Light Guide Film

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Clad Flat FiberTM

Our Proprietary Light Guide Film Technology

Light guide films typically have a thickness of 0.05” or more, and are made from polymers such as acrylic or polycarbonate. Side view LED’s are attached to the edge of the film. Cutouts can be made in the film to place side view LEDs at the appropriate location. Several technologies exist to extract the light through optical features including laser microdots, half-tone printed inks, and mechanically pressed shapes.

The light rays from the side view LED travel through the film and are refracted upwards towards the surface of the overlay once it hits these optical features, producing an illumination effect. Uniformity of this effect can be controlled through patterns and materials. A back reflector is utilized to further capture any light that is transmitted downward from the light emitting surface. Opaque materials can be utilized to block light in undesired areas.

Our patented Clad Flat Fiber™ (CFF) technology utilizes a tri-extruded film in thicknesses of 0.2mm, 0.3mm or 0.45mm. The core material is acrylic or polycarbonate, and the tri-layer construction adds significant value. The cladding layers provide total internal reflection through the core until we modify it per your needs. The CFF technology allows for a printed back reflector to lower total thickness and improve ease of assembly.

Lumitex can additionally integrate printed circuits onto CFF to eliminate the need for a separate electronics. We engineer a project specific optical design to optimize both light intensity and appearance. As part of the Lumitex Value Added System (L-VAS) we can specify the LED locations, design the electronics, and provide a complete light guide assembly including diffusion layers and brightness enhancing films.

Our Light Guide Film Technology is well suited for the following applications:

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Using Clad Flat Fiber™ Technology


Passenger Control Unit

Membrane switches are electrical controls for turning a circuit on and off. Backlighting a membrane switch is a great way to market the application and make the legends and keys easier to read.

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Portable Ultrasound Equipment

Our customer is proud to be the only U.S. based manufacturer of portable, state-of-the-art, real-time ultrasound scanners for veterinarians and livestock producers world-wide.

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Clad Flat Fiber

Uniform lighting
Developed through proprietary optical processing and controlled through selective etch patterns and materials.

Discreet lighting
Ability to have discreet lighting where it is required including light dams to prevent color bleed.

Thin, low-profile
Our light guide film provides the flexibility to backlight complex shapes and sizes.

Design flexibility
Through color, sizing, layering and quick cost-effective prototypes.

Reflectors, electronics and other components provide flexibility and expertise where needed.

Efficient Design
Highly efficient optical design to minimize power required while optimizing brightness.


Clad Flat Fiber

Standard Sources
Multiple LED Side Emitting standard sources including medical and aerospace grade in all colors, including RGBW.

Standard Materials
3M Adhesives, High Reflective Inks, Flame Retardant Construction.

Overall Design
Optimum LED layout uses a minimum transition of 6mm to properly spread the light. Shorter transition lengths can be accommodated through optical pattern designs and led spacing.

Design Complexity

Light Guide only: Customer supplies their own light source and electronics.

Light Guide and Source Customer only needs to supply power.

Light Guide, Source, Electronics Lumitex provides full integration into customer's design including diffusion layers, brightness enhancing films, electronic components, PCB/FPC's, cabling, and packaging.

Technical Specifications

Clad Flat Fiber

  • Core Material: Polycarbonate
  • Cladding: Acrylic
  • Offered Gauges: .2mm, .3mm, and .45mm
  • Efficiency: Up to 30% or greater
  • Output: up to 1,000nits depending on application and design
  • Core index of refraction: 1.58
  • Numeric Aperture: 0.52
  • Operating Temperature: -40°C to 85°C
  • Relative Humiduty: up to 95 % non-condensing
  • Standard for Uniformity: 50 to 75% typical (Uniformity based on Min/Max calculation)
  • Vicat Softening Temp: 134°C
  • Flexural Modulus for core material: 2500 Mpa
  • Tensile Break Elongation: 9%
  • Lumitex can work with any voltage requirements and will design around the source provided

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