GB2239629A - Keys for keypads - Google Patents

Abstract

A push-button array is produced by moulding a row of buttons (11, 12, 13) with integral flexible connections (19, 23) therebetween, mounting the buttons by supporting the connections at points (23) between the buttons. As shown, there is a multiple row array of elongated buttons (11-13) which are angled with respect to the direction of the rows, and the flexible interconnections are also oblique with respect to the row directions. The rows are interconnected by common carriers 33, 34. <IMAGE>

Description

Title: "Push-button array and method of manufacturing same" Description of the Invention The present invention relates to a push-button array comprising a plurality of rows of buttons. Such arrays are commonly used in electronically operated apparatus to enable a user to apply instructions or data to the apparatus. Typically, the pushbuttons are marked with numerals or letters to identify them.

It is generally considered desirable to reduce the size of electronically operated apparatus. This is particularly so in the case of portable apparatus which is intended to be used in different places and carried between these places.

There is, accordingly, a requirement for relatively small push-button arrays. This requirement conflicts with the trend to provide a larger number of push-buttons in the array, in order that instructions or data can be applied more conveniently or in order that the apparatus can be more versatile. An example is a telephone hand-set which is required to have ten push-buttons designated by the numerals 0 - 9 and further push-buttons corresponding to different functions of the hand-set. As the functional versatility of hand-sets is increased, it is either necessary to use each of a small number of push-buttons to represent two or more different functions or to increase the number of push-buttons in the array.

The conflicting requirements of minimising size and increasing the number of push-buttons in an array leads to a number of problems. These include physical crowding of the push-buttons so that the user has difficulty in entering instructions or data correctly, providing buttons of adequate size, mounting of the buttons in the array and controlling the location of the buttons.

It has been proposed that the buttons of an array should be moulded integrally with one another and with connecting portions of the moulding which extend between adjacent buttons but are flexible so that relative movement of adjacent buttons is possible.

This arrangement provides that one button is located by the connecting portion of the moulding relative to an adjacent button.

Buttons at the ends of the rows can be located by further connecting portions of the moulding with the buttons at the ends of other rows so that all buttons of the array are comprised by a single moulding. The proposed arrangement would provide satisfactory location of the individual buttons. However, it is also important that when one button of the array is pressed, adjacent buttons should not move significantly. The proposed arrangement would not provide sufficient mechanical isolation of adjacent buttons to ensure that erroneous signals would not be provided when one button of the array is pressed.

It is desirable to include, in a die for moulding plastics push-buttons, a runner and gate for each button, the gate communicating directly with the cavity which defines the button to be formed. If each button is not provided with its runner and gate, then the quality of that surface of the button which is to be exposed in use, and which is required to bear a numeral or letter, is likely to be inferior. The proposed integral array cannot be formed in this way, because of the proximity of the cavities which corresond to individual buttons. The difficulty can be overcome by feeding the plastics composition to certain of the cavities through those parts of the die which define the connecting portions of the array but this would result in the surface finish form or of some buttons being inferior to that of other buttons.

According to a first aspect of the present invention, there is provided a method of forming a push-button array comprising a plurality of rows of buttons, each row including at least three buttons, wherein there is prepared a mould defining a cavity which includes three mutually spaced larger portions, corresponding to three buttons of a row, and four smaller portions, one of which communicates with both a first and second of said larger portions, another of which smaller portions communicates with both the second and a third of said larger portions and the remaining two of which smaller portions communicate with the first and third larger portions respectively, a plastics composition is injected concurrently into said three larger portions of the cavity, the plastics composition flows from the larger portions into said smaller portions of the cavity to form a moulding which includes three buttons forming a row, two limbs extending between adjacent buttons of the row and two further limbs extending from first and third buttons of the row, there are produced in a corresponding way a number of further mouldings, each comprising a row of buttons and limbs extending between the buttons and extending from first and third buttons, and a plurality of said mouldings are attached to a common carrier to form the array.

Mouldings of different colours may be incorporated in a single array. A single moulding may incorporate differently coloured materials, for example legends of one colour incorporated in buttons formed mainly of material having a different colour.

The mouldings may be attached to the carrier by welding, by bonding and/or interfitting mechanical formations.

According to a second aspect of the invention, there is provided a push-button array comprising a plurality of rows of moulded plastics buttons wherein each row comprises a plurality of buttons, mutually adjacent buttons of the row are connected to each other by a limb which is moulded integrally with the buttons and wherein a mid-portion of the limb rests on a support, relative to which the majority of the buttons of the array are required to remain substantially stationary when one button is pressed.

The provision of a stationary support for a mid-portion of a limb extending between adjacent buttons substantially eliminates the risk of movement of one button being transmitted to an adjacent button when the one button only is pressed.

According to a third aspect of the invention, there is provided a push-button array comprising a plurality of rows of buttons, each row including at least three buttons, wherein each button is elongated and is arranged with its length inclined at an acute angle to the length of its row, wherein mutually adjacent buttons of the row are united with each other by a limb which is moulded integrally with the buttons, wherein the limb includes distinct end portions and an elongated intermediate portion, wherein the intermediate portion is arranged with its length inclined at an acute angle to the lengths of the adjacent buttons, wherein the end portions are elongated and wherein the length of each end portion exceeds the minimum separation of the intermediate portion from each adjacent button.

The second and third aspects of the invention are preferably used in combination with each other.

An example of an array embodying the second and third aspects of the invention and which is manufactured by a method according to the first aspect of the invention will now be described, with reference to the accompanying drawing, which illustrates a plan view of a part of a push-button array.

The array illustrated in the drawing is a rectangular array and comprises a number of rows of push-buttons, one of which rows is identified by the reference numeral 10. The rows are rectilinear and are mutually parallel. The number of push-buttons in each row is the same as the number in each other row and the push-buttons are arranged in mutually parallel columns. The length of each column is perpendicular to the length of each row. In the example illustrated, all of the buttons have the same size and shape. The buttons of one row may differ in colour from buttons of another row.

The row 10 comprises three buttons and these are identified in the drawing by the reference numerals 11, 12 and 13. These buttons are elongated and are arranged with their respective lengths inclined at an acute angle to the length of the row and to the length of each column of buttons. Each of the buttons illustrated in the drawing has a pair of opposite, rectilinear, longer sides 14,15 and a pair of opposite, curved, shorter boundaries 16,17 hereinafter called ends. The buttons are hollow and are open at their undersides. Each button has a peripheral flange 18 which is adjacent to the underside of the button. The upper surface of each button may be substantially flat or may be convex.

For clarity of illustration, the size of buttons, relative to the length of the row, is reduced in the drawing, so exaggerating the spacing between the buttons.

The buttons 11 and 12 are connected together by a limb 19 which has a small volume, as compared with the volume of each button. The limb 19 is united with the button 11 at a position midway along its side 14 and is united with the button 12 at a position mid-way along the side 15 of that button. The limb is united with the buttons 11 and 12 at the flanges thereof and the thickness of the limb, at least where it joins the flanges, is preferably the same as the thickness of the flanges. The limb is thus spaced from the upper surface of each button by a distance approximately equal to the depth of the button. The width of the limb 19 may exceed the thickness of the limb but is small, as compared with the length of the rectilinear side 14 of the button.

The limb 19 comprises a first, elongated, rectilinear end portion 20 which is adjacent to the button 11 and is perpendicular to the length of that button. The limb includes a second, elongated, rectilinear end portion 21 which is adjacent to the button 15 and is perpendicular to the length of that button. The limb 19 further comprises a rectilinear, elongated intermediate portion 22. The length of the intermediate portion is inclined at an acute angle to the lengths of the buttons 11 and 12, is also inclined to the length of the row 10 and is inclined at an angle of less than 900 to the end portions 20 and 21.

The end portions 20 and 21 of the limb 19 are of the same length and this length exceeds the minimum separation between the intermediate portion 22 of the limb and each of the buttons 11 and 12. This minimum separation is represented in the drawing at a. - The buttons 12 and 13 are connected together by a limb 23 which is identical with the limb 19 and which is arranged in a manner corresponding to that in which the limb 19 is arranged. The intermediate portions of the limbs 19 and 23 are mutually parallel.

A further limb 25 extends from the button 11 in a direction away from the button 12. The limb 25 includes a first end portion 26 which is identical with the end portion 21 and a further end portion 27 which, in the example illustrated, includes an annulus.

The limb 25 also includes an intermediate portion 28 which is elongated, rectilinear and parallel to the intermediate portion 22.

The portion 28 is, however, somewhat shorter than the intermediate portion 22, typically having a length which is one half of the length of the portion 22. The end portion 26 joins the button 11 at the flange 18 thereof.

A further limb 29 extends from the button 13 in a direction away from the button 12. The limb 29 comprises an end portion which is identical with the end portion 20 and which joins the button 13 at the flange thereof. The limb 29 has a further end portion 31 which includes an annulus and has an intermediate portion 32 corresponding to the intermediate portion 28.

The row of buttons 10 is formed by moulding a plastics material in a die cavity having respective portions which define the buttons 11, 12 and 13, the limbs 19 and 23 and the limbs 25 and 29.

Accordingly, these limbs and the three buttons are integral one with the other. It will be noted that the volume of each button is considerably greater than is the volume of each limb. The die includes a respective runner and gate communicating with each of the larger cavities corresponding to the buttons 11, 12 and 13. The plastics composition is injected into the mould cavity through these gates and flows from the larger cavities into the smaller cavities which form the limbs. The plastics material in each of the larger cavities is subjected to the full injection pressure and this enables those surfaces of the buttons which will be the exposed surfaces during use to be formed to the required size and shape within fine tolerance limits and ensures that a high quality surface finish is achieved on the surfaces of the buttons.

After moulding, the row of buttons 10 is assembled with a pair of carriers, one adjacent to each end of the row. Further rows of buttons are assembled with the carriers 33 and 34 in the same manner. The rows of buttons being spaced apart along the carriers.

For receiving the end portion 27, the carrier 33 has a formation which interfits mechanically with that end portion. Thus, in the example illustrated, the carrier has a cylindrical spigot which can be received with an interference fit in the end portion 27. The carrier 34 has a corresponding spigot which is received with an interference fit in the end portion 31. The end portions are secured to the carriers by welding or by bonding. The carriers 33 and 34 may be mouldings of a plastics composition which is used to form the row of buttons 10.

It will be understood that other mechanically interfitting formations may be provided at the ends of the rows and on the carriers and that, in a case where the rows of buttons are welded to the carriers, mechanically interfitting formations may be avoided if a suitable jig is used to hold the components of the array in the required positions during welding.

For use, the push-button array is mounted in a housing having an array of apertures, through each of which one of the push-buttons protrudes. The flanges 18 and the limbs connecting the buttons of each row to each other lie concealed beneath a top wall of the housing. The housing further comprises a number of supports, one engaged with a mid-portion of each of the limbs extending between adjacent buttons. The position of one of these supports is indicated at 35 in the drawing. The supports are fixed with respect to the top wall of the housing and each support engages the corresponding intermediate portion only at the centre of that intermediate portion so that flexing of the intermediate portion is not significantly inhibited. When one button of the array is pressed, that button can move downwardly within its aperture in the top wall of the housing.The immediately adjacent parts of the limbs flex to accommodate that movement but more distant parts of the limbs remain stationary so that the adjacent buttons are not disturbed. It will be understood that there would be associated with each button electrical contacts or other means for providing an electrical signal when the button is pressed. Spring-loading additional to the limbs of the array may be provided for urging each button towards its projected position.

It will be appreciated that the number of buttons in a row may be increased beyond three and could be reduced.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (6)

CLAIMS:

1. A push-button array comprising a row of moulded plastics buttons wherein each row comprises a plurality of buttons, mutually adjacent buttons of the row are connected to each other by a limb which is moulded integrally with the buttons and a mid-portion of the limb rests on a support, relative to which the majority of the buttons of the array are required to remain substantially stationary when one button is pressed.

2. An array according to Claim 1 wherein said limb includes a first end portion projecting from one button in a first direction, a second end portion extending in the first direction to another button of the row and an intermediate portion which is inclined at an acute angle to both of the end portions.

3. A push-button assembly comprising a plurality of rows of buttons, each row including at least three buttons, wherein each button is elongated and is arranged with its length inclined at an acute angle to the length of its row, wherein mutually adjacent buttons of the row are united with each other by a limb which is moulded integrally with the buttons, wherein the limbs include distinct end portions and an elongated intermediate portion, wherein the intermediate portion is arranged with its length inclined at an acute angle to the lengths of the adjacent buttons, wherein the end portions are elongated and wherein the length of each end portion exceeds the minimum separation of the intermediate portion from each adjacent button.

4. A method of forming a push-button array comprising a plurality of rows of buttons, each row including at least three buttons, wherein there is prepared a mould defining a cavity which includes three mutually spaced larger portions, corresponding to three buttons of a row, and four smaller portions, one of which communicates with both a first and a second of said larger portions, another of which communicates with both the second and a third of said larger portions and the remaining two of which communicate with the first and third larger portions respectively, a plastics composition in injected concurrently into said three larger portions of the cavity, the plastics composition flows from the larger portions into said smaller portions of the cavity to form a moulding which includes three buttons forming a row, two limbs extending between adjacent buttons of the row and two further limbs extending from first and third buttons of the row, there are produced in a corresponding way a number of further mouldings, each comprising a row of buttons and limbs extending between the buttons of the row and from buttons at the ends of the row and wherein a plurality of said mouldings are attached to a common carrier to form the array.

5. A push-button array substantially as herein described with reference to the accompanying drawing.

6. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.