Patent US5565834A successfully refreshed from Google Patents.
US5565834A
Expired / Lapsed
US
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Magnetic assembly for a nuclear magnetic resonance imaging system
Assignee: Oxford Instruments UK Ltd
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Filing: 1993-03-17
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Granted: 1996-10-15
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Expires: 2013-03-17
Abstract
Abstract A magnet assembly has a generally U-shape, the bight of the U including a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U. The dimensions of the assembly are chosen such that: ##EQU1## where: L g is the length of the gap between the arms, L m is the length of the magnet, B r is the remnant field of the magnet, and B g is the field in the gap.
Inventors
- 👤 Peter Hanley
- 👤 Ian L. McDougall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:14
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/28; G01R33/38; G01R33/383
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
86 words
A magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that: ##EQU8## where: L g is the length of the gap between the arms, L m is the length of the magnet, B r is the remnant field of the magnet, and B g is the field in the gap.
Claim 2
Dependent Claim
86 words
A magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that: ##EQU8## where: L g is the length of the gap between the arms, L m is the length of the magnet, B r is the remnant field of the magnet, and B g is the field in the gap.
Claim 3
Dependent Claim
38 words
An assembly according to claim 1, wherein the permanent magnet generates a magnetic field whose magnetisation direction extends along the bight of the U, circulates through the arms of the U and across the gap between the arms.
Claim 4
Dependent Claim
21 words
An assembly according to claim 2, further comprising one or more cladding magnets which compensate for flux leakage from the assembly.
Claim 5
Dependent Claim
44 words
An assembly according to claim 2, further comprising one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetisation of the correction magnets being substantially parallel with the direction of magnetisation of the permanent magnet of the assembly.
Claim 6
Dependent Claim
21 words
An assembly according to claim 1, further comprising one or more cladding magnets which compensate for flux leakage from the assembly.
Claim 7
Dependent Claim
20 words
An assembly according to claim 5, wherein the cladding magnets are provided on each externally facing surface of the assembly.
Claim 8
Dependent Claim
44 words
An assembly according to claim 5, further comprising one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetisation of the correction magnets being substantially parallel with the direction of magnetisation of the permanent magnet of the assembly.
Claim 9
Dependent Claim
44 words
An assembly according to claim 1, further comprising one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetisation of the correction magnets being substantially parallel with the direction of magnetisation of the permanent magnet of the assembly.
Claim 10
Dependent Claim
89 words
A nuclear magnetic resonance imaging system comprising a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms, and a ferro-magnetic pole piece provided along the face of the permanent magnet and facing towards the working volume, the pole piece provided with a triangular front aspect.
Claim 11
Dependent Claim
89 words
A nuclear magnetic resonance imaging system comprising a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms, and a ferro-magnetic pole piece provided along the face of the permanent magnet and facing towards the working volume, the pole piece provided with a triangular front aspect.
Claim 12
Dependent Claim
21 words
An assembly according to claim 9, further comprising one or more cladding magnets which compensate for flux leakage from the assembly.
Claim 13
Dependent Claim
44 words
An assembly according to claim 9, further comprising one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetisation of the correction magnets being substantially parallel with the direction of magnetisation of the permanent magnet of the assembly.
Claim 14
Dependent Claim
93 words
A nuclear magnetic resonance imaging system comprising a magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that: ##EQU9## where: L g is the length of the gap between the arms, L m is the length of the magnet, B r is the remnant field of the magnet, and B g is the field in the gap.
Claim 15
Dependent Claim
93 words
A nuclear magnetic resonance imaging system comprising a magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that: ##EQU9## where: L g is the length of the gap between the arms, L m is the length of the magnet, B r is the remnant field of the magnet, and B g is the field in the gap.
Claim 16
Dependent Claim
32 words
A system according to claim 12, wherein the magnet assembly is mounted such that the arms of the assembly project substantially horizontally and are spaced apart sufficiently to accommodate a human body.
Claim 17
Dependent Claim
13 words
A system according to claim 12, wherein the magnet assembly is vertically adjustable.
Claim 18
Dependent Claim
75 words
A nuclear magnetic resonance imaging system comprising: a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms; and one or more cladding magnets which compensate for flux leakage from the assembly.
Claim 19
Dependent Claim
75 words
A nuclear magnetic resonance imaging system comprising: a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms; and one or more cladding magnets which compensate for flux leakage from the assembly.
Claim 20
Dependent Claim
30 words
A nuclear magnetic resonance imaging system according to claim 15, further comprising: a ferro-magnetic pole piece provided along the face of the permanent magnet and facing towards the working volume.
Claim 21
Dependent Claim
98 words
A nuclear magnetic resonance imaging system comprising: a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms; and one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetization of the correction magnets being substantially parallel with the direction of magnetization of the permanent magnet of the assembly.
Claim 22
Dependent Claim
98 words
A nuclear magnetic resonance imaging system comprising: a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms; and one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetization of the correction magnets being substantially parallel with the direction of magnetization of the permanent magnet of the assembly.
Claim 23
Dependent Claim
30 words
A nuclear magnetic resonance imaging system according to claim 17, further comprising: a ferro-magnetic pole piece provided along the face of the permanent magnet and facing towards the working volume.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-10-15 | 2000-04-15 | 2000-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-15 | 2004-04-15 | 2004-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-15 | 2008-04-15 | 2008-10-15 | $7700.00 | Window Closed / Lapsed |