Magnetic field change detection circuitry having threshold establishing circuitry
US6064199A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1998 |
| Grant date | May 16, 2000 |
| Priority date | — |
| Expiry date | Feb 23, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D18/001
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for detecting a tooth of a body. The tooth has an edge terminating in a notch. The tooth and notch are disposed along an edge of the body. The apparatus includes a pair of Hall effect cells disposed adjacent to, and laterally disposed along, the edge of the body. A magnet is positioned to provide a magnetic field through the edge of the body and Hall effect cells. The magnitude of field passing through the Hall effect cells is related to the relative position between the tooth and Hall effect cells. The Hall effect cells produce an output voltage related to magnitude of magnetic field passing through the cell. A differencing circuit is fed by the pair of Hall effect cell produced voltages for producing a difference signal having a peak when the edge of the tooth is positioned between the pair of Hall effect cells. A peak detector detects the peak produced by the difference signal. A threshold circuit is fed by the differencing signal for producing a gating signal when magnitude of the difference signal exceeds a threshold level. The gating signal enables peak detector produced pulse to pass to an output of the apparatus and inhibits such detected peak from passing to the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.