Rotary encoder with neutral position
US5491632A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | May 26, 1994 |
| Grant date | Feb 13, 1996 |
| Priority date | — |
| Expiry date | May 26, 2014 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB62D15/0245
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A rotary encoder capable of detecting angular rotation of a rotating shaft, and identifying its neutral position without the need for multiple encoder wheels. A magnetoresistive sensor is positioned adjacent the periphery of a single multipole magnet ring attached to a steering wheel shaft. The magnet ring comprises alternating N-pole and S-pole magnetic regions along its periphery, the surface of one of the regions containing a demagnetized portion. The sensor produces a sinusoidal signal as the shaft is rotated, responsive to the passage of the magnetic regions, with a period equal to the passage of two successive magnetic regions adjacent the sensor. The angular position of the shaft which aligns the demagnetized portion adjacent the sensor corresponds to the shaft's neutral position. Aligning of the demagnetized portion adjacent the sensor causes a voltage irregularity within the sensor's otherwise sinusoidal output signal, which is detected by a signal processing circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.