Dual Light Guide Sheets for Uniform Illumination
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Solution Overview
Problem
Conventional edge-lit illumination systems face challenges in controlling the angular distribution of light, leading to inefficiencies in light emission and uniformity.
Innovation Solution
A shaped illumination device featuring a flexible, curved sheet of optically transmissive material with light extraction elements on its surface, coupled with a reflective material to enhance light distribution and recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional edge-lit illumination systems use a planar light guide with total internal reflection, then light transmission is efficient, but angular distribution control is difficult
Solution Approach 1:
The patent applies local quality by implementing light extraction elements at specific locations and orientations on the light guide surface. These elements are strategically positioned to extract light at particular angles while maintaining TIR for other angles, thereby achieving localized angular control without compromising overall light transmission efficiency.
Solution Approach 2:
The patent changes physical parameters of the light guide system by introducing surface relief features with specific geometries, refractive indices, and orientations. These parameter modifications enable selective light extraction at desired angles while preserving efficient light transmission through the light guide, resolving the contradiction between transmission efficiency and angular control.
2Ease of operation
If light extraction elements are added to control light emission angles, then angular distribution is improved, but light emission efficiency decreases
Solution Approach 1:
The patent applies partial action by implementing light extraction elements that selectively extract only the portion of light needed for angular control, while allowing the majority of light to continue propagating through the light guide via TIR. This partial extraction approach maintains high overall light emission efficiency while achieving the required angular distribution control.
Solution Approach 2:
The light extraction elements are designed with local quality characteristics, where only specific regions of the light guide surface have extraction features. This localized approach ensures that angular control is achieved where necessary without unnecessarily extracting light that would otherwise contribute to efficient illumination, thereby minimizing efficiency loss.
3Illumination intensity
If a curved flexible sheet is used instead of a planar light guide, then light distribution uniformity is improved, but device complexity increases
Solution Approach 1:
The patent implements curvature by forming the light guide as a flexible curved sheet rather than a planar structure. This curvature enables more uniform light distribution across the illumination surface by altering the path and extraction characteristics of light propagating through the guide, achieving improved luminance uniformity.
Solution Approach 2:
The patent employs a flexible thin film light guide that can be curved and conformally mounted. This flexible construction achieves improved light distribution uniformity through curvature while maintaining relatively simple device structure, as the flexibility allows the light guide to adapt to various mounting surfaces without requiring complex rigid support structures.
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 achieves improved light distribution and emission patterns, increasing luminance uniformity and efficiency across the illumination surface.
Implementation Method 1
edge-lit illumination panels employ a planar light guide configured to transmit light in response to an optical transmission and a total internal reflection (TIR)
Implementation Method 2
The light guide typically includes light extracting elements distributed over the surface of the light guide which suppress TIR and cause the light guide to emit light from its broad-area surface
Data Source
AI summary
A lighting fixture includes a linear heat-dissipating structural element with opposing first and second channels. First and second optically transmissive light guide sheets have light input edges and opposing broad-area surfaces. First and second LED strips are thermally coupled to the heat-dissipating structural element and optically coupled to the light input edges of the first and second sheets. First and second pluralities of light extraction elements are formed on broad-area surfaces of the first and second sheets in two-dimensional patterns. At least one light extraction element has a variable thickness with a curved cross-sectional profile and a volume between 1000 and 500000 cubic micrometers. The first and second light guide sheets are symmetrically disposed with respect to the heat-dissipating structural element. An opaque housing partially encloses the LED strips.