Backlighting is used to illuminate certain types of electronic membrane switches. Generally speaking, there are three primary types of backlighting options used in this application: light-emitting diode (LED), fiber optics, and electroluminescent (EL) lamps. LEDs have long been the de-facto standard, consisting of an array of light-emitting diode bulbs that illuminate the display interface. The problem with LEDs, however, is that they fail to provide even lighting, meaning some areas may appear brighter than others. Fiber optics offers a more consistent form of backlighting for membrane switches. And best of all, fiber optics are not affected by extreme fluctuations in temperature or humidity, making them an excellent choice for membrane switches used in outdoor applications.
But the newest method of backlighting in membrane switches is electroluminescent (EL) lamps. When compared to LEDs and fiber optics, EL typically costs the least amount of money. This makes it an ideal choice for budget-conscious individuals and companies in need of backlighting options for membrane switches. Of course, there are other reasons to choose EL for backlighting, as well. Boasting a half life of roughly 3,000 to 8,000 hours (varies depending on the type/quality of phosphor), they last long while consuming a minimal amount of energy.
There are some caveats to using EL backlighting, however, including its susceptibility to fading after it reaches its half life. After 3,000 to 8,000 hours, its brightness will begin to fade. This doesn’t necessarily mean that EL backlights will stop working, but rather than will become dimmer after they reach their half life. This makes EL backlights a suitable choice for applications in which the lamp is not left on for long periods of time. As long as the EL lamp is turned off, it can offer several years of use without having to be replaced. And when it does need to be replaced, the minimal cost of new EL lamps shouldn’t cause any major financial hardship for businesses.
Of course, backlighting is only one of the many considerations that should be made when choosing a membrane switch. You should also consider the switch’s size, weight, responsiveness, effectiveness in its intended application, and its overall ergonomics. Hopefully, this will give you a better understanding of EL lamps and their use in membrane switches.