Optical Waveguide Backlight for Uniform Illumination
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Solution Overview
Problem
Existing backlight systems for large area displays, particularly high dynamic range displays, face inefficiencies in light coupling and heat management, leading to non-uniform illumination and visual artifacts due to crosstalk and increased depth requirements.
Innovation Solution
A novel backlight assembly featuring an array of optical waveguides with inclined reflecting facets and side-mounted LEDs with 120-degree emission angles, combined with spacers and a reflective panel, which enhances light homogenization and coupling through total internal reflections and multiple reflections within the waveguides, allowing for efficient and uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If edge-lit backlight systems are used, then the structure is compact, but the ability to illuminate large displays is limited due to inefficient light coupling and concentrated heat
Solution Approach 1:
The backlight system is divided into multiple independent waveguide modules, each with its own light source array. This segmentation allows each module to efficiently couple light from nearby sources while collectively illuminating large display areas, resolving the contradiction between compact structure and large area illumination capability
Solution Approach 2:
Optical waveguides serve as intermediaries between the light source arrays and the display panel. The waveguides transport and distribute light efficiently across large areas, decoupling the light sources from direct illumination of the display and enabling both efficient light coupling and large area coverage
2Illumination intensity
If direct-lit backlight systems with evenly distributed light sources are used, then uniform illumination is achieved, but the system requires great distance from display and increased depth
Solution Approach 1:
Waveguides act as optical intermediaries that transport light from source arrays positioned at a distance to the display panel surface. This allows uniform illumination to be achieved without requiring the light sources to be placed close to the display, thereby reducing the overall backlight assembly depth
Solution Approach 2:
The system transitions from direct perpendicular illumination to angled light coupling through waveguide facets. By utilizing the lateral dimension for light entry and transport, the system achieves uniform illumination without increasing the vertical distance from the display panel
3Area of stationary object
If multiple light sources are used in direct-lit systems, then large display areas are illuminated, but crosstalk occurs between adjacent LED segments
Solution Approach 1:
The display area is divided into multiple waveguide modules, each handling a specific region. This spatial segmentation prevents light from one module from interfering with adjacent modules, eliminating crosstalk while maintaining large area illumination capability
Solution Approach 2:
The crosstalk problem is addressed by extracting and isolating the light paths of adjacent segments through physical separation into distinct waveguide modules. Each module's light is confined to its designated area, preventing interference with neighboring segments
4Illumination intensity
If volume diffusers and reflector panels are used in direct-lit systems, then illumination is achieved, but light coupling efficiency is reduced due to multiple reflections
Solution Approach 1:
The system replaces multiple mechanical reflections from diffusers and reflector panels with direct optical coupling into waveguides. Light is coupled once at an angle into the waveguide and transported to the display, eliminating the energy losses associated with multiple reflections and improving overall light coupling efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a scalable, efficient, and uniform illumination system that overcomes the limitations of prior art, reducing crosstalk and heat issues, enabling larger display sizes with improved light distribution and reduced visual artifacts.
Implementation Method 1
disposed between reflector panel 22 and the lower light input facet 20 of the optical waveguides 16 are light sources 24... multiple reflections within the waveguides
Implementation Method 2
a light reflector panel 22 that is spaced-apart from the lower surface that comprises light input facets of the optical waveguides... multiple reflections within the waveguides
Data Source
AI summary
A backlight assembly includes an array of optical waveguides that are arranged in rows and columns. The array of optical waveguides has a planar upper surface substantially comprised of light exit facet of optical waveguides and spaced-apart lower surface substantially comprised of light input facet of optical waveguides. Backlight assembly also includes a light reflector panel that is spaced-apart from the lower surface of the array. Disposed between reflector panel and the lower light input facet of the optical waveguides are light sources. Light sources comprise light emitting diodes having 120 degree emission angles.