Membrane switches have become a popular electrical switching solution. Like mechanical switches, they are designed to control an electrical circuit. When the membrane switch is open, the circuit is incomplete. When the membrane switch is closed, the circuit is complete. Membrane switches are unique, however, because they feature a flexible — typically elastic or semi-elastic — contact. As a result, they support several different backlighting solutions, some of which are listed below.
It’s not uncommon for membrane switches to use light-emitting diode (LED) backlighting. The LED bulbs are typically mounted to the surface or embedded into the circuit layer, though they can also be installed on a separate layer. Once in place, the LED bulbs illuminate the membrane switch from underneath, allowing for a higher level of visibility and ease of use in otherwise dimly lit environments. LED backlighting is a popular choice because of its energy-efficient properties. However, there are several other backlighting solutions supported by membrane switches.
Some membrane switches use optical fiber backlighting. Optical fiber consists of long and thin strands of glass. The glass is able to propagate light as the light travels through it, thereby illuminating the membrane switch.
Like LED, optical fiber backlighting is highly energy efficient. Furthermore, it’s able to withstand extreme environments, including dry environments with 0% relative humidity as well as wet environments with 100% humidity. It’s important to note that optical fiber backlighting is often used in conjunction with LED backlighting.
A third type of backlighting supported by membrane switches is electroluminescent (EL). EL backlighting doesn’t offer the same energy-efficient properties as LED or optical fiber backlighting. With that said, it costs less than these other backlighting solutions, making it a popular choice for budget-conscious business owners and consumers.
EL backlighting can be configured to project light in specific colors. If a particular color of light is desired, the EL bulbs are fitted with the appropriate phosphor compounds. Different phosphor compounds produce different colors of light. As a result, manufacturers can create membrane switches with a specific color of backlighting by using the right type of phosphor compounds in the EL bulbs.
Membrane switches are often preferred over mechanical switches because of their low-profile design and natural resistance to dust, dirt and debris. While there are dozens of types of membrane switches on the market, most feature one of three types of backlighting: LED, optical fiber or EL.