IT202000031484A1 - INNOVATIVE CAPACITIVE KEY. - Google Patents

Description

TITLE: INNOVATIVE CAPACITIVE BUTTON.

The present invention refers to an innovative capacitive key, in particular a backlit key, which can be included in a simple to implement capacitive control keyboard.

In particular, the present invention relates to a capacitive key, in particular a backlit key, comprising a contact surface on the inner face of which ? applied an electrode which ? applied by pad printing.

Capacitive keys of different sizes and/or shapes are known which provide: a contact surface, on which the user impresses a force in order to activate/deactivate one or more keys? functions; an electrode located below said contact surface. This assembly rests on a support structure housed in the external structure of the control keyboard. This electrode? usually a metallic foil. Below said support structure ? there is a printed circuit board. This electrode? electrically connected to said printed circuit by means of a connection cable and/or a helical spring suitable for imparting an elastic thrust force on said electrode.

Normally, said electrode ? fixed in a hyper-rigid way to said contact surface, for example by means of connection, for example glues, or by interlocking or by being incorporated into the structure of the contact surface itself. These solutions are implemented to ensure that the antenna remains the most? as close as possible to the contact surface, avoiding the possibility of generating areas of the electrode at different distances from the contact surface.

These solutions are complex to implement, in particular it is difficult and complex to associate an electrode of metallic material with the internal surface of the key. Furthermore, in addition to increasing the costs of the single device, these solutions require more? complex button assembly process in order to correctly position the various components in order to guarantee the correct electrical connection between the electrode and the printed circuit.

The present invention proposes to solve these and other technical problems by realizing an innovative solution to guarantee the positioning of the electrode close to the contact surface, keeping the relative position unchanged, simplifying the assembly of the control keyboard and reducing production costs .

One aspect of the present invention relates to a capacitive key with the characteristics of the attached claim 1.

A further aspect of the present invention relates to a command keyboard of the capacitive type with the technical characteristics of the attached claim 10.

The characteristics and advantages of the key and of the control keyboard, according to the present invention, will be clear and evident from the following description of different possible embodiments and from the attached figures which illustrate respectively:

figure 1 shows the control keyboard comprising at least one capacitive key, according to the present invention, in a perspective view;

- figures 2A and 2B show a portion of the key according to the present invention, in particular an internal face or second face of the contact surface, in particular figure 2A shows the second face of the contact surface in the absence of this electrode; figure 2B shows the surface on which ? applied this electrode by pad printing;

- figures 3A and 3B show a capacitive key, according to the present invention, in different embodiments; in particular figure 3A shows the capacitive key in a first embodiment in which this connection element ? a coil spring; Figure 3B shows the capacitive key in a second, exemplifying and non-limiting embodiment, in which the connection element ? a column made of conductive silicone material.

With reference to the cited figures, the numeral 2 indicates the key of the capacitive type, according to the present invention, as a whole.

The key 2 of the capacitive type, according to the present invention, is capable of detecting the approaching and/or contact of a part of the body of a user ?U? on said key 2.

The key 2, according to the present invention, comprises: a contact surface 3, which ? adapted to be touched by a part of the body of a user ?U?, being able to impress a force on it. In particular, said contact surface 3 comprises a first face 3a, adapted to be touched by a part of the body of a user ?U? being able to impress on it a force, and a second face 3b, which ? opposite to said first face 3a.

The key 2, according to the present invention, further comprises an electrode 4 which ? adapted to be positioned below said contact surface 3. Said electrode 4 ? adapted to allow to detect the approach to and/or the touch of said contact surface 3 by a user ?U?.

The key 2, according to the present invention, further comprises a printed circuit 5. Said printed circuit 5 comprises one or more? electrical/electronic circuits. Said printed circuit board 5 ? electrically connected to said electrode 4.

The key 2, according to the present invention, further comprises a connection element 42. Said connection element 42 ? endowed with properties elastic. Said connection element 42 ? adapted to electrically connect said electrode 4 with said printed circuit 5.

The key 2, according to the present invention, comprises a support structure 6 which ? placed between said contact surface 3 and said printed circuit 5. Said support structure 6 ? at least capable of suitably positioning said connection element 42 between said electrode 4 and said printed circuit 5.

The key 2, according to the present invention, foresees that said electrode 4 ? made of transparent conductive material, especially electrical conductive. Said electrode 4 in transparent conductive material ? applied on said second face 3b of the contact surface 3 through a pad printing process.

The present solution allows to associate said electrode 4 with the contact surface 3 in a simple, rapid and safe way, and in particular with said second face 3b. This solution allows to make s? that said electrode 4 can always move integrally with said contact surface 3, avoiding the problems present in the solutions of the prior art.

For the purposes of this description, the term pad printing process means an indirect printing process, which allows you to apply, in a simple way and with high fidelity, and resolution of ONE desired substance on flat, concave, convex and/or in any case irregular surfaces, by means of a pad, preferably soft and flexible, for example made of silicone, which allows to apply a layer, for example a film of material , for example a resin, by transferring it to the desired surface.

Preferably, for each key 2, according to the present invention, said electrode 4 ? applied through a single pad printing process. This solution allows to further speed up the production and assembly of the key 2, according to the present invention.

In a preferred embodiment of the key 2, according to the present invention, said transparent conductive material applied to said second face 3b of said contact surface 3 to form said electrode 4 ? preferably an electrically conductive organic resin, for example ORGACON products? of the company? AGFA?, especially EL-P products, preferably EL-P3155. The materials indicated previously, cos? like others not explicitly indicated, they are all suitable for use in pad printing processes. In the preferred embodiment said pad printing process provides for a polymerization or hardening step of said resin on said second face 3b of the contact surface 3.

Pi? in general, in a possible embodiment of the key 2, according to the present invention, said contact surface 3 comprises a portion 3c that is at least partly transparent. Rays of light can pass through said transparent portion 3c, preferably at least in the direction from said second face 3b to said first face 3a. This solution makes it possible to provide keys 2 which can be backlit.

In the present embodiment, said electrode 4 being applied by pad printing can be placed in correspondence with said at least partially transparent portion 3c. In fact said electrode 4 ? made of transparent conductive material, therefore it allows the transit of light. Isn't that an advantage? obtainable in the embodiments of the prior art where such an electrode is made of metal or silicone material.

In key 2, according to the present embodiment where can? be backlit, said printed circuit 5 comprises at least one light source 52, for example LEDs. Dictate at least one light source 52 ? adapted to back-illuminate said contact surface 3, in order for example to bring out a distinctive sign or logo, placed in correspondence with said at least partly transparent portion 3c, suitable to allow the user to understand which function? associated with said key 2.

The electrode 4 of the key 2, according to the present invention, is electrically connected to the connection element 42, which ? in turn electrically connected to said printed circuit 5.

In the preferred embodiment of the button 2, according to the present invention, said connection element 42 divides said printed circuit 5 along an axis ?Z?. Said axis ?Z? ? perpendicular to the surface defined by said printed circuit 5, or said axis ?Z? ? perpendicular to the surface defined by said second face 3b of the contact surface 3.

Said connection element 42 has elastic characteristics, in particular being capable of exerting a force both on said contact surface 3 and consequently on said electrode 4, the latter being applied by pad printing on the second face 3b of the contact surface 3, which on said printed circuit 5. The force exerted by said at least one connection element 42 ? such as to ensure physical contact, in particular mechanical and electrical, between the electrode 4, applied by pad printing on the contact surface 3, and said printed circuit 5. Preferably, said connection element 42 exerts a force along the longitudinal axis of the same connection element 42.

Using an electrode 4 applied to the contact surface 3 by pad printing ? possible to detect the approach and/or the contact of a part of the body of a user ?U? in any configuration of the key 2 and/or of the contact surface 3, both in terms of shape and position in space, as well as guaranteeing a constant electrical connection between the electrode 4 and said printed circuit 5, without the need to of further conduction and/or support elements and/or connection between contact surface 3 and electrode 4.

The present solution allows to reduce the manufacturing and assembly times of the key 2, according to the present invention, ensuring in a simple way the electrical connection as well as the mechanical connection between the parts of the key 2.

In a possible embodiment of the key 2, according to the present invention, said connection element 42 ? a coil spring.

The present solution ensures the generation of a force sufficient to keep said connection element 42 mechanically in contact both on said printed circuit 5 and on said electrode 4, consequently guaranteeing the electrical connection between said electrode 4 and said printed circuit 5.

Said coil spring? for example placed in a housing made in said support structure 6.

In an alternative, exemplifying and non-limiting embodiment of the button 2, according to the present invention, said connection element 42 ? made of conductive silicone material. Said silicone connection element 42 has a longitudinal structure extending along an axis normal to said second face 3b of the contact surface 3 and/or of said printed circuit 5. Preferably, silicone connection element 42 has an oblong shape, for example cylindrical or in the shape of a parallelepiped. In a possible embodiment said conductive silicone ? a silicone doped with carbon powder. Possible alternative embodiments envisage that silicone or fluorosilicone materials are filled with particles of high conductivity, for example silver-plated aluminium, silver-plated copper, nickel-plated graphite, pure nickel, etc. These materials are suitable for operating over very wide temperature ranges and offer good quality? of compressive strength. In addition, fluorosilicone offers high resistance to solvents and hydrocarbons. In a further embodiment, said silicone material ? made conductive via a conductive outer layer, e.g. applied via paint.

In the present embodiment, said silicone connection element 42 incorporates an elastic element in the form of at least one silicone dome able to deform with properties elastic. Preferably, said cathedral being placed near? of one end of the connection element 42, for example near? of the electrode 4. The present solution makes it possible to guarantee the generation of a force sufficient to keep said connection element 42 mechanically in contact both on said printed circuit 5 and on said electrode 4, consequently guaranteeing the electrical connection between said electrode 4 and said printed circuit 5. This cathedral? made during the production process of said connection element 42, suitably making a mould.

In a preferred embodiment, said support structure 6 ? suitably constrained, for example mechanically, so as to move solidly with said contact surface 3.

In a possible embodiment of the key 2, according to the present invention, said contact surface 3 ? able to perform a movement along an axis ?Z? following the exercise of a force by a user ?U? on it. In this embodiment the key 2 therefore performs an excursion, and in particular the contact surface 3, when the latter is pressed, by applying a force thereon.

In an alternative embodiment, the position of said contact surface 3 ? invariable with respect to an external structure 11 in which said key 2 ? housed, not making excursions along said ?Z? axis. In this embodiment, the key 2 does not make any travel, not even the contact surface 3, when the contact surface 3 is touched by the user ?U?, by applying a force thereto.

In the embodiment of the key 2, according to the present invention, wherein said contact surface 3 ? adapted to perform a movement along an axis ?Z?, said connection element 42 ? adapted to deform elastically following a movement performed by said contact surface 3 due to a force exerted on the same contact surface 3.

In the present embodiment said connection element 42 ? designed in such a way as to influence as little as possible the sensory perception, in particular haptics, of the user ?U? which presses on the contact surface 3 of the key 2. Preferably, said connection element 42 ? designed to operate in a straight section of a force/displacement response, having a high displacement for a small applied force.

In the embodiment of the key 2, according to the present invention, wherein said contact surface 3 ? adapted to perform a movement along an axis ?Z?, between said support structure 6 and said printed circuit 5 ? there is a silicone dome 7.

In the present embodiment, said support structure 6 ? adapted to act on said silicone dome 7 in order to compress it. Said support structure 6 ? therefore able to slide along guides 12, preferably made in an external structure 11 in which the key 2 is housed.

Said silicone dome 7 ? able to selectively open and close an electric circuit, included on said printed circuit 5, according to the force applied thereon by said support structure 6. By collapsing said silicone dome 7 ? able to close an electric circuit, for example a normally open circuit, bringing for example electric contacts 8 into contact with each other.

Said silicone dome 7 ? preferably included in a silicone mat 72 which covers said printed circuit 5.

In a possible alternative embodiment of the key 2 and/or of the control keyboard 1, in addition or as an alternative to the silicone dome 7? there is a microswitch. This microswitch can? be operated by the same silicone dome 7, or be operated by said support structure 6.

In general, said silicone dome 7 and/or said microswitch ? able to provide a double feedback on the touch of key 2. In particular said silicone dome 7 and/or said microswitch ? capable of providing a further feedback of the electrical type in addition to the feedback provided by the capacitive circuit in relation to the pressure and/or contact of the contact surface 3 by a user ?U?. In particular, the electric circuit closed by said silicone dome 7 and/or said microswitch ? used as confirmation on the acquisition carried out by the capacitive circuit.

Said silicone dome 7 pu? it can also be used as an element to guarantee the mechanical return into position of the various parts of key 2, as well as contributing to the recovery of the play between the parts of said key 2.

The key 2 according to the present invention ? particularly suitable to be included in a control keyboard 1.

The control keyboard 1, according to the present invention, is a capacitive type control keyboard. The control keyboard 1 ? designed to detect the approaching and/or contact of a part of the body of a user ?U? on said control keyboard 1.

The control keyboard 1, according to the present invention, comprises an external structure 11. Said control keyboard 1 comprises at least one capacitive key 2 according to the present invention.

This external structure 11 ? suitable for housing said at least one key 2, providing, depending on the needs, guides 12 to allow movement of the contact surface 3 and/or of the support structure 6.

The present invention makes it possible to create a control keyboard 1 comprising at least one capacitive key 2 which, by implementing an electrode 4 according to the present invention, allows to simplify the construction and assembly of each key 2 included in said control keyboard 1.

Preferably, said control keyboard 1 comprises a single printed circuit 5 to which are suitably connected a plurality of of electrodes 4, for example an electrode 4 for each key 2 included in said control keyboard 1.

In a possible embodiment, said control keyboard 1 for each key 2 included therein? associated with a relative contact surface 3. In an alternative embodiment, said control keyboard 1 comprises a single contact surface 3 which ? in common for all the keys 2 included in it.

Preferably, said connection element 42 marginally affects any haptic effect perceived by the user ?U? if by pressing the key 2, and in particular the contact surface 3, it performs a movement such as to compress said silicone dome 7, influencing in a negligible way the feeling perceived by the user ?U? to compress at least one silicone dome 7. At the same time said connection element 42 ? designed to generate a pressure force both on the printed circuit 5 and on the electrode 4. In particular, the connection element 42 is designed in such a way as to guarantee a constant and pre-established minimum pressure force both on said electrode 4 and on said printed circuit 5.

Preferably, in the preferred embodiment, each key 2 ? associated with a specific function, suitably commanding a specific electronic circuit included on said printed circuit 5. In the embodiment of said control keyboard 1 comprising a plurality? of keys 2, each key 2 will have? a specific electrode 4, electrically isolated from the other electrodes 4 connected to the same printed circuit 5.

Figure 1 shows in a perspective view a possible embodiment of a control keyboard 1 which comprises at least one capacitive key 2, according to the present invention. The figure shows three keys 2 each having its own contact surface 3 on which the user ?U? can? exerting a force or approaching it. At each key 2 ? associated with at least one different function with respect to the 2 neighboring keys.

From figure 1 ? visible is a possible conformation of the external structure 11 adapted to be inserted in a suitable housing, for example in a passenger compartment of a vehicle or boat.

Figure 2A shows, by way of non-limiting example, the second face 3b of a contact surface 3 of a key 2, according to the present invention, in the absence of the electrode. The shape and structural characteristics of the contact surface 3 are purely illustrative for an immediate understanding of the generic concept underlying the invention. From this figure? visible the internal face or second face 3b of the contact surface 3, face which is not? visible following the assembly of the contact surface 3 in the key 2. In the illustrated embodiment, the contact surface 3 comprises a portion 3c which ? at least partially transparent, allowing the passage of light at least from said second face 3b towards said first face 3a.

Figure 2B shows substantially the same contact surface 3 shown in figure 2A, in particular said second face 3b, on which ? applied this electrode 4 by pad printing. For simplicity? of representation and understanding, although this electrode 4 ? made of transparent conductive material, this electrode 4 is shown with dotted portions to identify its location with respect to the remaining part of the second face 3b of the contact surface 3.

In the illustrated embodiment, said electrode 4 ? advantageously placed in such a way as to cover the greatest possible area of the second face 3b, also in correspondence with the transparent portion 3c, at least partially, of the contact surface 3, allowing to detect the approach and/or the contact of a part of the body of a user ?U? on any point of said first face 3a of the contact surface 3, as well as allowing to backlight said contact surface 3, for example to make visible a logo or symbol placed on said first face 3a of the contact surface 3.

Figure 3A shows, in a sectional view, a capacitive key 2, according to the present invention, in a first embodiment. In this first embodiment said connection element 42 ? a coil spring. From the figure ? visible the contact surface 3 on whose second face 3b ? electrode 4 applied. In contact with said electrode 4? present said connecting element 42 in the form of a helical spring. Below said contact surface 3 ? the support structure 6 is arranged for example to keep said connection element 42 in position, for example by aligning it with said axis ?Z?. From figure 3A ? further visible is a possible embodiment of the support structure 6 for the key 2 which ? houseable inside the external structure of a control keyboard, for example as illustrated in figure 1. Said support structure 6? able to slide along guides 12, for example for its assembly and/or in the case in which this contact surface 3 can move along said axis ?Z?.

In the illustrated embodiment said helical spring acts on said printed circuit 5. Said printed circuit 5 comprises at least one light source 52 which emits rays of light towards the second face 3b of the contact surface 3. Said contact surface 3 comprises a portion 3c at least partially transparent to allow the light emitted by said light source 52 to escape, backlighting said button 2. Although said electrode 4 overlaps at least partially with said portion 3c of the contact surface 3, being transparent, it allows the rays of light to transit continuing to guarantee a conductivity? electric. Advantageously, said button 2 comprises a silicone carpet 72 placed above the printed circuit 5.

Figure 3B shows, in a sectional view, a capacitive key 2, according to the present invention, in a second, exemplifying and non-limiting embodiment. In this second embodiment, the connection element 42 ? a column made of conductive silicone material. From figure 3B ? visible the contact surface 3 on whose second face 3b ? electrode 4 applied. In contact with said electrode 4? the connection element 42 made of silicone material is present and comprises a dome-shaped elastic element. Said cathedral? place near? of said electrode 4. Below said contact surface 3? placed the support structure 6 suitable for example to keep said connection element 42 in position. From figure 3B? further visible is a possible embodiment of the support structure 6 for the key 2 which ? housed inside the external structure of a control keyboard, for example as shown in figure 1.

In the illustrated embodiment, said support structure 6? placed in contact with a silicone dome 7, preferably made of a silicone mat 72. Said silicone dome 7 ? suitable for selectively closing electric contacts 8 included in said printed circuit 5. Said electric contacts 8 can be partly included in said silicone dome 7 or interposed between the silicone dome 7 and in the printed circuit 5, in the form of metal foils.

Said support structure 6 ? adapted to be moved due to a pressure impressed by a user ?U? on said contact surface 3. Preferably, said support structure 6? in contact with said contact surface 3. Said support structure 6 ? adapted to act on said silicone dome 7, compressing it until it collapses.

The embodiment illustrated in figure 3B shows a possible embodiment of the elastic element included in the connection element 42 which ? shaped like a dome, in its first possible embodiment, for example an upside-down dome.

The present embodiment comprises a contact surface 3 which ? adapted to perform a movement along an axis ?Z?. The movement along said axis ?Z? of the contact surface 3 of the button 2 ? assisted by said support structure 6. Said support structure 6 ? able to slide along guides 12, which are preferably made on the external structure 11. The force impressed on the contact surface 3 is adapted to move it, consequently moving the support structure 6. During this movement, the connection element 42 is? suitably compressed.

All the embodiments of the connection element 42 described and illustrated in the present patent application allow a force to be exerted both on the printed circuit 5 and on the electrode 4 applied to the contact surface 3, ensuring an electrical connection between said electrode 4 and said printed circuit 5, even in the case of movement along said axis ?Z? of the contact surface 3.

The present invention allows to associate said electrode 4 to the contact surface 3 in a simple, rapid and reliable way so that every movement of the contact surface 3, even in the case in which this contact surface 3 has complex shapes, is followed without continuity solution? from the electrode 4, also ensuring a stable electrical connection between the electrode 4 and the printed circuit 5.

The electrode 4, made of transparent conductive material applied by pad printing, allows to place this electrode also in correspondence with at least partially transparent portions adapted to allow the passage of light for backlit keys 2.

Alternative embodiments not illustrated and/or described which can be inferred from a person skilled in the sector in the light of the present description and from the attached figures must be considered as included in the scope of protection of the present invention.

NUMERICAL REFERENCES

Control keyboard 1 External structure 11 Guides 12 Button 2 Contact surface 3 First face 3a Second face 3b Portion 3c Electrode 4 Connection element 42 Printed circuit 5 Light source 52 Support structure 6 Silicone dome 7 Mat 72 Electrical contacts 8 ?Z axis ? User ?U?

Claims (10)

CLAIMS: 1. Key (2) of the capacitive type adapted to detect the approach and/or contact of a part of the body of a user (U) on said key (2); called key (2) ? comprising: - a contact surface (3), comprising a first face (3a) able to be touched by a part of the body of a user (U) being able to impress a force on it; and a second face (3b) opposite said first face (3a); - an electrode (4) able to be positioned under said contact surface (3); said electrode (4) being able to allow to detect the approach and/or the touch of said contact surface (3) by a user (U); - a printed circuit (5) comprising one or more? electrical/electronic circuits; said printed circuit (5) being electrically connected to said electrode (4); - a connection element (42), endowed with properties? elastic, able to electrically connect said electrode (4) with said printed circuit (5); - a support structure (6) placed between said contact surface (3) and said printed circuit (5) to suitably position said connection element (42) between said electrode (4) and said printed circuit (5); said key (2) being characterized in that said electrode (4) being made of transparent conductive material applied to said second face (3b) of the contact surface by means of a pad printing process. 2. Button (2) according to claim 1, wherein said connection element (42) is a coil spring. 3. Button (2) according to claim 1, wherein said connection element (42) is made of conductive silicone material, having a longitudinal structure extending along an axis normal to said second face (3b) of the contact surface (3); said silicone connection element (42) incorporates an elastic element in the form of at least one silicone dome adapted to deform with properties elastic. 4. Button (2) according to claim 1, wherein said electrode (4) is applied through a single pad printing process. 5. Button (2) according to one of the preceding claims, wherein said transparent conductive material applied to said second face (3b) of said contact surface (3) to form said electrode (4) ? an electrically conductive organic resin. 6. Button (2) according to one of the preceding claims, wherein said contact surface (3) comprising an at least partially transparent portion (3c) through which light rays can pass at least in the direction from said second face (3b) to said first face (3a); said electrode (4) being applied by pad printing at said at least partially transparent portion (3c); said printed circuit (5) comprising at least one light source (52) suitable for backlighting said contact surface (3). 7. Button (2) according to one of the preceding claims, wherein said contact surface (3) is adapted to perform a movement along an axis (Z) following the exertion of a force on it by a user (U). 8. Button (2) according to claim 7, wherein said connection element (42) is adapted to deform elastically following a movement performed by said contact surface (3), due to a force exerted on the same contact surface (3). 9. Button (2) according to claim 7, wherein between said support structure (6) and said printed circuit (5)? there is a silicone dome (7); said support structure (6) ? able to act on said silicone dome (7) in order to compress it; said silicone dome (7) ? adapted to selectively open and close an electric circuit included on said printed circuit (5) according to the force applied thereon by said support structure (6). 10. Control keyboard (1) of the capacitive type adapted to detect the approaching and/or contact of a part of the body of a user (U) on said control keyboard (1); called command keyboard (1) ? comprising an external structure (11); said control keyboard (1) being characterized in that it comprises at least one capacitive key (2), according to one of the preceding claims.