Low-cost, accurate capacitive encoders

Misgav, Israel —An innovative, noncontact encoder design based on variable capacitance sensing promises to bring industrial-quality performance (up to 18-bit angular resolution or 10 µm or better linear accuracy) to these devices, using low-cost production. All critical parts are made from reinforced polymers.

By Staff May 1, 2001

Misgav, Israel —An innovative, noncontact encoder design based on variable capacitance sensing promises to bring industrial-quality performance (up to 18-bit angular resolution or 10

A rotary encoder consists of a stationary field transmitter, field receiver, processing circuitry, and a dielectric rotor that interacts electrically with the receiver to produce “pure” sine and cosine dc output signals proportional to the rotation angle. (Rotor and transmitter contain conductive patterns on their surfaces.) Since outputs are dc signals rather than pulses, no ac excitation or demodulation is involved. A combination of coarse/fine output determines absolute position over 360°. Reportedly, submicron resolution can be derived from the signals.

Electric Encoder’s benefits include low power consumption, magnetic/RFI immunity, and tolerance to industrial conditions due to its “holistic” rotor design that makes large areas of the rotor active in the sensing at a given time.

www.netzerprecision.com or netzerdesk@aol.com (in the U.S.) Netzer Precision Motion Sensors Ltd. Circle 416


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