EP1920449B1 - Keyboard arrangement - Google Patents

Abstract

The invention relates to a keyboard arrangement, which simulates a key click by means of a snap disc (1) on closing an electrical contact. According to the invention, such keyboard arrangements may be flexibly and economically produced and also given a full screening against radiation by arranging the snap disc (1) above the perforation (2) with at least one of the webs (6) thereof fixed to one of the surfaces of the plate (3) and the diameter (Dl) of the domed snap disc (1) larger than the open cross-section of the perforation (2), such as to cover the same when fixed to the plate (3).

Description

The invention is concerned with keyboard assemblies which, prior to or during the manufacture of, for example, an electrical contact, by actuation of a button provided in the keyboard assembly, indicate to the user, by a tactile "switching click", the induction of the desired contact. Release the button and return it to its original position. Such keyboard arrangements are widely used and are used for example in remote controls for devices of the entertainment industry or in telephones.

This "peeling crack", which is also referred to as a pressure point, is generally realized by arranging a so-called snap disk below the respective knob. A snap-action disc is essentially arched components of metal or plastic which have a non-linear spring characteristic and which span a space, the head resting in its initial position on the zenith surface of the curved component. If a force acts on the button to trigger an electrical contact, the snap disc is elastically deformed by flattening the curvature. In doing so, the force required to flatten the snap disc increases slightly, and when the curl is pressed approximately flat, becomes smaller than the force needed to flatten it. If the curvature of the snap disc largely flattened, the spring direction of the snap disc reverses, whereby the force acting in this moment is less than the force required to flatten the curvature. The interaction of high and low actuation force or the reversal of the spring direction is then perceived by a user as a tactile feedback for triggering, for example, an electrical contact. If, in the flattened state, the force no longer acts on the button, it is returned to its original position by the elastic deformation of the snap-action disc. As can easily be seen, the flattening of the snap disc also causes a slight increase in its outer diameter. If this enlargement is prevented or even suppressed, there is a risk that the snap disc will not return to its original position.

Essentially, two technologies have emerged to form keyboards using snap domes. These technologies have in common that a plate is present, which has a plurality of openings and that this plate is arranged at a small distance above a board, wherein below each breakthrough on the board two mutually insulated contact surfaces are present. In addition, a snap disc is arranged in each of these openings, which connects under the action of a force on the knob, the two contact surfaces for making an electrical contact.

To make the connection of the snap disk is in accordance with the one in Fig. 1 shown technology, the respective snap disk 1 centrally disposed within a breakthrough 2 a plate 3 and the resulting due to the cross-sectional proportions of snap disk 1 and breakthrough 2 resulting radial distance with a suitable plastic material 4, whereby the snap disk 1 formed of metal elastically in the respective breakthrough is suspended. As can easily be seen, this technology is very expensive, since on the one hand the plate with the openings and the snap discs must be formed for example by punching and / or cutting and connected by means of another step, which does not belong to metal processing.

To reduce this effort is for example off US 4,343,973 a snap disk arrangement is known in which a formed of metal and having a curvature snap disc rests with its edge regions on a base formed of insulating material and covers a formed in the base cavity. Within the cavity there is disposed an electrical contact surface which comes into physical contact with the snap-action disc when the buckling of the snap-action disc is pressed downwards in the direction of the cavity.

Therefore, it has gone according to the other known technology to build the snap disc arrangement no longer made of different components, but to form the plate together with the snap discs in one piece of metal by appropriate punching and embossing steps are applied. For example, be on DE 19851534 and DE 3618131 directed. In order to ensure the necessary elastic suspension of the snap discs in the plate as well as to provide a sufficiently large space for the radial expansion of the respective snap disc under the pressure of the operated button, correspondingly large free cuts around the snap disc are required. With this technology, in addition to the complexity of such stamping tools permitting the integral formation of corresponding keyboard assemblies, it is also considered disadvantageous that any design change necessitates new stamping tools.

To produce the EMC criteria or to ensure a sufficient shielding against high-frequency radiation but such large free cuts or radial distances between breakthroughs and domes are not tolerable even if the respective spaces are filled with plastic.

The invention is therefore based on the object of specifying a keyboard arrangement which, in addition to high flexibility in the production and design changes, also forms a complete shield against high-frequency radiation.

Presentation of the invention

This object is achieved with the features specified in claim 1. The fact that the domes and the plates are made individually, these components can be manufactured with relatively simple punching and embossing tools and are very easily connected to complex units, for example by laser welding. The fact that the domes for a variety of applications can be made with one and the same set of tools, a very high degree of standardization is achieved. Since the diameter of the snap discs is always larger than the clear cross sections of the openings, it is ensured that the keyboard assembly according to the invention ensures complete shielding against unwanted frequencies by the complete coverage or the closure of the respective breakthrough with a snap disc, which are arranged from below the plate electrical components are emitted or act on these.

Depending on the application, the snap discs and the webs integrally connected to them made of metal or metallized plastic and electrically conductive with the plate be connected. By such a configuration, the formation of the arranged below the keyboard assembly electrical contacts per snap disk can be limited to a contact element.

Lying according to claim 2, the edge portions of the snap-action disc, which are not fixedly connected by means of the webs with the plate, slidably on the surface of the plate, it is ensured that a sufficiently large radial extent of the snap-action disc to bring about the "switching crack" is possible.

A reduction of the components is ensured according to claim 3, characterized in that at least two of a plurality of snap discs are connected by means of a common web to the plate. Depending on the design of the webs, it is also possible to form all the domes of a keyboard assembly in one piece.

Also other existing in the plate breakthroughs, which are required for example because of the height of components can be very easily closed frequency by means of snap discs according to claim 4 by also such breakthroughs are covered by "blind" snap discs. To avoid the damage of such components must then only be ensured that such snap discs are not in direct contact with any button in the keyboard.

In order to achieve a very stable connection of the snap discs with the plate, it is provided in claim 5, that each snap disc is fixedly connected by means of at least two webs with the plate, wherein each web used for stationary connection with the plate is provided with a hinge. In order not to interfere with the radial movement of the snap-action disc and to ensure the interplay between high force until flattening of the snap-action disc and low force near the flat state of the snap-action disc or upon reversal of the spring direction, it is essential that the joints of the radial movement of the snap-action disc only to apply a force that is substantially less than the force required to cause the flattening of the snap-action disc.

Lying the webs and their joints according to claim 6 on the surface of the plate, the joints of the radial extent of the snap disc can escape elastically, without having to worry that snaps when they are from their rest position is moved, lifts off the plate. As can be appreciated, is essential in the formation of the invention according to claim 5 and 6, that the stationary connection of the webs with the plate takes place in each case near the free ends of the webs.

If the snap disc according to claim 7 has a convex bead on its zenith surface, the curvature of which extends into the space spanned by the curvature of the snap disc, even large distances between the zenith surface and the contact surface (s) on the printed circuit board can be overcome.

The same applies to the embodiment according to claim 9, if to reduce the distance between the zenith surface or the bead and the one or more contact surfaces, the circuit board or conductor foil projects at least into the spaces that are surrounded by the openings.

Also allow the training according to claims 6 to 9 relatively thick, necessary for shielding plates without the function of the "switching crack" is lost.

Short illustration of the figures

• Fig. 1 eine Tastaturanordnung gemäß dem Stand der Technik im Seitenschnitt;
• Fig. 2a eine erfindungsgemäße Tastaturanordnung im Seitenschnitt;
• Fig.2b eine weitere Ausführungsform der Erfindung ebenfalls im Seitenschnitt;
• Fig.3a eine Draufsicht auf eine Tastaturanordnung gemäß Fig. 2a;
• Fig.3b eine weitere Ausführungsform einer Tastaturanordnung gemäß Fig. 3a;
• Fig. 4 eine weitere Ausführungsform einer Tastaturanordnung gemäß Fig. 3a;
• Fig.5 eine weitere Ausführungsform einer Tastaturanordnung gemäß Fig. 3a;
• Fig. 6 eine Kombination zweier Schnappscheiben gemäß Fig. 2a; und
• Fig.7 eine weitere Ausführung einer Schnappscheibe.

Show it:

• Fig. 1 a keyboard arrangement according to the prior art in side section;
• Fig. 2a a keyboard arrangement according to the invention in side section;
• 2b a further embodiment of the invention also in side section;
• 3a a plan view of a keyboard assembly according to Fig. 2a ;
• 3b a further embodiment of a keyboard arrangement according to Fig. 3a ;
• Fig. 4 a further embodiment of a keyboard arrangement according to Fig. 3a ;
• Figure 5 a further embodiment of a keyboard arrangement according to Fig. 3a ;
• Fig. 6 a combination of two domes according to Fig. 2a ; and
• Figure 7 another embodiment of a snap-action disc.

Ways to carry out the invention

The invention will now be explained in more detail with reference to FIGS.

With Fig. 2a a first embodiment of the keyboard assembly according to the invention is shown in its initial position. This keyboard assembly has a domed snap-action disc 1 made of metal, which is formed dome-shaped and spans the underlying space 5. This snap-action disc 1 is integrally connected to a web 6. Further, a metal plate 3 is also provided, which has an opening 2. The snap-action disc 1 is connected to the plate 3 only by means of the single web 6 by Laserscheißung X. In addition, below the plate 3, a printed circuit board 7 is shown, on which two electrical contact surfaces 8, 9 are arranged. Only for the sake of completeness, it should be noted that the in Fig. 2a shown mutual distance between the plate 3 and the circuit board 7 need not necessarily be present, but only for the sake of better illustration in Fig. 2a has been recorded.

How easily the representations according to the Fig. 2a and 3a can be removed, the diameter D1 of the snap-action disc 1 is greater than the clear cross-section D2 of the opening 2. This ensures that in each position of the snap disc 1 together with the plate 3 components in the direction of arrow P1 below the plate 3 and the snap disc 1 are arranged, shields.

If a force then acts in the direction of arrow P1 on the zenith surface Z of the snap-action disk 1, its curvature is flattened, whereby at the same time its edge expands in the radial direction P2. With progressive flattening, a point is reached where a noticeable "switching crack" is detected, at which the snap disc 1 slightly reverses its curvature direction present in the starting position. Since the snap disc 1 was only elastically deformed in its flattening, the snap disc 1 jumps into her Starting position back when the force in the direction of arrow P 1 is no longer effective. If the mutual distance between the contact surfaces 8, 9 or the printed circuit board 7 and the snap-action disk 1 is adjusted so that the deformed snap-action disk 1 rests against the contact surfaces 8, 9 or an electrically conductive connection is established between the contact surfaces 8, 9, when the "switching crack" is heard, the user receives with the "switching crack" a tangible confirmation that his keystroke has also led to the desired switching command.

In Fig. 2b Another embodiment of the breakthrough 2 covering the snap disk 1 is shown. Just like the in Fig. 2a shown snap disk 1 also vaulted the snap disk according to Fig. 2b the breakthrough 2 completely. However, since often the plate 3 must be made relatively thick to produce a suitable shield, it may happen that one according to Fig. 2a merely dome-shaped snap-action disc 1 in the production of an electrical contact already generates the "switching crack", although no electrical contact has been made. Therefore, the snap disk 1 according to Fig. 2b provided on its zenith surface Z with a curved bead 10, the curvature of which extends into the space 5, which is spanned by the snap disk 1.

As can easily be seen, the desired "switching crack" can be adjusted very flexibly and quickly to a given geometry of printed circuit board 7 and plate 3 by simply changing the ridge depth of the bead 10 in the space 5.

Also is Fig. 2b removable, that only a contact surface 8 'is arranged on the circuit board 7. In order to initiate an electrical contact with only one contact surface 8 ', when the snap disk 1 comes into physical contact with the contact surface 8', it is necessary for the snap disk 1 to lie "on ground". Since the snap disk 1 according to Fig. 2b formed of metal and connected to the plate 3, which is also made of metal, this is solved in the present case, that in the embodiment according to Fig. 2b the plate 3 is "on ground".

It should also be noted that in the embodiments according to Fig. 2 a and b, the circuit board 7 may be formed as a conductor foil.

Also shows Fig. 2b another snap-action disc 1 ', which is juxtaposed to the snap-action disc 1, and which, like the snap-action disc 1, is capable of producing a "switching crack" to create. However, in Fig. 2b this snap disk 1 'is not used for generating a "switching crack" when performing an electrical contact, but only serves the shielding of a component 12 on the circuit board 7, which protrudes because of its height from the plate 3.

As the representations according to Fig. 2b and Fig. 6 can be removed, the two snap discs 1 and 1 'are connected by means of a common web 6 by laser welding X. For the sake of completeness, it should be pointed out that two snap disks 1, which are each arranged above contact surfaces 8 ', can also be connected to the plate 3 by means of a common web 6. In such a case would be in Fig. 2b or 6, the component 11 is replaced by at least one contact surface 8 '.

In Fig. 3b is shown another form of the web 6, with which the snap disc 1 is connected to the plate 3. In contrast to the straight bar 6 according to 3a is the jetty according to Fig. 3b formed serrated, the jaw forms a hinge 11. In order to ensure the elastic spring action of resting on the plate 3 joint 11 under the action of the radial expansion of the snap disk, the webs 6, as in Fig. 3b and Fig. 4 shown near its free ends to the plate 3 by laser welding X connected.

In Fig. 5 a combination of four snap discs 1 is shown, which are arranged above corresponding openings 2. All four snap discs 1 are integrally connected to each other via common webs 6 and can therefore be made in a punching pass.

Unlike the embodiment according to Fig. 2a is in Fig. 7 instead of a printed circuit board 7, a conductor foil 7 'available. In order to reduce the distance between the zenith surface Z of the snap-action disk 1 and the contact surface 8 ', the conductor foil 7' projects into the space 12, which is bordered by the opening 2. Finally, it is still too Fig. 7 added that the execution according to Fig. 7 not necessarily conductor foils 7 'required and that the bead 10 shown in another embodiment of Fig. 7 can also be completely eliminated. However, if a conductor foil 7 'is used, the apertures 2 should be conical in order to reduce wear.

Claims (9)

1. Keypad arrangement
   having a plate (3) which is formed from an electric current-conducting material and which has at least one aperture (2), and
   having a curved snap-action disc (1) which has at least one web (6) which is integrally connected to it,
   characterized
   in that the snap-action disc (1) is arranged above the aperture (2) and is connected by way of at least one of its webs (6) to one of the two surfaces of the plate (3) in a fixed and electrically conductive manner, and
   in that the diameter D1 of the curved snap-action disc (1) is greater than the clear cross section D2 of the aperture (2), as a result of which the said curved snap-action disc fully closes the aperture in the state in which it is connected to the plate (3).
2. Keypad arrangement according to Claim 1,
   characterized
   in that the webs (6) or edge regions of the snap-action disc (1) which are not connected to the plate (3) in a fixed manner rest on the surface of the plate (3) in a moveable manner.
3. Keypad arrangement according to either of Claims 1 and 2,
   characterized
   in that at least two of a plurality of snap-action discs (1) are connected to the plate (3) by means of a common web (6).
4. Keypad arrangement according to one of Claims 1 to 3,
   characterized
   in that all other apertures (2) in the plate (3) are covered by a snap-action disc (1') too.
5. Keypad arrangement according to one of Claims 1 to 4,
   characterized
   in that each snap-action disc (1) is connected by way of at least two webs (6) to the plate (3) in a fixed manner, and
   in that each web (6), which is used for connection to the plate (3), has a joint (11), with the joints (11) providing a radial expansion of the snap-action disc (1) with only a force which is significantly lower than the force which is required to flatten the snap-action disc (1).
6. Keypad arrangement according to Claim 5,
   characterized
   in that the webs (6) and their respective joints (11) rest on the surface of the plate (3) and, when the snap-action disc (1) is radially expanded, elastically deflect this radial expansion.
7. Keypad arrangement according to one of Claims 1 to 6,
   characterized
   in that the respective snap-action disc (1) has a zenith area Z, and
   in that the zenith area Z is provided with a curved corrugation (10), with the curvature of the corrugation (10) extending into the space (5) which is spanned by the curvature of the snap-action disc (1).
8. Keypad arrangement according to one of Claims 1 to 7,
   characterized
   in that each snap-action disc (1) has at least one associated contact element (8, 9, 8'), and
   in that the contact elements (8, 9, 8') are arranged on a printed circuit board (7) or flexible printed circuit (7').
9. Keypad arrangement according to Claim 8,
   characterized
   in that the printed circuit board (7) or the flexible printed circuit (7') projects at least into the spaces which are bordered by apertures (2).

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