EP0395779A1 - Contact unit - Google Patents

Abstract

Contact units with snap discs not only have a very long service life but also have virtually constant contact properties over the complete service life. However, in previous designs, it was only possible to switch on using such contact units. The design provides a contact arm (6) which is connected to the snap disc (1) and which also allows changeover switching, on operation of the contact unit, at the same time as switching on. <IMAGE>

Description

The invention relates to a contact module, formed from a contact plate, on which contacts lying on one level are attached, and a counter contact arranged on the contact plate and resiliently pressable onto the contacts, consisting of a snap disk provided with at least one contact, the edge of which is direct or rests on the contact plate via the arms provided there.

Such contact modules are widely used today as precision contacts in both individual switches and keyboards. The particular advantage of these contact modules is, in particular, the constant suspension and contact properties over their entire service life in combination with high Lifespan. Decisive for this are the snap disks used in these contact modules, also called snap springs or monostable snap elements, which ensure through their characteristic curve that a predetermined contact pressure is maintained over the entire service life both in the preloaded rest position and in the depressed position and the contacts are always fast closed and opened, so creeping contact is prevented. Therefore, such contact modules are particularly recommended for use in electronic devices, the contact plate of these contact modules can be directly the base plate provided with conductor tracks, for example a keyboard, on which the mating contacts, consisting of these snap disks provided with contacts, can then be placed. With contact modules constructed in this way, more than 10⁷ switching cycles can be achieved.

A disadvantage of these contact modules is that, owing to the snap disks used, they can only be used to implement an "on" button. Contact modules of this type serving as changeover switches have not yet been disclosed.

The object of the invention is therefore to design contact modules of the type described while maintaining the previous advantages so that they can also be used as changeover switches. This is achieved in the manner according to the invention in that at least one contact arm, which is provided with at least one contact and which extends from the center, from the edge or from arms of the snap disc, is connected to the snap disc.

The invention thus takes advantage of the fact that the snap disc deforms when pressed so that it forms a wavy line in cross section. This undulating course means that the angle at which the area lies at the center as well as that at the edge to the contact plate is reduced or even becomes negative. This change in angle is now used by the invention to provide a contact arm in these areas, which can now be used as a changeover contact for contacts also attached to the contact plate. Thus, when the contact module is actuated, both the "on" contact is closed and the contact on the contact arm is opened. If the contact arm is provided on the edge region of the snap disk, the contact surface of the edge of the snap disk or that of the extension arm serves as an abutment for the rocking movement of the edge region of the snap disk or the contact arm. If the contact module is actuated or the snap disk is depressed, the angle between the edge region and the plane of the contact plate decreases on this side, while the contact arm lifts off the contact plate on the other side. The lifting of the contact arm from the contact plate or the separation of this contact arm can of course also be used to ensure that the contact arm comes to rest on an overlying contact. In any case, it is possible with the contact module according to the invention to switch on and switch over while maintaining the advantages that these snap disks offer.

The contact arm will usually come off radially from the snap disk. Depending on the individual conditions, it can, however, be radial to tangential from away from the snap disc, which in the latter case results in an evaluable rotary movement of the contact arm.

• Fig. 1 die Unteransicht einer derartigen Schnapp scheibe,
• Fig. 2 die mit Kontakten bestückte Schnappscheibe im Querschnitt nach der Schnittlinie II/II der Fig. 1, vorgespannt,
• Fig. 3 in gleicher Darstellung wie Fig. 2 die Schnappscheibe betätigt,
• Fig. 4 und
• Fig. 5 Detailansichten von den Fig. 2 und 3,
• Fig. 6 und
• Fig. 7 Darstellungen wie die Fig. 2 und 3, jedoch jeweils mit einem obenliegenden Kontakt,
• Fig. 8 eine Schnappscheibe mit einem vom Zentrum ausgehenden Kontaktarm und
• Fig. 9 und
• Fig. 10 eine schematische Darstellungsweise der Schnappscheibe nach Fig. 8.

An exemplary embodiment of the subject matter of the invention is shown schematically in the drawing, namely:

• 1 is the bottom view of such a snap disc,
• 2 the snap disk equipped with contacts in cross section according to section line II / II of FIG. 1, prestressed,
• 3 in the same representation as FIG. 2 actuates the snap disk,
• Fig. 4 and
• 5 detailed views of FIGS. 2 and 3,
• Fig. 6 and
• 7 representations like FIGS. 2 and 3, but each with an overhead contact,
• Fig. 8 is a snap disc with a contact arm extending from the center and
• Fig. 9 and
• 10 is a schematic representation of the snap disk according to FIG. 8.

Booms (2, 3, 4, 5) are located on a snap disk (1) (the actual snap disk is shown in dash-dot lines), the boom (5) being connected to a contact arm (6). An "on" contact (7) is provided centrally in the snap disk (1). Another contact (8) is located at the end of the contact arm (6). The arms (2, 3, 4, 5) are provided with expressions (9, 10, 11, 12). With these expressions (9, 10, 11, 12), which, however, can also be attached contacts, the snap disk (1) lies on conductor tracks (13, 14, 15, 16) are on a contact plate (17) (dash-dotted lines). Fig. 2 shows the pretensioned state, in which the snap disc (1) is already pretensioned so that the expressions (12, 10) are on the conductor tracks (14, 16), together with the contact (8) on the conductor track (13) rests. The contact (7) is still removed from the conductor track (15). When an actuating force acts, represented by the arrow (18), the snap disc (1) deforms, as shown in FIG. 3, so that the contact (7) located centrally on the snap disc (1) suddenly abuts the conductor track (15) hangs up. At the same time, the contact (8), which previously rested on the conductor track (13), is lifted off this conductor track (13), the conductor track (14) serving as an abutment for this rocking movement.

The detailed representations of FIGS. 4 and 5 are intended to illustrate this again. Shown here is the conductor track (14) with the expression (12) resting on this conductor track (14). 2, the edge region of the snap disk (1) forms a certain angle (19) with the plane of the contact plate (17). The contact arm (6) is approximately parallel to the plane of the contact plate (17). In the pressed position, the angle between the edge region of the snap disc (1) and the plane of the contact plate (17) decreases, as indicated by the arrows 20. At the same time, the contact arm (6), as indicated by the arrows 21, lifts off the contact plate (17).

It should be noted that this switching process always takes place suddenly, so that creeping contact or contact deletion is avoided.

6 and 7 again show a snap disk equipped with contacts (7, 8), on the one hand in the rest position (FIG. 6) and on the other hand in the actuated position (FIG. 7). The contact (28) is also here in the rest position on the conductor track (13). In the pressed state (Fig. 7), however, this contact (28) strikes an overlying mating contact (22), so that there is a connection from the conductor track (15) via the contact (7) to this mating contact (22).

The snap disk (23) according to FIG. 8 essentially follows the same principle, since here the wave-shaped deformation of the snap disk (23) is used to form a changeover contact. The center contact (7) is also here above the conductor track (15) (FIG. 9), so that it is pressed onto the conductor track (15) when the actuating force (18) acts. In this embodiment, however, a contact arm (24) is separated from the snap disk (23) and rests with its contact (25) in the rest position (FIG. 9) on a conductor track (26) lying in the plane of the contact plate (17). In the pressed state, however, this contact arm (24) with its contact (25) is suddenly lifted off the conductor track (26), so that the same effect as with the snap disk (1) according to FIGS. 1 to 3 results.

Claims (3)

1. Contact module, formed from a contact plate, on which contacts lying on one level are attached, and an arranged on the contact plate, resiliently pressable onto the contacts, consisting of a snap disk provided with at least one contact, with its edge directly or via the arm provided there rests on the contact plate,
characterized,
that at least one contact arm (6) provided with at least one contact (8) is connected to the snap disc (1) and extends from the center (at contact 7) from the edge or the arms (2, 3, 4, 5) of the snap disc (1 ) goes out. 2. Contact module according to claim 1,
characterized,
that the contact arm (6) points radially to tangentially from the snap disc (1). 3. Contact module according to one of claims 1 or 2,
characterized,
that the contact (8) of the contact arm (6) in the pretensioned state (Fig. 2) of the snap disk (1) on another, on the contact plate (17) attached contact (conductor 14) or in the pressed state (Fig. 3) Snap disc (1) abuts a contact arranged above it.

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