GB2023933A - Push button switch - Google Patents

Abstract

A push button switch which includes two leaf springs 22,24 providing on operation a make operation. By provision of shoulder portions 36,38 the switching action provides tactile feedback as shoulders 32,34 of a recess 30 of the button 10 engage and move over the shoulder portions 36,38. <IMAGE>

Description

SPECIFICATION Improvements in or relating to push button switches The present invention relates to push button switches and more particularly to push button switches for telephones.

The present invention provides a push button switch for a telephone subscribers instrument including a push button which is spring urged towards a first position, a pair of co-operating leaf spring contacts mounted so as to be spring urged apart in the first position of the push button, in which each leaf spring contact has a shoulder portion which is engageable by a portion of the push button during depression of the push button to cause in a second position of the push button the co-operating leaf spring contacts to make.

In a preferred embodiment the push button is cylindrical in shape with a hollow cylindrical shaped internal recess in which the pair of leaf spring contacts is positioned. The portion of the push button may comprise the edge of the internal recess.

In this embodiment the push button is provided with an annular shaped internal recess concentric with and surrounding the cylindrical shaped internal recess, a coil spring being mounted in the annular shaped internal recess to provide urging of the push button.

The push button is preferably retained in its first position with respect to the pair of leaf spring contacts by retaining lugs formed integrally with the push button, the retaining lugs co-operating with a base board on which the pair of leaf spring contacts are mounted.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in cross sectional elevation a push button mechanism according to the present invention, Figure 2 shows the push button mechanism of Figure 1 in plan view along the line A-A and, Figure 3 shows the push button mechanism of Figure 1 in partial cross section along the line C-C.

Referring now to the drawings there is shown a push button 10 which is spring urged upwards buy a spring 12. The push button is retained by lugs 14, 16 into a base housing member comprising two portions 18,20. The portion 18 retains co-operating leaf springs 22, 24 which in the non-operated position of the push button switch are held apart by being spring urged against the sides 26, 28 of a cavity 30 within the push button 10. The cavity 30 is formed with shoulder portions 32, 24 which in operation of the push button co-operate with shoulders 36, 38 on respective leaf springs 22, 24.

In operation the push button 10 is depressed and is spring urged against this depression by spring 12.

Initially the sides 26, 28 of cavity 30 will slide easily against the leaf spring 24,22 until the shoulder portions 36, 38 meet the shoulder portions 32, 24.

There will then be increased resistance to further depression of the push button which will be felt by the operator of the push button. To overcome this increased resistance the operator is required to increase the pressure applied to the push button to overcome the resistance of the shoulders 36,38.

When this resistance is overcome the leaf springs 22, 24 will move rapidly together causing contacts 40, 42 to make.

The push button therefore, has a tactile feedback action which makes non-operation of the push button virtually impossible.

As may be seen the push button switch unit is, by virtue of its sliding action partially sealed against ingress of dust into the contact area.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation in its scope.

1. A push button switch for a telephone subscribers instrument including a push button which is spring urged towards a first position, a pair of co-operating leaf spring contacts mounted so as to be spring urged apart in the first position of the push button, in which each leaf spring contact has a shoulder portion, which is engageable by a portion ofthe push button during depression ofthe push button to cause in a second position of the push button the co-operating leaf spring contacts to make.

2. A push button switch as claimed in claim 1 in which the push button is cylindrical in shape with a hollow cylindrical shaped internal recess into which the pair of leaf spring contacts is adapted to project.

3. A push button switch as claimed in claim 2 in which the portion of the push button comprises the edge of the internal recess.

4. A push button switch as claimed in claim 2 in which the push button is provided with an annular shaped internal recess concentric with and surrounding the cylindrical shaped internal recess.

5. A push button switch as claimed in claim 4 in which a coil spring is mounted in the anular shaped internal recess to provide the spring urging of the push button.

6. A push button as claimed in any preceding claim in which the push button is retained in its first position with respect to the pair of leaf spring contacts by retaining lugs forward integrally with the push button, the retaining lugs co-operating with a base board.

7. A push button switch as claimed in claim 6 in which the pair of leaf spring contacts is mounted in the base board.

8. A push button switch as claimed in claim 6 in which the pair of leaf spring contacts projects substantially perpendicularly from the base board.

9. A push button switch as claimed in any preceding claim in which a degree of movement of the push button is permitted before the portion of the push button contacts the shoulder portion of each leaf spring contact, increased pressure being required to cause the push button to move into its second position in which the leaf spring contacts make, whereby to provide a tactile feedback action.

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

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to push button switches The present invention relates to push button switches and more particularly to push button switches for telephones. The present invention provides a push button switch for a telephone subscribers instrument including a push button which is spring urged towards a first position, a pair of co-operating leaf spring contacts mounted so as to be spring urged apart in the first position of the push button, in which each leaf spring contact has a shoulder portion which is engageable by a portion of the push button during depression of the push button to cause in a second position of the push button the co-operating leaf spring contacts to make. In a preferred embodiment the push button is cylindrical in shape with a hollow cylindrical shaped internal recess in which the pair of leaf spring contacts is positioned. The portion of the push button may comprise the edge of the internal recess. In this embodiment the push button is provided with an annular shaped internal recess concentric with and surrounding the cylindrical shaped internal recess, a coil spring being mounted in the annular shaped internal recess to provide urging of the push button. The push button is preferably retained in its first position with respect to the pair of leaf spring contacts by retaining lugs formed integrally with the push button, the retaining lugs co-operating with a base board on which the pair of leaf spring contacts are mounted. Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in cross sectional elevation a push button mechanism according to the present invention, Figure 2 shows the push button mechanism of Figure 1 in plan view along the line A-A and, Figure 3 shows the push button mechanism of Figure 1 in partial cross section along the line C-C. Referring now to the drawings there is shown a push button 10 which is spring urged upwards buy a spring 12. The push button is retained by lugs 14, 16 into a base housing member comprising two portions 18,20. The portion 18 retains co-operating leaf springs 22, 24 which in the non-operated position of the push button switch are held apart by being spring urged against the sides 26, 28 of a cavity 30 within the push button 10. The cavity 30 is formed with shoulder portions 32, 24 which in operation of the push button co-operate with shoulders 36, 38 on respective leaf springs 22, 24. In operation the push button 10 is depressed and is spring urged against this depression by spring 12. Initially the sides 26, 28 of cavity 30 will slide easily against the leaf spring 24,22 until the shoulder portions 36, 38 meet the shoulder portions 32, 24. There will then be increased resistance to further depression of the push button which will be felt by the operator of the push button. To overcome this increased resistance the operator is required to increase the pressure applied to the push button to overcome the resistance of the shoulders 36,38. When this resistance is overcome the leaf springs 22, 24 will move rapidly together causing contacts 40, 42 to make. The push button therefore, has a tactile feedback action which makes non-operation of the push button virtually impossible. As may be seen the push button switch unit is, by virtue of its sliding action partially sealed against ingress of dust into the contact area. It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation in its scope. CLAIMS

1. A push button switch for a telephone subscribers instrument including a push button which is spring urged towards a first position, a pair of co-operating leaf spring contacts mounted so as to be spring urged apart in the first position of the push button, in which each leaf spring contact has a shoulder portion, which is engageable by a portion ofthe push button during depression ofthe push button to cause in a second position of the push button the co-operating leaf spring contacts to make.

2. A push button switch as claimed in claim 1 in which the push button is cylindrical in shape with a hollow cylindrical shaped internal recess into which the pair of leaf spring contacts is adapted to project.

3. A push button switch as claimed in claim 2 in which the portion of the push button comprises the edge of the internal recess.

4. A push button switch as claimed in claim 2 in which the push button is provided with an annular shaped internal recess concentric with and surrounding the cylindrical shaped internal recess.

5. A push button switch as claimed in claim 4 in which a coil spring is mounted in the anular shaped internal recess to provide the spring urging of the push button.

6. A push button as claimed in any preceding claim in which the push button is retained in its first position with respect to the pair of leaf spring contacts by retaining lugs forward integrally with the push button, the retaining lugs co-operating with a base board.

7. A push button switch as claimed in claim 6 in which the pair of leaf spring contacts is mounted in the base board.

8. A push button switch as claimed in claim 6 in which the pair of leaf spring contacts projects substantially perpendicularly from the base board.

9. A push button switch as claimed in any preceding claim in which a degree of movement of the push button is permitted before the portion of the push button contacts the shoulder portion of each leaf spring contact, increased pressure being required to cause the push button to move into its second position in which the leaf spring contacts make, whereby to provide a tactile feedback action.

10. A push button switch for a telephone subscribers instrument constructed and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.