Curved Waveguide Extraction Features for Unidirectional Illuminance

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Solution Overview

Problem

Conventional lighting systems using optical waveguides face inefficiencies in coupling light from Lambertian sources into waveguides, leading to reduced luminaire efficiency due to light loss at reflection or scattering events and limited direct incidence on coupling surfaces, resulting in glare issues and suboptimal illumination distribution.

Innovation Solution

The luminaire design incorporates an optical waveguide with a first and second surface, featuring extraction features with a curved shape extending between an aperture and a base, optimized to direct at least 80% of light from the source into an illumination distribution from the first surface, minimizing hidden luminance along the line of sight and maximizing optical efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional optical waveguides use Lambertian light sources with traditional coupling surfaces, then light coupling is simpler to implement, but light loss increases due to reflection and scattering events

Engineering Contradiction:

Improvelight lossVSAvoidcoupling structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies curvature to the coupling surface by implementing a spherical cap geometry instead of a flat surface. This curved interface optimizes light coupling from Lambertian LED sources by reducing reflection and scattering losses through proper angular distribution of incident light rays, directly addressing the energy loss problem while maintaining practical device implementation

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If conventional waveguides allow light to exit from multiple surfaces including the back surface, then illumination distribution is more uniform, but glare increases due to visible luminance from unwanted directions

Engineering Contradiction:

ImproveglareVSAvoidillumination distribution

Core Design Contradiction:

Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The patent applies local quality by implementing unidirectional extraction features that are spatially selective. These features are designed to extract light preferentially from the front surface while suppressing extraction from the back surface, creating different optical properties in different locations and directions. This resolves the contradiction by maintaining illumination distribution through selective extraction while eliminating glare from unwanted viewing angles

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements asymmetry through extraction features with specific geometric configurations that favor light extraction in one direction (front surface) over the opposite direction (back surface). The asymmetric geometry of the extraction features creates directional control, allowing uniform illumination distribution from the intended viewing direction while suppressing glare from reverse directions

Inventive Principle:

Principle #4Asymmetry

3Use of energy by moving object

If conventional waveguides use flat coupling surfaces, then manufacturing is simpler, but optical efficiency decreases due to limited direct incidence of light

Engineering Contradiction:

Improveoptical efficiencyVSAvoidmanufacturing simplicity

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent implements a spherical cap coupling surface that optimizes optical efficiency by enabling better direct incidence of light from Lambertian sources. The curved geometry captures a broader angular distribution of light rays compared to flat surfaces, improving coupling efficiency while remaining compatible with standard manufacturing techniques for waveguide fabrication

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 configuration achieves high optical efficiency, with at least 90% of light being directed into the illumination distribution from the first surface, while minimizing luminance visibility from the second surface, thereby reducing glare and enhancing illumination control and directionality.

Implementation Method 1

The optical waveguide mixes and directs light emitted by one or more light sources

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The optical waveguide mixes and directs light emitted by one or more light sources

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

The waveguide includes an extraction feature disposed on the first surface... The extraction feature has a curved shape extending between an aperture adjacent the light emitting surface and a base opposite the aperture

Methodology Applied

Scientific EffectLight extraction through curved surface geometry: Refraction

Data Source

PatentUS10422939B2Waveguide having unidrectional illuminance

Publication Date: 2019.09.24 IDEAL IND LIGHTING LLC

AI summary

A luminaire includes an optical waveguide having a first surface and a second surface opposite the first surface, and a light source associated with the optical waveguide. At least about 80% of light produced by the light source is directed by the waveguide into an illumination distribution emitted from the first surface of the optical waveguide.