US4339715A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Carrier-domain magnetometers with compensation responsive to variations in operating conditions
Assignee: The General Electric Company PLC
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Filing: 1980-04-23
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Granted: 1982-07-13
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Expires: 2000-04-23
Abstract
Abstract A carrier-domain magnetometer (20) incorporating compensation for changes in its domain rotation frequency/magnetic flux density characteristic due to changes in operating conditions, e.g. electric bias and/or ambient temperature conditions, and/or due to ageing, compensation being obtained by providing means (24 to 28) for monitoring the ratio (F-F o )/F o where F is the domain rotation frequency when both a magnetic field biassing the magnetometer onto the linear part of its frequency/flux characteristic and a magnetic field to be sensed are applied, and F o is the domain rotation frequency when the biassing field only is applied.
Inventors
- 👤 Greville G. Bloodworth
- 👤 Martin H. Manley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:47
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
133 words
A carrier-domain magnetometer provided with magnetic biassing means for subjecting the p-n-p-n structure of the magnetometer to a substantially constant magnetic field directed substantially parallel to the central axis of said structure and having a magnitude such that over a range of operating conditions of the semiconductor device the magnetometer will be biassed for operation on the linear part of its frequency/flux density characteristic, and means for monitoring the value of the ratio (F-F o )/F o or a function thereof, where F represents the frequency of domain rotation when said structure is subjected to the biassing field together with a magnetic field to be sensed, and F o represents the frequency of domain rotation when said structure is subjected to the biassing field in the absence of a field to be sensed.
Claim 2
Dependent Claim
133 words
A carrier-domain magnetometer provided with magnetic biassing means for subjecting the p-n-p-n structure of the magnetometer to a substantially constant magnetic field directed substantially parallel to the central axis of said structure and having a magnitude such that over a range of operating conditions of the semiconductor device the magnetometer will be biassed for operation on the linear part of its frequency/flux density characteristic, and means for monitoring the value of the ratio (F-F o )/F o or a function thereof, where F represents the frequency of domain rotation when said structure is subjected to the biassing field together with a magnetic field to be sensed, and F o represents the frequency of domain rotation when said structure is subjected to the biassing field in the absence of a field to be sensed.
Claim 3
Dependent Claim
15 words
A magnetometer according to claim 1 wherein said magnetic biassing means comprises a permanent magnet.
Claim 4
Dependent Claim
21 words
A magnetometer according to claim 1 wherein said magnetic biassing means comprises an electromagnet energised from a substantially constant current source.
Claim 5
Dependent Claim
82 words
A magnetometer according to claim 1 wherein said monitoring means comprises first means for producing a signal representative of F; second means for deriving from the output of said first means a signal representative of F-F o ; third means for deriving from the output of said first means a signal representative of F o ; and divider means responsive to the outputs of said second and third means for producing a signal representative of the ratio (F-F o )/F o .
Claim 6
Dependent Claim
73 words
A magnetometer according to claim 4 for use where said magnetic field to be sensed is an alternating magnetic field wherein said first means produces an output signal having a unidirectional component representative of F o and an alternating component representative of F-F o ; said second means comprises a high pass filter arranged to reject said unidirectional component and said third means comprises a low-pass filter arranged to reject said alternating component.
Claim 7
Dependent Claim
15 words
A magnetometer according to claim 5 wherein said first means comprises a pulse counter detector.
Claim 8
Dependent Claim
81 words
A magnetometer according to claim 6 wherein said pulse counter detector comprises: a monostable circuit having a period whose reciprocal is greater than the highest value of F which may occur in operation and which is triggered at the frequency F; and a low-pass filter responsive to the output of the monostable circuit and having a cut-off frequency higher than the frequency of the magnetic field to be sensed and below the lowest value of F which may occur in operation.
Claim 9
Dependent Claim
25 words
A magnetometer according to claim 7 wherein the output of said p-n-p-n structure is applied to the monostable circuit via a current to voltage converter.
Claim 10
Dependent Claim
35 words
A magnetometer according to claim 5 including peak detector means responsive to the output of the divider means to produce an output signal representative of the peak value of the magnetic field to be sensed.
Claim 11
Dependent Claim
63 words
A magnetometer according to claim 1 wherein said monitoring means comprises first means for producing a signal representative of F; second means for deriving from the output of the said first means a signal representative of F o ; and divider means responsive to the outputs of said first and second means for producing a signal representative of the ratio F/F o .
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) | 1985-07-12 | 1986-01-11 | 1986-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-07-12 | 1990-01-11 | 1990-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-07-12 | 1994-01-11 | 1994-07-13 | $7700.00 | Window Closed / Lapsed |