LED Light Extraction via Recessed Wavelength Conversion
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) with wavelength conversion layers suffer from non-uniform color distribution when viewed from different angles due to incomplete absorption of the initial light by phosphor, leading to mixing light with varying ratios of the first and converted light, resulting in non-uniform color and temperature.
Innovation Solution
A light-emitting device incorporating a light-emitting element with a wavelength conversion layer containing wavelength conversion particles of specific sizes (D50 ≤ 10 μm) dispersed in a transparent binder, covered by a light-permeable element and surrounded by a light-reflecting enclosure, which enhances light scattering and conversion efficiency while maintaining uniform color distribution across different view angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a wavelength conversion layer with phosphor is used to convert LED light color, then color conversion is achieved, but non-uniform color distribution occurs when viewed from different angles
Solution Approach 1:
The patent applies local quality by creating a recess structure at the center of the light-emitting element that is laterally overlapped with the wavelength conversion layer. This localized structural modification changes the light path and interaction characteristics in the central region, improving color uniformity for front-view angles while maintaining performance for other viewing angles.
Solution Approach 2:
The patent introduces a dimensional change by creating a recess structure that extends into the light-emitting element from the top surface. This vertical dimensionality modification allows the recess to laterally overlap with the wavelength conversion layer, creating multiple light interaction paths that improve color uniformity across different viewing angles.
2Illumination intensity
If wavelength conversion particles with larger size are used, then light scattering is enhanced, but manufacturing precision and particle size control become more difficult
Solution Approach 1:
The patent applies parameter changes by specifying that the wavelength conversion particles have an equivalent particle diameter D50 of 10 μm or less. This precise parameter control optimizes the balance between light scattering efficiency and manufacturing feasibility, ensuring uniform particle distribution while achieving sufficient light scattering for improved color uniformity.
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 ensures a uniform color distribution and improved light extraction efficiency by optimizing the particle size and concentration of wavelength conversion particles, achieving better light scattering and conversion ratios, thus addressing the non-uniformity issues in conventional LEDs.
Implementation Method 1
Phosphor is a photoluminescence material and is also called a wavelength conversion material. Phosphor can absorb first light from LEDs to emit second light different from the first light.
Implementation Method 2
The recess structure is laterally overlapped with the side surface of the light-emitting element and the wavelength conversion layer
Data Source
AI summary
A light-emitting device includes a light-emitting element, a wavelength conversion layer, a light pervious element and a light-reflecting enclosure. The light-emitting element includes a top surface, a bottom surface, and a side surface between the top surface and the bottom surface. The wavelength conversion layer covers the top surface of the light-emitting element, and includes a plurality of wavelength conversion particles having an equivalent particle diameter D50. The light pervious element includes a recess structure and an outer wall. The light-reflecting enclosure surrounds the outer wall. The D50 of the wavelength conversion particles is not great than 10 μm. The recess structure is laterally overlapped with the side surface of the light-emitting element and the wavelength conversion layer.