Magnetic field applicator for the magnetic stimulation of body tissues

Abstract

A magnetic field applicator for the magnetic stimulation of body tissues comprising a core carrier (1) in which a plurality of magnetically conductive flow guide pieces comprised of layered iron sheets is disposed, upon which at least one live coil (3) is disposed that generates an upward-emitted magnetic field having a plurality of field line bundles (8), wherein the magnetic field applicator comprises a polygonal coil (3) that is wound as a pancake coil in one or more planes in such a way that the direction of the individual coil conductors (27) is selected such that the coil conductors (27) run in pieces in a predominantly straight line and perpendicular to the plane of the flow guide pieces that are made of layered sector iron cores (5-8).

Claims

1. A magnetic field applicator for magnetic stimulation of body tissues comprising a core carrier (1) in which a plurality of magnetically conductive flow guide pieces comprised of layered iron sheets is disposed, upon which at least one live coil (3) is disposed that generates an upward-emitted magnetic field having a plurality of field line bundles (18), wherein the magnetic field applicator comprises a polygonal coil (3) that is wound as a pancake coil in one or more planes in such a way that direction of individual coil conductors (27) is selected such that the coil conductors (27) run in pieces in a predominantly straight line and perpendicular to a plane of the flow guide pieces that are made of layered sector iron cores (5-8), wherein the sector iron cores (5-8) are poured into the core carrier (1) with a magnetically conductive, electrically insulating, vibration-absorbing, hardening plastic material.

2. The magnetic field applicator according to claim 1, wherein the sector iron cores (5-8) disposed evenly on a circumference of the core carrier (1), said sector iron cores forming a virtually closed iron body on whose top and/or bottom side the coil conductors (27) of the coil (3) are disposed.

3. The magnetic field applicator according to claim 2, wherein the coil (3) is embodied as a rectangular or triangular coil.

4. The magnetic field applicator according to claim 3, wherein the coil conductors have a rectangular shape with a cross-section defined by a plurality of conductive wires that are twisted and insulated from one another.

5. The magnetic field applicator according to claim 4, wherein the coil conductors are oriented upright relative to a plane of the sector iron cores (5-8).

6. The magnetic field applicator according to claim 5, wherein the upwardly emitted magnetic field has an approximately spherical shape.

7. The magnetic field applicator according to claim 6, wherein the core carrier (1) comprises a shell opening upward made of a magnetically and electrically nonconductive material and the sector iron cores (5-8) are placed in receiving spaces (25) separated by bars (9-12) in the core carrier.

8. The magnetic field applicator according to claim 1, wherein each sector iron core (5-8) comprises a plurality of iron sheets (15), and a layering direction of the plurality of iron sheets (15) lies perpendicular to circumferential edges of the sector iron cores (5-8).

9. The magnetic field applicator according to claim 1, wherein a ratio of a length (40) of the coil conductors (27) laid in a straight line to a length of the coil conductors (27) laid in a bend radius (41) is a ratio of 10:1 up to 50:1.

10. A magnetic field applicator for magnetic stimulation of body tissues comprising: a core carrier (1); a plurality of magnetically conductive electrically insulating flow guide pieces comprised of layered iron sheets forming layered sector iron cores (5-8) and disposed on the core carrier (1); at least one live coil (3) disposed on the plurality of magnetically conductive flow guide pieces that generates an upward-emitted magnetic field having a plurality of field line bundles (18), wherein the at least one live coil (3) comprises a polygonal coil (3) that is wound as a pancake coil in one or more planes, the polygonal coil (3) comprising individual coil conductors disposed in a in a predominantly straight line and perpendicular to a plane of the plurality of magnetically conductive flow guide pieces, and wherein the sector iron cores (5-8) are poured into the core carrier (1) with a magnetically conductive, electrically insulating, vibration-absorbing, material.

11. The magnetic field applicator according to claim 10, wherein the sector iron cores (5-8) disposed evenly on a circumference of the core carrier (1), said sector iron cores forming a virtually closed iron body on whose top and/or bottom side the coil conductors (27) of the coil (3) are disposed.

12. The magnetic field applicator according to claim 10, wherein the coil (3) is embodied as a rectangular or triangular coil.

13. The magnetic field applicator according to claim 10, wherein the coil conductors have a rectangular shape with a cross-section defined by a plurality of conductive wires that are twisted and insulated from one another.

14. The magnetic field applicator according to claim 10, wherein the coil conductors are oriented upright relative to a plane of the sector iron cores (5-8).

15. The magnetic field applicator according to claim 10, wherein the upwardly emitted magnetic field has an approximately spherical shape.

16. The magnetic field applicator according to claim 10, wherein the core carrier (1) comprises a shell opening upward made of a magnetically and electrically nonconductive material and the sector iron cores (5-8) are placed in receiving spaces (25) separated by bars (9-12) in the core carrier.

17. The magnetic field applicator according to claim 10, wherein each sector iron core (5-8) comprises a plurality of iron sheets (15), and a layering direction of the iron sheets (15) lies perpendicular to circumferential edges of the sector iron cores (5-8).

18. The magnetic field applicator according to claim 10, wherein a ratio of a length (40) of the coil conductors (27) laid in a straight line to a length of the coil conductors (27) laid in a bend radius (41) is a ratio of 10:1 up to 50:1.

Description

(1) The invention shall be described in greater detail below with reference to drawings showing the multiple exemplary embodiments. Additional features and advantages essential to the invention may be found in the drawings and their description.

(2) Shown are:

(3) FIG. 1 a perspective exploded view of a first embodiment of a magnetic field applicator in the form of a rectangular coil,

(4) FIG. 2 a perspective top view of the arrangement according to FIG. 1,

(5) FIG. 3 a top view of a modified first embodiment,

(6) FIG. 4 a top view of a modified second embodiment,

(7) FIG. 5 a depiction of the rectangular coil rotated 90° as compared to FIG. 1,

(8) FIG. 6 a perspective depiction of a top view of the core carrier,

(9) FIG. 7 a perspective view of the coil with the coil carrier,

(10) FIG. 7A a cross section of a rectangular conductor,

(11) FIG. 7B a schematic view of the path of the round strand in the rectangular conductor,

(12) FIG. 8 the field line paths of the coil with a sector iron core on one side of the rectangular coil,

(13) FIG. 9 a schematic and highly simplified view of the rectangular distribution of the magnetic field resulting from the magnetic field path according to FIG. 8,

(14) FIG. 10 a comparison of the magnetic field strengths along the path relative to the surface of the rectangular coil,

(15) FIG. 11 a schematic view of the path of the rectangular conductor relative to the layered iron sheet and depiction of the magnetic field resulting therefrom.

(16) FIG. 1 shows a schematic depiction of the structure of a magnetic field applicator designed as a rectangular coil. It essentially comprises a lower core carrier 1 having an approximate shell shape and preferably made of a plastic material. The plastic material forms a shell that is open in the upward direction and in the interior of which a number of bars 9, 10, 11 running inward in an approximate star shape are disposed. The shell is shown again in FIG. 6 in an enlarged depiction. The depiction in FIG. 6 and its description are hereby incorporated by reference.

(17) A total of four receiving spaces 25 is formed in the shell that are formed by the bars 9, 10, 11 running radially inward, with the bars 9, 10, 11 meeting in the central region in the vicinity of a spacer 12 on which a guide part 26 is disposed in a raised fashion. The guide part 26 serves to screw the upper cover plate formed by the coil carrier 2 onto the top of the core carrier 1.

(18) Supporting elements 14 are disposed in the receiving spaces 25 of the core carrier 1 on the base side, with a total of four sector iron cores 5, 6, 7, 8 being placed upon said supporting elements such that the receiving space 25 is filled by the inserted sector iron core.

(19) In the depictions according to FIG. 1 and FIG. 6, two receiving spaces 25 are filled with associated sector iron cores 7, 8 or the sector iron cores 7, 8 have already been placed there.

(20) The bars 9-12 comprise upward-directed recesses 13 that are suitable for filling with a thermosetting coercive material. This material may be, for example, a thermosetting plastic material enriched, for example, with cobalt shavings in order to also produce a magnetically conductive surface on the faces of the sector iron cores 5-8 so as to allow the most complete conducting level possible below the coil carrier and the coil 3.

* * *

(21) It is preferable for the highly coercive casting material to be an elastomer that is able to absorb and dampen any vibrations of the sector iron cores 5-8.

(22) It is important for each sector iron core 5-8 to be comprised of a plurality of iron sheets 15 that are stacked and insulated from one another and that are embodied, for example, as transformer sheets.

(23) Therefore, in order to create such a sector iron core 5-8, an approximately square or rectangular basic form is produced in which a plurality of iron sheets 15 placed upright is disposed. These iron sheets are adhered to one another, for example. Using a suitable laser cutting method, the required contours of the individual sector iron cores 5-8 are cut out so as to obtain the shape according to FIGS. 2 to 4.

(24) Instead of the laser cutting method, the iron sheet packet may be sawed in a mechanical fashion and the sawed faces may be ground in order to prevent the iron sheets from touching one another in their sawed face region.

(25) The iron sheets 15 are therefore electrically insulated from one another and, for example, designed as transformer plates.

(26) It is important for the layering of the iron sheets 15 to be designed in such a way that they are located upright and perpendicular to the coil plane of the coil 3. This will be described in greater detail with reference to FIG. 11.

(27) The sector iron cores 5-8 that are placed in the receiving spaces 25 of the core carrier 1 are covered above by an insulation plate 4 made of an electrically insulating plastic.

(28) The insulation plate 4 serves as a cover plate for the coil 3 disposed thereabove, which is accommodated in a coil carrier 2.

(29) Additional details will be provided with reference to FIGS. 6 and 7.

(30) FIG. 2 shows a schematic top view of a rectangular coil 20 according to FIG. 1. It may be seen that the layering direction of the iron sheets 15 is always located perpendicular to the circumferential edges of the sector iron cores 5, 8 and that the field line bundle 18 resulting therefrom is always directed outward, for example, upward, such that the field line bundle 18 runs on the same plane as the plane of the iron sheets 15. This is shown in greater detail in FIG. 8 and FIG. 11.

(31) Therefore, in the exemplary embodiment according to FIGS. 2 to 4, it is important for all of the coil wires of the coil 3 to run in a straight line to the greatest extent possible, i.e., for the bend radii located therebetween to be minimized, and for said wires to be disposed parallel to one another and to lie in the same plane. The invention is not limited to the arrangement of the coil conductor wires in the coil 3 in a single plane. Likewise, in a different embodiment, it is possible for multiple planes of coil conductor wires to overlap. Instead of a single coil, therefore, it is also possible for multilayer coils to be present.

(32) FIG. 3 shows a polygonal coil 21 instead of a rectangular coil 20 according to FIG. 2, with the same reference characters being used for the same parts. Here, it may be seen that differently shaped sector iron cores 5, 5a, 6, 6a, and 7, 7a are present; said sector iron cores should rest against one another on the edges to the greatest extent possible and the gap 16 resulting therefrom should be minimized to the greatest extent possible.

(33) For reasons of better clarity alone, the layer directions of the iron sheets 15 are shown in an exaggerated fashion, just as the width of the gap 16 is shown in an exaggerated fashion.

(34) Likewise, the figures show that a central recess is formed in the interior of the coil 3. The central recess 17 is formed by the inner circumference of the sector iron cores 5-8 adjacent to one another. However, the invention is not limited to this. The sector iron cores 5 may also extend completely into the inner space such that the central recess 17 approaches zero or disappears entirely.

(35) Furthermore, FIG. 4 shows another arrangement of sector iron cores 5, 6, 7 that combine to form a triangular coil 22.

(36) In addition to these basic shapes according to FIGS. 2 to 4, all combinations of the arrangements of the coils 20-22 shown in FIGS. 2 to 4 may be provided. In all embodiments, it is important for the layer orientation of the layered iron cores 15 in the individual sector cores 5-8 to be perpendicular to the longitudinal extension of the conductor wires of the coil 3, as will be shown below with reference to FIG. 11.

(37) With this technical teaching, an extraordinarily high upward-directed field line concentration is achieved for the first time in which an approximately spherical field is obtained that extends above the central recess 17 and generates only a small amount of heat with a small amount of eddy current losses. This result has not been possible up to now.

(38) FIG. 5 shows a depiction of a rectangular coil 20 according to FIG. 1 rotated by 90°, with the interior view of the coil carrier 2 being discernible. The coil carrier is preferably made of a plastic material into which the guide tracks 24 have been ground in which the individual spiral-wound rectangular conductors 27 of the coil 3 are placed and insulated from one another.

(39) The coil 3 placed in the guide tracks 24 of the coil carrier 2 can also be poured in.

(40) The coil ends 3a, 3b are guided through recesses in the insulation plate 4, extend through recesses 23 in the core carrier 1, and are connected to a direct current source that is subject to a pulse contact control.

(41) FIG. 6 shows additional details of the structure of the core carrier, which have already been discussed in conjunction with FIG. 1.

(42) While the layer direction of the iron sheets 15 was only partially and schematically filled in in FIG. 1 for the sake of a simpler drawing, FIG. 6 omits the depiction of the layer direction of iron sheets 15.

(43) In a schematic depiction, FIG. 2 shows that, above each sector iron core 5, 6, 7, 8, its own field line bundle 18, 19 is generated and that the field line bundle generated relative to the sector iron cores 5 and 6 was omitted for the sake of improved clarity. Overall, this results in a spherical, upward-directed magnetic field, which will be described below.

(44) Thus, an extensively homogenous magnetic field is generated above the base surface of the magnetic field applicator that is preferably directed upward and that, in its base form, approximately corresponds to the rectangular shape of the applicator. Because, in a preferred embodiment, the applicator is designed as a rectangular coil 20 having a rectangular core carrier 1, the resulting shape is not precisely spherical but rather ovoid.

(45) The coil conductors, for example, the rectangular conductors 27 of the coil 3, should form an extensively straight stretch 40 in comparison to the short bend radii 41. The exemplary embodiments according to FIGS. 2 and 4 approximate this desired ideal. The ratio of the length of the coil conductors laid in a straight line to the length of the coil conductors laid in the bend radius 41 is a ratio of 10:1 up to 50:1. The ratio numbers given here should be considered only examples of length ratios; they do not limit the scope of the invention because they are to be understood only as examples.

(46) FIG. 7 shows the core carrier 1 with the laid sector iron cores 5-8 upon which the coil 3 is placed.

(47) FIG. 7A shows a section of a rectangular conductor 27 of the coil 3. It may be seen that the rectangular volume is filled by a plurality of round strands 28 that are insulated from one another and in that form the longitudinal axis of the rectangular conductor 27 in such a twisted state according to FIG. 7B, such that each round strand runs once along the outer surface of the rectangular conductor and once in the interior space thereof. In this manner, instances of magnetic displacement are prevented.

(48) FIG. 8 shows a schematic view of a field line path of the field line 38 over the upright conductors 27, which form the coil 3, with the same arrangement of sector iron cores being disposed on the opposite side of the recess 17 and symmetrically to the symmetrical axis 30.

(49) Here, it may be seen that a maximum effective field line concentration results on the upper flat side of the sector iron core 5 that also enters on the face side 31 of the sector iron core 5. Only a few field lines are projected downward, resulting in the effectiveness of the sector iron core 5 comprised of layered iron sheets 15.

(50) A high concentration of the field lines is present in the inner space of the sector iron core 5 and only a low magnetic field density is projected downward on the flat side 33.

(51) FIG. 9 shows a schematic and highly simplified view of the desired spherical field that extends over the central recess 17 of the rectangular coil 20 and that extends with the maximum possible field line concentration upward into the abdomen of a human body sitting thereon, preferably into the urogenital tract, and fills this region of the body as homogenously and continuously as possible.

(52) FIG. 10 shows a comparison of the field line strengths (ordinates) over the surface of the rectangular coil 20. It may be seen that the maximum of the field line strengths results above the central recess 17 and that, adjacent to the central region, a decrease 35 decreasing to all sides can be observed. In reality, the field line distribution is three-dimensional and is shown in a simplified fashion for graphic reasons only. The distribution is therefore axially symmetrical and present above the central recess 17.

(53) FIG. 11 shows the principle of the invention. The longitudinal extension 36 of the rectangular conductors 27 extends perpendicular to the plane 39 of the layered iron sheets 15. The iron sheets 15 also form a longitudinal extension 37 that is oriented perpendicular to the longitudinal extension 36 of the rectangular conductors 27. Therefore, a field line bundle 18 results around the longitudinal extension 36 of the rectangular conductor 27, with the field line density being dense in the layered iron sheet 15 and being guided through the iron sheet with a small amount of losses.

(54) Therefore, the plane of the field line bundle 18 is located in the same plane 39 as the layered iron sheets 15. In this manner, only a small amount of eddy currents are generated in the iron sheets 15 and only very minor heat generation results therefrom. For this reason, the magnetic field applicator does not require any cooling, even if very high currents (>1000 A) with short pulses (<1 ms) are applied repetitively up to 250 Hz.

KEY TO DRAWINGS

(55) 1 Core carrier

(56) 2 Coil carrier

(57) 3 Coil

(58) 3a Coil end

(59) 3b Coil end

(60) 4 Insulation plate

(61) 5 Sector iron core

(62) 6 Sector iron core

(63) 7 Sector iron core

(64) 8 Sector iron core

(65) 9 Bar

(66) 10 Bar

(67) 11 Bar

(68) 12 Spacer

(69) 13 Recess

(70) 14 Supporting element

(71) 15 Iron sheet (layered)

(72) 16 Gap

(73) 17 Central recess

(74) 18 Field line bundle

(75) 19 Field line bundle

(76) 20 Rectangular coil

(77) 21 Polygonal coil

(78) 22 Triangular coil

(79) 23 Recess

(80) 24 Guide track

(81) 25 Receiving space

(82) 26 Guide part

(83) 27 Rectangular conductor

(84) 28 Round strand (insulated)

(85) 29 Twisting

(86) 30 Symmetrical axis

(87) 31 Face side

(88) 32 Flat side, upper

(89) 33 Flat side, lower

(90) 34 Maximum

(91) 35 Decrease

(92) 36 Longitudinal extension (of 27)

(93) 37 Longitudinal extension (of 15)

(94) 38 Field line

(95) 39 Planes (of 5-8)

(96) 40 Straight stretch

(97) 41 Bend radius