GB2278239A

GB2278239A - Pushbutton switch assembly

Info

Publication number: GB2278239A
Application number: GB9409640A
Authority: GB
Inventors: James Frederick Edwards
Original assignee: DEWHURST PLC
Current assignee: DEWHURST PLC
Priority date: 1993-05-19
Filing date: 1994-05-13
Publication date: 1994-11-23
Anticipated expiration: 2014-05-13
Also published as: CA2123819A1; GB9409640D0; GB2278239B; GB9409639D0; GB2278238A; GB9310265D0; GB2278238B

Description

2278239 IMPROVEMENTS IN OR RELATING TO PUSHBUTTON SWITCHES The present

invention relates to pushbutton switches.

Pushbutton switches, are provided in a variety of locations, such as in lifts. It is frequently required to provide illumination thereto, for example, to indicate that the switch has been operated or to facilitate use of the pushbutton. It is known to illuminate such switches by providing an illuminated halo surrounding the pushbutton. A construction of a pushbutton switch having such a halo effect is described in our earlier UK Patent No. 1456391.

The switch described in our British Patent No. 1456391 has been in use for about twenty years and functions extremely well. However, the switch is somewhat bulky and, especially as it is generally required to provide more than one such switch in a lift, for example, it would be desirable to provide a more compact arrangement.

According to the present invention there is provided an electrical pushbutton switch assembly comprising a housing having a base and an upstanding peripheral wall, a pair of electrical switches supported generally opposite to each other on said peripheral wall and each having an upstanding, reciprocal, resiliently mounted, switching member, and a pushbutton member supported within said peripheral wall for reciprocable movement relative to said housing, said pushbutton member having two switching projections each arranged in contact with a respective switching member such that reciprocable movement of said pushbutton member causes reciprocation of said switching members, wherein, the housing and the pushbutton member are configured such that the reciprocable movement of the pushbutton member is within said housing, and such that the overall height of the housing is generally substantially the same as the height of each said switch including its switching member.

In the known switch described in British Patent No. 1456391 the individual switches are supported on the housing and the pushbutton member is guided for reciprocating movement in an extension of the housing located above the switches. As the movement of the pushbutton member needs to be over a distance substantially the same as that of the full throw of the switch member of each switch, the overall height of the pushbutton switch assembly is substantially twice the height of each switch. This means that even if the size of the individual switches is reduced, the need to provide for the full movement of the pushbutton member keeps the relative height of the switch assembly large.

With the present invention, the height of the switch housing is kept substantially the same as the height of each individual switch. If then the individual switches are made as small as practicable, the switch assembly becomes much more compact in size.

In the known switch assembly, the pushbutton member is guided for reciprocable movement around its entire periphery. In an electrical pushbutton switch assembly of the invention, reciprocation of the pushbutton member within the housing, between, rather than above the switches, is enabled by providing for guiding of the reciprocal movement of the pushbutton member at two opposed areas thereof only.

In a preferred embodiment, a pair of cooperating guide means for guiding the reciprocal movement of said pushbutton member are provided, each guide means comprising cooperating guide surfaces on said pushbutton member and on 1 said peripheral wall, and the guide means of the pair are arranged generally opposed to each other, wherein an axis extending between said pair of switches is arranged at an angle to an axis extending between said pair of guide means.

It is important that the reciprocal movement of the pushbutton member is guided such that twisting thereof is prevented. In this respect said cooperating guide surfaces preferably depend relative to said pushbutton member, and preferably comprise at least one projection carried by a respective one of the pushbutton member and the peripheral wall and received in a corresponding recess provided on the other of the peripheral wall and the pushbutton member. In a particularly preferred embodiment, each said guide means comprises at least two longitudinally extending projections received in corresponding longitudinally extending recesses.

In a particularly preferred embodiment, each said guide means comprises a depending substantially U-shaped guide channel on said pushbutton member, said guide channel having a base and two upstanding walls defining said longitudinally extending projections, and wherein said peripheral wall is provided with two corresponding longitudinally extending recesses into which respective ones of said projections are received. Preferably, surfaces defining, or defined by, said recesses contact the base of said channel to provide additional guidance.

In a preferred embodiment, said pushbutton member comprises a substantially rectangular carrier plate having guide channels on two opposed sides thereof, and depending from the plate. Said carrier plates may also support said switching projections which extend from the other two opposed sides of the carrier plate. Preferably, each said switching projection comprises a flange extending substantially in the plane of the carrier plate along one side thereof, one end of each said flange being arranged to contact a respective switching member, and the other end of each said flange being arranged to contact a respective spring supported between the carrier plate and the housing.

The springs located between the carrier plate and the housing comprise bias springs to bias the pushbutton member to its initial, non depressed position. The arrangement enables each bias spring to be located to one side of a respective switching member. This enables a more compact construction as compared to the known switches in which the bias springs are located above the switching members.

The pushbutton member may comprise a carrier plate formed in one piece with the pushbutton pressel plate. However, it is preferred that the pushbutton member comprise a cover member interengaged with a carrier.

- Preferably, said pushbutton member comprises a carrier, and a cover member interengaged with said carrier, wherein said carrier comprises a plate, and interengaging means provided on said plate, wherein said cover member comprises a body member having an external surface, an opaque cover plate fixed to said external surface of said body member, and interengaging means cooperable with those of said carrier to retain said cover member on said carrier, and wherein said carrier plate and said body member are formed of a transparent or translucent material.

In an embodiment, the plate of said carrier has at least one aperture extending therethrough around which the interengaging means on said plate are provided. In this case, said cover member is retained on said carrier to extend over said aperture or apertures.

1 It is preferred that the carrier plate and the body member both be made of a polycarbonate plastics material.

In a preferred embodiment, the body member comprises a substantially planar wall on which said external surface is defined and a peripheral skirt depending from said planar wall. The interengaging means carried by said body member comprise resilient projections projecting from or formed within said peripheral skirt. The cooperable interengaging means of said carrier plate preferably comprise slots extending through said carrier plate into which a corresponding resilient projection may be received. Preferably, each said resilient projection is provided with a flange arrange to clip onto or engage with part of the respective slot in said carrier plate to retain the cover member thereon.

Preferably, the cooperable interengaging means are releasable.

Preferably the interengaging means are arranged so that the cover member may be retained on said carrier in a selected one of at least two positions. For example, two oppositely arranged resilient projections may be provided on said cover member whereas two pairs of opposed spaced slots are provided in said carrier plate. The projections of the cover member may be engaged with a selected one of the pairs of slots and thereby engaged in a selected one of two orientations.

Preferably, the carrier plate is provided with a single aperture which is substantially square in shape. The cover member is similarly substantially square in shape.

To facilitate the construction of the pushbutton switch assembly of the invention, the housing may be made in two parts, the first part being a substantially planar base on opposite sides of which said switches are mounted. Preferably, each said switch has a respective switch housing, at least part of which is moulded in one piece with said base. Preferably, the switch housings are generally on opposite sides of a centre line of said base.

The housing also preferably comprises a body member having a peripheral wall for substantially defining the upstanding peripheral wall of said housing. Said body member has a central aperture, and appropriate webs and apertures connect the central aperture thereof to the peripheral wall. The webs and apertures are arranged and configured to engage with the base, to enable the switching members to extend upwardly from the base to within the completed housing, and to form the respective guide surfaces on the upstanding peripheral wall. The base and body member defining the housing are each designed to make their moulding simple. Preferably, the base and the body member are moulded in a polycarbonate plastics material, which is thermally stable and strong.

Each said switch is a substantially conventional construction normally open or normally closed, electrical switch operable by way of a switch member in the form of a spring mounted plunger. However, the switches are designed to be as small as possible. In this respect the currents applied to such switches are generally small and to avoid problems with contaminants it may be required to incorporate silver or gold alloy on their contacts. This becomes economically possible if the switches are made small.

Preferably the base of the housing carries illuminating means.

The illuminating means may be configured and supported as required. For example, the illuminating means may comprise a light bulb supported by a bulb holder, the bulb being connected to electrical terminals supported by the housing.

In an alternative embodiment, the illuminating means may comprise a number of LEDs appropriately mounted and connected by way of an electrical circuit to electrical terminals. In a preferred embodiment, the LEDs may be mounted and supported on a printed circuit board.

Preferably, the bulb holder and the printed circuit board are arranged to be interchangeably mounted in said housing.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 shows a front view of a pushbutton switch assembly of the present invention, Figure 2 shows an underneath view of the assembly of Figure 1, Figure 3 shows a section of the switch assembly of Figures 1 and 2 taken along the line BB of Figure 2, Figure 4 shows a section of the switch assembly of Figures 1 and 2 taken along the line AA of Figure 2, and Figure 5 shows of plan view from underneath of a carrier plate of a pushbutton member of the switch assembly.

The electrical pushbutton switch assembly shown in the drawings is specifically designed for use in lifts but, of course, may be used in any situations where pushbutton operation is required. The particular switch assembly illustrated is illuminable. As compared with prior art switch assemblies, the switch assembly described herein is more shallow and considerably more compact. Furthermore, the pushbutton member of the switch assembly described herein comprises a standardised cover member carrying selected indicia which may be fitted into the switch assembly at the last stage of manufacture. The cover member may be selectively oriented and may be selected to carry the required indicia, or be plain, to suit the location chosen for the pushbutton switch assembly.

Figure 1 illustrates a pushbutton switch assembly mounted in situ. In this respect, the switch assembly has a housing 2 which in use is mounted behind a door or panel skin 4 (not visible in Figure 1) by way of mounting screws 6. The switch assembly is mounted so that a cover or pressel plate 8 of a reciprocable cover or pressel member 10 is visible and accessible to a user. The pressel plate 8 is surrounded by a halo of translucent material provided by the pressel member 10 and by a carrier 12 therefor. In use, the switch assembly is illuminated so that a halo of illumination surrounds the pressel plate 8. In Figure 1, the pressel plate 8 is plain. However, illuminable indicia can be provided on the pressel plate 8 if required.

As can be seen in Figures 3 and 4, the pressel member 10 comprises a body member 14 which is preferably made of a translucent polycarbonate plastics material. The body member 14 is substantially square in shape and has a substantially square, substantially planar base wall 16 from which an upstanding, peripheral skirt 18 depends. On the front, external surface of the base wall 16 the pressel plate 8 is fixed. In known manner the body member 14 is fixed to the pressel plate 8 during moulding of the body member. If the pressel member 10 is to carry indicia, appropriate cutouts are made in the pressel plate 8 before -g- the m. oulding operation. The translucent plastics material then fills the cutouts in the plate 8 in known manner. Preferably, the pressel plate 8 is made of stainless steel.

The pressel member 10 is engaged with the carrier 12.

To facilitate this, on two sides the body member 14 of the pressel member 10 is formed to provide resilient clips 20.

As can be seen in Figure 3, each clip 20 is a resilient projection projecting from and formed within said peripheral skirt 18. Each projection 20 is provided with a flange 22 for engagement with a respective slot in the carrier 12.

The carrier 12 is also preferably made of a translucent polycarbonate plastics material and is arranged to guide the body member 14 for reciprocable movement within the switch housing 2 and also to enable the halo illumination around the pressel plate 8. Furthermore, it is the carrier 12 which switches the individual switches within the switch assembly.

A plan view from underneath of the carrier 12 is shown in Figure 5. The carrier 12 comprises a substantially square carrier plate 24. This carrier plate has an external upstanding rim 26 as can be seen in Figure 4.

Centrally of the plate 24 there is provided a substantially square aperture 28 and adjacent each side of the aperture 28 there is provided a respective slot 30. These slots 30 define interengaging means for cooperating with the clips 20 on the body member 14. In this respect, the pressel member 10 is generally provided with two opposed clips 20.

It will therefore be appreciated that the pressel member 10 may be oriented selectively by engaging the clips 20 in a selected one of the two pairs of opposed slots 30. When the pressel member 10 is engaged with the carrier plate 24, by way of the clips 20, part of the translucent body member 14, and the rim 26 of the carrier plate 24, extend outwardly of, and surround the periphery of the pressel plate 8 as can be seen in Figure 4. This provides, in use, and in known manner, an illuminable halo around the pressel plate 8.

The carrier plate 24 is guided for reciprocating movement within the housing 2 by guide means 34 provided on two opposed surfaces of the carrier plate 24. As indicated in Figures 2, each guide means 34 comprises an elongate channel member depending from the carrier plate 24 and having a base surface formed between two upstanding walls 36 defining longitudinally extending projections. The projections 36 are received in corresponding longitudinally extending recesses (not visible) in the housing 2 to guide the carrier 12 for reciprocal movement along the longitudinal axis of the switch assembly.

On its other two sides, the carrier plate 24 is provided with switching projections 40. Each switching projection 40 is formed by a flange extending substantially in the plane of the carrier plate 24, and extending along the respective side of the carrier plate 24. Each said flange carries a protuberance 42 for contacting a plunger of an individual switch and a projection 44 for locating a bias spring 62 (Figure 4). In this respect, in known manner depression of the pressel member 10 is arranged to cause depression of the carrier 12 whereby plungers of the individual switches carried by the housing 2 will be depressed, by way of the protuberances 42. When the pressure is released, bias springs located by the projections 44 will push the carrier 12, and hence the pressel member 10 to the outward rest position, the plungers also being biassed to be returned by spring force.

One of the individual switches 50, which is a normally closed switch, of the pushbutton switch assembly, can be seen in Figure 3. The switch 50 is a substantially conventional construction and comprises a moveable contact 52 normally held against individual fixed contacts 54 by way of a spring 56. The moveable contact 52 is connected to the spring 56 and also to a plunger 58. The plunger 58, which is the switching member of the switch 50, projects upwardly to contact the underside of one of the protuberances 42 of the carrier 12. It will be appreciated that depression of the plunger 58 will open the contacts 52, 54 and move the moveable contact 52 into contact with a lower contact 60.

The switch assembly shown in the drawings is particularly shallow and compact. In this respect the overall height of the switch assembly is generally substantially the same as the overall height of an individual switch 50 when its plunger 58 is in its upper rest position. All of the necessary reciprocating movement of the carrier 12 takes place within the housing 2 and this leads to the compact construction illustrated.

The compact construction is also enabled because the carrier 12 is guided for reciprocating movement along two only of its sides. This means that no guiding function has to be provided on sides of the carrier 12 which contact the switch plunger 58 and the bias springs 62. Guidance can be provided at two opposed areas of the carrier 12 only because of the provision of the channels 34, the longitudinally extending walls 36 of which are each received within a respective recess in the wall of the housing 2. These recesses extend over substantially the entire height of the housing 2 so that the carrier 12 remains guided irrespective of its location along the height of the housing 2. Preferably, the recesses are defined between projecting surfaces of the housing 2 which are also arranged to abut against the base of the respective channel 34. This ensures that there is no ability for twist to be introduced into the reciprocating movement of the carrier 12.

The manner in which the housing 2 is constructed also enables it to be made compact. In this respect the housing 2 is preferably moulded from a polycarbonate plastics material and is moulded in two parts. The first part is a substantially planar base 70 which is integrally formed with part of a housing 72 for each of the two switches 50. In this respect, the switch housings 72 each have a clipped on side wall 74 and are generally rectangular. The housings each project upwardly of the base 70 on two sides thereof.

In its central region the base 70 holds a bulb 80 carried on a bulb holder 82 for which appropriate electrical terminals 84 are also provided. The bulb 80 extends substantially centrally within the housing 2 and provides illumination directed at the underside of the base wall 16 of the body member 14 of the pressel member 10. In the embodiment illustrated, the bulb holder 82 also carries a reflector 90 to surround the bulb 80 and direct the light. If required, the bulb holder 82 with its bulb 80 and terminals 84 may be replaced by an illumination printed circuit board carrying LEDs and appropriate electrical terminals.

To complete the formation of the housing 2 the base 70 is engaged with a moulded body 100. The body 100 is also preferably moulded from a polycarbonate plastics material. This body 100 is a generally rectangular hollow member having a perimeter rim. on two sides the interior surface of the perimeter rim is formed with the necessary longitudinally extending recesses for receiving the walls 36 of the channel members 34 of the carrier 12 to provide the necessary guidance. The body 100 is also formed with bores or apertures through which the plungers 58 extend. A central bore is also provided through which the bulb 80 projects. The body 100 is also formed with locating points for the bias springs 62. The body 100 and the base 70 are interengaged such that the perimeter rim of the body 100 and the switch housing 72 together define a generally upstanding peripheral wall of the housing 2, and a front opening in which the pressel member 10 is mounted.

It will be appreciated that the switch assembly having two plunger operated switches controlled by the depression of a pressel member 10 is substantially conventional in the functioning components provided and in its manner of operation and so the operation of the switch assembly will not be further described.

It will be appreciated that modifications in and variations to the embodiments specifically described and illustrated may be made within the scope of this application.

Claims

1. An electrical pushbutton switch assembly comprising a housing having a base and an upstanding peripheral wall, a pair of electrical switches supported generally opposite to each other on said peripheral wall and each having an upstanding, reciprocal, resiliently mounted, switching member, and a pushbutton member supported within said peripheral wall for reciprocable movement relative to said housing, said pushbutton member having two switching projections each arranged in contact with a respective switching member such that reciprocable movement of said pushbutton member causes reciprocation of said switching members, wherein, the housing and the pushbutton member are configured such that the reciprocable movement of the pushbutton member is within said housing, and such that the overall height of the housing is generally substantially the same as the height of each said switch including its switching member.

2. A switch assembly as claimed in Claim 1, wherein the reciprocal movement of the pushbutton member is guided at two opposed areas thereof only.

3. A switch assembly as claimed in Claim 2, wherein a pair of cooperating guide means for guiding the reciprocal movement of said pushbutton member are provided, each guide means comprising cooperating guide surfaces on said pushbutton member and on said peripheral wall.

4. A switch assembly as claimed in Claim 3, wherein the guide means of the pair of cooperating guide means are arranged generally opposed to each other, and wherein an axis extending between said pair of switches is arranged at an angle to an axis extending between said pair of cooperating guide means.

1

5. A switch assembly as claimed in Claim 3 or Claim 4, wherein said cooperating guide surfaces depend relative to said pushbutton member, and comprise at least one projection carried by a respective one of the pushbutton member and the peripheral wall and received in a corresponding recess provided on the other of the peripheral wall and the pushbutton member.

6. A switch assembly as claimed in Claim 5, wherein each said guide means comprises at least two longitudinally extending projections received in corresponding longitudinally extending recesses.

7. A switch assembly as claimed in any of Claims 3 to 6, wherein each said guide means comprises a depending substantially U-shaped guide channel on said pushbutton member, said guide channel having a base and two upstanding walls defining longitudinally extending projections, and wherein said peripheral wall is provided with two corresponding longitudinally extending recesses into which respective ones of said projections are received.

8. A switch assembly as claimed in Claim 7, wherein said pushbutton member comprises a substantially rectangular carrier plate having guide channels on two opposed sides thereof, and depending from the plate.

9. A switch assembly as claimed in Claim 8, wherein said carrier plate supports said switching projections which extend from the other two opposed sides of the carrier plate, and wherein each said switching projection comprises a flange extending substantially in the plane of the carrier plate along one side thereof, one end of each said flange being arranged to contact a respective switching member, and the other end of each said flange being arranged to contact a respective spring supported between the carrier plate and the housing.

10. A switch assembly as claimed in any preceding claim, wherein said pushbutton member comprises a carrier, and a cover member interengaged with said carrier, wherein said carrier comprises a plate, and interengaging means provided on said plate, wherein said cover member comprises a body member having an external surface, an opaque cover plate fixed to said external surface of said body member, and interengaging means cooperable with those of said carrier to retain said cover member on said carrier, and wherein said carrier plate and said body member are formed of a transparent or translucent material.

11. A switch assembly as claimed in Claim 10, wherein the carrier plate and the body member are both made of a polycarbonate plastics material.

12. A switch assembly as claimed in Claim 10 or Claim 11, wherein the body member comprises a substantially planar wall on which said external surface is defined and a peripheral skirt depending from said planar wall, the interengaging means carried by said body member comprise resilient projections projecting from or formed within said peripheral skirt, and the cooperable interengaging means of said carrier plate comprises slots extending through said carrier plate into which a corresponding resilient projection may be received.

13. A switch assembly as claimed in Claim 12, wherein each said resilient projection is provided with a flange arranged to clip onto or engage with part of the respective slot in said carrier plate to retain the cover member thereon.

14. A switch assembly as claimed in any of Claims 10 to ii 13, wherein the interengaging means are arranged so that the cover member may be retained on said carrier in a selected one of at least two positions.

15. A switch assembly as claimed in any preceding claim, wherein said housing is made in two parts, the first part being a substantially planar base on opposite sides of which said switches are mounted, and the second part comprising a body member having a peripheral wall for substantially defining the upstanding peripheral wall of said housing.

16. A switch assembly as claimed in Claim 15, wherein said body member has a central aperture, and appropriate webs and apertures connect the central aperture thereof to the peripheral wall, and wherein the webs and apertures are arranged and configured to engage with the base, to enable the switching members to extend upwardly from the base to within the completed housing, and to form the respective guide surfaces on the upstanding peripheral wall.

17. A switch assembly as claimed in Claim 15 or Claim 16, wherein the base of the housing carries illuminating means.

18. A switch assembly as claimed in Claim 17, wherein the illuminating means comprises a light bulb supported by a bulb holder, the bulb being connected to electrical terminals supported by the housing.

19. A switch assembly as claimed in Claim 17, wherein the illuminating means comprises a: number of LEDs mounted and supported on a printed circuit board and connected by way of an electrical circuit to electrical terminals.

20. An electrical pushbutton switch assembly substantially as hereinbefore described with reference to the accompanying drawings.