US3813660A
Expired / Lapsed
US
⏱️ 0.0 years remaining
An rf magneto-resistive magnetic domain detector
Assignee: Verizon Laboratories Inc
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Filing: 1972-12-11
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Granted: 1974-05-28
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Expires: 1992-12-11
Abstract
Abstract A cylindrical magnetic domain detector is formed of a pair of series coupled magneto-resistive elements, one of which is disposed in magnetic coupling relationship with a cylindrical magnetic domain memory position, while the other element serves as a reference magneto-resistive element to cancel out interfering noise signals from a rotating domain driving field. The series coupled magneto-resistive elements are connected in a bridge network which is excited by a high frequency RF signal source through a conveniently located transformer. The transformer is formed of a pair of closely spaced conductors printed on a circuit board on which the cylindrical magnetic domain memories are mounted.
Inventors
- 👤 C Buhrer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:51
CPC Classifications
G; G11; G11C; G11C19/00; G11C19/02; G11C19/08; G11C19/0866; G01; G01R; G01R33/00; G01R33/02; G01R33/06; G01R33/09
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
276 words
A detector of magnetic domains being circulated in a crystal of magnetic oxide between discrete positions determined by an overlay permalloy bar pattern, with the domains being moved under drive action from an in-plane magnetic field rotating at a drive frequency comprising a domain sensing magneto-resistive element located on the crystal in proximity to a discrete magnetic domain position to register a change in resistance caused by the magnetic influence of a domain moved onto said discrete domain position; a reference magneto-resistive element located on the crystal at a place selected to respond in a similar manner to the rotating magnetic field as the domain sensing magneto-resistive element; a normally balanced resistive bridge network having a pair of circuit arms with balance output junctions, with one circuit arm being formed of the domain sensing and reference magnetoresistive elements in series connection; means for exciting the bridge network with an RF signal of a frequency which is substantially greater than the drive frequency of the in-plane rotating magnetic field; and RF detecting means for sensing magneto-resistive unbalances of the bridge network caused by a change in the resistance of said domain sensing magneto-resistive element upon the arrival of a magnetic domain at said discrete poSition; said exciting means including an RF transformer having a primary winding coupled to the RF signal and a secondary winding, said secondary winding being electrically connected across said circuit arms and formed of a planar signal turn conductor located to surround the crystal to contact said circuit arms, and said primary winding being formed of a single turn conductor passed in proximity to the secondary winding conductor to couple RF energy thereto.
Claim 2
Dependent Claim
276 words
A detector of magnetic domains being circulated in a crystal of magnetic oxide between discrete positions determined by an overlay permalloy bar pattern, with the domains being moved under drive action from an in-plane magnetic field rotating at a drive frequency comprising a domain sensing magneto-resistive element located on the crystal in proximity to a discrete magnetic domain position to register a change in resistance caused by the magnetic influence of a domain moved onto said discrete domain position; a reference magneto-resistive element located on the crystal at a place selected to respond in a similar manner to the rotating magnetic field as the domain sensing magneto-resistive element; a normally balanced resistive bridge network having a pair of circuit arms with balance output junctions, with one circuit arm being formed of the domain sensing and reference magnetoresistive elements in series connection; means for exciting the bridge network with an RF signal of a frequency which is substantially greater than the drive frequency of the in-plane rotating magnetic field; and RF detecting means for sensing magneto-resistive unbalances of the bridge network caused by a change in the resistance of said domain sensing magneto-resistive element upon the arrival of a magnetic domain at said discrete poSition; said exciting means including an RF transformer having a primary winding coupled to the RF signal and a secondary winding, said secondary winding being electrically connected across said circuit arms and formed of a planar signal turn conductor located to surround the crystal to contact said circuit arms, and said primary winding being formed of a single turn conductor passed in proximity to the secondary winding conductor to couple RF energy thereto.
Claim 3
Dependent Claim
127 words
The magnetic domain detector as claimed in claim 1 wherein said RF detecting means further includes RF amplifying means including a high pass RF filter having an input coupled to balance output junctions of the bridge network and producing an amplified RF signal representative of the unbalance of the bridge network; a phase sensitive detector controlled by an RF signal related to a bridge network RF excitation signal and responsive to the RF bridge unbalance signal to produce a detected signal representative of the bridge unbalance; means responsive to said detected signal for producing an output signal having a magnitude indicative of a magnetic domain induced unbalance of the bridge network at a predetermined timing segment of the rotational cycle of the in-plane magnetic domain driving field.
Claim 4
Dependent Claim
78 words
The magnetic domain detector as claimed in claim 2 wherein said output signal producing means further includes means responsive to a signal representative of the frequency of the in-plane rotating magnetic field for producing an output pulse corresponding to a predetermined time period of the cycle of the in-plane rotating magnetic field; and means enabled by said output pulse for storing said output signal to register the sensing of a magnetic domain at said domain sensing magneto-resistive element.
Claim 5
Dependent Claim
180 words
In a magnetic domain sensing circuit an isolation transformer for exciting a bridge network used to sense magnetic domains being circulated on a planar platelet of magnetic cylindrical domain sustaining crystal with an in-plane magnetic field rotating at a drive frequency comprising a circuit board sized to support a plurality of platelets for sustaining magnetic domains; each of said platelets being provided with a pair of series connected magneto-resistive elements forming one arm of a bridge network, at least one of said magneto-resistive elements being located in domain sensing relationship with a discrete magnetic domain position; an isolation transformer on said circuit board and formed of a primary conductor winding and a plurality of secondary conductor windings; said secondary conductor windings being each effectively electrically coupled across the series connected magneto-resistive elements of a platelet for electrical excitation of a bridge network; said primary conductor winding being passed in close proximity to, and in RF coupling relationship with, said secondary conductor windings to enable said bridge network to be excited with an RF signal for sensing of a magneto-resistive element.
Claim 6
Dependent Claim
180 words
In a magnetic domain sensing circuit an isolation transformer for exciting a bridge network used to sense magnetic domains being circulated on a planar platelet of magnetic cylindrical domain sustaining crystal with an in-plane magnetic field rotating at a drive frequency comprising a circuit board sized to support a plurality of platelets for sustaining magnetic domains; each of said platelets being provided with a pair of series connected magneto-resistive elements forming one arm of a bridge network, at least one of said magneto-resistive elements being located in domain sensing relationship with a discrete magnetic domain position; an isolation transformer on said circuit board and formed of a primary conductor winding and a plurality of secondary conductor windings; said secondary conductor windings being each effectively electrically coupled across the series connected magneto-resistive elements of a platelet for electrical excitation of a bridge network; said primary conductor winding being passed in close proximity to, and in RF coupling relationship with, said secondary conductor windings to enable said bridge network to be excited with an RF signal for sensing of a magneto-resistive element.
Claim 7
Dependent Claim
57 words
The magnetic domain sensing circuit as claimed in claim 4 wherein said secondary windings extend substantially around the platelets with the coupling between the primary and secondary conductor windings being selected to enable the bridge network to be excited with a signal whose frequency is substantially greater than the drive frequency of the in-plate rotating magnetic field.
Claim 8
Dependent Claim
40 words
The magnetic domain sensing circuit as claimed in claim 5 and further including RF detecting means coupled to said bridge network to produce a signal indicative of the arrival of a magnetic cylindrical domain at said discrete magnetic domain position.
Claim 9
Dependent Claim
46 words
The magnetic domain sensing circuit as claimed in claim 6 wherein said RF detecting means further includes a phase sensitive detector effectively coupled to the output of the bridge network and to an RF signal related to the RF excitation signal applied to said bridge network.
Claim 10
Dependent Claim
40 words
The magnetic domain sensing circuit as claimed in claim 7 and further including a high pass RF filter coupled between the bridge network and the phase sensitive detector to attenuate interference signals from said in-plane rotating magnetic domain drive field.
References Cited (Backward Citations)
US3703712A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |