US3665382A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vehicle detection apparatus
Assignee: Marbelite Co Inc
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Filing: 1969-10-30
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Granted: 1972-05-23
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Expires: 1989-10-30
Abstract
Abstract A vehicle detection oscillating circuit includes an inductive sensing loop imbedded in a road, or highway. The output signal amplitude of the oscillating circuit fluctuates when a vehicle is near the sensing loop. A differential amplifier has one input coupled without, and a second with a delay circuit to the output of the oscillator circuit. The differential amplifier is coupled to a relay which is normally energized and becomes de-energized upon the detection of a vehicle near the sensing loop.
Inventors
- 👤 Gregory Siklos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:30
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537; H03K17/9542; H03K17/9545; G; G08; G08G; G08G1/00; G08G1/01; G08G1/042; H03K17/9547
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
323 words
A vehicle detection circuit for use with a subsurface inductive loop comprising; input circuit means having an input terminal and an output terminal and capable of oscillating when its input terminal is coupled to the inductive loop, said input circuit means being adapted to provide first and second output signal amplitudes in response to the absence and presence respectively of a vehicle near said loop, a difference sensing means having first and second input terminals and an output terminal, the first input terminal of said difference sensing means being coupled to said output terminal of said input circuit means, a delay means coupled between the output terminal of said input circuit means and the second input terminal of said difference sensing means, said difference sensing means assuming first and second states in response to said input circuit means assuming said first and second output signal amplitudes respectively, said delay means being for delaying the occurrence of the amplitude change from the output terminal of said input circuit means to the second input terminal of said difference sensing means, output circuit means having an input terminal coupled to said output terminal of said difference sensing means, said output circuit means including signal means for sensing when said difference sensing means has changed state, and feedback means coupled from the output of said difference sensing means to said delay means for establishing said difference sensing means near its first state in the absence of said vehicle, wherein said difference sensing means includes a differential amplifier having a pair of transistors biased with their bases coupled to the respective inputs of said difference sensing means and their emitters coupled to a common point, wherein said difference sensing means further includes a sensing transistor having its emitter and base coupled to the respective collectors of said transistor pair, and means for biasing said sensing transistor so that it changes conduction states when said differential amplifier becomes unbalanced.
Claim 2
Dependent Claim
323 words
A vehicle detection circuit for use with a subsurface inductive loop comprising; input circuit means having an input terminal and an output terminal and capable of oscillating when its input terminal is coupled to the inductive loop, said input circuit means being adapted to provide first and second output signal amplitudes in response to the absence and presence respectively of a vehicle near said loop, a difference sensing means having first and second input terminals and an output terminal, the first input terminal of said difference sensing means being coupled to said output terminal of said input circuit means, a delay means coupled between the output terminal of said input circuit means and the second input terminal of said difference sensing means, said difference sensing means assuming first and second states in response to said input circuit means assuming said first and second output signal amplitudes respectively, said delay means being for delaying the occurrence of the amplitude change from the output terminal of said input circuit means to the second input terminal of said difference sensing means, output circuit means having an input terminal coupled to said output terminal of said difference sensing means, said output circuit means including signal means for sensing when said difference sensing means has changed state, and feedback means coupled from the output of said difference sensing means to said delay means for establishing said difference sensing means near its first state in the absence of said vehicle, wherein said difference sensing means includes a differential amplifier having a pair of transistors biased with their bases coupled to the respective inputs of said difference sensing means and their emitters coupled to a common point, wherein said difference sensing means further includes a sensing transistor having its emitter and base coupled to the respective collectors of said transistor pair, and means for biasing said sensing transistor so that it changes conduction states when said differential amplifier becomes unbalanced.
Claim 3
Dependent Claim
288 words
A vehicle detection circuit for use with a subsurface inductive loop comprising; input circuit means having an input terminal and an output terminal and capable of oscillating when its input terminal is coupled to the inductive loop, said input circuit means being adapted to provide first and second output signal amplitudes in response to the absence and presence respectively of a vehicle near said loop, a difference sensing means having first and second input terminals and an output terminal, the first input terminal of said difference sensing means being coupled to said output terminal of said input circuit means, a delay means coupled between the output terminaL of said input circuit means and the second input terminal of said difference sensing means, said difference sensing means assuming first and second states in response to said input circuit means assuming said first and second output signal amplitudes, respectively, said delay means being for delaying the occurrence of the amplitude change from the output terminal of said input circuit means to the second input terminal of said difference sensing means, output circuit means having an input terminal coupled to said output terminal of said difference sensing means, said output circuit means including signal means for sensing when said difference sensing means has changed state, first feedback means coupled from the output of said different sensing means to said delay means for establishing said different sensing means near its first state in the absence of said vehicle, and a second feedback means, coupled from an output of said output circuit means to said presence switch, and operable when said presence switch is in the short presence mode and a vehicle is near said loop to cause said delay time to decrease.
Claim 4
Dependent Claim
288 words
A vehicle detection circuit for use with a subsurface inductive loop comprising; input circuit means having an input terminal and an output terminal and capable of oscillating when its input terminal is coupled to the inductive loop, said input circuit means being adapted to provide first and second output signal amplitudes in response to the absence and presence respectively of a vehicle near said loop, a difference sensing means having first and second input terminals and an output terminal, the first input terminal of said difference sensing means being coupled to said output terminal of said input circuit means, a delay means coupled between the output terminaL of said input circuit means and the second input terminal of said difference sensing means, said difference sensing means assuming first and second states in response to said input circuit means assuming said first and second output signal amplitudes, respectively, said delay means being for delaying the occurrence of the amplitude change from the output terminal of said input circuit means to the second input terminal of said difference sensing means, output circuit means having an input terminal coupled to said output terminal of said difference sensing means, said output circuit means including signal means for sensing when said difference sensing means has changed state, first feedback means coupled from the output of said different sensing means to said delay means for establishing said different sensing means near its first state in the absence of said vehicle, and a second feedback means, coupled from an output of said output circuit means to said presence switch, and operable when said presence switch is in the short presence mode and a vehicle is near said loop to cause said delay time to decrease.
Claim 5
Dependent Claim
27 words
A vehicle detection circuit as defined in claim 2 wherein said input circuit means includes a rectifying means for clipping one polarity of the oscillator output signal.
Claim 6
Dependent Claim
32 words
A vehicle detection circuit as defined in claim 2 wherein said delay means includes an R-C time constant delay circuit and a plurality of transistors connected in a relatively high impedance configuration.
Claim 7
Dependent Claim
34 words
A vehicle detection circuit as defined in claim 2 wherein said output circuit means includes a relay that is in an energized condition when a vehicle is absent from the vicinity of said loop.
Claim 8
Dependent Claim
27 words
A vehicle detection circuit as defined in claim 2 and further including a presence switch coupled to said delay means for selectively changing the delay time thereof.
Claim 9
Dependent Claim
23 words
A vehicle detection circuit as defined in claim 2 wherein said feedback means includes a diode which is periodically forward and reverse biased.
Claim 10
Dependent Claim
21 words
A vehicle detection circuit as defined in claim 2 wherein said first feedback means operates cyclically to establish the first state.
Claim 11
Dependent Claim
45 words
A vehicle detection circuit as defined in claim 2 wherein said difference sensing means includes a differential amplifier having a pair of transistors biased with their bases coupled to the respective inputs of said difference sensing means and their emitters coupled to a common point.
Claim 12
Dependent Claim
33 words
A vehicle detection circuit as defined in claim 9 wherein said difference sensing means further includes a sensing transistor having its emitter and base coupled to the respective collectors of said transistor pair.
Claim 13
Dependent Claim
29 words
A vehicle detection circuit as defined in claim 10 and including means for biasing said sensing transistor so that it changes conduction state when said differential amplifier becomes unbalanced.
Claim 14
Dependent Claim
280 words
A vehicle detection circuit for use with a subsurface inductive loop comprising: input circuit means having an input terminal and an output terminal and capable of oscillating when its input terminal is coupled to the inductive loop, said input circuit means being adapted to provide first and second output signal amplitudes in response to the absence and presence respectively of a vehicle near said loop, a difference sensing means having first and second input terminals and an output terminal, the first input terminal of said difference sensing means being coupled to said output terminal of said input circuit means, a delay means coupled between the output terminal of said input circuit means and the second input terminal of said difference sensing means, said difference sensing means assuming first and second states in response to said input circuit means assuming said first and second output signal amplitudes, respectively, said delay means being for delaying the occurrence of the amplitude change from the output terminal of said input circUit means to the second input terminal of said difference sensing means, output circuit means having an input terminal coupled to said output terminal of said difference sensing means, said output circuit means including signal means for sensing when said difference sensing means has changed state, a presence switch setable in either the short presence or the long presence mode coupled to said delay means for selectively changing the delay time thereof, and feedback means coupled from the output of said output circuit means to said presence switch, and operable when said presence switch is in the short presence mode and a vehicle is near said loop to cause said delay time to decrease.
Claim 15
Dependent Claim
280 words
A vehicle detection circuit for use with a subsurface inductive loop comprising: input circuit means having an input terminal and an output terminal and capable of oscillating when its input terminal is coupled to the inductive loop, said input circuit means being adapted to provide first and second output signal amplitudes in response to the absence and presence respectively of a vehicle near said loop, a difference sensing means having first and second input terminals and an output terminal, the first input terminal of said difference sensing means being coupled to said output terminal of said input circuit means, a delay means coupled between the output terminal of said input circuit means and the second input terminal of said difference sensing means, said difference sensing means assuming first and second states in response to said input circuit means assuming said first and second output signal amplitudes, respectively, said delay means being for delaying the occurrence of the amplitude change from the output terminal of said input circUit means to the second input terminal of said difference sensing means, output circuit means having an input terminal coupled to said output terminal of said difference sensing means, said output circuit means including signal means for sensing when said difference sensing means has changed state, a presence switch setable in either the short presence or the long presence mode coupled to said delay means for selectively changing the delay time thereof, and feedback means coupled from the output of said output circuit means to said presence switch, and operable when said presence switch is in the short presence mode and a vehicle is near said loop to cause said delay time to decrease.
Claim 16
Dependent Claim
33 words
A vehicle detection circuit as defined in claim 12 wherein said delay means includes at least one transistor, means for biasing the transistor, and storage means coupled to a terminal of the transistor.
Claim 17
Dependent Claim
52 words
A vehicle detection circuit as defined in claim 13 wherein said storage means includes a first capacitor having the moveable contact of the presence switch connected thereto for permitting a rapid discharge of the capacitor when the presence switch is in the short presence position and a vehicle is near the loop.
Claim 18
Dependent Claim
32 words
A vehicle detection circuit as defined in claim 14 comprising a second capacitor that is connected in parallel with the first capacitor when the presence switch is in its long presence position.
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) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |