Membrane Switch Lighting Options

Lighting is commonly used with membrane switches for feedback, enhanced usability and differentiation of critical switches. lighting may be powered by the switch circuitry or directly connected to the main power source.

Typical kinds of lighting

• LED's
• Optical fiber
• Electroluminescent lamps
• Phosphorescent inks

Membrane Switch LED Lighting

LED's are a simple way to add lighting to the membrane switch. They are soldered in place over the conductive ink traces and Integrated directly onto the circuit layer. LED's are normally used as indicators or to provide backlighting to keys and deadfronts. When used as backlighting, they require a diffusing layer to cut the intensity of the light and spread it over a larger area.

Benefits of LED lighting

• Ideal for selective lighting
• Intense brightness
• Available in variety of colors
  
• Economical and widely available

Membrane Switch Optical Fiber Lighting

Optical fiber lighting is achieved by means of glass or plastic fibers that carry light along their length by means of refraction and are typically used in membrane switches to provide back lighting. A panel is placed directly under the graphic overlay which is composed of one or more layers of optical fibers laminated to a layer of reflective material. The optical fibers are placed next to each other or are interlaced on the reflective material to create an even distribution of light. The opposite end of these fibers, which are bundled into a cable, is terminated into a brass ferrule which is connected to a single remote source of light such as an LED, low intensity incandescent bulb or halogen bulb of varying power. The ability to change a single bulb located nearly anywhere within the device is a key advantage to optical fiber lighting.

Benefits of optical fiber lighting

• Uniform lighting
• Highly flexible
• Long lengths without degradation
• No heat generation
• Non-conductive
• Long life span
• Wide color range

Membrane Switch Electroluminescent Lighting

Electroluminescent lamps (EL lamps) operate as a result of electrically charged electrons releasing their energy as light. they are added under the graphic overlay. They are typically used for ambient lighting of liquid crystal displays but are sometimes used for backlighting of the entire switch. EL lamps can take on complex shapes and can even include internal cutouts without affecting the uniformity of light.

Benefits of electroluminescent lighting

• Resistance to bending
• Uniform directional lighting
• Long life span
• Require minimal energy
• Minimal heat generation
• Available in variety of colors
  

Phosphorescent inks

Phosphorescent inks are made from phosphors such as silver-activated zinc sulfide and typically glows a pale green to greenish blue color. The ink must be exposed to light prior to illumination to store energy. Phosphorescent inks have a sustained glow which lasts for up to 10 hours after exposure to light, but will eventually fade over time. Phosphorescent inks are primarily used for aesthetics and not recommended for critical elements.

Benefits of phosphorescent inks

• Passive light source
• Functions automatically
• Can be printed in any shape or pattern