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Abstract

A distance measuring system (1) is provided with a capacitive sensor (7a, 7b), designed in the form of a differential capacitor (18), for which the partial capacitors (C1, C2 have capacitances that depend on the position to be determined. The system also includes a processing device (5) for determining the desired distance that contains, for example, a sigma/delta demodulator. The partial capacitors (C1, C2) are triggered periodically with binary signals, wherein the trigger signals from the one partial capacitor (C1) are transmitted with a phase offset to the signals from the other partial capacitor (C2). The processing device (5) determines which trigger signals must be used for the evaluation. Within time windows that are synchronized with the edges of the trigger signals, a switch unit (22) allows the associated receiving signals to pass through to the processing unit (5) and blanks out all other signals. The distance measuring system (1) makes it possible to have a low number of interpolation errors with high resolution and long interpolation periods. The distance measuring system (1) can be expanded by adding two essentially independent, parallel-operating relative measuring systems to form an absolute distance measuring system, which determines the absolute position solely from the current measuring values. A nearly optional enlargement of the measuring range is possible by adding further relative measuring systems.

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