Fife Corporation

Peter Kespohl

The present invention relates to a device for the contactless detection of the position of a moving webs. The web has on one side of the web a detector electrode covering its entire width and on the other side in the area of the web edges transmission electrodes fed by an oscillator in phase opposition, so that the capacitive couplings between the transmission electrodes and the detector electrode respond in opposing fashion to deviations of the web from the central position. The signal received by the detector electrode is processed by a current to voltage converter with a very small input impedance so that the potential of the detector electrode remains at zero, and virtually no capacitive displacement currents flow to a screening electrode In this way, the sensitivity of the measurement array is independent of the web width.

Device for contactless detection of the position of a moving web

A sensor device for a noncontact sensor for the control of moving strips of conductive material. One or more detector electrodes are capacitively coupled to a counterelement. An oscillator governs this coupling and forms two coupling fields at the two edges of the strip. Lateral movement of the strip interacts with the two coupling fields. The at least one detector electrode is embraced by at least one shielding electrode, the shielding electrode being coupled through an amplifier of unity gain factor in such a manner to the at least one detector electrode that the potential of the at least one shielding electrode follows the potential of the detector electrode.

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Konigstein, Germany

Peter Kespohl