Membrane switches are found just about everywhere. Characterized by conductive screen, usually featuring ink such as copper, silver or graphite, it differs from its mechanical switch counterpart in the sense that it conducts electricity. You can find membrane switches in microwave ovens, household appliances, air conditioners, TV remotes, human machine interfaces and more.
In order for a membrane switch to function as intended, however, it must feature some type of backlight. The purpose of a backlight, as the name suggests, is to illuminate the back of the switch, allowing the operator to see it more easily. There are several different types of membrane switch backlights, each of which has its own specific purpose. To learn more about the different backlights and which one is best suited for membrane switches, keep reading.
There are generally three different backlights used in membrane switches: light-emitting diodes (LEDs), optical fiber and electroluminescent. LEDs are energy-efficient, easy to use and readily available, making them the preferred choice among many professionals. With that said, however, LEDs are susceptible to bright spots, as some areas of the membrane switch may feature bright colors than other areas. On the plus side, however, LEDs can either be mounted to the surface of the membrane switch or applied to a separate layer.
Optical fiber is another popular choice of backlighting used in membrane switches. It features two or more layers of fiber optics that create a light-emitting area. The fibers are bundled at the end to create a circular ferrule, at which point they are attached to an LED. Some optical fiber backlights can last for up to 100,000 hours, at which point they must be replaced. Optical fibers are also resistant to moisture, humidity and extreme temperature changes, making them an excellent choice for outdoor applications.
The third type of backlighting used in membrane switches is electroluminescent. EL backlights cost less than their LED and optical fiber counterpart, often featuring colors like blue, green and yellow. You can expect an EL backlight to last for roughly 5,000 to 7,000 hours, depending on the type of phosphor used. Assuming the backlight doesn’t remain on for long periods at a time, EL backlights are a viable solution for membrane switches.
So, what’s the best type of backlight to use for a membrane switch? As you can see, there are advantages and disadvantages associated with each. Familiarize yourself with the different types and choose the one that’s right for your specific needs.