GB2322476A

GB2322476A - Pushbuttons

Info

Publication number: GB2322476A
Application number: GB9703272A
Authority: GB
Inventors: Alan Dewhurst
Original assignee: DEWHURST PLC
Current assignee: DEWHURST PLC
Priority date: 1997-02-17
Filing date: 1997-02-17
Publication date: 1998-08-26
Anticipated expiration: 2017-02-17
Also published as: GB9703272D0; GB2322476B

Abstract

A pushbutton 10 has a tubular body 20 which receives, for reciprocating movement therein, a pushbutton member 22. The body 20 is engaged with a base part 30 which is substantially U-shaped in cross section and carries a platform (36, Fig 6a) defining a planar support surface (38). The platform (36) carries at least two upstanding projections (40). A printed circuit board 42 carrying a switch mechanism is supported on the base part 30 by the projections (40) which pass through holes in the circuit board. The pushbutton member 22 is resiliently biased by one or more springs 62 which are located by the projections (40). One of the tubular body 20 and the base part 30 carries guide and engagement means (24, Fig 3) for engaging and guiding the pushbutton member 22.

Description

IMPROVEMENTS IN OR RELATING TO PUSHBUTTONS The present invention relates to pushbuttons and to a method of manufacturing a pushbutton.

Pushbutton assemblies are well known and are used in a number of environments. Commonly, a reciprocable pushbutton is used to actuate a switch which is arranged either internally or externally of the pushbutton, and it is helpful to a user that the actuation of the switch by the pushbutton is indicated.

This can be done, for example, by causing the actuation of the switch to illuminate the pushbutton in addition to performing its required function.

In some circumstances there is a restricted space for the pushbutton and there can be difficulties in fitting all of the components into that space. This is particularly the case where LEDs, or other illuminable means, are required to be incorporated within the pushbutton and/or where it is wished to manufacture the pushbutton as economically as possible.

The present invention seeks to address the problems of space and economy of manufacture for pushbuttons.

According to a first aspect of the present invention there is provided a pushbutton comprising a base part carrying at least two upwardly extending projections, a circuit board supported on said base part and located by said projections, a tubular pushbutton body, a pushbutton member mounted for reciprocation within said pushbutton body, and spring means biasing said pushbutton member outwardly of said pushbutton body, wherein said spring means extends between said base part and said pushbutton member and is located by said projections.

A pushbutton of an embodiment of the invention has a simple construction which can be made compact and which lends itself to economical manufacture. In this respect, the location of the spring means by projections of the base part facilitates the manufacturing process.

If required, a number of individual springs could be arranged to extend between the base part and the pushbutton member, with one end of each spring being located around one, or a number of, individual projections. However, in a preferred embodiment, a single, generally cylindrical, spring is provided and is located around all of the projections of the base part.

The number of projections carried on the base part can be chosen as required. Generally, however, where there is a single spring, it is preferred to have either three or four projections. In this respect, it is required to keep the number of projections small whilst providing a sufficient number to locate spring.

The tubular pushbutton body and the base part are fixed together by any appropriate means. However, it is preferred that the body and the base part be clipped or otherwise interengaged to faciiitate the manufacturing process.

Thus, one of the base part and the body may carry projections engageable within slots or recesses provided in the other of the body and base part.

In a preferred embodiment, the base part carries two upwardly extending clips arranged to engage in slots therefor in the body.

The base part supports a circuit board which is located by said projections. For example, the circuit board may be provided with slots, channels or holes in or through which the projections engage.

The circuit board may comprise, for example, part of a switch to be located within the pushbutton and/or may carry a switch. Additionally and/or alternatively, the circuit board may cany illuminable means for illuminating the pushbutton member.

In a preferred embodiment, the circuit board comprises a printed circuit board carrying switch means and illuminable means which are electrically connected thereto. The switch means incorporates a resiliently biased, reciprocable plunger, which is contactable and depressable by the pushbutton member.

In a preferred embodiment, the pushbutton member incorporates channels, holes or recesses to accommodate the illuminable means.

The pushbutton member is guided for reciprocating movement within the pushbutton body. The guidance may be provided by any suitable means.

Preferably, the guidance means also prevents rotation and/or pivotal movement of the pushbutton member relative to the body.

In one embodiment, the guidance means comprise projections on one of the body and pushbutton member engageable within channels in the other of the pushbutton member and body.

In an alternative embodiment, the guidance means comprise projections on one of the base part and the pushbutton member engaged within channels in the other of the base part and pushbutton member.

A pushbutton of an embodiment of the invention can be assembled easily, may be assembled automatically, and may be constructed without the use of screws.

According to a second aspect of the present invention there is provided a method of manufacturing a pushbutton as defined above.

The invention also extends to a method of manufacturing a pushbutton comprising locating spring means around projections on a base part, engaging the base part with a tubular body, and mounting a pushbutton member within said tubular body such that the spring means extends between the base part and the tubular body to resiliently bias said pushbutton member, one of the base part and the tubular body carrying guide and engagement means for engaging and guiding said pushbutton member.

In one method of the invention, the pushbutton member may be mounted within the tubular body after the tubular body has been engaged with the base part. In this case, therefore, the pushbutton member is mounted into the tubular body from its front.

Where it is preferred, or required, that the pushbutton member be mounted within the body from the rear, the pushbutton member may be located with respect to the base part and the spring means, and the tubular body thereafter engaged with the base part.

With assembly of the pushbutton in either of the sequences specified above, the pushbutton is built up sequentially from the base part in a manner which is very easy to achieve using automatic means.

In an alternative embodiment, the pushbutton member may be mounted within the tubular body before the tubular body is engaged on the base part.

Preferably, no screws or other fastenings are utilised in the construction.

Thus, the base part and tubular member are engaged by appropriate engagement means carried thereon. For example, the interengaging means may comprise projections carried on one of the base part and the tubular body, and corresponding slots or recesses carried on the other of the body and base part.

Similarly, the guide and engagement means for engaging the pushbutton member on the base part or the tubular body may be formed by interengaging means carried on the engaged elements.

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 side elevation of a pushbutton switch embodying the present invention, Figure 2 shows a longitudinal section through the pushbutton switch of Figure 1, Figure 3 shows a view, taken along line A-A of Figure 2, illustrating the engagement between a body and a pushbutton member of the pushbutton switch of Figure 2, Figure 4 shows a top view of a base part incorporated in the pushbutton switch of Figure 2 with a printed circuit board located thereon, Figure 5 shows a top view of the base part of Figure 4 with the printed circuit board omitted, Figure 6a shows a section taken along the line I-I of Figure 5, Figure 6b shows a section of the base plate taken along the line II-II of Figure 5, Figure 7 shows a section through one embodiment of a pushbutton member of the pushbutton switch of Figure 2, Figure 8 shows an underneath view of the pushbutton member of Figure 7, and Figure 9 shows an end elevation of the pushbutton member of Figure 7.

The pushbutton switch shown in the drawings has a circular crosssection. However, the invention is not limited to pushbuttons having a circular cross-section and the construction may have any required cross-section.

Similarly, in the embodiment of a pushbutton illustrated, the switch is located within the pushbutton itself. However, and if required, the switch may be located extemally of the pushbutton. Similarly, the pushbutton of the invention is shown with internal illuminable means. Such illuminable means may be provided externally of the pushbutton, if required, or omitted.

The drawings illustrate one embodiment of a pushbutton, which is configured as a pushbutton switch 10, and which is shown in Figure 1 when mounted on a face plate 12. In the embodiment in Figure 1, the pushbutton switch 10 is engaged with the face plate 12 by way of a rim 14 and a knurled ring 16. The knurled ring 16 has been screwed relative to a tubular body 20 of the pushbutton switch 10 to engage the back of the face plate 12 and to thereby hold the pushbutton switch in place in cooperation with the rim 14. In known manner, the rim 14 surrounds a cover or pressel plate 18 appropriately provided on a pushbutton member 22 of the pushbutton switch 10 as shown in Figure 2.

The manner in which the pushbutton switch 10 is mounted relative to the face plate 12 can be conventional and does not form part of the present invention. Similarly, the design of the cover or pressel plate 18 and its manner of incorporation within the pushbutton member 22 may be as required.

Conventionally, the cover plate 18 will be provided with appropriate indicia which may be illuminable.

The indicia carried by the cover plate will, preferably, be defined by slots cut into the cover plate. The pushbutton member 22 may be moulded onto the cover plate 18 so that the material of the pushbutton member is received within the slots. Conventionally the indicia carried by the cover plate are one or two letters or digits and may be illuminated by the illuminable means provided.

The structure of the pushbutton switch 10 is shown in Figure 2 from which it will be seen that the body 20 is tubular, and substantially cylindrical in the illustrated embodiment. The body 20 receives, for reciprocating movement therein, the substantially cylindrical pushbutton member 22. In this respect, the pushbutton member 22 is engaged with the body 20 by way of radially inwardly extending projections 24 (Figure 3) provided on the interior surface of the body 20 which engage within channels 26 provided within the exterior surface of the pushbutton member 22. As is apparent from Figure 9, the axial length of the channels 26 is restricted so that the channels 26 define the length of the reciprocal stroke of the pushbutton member. Furthermore, it will be apparent that the engagement of the projections 24 within the channels 26 prevents relative rotation between the pushbutton member 22 and the body 20.

The body 20 is engaged with a base part 30 whose structure is more clearly shown in Figures 5 and 6. As can be seen in these figures, the base part 30 is substantially U-shaped in cross-section having a base 34 and having two diametrically opposed clips 32 extending upwardly from the base 34. A plafform, indicated at 36, is carried by the base 34 and defines a generally planar support surface 38. The plafform 36 also carries four upstanding projections 40. As is apparent, the plafform 36 is shaped to have a central support area and peripheral regions, with the projections 40 upstanding from the peripheral regions thereof.

As indicated in Figure 4, a printed circuit board 42 is arranged on the base part 30. In this respect, the printed circuit board is provided with holes through which the projections 40 extend and protrude. What is more, the printed circuit board 42 carries a number of illuminable devices 44 thereon as well as a switch mechanism 46. The illuminable devices 44 may comprise any suitable means, such as light bulbs. In the embodiment illustrated, the devices 44 are LEDs.

As is apparent in Figure 2, the base part 30 is engaged with the body 20 by the engagement of its clips 32 within slots 50 formed in the body 20. In the engaged position, the printed circuit board 42 extends transversely across the pushbutton switch with a plunger 48 of the switch 46 extending upwardly for engagement with a base surface 52 of the pushbutton member 22.

Furthermore, and is apparent in Figure 8, the base of the pushbutton member 22 is provided with spaces as 54 for the receipt of the LEDs 44.

The pushbutton member 22 is resiliently mounted by way of a spring 62 extending between the base part 30 and the pushbutton member 22. As is apparent in Figure 2, a single cylindrically shaped spring 62 is provided and is arranged substantially coaxially with respect to the base part 30 about its circumference.

The pushbutton switch 10 shown in Figure 2 is particularly easy to assemble as there are no screws or other fixing means used. Thus, to assemble the pushbutton switch illustrated, the pre-wired printed circuit board 42 carrying the switch 46 and the LEDs 44 is located on the base part 30 by engaging the projections 40 of the base part within the holes provided in the circuit board 42. The resultant assembly can then be engaged with the body 20.

In the embodiment illustrated, the pushbutton member 22 is engaged within the body 20 such that the projections 24 of the body are engaged within the channels 26 of the pushbutton member. The spring 62 is located on the base part 30 around and supported by the projections 40 thereof. If then the base part 30 is engaged with the body by way of the engagement of its clips 32 in the slots 50, the construction is complete. In the completed pushbutton switch 10, the spring 62 urges the pushbutton member 22 forwardly. If the forward part of the body 20 is provided with a flange (not visible) against which the pushbutton member 22 is urged, the pushbutton switch 10 will be dustproof.

The completed construction has the advantage that the illuminable means, for example, the LEDs 44, are able to evenly illuminate the indicia in the cover plate 18.

As is apparent from Figures 7 and 9, in the embodiment illustrated, the pushbutton member 22 is made from two interengaged parts. These two parts are engaged together after their insertion into the body 20 from opposite ends thereof. This facilitates the engagement of the channels 26 of the pushbutton member with the radially inwardly projecting projections 24 of the body.

However, it is possible to make the pushbutton member in a single piece.

A construction of the pushbutton switch 10 in which the base part 30 is to be clipped to the body and which provides location for the spring lends itself to sequential assembly of the parts of the pushbutton and hence to the construction of the pushbutton by automatic means.

Embodiments of a pushbutton of the invention have the advantage that they are particularly robust and can be arranged to be vandal-resistant.

In the embodiment illustrated, guidance for the reciprocating movement of the pushbutton 22 is provided by the interengaging projections and channels of the pushbutton member and the body. However, it is possible, for example, to provide the guidance by appropriate interconnecting means on the base plate and on the pushbutton member. For example, upstanding projections on the base plate may be arranged to be received within axially extending channels in the pushbutton member.

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

Claims

1. A pushbutton comprising a base part carrying at least two upwardly extending projections, a circuit board supported on said base part and located by said projections, a tubular pushbutton body, a pushbutton member mounted for reciprocation within said pushbutton body, and spring means biasing said pushbutton member outwardly of said pushbutton body, wherein said spring means extends between said base part and said pushbutton member and is located by said projections.

2. A pushbutton as claimed in Claim 1, wherein a number of individual springs are arranged to extend between the base part and the pushbutton member, with one end of each spring being located around one, or a number of, individual projections.

3. A pushbutton as claimed in Claim 1, wherein a single, generally cylindrical, spring is provided and is located around all of the projections of the base part.

4. A pushbutton as claimed in any preceding claim, wherein the tubular pushbutton body and the base part are interengaged.

5. A pushbutton as claimed in Claim 4, wherein one of the base part and the body carries projections engageable within slots or recesses provided in the other of the body and base part.

6. A pushbutton as claimed in Claim 5, wherein the base part carries two upwardly extending clips arranged to engage in slots therefor in the body.

7. A pushbutton as claimed in any preceding claim, wherein the base part supports a circuit board which is located by said projections.

8. A pushbutton as claimed in Claim 7, wherein said circuit board comprises or carries a switch located within the pushbutton, and said circuit board carries illuminable means for illuminating the pushbutton member.

9. A pushbutton as claimed in Claim 8, wherein said circuit board comprises a printed circuit board carrying switch means and illuminable means which are electrically connected thereto, and wherein the switch means incorporates a resiliently biased, reciprocable plunger, which is contactable and depressable by the pushbutton member.

10. A pushbutton as claimed in Claim 8 or Claim 9, wherein the pushbutton member incorporates channels, holes or recesses to accommodate the illuminable means.

11. A pushbutton as claimed in any preceding claim, wherein the pushbutton member is guided for reciprocating movement within the pushbutton body by guidance means, and wherein the guidance means also prevent rotation and/or pivotal movement of the pushbutton member relative to the body.

12. A pushbutton as claimed in Claim 11, wherein the guidance means comprise projections on one of the body and pushbutton member engageable within channels in the other of the pushbutton member and body.

13. A pushbutton as claimed in Claim 11, wherein the guidance means comprise projections on one of the base part and the pushbutton member engaged within channels in the other of the base part and pushbutton member.

14. A method of manufacturing a pushbutton constructed and arranged as claimed in any preceding claim.

15. A method of manufacturing a pushbutton comprising locating spring means around projections on a base part, engaging the base part with a tubular body, and mounting a pushbutton member within said tubular body such that the spring means extends between the base part and the tubular body to resiliently bias said pushbutton member, one of the base part and the tubular body carrying guide and engagement means for engaging and guiding said pushbutton member.

16. A method as claimed in Claim 15, wherein the pushbutton member is mounted within the tubular body after the tubular body has been engaged with the base part, the pushbutton member being mounted into the tubular body from its front.

17. A method as claimed in Claim 15, wherein the pushbutton member is located with respect to the base part and the spring means, and the tubular body is thereafter engaged with the base part, the pushbutton member being mounted into the tubular body from the rear.

18. A pushbutton substantially as hereinbefore described with reference to the accompanying drawings.

19. A method of manufacturing a pushbutton substantially as hereinbefore described with reference to the accompanying drawings.