Keypads support several backlighting technologies, one of the most common being electroluminescent (EL). If you’re planning to buy a keypad, you may want to choose EL backlighting. Like all backlighting technologies, it will illuminate the keys from behind. EL backlighting simply involves the use of a special type of lighting technology that distinguishes it from other backlighting technologies.
The Basics of EL Backlighting
EL backlighting is characterized by the use of an electroluminescent layer — hence the name. The term “electroluminescent” refers to any object or material that’s able to produce light as electricity travels through it. It’s not the same as incandescent. Incandescent involves the use of heat to produce light, whereas electroluminescent leverages electricity to produce light. EL backlighting consists of an electroluminescent layer that’s able to produce light as electricity travels through it.
How EL Backlighting Works for Keypads
In keypads, EL backlighting typically consists of a layer of phosphor compounds. Phosphor compounds are electroluminescent. As electricity travels through them, phosphor compounds will produce light.
Many keypads feature a layer of phosphor compounds that’s sandwiched between two conductive layers. The conductive layers are made of an electrically conductive material. During use, electricity will travel through the conductive layers as well as the phosphor compounds between them The phosphor compounds will then illuminate by producing light.
Why Keypads Use EL Backlighting
Not all keypads use EL backlighting. Nonetheless, EL has become one of the most popular backlighting technologies for keypads, membrane switches and other electronics.
When compared to other backlighting technologies, EL backlighting ranks as one of the most energy efficient. It consumes less energy than many other backlighting technologies. The low energy requirements make it a popular choice for keypads.
EL backlighting also produces little or no heat. Heat isn’t a concern with EL backlighting because it’s not an incandescent technology. EL is an electroluminescent technology, meaning it involves the use of electricity — not heat — to produce light.
EL backlighting can be used in conjunction with light guides. Light guides consist of foil pieces that are designed to distribute light. They don’t produce light themselves. Rather, light guides are only designed to distribute light. You can find keypads that feature both EL backlighting and light guides. The light guides will take the light produced by the EL layer, and they’ll distribute that light throughout the keys. With light guides, keypads experience even brightness.