Shaped Wavelength Conversion Element for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Light emitting devices with wavelength conversion elements suffer from high light absorption due to repeated total internal reflections, leading to reduced light extraction efficiency and non-uniform light emission.
Innovation Solution
Shaping the wavelength conversion elements with non-orthogonal surfaces to change the angle of incidence of reflected light, thereby increasing the likelihood of light escaping the device through the light extraction surface, and using diffuse reflective surfaces to further enhance light output uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If orthogonal-sided wavelength conversion elements are used, then manufacturing is simplified, but light extraction efficiency decreases due to repeated total internal reflections
Solution Approach 1:
The patent applies asymmetry by changing the wavelength conversion element geometry from orthogonal sides to non-orthogonal (sloped) sides. This asymmetric design causes internally reflected light to strike the extraction surface at different angles, increasing the probability of escape and reducing repeated total internal reflections that occur with orthogonal geometries.
Solution Approach 2:
The patent employs curved surfaces by sloping the sides of the wavelength conversion element rather than using flat orthogonal surfaces. This curvature modification alters the reflection paths of trapped light, enabling it to intersect the extraction surface within the escape cone angle and improve light extraction efficiency.
2Device complexity
If conventional wavelength conversion elements are used, then device structure is simple, but light emission uniformity deteriorates due to non-uniform light distribution
Solution Approach 1:
The asymmetric sloped geometry redistributes the light paths within the device, causing light that would otherwise be trapped in specific regions to be redirected toward the extraction surface. This creates more uniform light emission across the device area while maintaining relative structural simplicity.
Solution Approach 2:
The patent applies local quality by creating regions with different optical characteristics through the sloped geometry. Different areas of the wavelength conversion element have different light extraction characteristics, which collectively produce more uniform overall light emission by compensating for local variations in light distribution.
3Measurement precision
If orthogonal wavelength conversion elements are used, then internal reflection paths are predictable, but light extraction efficiency decreases due to trapped light
Solution Approach 1:
The asymmetric sloped design intentionally disrupts the predictable orthogonal reflection paths. By creating non-orthogonal surfaces, the patent ensures that light follows diverse reflection paths that increase the probability of intersecting the extraction surface within the escape cone, thereby improving light extraction efficiency.
Solution Approach 2:
The curved sloped surfaces create continuously varying reflection angles rather than the discrete predictable paths of orthogonal surfaces. This curvature-induced path diversity increases the statistical probability that trapped light will eventually strike the extraction surface at an angle within the escape cone and escape.
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
Improves light extraction efficiency by reducing repeated internal reflections and enhances the uniformity of light emission from arrays of light emitting devices.
Implementation Method 1
The wavelength conversion element absorbs some of the light emitted by the light emitting element 150 and emits light at a different wavelength
Implementation Method 2
the indices of refraction of the wavelength conversion element and the surrounding medium will define a critical angle for light extraction, and this critical angle will define an escape cone 168 at each point on the surface 165
Implementation Method 3
light 106, 107 that strikes the surface at an angle greater than the critical angle will experience total internal reflection (TIR), and will be reflected away from the light extraction surface 165
Data Source
AI summary
Pre-formed wavelength conversion elements are attached to light emitting elements and are shaped to reduce repeated occurrences of total internal reflection. The sides of the shaped elements may be sloped or otherwise shaped so as to introduce a change in the angle of incidence of reflected light upon the light extraction surface of the wavelength conversion element. The pre-formed wavelength conversion elements may be configured to extend over an array of light emitting elements, with features between the light emitting elements that are shaped to reduce repeated occurrences of total internal reflection.