Vehicular magnetic coded signalling apparatus
US4185265A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 1977 |
| Grant date | Jan 22, 1980 |
| Priority date | — |
| Expiry date | Jun 9, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08G1/096783
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Coded binary signals are coupled to an automotive vehicle by a magnetic signpost embedded in a traversed roadway lane. The signpost includes polarity coded magnetic pole faces having vertically directed flux lines at differing spaced longitudinal regions along the lane. Pole faces are arranged so a flux null is between adjacent longitudinal regions. Differing signals are coupled to vehicles going in opposite directions in adjacent lanes by unambiguously coding the signpost in opposite directions and arranging the pole faces so that magnetic flux continuously extends across a majority of both lanes. A detector on a vehicle includes a magnetic field concentrator including a pair of vertically extending and aligned low reluctance magnetic pole pieces having an air gap between them, in which a Hall plate is positioned. The pole piece closest to the road has shorter length than the pole piece remote from the roadway. A waveform derived by the detector includes a base line subject to drift due to ambient conditions and a pulse as the transducer crosses each region. To eliminate base line drift, a circuit with a negative feedback loop derives an analog offset signal indicative of base lin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.