GB2150353A

GB2150353A - Push button switch

Info

Publication number: GB2150353A
Application number: GB08414686A
Authority: GB
Inventors: David Partridge
Original assignee: Starpoint Electrics Ltd
Current assignee: Starpoint Electrics Ltd
Priority date: 1983-11-23
Filing date: 1984-06-08
Publication date: 1985-06-26
Also published as: GB8331269D0; GB2150353B; GB8414686D0

Abstract

The main body portion 26 of a push button switch, including a bezel 11 is moulded by a normal injection moulding process. Two of these mouldings are then inserted in a further moulding tool comprising a moving half 21 and a fixed half 22. With the two halves of the tool fully closed, molten plastics material is injected at 31 and flows into the two ring-shaped spaces surrounding the bezel portions 11 of the two mouldings 26. The resultant moulded rings 14 are thus firmly bonded to the inner part of the bezel 11 of each moulding. The portions 11 and 14 are moulded in contrasting colours so that, when seen from the front, the visible face of the bezel comprises an outer portion in one colour and an inner portion in a different colour, preferably white or a lighter colour than that of the outer portion. <IMAGE>

Description

SPECIFICATION Push button switch This invention relates to push button switches, particularly those of the kind used in gaming or amusement machines where there is frequently a battery of such switches for controlling the different functions of the machine. The buttons of the switches may be circular, square or rectangular and frequently have a transverse dimension of several centimetres. When used in such a context, the appearance of the switches is just as important as their electrical functioning and when a number of different switches are mounted together in close association, the buttons may be made in a variety of bright colours. In each individual switch, the button itself is surrounded by a bezel which is frequently black or some other dark colour which, by contrast with the bright colour of the button, enhances the overall appearance of the switch.

According to the present invention, the appearance is still further enhanced by forming the bezel for a push button switch of this type as a two-shot plastics moulding in contrasting colours so that the visible face comprises an outer portion in one colour and an inner portion or frame surrounding the button itself in a different colour, preferably white or a lighter colour than that of the outer portion. By framing the button in a lightercolourwhich contrasts with the darker colour of the remainder of the bezel, the outline of the button is accentuated and the overall appearance is rendered more attractive.

Preferably the inner portion or frame of the bezel is moulded as part of the main body of the switch, as the first shot of the moulding, and the outer portion is moulded around it as the second shot. The alternative is also possible, however. In other words, the outer portion of the bezel may be moulded as part of the main body of the switch and the inner portion or frame is then added subsequently as the second shot of the moulding.

An example of mould and its method of operation, as used for the second shot of a moulding operation in accordance with the invention, will now be described with reference to the accompanying draw ings, in which: Figure 1 is a longitudinal sectional view of the main body portion of a push button switch (without the button itself in position) moulded as the first shot in a two-shot moulding process; Figure 2 is a similar view, but showing an additional portion moulded in position as the result of the second shot of the process; Figure 3 is a sectional view of a moulding tool used in the second shot of the moulding process for the production of the moulding shown in Figure 2, the view showing the tool in the closed position and only the inserts of the tool, the bolster being omitted for clarity; and Figure 4 is a view corresponding to Figure 3, but with the tool in the open position and also showing a completed two-shot moulding in the process of being ejected.

The main body portion of the switch shown in Figure 1 is moulded by a normal injection moulding process which requires no description. The button of the switch which, of course, forms a separate component, fits into the space shown as 10 and is surrounded by a bezel 11 which is constituted by the front edge of the moulding. The rear portion of the moulding 12 is tubular for the reception of a shank portion of the button. Apart from the width of the bezel 11, which is narrower than normal, the moulding shown in figure 1 is a well-known standard product.

The inventive feature lies in the addition of a moulded ring 14 seen in Figure 2 and the front edge of which 15 forms an extension of the bezel 11 which is thus made up of an inner portion 11 and an outer portion 15. The ring 14 is moulded in a contrasting colour to the remainder of the moulding, normally darker than the remainder so that when the button is fitted in position, it is framed by a lighter coloured portion 11 of the bezel surrounded by a darker portion 15.

The moulding of the ring 14 is achieved in a form of moulding tool illustrated in Figures 3 and 4. This comprises a moving half 21 and a fixed half 22 which meet along a split line 23. In Figure 3, the moving half 21 is illustrated in the closed position in contact with the fixed half 22, but it is capable of being moved to the left as indicated by the arrow into an open position in which access is given to the moulding spaces, as shown in Figure 4. The tool is designed for the simultaneous production of two mouldings as illustrated in Figure 2, the moulding spaces being defined by hardened inserts 24. In use, the moving half 21 is moved to the left to the open position of Figure 4 and two mouldings as illustrated in Figure 1 are inserted in the fixed half 22.The moving half 21 is then moved to the right to the closed position as illustrated, leaving moulding spaces corresponding to the ring 14 illustrated in Figure 2. These communicate via a gate 30 with an injection point 31.

With the two halves of the tool fully closed together, molten plastics material, e.g. acrilonitrilebutadiene-styrene is injected at 31 and flows through the gate 30 into the two ring-shaped spaces surrounding the portions 11 of the two mouldings 26. The resultant moulded rings 14 are thus firmly bonded to the inner part of the bezel 11 of each moulding. After a predetermined time during which the plastic hardens, the tool is opened, the moving half 21 moving to the left as indicated by the arrows in Figure 4 and carrying the complete moulding, i.e.

including the two first-shot mouldings, a runner 32 and portions connecting the runner to the moulded rings 14, indicated collectively as 26. The runner 32 has an undercut portion 34 which ensures that the resultant moulding is retained by the moving half 21 and withdrawn from the fixed half 22. The moving half 21 also includes ejector pins 35 extending from a backing plate 36 and movement of this plate to the right in relation to the moving half 21 causes the pins 35 to project into engagement with the mouldings 26 and thus push these mouldings out of the moving half 21 with the runner 32 intact, as shown in Figure 4.

Since the purpose of the improvement of the invention is to enhance the appearance of the bezel of the switch, it is important that the front surface of the bezel, including the inner portion 11 and the outer portion 15 should be flat and smooth and that the line of demarcation between the two portions should be clean and continuous. It is thus important that the front edge 11 of the first-shot moulding shown in Figure 1 should be flat and level so that it forms a close seal with the face of the mould cavity which must also of course be completely flat. This ensures that when the material of the second colour is injected as illustrated in Figure 3, there is no tendency for it to spill through onto the front face 11 and thus blur the line between the two portions of different colours.

Accurate location of the two mouldings 26 in the fixed half 22 is also important because any move ment of these mouldings when the two halves close together, resulting from any inaccuracy, would prevent accurate location of the surfaces 11 with the moulding surfaces and would lead to the risk of trapping of parts of the mouldings 26 at the split line 23. The overall moulding parameters must, of course, be carefully determined so as to avoid any possible damage to the first-shot moulding, particularly around the bezel portions so as to obtain a firm fusion between the moulded ring 14 and the portion 11 which it surrounds.

Claims

1. A push button switch having a bezel formed as a two-shot plastics moulding in contrasting colours so that the visible face comprises an outer portion in one colour and an inner portion or frame surrounding the button itself in a different colour.

2. A push button switch according to claim 1 in which the inner portion of the bezel forms part of the main body of the switch, as the first shot of the moulding, and the outer portion is moulded around it as the second shot.

3. A push button switch according to claim 1 produced by a method substantially as described and as illustrated with reference to the accompanying drawings.

4. A method of producing a body for a push button switch including a bezel surrounding the button of the switch, by means of a two-shot moulding process, in which, after the main part of the body has been moulded, an outer part of the bezel is moulded in a contrasting colour as a result of the second shot of moulding.