Motion detecting signal source
US4025819A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 19, 1975 |
| Grant date | May 24, 1977 |
| Priority date | — |
| Expiry date | Nov 19, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P3/4802
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for detecting relative movement between two objects which is illustrated in the preferred embodiment as a vehicle road speed signal source including a reed switch oscillator for generating an output signal having a frequency and a magnitude proportional to the road speed of an associated vehicle. Current flows through a biasing coil proximate the reed switch to generate a magnetic field which is slightly less than the field required to close the switch contacts. A permanent magnet means attached to the drive shaft of the vehicle generates a magnetic field which aids the biasing coil magnetic field to close the reed switch contacts. A transistor responds to the closing of the reed switch contacts to turn off the current to the biasing coil which allows the reed switch contacts to open. The transistor responds to turn on the biasing coil current and the cycle is repeated to generate a pulsed signal as long as the magnetic field from the permanent magnet means is present once each revolution of the drive shaft. The oscillator pulsed output signal is shaped into a triangular output signal having one peak for each revolution of the drive shaft.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.