GB2023937A

GB2023937A - Electric push-button switches

Info

Publication number: GB2023937A
Application number: GB7921474A
Authority: GB
Original assignee: ITW Ltd
Current assignee: ITW Ltd
Priority date: 1978-06-21
Filing date: 1979-06-20
Publication date: 1980-01-03

Abstract

A domed resilient diaphragm 12 is arranged to flex, and a plunger 14 is arranged to move, with respect to the switch housing, in response to depression of a push-button for effecting operation of a switch mechanism such as microswitch 36, the diaphragm permitting such movement of the plunger while serving to return itself, the plunger and push-button to normal position when the push-button is subsequently released. The top surface of the diaphragm 12 preferably constitutes the push-button, and the diaphragm 12 and plunger 14 are preferably an integral plastics moulding, which, in conjunction with a rubber ring 16 and circlip 24, forms a dust and moisture seal. The plunger may act on two microswitches side-by-side. <IMAGE>

Description

SPECIFICATION Electric push-button switches An electric push-button switch, in accordance with the present invention, comprises a domed resilient diaphragm which is arranged to flex with respect to a switch housing, and a plunger which is arranged to move with respect to the switch housing, in response to depression of a push-button for effecting operation of switch mechanism, the diaphragm permitting such movement of the plunger while serving to return the plunger to its normal position when the push-button is subsequently released.

Preferably, the diaphragm is integrally formed with the plunger, conveniently presenting a onepiece plastics moulding of mushroom-like overall shape, with a surface of the diaphragm itself constituting the push-button and thus forming an exposed part of the electric switch. Alternatively, the diaphragm may be constituted by a plastics moulding and have an opening therein through which the plunger extends. In the latter construction, the plunger may be formed with a head constituting the push-button which bears down on the diaphragm during operation of the electric switch.

It may be arranged that the periphery of the diaphragm is pressure sealed within a recess of the switch housing in order to reduce substantially any ingress of dust and moisture into the switch housing.

Three electric push-button switches, according to the present invention, will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a vertical section showing a first of the switches in both its normal and operational positions; Figure 2 is similar to Figure 1 but shows both the normal and operational positions of the second of the switches; Figure 3 is a section of a third switch; and Figure 4 is a side elevation, viewed in the direction of the arrow IV in Figure 3, and showing a carrier before assembly with a switch body.

In Figure 1 an electric push-button switch 10 is shown including a domed diaphragm 12 of moulded plastics construction having an integral plunger 14.

The periphery of the diaphragm 12 seats against a rubber sealing ring 16 carried in a generally cylindrical recess 18 in switch housing 20. The plunger 14 passes through an opening 22 in the switch housing 20 and is held captive by means of a circlip 24 which is a snap fit in a circumferential groove in the plunger 14. The central outer part of the switch housing 20 has a thread 26 to permit clamping by a nut (not shown) to an apertured support plate 28. A further rubber sealing ring may be provided at 30 and the switch housing may have a flat as indicated at 32 to prevent rotation.

The assembly is such that the diaphragm 12 makes pressure engagement with the ring 16 in the normal position of the switch 10, as illustrated in the left-hand portion of Figure 1,the diaphragm 12 being pressed slightly to enable the circlip 24 to be inserted in the groove of the plunger 14, such pressure engagement resisting entry of dust and moisture to the switch housing 20.

In use, the exposed part of the diaphragm 12 is depressed by hand so that it assumes the operational position shown in the right-hand portion of Figure 1. This causes the diaphragm 12 to flex and the bottom end (as shown) of the plunger 14 to move against operating button 34 of a conventional microswitch 36. The micro-switch 36 may be releasably secured to the switch housing 20 by pins 38 passing through aligned bores 40 formed in both the switch housing and the micro-switch itself. Upon release of the diaphragm 12, the diaphragm returns to its normal position and thus releases the plunger 14 from the operating button 34 of the micro-switch 36.

In an alternative electric push-button switch 10a, shown in Figure 2, like components utilise like reference numerals with the suffix "a". In this embodiment, however, the diaphragm 12a is formed quite separately from the plunger 14a. A generally cylindrical push-button 42 is formed at the head of the plunger 14a which passes through an opening in the diaphragm 12a. Apart from consequential differences to the shape of the switch housing 20a, and the fact that a pair of conventional micro-switches 36a in side-by-side relationship are operated simultaneously by the single plunger 14a, the assembly and use of the switch 10a is substantially the same as that for the switch 10.The assembly is such that, as illustrated in the left-hand portion of Figure 2, the diaphragm makes pressure engagement with its outer periphery against the switch housing 12a, and with its inner periphery against the push-button 42, thus resisting entry of dust and moisture.

Figures 3 and 4 show a switch which is a modification of the switch shown in Figure 1. There is a diaphragm 12b integral with a plunger 14b. In place of a circlip 24, the plunger carries an actuator 44 of sufficient diameter to cooperate with the buttons 34b of two micro-switches 36b. The actuator is a force fit on a reduced lower end of the plunger 14b.

The switch housing is in two parts, namely a body 46 and a carrier 48. The micro-switches 36b are secured to the carrier 48 by pins 38b. The carrier 48 is releasably secured to the body 46 by two resilient legs 50 on the carrier cooperating with a ledge within the body. With this arrangement, a user can select a body 46 with a particular colour of push button (the visible surface of the diaphragm 126), and a carrier 48 with switches 36b having a particular contact arrangement, and assemble them together to satisfy a particular requirement.

As will be appreciated from the foregoing description, electric push-button switches in accordance with the present invention are of extremely simple construction, requiring only relatively few parts which can themselves be readily produced as by plastics moulding, thereby keeping production costs to a minimum.

1. An electric push-button switch comprising a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electric push-button switches An electric push-button switch, in accordance with the present invention, comprises a domed resilient diaphragm which is arranged to flex with respect to a switch housing, and a plunger which is arranged to move with respect to the switch housing, in response to depression of a push-button for effecting operation of switch mechanism, the diaphragm permitting such movement of the plunger while serving to return the plunger to its normal position when the push-button is subsequently released. Preferably, the diaphragm is integrally formed with the plunger, conveniently presenting a onepiece plastics moulding of mushroom-like overall shape, with a surface of the diaphragm itself constituting the push-button and thus forming an exposed part of the electric switch. Alternatively, the diaphragm may be constituted by a plastics moulding and have an opening therein through which the plunger extends. In the latter construction, the plunger may be formed with a head constituting the push-button which bears down on the diaphragm during operation of the electric switch. It may be arranged that the periphery of the diaphragm is pressure sealed within a recess of the switch housing in order to reduce substantially any ingress of dust and moisture into the switch housing. Three electric push-button switches, according to the present invention, will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a vertical section showing a first of the switches in both its normal and operational positions; Figure 2 is similar to Figure 1 but shows both the normal and operational positions of the second of the switches; Figure 3 is a section of a third switch; and Figure 4 is a side elevation, viewed in the direction of the arrow IV in Figure 3, and showing a carrier before assembly with a switch body. In Figure 1 an electric push-button switch 10 is shown including a domed diaphragm 12 of moulded plastics construction having an integral plunger 14. The periphery of the diaphragm 12 seats against a rubber sealing ring 16 carried in a generally cylindrical recess 18 in switch housing 20. The plunger 14 passes through an opening 22 in the switch housing 20 and is held captive by means of a circlip 24 which is a snap fit in a circumferential groove in the plunger 14. The central outer part of the switch housing 20 has a thread 26 to permit clamping by a nut (not shown) to an apertured support plate 28. A further rubber sealing ring may be provided at 30 and the switch housing may have a flat as indicated at 32 to prevent rotation. The assembly is such that the diaphragm 12 makes pressure engagement with the ring 16 in the normal position of the switch 10, as illustrated in the left-hand portion of Figure 1,the diaphragm 12 being pressed slightly to enable the circlip 24 to be inserted in the groove of the plunger 14, such pressure engagement resisting entry of dust and moisture to the switch housing 20. In use, the exposed part of the diaphragm 12 is depressed by hand so that it assumes the operational position shown in the right-hand portion of Figure 1. This causes the diaphragm 12 to flex and the bottom end (as shown) of the plunger 14 to move against operating button 34 of a conventional microswitch 36. The micro-switch 36 may be releasably secured to the switch housing 20 by pins 38 passing through aligned bores 40 formed in both the switch housing and the micro-switch itself. Upon release of the diaphragm 12, the diaphragm returns to its normal position and thus releases the plunger 14 from the operating button 34 of the micro-switch 36. In an alternative electric push-button switch 10a, shown in Figure 2, like components utilise like reference numerals with the suffix "a". In this embodiment, however, the diaphragm 12a is formed quite separately from the plunger 14a. A generally cylindrical push-button 42 is formed at the head of the plunger 14a which passes through an opening in the diaphragm 12a. Apart from consequential differences to the shape of the switch housing 20a, and the fact that a pair of conventional micro-switches 36a in side-by-side relationship are operated simultaneously by the single plunger 14a, the assembly and use of the switch 10a is substantially the same as that for the switch 10.The assembly is such that, as illustrated in the left-hand portion of Figure 2, the diaphragm makes pressure engagement with its outer periphery against the switch housing 12a, and with its inner periphery against the push-button 42, thus resisting entry of dust and moisture. Figures 3 and 4 show a switch which is a modification of the switch shown in Figure 1. There is a diaphragm 12b integral with a plunger 14b. In place of a circlip 24, the plunger carries an actuator 44 of sufficient diameter to cooperate with the buttons 34b of two micro-switches 36b. The actuator is a force fit on a reduced lower end of the plunger 14b. The switch housing is in two parts, namely a body 46 and a carrier 48. The micro-switches 36b are secured to the carrier 48 by pins 38b. The carrier 48 is releasably secured to the body 46 by two resilient legs 50 on the carrier cooperating with a ledge within the body. With this arrangement, a user can select a body 46 with a particular colour of push button (the visible surface of the diaphragm 126), and a carrier 48 with switches 36b having a particular contact arrangement, and assemble them together to satisfy a particular requirement. As will be appreciated from the foregoing description, electric push-button switches in accordance with the present invention are of extremely simple construction, requiring only relatively few parts which can themselves be readily produced as by plastics moulding, thereby keeping production costs to a minimum. CLAIMS

1. An electric push-button switch comprising a switch housing, a domed resilient diaphragm mounted peripherally to the housing and able to flex with respect to the housing, switch mechanism mounted to the housing, means consituting a pushbutton movable with the centre of the diaphragm, and a plunger movable with respect to the switch housing and associated with the centre of the diaphragm, and adapted to cooperate with the switch mechanism, whereby manual depression of the push-button causes displacement of the plunger relative to the switch housing and consequent operation of the switch mechanism, and upon manual release of the push-button the diaphragm returns itself, the plunger and push-button to normal position with consequent release of the switch mechanism.

2. A switch according to claim 1, in which the diaphragm is integrally formed with the plunger.

3. A switch according to claim 2, in which the diaphragm and plunger are a one-piece plastics moulding of mushroom-like overall shape.

4. A switch according to any of claims 1 to 3, in which one surface of the diaphragm serves as the push-button.

5. A switch according to any of claims 1 to 3, in which the switch mechanism is within a microswitch unit, which is secured to the switch housing.

6. A switch according to any of claims 1 to 3, in which the switch mechanism is within a microswitch unit, which is secured to a carrier, the carrier being releasably secured to a body of the switch housing.

7. A switch according to claim 1, in which, in normal position, the diaphragm makes pressure engagement with cooperating means in a recess of the switch housing, thereby resisting entry of dust and moisture into the switch housing.