US4591818A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coil arrangement for generating a high frequency magnetic field
Assignee: Philips Design Ltd
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Filing: 1984-12-12
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Granted: 1986-05-27
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Expires: 2004-12-12
Abstract
Abstract A coil arrangement for generating a high frequency magnetic field in a generally cylindrical volume, e.g. for use in an NMR imaging apparatus, comprises a plurality of conductors (11, 13, 15, 17, 19) extending generally parallel to the axis of the volume at spaced positions around the volume and connection means (25, 27, 29) whereby the conductors are connected in electrically parallel paths for energization from a common source (S). The paths are arranged to have a high self-resonant frequency compared with the frequency of the source, e.g. by being arranged each to comprise a single turn only, and the impedances of the paths are arranged to differ so that when energized the fields produced by the individual conductors combine to produce a resultant desired field distribution. By having parallel paths of high self-resonant frequency and different impedance the difficulty of providing a sufficient number of series connected turns distributed so as to obtain a desired field distribution without having a low self-resonant frequency is avoided.
Inventors
- 👤 Peter C. Butson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:31
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/32; G01R33/34; G01R33/34046; G01R33/34069; G01R33/34076
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
102 words
A coil arrangement for generating a high frequency magnetic field in a generally cylindrical volume comprising: a plurality of conductors extending generally parallel to the axis of the volume and disposed at spaced positions around the volume; and connection means whereby the conductors are connected in electrically parallel paths for energisation from a common source; the self-resonant frequency of each path being high compared with the frequency of said source, and the impedances of the parallel paths differing so that the fields produced by the individual conductors when energised combine to produce a resultant field in the volume of a desired distribution.
Claim 2
Dependent Claim
102 words
A coil arrangement for generating a high frequency magnetic field in a generally cylindrical volume comprising: a plurality of conductors extending generally parallel to the axis of the volume and disposed at spaced positions around the volume; and connection means whereby the conductors are connected in electrically parallel paths for energisation from a common source; the self-resonant frequency of each path being high compared with the frequency of said source, and the impedances of the parallel paths differing so that the fields produced by the individual conductors when energised combine to produce a resultant field in the volume of a desired distribution.
Claim 3
Dependent Claim
15 words
An arrangement according to claim 1 wherein each said parallel path comprises a single turn.
Claim 4
Dependent Claim
73 words
An arrangement according to claim 1 wherein the parallel paths are connected to said source so that the current in the conductors lying on one side of a plane bisecting the volume and containing its axis is in the opposite direction to the current in the conductors lying on the other side of said plane, and the impedances of the parallel paths vary inversely with the distances of the conductors from said plane.
Claim 5
Dependent Claim
33 words
An arrangement according to claim 3 wherein the conductors on one side of the said plane are in mirror image positions with respect to the conductors on the other side of said plane.
Claim 6
Dependent Claim
27 words
An arrangement according to claim 4 wherein the conductors on each side of said plane are at equally spaced angular positions around the axis of the volume.
Claim 7
Dependent Claim
67 words
An arrangement according to claim 3 wherein said connection means comprises a first connector which electrically connects together one end of all said conductors and two second connectors one of which connects together the other ends of the conductors lying on one side of said plane, and the other of which connects together the other ends of the conductors lying on the other side of said plane.
Claim 8
Dependent Claim
22 words
An arrangement according to claim 6 wherein said first connector is of circular form and said second connectors are of semi-circular form.
Claim 9
Dependent Claim
31 words
An arrangement according to claim 1 wherein the required differences of the impedances of the parallel paths is obtained at least partly by virtue of said conductors themselves having different impedances.
Claim 10
Dependent Claim
19 words
An arrangement according to claim 8 wherein said conductors have different impedances by virtue of having different cross-sectional areas.
Claim 11
Dependent Claim
42 words
An arrangement according to claim 1 wherein the required variation of the impedances of the parallel paths is obtained at least partly by virtue of impedances of different values connected in said paths in series with at least some of said conductors.
Claim 12
Dependent Claim
20 words
An arrangement according to claim 10 wherein said impedances connected in said paths in series with said conductors are inductances.
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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) | 1989-05-26 | 1989-11-25 | 1990-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-26 | 1993-11-25 | 1994-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-26 | 1997-11-25 | 1998-05-27 | $7700.00 | Window Closed / Lapsed |