White LED Phosphor Composition for High-CRI Natural Light
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Solution Overview
Problem
Conventional white LED devices have a low color rendering index (CRI) of approximately 80, making it difficult to emit white light close to natural light, and there is a need for improved color rendering, fidelity index, and Color Gamut Index.
Innovation Solution
A white light emitting device comprising a blue LED chip with a dominant emission wavelength of 440-465 nm, excited by a phosphor layer including blue-green, green, and red phosphors with specific peak emission wavelengths and weight ratios, such as Lu3(Al,Ga)5O12:Ce, Lu3Al5O12:Ce, and CaAlSiN3:Eu, to achieve enhanced color rendering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional white LED device uses blue LED chip with two phosphors, then device complexity is reduced, but color rendering index is low (approximately 80)
Solution Approach 1:
The patent segments the phosphor layer into three distinct phosphor components (blue-green, green, and red phosphors) with specific peak emission wavelengths. This segmentation allows each phosphor to contribute to specific portions of the visible spectrum, thereby improving overall color rendering index from 80 to above 95 while maintaining a relatively simple device structure.
Solution Approach 2:
The patent employs a composite phosphor system combining three different phosphor materials with complementary emission characteristics. The blue-green phosphor (480-519 nm), green phosphor (520-560 nm), and red phosphor (620-670 nm) work together as a composite system to generate a comprehensive spectrum that closely mimics natural light, achieving high CRI without significantly increasing device complexity.
2Use of energy by moving object
If blue LED chip emits at 440-465 nm, then excitation efficiency is improved, but color rendering index remains insufficient
Solution Approach 1:
The patent applies local quality by selecting phosphors with specific peak emission wavelengths that correspond to different regions of the visible spectrum. The blue-green phosphor (480-519 nm), green phosphor (520-560 nm), and red phosphor (620-670 nm) each target specific spectral regions, ensuring that the blue LED chip's excitation at 440-465 nm is efficiently converted into a balanced full-spectrum white light output.
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 emits white light with a high color rendering index (CRI) greater than 95, high Color Fidelity Index (Rf) greater than 93, and Color Gamut Index ranging from 99 to 130, closely mimicking natural light and exhibiting true color representation.
Implementation Method 1
a blue LED chip configured to emit a light having a dominant emission wavelength of about 440-465 nm
Implementation Method 2
a phosphor layer configured to be excited by the light having the dominant emission wavelength of the blue LED chip
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A white light emitting device includes a blue LED chip having a dominant emission wavelength of about 440-465 nm, and a phosphor layer configured to be excited by the dominant emission wavelength of the blue LED chip. The phosphor layer includes a blue-green phosphor having a peak emission wavelength of about 480-519 nm, a green phosphor having a peak emission wavelength of about 520-560 nm, and a red phosphor having a peak emission wavelength of about 620-670 nm. The blue-green phosphor and the green phosphor both have a garnet structure as represented by A3B5O12:Ce, A is selected from the group consisting of Y, Lu, and a combination of thereof, and B is selected from the group consisting of Al, Ga, and a combination of thereof.