Background Lighting

Membrane switch keyboards with background lighting

Background lighting in membrane switch keyboards can be a complex solution - but it does not have to be equally expensive. Electronics works primarily with the following three types of background lighting:

Electroluminescent lamps - electric lamps

Electric lamps consist of foils with partial, serigraphically imprinted phosphorus. This lights up when energized. The technology is used e.g. when complicated geometric designs need to be visible even in dimmed lighting, and when a minimal membrane switch keyboard thickness is required (1-3 mm).

LED background lighting

Background lighting via LEDs in membrane switch keyboards requires a greater height in the keyboard itself than normally is necessary for electric lamps. The light from the LEDs needs a certain height in any material in order to be able to spread and provide a uniform lighting effect. Contrary to the electric lamp, the LEDs do not require high voltage, and they generally last longer (depending on the supply voltage).

Background lighting via PCB

If the membrane switch keyboard design allows for it, it can be mounted on a transparent glass or acrylic plate. This makes it possible for light from an underlying light source - e.g. mounted on the controller PCB - to shine through the keyboard. This design usually requires a cabinet height of more than 3 cm - and the technology can only be used for certain types of membrane switch keyboard. One of the advantages of this solution is that the choice of light source is not limited to the types of LED that can be integrated directly into the membrane switch keyboard.