Membrane switches are found in everything from microwave ovens and air conditioners to TV remote controls and human machine interfaces (HMIs). They are characterized by the use of a circuit printed on PET or ITO, whereas a traditional mechanical switch consists of copper and plastic parts. The actual ink printed on a membrane switch is typically either copper, silver or graphite, allowing for the flow of electricity (these metals are conductive)>
But membrane keypads require some type of backlight in order to function. The backlight works by illuminating the keys; thus, allowing the operator to clearly see the keypad.
Of course, there are several different types of backlights used in membrane switches, each of which has its own unique characteristics. With that said, most of these backlights consist of either electroluminescent (EL) lamps, light-emitting diode (LED) or fiber optics. Today, we’re going to take a closer look at EL backlights for membrane switches, revealing their advantages and disadvantages.
One of the main benefits of choosing an EL backlight is the cost. When compared to fiber optics and LED, they generally cost less, making them an excellent choice for budget-conscious consumers. This is particularly beneficial if you need to order a bulk quantity of membrane switches, as it can yield significant cost-savings benefits. But this is just one of the many reasons why so many consumers prefer EL backlights for their membrane switches.
Another benefit of EL backlights for membrane switches is their longevity. All backlights will eventually burn out, requiring the operator to replace the bulb. With EL backlights, however, you’ll reap the benefits of longer-lasting illumination. It’s not uncommon for EL lamps to burn for 16,000 or more hours, which is more than enough for typical usage. Granted, that still falls short of LED backlights, which burn for up to 100,000 hours, but it’s still pretty impressive.
On the other hand, EL backlights suffer from faded brightness upon reaching their half life. In other words, the backlight will become dimmer and dimmer after it reaches half of its life expectancy (around 3,000 to 8,000 hours). When this occurs, the EL backlight will still work, but you can expect a dimmer illumination that’s not as bright as before. In any case, this is a fairly small issue considering that EL backlights are so cheap and easy to replace. If and when you notice the EL bulb becoming dim, simply replace it with a new one for instant brightness.