US3839700A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Traffic sensor
Assignee: Unisys Corp
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Filing: 1973-02-13
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Granted: 1974-10-01
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Expires: 1993-02-13
Abstract
Abstract A passive magnetic sensor placed in the pavement of a road way includes a symmetric soft iron magnetic circuit configuration having a centrally located pick off solenoid; the ends of the soft iron magnetic circuit are supplied with permanent magnet plates of high magnetic coercivity material for establishing a high reluctance magnetic field path above the pavement. Passage of a vehicle through the path over the sensor results in a Faraday law yield of power to excite an oscillator whose transient radio frequency output is then radiated to actuate remotely located utilization equipment.
Inventors
- 👤 Lorenzo J De
- 👤 G Ross
- 👤 H Durling
- 👤 N Rolfe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:12
CPC Classifications
G; G08; G08G; G08G1/00; G08G1/01; G08G1/042
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
136 words
Sensor means adapted to detect passage of a ferromagnetic object along a surface of a passage way comprising: first and second spaced substantially planar polarized magnet means having opposed major surfaces adapted to be placed substantially parallel to said passage way surface, said first and second spaced substantially planar magnet means being magnetically polarized in opposite senses with poles at said respective opposed major surfaces, first and second spaced substantially planar magnetic circuit means respectively affixed one each to a major surface of said first and second spaced substantially planar polarized magnet means, elongate magnetic core means for magnetically coupling said first and second spaced substantially planar magnetic circuit means, and electrical pick off means coupled to said elongate magnetic core means for producing an output upon passage of said ferromagnetic body proximate said sensor means.
Claim 2
Dependent Claim
136 words
Sensor means adapted to detect passage of a ferromagnetic object along a surface of a passage way comprising: first and second spaced substantially planar polarized magnet means having opposed major surfaces adapted to be placed substantially parallel to said passage way surface, said first and second spaced substantially planar magnet means being magnetically polarized in opposite senses with poles at said respective opposed major surfaces, first and second spaced substantially planar magnetic circuit means respectively affixed one each to a major surface of said first and second spaced substantially planar polarized magnet means, elongate magnetic core means for magnetically coupling said first and second spaced substantially planar magnetic circuit means, and electrical pick off means coupled to said elongate magnetic core means for producing an output upon passage of said ferromagnetic body proximate said sensor means.
Claim 3
Dependent Claim
39 words
Apparatus as described in claim 1 wherein said first and second spaced substantially planar polarized magnet means are constructed of a first material having substantially higher magnetic coercivity than said first and second spaced substantially planar magnetic circuit means.
Claim 4
Dependent Claim
17 words
Apparatus as described in claim 2 wherein said first material is a strontium oxide ferrite magnet material.
Claim 5
Dependent Claim
29 words
Apparatus as described in claim 1 wherein said first and second spaced substantially planar magnetic circuit means lie in a substantially common plane including said elongate magnetic core means.
Claim 6
Dependent Claim
20 words
Apparatus as described in claim 4 wherein said first and second spaced substantially planar magnetic circuit means are substantially rectangular.
Claim 7
Dependent Claim
28 words
Apparatus as described in claim 4 wherein said electrical current pick off means comprises multiple turn solenoidal coil means substantially centrally disposed about said elongate magnetic core means.
Claim 8
Dependent Claim
51 words
Apparatus as described in claim 1 further including radio frequency oscillator means, coupling circuit means responsive to said electrical pick off means for causing oscillations to be generated by said radio frequency oscillator means, antenna means for space radiation of said oscillations, and utilization means responsive to said space radiated oscillations.
Claim 9
Dependent Claim
31 words
Apparatus as described in claim 7 wherein said antenna means comprises loop antenna means lying in a plane substantially parallel to said first and second spaced substantially planar polarized magnet means.
Claim 10
Dependent Claim
31 words
Apparatus as described in claim 1 wherein said first and second spaced substantially planar magnetic circuit means comprises a plurality of laminations with thin dimensions lying parallel to said major surfaces.
Claim 11
Dependent Claim
43 words
Apparatus as described in claim 1 wherein said elongate magnetic core means comprises a plurality of laminations with their thin dimensions lying parallel to said major surfaces and forming a substantial portion of said first and second spaced substantially planar magnetic circuit means.
Claim 12
Dependent Claim
45 words
Apparatus as described in claim 9 wherein a thin lamination lying perpendicular to said plurality of laminations lies in the interface between one portion of said first and second spaced substantially planar polarized magnet means and said first and second spaced planar magnetic circuit means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |