EP1355332B1 - Electric contact device and corresponding keyboard - Google Patents

Description

The invention relates to an electrical contacting device with electrical contact points on a movable, substantially plate-shaped carrier and with these opposite fixed contacts, which contact the contact points after a switching movement of the carrier. The invention further relates to a keyboard with such a contacting device.

Such a contacting device is usually used in electronic devices, in switching devices and in particular command devices. For operating electronic devices, e.g. Programmable controllers in the automation industry, a variety of compact flat short-stroke keys and keypads have been developed in addition to known bulky mechanical control devices with large actuation paths. The latter belong to the family of short-stroke pushbuttons and membrane keyboards and are very compact.

The known contacting devices usually have a snap action and an electronic contact. The snap action is often realized by a, for example metallic, snap element that changes its shape abruptly under pressure load, thereby closing the switch contact. When the pressure decreases, the snap element returns to its rest position, whereby the switching contact is opened again. This mechanical effect is known from a "crackpot frog" ago. However, the strict requirements for safe operation in harsh industrial environments can not be met by these keys. Thus, such safe switches must neither wear out during operation nor fail, or a failure must be detected by the safe electronic control. Also, the electrical path to the control must be safe. Depending on the safety category is This can be achieved by sufficiently wear-free and failure-free pushbuttons in conjunction with at least two-pole simultaneous galvanically isolated switching. A probe with high robustness and freedom from wear offers the contact element described in US Pat. No. 5,990,772. As shown in FIG. 1, the probe 1 disclosed here comprises a substrate 2 with a pair of spaced stationary switching contacts 3, which are to be bridged by an electrically conductive armature 4. The armature 4 has a central axis with first and second raised contacting areas on both sides of the axis. In the non-actuated state, the armature 4 is held by the attractive force of a magnetic layer 5 and spaced apart from the switching contacts 3. Between the magnetic layer 5 and the substrate 2 is an insulating spacer layer 6 with an opening 7, in the region of the armature 4 is added. The armature 4 designed as an electrically conductive metal disk is movable by an actuating force for contacting with the switching contacts 3. As a result of the operation of the armature 4 first breaks its one side away from the magnetic layer 5 and contacts the one of the two switching contacts 3. Subsequently, the armature 4 rotates about that of the side, which is still in communication with the magnetic layer 5, opposite side, to This page also breaks away from the magnetic layer 5 by the actuating force to contact the second switching contact 3. In this way, the two switching contacts 3 are bridged electrically conductive. However, the armature 4 described here as a contact element as well as all other elements known hitherto are not suitable for simultaneously actuating several galvanically isolated circuits simultaneously.

From US 5,552,571, which takes the priority of DE 41 13 180 C1, a push-button-operated switch is known. This has a switch socket with a guide bore into which engages the guide pin of a plate-shaped, movable contact carrier. This is a serving as a push button switch cap. About this, the plate-shaped, movable contact carrier and its guide pin can be pressed against the force of a disc spring against a set of four annular contacts which are arranged concentrically around the guide bore and the guide pin in a fixed contact carrier on top of the switch socket. On the underside of the movable contact carrier further annular contacts are arranged concentrically to the guide pin. These contact the contacts on the fixed contact carrier when the movable contact carrier has been actuated via the pushbutton. In each case, two of the fixed annular contacts are short-circuited by an annular contact on the underside of the movable contact carrier, so that a normally open contact is realized.

From US 4,400,594 a keyboard for electrical or electronic devices is also known. This has a carrier plate with a plurality of holes through which the shafts of push buttons are passed. On the underside of the support plate discs are attached to the shafts of the push buttons, on the inside surface contacts are attached. These contact with corresponding mating contacts, which are located on the underside of the carrier plate. On the underside of the carrier plate, a layer of a magnetic elastomer is further applied. This causes an attraction on the discs of the push buttons in the manner of a restoring force.

Furthermore, electronic devices are increasingly expected to provide electronic pre-processing of the signals. For this purpose, appropriate components including their electrical interconnection are preferably required in or on the command device. The Kurzhubtasten offer in its interior so far only limited possibilities, such as. the integration of a light emitting diode. Also, for proper illumination of the actuating surface of the switching element, electronic components are preferably needed in the interior of the element.

In order to create several galvanically isolated contacts, you had previously resort to large mechanical command devices or press several separate short-stroke keys in parallel. The required for the safety functions simultaneous switching within a very short time window can be achieved only with great additional effort with a simultaneous snap-action function according to the technical concept of emergency-stop buttons. However, this solution contradicts the required robustness and reliability and is very bulky. For setup operation, e.g. also combinations of so-called release buttons with one or more other commanders for setting up machines before.

The positioning of the necessary electronic components is usually next to the short-stroke on the circuit board there, but this requires extra space and in the case of internal illumination of such an element cumbersome light guides required. The illumination is only selectively or very unevenly accessible.

From DE 100 40 151 C1, a membrane keypad is known in which frequently used push-buttons are executed in a "click-frog technology", ie show a snap switching behavior mediated by a snap element. In contrast, less frequently used buttons are designed in a low-cost "switching bubble technology". In the case of the latter, the front foil of the keyboard is bulged outward in the area of the keypad to form a "switching bubble". The inner surface of the front foil is provided in the area of the switching bladder with a, usually printed, contact surface, which faces in the rest position by far one or more fixed contacts. For operation, the front foil is in the area of the switching bladder pressed. The switching bubble is thereby "dented", so to speak, with the contact surface pressed against the one or more fixed contacts, and the switching contact is thus closed. When the actuation pressure is withdrawn, the front foil returns to its bubble-like starting position, the switching contact being opened again. The known keyboard is inexpensive to manufacture by the use of simple but weary button-like buttons, with premature wear of the frequently used button is avoided by the local use of the more complex, but durable snap element button. For safety-related switching operations, however, the known keyboard is not suitable.

The invention is therefore an object of the invention to provide an electrical contacting device of the type mentioned above, which avoids the disadvantages mentioned above with a simple structure and cost-effective design. Furthermore, a particularly suitable keyboard should be specified with such a contacting device.

With respect to the contacting device, the object is achieved by the features of claim 1. With respect to the keyboard, the object is achieved by the features of claim 12. Thereafter, within a keyboard at least a first keypad associated with an inventive contacting device. Furthermore, at least one second keypad is associated with a pushbutton in the form of a short-stroke switching element, which is executed in the manner of a bladder-like circuit or has a snap switching behavior mediated by a snap element. In this case, the first keypad or the first keypads are provided for safety-related switching operations, while the second keypad or the second keypads are intended for non-safety-related switching operations.

The term keypad is understood to mean a tactile area which is marked on the user interface of the keyboard and to which an underlying button or a contacting device is assigned. Pressurization of the user interface in the area of a keypad leads to actuation of the corresponding button or the corresponding contacting device.

FIG 2,3,4

mehrere Ansichten eines Trägers mit Öffnerkontakten einer erfindungsgemäßen elektrischen Kontaktierungseinrichtung,

FIG 5,6,7

die Schaltpositionen des Trägers gemäß FIG 2, 3, 4,

FIG 8,9,10

mehrere Ansichten eines Trägers mit Schließerkontakten einer erfindungsgemäßen elektischen Kontaktierungseinrichtung,

FIG 11,12,13

die Schaltpositionen des Trägers gemäß FIG 8, 9, 10,

FIG 14,15

mehrere Ansichten eines Trägers mit einem Öffner- und einem Schließerkontakt einer erfindungsgemäßen elektrischen Kontaktierungseinrichtung,

FIG 16,17,18

die Schaltpositionen des Trägers gemäß FIG 14, 15,

FIG 19,20,21,22

mehrere Ansichten eines Trägers mit einer Schaltung einer erfindungsgemäßen elektrischen Kontaktierungseinrichtung,

FIG 23

in Draufsicht eine Kontaktierungseinrichtung gemäß FIG 5 umfassende Folientastatur und

FIG 24

in einem schematischen Querschnitt XXIV-XXIV die Tastatur gemäß FIG 23.

Advantageous development of the invention can be found in the dependent claims. Further embodiments of the invention are explained in more detail below with reference to the following drawings. Show it:

FIGS. 2,3,4

several views of a carrier with NC contacts of an electrical contacting device according to the invention,

5,6,7

the switching positions of the carrier according to FIG 2, 3, 4,

8,9,10

several views of a carrier with normally open contacts of an inventive electrical contacting device,

FIGS. 11,12,13

the switching positions of the carrier according to FIG 8, 9, 10,

FIG

several views of a carrier with a normally closed and a normally open contact of an electrical contacting device according to the invention,

FIGS. 16, 17, 18

the switch positions of the carrier according to FIGS. 14, 15,

FIGS. 19, 20, 21, 22

several views of a carrier with a circuit of an electrical contacting device according to the invention,

FIG. 23

in plan view a contacting device according to FIG 5 comprehensive membrane keypad and

FIG. 24

in a schematic cross section XXIV-XXIV the keyboard of FIG 23rd

The present electrical contacting device according to the invention is used e.g. from a basic structure, as shown in FIG. This basic structure is extremely compact and ensures high wear resistance and reliability. For the designated in FIG 1 as an anchor movable plate-shaped carrier there are according to the invention according to FIGS 2 to 22 very different configurations. The carrier 10 is provided with mutually insulated contact points 11, 21 such that they allow each other and / or the carrier 10 different potentials.

The carrier 10 is e.g. designed as a soft magnetic and electrically conductive metal plate on which a partial or full-surface electrical insulating layer 12 is applied. The insulating layer 12 can be realized by a paint application, film application, insulating surface treatment or equivalent. The insulating layer 12 is applied as needed to the top, the bottom or both sides. In this insulating layer 12, the conductive contact points 11, 21 and / or printed conductors 20 are applied, which allow each other and / or the carrier 10 different electrical potentials.

The carrier 10 shown in FIGS 2, 3, 4 has soft magnetic properties, is electrically conductive and designed on its upper side with two contact points 11, which serve as contact bridges for Öffnerkontakte. The two contact points 11 are mechanically decoupled from each other as shown in FIG 2 by an intermediate decoupling slot 13 for tolerance compensation, so that despite unavoidable manufacturing tolerances when actuated a good contact bearing is ensured on the opposite fixed contacts. The one contact point 11 on the one side of the decoupling slot 13 is through the electrically conductive Carrier 10 formed itself. The contact point 11 on the other side of the decoupling slot 13 is applied to the insulating layer 12 on the carrier 10. This is illustrated by the corresponding sectional images in FIGS. 3 and 4.

For actuation, the carrier 10 has a raised pressure area 14. In addition, the carrier 10 is provided at its first by a magnetic layer 16 (see FIG 5) breaking away area with an abutment 15 to which then the carrier 10 is pivoted upon further actuation. For a uniform distribution of the contact forces, the two contact points 11 are placed such that they form an isosceles triangle with the anvil 15. The pressure area 14 for mechanical actuation is in the vicinity of the anvil 15 in the interior of the triangle. Due to the arrangement of the two contact points 11 at the outer end of the carrier 10 and in that all four contact points of the contact points 11 are in alignment, an almost simultaneous jump behavior of the contact points 11 is realized. Preferably, the two contact points of each contact point 11 are as close together as possible.

FIGS. 5, 6, 7 show the various switching phases of the carrier 10 with the contact points formed as NC contacts 11 in the basic structure of the electrical contacting device according to the invention with a magnetic layer 16, a bottom support 17 and an intermediate spacer layer 18. FIG. 5 shows the carrier 10 shown in its rest position in which it is attracted by the magnetic layer 16 and its contact points contact 11 fixed contacts, not shown here. In the first phase of the switching operation, the side of the carrier 10 with the abutment 15 is pressed onto a bottom support 17. In the subsequent second phase, the contact points 11 are lifted on the other side of the fixed contacts and jump in the direction of the opposite bottom support 17th

In FIG 8, 9, 10, an embodiment of the carrier 10 is shown with two formed as normally open contacts 11 contact points, which are arranged in contrast to the embodiment shown in FIG 2, 3, 4 on the same side as the anvil. Otherwise, the structure corresponds to that of the previously described in detail carrier 10 with the Öffnerkontäkten 11 as shown in FIG 2, 3, 4. The switching phases in a provided with the carrier 10 with NO contacts 11 switch are shown in Figures 11, 12, 13. In the rest position, the carrier 10 is held on a magnetic layer 16 via its upper side. This is spaced by the spacer layer 18 the bottom support 17, which is provided with a substrate with fixed contacts. After the carrier 10 is broken away from the magnetic layer 16 after actuation on the side of the anvil 15 in the first switching phase of FIG 12, the carrier 10 in the second switching phase shown in FIG 13 jumps around the abutment 15 to the contact points 11 at the bottom of the Carrier 10 contact the fixed contacts. The arrangement of the contact points 11 is basically the same as in the NC contacts. However, the normally open contact points 11 are preferably not arranged at the outermost end of the carrier 10, but somewhat further inwards. This causes more favorable contact forces and a better contact opening behavior.

14, 15 show an embodiment of the carrier 10 with a break contact at the top and a make contact 11 at the bottom, in which case the break contact 11 is again insulated by an insulating layer 12 with respect to the carrier 10 and the normally open contact 11 formed by the latter. In principle, this function can also be achieved in the reverse manner, ie, by the NC contact 11 is realized by the carrier 10 itself and the NO contact 11 is applied to the insulating layer 12. If only one normally closed contact 11 plus one normally open contact 11 is realized, the two contact points of the opener form the top one described triangle, as well as the contact points of the shutter with the anvil 15 form a slightly smaller isosceles triangle. In this case, therefore, each of the contact points belonging to a contact are the vertices of the isosceles triangle described above.

With two closers or two openers is divided by a suitable slotting in independently resilient elements for a height tolerance compensation of the closely adjacent contact points of each contact point of the contact bridge carrier.

16, 17, 18, the switching phases are shown in a switch with such a carrier 10, which correspond in principle to those of the embodiments described above and therefore need no further explanation at this point.

With the above-described processing of the carrier 10 is obtained in addition to the contact functions, a circuit substrate that can accommodate electronic components in SMD design, chip design or key press. The power supply or electrical coupling of the electronic circuit is realized via raised contact points. A meaningful expression of such a circuit is shown in FIG 19, 20, where the actuating surface of the contact module is illuminated with a light emitting diode. Equally useful may be the integration of an electronic touch sensor, which detects the touch of the button regardless of the electrical contacts.

FIGS. 19, 20 show an embodiment of a carrier 10 which carries a circuit, eg in multi-layer design (multi-layer technology). The carrier 10 has on its top and bottom an insulating layer 12. On the upper-side insulating layer 12, an electrical circuit is applied as shown in FIG 19. In the present example, this comprises a contact point designed as a contact bridge 11, electrical components 19, for example, a bonded chip and a resistance pressure, contact points 21 for the electrical supply of the components 19 and these connecting tracks 20th

On the lower-side insulating layer 12 contact points 21 are also applied to the electrical supply, which are electrically conductively connected to the corresponding upper-side contact points 21 via a through hole according to FIG 22. In this case, the electrical connection line for through-connection on an insulating layer in the opening 22 is used up.

21 shows a cross-sectional view of the carrier 10 according to FIGS. 19, 20 with its top side and bottom side insulating layers and components 19 and / or contact points 11, 21 applied thereon.

The button described in conjunction with FIGS. 2 to 22 is alternatively used as a single command transmitter or as part of a membrane keyboard 30 shown in plan view in FIG. The membrane keyboard 30 includes a plurality of keypads 31, which are provided for non-safety-related switching processes. These keypads 31 are, for example, number or letter keypads 31a and an associated confirmation keypad 31b. Furthermore, the membrane keypad 30 comprises two keypads 32 provided for safety-related switching processes. These keypads 32 are used, for example, to control an electronic device, e.g. as a start or stop button.

The membrane keyboard 30 shown in FIG. 24 in a cross-section, which is to be understood as a diagram and in particular not true to scale, is constructed on the floor supports 17 common to all keypads 31, 32. At the visible in the mounted state for a user outside the membrane keyboard 30 is covered by a user interface forming the front sheet 33. The bottom support 17 and the Front sheet 33 are substantially planar and arranged approximately parallel to each other. The spacing layer 18 provided with openings 7 in the area of the key fields 31, 32 completely fills the space formed between the bottom support 17 and the front foil 33 in the area of the key fields 31. In the area of the keypads 32, the spacer layer 18 and the front foil 33 have the magnetic layer 16 interposed therebetween. The bottom support 17 is preferably realized by a conventional printed circuit board and carries in the field of keypads 31 arranged fixed contacts 34. Other fixed contacts not shown in detail are provided in the field of keypads 32 on the bottom support 17.

To implement the keypads 32 assigned to safety-related switching processes, the electrical contacting device described in detail in connection with FIGS. 2 to 22 is used. Depending on a carrier 10 is placed in the respective arranged in the region of each keypad 32 opening 7 of the spacer layer 18 in the manner described above and lies with its printing area 14 against the inner surface 35 of the front sheet 33 at. The front foil 33 is convexly curved in the area of the keypad 32. By pressing on the flexible front foil 33 in the region of the keypad 32, the carrier 10 is moved in the manner described for actuating the contact device.

For the switching processes to be triggered with the keypads 31, no special safety precautions are required. The associated buttons 36 are therefore preferably designed in a simple and therefore inexpensive technology. The key 36a assigned to the keypad 36a is executed like a bubble. For this purpose, the front sheet 33 is provided in the region of the keypad 31a with an embossed, with respect to the bottom support 17 convex dome top and carries on its inner surface 35 a corresponding fixed contacts 34 at a distance opposite electrically conductive contact surface 37. By pressure on the front film 33rd in the area of the keypad 31a, it is deformed from its convex rest position into a plane of actuation or concave in relation to the bottom support 17. As a result, the contact surface 37 is pressed against the fixed contacts 34, and triggered by the bridging the switching process. When canceling the actuation pressure, the front sheet 33 goes back to its convex rest position, whereby the switching contact is opened again.

For commonly used keypads without safety-related function, such as the confirmation keypad 31b, a button 36b provided with a disc-like snap element 38 is preferably used. The snap element 38 is arranged at a distance from the bottom support 17 approximately parallel to this and is preferably directly on the inner surface 35 of the front sheet 33 at. The snap element 38 is convexly curved in its rest position with respect to the bottom support 17, so that the keypad 31b, like the keypad 31a, is raised out of the plane of the user surface. The snap element 38 carries a bottom support 17 and thus the corresponding fixed contacts 34 facing contact surface 37. Under pressure on the key surface 31b, the snap element 38 changes abruptly its shape from the convex rest position in a relative to the bottom support 17 plane or concave operating position. In this case, in turn, the contact surface 37 is pressed against the fixed contacts 34 and the keypad 31b associated switching contact closed. When the actuating pressure decreases, the snap element 38 springs back into the starting position, whereupon the electrical contact is interrupted.

The advantages associated with the membrane keyboard 30 described in FIGS. 23 and 24 are, in particular, that the membrane keyboard 30 can be produced inexpensively by using the comparatively simple buttons 36. Since the contacting device described in FIGS. 2 to 22 is used for all safety-relevant switching processes, the membrane keyboard 30 can also be used for such purposes For which the use of conventional membrane keyboards due to high security requirements was not or only partially possible. This is particularly advantageous because the membrane keyboard 30 is constructed extremely flat and compact compared to conventional safety-related commanders. A major advantage is also that all keypads 31, 32 are contacted via the floor support 17 designed as a printed circuit board and thus eliminates difficult to automate wiring of the button. Of great advantage is further that all keypads 31, 32 are covered by a common, substantially flat front sheet 33. Thus, in addition to a simple mountability and the possibility of a uniform design especially high dirt resistance of the membrane keyboard 30 is achieved, which in turn has a positive effect on their reliability.

Claims (15)

1. Electrical contacting device with

   a movable, essentially plate-shaped carrier (10) with electrical contact positions(11, 21), which are isolated from each other such that they make possible different potentials to each other or to the carrier (10), and with

   fixed contacts lying opposite the electrical contact positions (11, 21) and contacting the latter after a switching movement of the carrier (10),

   characterized in that

   - the plate-shaped carrier (10) has an opposing support (15) in an area which breaks away first from the magnetic layer (16) in a switching movement,

   - the plate-shaped carrier (10) is constructed so that the electrical contact positions (11, 21) which are arranged on the outer end of the support (10) for a side lying opposite the opposing support (15) and the opposing support (15) form one corner point of a triangle, and

   - the plate-shaped carrier (10) for mechanical actuation features a pressure area (14) which lies within the triangle in the vicinity of the opposing support (15).
2. Electrical contacting device in accordance with claim 1, characterized in that, the triangle formed by the electrical contact positions (21, 15) and the opposing support (15) is equilateral.
3. Electrical contacting device in accordance with claim 1 or 2, characterized in that, the carrier (10), in addition to contact positions (11, 21), also features conductor tracks (20).
4. Electrical contacting device in accordance with one of the previous claims, characterized in that, at least one of the contact positions (11) is embodied as a contact bridge.
5. Electrical contacting device in accordance with one of the previous claims, characterized in that the carrier (10) is embodied with at least one partial insulating layer (12).
6. Electrical contacting device in accordance with one of the previous claims, characterized in that the carrier is designed as an integrated circuit (10).
7. Electrical contacting device in accordance with one of the previous claims, characterized in that the carrier (10) has soft-magnetic properties and is held in the rest position by magnetic force.
8. Electrical contacting device in accordance with one of the previous claims, characterized in that the contact positions (11. 21) and/or conductor tracks isolated from one another by at least one of the isolation layers (12) are connected selectively to one another.
9. Electrical contacting device in accordance with one of the previous claims, characterized in that the carrier (10) features at least one break-through (21) which is used for contacting between contact positions (11, 21) and/or conductor tracks (20) in different planes.
10. Electrical contacting device in accordance with one of the previous claims, characterized in that the carrier (10) is an electrically-conductive foil and assumes the function of a contact bridge.
11. Electrical contacting device in accordance with one of the previous claims, characterized in that the carrier (10) features at least two contact bridges (11) isolated from each other.
12. Electrical contacting device in accordance with one of the previous claims, characterized in that a decoupling slit (13) is provided between the contact positions (11).
13. Keyboard (30) with at least a first keypad (32), to which an electrical contacting device in accordance with one of the previous claims is assigned, and at least a second keypad (31) of which the assigned keys (36) are embodied as switching domes or features a spring switch behavior transmitted by a snap element (38).
14. Keyboard (30) in accordance with claim 13, characterized by an essentially flat front membrane (33) covering all keypads (31, 32) together.
15. Keyboard in accordance with one of the claims 13 or 14, characterized by a common circuit board (17), on which both the electrical contacting device assigned to the keypad or to a first keypad (32) and also the keys (36) assigned to the keypad or to each second keypad are contacted.

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