US4300183A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for generating alternating magnetic fields to produce harmonic signals from a metallic strip
Assignee: SINAI
•
Filing: 1980-03-27
•
Granted: 1981-11-10
•
Expires: 2000-03-27
Abstract
Abstract A system (10) produces an alternating magnetic field in a detection zone between a pair of doorways (346, 348) to produce harmonic signals from a marker (330) when the marker (330) is activated and located in the detection zone. Each of the doorways (346, 348) is provided with a trapezoidally shaped coil which is in a resonant circuit. The coils in the doorways (346, 348) are driven at periodic time periods with in-phase currents to produce aiding magnetic fields perpendicular to doorways in the detection zone. At alternate time periods the coils in the doorways are driven with out-of-phase signals which produce opposing magnetic fields perpendicular to the doorways (346, 348) and aiding magnetic fields parallel to the planes of the doorways. The magnetic fields thus produced in the detection zone cause the marker (330) when activated to produce harmonic signals despite the orientation of the marker (330) as it passes through the detection zone.
Inventors
- 👤 Robert H. Richardson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:28
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2405; G08B13/2408; G08B13/2465; G08B13/2468; G08B13/2471; G08B13/2474; G08B13/2477; G08B13/2488
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
123 words
Apparatus for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising: a first and a second coil of conductive material, each of said coils configured to have a plurality of essentially linear segments, a first group of said segments having each one thereof oriented at an acute angle relative to horizontal and a second group of said segments each one thereof oriented essentially vertically, said first and said second coils spaced apart to form the detection zone therebetween, means for producing an alternating current in said first coil, and means for producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 2
Dependent Claim
123 words
Apparatus for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising: a first and a second coil of conductive material, each of said coils configured to have a plurality of essentially linear segments, a first group of said segments having each one thereof oriented at an acute angle relative to horizontal and a second group of said segments each one thereof oriented essentially vertically, said first and said second coils spaced apart to form the detection zone therebetween, means for producing an alternating current in said first coil, and means for producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 3
Dependent Claim
23 words
The apparatus recited in claim 1 wherein the segments in said first group are each larger than the segments in said second group.
Claim 4
Dependent Claim
18 words
The apparatus recited in claim 1 wherein each of said coils is in the shape of a trapezoid.
Claim 5
Dependent Claim
44 words
The apparatus recited in claim 1 wherein said second group of segments comprises first and second segments, the lower end of the first segment and the upper end of a second segment in a plane which is parallel to a surface supporting said apparatus.
Claim 6
Dependent Claim
61 words
The apparatus recited in claim 1 wherein said means for producing an alternating current in said first coil comprises: a DC voltage source connected to a center tap of said first coil, a capacitor connected to said first coil to create a resonant circuit, and means for periodically grounding a terminal of said first coil to cause said circuit to resonate.
Claim 7
Dependent Claim
71 words
Apparatus as recited in claim 1 wherein said means for producing an alternating current in said second coil comprises: a DC voltage source connected to a center tap of said second coil, a capacitor connected to said second coil to create a resonant circuit, and means for grounding the terminals of said coil alternately to cause said circuit to resonate alternately in-phase then out-of-phase with the current in said first coil.
Claim 8
Dependent Claim
97 words
Apparatus for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising: a first and a second coil positioned parallel and spaced apart forming the detection zone therebetween, each of said coils trapezoidally shaped and having elongate sections thereof oriented at an acute angle from horizontal and the remaining sections thereof oriented vertically, means for producing an alternating current in said first coil, and means for producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 9
Dependent Claim
97 words
Apparatus for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising: a first and a second coil positioned parallel and spaced apart forming the detection zone therebetween, each of said coils trapezoidally shaped and having elongate sections thereof oriented at an acute angle from horizontal and the remaining sections thereof oriented vertically, means for producing an alternating current in said first coil, and means for producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 10
Dependent Claim
41 words
The apparatus recited in claim 7 wherein the upper end of a first of said vertically oriented sections and the lower end of a second of said vertically oriented sections are in a plane parallel to the surface supporting said coils.
Claim 11
Independent Claim
120 words
A method for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising the steps of: positioning first and second coils in vertical planes and parallel at spaced apart locations to define the detection zone therebetween, each of said coils configured to have a plurality of essentially linear segments, a first group of said segments have each one thereof oriented at an acute angle relative to horizontal and a second group of said segments each one thereof oriented essentially vertically, producing an alternating current in said first coil, and producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 12
Independent Claim
120 words
A method for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising the steps of: positioning first and second coils in vertical planes and parallel at spaced apart locations to define the detection zone therebetween, each of said coils configured to have a plurality of essentially linear segments, a first group of said segments have each one thereof oriented at an acute angle relative to horizontal and a second group of said segments each one thereof oriented essentially vertically, producing an alternating current in said first coil, and producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 13
Independent Claim
92 words
A method for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising the steps of: positioning first and second coils in vertical planes and parallel at spaced apart locations to define the detection zone therebetween, each of said coils being trapezoidally shaped and having a greater horizontal dimension than vertical dimensions, producing an alternating current in said first coil, and producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 14
Independent Claim
92 words
A method for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising the steps of: positioning first and second coils in vertical planes and parallel at spaced apart locations to define the detection zone therebetween, each of said coils being trapezoidally shaped and having a greater horizontal dimension than vertical dimensions, producing an alternating current in said first coil, and producing in said second coil an alternating current which alternates between being in-phase and out-of-phase with the current in said first coil.
Claim 15
Independent Claim
126 words
A method for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising the steps of: positioning first and second coils vertically and spaced apart to define the detection zone therebetween, said coils having elongate segments thereof oriented at an acute angle relative to horizontal, driving in-phase alternating currents through said coils to produce aiding horizontal magnetic field from said coils during first periodic time periods, said aiding horizontal magnetic fields perpendicular to said coils, and driving out-of-phase alternating currents through said coils to produce opposing horizontal magnetic fields perpendicular to said coils and aiding magnetic fields parallel to the plane of said coils during second periodic time periods occurring alternately with said first periodic time periods.
Claim 16
Independent Claim
126 words
A method for generating an alternating magnetic field in a detection zone to produce harmonic signals from a metallic strip therein, comprising the steps of: positioning first and second coils vertically and spaced apart to define the detection zone therebetween, said coils having elongate segments thereof oriented at an acute angle relative to horizontal, driving in-phase alternating currents through said coils to produce aiding horizontal magnetic field from said coils during first periodic time periods, said aiding horizontal magnetic fields perpendicular to said coils, and driving out-of-phase alternating currents through said coils to produce opposing horizontal magnetic fields perpendicular to said coils and aiding magnetic fields parallel to the plane of said coils during second periodic time periods occurring alternately with said first periodic time periods.
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) | 1984-11-09 | 1985-05-11 | 1985-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-09 | 1989-05-11 | 1989-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-09 | 1993-05-11 | 1993-11-10 | $7700.00 | Window Closed / Lapsed |