SWITCH CONTROL ELEMENT FOR SWITCH AND PUSHBUTTON WITH SUCH A SWITCH CONTROL ELEMENT

Abstract

A switch control element comprising:• at least one silicone dome (7);• at least one actuating means (5) acting on the at least one silicone dome (7) for closing and selectively opening electrical contacts of at least one switch (6);wherein• the at least one actuating means (5) is moved along a vertical axis (Z) by a force exerted by a pushing means (3);• between the pushing means (3) and the at least one actuating means (5) there is at least one elastic means (4) adapted to be compressed by the pushing means (3) while the at least one silicone dome (7) is compressed, accumulating energy, and to expand, releasing the stored energy, while the at least one silicone dome (7) collapses towards the switch (6);• the switch control element extends substantially vertically along the vertical axis (Z);characterized in that the at least one elastic means (4) is made of silicone;

Description

[0001] The invention relates to a switch control element with silicone domes.

[0002] The main types of switch systems currently used in the automotive sector can be summarized as follows: - Switches with quick-action metal foils; - Switch with silicone bubbles and integrated contact; - Switches with silicone bubbles and metal contact, forming a whole with the electronic circuit; - Switches with snap-on metal domes that can be actuated either directly or via a silicone intermediate link; - external switch operated by means of an actuator and silicone domes.

[0003] These different types of operating principles have certain inherent mechanical properties, such as forces, strokes and noise, and electrical properties, so in some cases they may not meet the new requirements of the automotive world.

[0004] In particular, the use of external monolithic switches for opening and closing circuits introduces an indeterminate variable into the determination of the contact or switching point of the switch itself.

[0005] Furthermore, external switches have inherent mechanical properties that must be duly considered to achieve the tactile characteristics required in the automotive sector.

[0006] DE 84 00 256 U1 discloses a push button comprising a button element, a contact element acted upon by the button element, and an elastic element exerting a force on the button element opposite to the actuation direction. A second elastic element, which holds the contact element to be actuated in its rest position, has a lower spring stiffness than the first elastic element arranged between the button element and the contact element to be actuated. Thus, when the button element is actuated, an overtravel occurs after the contact element has already made contact, thereby increasing the contact duration for the purpose of reliably exceeding a minimum actuation duration of the contact.

[0007] US 4,931,606 A discloses a key switch mechanism on a membrane switch. In this mechanism, a spring supported off-center on the key extends between the key and the switchable part of the membrane switch. When the key is actuated, the spring initially accommodates an initial movement of the key under linear compression before abruptly buckling as the compression increases due to its off-center support. This deformation of the spring actuates the membrane switch.

[0008] For the purposes of the present invention, the term "external switch" refers to a monolithic solid-state switch comprising an outer housing and a pushbutton electrically connected to a printed circuit board. The switch control element acts on the external switch.

[0009] For the purposes of the present invention, the term "feel" refers to the force and displacement perceived by the user while operating a key of a pushbutton that includes a switch.

[0010] Switch control elements, such as the one described in IT TO20100636 A by Bitron, are known in which, for closing a switch comprising, for example, conductive elements or silicone domes, the switch control element comprises a metal foil adapted to create an elastic lever and to modify the force / displacement response of the element with respect to the intrinsic property of a silicone dome for the purpose of accelerating the response of the switch and ensuring the appropriate switching of the switch.

[0011] The solution described in the aforementioned patent application is difficult to implement for operating an external switch.

[0012] The present invention aims to solve the aforementioned problems by providing a switch control element that can adapt to any type of switch implemented and therefore ensures the desired feeling in response to an operation.

[0013] The switch control element described below was designed to create a family of switches featuring a switch actuation and closing system that makes it possible to achieve force / deflection characteristics that meet the new requirements of the market, while at the same time optimizing the electrical performance.

[0014] The new element also aims to exploit some of the elastic properties of silicone to achieve new results in terms of feel and sound, without increasing the number of components or degrading the electrical aspects of the switch.

[0015] One aspect of the present invention relates to a switch control element having the features recited in the appended independent claim 1.

[0016] Additional features are set out in the appended dependent claims.

[0017] The features and advantages of the element according to the invention will become apparent from the following description of different embodiments thereof and from the attached drawings: • The Fig. 1A, Fig. 1B and Fig. 1C shows a cross-section of a push button comprising the switch control element according to the invention in different operating configurations; in particular, Fig. 1A the switch control element in idle state, Fig. 1B shows the switch control element in the load state, Fig. 1C shows the switch control element in the switching mode; • Fig. 2 is an exploded view of the push button of the Fig. 1A to 1C; • Fig. 3 shows a portion of the push button incorporating the switch control element according to the invention; • Fig. 4 shows the force / deflection graph of the switch control element according to the invention compared with the force / deflection graph of a prior art switch control element; • The Fig. 5A and Fig. 5B show two different embodiments of the switch controlled by the switch control element according to the invention.

[0018] With reference to the above drawings, the switch control element comprises: at least one silicone dome 7 and at least one actuating means 5 acting on the at least one silicone dome 7.

[0019] The at least one actuating means 5 is adapted to selectively close and open electrical contacts of at least one switch 6.

[0020] The at least one actuating means 5 is moved by a force exerted by a pressing means 3. The force exerted by the one pressing means 3 is preferably parallel to a vertical axis "Z" and more preferably coincident with the vertical axis of the push button equipped with the switch control element according to the invention.

[0021] Between the one pressing means 3 and the at least one actuating means 5 there is at least one elastic means 4 which is adapted to be compressed by the pressing element 3 while the at least one silicone dome 7 is compressed and to expand while the at least one dome 7 collapses towards the switch 6.

[0022] Preferably, the switch control element according to the invention extends substantially vertically along the "zZ" axis, and in particular, the actuating means 5 is located on top of the silicone dome 7. The pressing means 3 is in turn arranged on top of the actuating means 5. As mentioned above, the elastic means 4 is present between the actuating means 5 and the pressing means 3.

[0023] In the preferred embodiment, the switch control element according to the invention is applicable to a push button comprising a button 1 adapted to be pressed by the user and a support structure 11 defining a cavity 110 in which the switch control element of the present invention is arranged as shown in the attached drawings.

[0024] In the non-limiting solution illustrated here, the button 1 comprises a central element 1a on which a cover 1b is located, for example, indicating the function of the push button. The button 1 is surrounded by an external cover element 2 adapted to cover the connection point of the push button in the vehicle or boat. The external cover element 2 is confined to the support structure 11, for example, by a positioning element or bayonet fastener.

[0025] The button 1 forms a whole with the pressing means 3 and therefore transmits the force exerted on the button 1 to the pressing means 3 for the purpose of moving the actuating means 5 and switching the switch 6.

[0026] The pusher means 3 is attached to the key 1, preferably to the central element 1a, by a positioning element or bayonet fastening means. In the preferred embodiment, the pusher means 3 comprises at least one fastening portion 32 adapted to be inserted into at least one recess formed in the central element 1a of the key 1.

[0027] In the preferred embodiment, the at least one elastic means 4 is made of silicone, preferably with elastic properties similar to a silicone mat 71 which surrounds the silicone dome 7.

[0028] The at least one elastic means 4 has a circular shape, preferably an annular shape, such as with a parallelogram section.

[0029] In alternative embodiments not shown, the elastic means 4 is at least a spiral spring.

[0030] In the non-limiting embodiment illustrated here, both the push means 3 and the actuating means 5 have a substantially cylindrical shape. In the preferred embodiment, the elements enclosed in the push button, such as the button 1 and the support structure 11, also have a cylindrical structure.

[0031] In the preferred embodiment, the elastic means 4 is a ring having a rectangular cross-section.

[0032] Preferably, the at least one elastic means 4 is positioned in a housing 51 enclosed in the actuating means 5.

[0033] Preferably, the housing 51 has a section substantially similar to the section of the elastic means 4 to prevent any movement of the elastic means 4 in undesired directions. In particular, the shape of the housing 51 is such that the elastic element 4 cannot move along directions that are not parallel to a vertical axis "Z" and such that it can expand while the same elastic means 4 is compressed.

[0034] The pressing means 3 comprises a plunger portion 33 for pressing against the elastic means 4 when the switch control element according to the invention is assembled.

[0035] As shown in Fig. 2, the elastic means 4, which is interposed between the actuating means 5 and the pressing means 3, is shaped like a ring having a rectangular cross-section.

[0036] In a rest-state configuration of the switch control element of the present invention, the elastic means 4 maintains the pusher means 3 and the actuating means 4 at a distance from each other. In the rest-state configuration, the elastic means 4 acts as a spacer element between the pusher means 3 and the actuating means 5.

[0037] The pressing means 3 comprises first guides 31. The first guides 31 are adapted to slide along rails 111 enclosed in the internal cavity 110 defined by the support structure 11.

[0038] The actuating means 5 comprises second guides 50 adapted to slide along rails 111 enclosed in the cavity 110.

[0039] In the preferred embodiment, the cavity 110 has a circular cross-section and comprises four equally spaced rails 111.

[0040] Due to the presence of the first and second guides (31, 50), which are slidable along the rails 111, only the vertical component of an applied force can move the pusher 3 and therefore causes the actuating means 5 to act on the switch 6. To ensure the correct positioning of the pusher 3 relative to the actuating means 5, the actuating means 5 comprises a centering means 521 adapted to interact with the pusher 3. In the preferred embodiment, the centering means 521 is enclosed in a cavity 52 formed in the central portion of the actuating means 5.

[0041] More precisely, the cavity 52 is a conical hole whose largest diameter is smaller than the diameter of the housing 51.

[0042] In the preferred embodiment, switch 6 is external and is a separate, monolithic, contactless electrical element. The switch includes an outer housing 61 and a pushbutton 62. Switch 6 is preferably a switch having dual independent contacts.

[0043] The switch 6 is electrically connected by soldering to a circuit board 8. The same circuit board 8 is electrically connected to a connector 10 via suitable pins 9. The connector 10 is adapted to connect the push button to the electrical circuit of the vehicle or boat in which the push button is installed. The connector 10 is attached to the lower end of the support structure 11, opposite the end where the button 1 is located.

[0044] A silicone mat 70 is positioned on the circuit board 8, which comprises at least one silicone dome 7.

[0045] In alternative embodiments described in the Fig. 5A and Fig. 5B, the switch 6 is integrated into the switch control element according to the invention; in particular, it is enclosed in a silicone dome 7. In such embodiments, the silicone dome in turn comprises at least one conductive portion 66 for closing an electrical circuit enclosed in the circuit board 8 when the same silicone dome 7 collapses onto the circuit board 8.

[0046] In different embodiments (not shown), the conductive portion 66 is a metal foil which is bonded to the silicone dome 7 as shown in Fig. 5A, or which may be connected between the silicone dome 7 and the circuit board 8 as shown in Fig. 5B is interposed.

[0047] The switch control can have three operating configurations: • a rest state configuration, whereby no forces are applied to the pressing means 3, for example by the button 1 as shown in Fig. 1A; • a switching operation configuration, wherein following the application of a force to the pressing means 3, the actuating means 5 causes the contacts of the switch 6 to switch from open to closed or vice versa, as exemplified in Fig. 1C, and • a load operating configuration controlled by the switch control element during the transition from the sleep mode configuration to the switch operating configuration as shown in Fig. 1B is taken.

[0048] In the resting state configuration, all the means included in the switch control element of the present invention are in an extended configuration; in particular, the silicone dome 7 is raised and the elastic means 4 is extended. The extension of the elastic means 4 causes a gap between the actuating means 5 and the pressing means 3, so that the two means (5, 3) are in Fig. 1A should be kept at a distance.

[0049] The gravitational forces exerted on the silicone dome 7 by the means (3, 5) are such that they do not cause the silicone dome 7 to collapse. Therefore, the idle state configuration does not allow inadvertent switching of the contacts of the switch 6.

[0050] The switch control element according to the invention remains in the rest state configuration until a force is exerted or applied to the pressing means 3, in particular until a force is exerted on the button 1 of the push button comprising the switch control element of the present invention.

[0051] Fig. Figure 4 shows the force / deflection curve of the switch control element according to the invention in comparison with the curve of switch control elements of the prior art using a simple silicone dome.

[0052] The application of a force to the pressing means 3 causes the switch control element to change into the load operating configuration before reaching the switching operating configuration.

[0053] In this latter loading operating configuration, the force exerted on the pusher 3 is not directly transferred to the actuating means 5 to compress the silicone dome 7; instead, the energy is stored by the elastic means 4, which is therefore compressed. This behavior translates into an initial linear portion of the force / displacement graph, with the curve showing a reduced slope compared to prior art switch control elements.

[0054] The compression of the elastic means 4 continues until a predetermined applied force value is reached. Furthermore, the applied force value corresponds to a deflection of the switch control element at which the gap between the pressing means 3 and the actuating means 5, created by the elastic means 4, is substantially zero, since the elastic means 4 is compressed and therefore reduces the gap between the two means (5, 3), as shown by way of example in Fig. 1B.

[0055] In the preferred embodiment of the switch control element according to the invention, the force applied is transmitted directly to the actuating means 5, which is in contact therewith as the force continues to be applied to the pressing means 3. The force applied directly to the actuating means 5 is in turn transmitted to the silicone dome 7, which collapses when a predetermined level of force applied to the silicone dome 7 is reached, thereby transitioning the switch control element of the present invention to the switching operation configuration.

[0056] In an alternative embodiment, the pressing means 3 remains at a distance from the actuating means 5, although it still allows the force to be transmitted through the elastic means 4 to the actuating means 5 to compress the silicone dome 7 until it collapses.

[0057] This behavior translates into the graphical representation of the force / displacement, which is shown in Fig. 4, into a larger deflection of the switch control element, whereby the applied force is the same and thus the feel of the switch control element is improved.

[0058] After the collapse of the at least one silicone dome 7, the elastic means 4 can expand towards the switch 6, thereby releasing the energy stored during the load operating configuration.

[0059] The expansion of the elastic means 4 caused by the collapse of the silicone dome 7 releases the accumulated energy towards the actuating means 5, thereby increasing the speed with which it causes the silicone dome 7 to collapse and the speed with which it acts on the switch 6.

[0060] This behavior translates into a delayed snap point or point of collapse of the silicone dome 7 in the force / displacement graph and, most importantly, a very rapid transition from maximum to minimum response of the silicone dome 7 itself.

[0061] The energy released by the expansion of the elastic means 4 causes the actuating means 5 to be subjected to such an acceleration that it quickly transitions into the switching operating configuration, whereby the silicone dome 7 itself has completely collapsed without further movement of the pressing element 3. In this operating configuration, the actuating means 5 has reached the end of its stroke and therefore switches the switch 6 as shown by way of example in Fig. 1C. When the silicone dome 7 comes into contact with the circuit 8, the stroke of the switch control element according to the invention is stopped, which corresponds to the switching of the switch 6.

[0062] The subsequent additional stroke of the pressing means 3 is again absorbed by the elastic means 4 without damage to the switch 6 or the switch control element of the present invention.

[0063] The acceleration during the transition from the load operating configuration to the switching operating configuration ensures correct switching of the switch 6, even if the mechanical properties of the switch 6 may cause a lot of dispersion of the contact point of the switch.

[0064] When no more force is exerted on the pressing means 3, the switch control element according to the invention returns to the rest state configuration thanks to the elastic energy of the silicone dome 7. The return curve, which in Fig. 4 shows essentially linear sections.

[0065] Any excess energy generated by the return of the silicone dome 7 is absorbed by the elastic means 4, which therefore makes the final portion of the force / displacement curve linear and avoids any resonance phenomena in the switch control element itself, since the residual energy is rapidly diminished.

[0066] In the preferred embodiment shown in the Fig. As shown in Figures 1A to 1C, 2, and 3, the actuating means 5 comprises at least one first contact portion 53 adapted to act on the at least one switch 6, and at least one plunger portion 54 adapted to press against two silicone domes 7. The two silicone domes 7 are arranged such that the movement of the actuating means 5 is compensated during the transition between the load operating configuration and the switching operating configuration.

[0067] The switch control element makes it possible to eliminate any uncertainty regarding the switching instant of the switch 6, even if the same switch 6 has a high inherent switching instant or contact point uncertainty. REFERENCE SYMBOL 1 button 1a Central element 1b Cover 1c recess 11 Support structure 110 cavity 111 rails 2 External cover element 3 Pressure medium 31 First tours 32 fastening section 33 Tappet section 4 Elastic agent 5 Actuating means 50 Second Tours 51 housings 52 cavity 521 Centering device 53 Contact section 54 Tappet section 6 switches 61 Outer casing 62 push button 66 Leading Section 7 silicone dome 71 Silicone mat 8 circuit board 9 pins 10 Connection “Z” Vertical axis

Claims

[1] Switch control element, comprising: • at least one silicone dome (7); • at least one actuating means (5) acting on the at least one silicone dome (7) for closing and selectively opening electrical contacts of at least one switch (6); where • the at least one actuating means (5) is moved along a vertical axis (Z) by a force exerted by a pressing means (3); • between the pressing means (3) and the at least one actuating means (5) there is at least one elastic means (4) which is adapted to be compressed by the pressing means (3) while the at least one silicone dome (7) is compressed, accumulating energy, and to expand, releasing the stored energy, while the at least one silicone dome (7) collapses towards the switch (6); • the switching control element extends substantially vertically along the vertical axis (Z); characterized by , that the at least one elastic means (4) is made of silicone. [2] Switch control element according to claim 1, wherein the at least one elastic means (4) is at least one spiral spring. [3] Switch control element according to claim 1, characterized by that the at least one elastic means (4) has a circular shape. [4] Switch control element according to claim 1 or claim 3, wherein the at least one elastic means (4) is positioned in a housing (51) of the actuating means (5). [5] A switch control element according to claim 4, wherein the housing (51) has a portion substantially similar to the portion of the elastic means (4). [6] Switch control element according to claim 1, wherein: - the pushing means (3) comprises first guides (31) for sliding along rails (111); - the actuating means (5) comprises second guides (50) for sliding along rails (111). [7] Switch control element according to claim 1, characterized by that the switch (6) is a separate electrical element comprising an outer housing (61) and a push button (62). [8] Switch control element according to claim 7, wherein the actuating means (5) comprises at least one first contact portion (53) for acting on the at least one switch (6) and at least one plunger portion (54) for pressing against the at least one silicone dome (7). [9] A switch control element according to claim 1, wherein the action of extending the elastic means (4) towards the switch (6) while the at least one silicone dome (7) collapses releases stored energy towards the actuating means (5), thereby increasing the speed of its action on the switch (6). [10] Switch control element according to claim 1, characterized by that the switch (6) is integrated into the switching control element by being enclosed in the silicone dome (7) or one of the silicone domes (7). [11] Push button for electronic circuits, characterized by that it comprises a switch control element according to claim 1.

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