Light Emitting Device Phosphor Segmentation for Color Rendering
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Solution Overview
Problem
Conventional light emitting devices struggle to achieve high color rendering properties, particularly in the blue region, due to insufficient radiant intensity, which affects the visual perception of objects and requires additional phosphors to enhance color rendering indices.
Innovation Solution
A light emitting device incorporating a light emitting element with a peak emission wavelength of 410-440nm and a phosphor member comprising five specific phosphors: an alkaline-earth phosphate activated with Eu, an alkaline-earth aluminate, a rare-earth aluminate, a silicon nitride, and a fluorogermanate, optimized to produce a continuous emission spectrum across visible wavelengths, improving color rendering indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a combination of blue LED and yellow phosphor is used to emit white light, then high radiant intensity and high luminous efficiency in visible light region are achieved, but sufficient radiant intensity in blue-green region and red region cannot be obtained, resulting in poor color rendering properties
Solution Approach 1:
The patent divides the phosphor system into five distinct phosphor components, each responsible for a specific wavelength region: first phosphor (430-500nm, blue), second phosphor (440-550nm, green), third phosphor (500-600nm, yellow-green), fourth phosphor (610-650nm, red), and fifth phosphor (650-670nm, deep red). This segmentation allows each phosphor to be optimized for its specific function while collectively achieving high color rendering properties across the entire visible spectrum, resolving the contradiction between efficiency and color rendering.
Solution Approach 2:
The patent employs a composite phosphor system combining five different phosphor materials with specific composition ratios. The first phosphor contains alkaline-earth phosphate with Cl and Eu, the second contains alkaline-earth aluminate or silicate with Eu, the third contains rare-earth aluminate with Ce, the fourth contains silicon nitride with Al and Sr/Ca and Eu, and the fifth contains fluorogermanate with Mn. This composite approach enables the system to achieve both high luminous efficiency and superior color rendering properties by leveraging the complementary emission characteristics of each phosphor material.
2Ease of manufacture
If additional phosphors are added to improve color rendering indices, then color rendering properties are enhanced, but device complexity increases
Solution Approach 1:
The patent assigns specific functional qualities to each phosphor component based on its emission characteristics. The first phosphor is optimized for blue region enhancement, the second for green region, the third for yellow-green region, the fourth for red region, and the fifth for deep red region. Each phosphor's composition and content ratio are locally optimized to address specific color rendering deficiencies, allowing the system to achieve high color rendering properties without requiring excessive complexity in the overall design.
Solution Approach 2:
The patent specifies precise parameter ranges for each phosphor component to optimize the balance between color rendering and device complexity. The content ratios are constrained as follows: first phosphor (20-80 mass%), second phosphor (5-30 mass%), third phosphor (5-30 mass%), fourth phosphor (5-20 mass%), and fifth phosphor (5-20 mass%). Additionally, the content ratio of first phosphor to third phosphor is controlled at 0.3 to 7, and the half value width of the third phosphor is maintained at 95-115nm. These parameter constraints provide a systematic approach to managing complexity while achieving high color rendering properties.
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 high color rendering properties with improved Ra and special color rendering indices, particularly R12, by closely matching the emission spectrum to a reference light source, enhancing visual perception and luminous efficiency while maintaining safety and efficiency as a light source.
Implementation Method 1
a light emitting element having a peak emission wavelength in a range of 410 nm to 440nm
Implementation Method 2
a phosphor member. The phosphor member includes a first phosphor having a peak emission wavelength in a range of 430 nm to 500 nm and containing an alkaline-earth phosphate that has Cl in the composition and activated with Eu
Data Source
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AI summary
A light emitting device includes a light emitting element having a peak emission wavelength of 410 nm to 440nm and a phosphor member. The phosphor member includes a first phosphor having a peak emission wavelength of 430 nm to 500 nm and containing an alkaline-earth phosphate, a second phosphor having a peak emission wavelength of 440 nm to 550 nm and containing at least one of an alkaline-earth aluminate and a silicate containing Ca, Mg, and Cl, a third phosphor having a peak emission wavelength of 500 nm to 600 nm and containing a rare-earth aluminate, a fourth phosphor having a peak emission wavelength of 610 nm to 650 nm and containing a silicon nitride containing A1 and at least one of Sr and Ca, and a fifth phosphor having a peak emission wavelength of 650 nm to 670 nm and containing a fluorogermanate.