Semiconductor LED Optical Film for Wide-Angle Chromaticity Control
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Solution Overview
Problem
Existing semiconductor light-emitting devices using LEDs with wavelength conversion materials suffer from chromaticity changes and unevenness due to variations in emission angles, particularly with blue and yellow light components, leading to unsatisfactory control of transmittance and chromaticity uniformity.
Innovation Solution
A semiconductor light-emitting device with an optical multilayer film that controls transmittance in both blue and long wavelength regions, ensuring monotonically increasing transmittance in the blue region and decreasing transmittance in the long wavelength region as the emission angle widens, maintaining high transmittance at 550 nm, thereby suppressing chromaticity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an optical multilayer film is used to control blue light transmittance at 0 degrees emission angle, then blue light transmittance is controlled near the center, but blue shift occurs at wider emission angles and yellow light transmittance cannot be controlled
Solution Approach 1:
The optical multilayer film is divided into multiple layers with different functions: first and second multilayer films for controlling blue light at different angle ranges, and a third multilayer film for controlling yellow light. This segmentation allows independent optimization of transmittance control for different wavelength regions and emission angles, resolving the contradiction between achieving chromaticity uniformity and maintaining adaptability across wide emission angles.
Solution Approach 2:
Each multilayer film layer is designed with specific optical characteristics tailored to its function: the first multilayer film has high reflectance for blue light at 0-30 degrees, the second multilayer film has high reflectance for blue light at 30-60 degrees, and the third multilayer film has high reflectance for yellow light. This local quality differentiation enables precise control of chromaticity across the entire emission angle range while maintaining high adaptability.
2Manufacturing precision
If a filter layer is provided to control blue light transmittance in the range of 0 to 30 degrees emission angle, then yellow ring suppression is achieved, but blue shift occurs at wider angles and yellow light control is insufficient
Solution Approach 1:
Multiple multilayer films with different functions are merged into a single integrated optical film structure. The first, second, and third multilayer films are stacked to simultaneously achieve blue light control at multiple angle ranges and yellow light control, thereby improving chromaticity control precision without proportionally increasing device complexity.
Solution Approach 2:
The optical multilayer film structure is designed to perform multiple functions: controlling blue light transmittance at different emission angles, controlling yellow light transmittance, and maintaining overall chromaticity uniformity. This multi-functionality allows a single optical component to address multiple chromaticity control requirements, improving precision without linearly increasing complexity.
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 device achieves uniform chromaticity and high luminosity over a wide range of emission angles by effectively managing transmittance across different wavelength regions, reducing blue shift and yellowish tint variations.
Implementation Method 1
it is possible to suppress the yellowish tint by forming an optical multilayer film on a wavelength conversion part and using wavelength-selective reflection of light by the optical multilayer film
Implementation Method 2
a wavelength conversion material or a layer containing a wavelength conversion material is superimposed on a flat light-emitting surface of an LED
Data Source
AI summary
A light-emitting device includes an optical multilayer film disposed on a light-emitting element that includes an LED element. The optical multilayer film has a transmission spectrum in which, when an angle in a direction perpendicular to a light-emitting surface is 0 degrees and an angle in a direction parallel to the light-emitting surface is 90 degrees, a transmittance increases monotonically in a range of 0 degrees to at least 60 degrees at a peak wavelength of the LED element, a transmittance increases monotonically in a range of 0 degrees to at least 60 degrees at a long wavelength region (650 nm to 700 nm), and a transmittance at 550 nm is 90% or more.