White LED High Color Rendering Phosphor Layer
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Solution Overview
Problem
Current white LED devices using blue LED chips face challenges in achieving high color rendering properties and luminance due to wide wavelength intervals and material instability, leading to inconsistent color temperature and rendering index, especially for specific colors like R9 and R12.
Innovation Solution
A white light emitting device utilizing a blue LED chip with an excitation wavelength of 440-460 nm and a phosphor layer comprising three phosphors with emission peak wavelengths of 480-499 nm, 500-560 nm, and 600-650 nm, optimized to achieve an average color rendering index of 90% or more and specific indices like R9 and R12 of 90% or more, with a peak wavelength in the range of 485-504 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a blue LED chip is used as an excitation light source with a yellow phosphor, then high luminance is achieved, but the wavelength interval between blue and yellow is wide making it difficult to achieve consistent color coordinates and adjust color temperature and color rendering index
Solution Approach 1:
The patent divides the single yellow phosphor into multiple phosphors with different emission wavelengths (green, red, and yellow-green phosphors). This segmentation allows each phosphor to contribute to specific portions of the spectrum, enabling precise control over color coordinates and color rendering index while maintaining high luminance from the blue LED excitation source.
2Manufacturing precision
If green and red phosphors are used instead of yellow phosphor with a blue LED, then color reproducibility is increased to some extent, but the material stability is poor leading to damage from external energy and unreliable products
Solution Approach 1:
The patent employs a composite phosphor system combining green phosphor (e.g., β-SiAlON:Eu), red phosphor (e.g., CaAlSiN3:Eu), and yellow-green phosphor (e.g., YAG:Ce). This composite approach leverages the complementary strengths of different phosphor materials to achieve both high color reproducibility and improved stability against external energy damage, as the diverse phosphor组合 distributes the stress and energy absorption more effectively than single phosphor systems.
3Manufacturing precision
If multiple LED chips such as R/G/B are combined to emit white light, then color rendering is improved, but non-uniform driving voltage per chip and changes in power depending on ambient temperature produce different color coordinates
Solution Approach 1:
The patent extracts the color mixing function from multiple independent LED chips and consolidates it into a single blue LED chip excitation source that activates multiple phosphors. This eliminates the need for separate driving circuits for each chip, ensuring uniform voltage application and reducing temperature-dependent power variations, thereby stabilizing color coordinates while maintaining improved color rendering.
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 provides high color rendering properties for specific colors, achieving R9 and R12 of 90% or more, and allows for adjustment of wavelength bands and mixing ratios to emit light close to natural light, improving color reproducibility and stability.
Implementation Method 1
a blue LED chip having an excitation wavelength of 440 ̃460 nm
Implementation Method 2
a phosphor layer excited by the excitation wavelength of the blue LED chip to emit light
Data Source
AI summary
The present invention relates to a white light emitting device having high color rendering, and the white light emitting device is a white light emitting lamp comprising a blue LED chip having an excitation wavelength of 440-460 nm, and a phosphor layer covering a light emitting surface of the blue LED chip and excited by the excitation wavelength of the blue LED chip so as to emit light, wherein the phosphor layer comprises a first phosphor having an emission peak wavelength of 480-499 nm; a second phosphor having an emission peak wavelength of 500-560 nm; and a third phosphor having an emission peak wavelength of 600-650 nm. According to aspects of the present invention, a white LED chip having high color rendering can be provided, and particularly, the white light emitting device having high color rendering for specific colors such as R9 and R12 can be provided.