There are various possibilities for the realisation of illuminated keyboards, which are used in particular for industrial or medical applications.
Under the generic term LumiLine^©, we develop, manufacture and distribute foil-covered operating, input and display solutions designed individually for your application.
In the following, we would like to present some of them:

1.) LumiLine^©-KuHu: “illuminated short stroke keyboards:”

This kind of illumination from behind has proven of worth in many different fields of application for many years and is time-tested. Apart from the range of colours for the surface illumination in green, yellow, red or white, the possibility of a spot-/status display is also given. Moreover it is a great advantage that a surface illumination of the key area is possible as well.

Customised keyboard

• with illuminated short stroke keys
• blue 7-segment-display

Input system ES46034.0001-a, customised version
with support plate, printed circuit board, display snap dome, front foil ...

more information ==>

2. ) LumiLine^©-LED:  “surface illumination by means of snap domes”

Here you can see some examples for LumiLine©-LED.
This solution has the advantage that it is flat, extremely robust and longlasting, as LED's are used. Despite the snap dome technology, a surface illumination of the keys is possible! 
The very good cost-performance ratio tells its own tale.  
Feel free to inquire!

3.) LumiLine^©-EL: “illumination from behind by means of EL-foils
(electro-luminescence)”

This very flat surface illumination from behind by means of a cold light source has  the disadvantage that a trigger in the form of an EL-invertor is required and the  durability is limited against this trigger.
See also: www.foiltronic.de/html/foiltronicr_el.html

4.) LumiLine^©-TP: “the support plate serves as light guide at the same time.”

5.) LumiLine^©-Flex: “illumination from behind by means of flexible light guides.”

See also: www.foiltronic.de/html/foitronicr_wl.html
This relatively expensive solution has the advantage that it is flat, extremely robust and longlasting, furthermore, a surface illumination of the keys is possible.

You can find more excamples at:
www.folientastaturen.woehrgmbh.de/html/nachtdesign.html