EP1071106B1 - Switch with dual pressure - Google Patents

Abstract

The two function switch has an off position where the input track (8) and conductor zone are not connected. When the button (4) is pushed to a first position the input track and output track (9,10) are connected, and with a greater force push, output tracks of a second zone (15) are connected activating a second function.

Description

The invention relates to a pressure switch for controlling at least two functions in response to a pressure exerted on the switch, respectively.

Such a switch is used for different types of electrical equipment, such as, for example, photographic devices, camcorders or telephones. The purpose of this switch is to minimize the number of keys and increase the ergonomics of these devices.

With this type of switch, by a first pressing of low pressure, it operates a first function, such as for example a preparatory mode as a preselection. In addition, by a second press of greater pressure, a second function is activated, such as for example an operational mode as a validation of the preselection.

No. 5,313,027, which is considered to be the closest state of the art, discloses a switch of the aforementioned type comprising an insulating substrate having an outer annular contact zone and an inner annular contact zone. A deformable conductive cup, disposed opposite said zones, is adapted to be in contact with the outer zone firstly following a first bearing on the latter and secondly on the two zones following a second support of stronger pressure. The cup is covered with an insulating membrane which is fixed to the substrate by means of spacers in order to keep the cup away from the zones, in the rest position.

This switch has a number of disadvantages. Not only are additional pieces necessary to keep the cup off the substrate, but it is also difficult to control the space required between the cup and the substrate in such a situation. The edges of the cup must indeed extend in a plane parallel to the substrate so that the contact following the first support is complete.

Furthermore, the attachment of the cup to the membrane, which is complex, must be perfect for proper operation.

There are also switches comprising a pair of cups arranged one above the other so that by a first support, the outer cup pushes the inner cup in contact with the outer zone of the substrate and by a second support, the inner cup further comes in contact with the inner area.

Such a solution is difficult to implement and does not optimize the size of the switch, in particular because of the presence of two cups.

The invention therefore aims to overcome the disadvantages of the prior art by providing a high performance switch, simple to implement and minimum space requirement, this switch to allow ergonomic use to access different functions.

For this purpose, the invention proposes a switch of the aforementioned type, comprising an insulating substrate comprising at least a first and a second conductive area able to trigger respectively a first and a second function. At least the first conductive zone comprises at least two electrically insulated portions of the other, the first portion being connected to an input track and the second portion to an output track. The second conductive zone is further connected to at least one additional output track.

The switch further comprises a membrane comprising at least a first and a second contact areas able to contact respectively the first and second conductive areas depending on the pressure exerted on the membrane. The first contact zone comprises at least two regions electrically interconnected and able to contact the portions respectively, so as to connect the input and output tracks together.

• une position de repos, où elle est en contact partiel avec au moins la première zone conductrice, la piste d'entrée n'étant reliée à aucune piste de sortie, aucune fonction n'étant exécutée ;
• une première position de sollicitation, où un premier appui provoque la liaison entre la piste d'entrée et la piste de sortie de la première zone conductrice, cette première position de sollicitation étant destinée à déclencher l'exécution de la première fonction; et
• une deuxième position de sollicitation, où un deuxième appui, de force plus importante que le premier, provoque le contact de chaque zone de contact avec chaque zone conductrice, cette deuxième position de sollicitation étant destinée à déclencher l'exécution de la deuxième fonction.

The membrane can take at least three positions:

• a rest position, where it is in partial contact with at least the first conductive area, the input track being connected to no output track, no function being performed;
• a first biasing position, wherein a first pressing causes the connection between the input track and the output track of the first conductive zone, this first biasing position being intended to trigger the execution of the first function; and
• a second biasing position, where a second support, greater force than the first, causes the contact of each contact zone with each conductive zone, this second biasing position being intended to trigger the execution of the second function.

The invention also relates to electrical equipment comprising a pressure switch mentioned above, and means of execution of at least first and second functions, the execution of the functions being triggered in response respectively to a pressure exerted on the switch.

The function triggered in the first solicitation position is for example a preselection function, while the function triggered in the second solicitation position is for example a selection function.

In a particular embodiment, the insulating substrate comprises two conductive zones each forming a substantially circular ring, the first conductive zone being external to the second conductive zone.

According to a first embodiment, the first conductive zone comprises at least three portions, a first of which is connected to an input track and the second and third are connected by output tracks to programmed circuits so that the first function is triggered as soon as the three portions are contacted by the corresponding regions.

According to a second embodiment, the first conductive zone comprises at least three portions, of which a first is connected to an input track and the second and third are connected by output tracks to programmed circuits so that a first action is triggered when the first and second portions are contacted, while a second action is triggered when the first and third portions are contacted.

In this situation, the electrical equipment may comprise means for executing at least two actions allowing displacement in two different directions of a cursor, in response to the activation of the switch.

The switch can then be part of a navigation button.

At least a portion of the outer face of the membrane adheres to a flexible holding envelope, adjacent to the insulating substrate outside the conductive zones. This envelope keeps the membrane in the rest position while allowing its passage in first and second biasing positions.

The switch of the invention further comprises a key adapted to act on the outer face of the membrane to exert pressure.

• Les figures 1 et 2 représentent des vues schématiques en perspective du commutateur à pression de l'invention, la figure 1 montrant partiellement l'enveloppe souple de maintien.
• La figure 3 représente une vue de dessus du substrat isolant surmonté de la membrane.
• Les figures 4 et 5 sont des vues respectivement latérale et de dessus du commutateur à pression de l'invention, lorsqu'il est en position de repos.
• Les figures 6 et 7 sont des vues en coupe selon respectivement les lignes VI-VI et VII-VII de la figure 5.
• Les figures 8 et 9 représentent des vues en coupe analogues à la vue de la figure 6, montrant respectivement la première et la deuxième positions de sollicitation du commutateur à pression de l'invention.
• Enfin, la figure 10 est une vue schématique de dessous montrant la membrane et ses zones de contact.

The invention will be better understood in light of the detailed description which follows with reference to the accompanying drawings.

• Figures 1 and 2 show schematic perspective views of the pressure switch of the invention, Figure 1 partially showing the flexible holding envelope.
• FIG. 3 represents a view from above of the insulating substrate surmounted by the membrane.
• Figures 4 and 5 are respectively side and top views of the pressure switch of the invention, when in the rest position.
• Figures 6 and 7 are sectional views respectively along the lines VI-VI and VII-VII of Figure 5.
• Figures 8 and 9 show sectional views similar to the view of Figure 6, showing respectively the first and second biasing positions of the pressure switch of the invention.
• Finally, Figure 10 is a schematic bottom view showing the membrane and its contact areas.

With reference in particular to FIGS. 1 and 2, the switch 1 comprises an insulating substrate 2 comprising tracks and electrical circuits and surmounted by a membrane 3 adapted to make contact with these electrical circuits.

To establish these contacts, the membrane 3 is moved and deformed under the effect of pressures exerted on its outer face 3a by a key 4.

Each of the elements forming the switch 1 of the invention is now described in detail.

As shown in Figures 1 to 3, the insulating substrate 2 is formed of a plate having a first and a second conductive regions 6, 7 each forming a substantially circular ring. The first conductive zone 6 is external to the second conductive zone 7.

The first conductive zone 6 comprises four portions A, B, C, D, which are electrically isolated and electrically isolated from one another.

Each of these portions A, B, C, D has the general shape of a disc. Of course, other forms can be envisaged.

The portions A to D are distributed circumferentially along the ring forming said first conductive zone 6, with, in the present embodiment, a constant distance, of the order of 90 ° between them.

The first portion A is connected to an input track 8, adapted to bring electric current.

The second and third portions B, C, which are arranged on either side of the first portion A, are each connected by an output track 9, 10 to a particular electrical circuit 11, 12.

Finally, the fourth portion D, which is arranged opposite the first portion A, is electrically inactive. It is indeed connected to no circuit.

Thus, the first and fourth portions A, D are aligned along a plane substantially perpendicular to the plane along which the second and third portions B, C are aligned (see FIGS. 3 and 5).

The electrical circuits 11 and 12 are programmed so that when a contact is established simultaneously with each of the portions A to D, a first function is performed.

This function is for example a preselection in a menu that can be displayed on a screen (not shown) connected to the switch 1.

In an alternative embodiment, the electrical circuit 11 can be programmed so that a first action is performed when the contact is established simultaneously with the portions A, B, D. In addition, the electrical circuit 12 can be programmed so that a second action is performed when the contact is established simultaneously with the portions A, C, D.

In this situation, it can be expected that these actions are part of a preselection function and allow the movement in two different directions (for example up, down) of a cursor, the latter can for example move in a menu displayed on a screen. The switch 1 can then be integrated in a navigation button.

It is understood that other functions or actions may be provided.

Alternatively, one can consider deleting the portion D or to add other portions able to trigger other functions or actions.

The second conducting zone 7 comprises a single portion E of shape and dimension similar to those of the portions A to D.

In the embodiment shown, the portion E is disposed at the center of the ring having the portions A to D. It is therefore equidistant from each of them.

The portion E is connected by an output track 13 to an electric circuit 14, programmed so that when a contact is established simultaneously with each of the portions A to E, a second function is performed.

This second function is for example a validation function of a preselected choice at the end of the first function or action.

In alternative embodiments, it can be envisaged that the second function is executed as soon as the simultaneous contact with the portions A, B, D, E or A, C, D, E is established, as long as the portion D exists. In any case, the second function can be executed only if the portion A, which is connected to a current input track, and the portion E are contacted simultaneously.

It can also be provided that the second conductive zone 7 comprises several portions in the same manner as the first conductive zone 6 to allow the execution of other functions.

The membrane 3 has the shape of a cup of substantially circular general section. More precisely, it has a hemispherical general shape.

It is made of a deformable material so as to make the switch hyperstatic. It is for example made of flexible metal by stamping and cutting.

The membrane 3 has on its inner face 3b, which is intended to come opposite the insulating substrate 2, a first and a second contact areas 15, 16.

As will be seen below, these contact zones 15, 16 are able to contact respectively the first and the second conductive zones 6, 7 as a function of the pressure exerted on the membrane 3.

The first contact zone 15 comprises four regions A ', B', C ', D' interconnected electrically and capable of respectively contacting the portions A, B, C, D, so as to connect the input tracks to each other. 8 and output 9, 10.

As represented in particular in FIG. 10, the portions A 'to D' are part of a tab 15a to 15d projecting from the free edge 17 of the membrane 3.

More specifically, the membrane 3 is formed of a hemispherical dome 18 extended from its free edge 17 by four tabs 15a to 15d.

In the embodiment shown, the gap separating two adjacent tabs is constant and of the order of 90 °.

Each of the legs 15a to 15d follows the general curvature of the dome 18.

They have at their free end a flat surface forming a contact region A 'to D'. These surfaces extend in planes substantially parallel to each other and to the outside of the dome 18.

More precisely, the regions A 'and D' extend in the same first plane, while the regions B 'and C' extend in the same second plane, substantially parallel to the first plane, the second plane being closer to the top of the dome 18.

In the embodiment shown, the gap between the two planes is of the order of 0.2 millimeters.

Plan view (Figure 10), the membrane 3 has substantially a star shape with four branches.

When the membrane 3 is placed, without effort or pressure, on the insulating substrate 2 with its concavity facing the conductive areas 6, 7, the free edge 17 is spaced apart from the insulating substrate 2.

Furthermore, in this position, only the tabs 15a and 15d, opposite to each other, rest on their plane surface on the insulating substrate 2, the other tabs 15c and 15d being spaced apart. More precisely, the membrane 3 is arranged so that the region A 'rests on the portion A and the region D' rests on the portion D.

This position of the membrane 3 corresponds to the rest position (see FIGS. 5 to 7).

So that the tabs 15b and 15c are in contact with the insulating substrate 2, and therefore with respectively the portions B, C, it will be necessary to exert a slight pressure on the membrane 3 from this rest position. The membrane 3 will then be in its first biasing position (see FIG. 8).

Preferably, the difference between the planes comprising the regions A ', D' on the one hand and the regions B ', C' on the other hand is minimum so that the displacement of the membrane 3 to pass from the position of rest in the first bias position is reduced.

The second contact zone 16 comprises a single contact region E 'adapted to be in contact with the portion E.

The region E 'extends at least at the top of the dome 18. It may further extend over the entire inner face of the dome 18.

This region E 'can be in contact with the corresponding portion E only when the membrane 3 is deformed so that its concavity is reversed under the effect of a sufficiently high pressure. The membrane 3 is then in its second biasing position (see Figure 9).

In the present embodiment, the membrane 3 is made in one piece in a conductive material. It is for example electrically conductive metal.

It could be envisaged that only its inner face 3b, or only the regions A 'to E', comprise a conductive material, for example by being covered.

The membrane 3 is held in the rest position by means of a flexible holding envelope 19, such as a thin film.

The material of the holding envelope 19 must be sufficiently thin and flexible to prevent any deformation of the membrane 3. It must indeed allow at least the transition from the rest position to the first and second biasing positions.

The holding envelope 19 is for example made of flexible plastic material or paper.

This holding envelope 19 is fixed rigidly, for example by gluing, to at least a portion of the outer face 3a (for example the outer face of the dome 18), or even to its entire surface. It thus substantially matches the outer shape of the membrane 3.

The holding envelope 19 is also fixed rigidly to the insulating substrate 2 outside the conductive zones 6, 7 (see FIGS. 1 and 5 to 8).

As indicated above, the membrane 3 is urged by means of a key 4 adapted to be in contact with the holding envelope 19.

In the embodiment shown, the key 4 is formed of two superimposed solid cylinders 4a, 4b by their base. One of the cylinders 4a has a larger diameter than the other.

The small cylinder 4b is intended to be in contact, by its base opposite the cylinder 4a, with the holding envelope 19 at least at the top of the dome 18. In addition, the other cylinder 4a is intended to receive the finger of the user.

The key 4 thus has a cross section T-shaped.

It is for example made in one piece.

Of course, other forms of touch can be considered. For example, in the embodiment allowing the execution of two directional actions for the outer conductive zone 6, it could be provided that the surface adapted to receive the finger of the user is curved with its concavity facing outwards so as to facilitate support to zones A, B, D or A, C, D.

Where appropriate, the movement of the key 4 is guided and limited by a wall extending substantially parallel to the insulating substrate 2 and surrounding said key.

We now describe each of the positions of the switch 1 which has just been described.

In the rest position, the key 4 exerts no pressure on the membrane 3. It is preferably discarded.

As shown in FIGS. 5 to 7, only the tabs 15a and 15d are in contact with the first conductive zone 6. There is then partial contact with this conductive zone 6. In addition, the tabs 15b and 15c are separated from the insulating substrate 2.

It is understood that in this embodiment, the symmetrical arrangement of each pair of legs 15a-15d and 15b-15c allows a certain balance and stability of the membrane 3 in the rest position.

In the first biasing position, a slight pressure exerted by the key 4 on the membrane 3, or more precisely on the holding envelope 19, causes the tabs 15b and 15c to come into contact with the conductive zone 6, namely the portions B and C.

There is then complete contact with this conductive zone 6. The connection between the input track 8 and the output tracks 9 and 10 is thus established and the first function can be performed.

It should be noted that in this position, the dome 18 is not deformed. Only a support at the top of the dome 18 makes it possible to lower the tabs 15b and 15c towards the insulating substrate 2.

In addition, it would be possible to provide means for blocking the key 4 in this first biasing position, these locking means nevertheless having to allow the passage towards the second biasing position.

The symmetry of the tabs 15b and 15c makes it possible to guarantee simultaneous contact of the two tabs 15b, 15c when effective support has been exerted on the membrane 3.

In addition, a security effect is guaranteed. Indeed, if the membrane is poorly fixed (for example, the plane comprising the regions B ', C' is not exactly parallel to the insulating substrate 2) so that in the rest position, only one of the legs 15b, 15c is in contact with the insulating substrate 2, the first function can be performed only after the support on the membrane 3 and not inadvertently.

In the second biasing position, a greater pressure than the one exerted by the key 4 on the membrane 3, causes the deformation of the dome 18. The concavity of the dome 18 is then reversed and the inner face of its top comes into contact with the portion E of the second conducting zone 7 (FIG. 9).

It should be noted that the holding envelope 19 also follows this deformation.

In this situation, the contact with the first conducting zone 6 is complete.

When the key 4 is released, the dome 18 automatically returns to its rest position and the tabs 15b and 15c are spaced apart from the insulating substrate 2. The membrane 3 then returns to its rest position.

Of course, the invention is not limited to the embodiments that have just been described.

One could indeed provide a different number or another arrangement of portions A to D of the first conductive zone 6, with a different gap, and therefore legs 15a to 15d.

Claims (16)

1. Push button switch intended to control at least two functions in response to a respective pressing force placed on the switch, comprising:

   - in insulating substrate (2) comprising at least a first and a second conductive zone (6,7) able to trigger a first and second function respectively, at least the first conductive zone (6) comprising at least two portions (A,B,C,D) electrically insulated from one another, the first portion (A) being connected to an input track (8) and the second portion (B,C) to an output track (9,10), the second conductive zone (7) also being connected to at least one additional output track (13);

   - a membrane (3) comprising at least a first and a second contact zone (15,16) able to contact the first and second conductive zones (6,7) respectively in relation to the pressing force placed on the membrane; the first contact zone (15) comprising at least two regions (A',B',C',D') electrically connected together and able to contact portions (A,B,C,D) respectively so as to connect together the input and output tracks;

   characterized in that the membrane can take up at least three positions:

   - a rest position in which it is in partial contact with at least the first conductive zone (6), the input track (8) not being connected to any output track, no function being executed;

   - a first demand position, in which a first pressing force causes the connection between the input track (8) and the output track (9,10) of the first conductive zone (6), this first demand position being intended to trigger execution of the first function; and

   - a second demand position, in which a second pressing force, greater than the first, causes contact between each contact zone (15,16) with each conductive zone (6,7) this second demand position being intended to trigger execution of the second function.
2. Push button switch as in claim 1, characterized in that the membrane (3) is a deformable dome arranged so that its concavity faces the conductive zones (6,7).
3. Push button switch as in claim 1 or 2, characterized in that the membrane (3) is generally of substantially circular section.
4. Push button switch as in any of claims 1 to 3, characterized in that each region (A',B',C',D') is part of a tab (15a, 15b, 15c, 15d) projecting from the free edge (17) of membrane (3).
5. Push button switch as in any of claims 1 to 4, characterized in that the inner surface (3b) of the membrane, which faces the conductive zones (6,7), comprises a conductive material.
6. Push button switch as in any of claims 1 to 5, characterized in that the insulating substrate (2) comprises two conductive zones (6,7) each contained in a substantially circular ring, the first conductive zone (6) lying outside the second conductive zone (7).
7. Push button switch as in any of claims 1 to 6, characterized in that the second conductive zone (7) comprises a single portion (E).
8. Push button switch as in any of claims 1 to 7, characterized in that the first conductive zone (6) comprises at least three portions (A,B,C) of which a first portion (A) is connected to an input track (8) and the second and third (B,C) are connected via output tracks (9,10) to circuits (11,12) programmed so that the first function is able to be triggered as soon as the three portions (A,B,C) are contacted by the corresponding regions (A',B',C').
9. Push button switch as in any of claims 1 to 7, characterized in that the first conductive zone (6) comprises at least three portions (A,B,C) of which a first (A) is connected to an input track and the second and third (B,C) are connected via output tracks to circuits programmed so that a first action can be triggered when the first and second portions (A,B) are contacted, whilst a second action can be triggered when the first and third portions (A,C) are contacted.
10. Push button switch as in any of claims 7 to 9, characterized in that the second and third portions (B,C) are arranged either side of the first (A).
11. Push button switch as in any of claims 1 to 10, characterized in that it comprises a flexible supporting envelope (19) to which adheres at least part of the outer surface (3a) of membrane (3), and adjoining the insulating substrate (2) outside the conductive zones (6,7), the envelope holding the membrane in rest position whilst allowing it to be switched to the first and second demand positions.
12. Push button switch as in any of claims 1 to 11, characterized in that it also comprises a button (4) able to act on the outer surface (3a) of the membrane to place a pressing force thereupon.
13. Navigational button characterized in that it comprises a push button switch as in claim 9 or as in any of claims 10 to 12, when they depend on claim 9.
14. Electrical equipment containing a push button switch as in any of claims 1 to 13, and means for executing at least a first and a second function, the execution of the functions being triggered in response to a respective pressing force applied to the switch.
15. Electrical equipment as in claim 14, characterized in that the function triggered in first demand position is a pre-selection function, whilst the function triggered in second demand position is a selection function.
16. Electrical equipment as in claim 14 or 15, characterized in that it comprises means for executing at least two actions enabling the displacement of a cursor in two different directions in response to actuation of the switch.

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