IE54641B1 - An electro-mechanical switch for a telephone - Google Patents

Abstract

1. An electro-mechanical switch for telephone apparatus, comprising a base part (1) made of insulating material and in which contact springs (2) in the form of leaf springs are arranged one beside another in parallel spaced planes so as to cover one another as regards their outline, the contact springs being in each case firmly clamped in the base part (1) at one end (3) and at the other end (4) can be elastically deflected at right angles to their plane of orientation by means of a control slide (7) which is guided so as to be linearly movable on the base part (1), characterised in that on the base part (1) the guide path of the control slide (7) is oriented parallel to the longitudinal direction of the contact springs (2) and the control slide (7) is provided with rigid, essentially parallel bars (8) which engage between the contact springs, parallel to the contact springs (2) from the deflectable ends thereof ; that on their side surfaces (11) which face towards the deflectable contact springs (2), the control bars (8) are in each case provided with both a sloped contact surface (13), which protrudes from the plane of the respective lateral surface, and also with a deflecting surface (12) which adjoins the contact surface and extends at a constant distance from the lateral starting plane (11) ; that in the vicinity of their free ends (4), the deflectable contact springs (2) are in each case provided with a driving cam (14) which protrudes at right angles to the deflecting surface (12) of the adjacent control bar (8), and have an elastic prestress (P1) which is oriented in the direction of the driving cam ; and that adjacent the free ends (4) of the deflectable contact springs (2), in each case from the side of the deflecting surface (12) of the adjacent side surface of the control bar (8), a counter-contact (6) is provided which has a parallel-extending, rigid contact surface and is fixed to the base part (1).

Description

The invention relates to an electro-mechanical switch for a telephone comprising a base member made of insulating material in which is held one end of each of a plurality of leaf springs whose free ends carry contacts so that deflection of the free ends by means of a control member causes making and breaking of contact with associated contacts held in the base member.

Switdies of this kind are used as telephone cradle switches which are operable between two positions - generally using the weight of a handset which is to be lifted off the cradle for operation of the telephone. The control member which effects the operation of the contact is generally arranged so as to be movable at right angles to the parallel planes of the deflectable contact leaf springs, i.e. the control 'member is movable parallel to the direction of deflection of the leaf springs. The operating movement can be transmitted for example by means of the handset via longitudinally movable members, which extend into the telephone housing, to an operating rocker which is pivotally mounted on the base member of the switch from where the movement is transmitted to the control member.

The control member transmits the operating movement via carrier cams projecting from its flat side surface directly to the free end portions of the deflectable contact leaf springs which free end portions extend at right angles to the flat side surface and are respectively assigned to the cams.

It is also known to combine cradle switches with additional contact arrangements for various switching functions e.g. in devices offering increased operating comfort. For satisfactory co-operation of the contact arrangements in the overall circuit it is generally necessary for functional reasons to adhere strictly to a predetermined sequence of operating the contacts when changing the switch position.

A predetermined time flow of the switching sequence can be achieved by an appropriate spatial arrangement of the individual contacts in series with one another along the length of the overall operating range of the control member.

If the control ir.embef is movable parallel to the deflection direction of the contact leaf springs then a contact leaf spring which has reached its range of effective deflection right at the beginning of the operating movement range, (i.e. the leaf spring has been deflected into its operating position, and has been moved for example from its initial state open contact into the state closed contact) will continue to be moved by the control member beyond its operating position until the end of the operating movement range is reached. In this case the counter-contact which cooperates with the leaf spring contact must not be held rigid but must likewise be deflectable as indirectly it too is moved beyond its operating position by the contact leaf spring which is driven by the control member where the operating position of the cooperating contact elements naturally remains unchanged.

If the operation of the other contacts is arranged to be spatially staggered following the first contact - operation in the operating movement range of the control member, then with a similar stagger an increasing number of already actuated pairs of contacts must in turn be resiliently moved beyond their operating positions, and in the end positions the first actuated pair of contacts is finally deflected furthest beyond its actual operating position, the second pair of contacts is deflected somewhat less far and so on. .This means that the operating force which is to be overcome by the weight of the replaced handset over the operating movement range increases in stepped fashion in accordance with the staggered deflection of the contact leaf springs and indeed increases substantially beyond the force actually needed for the function. In switches comprising variable contact construction which differ in size, this occasionally results in an interference factor which influences the switching reliability to a greater or lesser extent.

It is an aim of the invention to improve upon a switch of the above-described type in such manner as to avoid a deflection which exceeds the essential operating movement of the particular cooperating contact elements in spite of the fact that the operating sequence of the individual switching contacts can be contrived to be staggered over the operating movement range of the control member.

Here essential operating movement of the cooperating contact elements is to be understood as the operating movement range of the deflectable contact leaf springs from a closed contact position with an overrange margin which safeguards adequate contact force to a position which is sufficiently widely open for electrical functioning reliability.

According to this invention there is provided an electro-mechanical switch for telephone apparatus, comprising a base part made of insulating material and in which contact springs in the form of leaf springe are arranged one beside another in parallel spaced planes so as to cover one another as regards their outline, the contact springs being in each case firmly clamped in the base part at one end and at the other end can be elastically deflected at right angles to their plane of orientation by means of a control slide which is guided so as to be linearly movable on the base part, on the base part the guide path of the control slide being oriented parallel to the longitudinal direction of the contact springs and the control slide being provided with rigid, essentially parallel bars which engage between the contact springe, parallel to the contact springs from the deflectable ends thereof; on their side surfaces which face towards the deflectable contact 6 4 1 springs, the control bars being in each case provided with both a sloped contact surface, which protrudes from the plane of the respective lateral surface, and also with a deflecting surface which adjoins the contact surface and extends at a constant distance from the lateral starting plane; in the vicinity of their free ends, the deflectable contact springs being in each case provided with a driving cam which protrudes at right angles to the deflecting surface of the adjacent control bar, and having an elastic prestress which is oriented in the direction of the driving cam; and adjacent the free ends of the deflectable contact springs, in each case from the side of the deflecting surface of the adjacent side surface of the control bar, a counter-contact being provided which has a parallel-extending, rigid contact surface and is fixed to the base part.

Preferably the driving cams of the deflectable contact springs are in each case formed as a V-shaped shoulder which is oriented at right angles to the plane of the spring and at right angles to the length of the spring.

Conveniently it may be arranged that at their two end zones, the parallel bars of the control slide are rigidly connected to one another by means of a beam-like cross-piece which is oriented at right angles to the 4 6 11 length of the bars. In this latter case it may be provided that bars and cross-beams of the control slide have a profile which ie essentially rectangular. In this latter case it may be arranged that one of the cross-beams of the control slide has at least one opening which is oriented at right angles to the length ot the bars and cross-beams and serves to engage a driving pin of an actuating element which is pivotable on the base part.

Advantageoualy it may be that the rigid contact surfaces which are provided as counter-contacts, are limited, as far as their length is concerned, to the length of the free end region of the deflectable contact springe behind the driving cam. In this case it is possible that a flat conductor strip which is bent at right angles is attached to the contact surfaces, which are provided as counter-contacts, said conductor strip in the situation when it is placed on the bottom plane of the base part is positioned parallel to the flat springs which constitute the deflectable contact springs, and bo as to function properly by means of structural elements which protrude from the flat contact surface of the bottom plane, said conductor strip at its end facing away from the contact surface changing into a connecting tag, by means of which it protrudes vertically from one of the outer boundary surfaces of the base part. Conveniently it may be that two contact surfaces which serve as counter-contacts, are in each case formed as parallel fins of a U-profile; and that the base of the profile which extends at right angles thereto, represents the output plane of a common conductor strip which changes into the connecting tag.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a telephone switching device embodying this invention; Fig. 2 is a schematic diagram of the switching device shown in Fig. 1 in a side view at 90° to the view shown in Fig. 1; Fig. 3 is a schematic diagram of a switching device forming a second embodiment of the invention; Fig. 4 is a schematic diagram of an embodiment of switching device for push-button actuation; and 4 6 4 1 Fig. 5 is a perspective exploded view of the switching device shown in Figs. 1 and 2.

Referring to Figs. 1,2 and 5 of the drawings the switching devices each possess a plurality of contact springs 2 in the form Of elongate, rectangular leaf springs arranged in spaced parallel planes so as to be aligned with one another in a base member 1 made of insulating material. These contact springs are each accommodated and held by one end 3 in a respective one of slots which run at right angles to the base plane 5 of the base member but at its other end portion 4 each leaf spring extends for a distance freely above the base plane of the base member and so can be elastically deflected at right angles to the spring plane.

The deflectable ends of the contact springs are assigned rigid abutments 6 in the form of parallel orientated contact surfaces. At the corresponding end portions 4 of the contact springs and of the abutments 6, wire-like contact elements (ribs) 31 are arranged with minimal contact resistance on the mutually facing spring surfaces. In order to achieve a staggered double contact function, in the region of its free end portion 4 each contact spring 2 is bifurcated with two symmetrical end strips separated by means of a slot 32 parallel to the spring length.

A control slide 7 serves to actuate the switching contact pairs each comprising a deflectable contact spring 2 and a rigid contact abutment 6. This control slide is accommodated in a guide path formed on the base member 1 so as to be movable between end positions in a rectilinear fashion parallel to the longitudinal direction of the contact springs. The control slide has rigid control crossbars 8 which engage in parallel between the contact springs. The guide path in the base member 1 is provided by slots 9 and guide rockers 10 (Fig. 1) between which the crossbars 8 of the slide 7 are accommodated so as to be axially movable with minimum play.

On two opposite side surfaces 11 of each crossbar, at positions adjacent the deflectable end portions 4 of adjacent contact springs 2, each control crossbar 8 is provided with parallel def le ction surfaces or lands 12 which project outwards from the planes of the respective side surfaces towards the contact springs and with inclined (at an angle to the lands 12 greater than 90°) abutting surfaces 13.

In the vicinity of their free end portions 4 the deflectable contact springs 2 are each provided with a drive cam portion 14 which projects towards the deflection surfaces or lands 12 of the adjacent control crossbar 8.

In this embodiment the cam consists of a V-shaped elbow of the spring.

The deflectable contact springs 2 are elastically biassed in the direction of the drive cam portions 14 (arrow Pl in Fig. 5)by means of which, in their rest position, they tend to maintain ohmic contact with the adjacent contact abutment 6 with adequate contact pressure.

The contact surfaces of the abutments 6 are 16 4 1 limited in length to the end portions 4 of the deflectable contact springs 2 beyond the drive cam portions 14 and have their free front edges 15 each inserted into a respective supporting slot 16 of a lateral boundary wall of the base member 1. A conductor strip 18 lies parallel with and on the base plane 5 of the base member 1 and has an end zone which provides a connecting lug 17. The strip 18 is arranged at right angles to the contact surface of the rigid abutment 6. The ronductor strip 18 can be fixed in a functionally accurate position by means of guide knobs 19 arranged on the surface of the base plane 5. The connecting lug 17, and likewise other connecting lugs provided at the fixed ends 3 of the deflectable contact springs, pass through the side wall of the base member which faces towards the circuit board 28 and allow direct ohmic connection of the switching device into the circuit board.

Two of the rigid contact surfaces of the abutments 6 can instead be designed (Fig. 5) as parallel fins or lugs of an integrally formed U-profile, where the base 34 of the O-profile forms the starting plane for the conductor strip 18 which in this case provides a common supply for both the contact surfaces and which extends in the normal manner into a connecting lug 17.

At their two end zones the parallel crossbars 8 of the control slide 7 are each rigidly connected by means of a strut like arm 20,21 running at right angles thereto.

The struts 20,21 and crossbars 8 have a predominantly rectangular crosssection. One of the struts 20 has its major surfaces parallel with the end surfaces of the crossbars. At the other ends of the crossbars, the second strut comprises an arm lying flat on upper sides of the cross5 bars.

For drive purposes this side arm 21 of the control slide is provided with an opening 22. A drive journal 23 can engage into this opening for transmission of the actuating movement. The drive journal 23 forms part of a switching rodcer 24 which is mounted so as to be pivotable over an angle a on bearing journals 33 on an outer surface of the base member between end stop positions and which switching rocker is biased by means of an energy store 25 (a spring) to one of its end stop positions.

The pivoting of the switching rocker 24 results in drive movement of the control slide via the coupling between the drive journal 23 and the opening 22. On the other hand the operating movement of the contact springs is determined by the difference in level between the starting plane of the side surfaces 11 of the control crossbars and the deflection surfaces or lands 12 which project therefrom.

In the switching device which is illustrated in Figs. 1 and 2 and in which the base plane 5 of the base member 1 is orientated at right angles to the circuit board 28, the switching rocker 24 which is pivotally mounted on the outer surface of the base member is shown in its upper end stop position. In this position it is held by the energy 546 11 store 25 which is in the form of a tension spring and which extends between the base member and the switching rocker.

On account of the form locking drive coupling between journal and opening, in this position of the rocker 24 the control slide 7 also occupies its upper end position which corresponds to the operating state handset removed.

The arrow F2 (Fig. 2) illustrates the direction in which a force must act in order to deflect the switching rocker which will also bring the control slide into its other end position in accordance with the state "handset replaced.

In the second embodiment of switching device which is illustrated in Fig. 3, the guide paths of the control slide 7' and the contact springs are orientated horizontally, lying parallel with and over the circuit board 28. An actuating force in the direction of the arrow P3, vertically and at right angles to the plane of the circuit board, and which is preferably applied as the weight of the handset, is in this case diverted by the crank form of the switching rocker 26 into a horizontal movement and is transmitted via the above mentioned coupling elements journal 23 and opening 22 to the control slide 7*.

In Fig. 3 the switching rocker is shown in a position which is loaded against the elastic force of an energy store 27 (compression spring) and which corresponds to the switching state handset replaced. When the load is relieved by removal of handset the spring 27 which extends between the control slide 7' and the base member 1' can move the control slide 7' in the direction of the arrow B and can 4 6 41 move the free arm of the switching rocker 26 in the opposite sense to that of the arrow P3.

The structure of the interior of the base member 1' can moreover largely correspond to the arrangement shown in Figs. 1,2 and 5 and therefore Is not shown in detail in the drawing.

Finally Fig. 4 illustrates an embodiment of switching device which can be driven by means of a push button 30 which directly influences a control slide - as usual 10 against a force provided by an energy store (springs), where the drive force in the direction of the arrow P4 is to be applied manually to the push button. Fig. 4 illustrates the control slide in the pressure relieved upper end position in which it is held by two compression springs 27’ by which it is directly influenced and which form the energy store.

Fig. 5 illustrates (from top to bottom) firstly a section of the control slide 7 with the struts 20 and 21 which are each shown broken off, where the strut 21 has a drive opening 22 with drive cheeks reinforced in the direction of movement of the slide and which are acted on by the drive journal 23. The drive journal itself has not been shown in Fig. 5 but is symbolised by the axis a of the journal and the drive direction, orientated at right angles thereto as indicated by the arrow A.

Two parallel control crossbars 8 extend at right angles between the struts. It can easily be imagined that when the two struts extend beyond the illustrated break-off points there is space for the further crossbars (not shown in Fig. 5) which belong to the complete control slide.

The opposite vertical side surfaces 11 of the crossbars 8 each extending in the region of the struts 20, 21, can be moved rectilinearly in slots 9 of a side wall of the base member 1 part of which has been shown in the lower part of Fig. 5.

Between those sections of the control crossbars which are used for guide purposes in the base member, and the strip 20 the side surfaces 11 are each provided with a deflection surface or land 12 projecting towards an adjacent contact spring 2 and an inclined abutting surface 13 which links the deflection surface or land 12 and the surface 11. Furthermore in the embodiment shown in Fig. 5 one section of each crossbar side surface directly behind the inclined abutting surface 13 recesses behind the level of the surface 11 in order to avoid contact between the drive cam of the relevant contact spring and the relevant region of the control crossbar when the control slide is in the appropriate actuating position.

Two of the deflectable contact springs 2 which are assigned to the two side surfaces 11 of one of the crossbars are shown in Fig. 5 below the associated crossbar 8 of the control slide 7. The ends of the contact springs which are to be firmly held in the base member have not been shown. Rather there can be seen the V-shaped cam portion 14 which projects towards the corresponding side surface of the control crossbar 8, and likewise the deflectable end portion 4 of the contact spring 2 with wire-like elements 31 which are arranged in the' contact zone and consist of appropriate contact material, and with a symmetrical longitudinal slot 32 which serves to separate two contact ends which may be deformed dependently-Of one another. The two contact springs are biased in the direction of the drive cam portions, thus towards each other.

Two rigid contact abutments 6 which are combined as fins of a U profile member are illustrated below the deflectable contact springs 2. The front edges 15 of the contact surfaces of the abutments 6 are free and separate in the region adjoining the base 34 of the profile member.

In this way they project beyond the base region and allow a firmly positioned insertion in slots 16 in a side wall of the base member.

The base 34 of the 0 profile is adjoined by a flat conductor strip 18 which is provided with angular lateral projections and which can be held between orientating elements 19 of the flat base surface in a functionally desirable fashion.

Axes b,d,e,f,2 and h and likewise chain-line details indicate the functional connection between control slide 7, deflectable contact springs 2, counter contact surfaces of the abutments 6, conductor strip 18 and base member 1.

Thus with the arrangements described above a number of independent individual contacts each consisting of a deflectable contact leaf spring and an assigned rigidly /1 4 6 4 1 held abutment contact can be mounted on the base member.

In each pair of contacts the resilient bias of the contact leaf springs can generate adequate force for ohmic contact with the rigidly held abutment contact.

Also, operating movement of the control slide beyond the contact-operating range does not result in an additional deflection of the contact leaf spring. Instead the cam of the spring in question slides, with slight friction, over the deflecting surface which projects parallel above the side surface of the crossbar so that the cam is held unchanged in its deflected state.

The deflected state of a contact leaf spring can now correspond for example to a sufficiently open.>contact position between the spring contact and the abutment contact.

On the other hand the contacts are closed with sufficient force when the drive tip of the cam is released by the deflection surface of the control slide and takes up a position free of contact with the side surface of th.e slide crossbar. In this case the resilient bias of the spring can be entirely converted into contact force.

None of the deflectable contact leaf springs need to be actuated beyond these two end positions even when the switching sequence is to be staggered since the deflection is determined not by the path of the control slide but by the difference in level.between the deflection surface and the base plane of the side surface of the slide crossbar in question. 5464 1 By contrast, in a switch designed in this way the staggering of the actuating sequence of the individual contacts can be effected without adjustment by providing an •initial, predetermined stagger in the arrangement of the deflection surfaces on the individual slide crossbars in their positions relative to the direction of movement of the control slide.

The crossbars of the control slide can be assigned to the deflectable contact leaf springs in such manner that a crossbar in each case acts upon a contact leaf spring.

However, the two opposite side surfaces of the crossbar can equally well act upon adjacent contact springs which are deflectable in opposing directions and for this purpose can be provided with deflection surfaces. The point of the cam can be· provided with·a clearly defined bending radius which. . facilitates low impact sliding of the cam even in the junction zone between the flat side wall of the crossbar and the inclined and deflection surfaces. Each cam can be formed by a peg made of insulating material and secured in an opening in the contact leaf spring in place of the elbow.

The control slide described above comprises a compact, stable component which can easily be produced as an integrally formed synthetic shaped part.

The symmetrical double fixed contact component can be considered as the basic unit for stamped/bending manufacture. For different fixed contact arrangements, by means of special dividing outs the basic unit can provide individual fixed contact components of different forms for different types of use in the switch in question. 16 11

Claims (9)

CLAIMS:

1. An electro-mechanical switch for telephone apparatus, comprising a base part made of insulating material and in which contact springs in the form of leaf springs are arranged one beside another in parallel spaced planes so as to cover one another as regards their outline, the contact springs being in each case firmly clamped in the base part at one end and at the other end can be elastically deflected at right angles to their plane of orientation by means of a control slide which is guided so as to be linearly movable on the base part, on the base part the guide path of the control slide being oriented parallel to the longitudinal direction of the contact springs and the control slide being provided with rigid, essentially parallel bars which engage between the contact springs, parallel to the contact springs from the deflectable ends thereof; on their side surfaces which face towards the deflectable contact springs, the control bars being in each case provided with both a sloped contact surface, which protrudes from the plane of the respective lateral surface, and also with a deflecting surface which adjoins the contact eurface and extends at a constant distance from the lateral starting plane; in the vicinity of their free ends, the deflectable contact springs being in each case provided with a driving cam which protrudes at right angles to the deflecting surface of the adjacent control bar, and having an elastic prestress which is oriented in the direction of the driving cam? and adjacent the free ends of the deflectable contact springs, in each case from the side 5 of the deflecting surface of the adjacent side surface of the control bar, a counter-contact being provided which has a parallel-extending, rigid contact surface and is fixed to the base part.

2. An electro-mechanical switch as claimed in Claim 1, 10 wherein the driving cams of the deflectable contact springs are in each case formed as a V-shaped shoulder which is oriented at right angles to the plane of the spring and at right angles to the length of the spring.

3. An electro-mechanical switch as claimed in Claim 1, 15 wherein at their two end zones, the parallel bars of the control slide are rigidly connected to one another by means of a beam-like cross-piece which is oriented at right angles to the length of the bars.

4. An electro-mechanical switch as claimed in Claim 3, 20 wherein bars and cross-beams of the control slide have a profile which is essentially rectangular.

5. An electro-mechanical switch as claimed in Claim 4, wherein one of the cross-beams of the control slide has 5464 1 at least one opening which is oriented at right angles to the length of the bars and cross-beams and serves to engage a driving pin of an actuating element which is pivotable on the base part. 5

6. An electro-mechanical switch as claimed in Claim 1, wherein the rigid contact surfaces which are provided as counter-contacts, are limited, as far as their length is concerned, to the length of the free end region of the deflectable contact springs behind the driving cam. 10

7. An electro-mechanical switch as claimed in Claim 6, wherein a flat conductor strip which is bent at right angles is attached to the contact surfaces, which are provided as counter-contacts, said conductor strip in the situation when it is placed on the bottom plane of 15 the base part is positioned parallel to the flat springs which constitute the deflectable contact springs, and so as to function properly by means of structural elements which protrude from the flat contact surface of the bottom plane, said conductor strip at its end facing 20 away from the contact surface changing into a connecting tag, by means of which it protrudes vertically from one of the outer boundary surfaces of the base part.

8. An electro-mechanical switch as claimed in Claim 7, wherein two contact surfaces which serve as counter54641 contacts, are in each case formed as parallel fins of a U-profile; and that the base of the profile which extends at right angles thereto, represents the output plane of a common conductor strip which changes into the 5 connecting tag.

9. An electro-mechanical switch for telephone apparatus, substantially as hereinbefore described with particular reference to and as illustrated in Figs, l, 2 and 5, Fig. 3 and Fig. 4 of the accompanying drawings. F. R. KELLY ϋ CO., AGENTS FOR THE APPLICANTS. SIEMENS AKTIENGESELLSCHAFT Sheet 1