Tilted LED Active Layers for Uniform White Light
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Solution Overview
Problem
Existing light-emitting devices exhibit unevenness in emission color due to the mismatched peak emission wavelengths of blue and green light-emitting diodes, leading to suboptimal color reproducibility and efficiency.
Innovation Solution
A light-emitting device design incorporating a first and second light-emitting element with distinct peak emission wavelengths, a wavelength conversion layer, and a light-guide member, where the angle between the active layers of the light-emitting elements is less than 180 degrees, and a reflective member to enhance light extraction and color uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If blue and green light-emitting diodes with different peak emission wavelengths are mounted on a substrate, then white light emission is achieved, but unevenness in emission color occurs
Solution Approach 1:
The patent introduces a new spatial dimension by tilting the active layers of the blue and green light-emitting diodes at an angle less than 180 degrees relative to each other. This angular arrangement in the third dimension allows light from both LEDs to be extracted more uniformly through the wavelength conversion layer, reducing color unevenness while maintaining white light emission.
Solution Approach 2:
The patent changes the geometric parameter of the active layer orientation angle from the conventional 180 degrees (coplanar) to less than 180 degrees (tilted). This parameter modification optimizes the light extraction path and improves color uniformity across the emission surface.
2Device complexity
If light-emitting diodes are mounted with coplanar active layers at 180 degrees, then device structure is simplified, but color unevenness increases
Solution Approach 1:
The patent moves from a two-dimensional coplanar arrangement to a three-dimensional tilted arrangement of active layers. This dimensional change introduces angular optimization without significantly complicating the overall device structure, as the tilting is achieved through controlled growth or mounting orientation rather than complex mechanical components.
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 effectively reduces color unevenness, improves light extraction efficiency, and enhances color reproducibility by aligning the optical axes of the light-emitting elements and using a reflective member to direct light towards the wavelength conversion layer.
Implementation Method 1
a wavelength conversion layer continuously covering the first element light extracting surface and the second element light extracting surface
Implementation Method 2
a light-guide member covering the first element light extracting surface, the first element lateral surfaces, the second element light extracting surface, and the second element lateral surfaces
Implementation Method 3
a first reflective member covering outer lateral surfaces of the light-guide member
Data Source
AI summary
A light-emitting device includes a first light-emitting element, a second light-emitting element having a peak emission wavelength different from that of the first light-emitting element, a light-guide member covering a light extracting surface and lateral surfaces of the first light-emitting element and a light extracting surface and lateral surfaces of the second light-emitting element, and a wavelength conversion layer continuously covering the light extracting surface of each of the first and second light-emitting elements and disposed apart from each of the first and second light-emitting elements, and a first reflective member covering outer lateral surfaces of the light-guide member. An angle defined by an active layer of the first light-emitting element and an active layer of the second light-emitting element is less than 180° at a wavelength conversion layer side.