GB2084802A

GB2084802A - Keypad buttons

Info

Publication number: GB2084802A
Application number: GB8031452A
Authority: GB
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1980-09-30
Filing date: 1980-09-30
Publication date: 1982-04-15
Also published as: IE810960L; ZA812855B; IE51112B1; GB2084802B; HK49987A; SG13887G

Abstract

A push-button for use, for instance, on a telephone keypad, consists of a rectangular pad 7 of an insulating material in a cut out in a supporting frame 1,2 of the same material and coupled along one edge by an integral hinge 8 of reduced thickness, the pad being additionally supported by a pair of integral arms 11 extending between the end of the actuating portion 9 and the frame. As used in a telephone keypad the push-buttons are made in an integral one piece structure (20), which is fitted in the telephone with each push-button head (21) projecting through a hole in a cover plate (22). Below the structure 20 there is a dimple pad (23) with a dimple switch per push-button. The resilience of the button material plus the resilience of the dimple causes button restoration. <IMAGE>

Description

SPECIFICATION Keypad buttons This invention relates to the construction of electrical push-button operated switches, espe cialiy but not exclusively for use in telephone instruments.

A recent development in the field of such manually operable switching is the use of a rubber (or rubber-like material) dimple pad, which is a sheet of the rubber (or rubber-like material) with a dimple for push-button position. Each such dimple is a dome on the sheet surface which has on its concave (inner) surface a region of conductive matrices e.g.

metal or conductive plastics. The dimple pad is located over a sheet of an electrically insulating material having electrically conductive regions on it. When a push-button is depressed, its dimple's dome is collapsed so that its conductive region contacts the conductive regions on the lower sheet to complete one or more connections. On release of the pushbutton it restores to rest, assisted by the resilience of the dimple. In the case of a telephone-keypad we use a 4 X 3 dimple pad, with a corresponding matrix of conductive tracks on the lower sheet.

An object of the matrices is to produce a simple and inexpensive push button switch using such dimple switches, and to produce a keypad using such push-buttons.

According to the invention there is provided a push-button arrangement, which includes a substantially rectangular portion of an electrically insulating material formed integral with a supporting structure of the same material, the rectangular portion being coupled to the supporting structure by a region of reduced thickness extending along one edge of the rectangular portion, which region of reduced thickness forms an integral hinge for the rectangular portion, a portion along the edge parallel to the first-mentioned edge which is depressed to operate the arrangement, and a pair of arms extending along the other edges of the rectangular portion from adjacent the depressible portions to a region on the supporting structure part-way along the length of the rectangular portion, wherein the resilience of the hinge and the arms together assist in the restoration of the depressed button when it is released, wherein when in use in an electrical device switch means is located as to be operated by the depression of the depressible portion.

According to the invention there is also provided a push-button switch arrangement, which includes a substantially rectangular portion of an electrically insulating material formed integral with a supporting structure of the same material, the rectangular portion being coupled to the supporting structure by a region of reduced thickness extending along one edge of the rectangular portion, which region of reduced thickness forms an integral hinge for the rectangular portion, a bent up part of the rectangular portion along the edge parallel to the first-mentioned edge, which bent-up part is depressed to operate the switch, a pair of arms each extending along one of the other pair of edges of the rectangular portion from adjacent the bent-up part to a region on the supporting structure part-way along the length of the rectangular portion, and electrical contact means under the bentup portion of the rectangular portion and adapted to be operated when the push-button is depressed, the resilience of the hinge and the arms assist in the restoration of the depressed button when it is released.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a view from above of a pushbutton embodying the invention, which is the end-most push-button of a unitary structure of three such push-buttons.

Figure 2 is a part-sectional view along the line ll-ll of Fig. 1.

Figure 3 is a side view, looking along the arrows Ill-Ill of Fig. 1.

Figure 4 is a perspective view of a telephone keypad using twelve push-buttons each of which embodies the invention. In this case all twelve push-buttons are made as a unitary structure.

In Figs. 1 to 3, we show one end of a unitary structure which is a frame having sides 1 and 2 and two ends, one of which is shown at 3. As can be seen this end portion has two holes 4 and 5 for mounting bolts.

The push-button shown is in a cutout 6 in the frame 1-2-3, and has a rectangular portion 7 secured to and integral with the frame side 1.

The region interconnecting the side 1 and the rectangular portion 7 is, as shown at 8, Fig.

2, of reduced thickness, so that it acts as a hinge.

At the side of the portion 7 remote from its hinge 8 there is a raised portion 9 which forms the push-button as "seen" by the user.

Extending from the "push-button" edge of the portion 9 there are two arms 10, 11 each of which connects with and is integral with the frame near to the side 1, as can be seen from Fig. 2.

In use for a telephone keypad, four such units are assembled together to give a 4 X 3 matrix with each push-button head 9 projecting through a cover plate. Below these we have a 4 x 3 dimple pad of the type described above, with the conductive tracks on an insulating surface below the pad. Then when a push button is depressed it pivots about its hinge 8 and its arms 11 so as to compress the dimple underneath it. This urges the conductive material disc inside the dimple on to the conductive tracks to complete the appropriate connections.

When the push-button is released it is reset to its original condition by the resilience of the depressed dimple, plus that of the material of the push-button's hinge and arms.

In one example the push-button head has a width of 12 mm with the overall width of each button assembly of 1 7.5 mm. The width from the top of side 1 to the bottom of side 2, Fig. 1 is 20 mm. The length of the slanting porton of the arm 11 is 10 mm, while for the central push-button of the three this length is 1 2 mm, and for the other end push-button this length is 8 mm.

We now refer to Fig. 4, in which the twelve push-buttons of the keypad are moulded in a single structure. Thus we have a one-piece keypad 20. In this case it will be noted that the sidearms of the individual push-buttons are slightly bent in plan. However, this does not affect the principle on which the arrangement operates.

The button's head, such as 21 each project through a rectangular hole in a cover plate 22: in practice this hole is just wide enough for the push-button head. The dimple pad is shown at 23. If desired, in the interests of adequate sealing of the "electronics" a thin rubber or rubber-like sheet can be interposed between the frame 20 and the pad 23.

Claims

1. A push-button arrangement, which includes a substantially rectangular portion of an electrically insulating material formed integral with a supporting structure of the same material, the rectangular portion being coupled to the supporting structure by a region of reduced thickness extending along one edge of the rectangular portion, which region of reduced thickness forms an integral hinge for the rectangular portion, a portion along the edge parallel to the first-mentioned edge which is depressed to operate the arrangement, and a pair of arms extending along the other edges of the rectangular portion from adjacent the depressible portion to a region on the supporting structure part-way along the length of the rectangular portion, wherein the resilience of the hinge and the arms together assist in the restoration of the depressed button when it is released, wherein when in use in an electrical device switch means is so located as to be operated by the depression of the depressible portion.

2. A multi-push button arrangement which includes a frame which forms a supporting structure for a plurality of arrangements each as claimed in claim 1.

3. A push-button switch arrangement, which includes a substantially rectangular portion of an electrically insulating material formed integral with a supporting structure of the same material, the rectangular portion being coupled to the supporting structure by a region of reduced thickness extending along one edge of the rectangular portion, which region of reduced thickness forms an integral hinge for the rectangular portion, a bent-up part of the rectangular portion along the edge parallel to the first-mentioned edge, which bent-up part is depressed to operate the switch, a pair of arms each extending along one of the other pair of edges of the rectangular portion from adjacent the bent-up part to a region on the supporting structure part-way along the length of the rectangular portion, and electrical contact means under the bentup portion of the rectangular portion and adapted to be operated when the push-button is depressed, the resilience of the hinge and the arms assist in the resoration of the depressed button when it is released.

4. A push-button switch as claimed in claim 3, and wherein the contact means consists of a dome-like part of a rubber or rubberlike material raised towards the rectangular portion, a disc of an electrically conductive material in said dome, which disc is pushed onto stationary electrical contacts to complete a connection when the button is depressed, the resilience of the dome facilitating reset on release of the button.

5. An electrical keypad having a number of switches each as claimed in claim 4, wherein the push-buttons and their supporting structure are an integral frame-like member and wherein the domes for all push-buttons are formed on a single sheet-like member.

6. An electrical keypad as claimed in claim 5, and which has a thin rubber-like sheet between the said supporting structure and the sheet carrying the domes.

7. An electrical push-button switch substantially as described with reference to Figs.

1, 2 and 3 or Fig. 4 of the accompanying drawings.

8. An electrical keypad substantially as described with reference to Fig. 4 of the accompanying drawings.