Optical Coupler for Display Backlight Light Mixing
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Solution Overview
Problem
Conventional display backlight assemblies using cold-cathode compact fluorescent lights (CCFLs) are limited by fragility, environmental hazards, poor color rendition, inefficient light coupling, and inability to produce a full spectrum of light, leading to reduced display size and efficiency.
Innovation Solution
An edge-lit display backlight assembly that couples a display optical light guide (DOLG) with a solid state light source (SSLS) using an optical coupler, such as an index matching gel or tapered pre-collimation light guide, to improve light management and color mixing, eliminating the air gap and reducing light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a physical gap is maintained between the CCFL and the light guide to prevent damage to fragile fluorescent tubes, then the structural integrity of the CCFL is preserved, but light coupling efficiency deteriorates
Solution Approach 1:
The patent introduces an optical coupler as an intermediary element between the SSLS and the light guide. This coupler serves dual functions: it maintains the necessary physical separation to protect fragile components while simultaneously improving light coupling efficiency through index matching and optical confinement structures. The coupler acts as a mediator that resolves the contradiction between mechanical protection and optical performance.
Solution Approach 2:
The patent changes the refractive index parameter by introducing an optical coupler with a refractive index intermediate between the SSLS and the light guide. This parameter change enables improved light coupling without requiring direct physical contact, thus maintaining structural integrity while enhancing optical efficiency.
2Illumination intensity
If conventional CCFL backlight assemblies are used, then the display can be illuminated, but the color rendition and light spectrum quality deteriorate
Solution Approach 1:
The patent replaces the mechanical/chemical system of CCFL (gas discharge through fluorescent phosphor) with a solid-state light-emitting diode system. This substitution enables superior color rendition and full-spectrum light production while maintaining illumination functionality. The SSLS can be engineered to emit specific wavelengths and color combinations that CCFL cannot achieve.
3Length of stationary object
If edge-lit arrangement with fluorescent tubes is used to produce thinner displays, then the display thickness is reduced, but the range and quality of projected light deteriorates
Solution Approach 1:
The patent replaces edge-lit fluorescent tube illumination with edge-lit solid-state light sources coupled through an optical coupler. This substitution maintains the thin profile advantage of edge-lit designs while dramatically improving light quality, color rendering, and illumination range through the superior optical properties of SSLS and the coupling mechanism.
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
This solution enhances light extraction, color rendition, and illumination efficiency, reducing the need for filters and resulting in thinner, more cost-effective displays with improved resolution and larger display sizes.
Implementation Method 1
an optical coupler, such as an index matching gel or tapered pre-collimation light guide
Implementation Method 2
tapered pre-collimation light guide
Data Source
AI summary
A display backlight assembly providing improved optical coupling between a solid state light source and a display optical light guide. The assembly includes an optical coupler to couple the solid state light source and display optical light guide together. In addition, the optical coupler may include a light mixing element for improved mixing of the multi-colored or mono-chromatic light produced by the solid state light source.