Abstract: A capacitive sensor includes a plurality of individual condenser elements, each of which consist of a first, preferably circular, electrode and a second, preferably surrounding ring-shaped, electrode, which are mounted on one side of a nonconducting support. A common conductor is connected to each of the first electrodes of condenser elements. A signal can be detected separately from each of the condenser elements via conductors connected separately to the individual second electrodes. To increase the sensitivity and to avoid interference, the remote side of the support opposite to the one side is provided with a third additional electrode, which is at ground potential and also acts as a shield for interfering couplings. The sensor is used for measurement of the fuel film thickness in the intake of an internal combustion engine.

Abstract: A method for optoelectronically measuring distances and/or angles is suggested. A first and second beam (13, 14 and 61, 63) are directed onto the surface 12 of an object 10 to be measured at pregiven angles (.alpha. and (.beta.) which are diffracted at a common point of incidence on the surface 12. In one embodiment, the two beams (13, 14 and 61, 63) have different frequencies. In another embodiment, the frequency of the two beams (13, 14 and 61, 63) changes simultaneously and one of the two beams (13, 61; 14, 63) has a phase modulation. The phase change of the signal supplied by the sensor 18 is evaluated with reference to a reference signal.

Abstract: A capacitive position sensor includes a capacitor arrangement assembled of a stator (5) and a rotor (6). The stator supports at least three coplanar electrodes (21, 22, 23) having the shape of circle sectors 120.degree.. The rotor supports at least a counterelectrode (25) having the shape of a circle sector of 240.degree.. An oscillator (30) applies two a.c. voltage (u1, u2) of equal amplitude and opposite phase to two of the stator electrode (21, 22). The range of rotation of the rotor is such that the remaining third electrode on the stator is always overlapped by the counterelectrode. Voltage induced on the counterelectrode by means of the a.c. voltages on the stator electrodes is inverted and fed back as a neutralizing voltage (uR) to the third stator electrode (23) until the induced voltage on the counterelectrode reaches zero value. The neutralizing voltage is rectified and integrated into a d.c. voltage (UA) which serves as a measure of the angular position of the rotor (6).