Lightguide Surface Texture Design for Uniform Luminance

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Solution Overview

Problem

Edge-lit LED lighting fixtures face challenges in achieving uniform luminance and color distribution due to non-uniform light intensity from LED sources, leading to inadequate optical efficiency and increased system costs, with existing design techniques failing to provide sufficient luminance uniformity and high optical efficiency.

Innovation Solution

A non-uniform surface texture with light extraction features on the lightguide, designed using an iteration algorithm that adjusts feature distribution, geometry, and material composition to achieve desired luminance and color distributions, optimizing for specific applications and reducing the number of LED sources required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a uniform surface texture is used on the lightguide, then the manufacturing process is simple, but the luminance distribution becomes non-uniform due to non-uniform LED light intensity

Engineering Contradiction:

Improvesurface texture fabrication simplicityVSAvoidluminance uniformity

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies local quality by creating zones with different light extraction feature densities matched to the local LED intensity. Areas with higher LED intensity have higher extraction feature density to reduce local luminance, while areas with lower LED intensity have lower extraction feature density to increase local luminance, achieving overall uniform luminance distribution.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The lightguide surface is segmented into multiple zones, each with independently optimized light extraction feature density. This segmentation allows different regions to be tailored to their specific local LED intensity conditions, resolving the contradiction between manufacturing simplicity and luminance uniformity.

Inventive Principle:

Principle #1Segmentation

2Illumination intensity

If more LED sources are used to improve luminance uniformity, then the illumination becomes more uniform, but the system cost and device complexity increase

Engineering Contradiction:

Improveluminance uniformityVSAvoidnumber of LED sources and mechanical constraints

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent changes the parameter of light extraction feature density across different zones of the lightguide to compensate for non-uniform LED intensity. By adjusting this parameter spatially, the system achieves uniform luminance output without adding more LED sources or increasing mechanical complexity.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If light extraction feature density is increased in high-intensity areas, then local luminance is reduced, but optical efficiency decreases due to excessive light extraction

Engineering Contradiction:

Improvelocal luminance controlVSAvoidoptical efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent applies local quality by matching light extraction feature density to local LED intensity conditions. High-intensity areas receive higher extraction density to reduce luminance, while low-intensity areas receive lower extraction density to preserve luminance and maintain optical efficiency.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a feedback-based iterative design process where the optical model calculates luminance distribution, compares it to target uniformity, and adjusts extraction feature density accordingly. This feedback loop optimizes the balance between local luminance control and overall optical efficiency.

Inventive Principle:

Principle #23Feedback

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 high luminance and color uniformity (>65%) and optical efficiency (>65%) while minimizing mechanical design constraints and system costs, suitable for various lighting applications such as office, commercial, and display backlighting.

Implementation Method 1

a lightguide configured with a non-uniform distribution of light extraction features

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

at least one surface having a surface texture comprising a plurality of light extraction features configured to direct incident light out of the lightguide device

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9759852B2Lightguide design techniques

Publication Date: 2017.09.12 OSRAM SYLVANIA INC

AI summary

Techniques are disclosed for obtaining a desired luminance and/or intensity distribution from any lighting fixture that is illuminated by a lightguide. The techniques can be used, for instance, to design a non-uniform surface texture (e.g., of light extraction features) for a lightguide, wherein the surface texture achieves a desired uniform or an intentionally non-uniform luminance distribution for a given lightguide shape/geometry, dimensions, and/or composition. In some embodiments, an iteration algorithm with illuminance distribution feedback is utilized to design a non-uniform surface texture (e.g., geometry, dimensions, quantity and/or spatial distribution of light extraction features) to achieve the target luminance distribution for a given lighting application.