US3609679A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Earth field vehicle detector
Assignee: THRESHOLD ENGINEERING Inc
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Filing: 1970-01-12
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Granted: 1971-09-28
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Expires: 1990-01-12
Abstract
Abstract A sensing loop is disposed in a fixed position relative to earth, the dimensions of the loop being rather large compared to the length of a vehicle whose movement is to be detected, so that when the vehicle passes over one portion of the loop perimeter in entering the area inside the loop a signal response is produced, and when the vehicle passes over another portion of the perimeter in leaving the loop area another separate response is created. The loop has a low impedance and consists of a small number of conductor turns, typically three or less. For convenience the loop is typically buried beneath the surface of the roadway. Output pulses from the loop are supplied to a signal processing unit, which amplifies and integrates the pulses so as to exclude all frequencies higher than about 10 Hertz, and at the same time provide an output signal whose amplitude is substantially independent of the vehicle''s speed. The processor includes a threshold-responsive trigger circuit which is capable of responding to a signal of sufficient amplitude and of either polarity. An output circuit is actuated by the trigger circuit.
Inventors
- 👤 Robert E Updegraff
- 👤 Robert F D Ausilio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:16
CPC Classifications
G; G08; G08G; G08G1/00; G08G1/01; G08G1/042
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
200 words
Apparatus for detecting the movement of a vehicle on a roadway by interaction between the vehicle and the earth''s magnetic field, comprising: a low-impedance passive sensing loop disposed in a fixed position relative to the earth, the plane of the loop being generally parallel to the roadway surface and the loop width when measured in the direction of vehicle movement being at least comparable to the vehicle length, for producing each time that the vehicle moves over a portion of the perimeter of the loop at least one bipolar output pulse whose polarity is determined by whether the vehicle is entering or leaving the loop and whether or not the vehicle is heavily magnetized; means coupled to said sensing loop for amplifying and integrating said output pulse so as to produce a bipolar output signal whose amplitude is substantially independent of the vehicle speed; threshold-responsive trigger circuit means coupled to said amplifying and integrating means and responsive to said bipolar output signal, when having sufficient amplitude, for producing a trigger signal indicative that the vehicle has closely approached a position above the loop perimeter; and an output circuit coupled to said trigger circuit means and actuated by said trigger signal.
Claim 2
Dependent Claim
200 words
Apparatus for detecting the movement of a vehicle on a roadway by interaction between the vehicle and the earth''s magnetic field, comprising: a low-impedance passive sensing loop disposed in a fixed position relative to the earth, the plane of the loop being generally parallel to the roadway surface and the loop width when measured in the direction of vehicle movement being at least comparable to the vehicle length, for producing each time that the vehicle moves over a portion of the perimeter of the loop at least one bipolar output pulse whose polarity is determined by whether the vehicle is entering or leaving the loop and whether or not the vehicle is heavily magnetized; means coupled to said sensing loop for amplifying and integrating said output pulse so as to produce a bipolar output signal whose amplitude is substantially independent of the vehicle speed; threshold-responsive trigger circuit means coupled to said amplifying and integrating means and responsive to said bipolar output signal, when having sufficient amplitude, for producing a trigger signal indicative that the vehicle has closely approached a position above the loop perimeter; and an output circuit coupled to said trigger circuit means and actuated by said trigger signal.
Claim 3
Dependent Claim
20 words
Apparatus as claimed in claim 1 wherein said trigger circuit is responsive to either polarity of said bipolar output signal.
Claim 4
Dependent Claim
18 words
Apparatus as claimed in claim 1 wherein said sensing loop consists of from one to 10 conductor turns.
Claim 5
Dependent Claim
16 words
Apparatus as claimed in claim 1 wherein said sensing loop consists of a single conductor turn.
Claim 6
Dependent Claim
19 words
Apparatus as claimed in claim 1 wherein the impedance of said loop is of the order of 1 ohm.
Claim 7
Dependent Claim
16 words
Apparatus as claimed in claim 1 wherein said sensing loop is buried beneath the roadway surface.
Claim 8
Dependent Claim
22 words
Apparatus as claimed in claim 1 wherein said sensing loop is supported in a elevated position, and the vehicle passes beneath it.
Claim 9
Dependent Claim
30 words
Apparatus as claimed in claim 1 wherein said sensing loop is arranged in a generally rectangular configuration with two sides thereof being generally perpendicular to the direction of vehicle movement.
Claim 10
Dependent Claim
208 words
Apparatus for detecting the movement of a vehicle on a roadway by interaction between the vehicle and the earth''S magnetic field, comprising: a low-impedance passive sensing loop consisting of from one to 10 conductor turns buried beneath the roadway surface, the plane of the loop being generally parallel to the roadway surface and the loop width when measured in the direction of vehicle movement being at least comparable to the vehicle length, for producing each time that the vehicle moves over a portion of the perimeter of the loop at least one bipolar output pulse whose polarity is determined by whether the vehicle is entering or leaving the loop and whether or not the vehicle is heavily magnetized; means coupled to said sensing loop for amplifying and integrating said output pulse so as to produce a bipolar output signal whose amplitude is substantially independent of the vehicle speed; threshold-responsive trigger circuit means coupled to said amplifying and integrating means and responsive to either polarity portion of said bipolar output signal, when having sufficient amplitude, for producing a trigger signal indicative that the vehicle has closely approached a position above the loop perimeter; and an output circuit coupled to said trigger circuit means and actuated by said trigger signal.
Claim 11
Dependent Claim
208 words
Apparatus for detecting the movement of a vehicle on a roadway by interaction between the vehicle and the earth''S magnetic field, comprising: a low-impedance passive sensing loop consisting of from one to 10 conductor turns buried beneath the roadway surface, the plane of the loop being generally parallel to the roadway surface and the loop width when measured in the direction of vehicle movement being at least comparable to the vehicle length, for producing each time that the vehicle moves over a portion of the perimeter of the loop at least one bipolar output pulse whose polarity is determined by whether the vehicle is entering or leaving the loop and whether or not the vehicle is heavily magnetized; means coupled to said sensing loop for amplifying and integrating said output pulse so as to produce a bipolar output signal whose amplitude is substantially independent of the vehicle speed; threshold-responsive trigger circuit means coupled to said amplifying and integrating means and responsive to either polarity portion of said bipolar output signal, when having sufficient amplitude, for producing a trigger signal indicative that the vehicle has closely approached a position above the loop perimeter; and an output circuit coupled to said trigger circuit means and actuated by said trigger signal.
Claim 12
Dependent Claim
30 words
Apparatus as claimed in claim 9 wherein said sensing loop is arranged in a generally rectangular configuration with two sides thereof being generally perpendicular to the direction of vehicle movement.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |