DE29912656U1 - Keyboard for an input unit - Google Patents

Description

Keyboard for an input unit

The invention relates to a keyboard for an input unit, consisting of

a cover film,

a carrier material,

a carrier board and

Means for illuminating the keys.

Keyboards of the type mentioned above are already known from the state of the art; they are generally referred to as membrane keyboards.

To illuminate the keys, a luminescent foil can be used. This produces a cold glow below the usual glow temperature. This prevents damage to the membrane keyboard. The glow is achieved using radiation or high voltage, for example. When diodes are used, i.e. a separate diode for each key, these are each individually wired, which means that production is quite complex and therefore expensive.

The invention is based on the object of creating a keyboard of the type described above, which enables the keyboard to be illuminated using simple means and which can be produced inexpensively.

The solution of the problem by the invention is characterized in that

the keys (7) are designed as at least partially translucent and/or reflective domes. The desired lighting effect is thus achieved. The lettering (9) can be clearly recognized, particularly if, according to the further development, the domes are designed to be largely completely illuminated by the means (4) for illuminating the keys (7).

The means (4) for illuminating the keys (7) are advantageously connected to the carrier board (3). According to a further development, the means (4) for illuminating the keys (7) are attached to the side of the carrier board (3) which is opposite the side on which the keys (7) are attached. The means (4) for illuminating the keys (7) are preferably accommodated in a housing.

For example, to improve the feel of the keys (7), the domes can be made of transparent polyurethane.

To generate the required switching process, the carrier material (2) is equipped with contact springs (6) which, when pressed down, perform the electrical function of closers.

According to the further development, the carrier material (2) is translucent or is recessed in the area of the means (4) for illuminating the keys (7). This ensures that the light from the means (4) for illuminating the keys (7) can reach the dome.

An embodiment of the device according to the invention is shown in the drawings. The figure shows a schematic section through a button of the device.

The figure shows a partial section through a membrane keyboard with a cover film 1 and, for example, a key 7 that is designed as a dome. A foam film 5 is inserted between the carrier material 2 and the cover film 1, which is partially recessed in the area of the key 7, preferably round. All films, i.e. the cover film 1 with the keys 7, the carrier material 2 and the foam film 5 inserted between them, are attached to a carrier plate 3. The connection of the individual films to one another is preferably achieved by gluing.

The carrier material 2 with the applied conductor tracks is equipped with switches, so-called contact springs 6, which are attached exactly below each button 7. For the safe actuation of the switch, i.e. the contact spring 6, an auxiliary element 8 is inserted between the contact spring 6 and the button 7, preferably in the actuation direction X of the button 7.

The carrier board 3 is also provided with openings in the area of each key 7, under which means 4 for illuminating the keys 7 are mounted. These means 4 are connected directly to the carrier board 3, e.g. by soldering. Light-emitting diodes, for example, are provided as means 4 for illuminating the keys 7.

In this embodiment, the light can pass from the underside of the carrier board 3, i.e. from the diode 4, through the opening in the board 3, over the translucent carrier material 2 and the partially translucent cover film 1, to the dome of the key 7. The reflection of the dome ensures that the inscription 9 is visible through the translucent dome.

The invention makes it possible to produce a device of the type described above inexpensively and to achieve the desired lighting effect of the keys using simple means.

List of reference symbols:

1 cover foil

2 Carrier material

3 Carrier board

4 Means of illuminating the key

5 Foam foil

6 Contact spring

7 Button

8 Auxiliary element

9 Labeling

X Actuation direction

Claims (9)

1. Keyboard for an input unit consisting of
a cover film ( 1 ),
a carrier material ( 2 ),
a carrier board ( 3 ) and
Means ( 4 ) for illuminating the keys ( 7 ),
characterized in that
the buttons ( 7 ) are designed as at least partially translucent and/or reflective domes. 2. Device according to claim 1, characterized in that the domes are designed to be largely completely illuminated by the means ( 4 ) for illuminating the keys ( 7 ). 3. Device according to claim 1 or 2, characterized in that the means ( 4 ) for illuminating the keys ( 7 ) are connected to the carrier board ( 3 ). 4. Device according to claim 3, characterized in that the means ( 4 ) for illuminating the keys ( 7 ) are fastened on the side of the carrier board ( 3 ) opposite the keys ( 7 ), preferably in a housing. 5. Device according to claim 2, characterized in that the means ( 4 ) for illuminating the keys ( 7 ) are attached to the carrier material ( 2 ). 6. Device according to one or more of the preceding claims, characterized in that the domes are made of polyurethane. 7. Device according to one or more of the preceding claims, characterized in that the carrier material ( 2 ) is equipped with contact springs ( 6 ). 8. Device according to one or more of the preceding claims, characterized in that the carrier material ( 2 ) is translucent. 9. Device according to one or more of the preceding claims, characterized in that the carrier material ( 2 ) is recessed in the region of the means ( 4 ) for illuminating the keys ( 7 ).