Abstract: The invention concerns an apparatus for digitally measuring the thicknesses of sheets passing between a roller (5) fixed in position and a sensor roller (6) biased toward the fixed roller (5), said apparatus comprising a transducer (2) with at least one input winding, one output winding and with an element (17) sensitive to the position of the sensor roller (6), the transducer input being fed from an oscillator (1). A digital processing unit (4) is connected to the output of the transducer (2) and, on the basis of two measurements, one in the absence of a sheet and the other in the presence of a sheet, issues a digital value of the sheet thickness obtained from the subtraction of the said two measurements.

Abstract: Two relatively movable, spaced elements having electrostatically coupled sets of uniformly spaced interdigitated electrodes form a precision, high gain linear or angular position-measuring transducer. Coupling electrodes on one element capacitively couple to portions of the electrodes on the other element so that electrical connections to external excitation and detection circuitry need be made to only one of the two elements. The shape and dimensions of the electrodes can be arranged to reduce or eliminate undesired impedance variations, capacitive coupling and unwanted harmonic coupling wave frequency components.