LED Color Rendering via Nitride and Halosilicate Phosphors
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Solution Overview
Problem
Conventional light emitting devices with a blue semiconductor light emitting element, red phosphor, and green phosphor fail to achieve sufficient color rendering performance, resulting in objects appearing in different colors compared to fluorescent lamps, especially with a mean color rendering index Ra of 70 or less.
Innovation Solution
A light emitting device comprising a blue light emitting element, a red phosphor formed from a nitride phosphor, a green phosphor formed from a halosilicate, and a YAG phosphor, with specific emission spectrum peaks and relative intensities to enhance color rendering performance, including a red phosphor activated with Eu and green phosphor represented by specific chemical formulas, and YAG phosphor emitting in the yellowish green to yellow range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional light emitting device uses a blue semiconductor light emitting element, red phosphor, and green phosphor, then the device structure is simple, but the color rendering performance is insufficient with a mean color rendering index Ra of 70 or less
Solution Approach 1:
The patent uses a composite phosphor system combining red phosphor (K2SiF6:Mn4+), green phosphor (β-SiAlON:Eu2+), and yellow phosphor (Y3Al5O12:Ce3+) to create a multi-component light emitting device that achieves superior color rendering performance with Ra≥90, resolving the contradiction between simple structure and poor color rendering by integrating multiple phosphor materials with complementary emission characteristics
2Ease of manufacture
If the light emitting device uses only red and green phosphors with blue LED, then the manufacturing process is simple, but the emission spectrum is insufficient covering the visible range
Solution Approach 1:
The patent assigns specific functions to different phosphor materials: red phosphor for long wavelength coverage (600-680nm), green phosphor for middle wavelength (500-560nm), and yellow phosphor for filling the gap (560-580nm). This localized functional assignment ensures comprehensive spectral coverage while maintaining straightforward manufacturing processes
3Reliability
If the light emitting device aims for high color rendering performance, then objects appear in correct colors, but the device complexity increases with multiple phosphor types
Solution Approach 1:
The patent optimizes specific parameters of each phosphor including particle size distribution (0.5-5μm), concentration ratios (red:green:yellow = 100:70-130:20-80), and excitation wavelength matching to achieve Ra≥90 color rendering performance. These parameter optimizations enable high color rendering with a manageable three-phosphor system rather than requiring complex multi-component formulations
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 excellent color rendering performance with a mean color rendering index Ra of 75 or higher and high color reproducibility, balancing color rendering and reproducibility, suitable for various applications including lighting and display backlights.
Implementation Method 1
a red phosphor formed from a nitride phosphor, that emits light when excited by the light from the light emitting element; a green phosphor formed from a halosilicate, that emits light when excited by the light from the light emitting element; and a YAG phosphor that emits light when excited by the light from the light emitting element
Data Source
AI summary
A light emitting device that has excellent color rendering performance is provided.The light emitting device comprises, a light emitting element, a red phosphor formed from a nitride phosphor that emits light when excited by the light from the light emitting element, a green phosphor formed from a halosilicate that emits light when excited by the light from the light emitting element and a YAG phosphor emitting light when excited by the light from the light emitting element.