US3825889A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vehicle detection system
Assignee: CANOGA CONTROLS CORP
•
Filing: 1973-01-08
•
Granted: 1974-07-23
•
Expires: 1993-01-08
Abstract
Abstract A system useful for indicating the entry of a vehicle onto a specified area of the earth''s surface. The system includes a magnetic field sensor which yields an output signal indicative of the magnetic field intensity thereat. The sensor is mounted adjacent to but outside of a volume being monitored which constitutes the projection of the specified area in the direction of the magnetic field thereat. When the magnetically permeable mass of a vehicle enters the volume being monitored, it increases magnetic field intensity therein but reduces the field intensity outside of this volume. The reduction in field intensity is recognized by the sensor which then energizes an indicating device, which in the case of a service station installation, for example, can be a remote bell. The sensor preferably comprises a flux gate magnetometer mounted within a thin substantially rigid housing dimensioned to fit within a slot formed by saw cutting a roadway surface.
Inventors
- 👤 R Koerner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:59
CPC Classifications
G; G08; G08G; G08G1/00; G08G1/01; G08G1/042
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
188 words
A system useful for monitoring vehicular traffic on a roadway surface including four or more lanes, respectively designated as first, second, third . . . . N said system including: M probes, where M is an integer equal to or immediately greater than N/2; means positioning said M probes adjacent to said roadway surface with the first of said M probes substantially coincident with the boundary line between the first and second lanes, the seconf of said M probes substantially coincident with the boundary line between the third and fourth lanes and with subsequent ones of said M probes respectively substantially coincident with alternate boundary lines between adjacent lines; each of said probes including a magnetic field sensing device therein providing an output signal component indicative of the level of magnetic field intensity through a sAmpling area thereof; means providing a reference signal representative of a threshold level of magnetic field intensity; and circuit means responsive to said reference signal and said output signal components for indicating when the level of magnetic field intensity sensed by one of said field sensing devices is reduced below said threshold level.
Claim 2
Independent Claim
188 words
A system useful for monitoring vehicular traffic on a roadway surface including four or more lanes, respectively designated as first, second, third . . . . N said system including: M probes, where M is an integer equal to or immediately greater than N/2; means positioning said M probes adjacent to said roadway surface with the first of said M probes substantially coincident with the boundary line between the first and second lanes, the seconf of said M probes substantially coincident with the boundary line between the third and fourth lanes and with subsequent ones of said M probes respectively substantially coincident with alternate boundary lines between adjacent lines; each of said probes including a magnetic field sensing device therein providing an output signal component indicative of the level of magnetic field intensity through a sAmpling area thereof; means providing a reference signal representative of a threshold level of magnetic field intensity; and circuit means responsive to said reference signal and said output signal components for indicating when the level of magnetic field intensity sensed by one of said field sensing devices is reduced below said threshold level.
Claim 3
Dependent Claim
53 words
The system of claim 1 wherein each of said probes includes a thin substantially solid housing adapted for insertion into a slot, saw cut in the roadway surface across said lanes; and a multiconductor cable, adapted to be received in said slot, interconnecting said probes to one another and to said circuit means.
Claim 4
Dependent Claim
51 words
The system of claim 2 including bias means for producing a magnetic bias field through the said sampling areas of said sensing devices substantially equal in magnitude and opposite in direction to the fields through said sampling areas in the absence of vehicular traffic on said roadway proximate to said probes.
Claim 5
Dependent Claim
115 words
The system of claim 3 wherein said magnetic field sensing devices each comprises a flux gate magnetometer providing an output signal component constituting an AC signal of frequency 2f and phase phi 1 in response to a magnetic field intensity in a first direction through a sampling area and of frequency 2f and phase ( phi 1 + 180*) in response to a magnetic field intensity in an opposite direction through the sampling area; means providing a second reference signal of frequency 2f and phase phi 1; and wherein said circuit means includes means for determining whether the sum of output signal components is in phase or out of phase with said second reference signal.
Claim 6
Dependent Claim
182 words
Apparatus suitable for burial beneath the surface of a roadway for producing an electrical signal indicative of the presence of a vehicle proximate thereto on said roadway surface, said apparatus comprising: magnetometer means for providing an electrical output signal indicative of the level of magnetic field intensity through a sampling area thereof; a substantially rigid housing having a thickness dimension T on the order of one quarter inch and a depth dimension D on the order of two inches whereby said housing can be accomodated in a slot in the roadway surface having a thickness and depth greater than T and D, respectively; said housing enveloping said magnetometer means; means in said housing supporting said magnetometer means with said sampling area thereof oriented to indicate the level of magnetic field intensity extending substantially parallel to said housing depth dimension; and a multiconductor cable having a thickness dimension less than T adapted to be received in said slot, said cable extending into said housing substantially perpendicular to the thickenss dimension T thereof with the conductors of said cable connected to said magnetometer means.
Claim 7
Dependent Claim
182 words
Apparatus suitable for burial beneath the surface of a roadway for producing an electrical signal indicative of the presence of a vehicle proximate thereto on said roadway surface, said apparatus comprising: magnetometer means for providing an electrical output signal indicative of the level of magnetic field intensity through a sampling area thereof; a substantially rigid housing having a thickness dimension T on the order of one quarter inch and a depth dimension D on the order of two inches whereby said housing can be accomodated in a slot in the roadway surface having a thickness and depth greater than T and D, respectively; said housing enveloping said magnetometer means; means in said housing supporting said magnetometer means with said sampling area thereof oriented to indicate the level of magnetic field intensity extending substantially parallel to said housing depth dimension; and a multiconductor cable having a thickness dimension less than T adapted to be received in said slot, said cable extending into said housing substantially perpendicular to the thickenss dimension T thereof with the conductors of said cable connected to said magnetometer means.
References Cited (Backward Citations)
US1992214A
Cited
US3355707A
Cited
US3249915A
Cited
US3458802A
Cited
US3434047A
Cited
US3649958A
Cited
US3714626A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |