Hand-Controllable Switching Device for Electrosurgical Instruments

Other objects, advantages and features of the present invention will become more readily appreciated and understood when taken together with the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 is a side view in elevation of a preferred form of switching device for electrosurgical instruments in accordance with the present invention;

FIG. 2 is a longitudinal section view taken about lines 2--2 of FIG. 1;

FIG. 3 is a fragmentary section view of the front blade-receiving end of the preferred form of the device shown in FIGS. 1 and 2 with the blade removed;

FIG. 4 is a cross-sectional view through one of the switch settings taken about lines 4--4 of FIG. 2;

FIG. 5 is a cross-sectional view taken about lines 5--5 of FIG. 2; and

FIG. 6 is a cross-sectional view similar to FIG. 3 illustrating the releasable insertion of a modified form of knife therein.

Referring in detail to the drawings, there is illustrated in FIGS. 1 to 5 a preferred form of hand-controllable switching device for electrosurgical instruments which is broadly comprised of an elongated hollow body 10 containing a pair of longitudinally spaced switch contact elements 11 and 12 arranged in outer spaced concentric relation to an electrical conductor 14 extending longitudinally through the greater length of the body from a point adjacent to one end thereof. The electrical conductor 14 is preferably in the form of a rigid tube sized to permit releasable insertion of the shank end of a blade 16 which extends through the opposite end of the switching device to that of the electrical conductor. Electrical leads 18 and 19 extend through the body from the one end for connection to the switch contact elements 11 and 12, respectively. The switch contact elements 11 and 12 each is correspondingly formed of a substantially rigid metal ring or band positioned to extend circumferentially along inner walls of cavities or recessed areas 20, 21 in the body so that when either of the switch contact elements 11 and 12 is pressed in a radially inward direction, it will make contact with the electrical conductor to effect closure of the switch.

Considering in more detail the construction and arrangement of the switching assembly, preferably each of the switch contact elements 11 and 12 is affixed to an inner wall surface of a collar 24, each collar 24 having an inner flat seating portion 25, a radially extending web 26 provided with circumferentially spaced apertures 27 and an outer circular rim 28. Each collar 24 is preferably composed of a somewhat inflexible or rigid material with an inner circular seating portion 25 of a width less than the length of the cavity 20 or 21 within which it is positioned, and the rim 28 is dimensioned to project beyond the external wall surface of the body 10.

The apertures 27, as best seen from FIG. 4, have the principal function of permitting the material of the body 10 to flow through the collars 24 in the process of molding or curing of the body in a manner to be described into unitary relation to the collars; also, one of the apertures 27, as illustrated in FIG. 2, permits extension of one of the leads 18 through the collar 24 which contains the ring 12 into connected relation to the contact ring 11. The other lead 19 is connected to the collar 12, each lead establishing different power levels for the knife.

Now turning to a more detailed consideration of the construction and arrangement of the body 10, preferably the body is defined by a pliable elongated casing having a slender tapered electrical conductor-receiving end 30 and a thickwalled forwardly tapered, blade-receiving end 32 which are interconnected by an intermediate switch housing portion 34. The intermediate switch housing portion 34 is divided from opposite ends 30 and 32 by circumferential grooves 35 and 36, respectively. The groove 35 merges into an enlarged circumferential rib 38 located adjacent to the rim or button 28 surrounding the contact ring 12, and another rib 39 is located on the opposite side of the rim 28 surrounding contact ring 12 and just rearwardly of the forwardmost rib 28 for contact ring 11. The spaced ribs 38 and 39 facilitate grasping of the hand switching device and ease of identification by the surgeon of each of the circular control buttons 28 for the contact rings 11 and 12.

The leads 18 and 19 extend in diametrically opposed relation to one another through the thickness of the body from a cable 40 which is positioned at the extremity of the electrical conductor-receiving end 30, and a pair of additional leads 41 and 42 extend from the cable through a limited aperture 44 at the rearward extremity of the housing, the leads 41 and 42 being fixed by crimping the end 46 of the conductor tube 14. The body 10 is provided with a main bore 48 for insertion of the conductor tube 14, the main bore being interrupted only by the intermediate cavities 20 and 21 which as referred to earlier are slightly enlarged with respect to the diameter of the main bore and with the contact rings 11 and 12 mounted in flush relation to the walls of the cavities 20, 21.

Preferably, the blade-receiving end 32 is relatively thick-walled with respect to the conductor-receiving end 30 and is provided, as best seen from FIG. 3, with a counterbore 50 which is normally offset with respect to the longitudinal axis of the main bore 48 and has an inner stepped portion or shoulder 52. Thus, when the shank portion 17 of the blade 16 is inserted into the counterbore 50 it will cause its expansion or displacement from the relationship shown in FIG. 3 to that shown in FIG. 2 while being firmly gripped and frictionally engaged by the inner wall surface of the counterbore 50. As further illustrated in FIG. 2, the shank portion 17 has an outer sleeve 54 composed of a non-conductive material which will serve to snugly position the shank portion of the blade within the conductor tube 14. In the case of a longer blade, as shown in FIG. 2, the innermost extremity 56 is laterally offset to project beyond the sleeve 54 and bear against the inner surface of the conductor tube 14. The conductor tube may be provided with indentations 57, 58 at longitudinally spaced intervals so that in positioning the shank end of the blade within the body 10 the surgeon can adjust the effective length of the blade which projects beyond the end 32 by sensing the engagement of the offset extremity 56 with the indentations 57 and 58. Additional indentations may be formed at spaced intervals as desired.

By virtue of the construction of the blade-receiving end 32 of the body 10, as illustrated in FIG. 6, a relatively short blade 16' may be attached in place of the blade 16 illustrated in FIG. 2. Thus, the blade 16' has a shank 17' covered with an insulating sleeve 54', the shank end 17' extended but a limited distance into the interior of the conductor tube 14.

In the fabrication of the switch assembly, it will be evident that the collars 24 can be separately assembled with attached contact rings 11 and 12. The assembled collars 24 are then positioned in a mold, not shown, with the conductor tube 14 and leads 18 and 19 positioned such that the lead 18 extends through the rearwardmost collar 24 and is electrically connected to the contact ring 11 while the lead 19 is connected to the contact ring 12. The body is then molded as a one-piece structure which will flow through and around the collars 24, and a temporary arbor is positioned centrally of the mold to define the desired interior configuration of the body wall and cavities 20, 21 with the inner contact rings 11 and 12 disposed in outer surrounding relation to the arbor, not shown. Once the body has solidified and cured, the temporary arbor is removed and the conductor tube 14 inserted into position as shown with the cable end portion 40 affixed, such as, with a suitable bonding agent to the end of the body in surrounding relation to the leads 41, 42 which project from the crimped end 46 of the conductor tube. Thus, in a one-step operation, the body can be integrated completely into unitary relation to the collars and connected leads 18 and 19. It will be evident that as a suitable alternative in the molding operation the conductor tube 14 can be employed in place of the temporary arbor in the molding operation but would require disposition of spacers on the tube for the formation of the cavities 20, 21. The spacers, not shown, would be suitably composed of a material which would disintegrate once the body material had at least partially solidified so as to permit removal of the spacer material from the blade-receiving end. As shown in FIG. 5, the cable-receiving end 30 may be given a generally polygonal configuration while the ribs 38 and 39 are given a circular configuration.

In accordance with conventional practice, the leads 18, 19 are connected along with the cable to an external power supply which will apply different power levels depending upon which of the switch contact elements 11 or 12 is depressed into engagement with the conductor tube 14. The positioning of the ribs 38, 39 is such that the surgeon can readily discern which of the switch elements is to be depressed for the desired power setting. In this relation, the body is preferably composed of an elastomeric material which possesses the necessary resiliency that it will normally retain the switch contact rings 11 and 12 in an open position but will permit depression of the elements into contact with the ring under positive hand or finger pressure. A particular advantage to be noted is that the switch is operational over a 360.degree. arc or, in other words, the entire circumference of the body so as to obviate removal of the blade when a change in blade position is called for. Typical materials which can be employed in the construction of the body are natural or synthetic rubber or rubber-like materials, such as, the Neoprene elastomers, vinyl or silicon materials. A preferred composition is a thermoplastic material sold by Shell Chemical Company under the trademark Kraton G2705. In this respect, when the blade is inserted through the blade-receiving end 32, the counterbore 50 will operate as a complete seal to prevent the intrusion or leakage of fluids into the interior of the blade which could otherwise cause malfunctioning of the contact elements.

It is therefore to be understood from the foregoing that various modifications and changes may be made in the construction and arrangement of parts as well as their method of fabrication without departing from the spirit and scope of the present invention as defined by the appended claims.