This invention relates to push button assemblies and is particularly although not exclusively concerned with panel-mounted push button assemblies for use in amusement or gaming machines. Conventionally, a push button assembly for an amusement or gaming machine has a housing mountable on a panel of the machine and comprises a light-transmitting button which is manually movable within the housing against a spring to operate an electrical switch which may be a microswitch mounted at an inner end of the housing. The light- transmitting button can be illuminated, e.g. by an internal lamp, to indicate the functional status of the switch i.e. to indicate whether the switch is currently operable to initiate a game play function. The switch may be operable to initiate different functions at different stages of the game. However, the switch is usually operable to initiate one function at a particular stage in the game.

An object of the invention is to provide a push button assembly which has greater versatility.

According to the invention therefore there is provided a push button assembly comprising a housing mountable on a panel, a fixing means for fixing the housing relative to the panel, a manually operable switch mechanism mountable relative to the housing, characterised in that the switch mechanism is provided by a membrane having discrete, independently manually operable switch areas thereon.

With this arrangement the button assembly has enhanced versatility insofar as it can be used to initiate a variety of different functions depending on which switch on the membrane is operated. Thus a possible use of the button assembly would be for navigation around a

screen or menu.

Preferably, the membrane is exposed so that the switch mechanism is manually operable by direct manual contact with the membrane e.g. by pushing generally in the manner of a conventional button. Preferably, the housing comprises a flange which receives the membrane at one end of a tubular stem. The flange may be of a generally circular or square or rectangular or polygon configuration. The flange may be bounded by a peripheral wall or bezel to define a receptacle therewith. A retention device such as a retainer ring may fit within the bezel to hold the membrane in position.

The housing may be externally threaded for interengagement with the fixing means which may comprise a nut or additionally spring clips or other suitable means may be provided for fixing the housing relative to the panel. Illumination means may be provided for illuminating the housing and/or the membrane, particularly the aforesaid bezel.

The illumination means may comprise LEDs on a circuit board mounted beneath the aforesaid flange.

The button assembly preferably comprises a support member for supporting the membrane and which may be interposed between the membrane and the aforesaid flange. The support member may comprise a disc-shaped member which may be light-transmitting. The disc-shaped member may be attached to a hollow stem which may fit within the aforesaid tubular stem of the housing. Preferably, the membrane comprises a base layer and a top layer.

The base layer may incorporate an electrical circuit which may be a printed circuit and the top layer may provide switch elements contactable

with the electrical circuit. The switch elements may be in the form of a plurality of depressible domed structures, which are normally spaced from the electrical circuit.

Preferably, the membrane has a connector for connection to appropriate circuitry of an amusement or gaming machine.

The membrane may be light transmitting.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a plan view of one form of a push button assembly according to the invention;

Figure 2 is an exploded sectional view of the button assembly in Figure 1 ; and

Figure 3 is an exploded sectioned view of the button assembly in Figure 1 . As shown in figures 2 and 3, a button assembly has a housing 1 , a button support 2, a button membrane 3, and a retainer 4.

The housing 1 comprises a tubular stem 6 of generally circular cross-section formed integrally at a top end with a button receiving part defined by a radially outwardly extending annular peripheral flange 5, bounded by an upwardly extending cylindrical inner wall 5a and an outer peripheral wall 5b which is inclined outwardly downwardly from its top circular rim which is connected to the top circular rim of the inner wall 5a, to a bottom circular rim 7 which is free and terminates slightly below the flange 5. The tubular stem 6 has a screw thread on its exterior. The stem

6, at a position in the bottom end region, has two part-circumferential internal flanges 1 7 of L-shaped cross-section with gaps 1 8 therebetween

at diametrically opposed positions.

The upstanding walls 5a, 5b define a bezel around the top end of the tubular stem 6. The outer wall 5b is provided with apertures 21 equally spaced around the periphery. There are further apertures 24 located in the flange 5. An annular circuit board (not shown) is provided which is located under the flange 5, between the tubular stem 6 and the bottom rim 7 of the outer wall 5b such that the underside is level with such rim. The board 22 includes LEDs spaced circumferentially and also radially in positional correspondence with the apertures 21 , 24. The LEDs are connected via circuitry to a plug (not shown) for connection to appropriate control circuitry.

The support button 2 comprises a generally circular light transmitting disc-shaped member 10 and an integral smaller diameter coaxially arranged tubular stem 8 extending downwardly from the underside of the member 10. The member 10 has a protruding peripheral ring 1 1 disposed generally centrally on the outer surface of the member 10 and a peripheral protruding lip 1 2 at its bottom end.

The tubular stem 8 has a generally central circumferential abutment 1 9 on its inner surface and a pair of legs 9 with outwardly turned feet 20 projecting downwardly at diametrically opposed positions.

The button membrane 3 is disc-shaped and of the same size on the top circular face of the disc-shaped member 10. The membrane 3 is composed of a base layer 13 incorporating an electrical circuit (not shown) and a top layer 14 providing four switch operating mechanisms or buttons in the form of raised domes 1 5. The raised domes 1 5 are each disposed over a part of the electrical circuit which is incomplete, the respective domes, each acting to bridge the gap in the circuit when

depressed, thereby to provide four discrete switches. The top layer 14 is printed on each of the raised domes 1 5 to indicate its function as an actuating button of the respective switch. A connector is integrated into the membrane 3 for connection of the switches to circuitry to be controlled thereby.

The membrane 3 is mounted on top of the member 10.

The annular circuit board beneath the flange 5 has LEDs in alignment with apertures 24 in the flange base wall 25, which are in turn aligned with the peripheral domes 1 5. The retainer 4 is an annular member provided with a protruding flange 16 around the upper inner periphery.

When assembled, the retainer 4 snap fits tightly round the member 10 over the membrane 3 in engagement with the ring 1 1 of member 10, to rest on lip 12, the lip 16 holding the membrane 3 in place on the member 10. The legs 9 are springy and these are inserted into the tubular stem 6 through gaps 18, until the feet 20, spring outwardly into position beneath the bottom end of the stem 6 to secure the support 2 within the housing 1 . In this position the member 10 is held on top of the flange 5.

In use, the button assembly may be fixed to the screen or panel of an amusement or gaming machine. The stem 6 is passed through an aperture in a panel which is of slightly larger diameter than the stem 6 so that the flange 5 lies over the panel with the annular circuit board between the panel and the underside of the flange 5 and the rim 7 engaging the panel. The button assembly is secured in position on the panel with a nut (not shown) which is screwed onto the external thread of the stem 6 at the underside of the panel.

The annular circuit board with LEDs beneath the flange and the

connector of the membrane 3 are connected through the machine panel to the operating circuitry of the amusement or gaming machine.

At appropriate stages in the game played with the machine the domes on the membrane can be depressed to operate the respective electrical switch to control a machine function. In this case, one of the domes can be pressed by a player as a press button whereby the dome is depressed, the electrical circuit relating to that dome is completed by contact of the interior of the dome against the circuit which supplies an electrical signal to the machine operating circuitry. The domes can be lit by their respective LEDs to indicate which switch has been pressed or which is available for controlling a machine function.

Also, on appropriate occasions power can be supplied to the LEDs on the circuit board aligned with apertures 21 to cause these to be illuminated. Illumination of these LEDs causes the light being emitted to travel up optical fibres provided in the apertures 21 to produce a ring of illuminated dots in a path around the flange. The LEDs may be white, coloured or colour controllable and therefore the illumination of the individual dots may be of different colours, in a constant or flashing manner whereby there is a wide range of illumination combinations which can be used to give a wide range of game play indications.

If desired, a lamp unit (not shown) may be mounted within the stem 6 at the bottom end thereof for illumination from below the membrane 3, via the member 10 which are both light-transmitting. Also the button support 2 may be movably mounted within the stem 6, a spring being provided between the abutments 17 and 19 to allow limited movement of the frame in an upward and downward

direction to give a springy feel to the operation of the membrane switches.

With the embodiment described above the button assembly can be used for controlling different functions due to the multiple switches of the membrane 3. This gives enhanced versatility.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment, which is described by way of example only.