Instrument for measuring lengths or angles

US5534859A · kind A · utility

Inventor

• Hans Meyer · Morges, CH

Key dates

• Filing date: Sep 23, 1994
• Grant date: Jul 9, 1996
• Expiry date: Sep 23, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B7/02
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The capacitance sensor (1) comprises a linear or curvilinear array of electrodes (10) connected to means generating on these electrodes (10) a spatially periodic electric potential pattern shifting by increments along said array. Electrodes (10) are disconnected in turn to act as momentarily receiving electrodes (10R), also according to a spatially periodic pattern, shifting by the same increments. Both patterns shift alternately, i.e. the shifts of one pattern taking place between the shifts of the other. A linear or curvilinear scale (2), with a periodic pattern of electrodes (20) or dielectric or conducting relief, facing the sensor, will thus create a periodic fluctuation of the signal coupled on the momentarily receiving electrodes. The relative position between scale (2) and sensor (1) may then be accurately determined by evaluating the phase, after demodulation, of said signal. As the sensor may be integrated on a semiconductor die and the scale may be very narrow, extreme miniaturization and low cost is given. (FIGS. 1a and 1b)