EP1215696B1 - Keypad assembly for an electrical device - Google Patents

Description

The present invention relates to a keyboard assembly for an electronic device, in particular for a mobile electronic device, such as a mobile terminal, comprising at least one keymat with at least one operating element, wherein the at least one operating element on an actuating side of the at least one keypad mat projects and the at least one operating element is provided on one of the actuating side remote contact side with electrically conductive contact means, wherein further the operating element is displaceable when pressurized from a rest position to a contact position, in which at least two associated electrical contacts of an electronic circuit via the contact means electrically connected or are connected.

Such a keyboard arrangement is known from the prior art, such as from US-A-4710597 , For a more detailed explanation of this prior art, reference is made to FIG JP 100 120 88-A equivalent. FIG. 6 shows a keyboard arrangement 210 according to the prior art. This keyboard assembly 210 is modular and includes a keyboard mat 212 on which key elements 214 are formed. The keypad mat 212 is adhesively bonded to a polycarbonate foil 216, wherein this polycarbonate foil 216 in the region of the key elements 214 of the key mat has dome-shaped elevations 218 which are embossed into the polycarbonate foil 216. On the side facing away from the keyboard mat 212 side of the polycarbonate sheet 216, a spacer plate 220 is disposed with openings in the region of the cap 218. From this, the keyboard assembly 210 is connected via a connecting layer 222 to a printed circuit board 224, which is mechanically reinforced by a reinforcing plate 226. at Pressurization of the key element 214 according to arrow P in Figure 6, the key element is moved down to the top of the dome 218 associated therewith and exerts pressure on this dome 218 from. Under the action of this compressive force, the dome 218 bends from its initial position shown in FIG. 6 by a solid line into a deflection position shown by a dotted line in FIG. 6 and designated by 218 '. The polycarbonate foil 216 is provided on its side facing away from the keypad mat 212 at least in the region of the calottes 218 with a contact lacquer, for example of a graphite-silver mixture or the like. In the deflection position 218 ', the surface of the dome provided with the contact lacquer touches the printed circuit board and can thus electrically connect two contacts 228a and 228b extending on the printed circuit board. After cancellation of the pressurization, the key element 214 moves back to the starting position shown in Figure 6. Likewise, the cap 218 moves from the deflection position according to 218 'back to the starting position. As a result, the electrical connection between the two contacts 228a and 228b is canceled.

However, such a sandwiched keyboard arrangement according to the prior art of Figure 6 has significant disadvantages. Due to the modular structure of several layers, namely keyboard mat 212, PC film 216 and spacer plate 220, the production of the keyboard assembly 210 is relatively expensive and costly, especially because the PC film is at least partially still additionally provided with the contact lacquer. Replacing the PC film 216 with a metal dome plate to thereby improve the operational reliability further increases the manufacturing cost of the prior art keyboard assembly. Moreover, the keypad assembly 210 of the prior art shown in FIG. 6 suffers from the problem that due to the deflection of calottes on the circuit board 224, only very small ones are involved geometric distances for making an electrical connection between the two contacts 228a and 228b can be bridged. Therefore, it is necessary to use in the manufacture of the circuit board 224 techniques and materials that allow an arrangement of different conductors or different contacts with a very small distance, even in mass production. To ensure this, it is necessary to use costly printed circuit board manufacturing techniques or valuable conductive material materials such as gold. This additionally increases the manufacturing costs of an electronic device formed with the keyboard arrangement according to FIG. Due to the small dimensions required for the production of the electrical connection between the contacts 228a and 228b, the further problem arises that the keyboard arrangement and the circuit board associated therewith become very sensitive to external influences, in particular contamination. If, for example, dust settles in the area of the contacts 228a, 228b, sufficient contact with the deflected dome 218 'is no longer guaranteed.

It is accordingly an object of the present invention to provide a keyboard assembly of the type described, which ensures a reliable and insensitive to external influences operation with simple and inexpensive production in conjunction with inexpensive printed circuit boards conventional design.

This object is achieved by a keyboard arrangement according to claim 1.

Instead of modularly constructing the keyboard assembly in sandwich construction, as described above with reference to Figure 6 to the prior art, the invention provides that the keypad is provided in the region of at least one operating element on its contact side with a contact body of electrically conductive, elastically deformable material. This makes it possible to electrically conduct over a relatively large area an electrical connection between two electrical contacts of an electronic circuit, for example, on the circuit board, and this with a simple construction of the keyboard assembly, since this comprises only the Tasturmatte and contact body formed thereon. Furthermore, at the same time a reliable and against deposition of dust or dirt particles on the circuit board insensitive functioning of the keyboard assembly is guaranteed. If, for example, one imagines that dust deposits in the area of the electrical contacts of the electronic circuit to be connected, as described at the beginning with reference to the prior art, the contact body presses on the dust particles but deforms under the elasticity Pressurization by means of the operating element such that it touches the electrical contacts to be connected despite the dust particles and thus provides an electrically conductive connection. The possibility of using the invention also Further, electrically bridging larger pitches further improves the cost situation with respect to the printed circuit boards to be used since conventional printed circuit boards can now be used that can be manufactured using standard techniques and less expensive materials, such as graphite traces. With the solution according to the invention, it is possible to electrically connect electrical contacts or conductor tracks which are arranged at a distance of up to 6 mm on the printed circuit board, by a correspondingly dimensioned contact body.

With regard to the choice of material for the contact body can be inventively provided that this is made of an electrically conductive elastic plastic material, preferably made of an electrically conductive soft elastic rubber material, in particular of electrically conductive silicone material. Such a choice of material provides for a reliable operation of the keyboard assembly with a long service life. In addition, the materials mentioned are available at low cost and easy to handle in manufacturing without the need for special precautions.

In the above, indications have already been given of a possible dimensioning of the contact body. With regard to the geometric shape of the contact body can be inventively provided that it has a substantially cylindrical or bulbous shape, preferably substantially circular cylindrical shape, and is fixed with one of its bases on the contact side of the control element. It may also include conical sections to facilitate assembly. If the contact body is then pressed upon pressurization together with the operating element on the electronic circuit, it may deform accordingly, wherein - as already stated above - the elastic material evades any existing dust particles and which increases correspondingly under the pressurization of the contact surface.

In a further development of the keyboard arrangement according to the invention can be provided that the at least one operating element is integrally formed on the keypad mat. The formation of the at least one operating element integrally on the keypad mat makes it possible to produce the keypad assembly as a unitary assembly, whereby the further assembly of the keyboard assembly or provided with this electronic device is simplified.

Furthermore, the invention can be provided that the at least one operating element is connected via a resilient connection region with the keypad mat, wherein the at least one operating element is displaceable under pressure of elastic deformation of the connecting portion against a spring force from the rest position to the contact position and when canceling the pressurization automatically moved back to the rest position. Such a design of the keypad mat is required in comparison with the prior art described in relation to FIG. 6 in particular because the spring action of the deflected calottes is no longer present in the present invention. The restoring action according to the invention can be achieved, for example, in that the resilient connection region is formed with a small wall thickness and narrows from the keypad mat to the operating element. In such a design of the keypad deformed under pressure, only the resilient connection region, so that a targeted displacement between the rest position and contact position can be achieved. Advantageously, the keypad mat made of soft elastic material, preferably made of rubber, in particular made of silicone. This choice of material ensures reliable operation and good tactile properties of the keyboard mat controls with low material and manufacturing costs. This is the case in particular if the at least an operating element is designed as a push button.

In a further development of the invention can be provided that the keypad comprises a plurality of grouped controls and that this plurality of control elements is assigned a common key element, wherein the key element is tumble when pressurized and / or depressible and wherein upon pressurization of the common key element at least an associated this control element from the rest position is displaced into the contact position. Such a wobbling movable and / or depressible key element allows easy operation of complex menu structures of the electronic device. This is necessary, for example, in mobile radio terminals, which are equipped with ever more comprehensive functions, which can be selected via hierarchical menu structures. The invention is particularly suitable for a reliable constructive realization of such key elements with low production costs and low production costs. Namely, in connection with a key element associated with a plurality of operating elements, it has been found that problems may arise due to the increasing miniaturization of corresponding electronic devices due to the structural design of the prior art keypad assembly as described with reference to FIG are. Due to the greatly simplified structure of the keyboard assembly according to the present invention, these problems can be overcome, and a key element associated with a plurality of operating elements can be further miniaturized without loss of function together with the electronic device.

If one executes the above-mentioned key element, for example, as a so-called navigation key, with which a navigation in four or possibly eight in regular Angular distances over 360 ° distributed directions should be possible, it can be provided in a development of the invention that the key element four controls are assigned, wherein the four controls are arranged in the region of the vertices of the contour of the key element inscribed square. An ergonomic operation and an attractive visual appearance results in this variant of the invention, for example, when the key element has substantially circular contour.

In order to arrange the additional key element safely and protected against unwanted displacement on the keypad, can further be provided according to the invention that each of the key element associated controls has a shaft portion and that the key element has corresponding recesses, which for the storage of the key element on this associated control elements respectively pick up a shaft section. In order to achieve good haptic properties for the key element, can be further provided according to the invention that the key element of a rubber material, preferably made of silicone and / or preferably with higher hardness than the keypad mat and / or the contact body is made.

The invention further relates to an electronic device, in particular a mobile electronic device, such as a mobile radio terminal, comprising a keyboard arrangement according to one of the preceding claims.

Figur 1

eine perspektivische Ansicht einer erfindungsgemäßen Tastaturanordnung;

Figur 2

eine Draufsicht der Tastaturanordnung gemäß Figur 1;

Figur 3

eine perspektivische Ansicht der Tastaturanordnung gemäß Figur 1, wobei jedoch ein zusätzliches Tastenelement weggelassen wurde;

Figur 4

eine Schnittdarstellung gemäß der Schnittlinie IV-IV aus Figur 2;

Figur 5

eine Vergrößerung des in Figur 4 mit V bezeichneten Bildausschnitts und

Figur 6

eine Teilschnittdarstellung durch eine herkömmliche Tastaturanordnung nach dem Stand der Technik.

In the following an embodiment of the present invention will be explained with reference to the accompanying figures. They show:

FIG. 1

a perspective view of a keyboard assembly according to the invention;

FIG. 2

a plan view of the keyboard assembly of Figure 1;

FIG. 3

a perspective view of the keyboard assembly of Figure 1, but with an additional key element has been omitted;

FIG. 4

a sectional view taken along section line IV-IV of Figure 2;

FIG. 5

an enlargement of the image detail designated by V in FIG

FIG. 6

a partial sectional view through a conventional keyboard arrangement according to the prior art.

In FIG. 1, a keyboard arrangement according to the invention is designated generally by 10. This is for installation in an electronic device, not shown, in the example, a mobile terminal, provided and includes a keyboard mat 12. From the keypad mat 12, in particular from the actuation side 14 of several jump control elements 16 before, which are designed as push buttons. Furthermore, the keyboard assembly 10 includes a key element 18 which is tiltable about the tilt axes A and B shown in Figure 2 in a total of four tilting directions. In the right in Figure 1 middle portion of the keyboard assembly 10, a skirt 20 is provided with a central opening 22, in which a microphone can be used. Further, in the keypad mat 12 recesses 24 in the immediate vicinity of the enclosure 20 and notches 26 are provided which serve to fix the keypad mat 12 in the electronic device, not shown. The keypad mat 12 is made of a soft elastic silicone material, wherein the push buttons 16 are integrally formed with the keypad mat 12.

In FIG. 3, the keypad mat 12 is shown omitting the key element 18. This figure shows that the key element 18 is mounted on four control elements 28. Each operating element 28 comprises a pin-shaped shaft 30, a substantially circular-cylindrical flange 32 and a conical connecting portion 34, via which the control element 28 is connected to the keypad mat 12.

The exact structure and operation of the controls 16 and 28 will be described below by way of example with reference to Figures 4 and 5 for a control element 28. 2 shows the keyboard arrangement according to the invention together with the wobbling movable key element 18. This is mounted on the four arranged at corners of a square controls 28 in parallel to the actuating side 14 of the keyboard assembly 10 not displaceable manner , For this purpose, the key element 18 recesses 36, in each of which a shaft 30 of an operating element 28 is inserted. To facilitate insertion of the controls 28 in the recesses 36 during assembly, the controls 28 are conically formed at their keyboard matte distal ends 38. The key element 18 lies with its underside 40 on a step surface 42 of each operating element 28, wherein the step surface 42 results from the transition from the shaft 30 to the flange 32.

FIG. 5 also shows how the connecting region 34 connects the operating element 28 to the keypad mat 12. As is also apparent from FIG. 3, the connecting region 34 is configured as a truncated cone with a small wall thickness. On the side 14 facing away from the actuating side 14, a pill-shaped contact body 46 is formed below each operating element. This contact body 46 is made of conductive silicone low (Shore A) hardness. The contact body 46 is fixed to the contact side 44 of the keypad mat 12 in the region of the operating elements 28 by gluing. If, for example, one presses on the key element 18 in accordance with the arrow P according to FIG. 5, then the operating element is displaced out of its rest position shown in FIG. 5 while deforming the connecting region 34 into a contact position. In this contact position is the Contact body 46 in mutual contact with a dashed line in Figure 5 shown circuit board 48, on which an electronic circuit is realized. In mutual mechanical contact between the printed circuit board 48 and contact body 46, this bridges the distance between two electrical, implemented on the circuit board contacts 50 and 52 and thus provides for an electrical connection of these contacts. If the pressurization according to arrow P is canceled, ie the key element 18 is released again, it moves automatically with the forming of the connection region 34 back to its starting position, wherein the contact body 46 is lifted from the circuit board 48 and the control element 28 together with the contact body 46 in the Return to rest shown in Figure 5.

The invention shows, compared to the prior art shown in Figure 6, a much simplified keyboard assembly, which is inexpensive to produce and provides high reliability. If, again referring to FIG. 5, the situation is that dust deposits are present in the region of the two contacts 50, 52 of the printed circuit board, the invention permits a secure electrical connection of the two contacts 50, 52 despite these dust deposits Contact body 46 under the pressurization according to arrow P deformed due to its soft elastic material properties and thus dodge deposits and can provide a reliable contact of the contacts 50 and 52. Furthermore, two adjacent control elements 28, as shown in Figure 5, can be arranged in close proximity to each other, without their operation would be affected. Thereby, a further miniaturization of the keyboard assembly in accordance with a required miniaturization of the associated electronic device is possible. Moreover, the invention can be due to the relatively simple structural design, the cost available materials for the realization of the invention and the favorable properties in terms of contacting Of PCB contacts achieve significant savings in the production of the keyboard assembly according to the invention and in the use of corresponding circuit boards.

Claims (13)

1. Keypad arrangement for an electronic device, in particular for a mobile electronic device, such as a mobile radio terminal for example, comprising at least one keypad mat with at least one operating element, with the at least one operating element projecting from the at least one keypad mat on an activation side and with the at least one operating element being provided with electrically conducting contact means on a contact side facing away from the activation side, it being possible also for the operating element to be displaced from a rest position to a contact position when pressure is applied, in which contact position at least two electrical contacts assigned to it in an electronic circuit can be connected or are connected in an electrically conducting manner by way of the contact means, characterised in that at least three operating elements are provided, of which at least one is configured as a key (16) and at least two are configured as an operating element (28) having a shaft segment (30) for an assigned key element (18) with recesses (36) corresponding to the respective shaft segment (30), which recesses (36) each accommodate a shaft segment (30) to support the key element (18) on the operating elements (28) assigned to it.
2. Keypad arrangement according to claim 1, characterised in that the contact means comprise a contact body (46) made from an electrically conducting, elastically deformable material and assigned separately to the respective operating element (16, 28).
3. Keypad arrangement according to claim 1 or 2, characterised in that the contact body (46) is made from an electrically conducting elastic plastic material, preferably an electrically conducting highly flexible rubber material, in particular an electrically conducting silicone material.
4. Keypad arrangement according to one of claims 1 to 3, characterised in that the contact body (46) has an essentially cylindrical or bulbous form, preferably an essentially regular cylindrical form, and is fixed by way of one of its base surfaces to the contact side (44) of the operating element (16, 28).
5. Keypad arrangement according to one of the preceding claims, characterised in that the at least three operating elements (16, 28) are configured in an integral manner on the keypad mat (12).
6. Keypad arrangement according to one of the preceding claims, characterised in that the at least three operating elements (16, 28) are connected to the keypad mat (12) by way of a resilient connecting region (34), it being possible for the at least three operating elements (16, 28) to be displaced counter to a spring force from the rest position to the contact position when pressure (P) is applied, causing the connecting region (34) to be subject to elastic deformation, and moving back automatically into the rest position when the pressure (P) ceases to be applied.
7. Keypad arrangement according to claim 6, characterised in that the resilient connecting region (34) is configured with a small wall thickness and narrows from the keypad mat (12) to the operating element (16, 28).
8. Keypad arrangement according to one of the preceding claims, characterised in that the keypad mat (12) is made from a highly flexible material, preferably rubber, in particular silicone.
9. Keypad arrangement according to one of the preceding claims, characterised in that the keypad mat (12) comprises a plurality of operating elements (28) disposed in a grouped manner and that this plurality of operating elements (28) is assigned a common key element (18), it being possible for the key element (18) to be moved and/or pressed down in a tumbling manner when pressure (P) is applied and it being possible for at least one operating element (28) assigned to the common key element (18) to be displaced from the rest position to the contact position when pressure (P) is applied to said common key element (18).
10. Keypad arrangement according to claim 9, characterised in that four operating elements (28) are assigned to the key element (18), the four operating elements (28) being disposed in the region of the corner points of a square inscribed in the contour of the key element (18).
11. Keypad arrangement according to claim 9 or 10, characterised in that the key element (18) has an essentially circular contour.
12. Keypad arrangement according to one of claims 9 to 11, characterised in that the key element (18) is made from a rubber material, preferably silicone or/and preferably with greater hardness than the keypad mat (12) or/and the contact body (46).
13. Electronic device, in particular a mobile electronic device, such as a mobile radio terminal for example, comprising a keypad arrangement (10) according to one of the preceding claims.

Images