Display manufacturers strive to improve image quality and brightness while cutting costs. Brightness Enhancement Films (BEFs) meet this need by boosting LCD backlight efficiency.
What is BEF?
A Brightness Enhancement Film (BEF) is a transparent optical film for LCDs and TFTs. It redirects backlight toward viewers to brighten screens without extra power. BEFs optimize backlight efficiency, enhancing contrast and sharpness for vivid viewing. They also enable thinner, more energy-efficient LCD panels.
How Does BEF Work?
BEFs have tiny, precise prism structures on their surface. They use refraction and reflection to boost brightness without more power:
- Refraction: Bends light within a 35° viewing cone toward viewers, maximizing brightness.
- Reflection: Recycles light outside the cone by reflecting it back to the backlight.
A single BEF increases brightness by up to 60%. Dual BEFs (DBEFs), stacked at 90°, boost brightness by up to 120%.
BEF Structure
BEFs typically have 2–4 layers, each with a specific function:
- Base layer: Transparent polycarbonate/polyester for support and stability.
- Reflective layer: Metal/metal oxide layer for DBEFs to reflect light.
- Prismatic layer: Photopolymer core layer with prism structures to redirect light.
- Surface Coating: Acrylic/epoxy layer to protect the film and improve light performance.
Additional layers like adhesive or optical layers may be added for specific needs.
Types of BEF
Manufacturers use these BEF types, often in combination:
- Prismatic/Micro-structured BEFs: Basic, micro-structured films to redirect light.
- DBEFs: Multi-layered films with a reflective polarizer to recycle light.
- Reflective Polarizer Films: Recycle polarized light otherwise absorbed.
- Diffuser Films: Spread light evenly (no brightness boost, but better distribution).
BEF vs. Light Diffuser
- BEF: Enhances on-axis brightness for viewers facing the screen.
- Light Diffuser: Spreads light uniformly, improving viewing angles and comfort (no brightness boost).
Many displays use both for even light and high brightness.
Benefits of BEF
BEFs enhance display efficiency, performance, and user experience:
- Brighter screens without extra power.
- Improved energy efficiency and longer battery life for portable devices.
- Better contrast with deeper blacks and vibrant colors.
- Cost savings via less powerful backlights.
- Improved visibility in bright environments.
- Reduced glare and eye strain.
- Thin, lightweight design for portable devices.
- Versatility across display technologies and sizes.
Conclusion
BEFs provide a simple, effective solution to boost LCD brightness, contrast, and visual quality without extra power. Integrating BEFs achieves better display performance and sustainability, offering brighter, more energy-efficient screens for manufacturers and consumers—without compromising design or cost.