US2882904A - Flexible induction electrode - Google Patents

Description

APril 21, 1959 s. K. RASMUSSEN 2,882,904

FLEXIBLE INDUCTION ELECTRODE Filed April 7, 1954 2 Sheets-Sheet 1 April 21, 1959 s. K. RAsMussEN 2,882,904 FLEXIBLE INDUCTION ELECTRODE Filed April 7. 1954 2 Sheets-Sheet 2 United States Patent C) FLEXIBLE INDUCTION ELECTRODE Sherrill K. Rasmussen, Milton Junction, Wis., assignor to The Burdick Corporation, Milton, Wis., a corporation of Delaware Application April 7, 1954, Serial No. 421,612

7 Claims. (Cl. 128-418) This invention relates to a therapeutic applicator and, more particularly, to a flexible induction electrode for applying high frequency oscillations to a desired object.

It is an object of the present invention to provide a new and improved therapeutic applicator.

Another object is to provide an improved flexible induction electrode for applying high frequency oscillations.

A still further object of this invention is to provide a flexible applicator having an improved construction permitting the symmetrical location of the applicator terminals.

Another object is to provide a flexible induction electrode including new and improved means for preventing both the displacement of electrical conductors from the electrode and the application of excessive forces to the induction element forming a portion of the electrode assembly.

In accordance with these and many other objects, one embodiment of the invention comprises a flexible body of insulating material forming a cavity within which is mounted a flexible flat convolute induction element, the ends of which are spaced different distances inwardly from the edge of the insulating body. The body member is provided with a pair of symmetrically located and spaced hollow flexible protuberances forming terminal assemblies through which extend conductors interconnecting an external power supply with the ends of the induction element. These terminal assemblies include elongated portions extending generally along the longitudinal axis of the induction electrode to permit the conductors to be electrically connected to the ends of the induction element without requiring the terminal assemblies to be incongrously spaced in accordance with the actual location of the ends of the induction element. The terminal assemblies also include strain relief means for preventing the application of the excessive forces to the flexible induction element and for preventing the external connectors from being displaced from the induction electrode assembly.

Many other objects and advantages of the present invention will be apparent from a consideration of the following specification when read in conjunction with the drawings wherein:

Fig. 1 is a top plan view of a flexible induction electrode embodying the present invention;

Fig. 2 is a front elevational view of the electrode shown in Fig. 1;

Fig. 3 is an enlarged cross sectional view taken along line 33 in Fig. 1 showing the construction of a terminal;

Fig. 4'is a bottom plan view of the applicator shown in Fig. 1 with a lower cover member removed;

Fig. 5 is an enlarged fragmentary cross sectional View taken along line 55 in Fig. 1 showing the terminal construction; and

Fig. 6 is a perspective view showing a typical applicationof the flexible induction electrode embodying the present invention.

. Referring now to Figs. 1, 4, and 6 of the drawings, a

flexible induction electrode, indicated generally as 10, comprises a body 12 of flexible dielectric material such as molded rubber having a shallow recess 14 within which is secured, as by cement, a flexible flat convolute body of electrically conductive material forming an induction electrode element 16. A cover member 18 (Figs. 3 and 5) is secured to the body member 12 and the induction element 16 to enclose the latter. The induction element is electrically connected to an external source of power (not shown) by means of a pair of insulated cables 20 which extend into the body 12 of the electrode 10 through a pair of terminal assemblies indicated generally as 22 and 24. The ends of the cables 20 are provided with insulated plugs 26 which are received within jacks (not shown) on the external source of power.

The electrode 10, in being formed entirely of flexible materials, readily conforms to the configuration of the object to which the high frequency oscillations are to be applied and thus facilitates the maximum transmission of oscillatory energy from the electrode 10 to the object. As shown in Fig. 6, the electrode 10 may be positioned on portions of the human body and secured in position thereon by a flexible strap 28, both ends of which are detachably secured to the body of the electrode 10.

Referring now to the induction element 16, this may be formed in a flat convolute configuration by stamping a sheet of electrically conductive material, such as copper or a'copper alloy. The thickness of the sheet is so chosen that it is thin enough to be readily flexible but is also thick enough to prevent buckling or permanent physical distortion of the element 16 when this element is flexed during the application of the electrode 10 to an object. The thickness may be about .0l0-.012 inch which is approximately the depth of the recess 14. Further, in addition to being electrically conductive, the material forming the element 16 is preferably somewhat resilient so that this element will return to a normal uniplanar configuration when the electrode 10 is removed from the object to which the high frequency energy is applied.

The convolute induction element 16 of the present invention is formed so that a pair of ends 30 and 32 thereof lie on substantially a centrally disposed line extending longitudinally relative to the element 16. The end 32 is spaced inwardly from the edge of the body 12 a greater distance than the end 30 to permit the element 16 to be formed by a single stamping operation on a unitary metal blank, but the terminal assemblies 22 and 24 are symmetrically located with respect to the outer configuration of the body member 12.

Referring now to the terminal assemblies 22 and 24, each of these assemblies includes a hollow receptacle or sleeve 36 integrally connected with the body 12 by a skirt portion 38 which is enlarged or elongated in a direction generally corresponding to the longitudinal axis of the electrode 10. The walls defining the sleeve 36 and the skirt portion 38 may be slightly thicker than those forming the body 12 in order to provide strong securing means for the cables 20.

In order to connect the induction element 16 with the external source of power, a pair of hollow flexible braided conductors 40 are provided. As shown in Fig. 4, the end 56 of one of the conductors 40 is secured to the outer end 36 of the induction element 16, and this conductor extends outwardly through the terminal assembly 24 into a flexible insulating covering or sleeve 42 forming a part of one of the cables 20. An end 56 of the other conductor 40 is secured to the inner end 32 of the element 16 and extends outwardly through the terminal assembly 22 into an insulating sleeve 42 forming a part of the other cable 20. It is desirable to use the hollow braided type of conductor 45] shown in the drawings rather than conventional solid electrical conductors in order to reduce the loss of energy in transmitting the high frequency oscillations from the external source to the induction element 16. V

.Apleasing appearance is provided by locating- terminal assemblies 22 and 24 symmetrically with respect to the body 12 of the inductor 10 even though the ends 30 and 32 f the induction element 16, to which the conductors 40 must be connected, are not symmetrically located relative to, the exterior configuration of the inductor 10. However, the provision of the enlarged portions 38 extending substantially along the longitudinal axis of the body member 12 permits the conductors 40 to be electrically connected to the ends of the induction element 16 irrespecfive of their spacing relative to the edge of the body member 12 while permitting the terminal assemblies 22 and 24 through which these conductors pass to be located in identical positions relative to the external-configuration "of the electrode 10.

'40 extending through the terminal assembly 24 is displaced, to the right and is connected to the outer end 30 ofthe induction element 16. Further, the end of the conductor 40 extending through the terminal assembly '22 is also displaced to the right, as shown in Fig. 4, land is electrically connected to the inner end 32 of the induction element 16, which end 32 is displaced inwardly from the edge of the body member 12 a greater distance than is the end 30. Obviously, the induction element 16 could be positioned oppositely to that shown in Fig. 4 and the enlarged portions 38 of the terminal assemblies 22 and 24 would permit a similar interconnection of the conductors 40 with this element.

- In order to prevent the displacement of the conductors 40 from within the terminal assemblies 22 and 24 and also to prevent the application of excessive forces to the flexible induction element 16, strain relief means are provided in each of these terminal assemblies. As shown in Figs. 3 and 5, the sleeve 36 is provided with an internal tapered wall 44 terminating in a shoulder 46. A rigid dielectric plug 48 having a tapered annular outer wall 50 is seated in the sleeve 36 so that a shoulder 52 thereon engages the shoulder 46 and so that the tapered wall 50 engages the tapered wall 44. The tapered walls 44 and 50 and the interlocked shoulders 46 and 52 positively prevent the plug 48 from being displaced from the sleeve .36. The tubular body of the conductor 40 extends through an opening 54in the plug 48.

In order to secure the conductor 40 to the strain relief plug 48, the end 56 of the conductor 40 is flattened (after removal of the central filling, if one is present in the conductor) so that the width of this flattened portion exceeds the diameter of the opening 54 and this flattened portion is soldered, as indicated at 58, to provide a rigid projection engaging the lower edge of the rigid plug 48. Also, a drop of solder or similar securing means 59 may be applied to the conductor 40 above the plug 48 to prevent the conductor from being forced into the enlarged portion 38. In this manner, the force applied to the conductor 40, which tends to pull this conductor out of the terminal assemblies 22 and 24, is directly transmitted through the rigid plug 48 to the flexible structure forming the terminal assemblies. Accordingly, the strain relief plug 48 not only prevents the conductor 40 from being displaced from within the terminal assemblies 22 and 24 but also prevents this conductor from being pulled out of electrical contact with the flexible induction element 16.

In order to provide means for both securing the insulating sleeve 42 to the terminal assemblies 22 and 24 and for maintaining this sleeve in a spaced relation to the braided conductor 40, the rigid plug 48 is provided with an integral sleeve portion 60. The end of the flex ible sleeve 42 is inserted between the inner wall of the sleeve 36 and the outer surface of the sleeve 60 and is resiliently held in engagement therewith to secure the location of the terminal assemblies 22 and 24, the (Di/$1 1 4 sleeve 42 to the terminal assemblies 22 and 24 and to also maintain the spacing between the braided conductor 40 and the inner surface of the insulating sleeve 42.

To provide a completely sealed enclosure for the flexible induction element 16, the body 12 of the induction electrode 10 is provided with a recessed ledge 64 (Fig. 4) and a lip 66 defining a peripheral U-shaped channel. The cover member 18 is coated with cement and this member is then placed on the body member 12 with the peripheral portion thereof received within the channel formed by the lip 66. The cement produces a bond between the peripheral portion of the cover member 18 and the ledge 64, and the cement on the remaining portions of the cover member 18 produces a bond between this member and the outer surface of the flexible induction element 16 and body member 12, thereby positively securing the element 16 in a desired position on the induction. electrode 10, as shown in Figs. 3- and 5.

.- As shown in Fig. 4 of the drawings, the conductor I Toincfease the-flexibility f thelinduiml ball the body member 12 and the cover member 18 are provided with a plurality of transversely extending ribs 70 and 72, respectively. These ribs increase the flexibility of the electrode 10 to permit this element to conform to the outer configuration of the human body, as shown in Fig, 6, but increase the rigidity of the electrode 10 insofar as deflection or flexure about a longitudinal axis is concerned soas to maintain the edges of the electrode in contact with the object. Further, the provision of the ribs. provides a means for desired spacing of the in duction element 16 from the object and for permitting a flow of air between the surface of the object and the electrode 10 thereby to reduce undesirable heating effects. The electrode 10 is detachably mounted on a human body by the flexible securing means 28 which is provided at each end thereof with a plurality of longitudinally spaced'apertures 76. In order detachably to secure the flexible securing means 28 to the electrode 10, a pair of fasteners 78 are provided. These fasteners extend through slots 80 and 82 in the body 12 and the covering member 18 and include flanged portions 84 and 86 (Fig. 5) for maintaining the fasteners 78 within these slots. The upper end of the fastener 78 is tapered, as indicated at 90, and is provided with a neck portion 92. When one of the apertures 76 is placed on the tapered portion 90 and the strap 28 is pressed downwardly toward the flange 86, the material defining the opening 76 is distorted and subsequently snaps back into engagement with the neck portion 92, thereby detachably securing the flexible strap 28 to the induction electrode 10. As shown in Fig. l of the drawings, the flexible stra 28'is1 secured to the induction electrode 10 at points thereon which are in substantial alignment with and are closely adjacent to the terminal assemblies 22 and 24. Therefore, the forces applied to the body 12 of the electrode 10, due either to manipulation of the cables 20 or to the Weight thereof, are directly transmitted from the terminal assemblies 22 and 24 to the flexible securing means 28 without being transmitted through an appreciable length of the body member 12. Since these forces are directly transmitted to the supporting means through the relatively strong constructions forming the terminal assemblies 22 and 24, excessive stresses are not applied to the relatively thin material forming the flexible body 12. Accordingly, the flexible induction electrode 10 provides a new and improved construction utilizing an easily and cheaply fabricated flat flexible convolute induction element 16 which is completely sealed within a flexible in sulating body and in which the inner and outer ends there: of are adapted to be connected to an external source of power through terminal assemblies symmetrically dis posed with respect to the outer configuration of the electrode 10.- I-lurther, by the advantageous formation of the body member 12 and covering member 18 and by a proper alL; flexibility of the induction; electrode .10. is increased thereby to permit this electrode to readily conform to the configuration of the object to which it is applied without structurally weakening tre electrode to the extent that this electrode cannot be held in intimate engagement with this object. The provision of strain relief means in the terminal assemblies 22 and 24, which are of increased structural strength, not only prevents the application of excessive forces to the flexible induction element 16 and prevents the conductors 20 from being displaced from the electrode 10 but also results in the transmission of forces substantially directly fromthe cables 20 to the flexible supporting means 28.

While the present invention has been described in connection with the details of a specific embodiment of the invention, it should be understood that these details are not to be construed as a limitation of the invention except insofar as set forth in the accompanying claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A therapeutic electrode comprising a relatively thin flexible body having a recess therein, a flexible convolute layer of electrically conductive material mounted in said recess, said convolute layer having a pair of terminals positioned different distances from the edge of said body, hollow means communicating with said recess and symmetrically mounted on said flexible body, said hollow means having enlarged portions extending longitudinally of said body and over said terminals, conductors connected to said terminals and extending through said hollow means, and said flexible body including means for securing said body to an object, said securing means being fastened to said body at spaced points in line with said terminals and including apertured strap means and fastening means secured to said body at spaced points thereon, said fastening means including two spaced portions of reduced diameter, a first of said reduced diameter portions being engaged by said body and the second of said reduced diameter portions being detachably received within one of the apertures in said strap means.

2. A therapeutic electrode comprising a generally flat backing member formed of flexible material having a recess substantially coextensive with said backing material and a pair of relatively rigid spaced hollow receptacles formed therein, said spaced hollow receptacles communicating with said recess and extending outwardly from said backing member, a flat convolute body of flexible electrically conductive strip material mounted in said recess, a cover member formed of flexible material and secured to said backing member to enclose said flat body within said electrode, electrically conductive means connected to spaced points on said body and extending through said hollow receptacles, and strain relief means mounted in said receptacles and including means engaging said conductive means to prevent forces applied to said conductive means frombeing transmitted to said flat body and to cause said forces to be transmitted to said relatively rigid receptacles.

3. A therapeutic electrode comprising a body of flexible material having a cavity therein, a flexible flat convolute lamina of electrically conductive material mounted in said cavity, a hollow member in communication with said body and having an enlarged hollow flexible portion connecting a narrow portion thereof to said body and extending transversely of the axis of the body, and a conductor connected to said convolute lamina and extending out of said cavity through said hollow member, said con- 6 ductor having insulation secured to said hollow member at said narrow portion thereby to prevent displacement of said conductor from said body.

4. A therapeutic electrode comprising a flexible body defining a recess, flat convolute conducting means motmted in said recess, flexible hollow means mounted on said body in communication with said recess, said hollow means having a constricted portion, rigid means defining an opening and mounted in said constricted portion, a flexible braided hollow electrical conductor connected to said conducting means and extending through said opening, said braided conductor being flattened at a point adjacent said rigid means, and means for maintaining said braided conductor in a flat configuration so that forces applied to said conductor are transmitted to said rigid means.

5. A therapeutic electrode comprising an elongated flexible body formed of flexible material and having a recess therein, a flat convolute layer of electrically conductive material mounted in said recess, a cover formed of flexible material and secured to said body for closing said recess to define a cavity within which the electrically conductive material is received, and ribs formed in said body and said cover extending transversely thereto to permit said electrode to be flexed laterally and to resist longitudinal flexure thereof, said ribs on said cover also spacing said electrode from an object to which said electrode is applied.

6. A therapeutic electrode comprising a flexible body having a shallow recess of a predetermined depth therein, a flat stamped lamina of electrically conductive material mounted in said recess, the thickness of said lamina eing approximately equal to said predetermined depth, said stamped lamina having a pair of terminals positioned different distances from the edge of said body, hollow means communicating with said recess and symmetrically mounted on said flexible body, said hollow means having enlarged portions extending over said terminals, and conductors connected to said terminals and extending through said hollow means.

7. A therapeutic electrode comprising a flexible body having a first recess of a predetermined depth therein, a fiat layer of electrically conductive material mounted in said first recess, the thickness of said layer being approximately equal to said predetermined depth, said layer having a pair of terminals positioned different distances from the edge of said body, hollow means in communication with said recess and symmetrically mounted on said flexible body, said hollow means having enlarged portions extending over said terminals, conductors connected to said terminals and extending through said hollow means, said body having a second recess therein, means formed integral with said body and cooperating with said second recess to form a channel, and a flexible plate received in said channel and secured to said second recess for enclosing said flat layer.

References Cited in the file of this patent UNITED STATES PATENTS 1,975,518 Rose Oct. 2, 1934 2,110,392 Don Mar. 3, 1938 2,404,283 Gieringer July 16, 1946 2,476,645 Wantzenberg July 19, 1949 2,509,417 Bowers May 30, 1950 2,583,853 Kazdin Jan. 29, 1952 UNITED STATES PATENT OFFICE Q CERTIFICATE OF CORRECTION Patent Noo 2,882,904 April 21, 1959 Sherrill Ko Rasmussen It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line- 18, strike out ilexible", first occurrence; line 19, after "flat" insert flexible Signed and sealed this 8th day of December 1959 (SEAL) Attest:

KARL Ho AXLINE Attesting Officer ROBERT C. WATSON Commissioner of Patents

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