GB2094555A - Electrical switch - Google Patents

Abstract

A switch comprises a casing (1), which can be used as a handle for an electro-surgical instrument, and a printed circuit type switch element (6) comprising a laminate of a conductive material such as copper, and a flexible plastics material such as polyamide. The laminate is folded on itself at a fold-line to provide two portions, one of which carries a common conductor area (10) and the other of which carries a switch contact member or members (11), which are spaced by an insulating separator (17, Fig. 5, not shown). The switch contact member(s) (11) can be brought into contact with the common conductor area (10) by finger pressure exerted on push buttons (5). A compressible washer (24, Fig. 5) may be provided to ensure positive separation of the area (10) and member(s) (11) after removal of pressure or the element (6) itself may be sufficiently resilient to enable separation. A chuck (4) may be provided to grip the electro-surgical instrument. <IMAGE>

Description

SPECIFICATION Switches This invention relates to electrical switches.

Electrosurgical equipment is used in operating theatres for the cutting and coagulation of body tissue and requires means for switching the output on and off under the control of the surgeon. This is normally accomplished either by foot operated switches or by control buttons on an electrode holder held in the hand of the surgeon.

Such controls are well established and available for most types of electrosurgical equipment.

It is an object of the present invention to provide an improved electrical switch for on/off control of such equipment which is inexpensive to manufacture.

According to the present invention, there is provided such a switch which comprises a rigid casing which is adapted to be held in the hand, to receive an electrosurgical instrument, and to be connected to an electrical supply source; a switch element inside the casing operable to control the electrical supply from the source to the instrument; and at least one switch operating member operable to control the switch element; wherein the switch element is a flexible strip which is a laminate of a conductive material and an insulative material, the strip being folded on itself to provide two portions, the conductive material of one portion of the laminate providing a common conductor area connected to the source of supply and the conductive material of the outer portion of the laminate providing at least one contact area facing the common conductor area and connected to the instrument, a separator of insulating material having at least one aperture therein being arranged between the two portions and the arrangement being such that the contact area or areas, can be brought into contact with the common conductor area through the aperture or apertures by pressure on the switch operating member or members.

To ensure positive separation of the contact surfaces a resilient washer preferably forms the periphery to the or each aperture in the separator.

This washer may be made of silicone or similar material.

A switch constructed according to the invention is operable by the pressure from the fingers of a surgeon using the device to perform an electrosurgical operation. Printed circuit techniques may be used in the production of the flexible strip of the switch device so that the device is inexpensive to manufacture. The device can be sterilised in a steam autoclave if the materials used to construct the flexible strip are suitably chosen.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a sectional view showing a switch constructed according to the invention; Figure 2 illustrates the layout of a switch element in an open condition, Figure 3 illustrates a separator forming part of the switch, Figure 4 illustrates an alternative switch element layout to that shown in Figure 2, and Figure 5 illustrates a cross-section through a portion of an assembled switch incorporating the element shown in Figure 4.

In the illustrated embodiment of the invention a switch for use in controlling an electro-surgical apparatus comprises a rigid casing 1 made of a suitable plastics material, conveniently by injection moulding. A screw cap 2 is fitted on a front end of the casing 1 and has a front opening 3 through which a portion of an electro-surgical instrument can be inserted and engaged with a gripping device such as a retaining chuck 4 or collet within the casing.

The casing 1 is intended to be held in the hand of the surgeon performing an electro-surgical operation. The electrical operation of the surgical instrument is controlled by operation of switch push-buttons 5 which are accessible from outside the casing and can be depressed to operate the switch by pressure of the fingers of the surgeon holding the casing 1. The switch buttons 5 control; a switch element 6 now to be described with reference to Figures 2 and 3 of the drawings.

The switch element 6 is resilient and is a laminate of a conductive material, e.g. copper, and a plastics material such as polyamide. The laminated strip is sufficiently flexible to be folded about a fold line indicated by the broken lines 7 to produce two switch portions as illustrated in Figure 1. The switch element 6 is supported in the casing 1 in the folded condition by a support member 8 and a backplate 9.

In order to form suitable conductive and contact areas in the switch element, the copper portion of the laminate is masked off and the laminate is placed in a suitable etching solution to remove the unmasked portions of the copper. This leaves a common conductor area 10 on one portions of the laminate, contact pads 11 and connector leads 12. The common conductor area has an extension providing a connector 13 by which the device can be directly connected to an electrode of an electro-surgical device. A flexible lead 14 leading to an electro-surgical generator of the device has a conductor through which output current can pass connected to a conductive pad 1 6. Two further conductors are connected to pads 19 and 20 to convey switching currents.The plastics layer of the laminate is provided with an aperture or "window" 15 in such a position that when the element is folded about the fold-line, pads 16, 19 and 20 pass through the window 1 5 to enable connection of an extended cable by soldering. When the element is folded in this way the switch contact pads 11 are registered with the common conductor area 10. The contact members 11 and the common conductor area 10 are separated by a separator layer or "wafer" 17 illustrated in Figure 3. This separator 17 is bonded to the element 6 and has two apertures 18 so positioned that contact members 11 register with the contact member 10 without contact being made. A window 22 in the separator 17 provides access through window 15 to pads 1 6, 19 and 20 for soldering.

When the element is assembled in the casing 1, the contact members 11 are registered with the buttons 5. If these buttons are pressed, as by the fingers of the surgeon, the contact members 11 will make contact with the common conductor area 10 through the apertures 18. When pressure is released, the flexibility and resilience of the element will enable the element to resume its normal condition so that contact will be broken.

When the switch element is fitted in the casing, a portion of the copper conductor 13 will make contact with the chuck 4 as indicated at 21 in Figure 1.

In the alternative switch element b layout shown in Figure 4, the laminate strip is folded along two longitudinally extending fold lines 7a and 7b as indicated. Otherwise this element is similar to that shown in Figure 2.

The laminate is divided by the two fold lines 7a, 7b into three strip portions 6a, 6b and 6c of equal width. Strip 6a has the common conductor area 10 with connector 13 and five windows 1 5 respectively provided to reveal the pads 16, 19 and 20 on strip 6b when the element is folded on itself. Additional two windows 26 are provided to reveal a diode pad 27 also on the strip 6b. Contact members 11 connected to pads 19 and 20 are also provided on strip 6b for folding into register with conductor area 10.

Strips 6b is recessed in the region of the element 6 neighbouring connector 13 so that connector 13 is available to make contact with the chuck 4.

Strip 6c does not carry any conductive material and is therefore entirely composed of insulative material. When the element 6 of Figure 4 is folded, strip 6c folds around the strip 6a. Strip 6c is therefore provided with five windows 25 which register with windows 1 5 and 26 to allow access to pads 16, 19 and 20 and diode pad 27 for soldering.

As in the previous embodiment, a separator 17 having two apertures 18 and window 22 as shown in Figure 3 is located between strips 6a and 6b on folding. The periphery of each aperture 18 is provided with a compressible washer 24 as indicated in Figure 5. This washer 24 is provided to ensure positive separation of the contact surfaces.

Figure 5 shows a cross section through a portion of the switch when assembled, and intersects an aperture 18 of the separator 17.

Claims (9)

1. An electrical switch comprising a casing which is adapted to be held in the.hand, to receive an electro-surgical instrument, and to be connected to an electrical supply source; a switch element inside the casing and operable to control the electrical supply from the source to the instrument; and at least one switch operating member operable to control the switch; wherein the switch element is a flexible strip which is a laminate of a conductive material and an insulative material, the strip being folded onto itself to provide two portions, the conductive material of one portion of the laminate providing a common conductor area connected to the source of supply and the conductive material of the other portion of the laminate providing at least one contact area facing the common conductor area and connected to the instrument, a separator of insulative material having at least one aperture therein being arranged between the two portions, and the arrangement being such that the contact area or areas can be brought into contact with the common conductor area by pressure through the aperture or apertures on the switch operating member or members.

2. A switch as claimed in claim 1 wherein the common conductor area and the at least one contact area are provided at opposite ends of the strip which is folded transversely.

3. A switch as claimed in claim 1 wherein the common conductor area and the at least one contact area are provided neighbouring one another at one end of the strip which is folded longitudinally.

4. A switch as claimed in any one of claims 1 to 3 wherein one or more openings is or are provided in said one portion of the strip through which electrical connection of the or each contact area with the electrical supply source for current supply to the switch can be made.

5. A switch as claimed in any preceding claim, wherein an opening is provided in said one portion through which electrical connection of said common conductor area and a conductorfor conveying current away from said switch can be made.

6. A switch as claimed in any preceding claim wherein one end of said one portion extends beyond that of said second portion and has a connector thereon for electrical connection with the electro-surgical instrument.

7. A switch as claimed in any preceding claim wherein said flexible strip comprises a third portion composed entirely of insulative material which extends from said other portion along a fold line, said strip being folded such that said one portion is located between said other and said third portions.

8. A switch as claimed in any preceding claim wherein the or each aperture in the separator is defined by an annular member of resilient material.

9. An electrical switch substantially as herein described with reference to Figures 1 to 3 with or without reference to Figures 4 or 5.