GB2305888A

GB2305888A - A method of forming indicators and push-button members by locating an element thereof inside a mould

Info

Publication number: GB2305888A
Application number: GB9620529A
Authority: GB
Inventors: Arthur David Young
Original assignee: DEWHURST PLC
Current assignee: DEWHURST PLC
Priority date: 1995-10-02
Filing date: 1996-10-02
Publication date: 1997-04-23
Anticipated expiration: 2016-10-02
Also published as: GB9520072D0; GB2305888B; GB9620529D0; HK1011637A1

Abstract

During the formation of an indicator or push-button assembly, a locating body (30) is engaged on the rear surface of a front plate (16), for example, by engaging on weldstuds (26, 28). This locating body (30) carries an outwardly extending tab (38). The front plate (16) is then located in a mould by engaging the tab (38) in a recess therefor and a body member (40) is moulded thereon. Because the front plate is accurately located in the mould, the relative orientation between the front plate and the mould body is similarly accurate. This means, for example, that when the resultant push-button member is engaged in a housing, it is ensured that any indicia (18, 20) carried thereon are upright.

Description

A METHOD OF FORMING INDICATORS AND PUSH-BUTTON MEMBERS The present invention relates to an indicator or pushbutton member, and to a method of forming an indicator or push-button member.

Push-button switches are commonly provided in situations in which the push-button member is also required to display some form of information. For example, pushbutton switches may be provided as part of a lift system for use to call a lift and/or to select a particular destination for the lift. Such push-buttons may be provided with indicia in the form of letters or numerals on the front face of the push-button, for example, formed by projections on the front face or by one or more apertures extending through the front face.

Similarly, indicators are commonly provided in the form of a front plate member having indicia on the front face thereof. Such indicators may be provided at a lift entrance/exit location, for example, to indicate the particular location of the lift at any given time.

Of course, where the indicator or push-button member carries indicia it is particularly important that the indicia be correctly orientated in an upright position.

This, in its turn, means that the indicator or push-button member must be correctly orientated with respect to any housing in which it is mounted. For indicators or pushbutton members having a front plate mounted on a body member, this also means that the front plate must be correctly aligned with reference to the body member as it is commonly the body member which determines the orientation of the indicator or push-button member within a housing.

Where the front plate of the indicator or push-button member is circular specific measures have to be taken to ensure that any indicia on the front plate are accurately aligned with respect to the body member. Generally, the body member is moulded on to the front plate and, in the past, the correct alignment has been achieved, for example, by providing flats on the periphery of the front plate and/or providing recesses therein. These flats or recesses are used to orientate the front plate relative to a mould cavity. However, such orientating means have the considerable disadvantage that they deform the shape of the front plate member and thereby spoil its aesthetic appearance.

The present invention seeks to provide a method of forming indicators and push-button members which has advantages over known methods.

In accordance with a first aspect of the present invention there is provided a method of forming an indicator or push-button member comprising a front plate member mounted on a body member, the method comprising the steps of providing on said front plate member a locating member extending outwardly of said front plate member, locating the front plate member in a mould in a required orientation by engaging said locating member with a cooperating part of said mould, and introducing molten material into the mould to form the body member on the front plate.

The locating member extending outwardly of the front plate member enables the accurate location of the front plate member in a mould but without requiring any deformation of the front plate member itself. Thus, the indicator or push-button member removed from the mould has accurately aligned front plate and body members.

For most applications, the locating member will be removed from the indicator or push-button member after the moulding has been completed. However, there may be occasions where it is advantageous to retain the locating member and use it, for example, to locate the indicator or push-button member in a housing.

Preferably, said locating member is provided on a locating body carried by said front plate. For example, the method may further comprise the step of engaging the locating body on said front plate member.

In a preferred embodiment, said locating body is releasably engaged on said front plate member.

In providing for releasable engagement of the locating body, the invention is particularly advantageous in that if, for some reason, the locating body becomes damaged or dislodged, it can simply be removed from engagement with the front plate member, and replaced by another locating body.

In a preferred embodiment, said locating body is engaged with protrusions carried by said front plate member. For example, the protrusions may extend from the underside of said front plate member and act to key the front plate member to the material of the body member.

Engagement of the locating body on the protrusions may be facilitated, for example, by making the locating body resiliently deformable.

The protrusions, for example, may be projecting weldstuds or other projections provided to key the material of the body member to the front plate member during the moulding process. It is, of course, advantageous to use these existing protrusions to engage the locating body as no additional manufacturing steps have to be undertaken to provide the engagement for the locating body. In addition, the weldstuds may also be used to facilitate the manipulation of the front plate member during its insertion into the mould.

Of course, if necessary or required, it is possible to fix the locating body onto the protrusions. Furthermore, if it is not possible or required to engage the locating body on keying means, it may be adhered or otherwise fixed to the front plate member.

In a preferred embodiment, the locating body is formed from a meltable plastics material. For example, the locating body is formed from the same material as said body member. Preferably, the locating body and the body member are both formed from a polycarbonate plastics material.

In this manner, the molten material of the body member introduced into the mould can be arranged to coalesce with at least a portion of the locating body.

In a preferred embodiment, the locating member comprises a tab member extending outwardly of said locating body.

Preferably, a substantial part of the profile of the locating body is arranged to conform with at least a portion of the periphery of the front plate member. The locating body may be provided with a tab member for extending beyond the periphery of said front plate member and to form said locating member.

In an embodiment, said front plate member is substantially circular, and said locating body is substantially C-shaped.

The present invention also extends to an indicator or push-button member formed by a method as defined above.

According to a further aspect of the present invention there is provided an indicator or push-button member comprising a front plate member mounted on a body member, and a locating body interposed between said front plate member and said body member, wherein said body member has been formed by moulding and the locating body is retained in its interposed position as a result of the moulding of the body member, and wherein said locating body carries a locating member extending outwardly of the periphery of said front plate member.

The locating member may be retained on the indicator or push-button member to perform other locating functions.

Alternatively, the locating member may be removed from the indicator or push-button member as and when required. For example, it would generally be the case that the peripheral surface of the junction between the front plate member and the body member will be worked so as to remove the sprue therefrom. This can be by trimming or by any other means.

The locating member may advantageously be removed during the trimming operation, so that no further process steps are required at the time of finishing the indicator or push-button member.

In an embodiment, the material of the locating body has, at least in part, coalesced with the material of the body member.

Preferably, said front plate member is substantially circular.

Preferably, indicia are carried on the front plate member of the indicator or push-button member. In an embodiment, the indicia are formed by at least one aperture in said front plate member so that the indicia may be illuminated. In this instance, the mould, within which the front plate member is to be located, is preferably provided with recesses for receiving the apertures of the front plate member.

According to another aspect of the present invention there is provided an indicator or push-button member comprising a front plate member having indicia means thereon, a locating member extending outwardly therefrom, and arranged to be located in a mould by means of said locating member and to have a body member formed thereon in said mould.

The invention may advantageously provide for a pushbutton for use in an arrangement similar to the arrangement disclosed in GB 2 278 238 A.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a push-button assembly having a push-button member formed in accordance with an embodiment of the present invention; Figure 2 is an underneath plan view of a front plate of the push-button member of Figure 1; Figure 3 is a cross-sectional view of the front plate taken along the line II-II of Figure 2; Figure 4 is a plan view of one embodiment of a locating body according to the present invention; Figure 5 is an underneath plan view of the front plate of Figure 2 but with the locating body of Figure 4 mounted thereon; and Figure 6 is a side elevational view of a push-button member incorporating the front plate and locating body as illustrated in Figures 1 to 5.

The drawings illustrate a push-button member and the description thereof is specifically directed to a pushbutton member having indicia provided by apertures therein.

However, this is for clarity of description and it should be appreciated that the invention is equally applicable to indicator members. Furthermore, whilst the invention is particularly useful where the indicator or push-button member has a front plate which is generally circular, the invention is not limited to the utilisation of circular front plates only. Similarly, although the invention finds particular relevance where the front plate carries indicia it may also be used where no such indicia are provided.

Furthermore, the indicia, if such are provided, need not be alphanumeric. For example, if there is a grain or striation in the front plate it is often preferred to have that grain or striation running in a particular way and the present invention can be used to ensure that this is the case.

Figure 1 shows a plan view of a push-button assembly 10 formed in accordance with an embodiment of the present invention. The push-button assembly 10 comprises a substantially rectilinear housing 12 in which is mounted a generally circular push-button member 14 having a circular front, or pressel, plate 16 providing the outer surface of the push-button member 14.

The pressel plate 16 has two machined or cut apertures 18, 20 formed therein. During the formation of the pushbutton member 14, a body member 40 (Figure 6) is moulded and secured onto the rear or underside of the pressel plate 16 as will be described further below. The present invention enables the pressel plate 16 to be accurately orientated in a mould, and thus enables the pressel plate 16 to be accurately orientated with respect to the body member to be formed thereon. Generally, the moulded body member carries mounting means to engage the push-button member relative to a housing. It will be appreciated that if the pressel plate is accurately aligned with respect to the body member, it will similarly be accurately aligned with respect to the housing when the body member is engaged therewith.

The mould cavity in which the pressel plate 16 is located during formation of the body member thereon has recesses in its base to accommodate the indica carried on the pressel plate. Thus, the mould cavity receiving the pressel plate 16 illustrated will have two recesses which correspond in size and shape to the numerals 2 and 8 as shown in Figure 1. As will be described later, the pressel plate 16 of the push-button is positioned on the base surface of the mould cavity so that the apertures 18, 20 register with the correspondingly shaped recesses formed in the the base. Thus, as will be appreciated, during introduction of molten material into the mould cavity, which molten material is arranged to solidify to form the body member of the push-button 14, some of this material extends through the apertures 18, 20 and into the recesses formed in the base of the mould cavity.Thus, in the finished push-button member, the numerals are formed of raised portions of the body member material which extend beyond the surface of the pressel plate 16 of the pushbutton 14.

The material forming the body member, and thus the raised portions of the numerals 2 and 8 as they appear on the push-button of Figure 1, is advantageously formed of a translucent or transparent material so that the push-button 14 is arranged to be illuminable.

As will be appreciated, the formation of a suitable push-button 14 without fault or defect, particularly as regards the formation of the raised numerals, depends very much upon the accurate location of the pressel plate 16 in the mould cavity. For example, in order to form an accurate representation of the numerals 2 and 8, exact registration between the recesses formed in the base of the mould cavity and the recesses 18, 20 in the push-button front plate 16 is required. Also, the surface of the pressel plate 16 is often required to have a brushed appearance and, in order to enhance this appearance, it is often required that the direction of the pattern corresponds to the orientation of the numeral appearing in the push-button 14. Again, accurate location of the pressel plate 16 of the push-button 14 is required so as to achieve the appropriate orientation. Of course, when mounted in the housing 12 for use, the push-button 14 should generally be orientated such that the numerals appear in an upright disposition.

One particular embodiment of the present invention which assists in achieving the aforementioned requirements is now described particularly with reference to Figs. 2, 3, 4 and 5.

Figure 2 shows a plan view of the underside of the pressel plate 16. As will be seen, in addition to the apertures 18, 20, the pressel plate 16 is also provided with a pair of diametrically spaced, projecting weldstuds 26, 28 each arranged near the outer periphery of the circular front plate 16.

The cross sectional view provided in Figure 3 illustrates the form of the weldstuds 26, 28 which can be used to facilitate the manipulation of the front plate 16 from a storage location into the lower region of the mould cavity (not shown). The weldstuds 26, 28 are provided, in well known manner, to key the body member to be formed to the front plate 16.

In order to provide for the accurate location of the pressel plate 16 on the base surface of the mould cavity, a locating member is provided which is arranged to extend from the outer periphery of the circular pressel plate 16.

In the illustrated embodiment, the locating member is provided on a substantially C-shaped locating body 30 as shown in Figure 4.

As can be seen in Figure 4, the locating body 30 is in the form of a substantially C-shaped plate 32 formed of plastics material, preferably polycarbonate, and has a pair of notches 34, 36 provided in the radially outer surface thereof. A locating member, in the form of a tab portion 38, is also provided on the locating body 30 and is arranged to extend outwardly from the C-shaped body 32 along a line centred on the axis of curvature of the Cshaped body 32.

The locating body 30 is arranged to be mounted on the underside of the pressel plate 16, i.e. the side visible in Figure 2, by engagement of the notches 34, 36 with the weldstuds 26, 28 respectively. As will be appreciated, the locating body 30 is preferably resiliently deformable so that the C-shaped body 30 may be deformed to facilitate the engagement of the weldstuds 26, 28 in the respective notches 34, 36.

Once the C-shaped locating body 30 is engaged on the pressel plate 16, the pressel plate 16 has the appearance illustrated in Figure 5 in which the locating tab 38 extends substantially radially thereof. It will be appreciated that, if, at any stage, the locating body 30 suffers any form of damage or dislodgement, it may be replaced by a new locating body.

The pressel plate 16 with the locating body 30 engaged thereon, as shown in Figure 5, may then be located on the base of a mould cavity for the formation of the body member on the pressel plate 16.

The pressel plate 16 is located within the mould cavity by way of the locating tab 38. In this respect, a suitable formation, such as a recess, will be provided within the mould cavity to receive the locating tab 38. It will be appreciated that, in this manner, the pressel plate will be accurately located within the mould cavity so that, for example, recesses in the base of the mould cavity will be in registry with the apertures 18, 20 of the pressel plate 16 as described above. Thus, by virtue of the engagement of the locating body 30 on the pressel plate 16, the accurate location of the front plate in the mould cavity, and indeed with regard to any other features requiring accurate relative location/orientation of the front plate and as discussed above, can be achieved in a readily adaptable and simple manner.Further, the accurate location of the pressel plate 16 in the mould cavity does not require any marking or any other possibly damaging adaption of the front surface of the pressel plate 16.

Once the moulding process is complete, the push-button 14, comprising the pressel plate 16 and the moulded body member 40, is removed as a unitary member from the mould cavity. Subsequently, the push-button 14 may be engaged by way of mounting means formed on the body in a housing, for example, in the rectilinear housing 12 of Figure 1.

Prior to the receipt of the push-button in a housing, however, the locating tab 38 which remains between the pressel plate 16 and the body member 40, and extends outwardly thereof, may be clipped or otherwise removed. In particular, subsequent to the moulding process, the outer surface of the body member 40 is arranged to be trimmed, or otherwise smoothed, so as to enhance the appearance thereof. Such processing may advantageously be arranged to remove the tab member 38 extending therefrom. Thus, the use of the present invention does not necessarily entail any further processing steps subsequent to the removal of the push-button member 14 from the mould cavity.

Advantageously, the body member 40 of the push-button 14 is arranged to be formed of the same polycarbonate plastics material as that of the locating body 30. This can serve to disguise the location of the locating body 30 within the body of the push-button 14.

The invention is not restricted to the details of the foregoing embodiment. For example, any required indicia may be provided in the front plate, or the front plate may be left plain. Any form of locating member may be provided so long as it extends outwardly for example, as the tab portion 38, and is arranged to engage with the mould cavity and to enable accurate location of the front plate within the mould cavity. As explained above, the locating member has no effect on the quality of the front surface of the front plate since no marking, or other form of adaption, of that surface is required to achieve the accurate location of the front plate member in the mould cavity.

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 as defined by the appended claims.

Claims

1. A method of forming an indicator or push-button member comprising a front plate member mounted on a body member, the method comprising the steps of providing on said front plate member a locating member extending outwardly of said front plate member, locating the front plate member in a mould in a required orientation by engaging said locating member with a co-operating part of said mould, and introducing molten material into the mould to form the body member on the front plate.

2. A method as claimed in Claim 1, wherein said locating member is provided on a locating body carried by said front plate.

3. A method as claimed in Claim 2, further comprising the step of engaging the locating body on said front plate member.

4. A method as claimed in Claim 3, wherein said locating body is releasably engaged on said front plate member.

5. A method as claimed in Claim 4, wherein said locating body is engaged with protrusions carried by said front plate member.

6. A method as claimed in Claim 5, wherein said protrusions extend from the underside of said front plate member and act to key the front plate member to the material of the body member.

7. A method as claimed in any of Claims 2 to 6, wherein the locating body is formed from a meltable plastics material.

8. A method as claimed in Claim 7, wherein the locating body is formed from the same material as said body member.

9. A method as claimed in Claim 7 or Claim 8, wherein said locating body is formed from a polycarbonate plastics material.

10. A method as claimed in any of Claims 2 to 9, wherein said locating member comprises a tab member extending outwardly of said locating body.

11. A method as claimed in any of Claims 2 to 10, wherein said locating body is resiliently deformable.

12. A method as claimed in any of Claims 2 to 11, wherein a substantial part of the profile of the locating body is arranged to conform with at least a portion of the periphery of the front plate member.

13. A method as claimed in any of Claims 2 to 12, wherein said front plate member is substantially circular, and said locating body is substantially C-shaped.

14. An indicator or push-button member formed by a method as claimed in any preceding claim.

15. An indicator or push-button member comprising a front plate member mounted on a body member, and a locating body interposed between said front plate member and said body member, wherein said body member has been formed by moulding and the locating body is retained in its interposed position as a result of the moulding of the body member, and wherein said locating body carries a locating member extending outwardly of the periphery of said front plate member.

16. An indicator or push-button member as claimed in Claim 15, wherein the material of the locating body has, at least in part, coalesced with the material of the body member.

17. An indicator or push-button member as claimed in Claim 15 or Claim 16, wherein said front plate member is substantially circular.

18. A method of forming an indicator or push-button member substantially as hereinbefore described with reference to the accompanying drawings.

19. An indicator or push-button member substantially as hereinbefore described with reference to the accompanying drawings.