extend over all the respective capacitor coatings of the transmitting electrodes (7.1, 7.2, 7.3), where at least two respective transmitting voltages participate in a signal transmission in the event of the displacement of the displaceable component (2, 34) over the stationary component (1, 33) and only the displaceable component (2, 3) is connected to an electronic circuit device, characterised in that the transmitting electrodes (7.1, 7.2, 7.3) of the displaceable component (2, 34) are rectangular capacitor coatings which are arranged symmetrically with respect to the axis of displacement (14), and that the receiving electrodes (8, 9) extend in the direction of displacement in such manner that they do not project beyond the capacitor coatings of the transmitting electrodes (7.1, 7.2 7.3), which are fed in a continuous sequence with three respective sinusoidal a.c. voltages (15.1, 15.2, 15.3) which are of equal amplitude and equal frequency and which are shifted in phase with respect to one another by 120°, in such manner that a rotary field is formed which generates an a.c. voltage across the receiving electrodes (8, 9), which latter are separated from the transmitting electrodes (7.1, 7.2, 7.3) by an earthed screen (13), where at least two complete groups (11) of transmitting electrodes (7.1, 7.2, 7.3) with a total respective phase shift of 360° are arranged one beside another on the displaceable component (2, 34), and that the electrical connection between the individual transmitting electrodes which have an equal phase relation to one another takes place on that surface of the displaceable component (2, 34) which faces away from the capacitor coatings.