Wavelength-Converted LED Coating for Precise Color and Luminous Flux
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Solution Overview
Problem
Current semiconductor light-emitting devices face challenges in precisely controlling emission colors and improving luminous efficiency, as they struggle to effectively convert and transmit light wavelengths efficiently.
Innovation Solution
A light-emitting device is designed with a semiconductor light-emitting structure, a wavelength conversion layer, and a multi-inorganic-film coating layer, where the multi-inorganic-film coating layer includes a distributed Bragg reflector structure with alternately stacked inorganic films, allowing for controlled transmission of light wavelengths and enhancing luminous flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional single-layer coating is used, then the structure is simple, but the emission color control precision is insufficient
Solution Approach 1:
The coating layer is segmented into multiple inorganic film layers with different refractive indices and thicknesses. Each layer is designed with specific optical properties to control light transmission and reflection at different wavelengths, enabling precise emission color control through the cumulative effect of multiple segmented layers rather than a single homogeneous coating
Solution Approach 2:
The patent employs composite inorganic film structures combining materials with different optical characteristics (refractive indices). This composite approach allows the coating to simultaneously transmit blue light while reflecting other wavelengths, achieving precise color control that cannot be obtained with single-material coatings
2Productivity
If more phosphors are used to improve luminous efficiency, then the luminous flux increases, but the fabrication cost increases
Solution Approach 1:
The patent replaces the reliance on phosphor quantity (material-based approach) with an optical interference-based coating system. The multi-layer inorganic coating uses optical principles (transmission and reflection interference) to enhance luminous flux without requiring proportional increases in phosphor material, thereby reducing fabrication costs while maintaining or improving luminous efficiency
3Reliability
If the coating layer is placed close to the light-emitting surface, then the structure is compact, but the light transmission and reflection control is insufficient
Solution Approach 1:
The patent optimizes the distance parameter between the coating layer and light-emitting surface, along with individual layer thicknesses and refractive indices. By carefully adjusting these parameters, the coating achieves maximum optical control effectiveness at a specific distance, balancing the need for compact structure with the requirement for reliable light transmission and reflection control
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 enables precise control of emission colors and improves luminous efficiency by reducing the amount of phosphors needed, thereby lowering fabrication costs and increasing the degree of freedom in selecting emission colors without complex structural changes.
Implementation Method 1
a wavelength conversion layer facing the light-emitting surface and configured to convert at least a portion of the light which has the first wavelength into light having a second wavelength that is greater than the first wavelength
Implementation Method 2
The multi-inorganic-film coating layer includes a distributed Bragg reflector (DBR) structure including a plurality of inorganic films, in which a first inorganic film having a first refractive index and a second inorganic film having a second refractive index are alternately stacked
Data Source
AI summary
A light-emitting device includes: a semiconductor light-emitting structure configured to emit light having a first wavelength; a wavelength conversion layer configured to convert the light which has the first wavelength into light having a second wavelength that is greater than the first wavelength; and a multi-inorganic-film coating layer spaced apart from a light-emitting surface with the wavelength conversion layer therebetween. The multi-inorganic-film coating layer includes a distributed Bragg reflector structure in which first and second inorganic films are alternately stacked, and an uppermost inorganic film farthest from the wavelength conversion layer from among the plurality of inorganic films has a greatest thickness in a first direction perpendicular to the light-emitting surface of the semiconductor light-emitting structure. The first refractive index is selected from a range of about 1.1 to about 1.5, and the second refractive index is selected from a range of about 2.0 to about 3.0.