GB2087154A

GB2087154A - Keypad button

Info

Publication number: GB2087154A
Application number: GB8035346A
Authority: GB
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1980-11-04
Filing date: 1980-11-04
Publication date: 1982-05-19
Also published as: GB2087154B

Abstract

In a multi-push-button keypad, e.g. for use in a telephone set, the operating members are each formed by a double-ended member (13) which is centrally pivotted by means of a hinge (18) formed integral with the member (13) and a supporting frame. Each such member (13) is also linked to the frame by side-arms (19) each extending from a point near the end of a double-ended member to a point near the integral hinge (18). Below each end of each member (13) is a dimple (24) of a dimple pad 23, each dimple (24) of which has inside it a conductive member or is itself conductive. When a member (13) is depressed it rocks about its integral hinge (18) and collapses the appropriate dimple (24) to move its conductive part into engagement with electrical conductors or a printed circuit board located below the dimple pad (23). On release the member (13) is reset by resilience of the integral hinge (18) and the supporting arms (19), plus the resilience of the dimple (24). <IMAGE>

Description

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

A recent development in the field of such manually operable switching is the use of a so-called rubber (or rubber-like material) which is a sheet of rubber (or rubber-like material) with a dimple per pushbutton position. Each such dimple is a dome on the sheet surface which has on its concave surface a region of conductive material, e.g. metal or conductive plastics or rubber. 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 region 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 invention is to produce a simple and inexpensive push-button keypad using such dimple switches, although the arrangement can be used with other forms of switch.

According to the present invention there is provided a push-button switching arrangement, in which the push-buttons used for controlling electrical contact operations are made in pairs, with each said pair formed by a centrally pivotted, doubleended member of an electrically insulating material, in which the central pivot for a said pair of pushbuttons is formed by an integral hinge between the central region of the said generally double-ended member and a supporting frame also of said insulating material, in which when in use electrical contact means is located adjacent to each end region of a said generally double-ended member so as to be operated when a said end of that member is depressed, and in which the resilience of the insulating material assists in the restoration of a said operated push-button to rest when that button is released.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure lisa top plan view of one end of a telephone keypad embodying the invention, in which three different push-button shapes are shown although in practice one keypad would have all of its push-buttons the same; Figure 2 is a cross-section of part of Figure 1, taken along the line ll-ll; Figure 3 is a cross-section of part of Figure 1, taken along the line Ill-Ill; Figure 4 is a view of part of Figure 3, looking in the direction of the arrow IV-IV; Figure 5 is a perspective, exploded, view of a keypad embodying the invention.

Referring first to Figures 1 to 4, the keypad's push-buttons are moulded with, and thus integral with a rectangular frame 10 carrying push-buttons for 4x3 keypad. There are horizontal and vertical cross-pieces such as 11, 12 extending between the edges of the frame, which define six cut outs in the frame.

Each of these cut-outs is occupied by a pair of push-buttons with each such pair formed by a centrally-pivotted double-ended member such as 13, 14, 15. Member 13 is a rectangular member with a set of parallel grooves 16 at each end, member 14 is generally rectangular with two raised portions such as 17, each with a rounded end, while member 15 is dumb-bell shaped in plan. As will be seen, in these examples the digits identifying the keys are each marked on the push-button.

Each double-ended member is linked to the frame buy a central integral hinge portion 18 to the frame. In addition, each double-ended member has its ends linked by arms 19, 19, to the frame at or near to the integral hinge. Thus when one end of a push-button is depressed, it moves against the resilience of the arms and the integral hinge, so that on release this resilience helps to restore the member to its nonoperated state.

In Figure 5, the frame carries push-buttons which are similar to those shown at 13 in Figure 1, except that the number of grooves on each push-button differs. Hence we see the arms 19, and one hinge.

Each double push-button projects through a hole in a cover plate 22. Below the cover plate 22 and the push-button frame there is a dimple pad 23 of the type referred to above, with a dimple such as 24 below each of the push-buttons.

When a push-button is depressed it pivots about its central hinge and its supporting arms, and its under-most end such as 25, Figure 3, bears on one of the dimples. This dimple therefore collapses so that the conductive member inside it is brought into engagement with conductive tracks on a printed circuit board (not shown) located below the pad 23.

On release of the button its reset is effected by the resilience of the "squashed" dimple and of the material from which the frame and the buttons are made.

Thus we have a single one-piece moulding which provides all twelve push-buttons and the supporting frame, which are cheap to make. In the arrangement described, the numerals are marked on the keys - it will be appreciated that this could be done by moulding the numerals on the keys.

Note that the metal discs in the dimples can be replaced by other forms of conductive pads, e.g. of non-metallic conductive material. In fact the whole dimple pad can be of conductive material, in which case it would be separated from the contacts by a suitable insulating mask.

1. A push-button switcing arrangement, in which the push-buttons used for controlling electrical contact operations are made in pairs, with each said pair formed by a centrally pivotted, double-ended member in which the central pivot for a said pair of push-buttons is formed by an integral hinge be

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Keypad button This invention relates to the construction of electrical push-button operated switches, especially but not exclusively for use in telephone instruments. A recent development in the field of such manually operable switching is the use of a so-called rubber (or rubber-like material) which is a sheet of rubber (or rubber-like material) with a dimple per pushbutton position. Each such dimple is a dome on the sheet surface which has on its concave surface a region of conductive material, e.g. metal or conductive plastics or rubber. 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 region 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 invention is to produce a simple and inexpensive push-button keypad using such dimple switches, although the arrangement can be used with other forms of switch. According to the present invention there is provided a push-button switching arrangement, in which the push-buttons used for controlling electrical contact operations are made in pairs, with each said pair formed by a centrally pivotted, doubleended member of an electrically insulating material, in which the central pivot for a said pair of pushbuttons is formed by an integral hinge between the central region of the said generally double-ended member and a supporting frame also of said insulating material, in which when in use electrical contact means is located adjacent to each end region of a said generally double-ended member so as to be operated when a said end of that member is depressed, and in which the resilience of the insulating material assists in the restoration of a said operated push-button to rest when that button is released. Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure lisa top plan view of one end of a telephone keypad embodying the invention, in which three different push-button shapes are shown although in practice one keypad would have all of its push-buttons the same; Figure 2 is a cross-section of part of Figure 1, taken along the line ll-ll; Figure 3 is a cross-section of part of Figure 1, taken along the line Ill-Ill; Figure 4 is a view of part of Figure 3, looking in the direction of the arrow IV-IV; Figure 5 is a perspective, exploded, view of a keypad embodying the invention. Referring first to Figures 1 to 4, the keypad's push-buttons are moulded with, and thus integral with a rectangular frame 10 carrying push-buttons for 4x3 keypad. There are horizontal and vertical cross-pieces such as 11, 12 extending between the edges of the frame, which define six cut outs in the frame. Each of these cut-outs is occupied by a pair of push-buttons with each such pair formed by a centrally-pivotted double-ended member such as 13, 14, 15. Member 13 is a rectangular member with a set of parallel grooves 16 at each end, member 14 is generally rectangular with two raised portions such as 17, each with a rounded end, while member 15 is dumb-bell shaped in plan. As will be seen, in these examples the digits identifying the keys are each marked on the push-button. Each double-ended member is linked to the frame buy a central integral hinge portion 18 to the frame. In addition, each double-ended member has its ends linked by arms 19, 19, to the frame at or near to the integral hinge. Thus when one end of a push-button is depressed, it moves against the resilience of the arms and the integral hinge, so that on release this resilience helps to restore the member to its nonoperated state. In Figure 5, the frame carries push-buttons which are similar to those shown at 13 in Figure 1, except that the number of grooves on each push-button differs. Hence we see the arms 19, and one hinge. Each double push-button projects through a hole in a cover plate 22. Below the cover plate 22 and the push-button frame there is a dimple pad 23 of the type referred to above, with a dimple such as 24 below each of the push-buttons. When a push-button is depressed it pivots about its central hinge and its supporting arms, and its under-most end such as 25, Figure 3, bears on one of the dimples. This dimple therefore collapses so that the conductive member inside it is brought into engagement with conductive tracks on a printed circuit board (not shown) located below the pad 23. On release of the button its reset is effected by the resilience of the "squashed" dimple and of the material from which the frame and the buttons are made. Thus we have a single one-piece moulding which provides all twelve push-buttons and the supporting frame, which are cheap to make. In the arrangement described, the numerals are marked on the keys - it will be appreciated that this could be done by moulding the numerals on the keys. Note that the metal discs in the dimples can be replaced by other forms of conductive pads, e.g. of non-metallic conductive material. In fact the whole dimple pad can be of conductive material, in which case it would be separated from the contacts by a suitable insulating mask. CLAIMS

1. A push-button switcing arrangement, in which the push-buttons used for controlling electrical contact operations are made in pairs, with each said pair formed by a centrally pivotted, double-ended member in which the central pivot for a said pair of push-buttons is formed by an integral hinge be tween the central region of the said double-ended member and a supporting frame in which when in use electrical contact means is located adjacent to each end region of a said double-ended member so as to be operated when a said end ofthat member is depressed, and in which the resilience of the material assists in the restoration of a said operated push-button to rest when that button is released.

2. A push-button switching arrangement, in which the push-buttons used for controlling electrical contact operations are made in pairs with each said pair formed by a centrally-pivotted, doubleedged member of an electrically insulating material, in which the central pivot for a said pair of 'pushbuttons' is formed by an integral hinge between the central region ofthe said double-ended member and a supporting frame also of said insulating material, in which when in use electrical contact means is located adjacentto each end region of a said double-ended member so as to be operated when a said end of that member is depressed, and in which the resilience of the insulating material assists in the restriction of a said operated push-button to rest when that button is released.

3. An arrangement as claimed in claim 1 or 2, in which supporting arms each of which is roughly parallel to the length of a said double-ended member each extend from the ends of a said member to a point on the supporting frame adjacent to the integral hinge.

4. An arrangement as claimed in claim 1,2 or 3, and in which said contact means includes a sheet of rubber or rubber-like material with for each said push-button a dome facing the push-button, a disc of an electrically conductive material in said dome, and electrical conductors on a printed circuit board below the dome, so that when a push-button is depressed its under-surface collapses on said dome to cause a contact making operation.

5. A push-button switching arrangement substantially as described with reference to the accompanying drawings.