The use of EL membranes in the field of membrane keypads offers designers many advantages. The benefits include low power consumption, low mechanical fitting height, and mechanical flexibility.
The homogeneous light distribution of the background lighting is a further advantage. The electro-luminescent phosphor particles are distributed evenly on the surfaces of the membranes. By contrast, light sources such as LEDs or bulbs are points of light.
EL membranes emit homogeneous light over the entire surface. Thanks to their high degree of efficiency, EL membranes are characterized by very low power consumption. Replacing bulbs or LEDs with EL membranes reduces power consumption by more than 50%.
Little energy is lost in the form of heat. Normally, EL membranes are less than 0.3 mm thick. This offers an advantage in comparison with sources of points of light, which require a 2 to 3 mm thick light guide in order to achieve a similarly homogeneous level of light distribution.
As the EL membrane is normally manufactured using the silk screen printing process, it is possible to produce almost any drawing or graphic as an EL membrane. The only restriction in terms of design is the flat shape of the membrane.
The surface can also be illuminated selectively. If required, any section of the membrane can be lit separately. The brightness or level of illumination of a membrane is the main factor which determines the operating conditions. EL membranes require an AC signal for operation. Increased membrane brightness is achieved by means of higher voltages or frequencies respectively. In order to determine the initial brightness, it is first necessary to establish the required lower level of both the brightness and the operating life.