Guide to membrane switch backlighting

EL lamps

EL stands for “electrical luminescence.” Solid-state electroluminescent lamps produce light by charging an AC/DC current into phosphorus. They’re an excellent option for membrane switch backlighting because of their even look.

When applied to membrane switch assemblies, EL lamps are usually implemented as a panel just underneath the graphic overlay. Note that they require an alternating current source so they might not be the right pick for all potential applications. If your device already features an inverter in its design, an EL lamp can offer a great backlighting option.

Pros of the EL lamps:

• They’re very thin,
• They have low heat throw
• They present an even visual look.

Cons of EL lamps:

• The one key disadvantage of EL lamps is that they require a power inverter.

Fiber optics

If you decide to shine an LED through optical fibers, you can illuminate specific parts of your membrane switch. This type of precision can come in handy if you’re looking to illuminate one part of the switch and leave the other ones dark.

And the best part is that this solution also comes at a low cost. Fiber optics have low temperatures, which is another critical advantage of this technology. That’s why fiber optics are a common backlighting technique among many membrane switch applications.

Still, you might be dealing with a large pigtail depending on how many fibers you bring together at an LED. This is a physical limitation that can be addressed by specifying woven fiber-optic pads. As you can imagine, this solution can be pretty expensive. But it brings you compact, low-powered, and highly controlled backlighting.

Pros of fiber optics:

• Low power requirements,
• Low temperature,
• Gorgeous light quality,
• Flexible and even light appearance.

Cons of fiber optics:

• Potentially large or bulky pigtail,
• Potentially higher cost.

LGL

LGL stands for Light Guide Layer. This technique uses light-diffusing plastic that helps to light all the broad areas using LED sources evenly. It’s important to mention that LGL comes at a lower cost than woven fiber-optic pads. But to achieve the same effect, you will have to use more LEDs.

That’s why LGL is a good choice for high-volume and low-cost applications – even if it requires more components. In this scenario, manufacturing automation can become a critical factor when implementing the technology because it keeps production costs low.

Pros of LGL:

• Cheaper than fiber optics,
• Compact design,
• Even look.

Cons of LGL:

• It requires more LEDs,
• It needs surface printing of black-out areas in order to direct light appropriately.

Get high-quality membrane switches at Melrose

We have years of experience in providing companies with high-quality membrane switches that offer suitable backlighting options, keeping the cost low, and ensuring excellent performance.

Get in touch with us to talk to our consultants and receive expert advice on creating the best possible membrane switch design.