Harnessing the Power of Light with Backlighting Solutions

Do you want to enhance the user experience and differentiate your product from the competition? A great option is to incorporate backlighting solutions into your interface design.



RH provides a wide range of backlighting solutions

We supply our customers with a comprehensive range of backlighting solutions that always provide an excellent option for your Human-Machine Interface (HMI) needs. Backlighting is essential to some customer’s branding, or for other customers, it is a key feature of better device functionality. Therefore, it doesn’t matter if you are creating a membrane keypad, rubber keypad or capacitive touchscreen interface; backlighting can highlight your product and make it stand out from the norm. Backlighting is also crucially important as a feature in low-light environments adding maximum contrast and consistent edge definition.

The selection of backlighting technology:

  • Light Guide Film (LGF)
  • LED’s
  • Acrylic Edge Lit Tiles
  • Electroluminescent (EL)

The benefits of backlighting solutions:

  • Aid visibility in low lighting conditions
  • Predictive hints to guide user operation
  • Operational status and warnings indication
  • Enhance the visual appeal of the product
  • Increase quality perception
  • Branding purposes

Light Guide Film (LGF)

LGF is a thin film backlighting technology that will direct light produced by side-firing or right-angle LEDs across the area that needs to be backlit. Thus, the advantage of Light Guide Film is that it fabricates into almost any shape. The result provides consistent backlighting across one or more areas within the switch.


Light Guide Film (LGF) has the following potential advantages:

  • It is extremely thin for incorporation into membrane switches that can not exceed a certain thickness (i.e. small or lighter devices)
  • LGF has an impact where the tactile feel of buttons is limited.
  • It provides even backlighting across large and small areas. (including applications where the light remains on while the switch is powered.)

Building up multiple LGF layers

The use of multiple films can be used within one application to provide discrete backlighting solutions to different graphic features. Different coloured LEDs work to achieve unique lighting effects, whereas white LEDs can light different printed graphics on the overlay.

Backlighting - gyrocompass


Light-emitting diodes

LEDs are used primarily as indicator lights and are a popular, low-cost, point-source lighting method. Embedded LED’s emit very little heat, and come in a variety of colours including red, yellow, green, blue, white, and bi-colour lamp packages. Depending on the surroundings, various intensities are available. Some LEDs are designed especially for viewing in outdoor environments as opposed to others for indoor use.

Surface-mounted LEDs bonded into our polyester switch construction provides a reliable and cost-effective light source. An even greater variety of lamp packages can be used in PCB Membrane Switches and Copper Flex Switches. These can be through-hole soldered, which enhances durability.

Other features of LED backlighting include:

  • Reliability and long life – typically more than 50,000 hours
  • Low cost
  • Efficient power consumption, operating on low voltages
  • Available in a wide variety of colours, intensities, and lamp packages

Acrylic Edge Lit Tiles

Backlighting - Light Tiles

Acrylic edge-lit tiles use embedded LEDs to light the surface of the tile. The tile has a printed dot pattern on the rear face to make the light even. On the front face of the tile, a special diffusing film hides the dot pattern. This results in a bright and even light over a large area using only 1 or 2 LEDs per tile. The addition of more LEDs will increase the brightness and evenness of larger tiles.

Features of acrylic edge-lit tiles include:

  • The ability to fit tiles with multiple coloured LEDs or RGB LEDs to create colour changing effects.
  • The option to embed 2- 3mm tiles into Keypads or use with overlays to produce backlit areas. (They are particularly good for indicator panels and can be used with capacitive switch panels as well.)
  • Fitting multiple tiles to a PCB assembly to produce an array which can be lit individually or used in conjunction with a secret lit overlay.

Electroluminescent (EL) Lighting

EL lamps contain phosphorus, which converts electrical energy directly into light energy. The high efficiency of this conversion minimises power consumption and reduces losses due to heat or Infra-red emissions. EL backlighting devices consequently consume relatively little power under normal operation. They are best suited for low and no light applications where the backlight is not always on.

Some additional features for EL lamps are:

  • EL lamps consume very little power
  • Provides uniform, balanced backlighting of the entire membrane switch area
  • The thin profile and durability make it suitable for most membrane switch constructions

Other Interfaces