Backlighting: Products & Uses

Backlighting in product manufacturing can have a variety of uses and applications. Common examples are backlight membrane switches and keypads, which are seen in vehicles, keyboards and more. There are two primary options for backlighting displays and panels - Light Guide Film (LGF) and Light Emitting Diodes (LEDs) - and RSP is experienced in both technologies.

Light Guide Film (LGF) in Auto Manufacturing)

Light Guide Film (LGF) Using Side-Fire LED

Light Guide Film (LGF) is one of the most common and flexible technologies when it comes to backlighting. LGF is a cost-effective, flexible film that can take on most shapes and sizes to light most products from within. LGF works by lights shining from sideways (side-fire LED) into the thickness of the film, which is then sent through the film until it encounters a laser etched pocket. This pocket then emits the light.

The LED light used in LGF applications can be a variety of colors, which can shine from behind a logo, keypad and more. Today it is commonly used in vehicles, hand-held devices and nameplates. This application is ideal for illuminating logos and symbols without light creeping out of the etched spaces.

Membrane Switch Backlighting: LED & LGF

How Does LGF Work?

  • Engineering: It takes experience, knowledge and testing to get LGF technology working properly. Most customers simply give us the final specification or desired outcome rather than supplying the exact manufacturing details.
  • Laser Etching: Using a clear carrier layer (like polyester), laser etch and remove material surface at varying depths to capture light from side firing LED light source.
  • LED Light Source: Light from a single to many LED is shot sideways into the light guide film where the light waves travel until they hit a pocket of laser etched material and then it is captured and illuminates the surface. As the LED light progresses further in the clear film, it continues to hit deeper and deeper pockets of laser etched material.

Advantages to LGF film;

  • Low Power: It is great for portable hand-held devices because it uses low power.
  • Colors: Can design with multiple LED colors easily.
  • Flexible / Thin: It is thinner and more flexible than traditional EL lamps.
  • Life: Long lasting with million + hour life.

Membrane Keypad LED/LGF Lighting

LED Indicator Lighting

Traditional LED lighting can be used to act as a simple indicator light. For example, a Green LED is used as a single light indicator in the below image, whereas the “Ground Service ON” button is using LGF technology.

LED indicator lights can be used in a variety of applications in a variety of colors. This technology is typically used in similar scenarios when creative light usage is unnecessary.

Electroluminescent Lamps (EL)

Electroluminescent Lamp (EL) Lighting for Speedometer

The older method for backlighting is Electroluminescent Lamps (EL). EL lamps emit light when material, usually a phosphor, or synthetic phosphorescent substance, is exposed to alternating electrical current. EL Lamps are versatile but may be best known for their use in devices such as wristwatches, clocks, electronic devices, advertising, instrument panel backlighting and even nightlights.

EL Lamps have a half-life of between 3,000 and 5,000 hours depending on the quality of the phosphor used in production and how they are powered.

RSP, Inc. manufactures a wide variety of EL lamp designs, with no minimum order quantities. RSP, Inc. specializes in flat panel EL lamp designs, but can also manufacture rope lights used in decorative lights, DC EL technology, which allows EL lamps to operate on Direct Current, thin film displays and other complex designs.

RSP, Inc. has the expertise to bring a product from concept to realization.
To find out more about RSP Inc.’s EL Lamp capabilities, call 414-546-4417 or send us a message.