US4463314A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Earth field compensation for a magnetic detector by imparting a permanent magnetization to a magnetic material contiguous the detector
Assignee: Northrop Grumman Corp
•
Filing: 1980-07-28
•
Granted: 1984-07-31
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Expires: 2000-07-28
Abstract
Abstract A magnetometer compensation scheme wherein a magnetizable material adjacent the magnetometer is given a certain permanent magnetization to cancel the effect of the earth magnetic field at the location of the magnetometer.
Inventors
- 👤 James H. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:14
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/025
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
Magnetic detector compensation apparatus comprising: (A) a magnetic detector for stationary use at a location and being subject to the influence of the earth's magnetic field; (B) a magnetic material contiguous said detector; (C) circuit means for generating an electrical signal to impart a controlled permanent magnetization to said material of a value to substantially cancel the effect of said earth's magnetic field at said detector location and for thereafter removing said electrical signal.
Claim 2
Dependent Claim
74 words
Magnetic detector compensation apparatus comprising: (A) a magnetic detector for stationary use at a location and being subject to the influence of the earth's magnetic field; (B) a magnetic material contiguous said detector; (C) circuit means for generating an electrical signal to impart a controlled permanent magnetization to said material of a value to substantially cancel the effect of said earth's magnetic field at said detector location and for thereafter removing said electrical signal.
Claim 3
Dependent Claim
14 words
Apparatus according to claim 1 wherein: (A) said magnetic material surrounds said magnetic detector.
Claim 4
Dependent Claim
21 words
Apparatus according to claim 2 wherein: (A) said magnetic material is comprised of a plurality of turns of magnetic recording tape.
Claim 5
Dependent Claim
13 words
Apparatus according to claim 1 wherein: (A) said magnetic detector is a magnetometer.
Claim 6
Dependent Claim
14 words
Apparatus according to claim 4 wherein: (A) said magnetometer is a flux gate magnetometer.
Claim 7
Dependent Claim
65 words
Apparatus according to claim 1 wherein said circuit means includes: (A) a magnetizing winding positioned relative to said magnetic material and operable to receive magnetizing current to thereby impart a permanent magnetization to said magnetic material; (B) a DC current source; (C) means for adjusting the value of current supplied by said source; and (D) means for intermittently supplying said current to said magnetizing winding.
Claim 8
Dependent Claim
20 words
Apparatus according to claim 6 which includes: (A) means for reversing the polarity of current supplied to said magnetizing winding.
Claim 9
Dependent Claim
26 words
Apparatus according to claim 7 wherein: (A) said means for reversing is a reversing switch connected in circuit between said current source and said magnetizing winding.
References Cited (Backward Citations)
US2241499A
Cited
US2151627A
Cited
US2715198A
Cited
US2743415A
Cited
US2891216A
Cited
US2938164A
Cited
US3311821A
Cited
US3389333A
Cited
US3441841A
Cited
US3639828A
Cited
US3736502A
Cited
US4058782A
Cited
US3991361A
Cited
US4152745A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-07-31 | 1988-01-30 | 1988-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-31 | 1992-01-30 | 1992-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-31 | 1996-01-30 | 1996-07-31 | $7700.00 | Window Closed / Lapsed |