Twin-capacitive shaft angle encoder with analog output signal
US4040041A · kind A · utility
Inventors
Key dates
| Filing date | Oct 24, 1975 |
| Grant date | Aug 2, 1977 |
| Priority date | — |
| Expiry date | Oct 24, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/2412
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A precision capacitive shaft encoder providing a d-c signal corresponding to the angular position of a shaft. Two variable capacitances are coupled in tandem by a rotatable shaft. Each capacitor has a capacitance that varies linearly with a change in the angular position of the shaft, and the sum of the two capacitances is always constant for any angular position of the shaft. Each capacitance is alternately coupled to a reference d-c voltage and a discharge circuit. The capacitances are electrically coupled in series and the charge periodically acquired at the junction of the capacitances is a function of the position of the shaft. An error-compensating voltage is imposed on the junction when the capacitances are coupled to the reference voltages, and the junction is coupled to sample-and-hold apparatus provided with a error-correcting circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.