Patent US4740772A successfully refreshed from Google Patents.
US4740772A
Expired / Lapsed
US
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Gradient coil for image formation devices using nuclear magnetic resonance
Assignee: General Electric CGR SA
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Filing: 1986-10-15
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Granted: 1988-04-26
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Expires: 2006-10-15
Abstract
Abstract The object of the invention is an improved gradient coil. The improvement consists in making steps in the saddle-shaped conductors that form the coil in order to modify local distortions in the magnetic field produced. It is shown that the correction thus made has little effect on the rest of the field of distribution.
Inventors
- 👤 Claude Prevot
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:11
CPC Classifications
H; H01; H01F; H01F7/00; H01F7/06; H01F7/20; G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/385
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
74 words
Gradient coil for apparatus forming images by nuclear magnetic resonance of a type comprising conductors, each shaped around a cylinder, these conductors being assembled in an even number of identical arrangements which are symmetrical with respect to the centre of a pre-determined space of examination, wherein at least one of the conductors of each arrangement has at least one step which spacially deviates the path of an electric current which passes through said conductor.
Claim 2
Dependent Claim
74 words
Gradient coil for apparatus forming images by nuclear magnetic resonance of a type comprising conductors, each shaped around a cylinder, these conductors being assembled in an even number of identical arrangements which are symmetrical with respect to the centre of a pre-determined space of examination, wherein at least one of the conductors of each arrangement has at least one step which spacially deviates the path of an electric current which passes through said conductor.
Claim 3
Dependent Claim
17 words
Coil according to claim 1 wherein the conductors are each shaped according to a so-called saddle contour.
Claim 4
Dependent Claim
45 words
Coil according to claim 1 wherein the even number of arrangements is equal to 4 and wherein the arrangements are equally symmetrical in relation to an axis of symmetry which is parallel to the cylinder and passes through the centre of the space under examination.
Claim 5
Dependent Claim
39 words
Coil according to claims 2 or 3 wherein each arrangement presents a plane of symmetry which passes through the axis of symmetry of the arrangements and wherein the steps of a conductor are symmetrical with respect to this plane.
Claim 6
Dependent Claim
66 words
Coil according to claim 4 wherein the conductors have two arch-shaped parts around a cylinder, linked by two parts which are co-linear with the generators of this cylinder, wherein the steps are placed in an arch which is as close as possible to the space under examination, so as to correct the field distortions that appear in a plane passing through the centre of the space.
Claim 7
Dependent Claim
62 words
Coil according to claim 4 wherein the conductors have two arch-shaped parts around a cylinder, linked by two parts which are co-linear with the generators of this cylinder, wherein the steps are placed in an arch which is furthest from the space under examination, so as to correct field distortions that appear in a plane passing through the periphery of the space.
Claim 8
Dependent Claim
56 words
Coil according to claim 4 wherein the conductors have two arch-shaped parts around a cylinder, linked by two parts which are co-linear with the generators of this cylinder, wherein the steps are placed on those conductors that have cylindrical coordinates similar to the cylindrical coordinates of the field distortions which they have the task of reducing.
Claim 9
Dependent Claim
32 words
Coil according to any one of claims 1 to 3 wherein the steps are shaped like notches, with an orientation perpendicular to the cylinder generators which determine the shape of the conductor.
Claim 10
Dependent Claim
35 words
Coil according to any one of claims 1 to 3 wherein the steps are shaped like blades with their plane forming a given angle with the cylinder generators that determine the shape of the conductors.
Claim 11
Dependent Claim
27 words
Coil according to claim 5 wherein the steps are placed in the arch-shaped parts and have a length ranging from about 5% to 10% of these arches.
Claim 12
Dependent Claim
30 words
Coil according to claim 5 wherein the steps are placed in the arch-shaped parts and have a height ranging from about 5% to 10% of the altitude of these arches.
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) | 1991-04-26 | 1991-10-26 | 1992-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-26 | 1995-10-26 | 1996-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-26 | 1999-10-26 | 2000-04-26 | $7700.00 | Window Closed / Lapsed |