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How’s This for a Bright Idea? Backlighting for Membrane Switches

Backlit Membrane Switch

As we get closer to the end of the year, we are beginning to see holiday lights being put on display. While the glow and colors are meant to put us in a festive mood, we can’t help but think about a different type of illumination that’s near and dear to our hearts – backlighting for membrane switches.

For the average person, a small blinking light or a bright control panel may not mean much, but for a product designer, backlighting can make a dramatic difference in the appearance and functionality of a user interface.

What is backlighting?

Backlighting involves adding components to a membrane switch that illuminate the front surface of the user interface. This light can be concentrated in a specific area when activated, or the entire display area whenever the device is in use.

Backlighting is not required for membrane switches, but the feature does add several useful benefits to the end product, including:

  • Improving visibility for the user when the product is operated in a dark or dimly lit environment
  • Making inputs and keys easier to find and read
  • Drawing attention to a certain area, such as indicator lights on a control panel
  • Enhancing appearances with a modern feel
  • Making products more accessible for consumers with disabilities

Types of Backlighting for Membrane Switches

There are four main methods for incorporating backlighting into a membrane switch – each with unique advantages and disadvantages.

Light-Emitting Diodes (LED)

As the most common and economical backlighting technology, LEDs are ideal for illuminating specific areas (such as keys or indicator lights) but are not as conducive for full displays.

LED attributes include:

  • Low power consumption and heat output
  • Long service life – usually over 100,000 hours
  • Surface-mounted
  • Can be single- or multi-colored

Fiber Optic Backlighting

Fiber optic backlighting is constructed from a thin layer of fiber optic cloth that is inserted between the graphic overlay and circuit layer. The cloth is bundled into a circular ferrule and coupled to an LED light source. Fiber optic backlighting is ideal for consistent lighting across large areas.

Other fiber optic features include:

  • Creates low heat and no electromagnetic interference
  • Lower power requirements
  • Durable and easy replacement of the LED light source
  • Can handle extreme temperatures and humidity
  • Moderate-level cost

Electroluminescence Backlighting

Electroluminescence (EL) backlighting features printed ink with light-emitting phosphors. A thin layer with this ink is applied between the graphic overlay and the circuit. EL is a great choice when you need uniform backlighting across an entire surface.

More characteristic of EL:

  • Typically more expensive than LED and fiber optics
  • Exceptional design flexibility and customization
  • A good option for membrane switches with tactile feedback
  • Limited colors options
  • Requires a DC-to-AC inverter

Light Guide Film

Last but not least, Light Guide Film (LGF) is comprised of a thin sheet of specialty plastic with side firing LED’s that is typically placed between the graphic overlay and circuit. This approach provides brighter, more uniformed backlighting than LEDs alone.

A few things to keep in mind about LGF:

  • Can be implemented in small and large areas
  • Extremely thin – a good option for very compact designs
  • Poor design could lead to light leakage or hot spots
  • Single color
  • Often more expensive than other backlighting options

Custom Converting for Backlit Membrane Switches

Since membrane switches can be customized to your application, the possibilities really are limitless for backlighting. For example, multiple backlighting methods can be integrated to create a truly unique and effective user interface. However, the addition of backlighting does increase the complexity of a membrane switch design, so it’s important to have a manufacturing partner with experience in these compact components.

At Tapecon, we’ve helped design, test, and produce high-quality membrane switches for a wide array of industries. With our materials expertise and range of printing and custom converting capabilities, we can add a host of unique features, including (but not limited to) backlighting technology.

Get started with membrane switches.

At Tapecon, we have over 100 years of experience helping customers solve their complex product challenges. Learn more about our membrane switch applications.

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