Phosphor Composition for White LED Backlight Color Rendering
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Solution Overview
Problem
Conventional white LED backlights using blue LEDs with yellow phosphors suffer from reduced efficiency and unnatural color representation due to quantum deficits and reradiation inefficiencies, lacking green and red components, and existing phosphors are prone to luminance reduction under high-energy excitation sources.
Innovation Solution
A phosphor composition with the formula A3-zC5O12:REz (0 < z < 0.5), where A includes Y, Sc, or Lu, C includes B or Al, and RE includes Eu, Ce, Sm, Yb, Dy, Gd, Tm, or Lu, offering improved reliability and high luminance, specifically emitting yellow light in the range of 559 nm to 567 nm when excited, suitable for both UV-LED and blue LED applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If YAG:Ce phosphor is coated on blue LED to generate white light, then the white LED backlight is easily driven and inexpensive, but the efficiency is reduced due to quantum deficits and reradiation efficiency, and color rendering is unnatural due to lack of green and red components
Solution Approach 1:
The patent uses a composite phosphor system combining multiple phosphor materials (Y3B5O12:Ce and Y3Al5O12:Ce) with different emission characteristics. This composite approach allows simultaneous achievement of high efficiency (yellow phosphor for energy conversion) and natural color rendering (green and red phosphors for color completeness), while maintaining ease of manufacture through proven coating techniques.
2Ease of manufacture
If silicate phosphor is used in backlight unit or lighting device, then it has been used for a long time, but the reliability is inferior due to weakness to moisture
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material from moisture-sensitive silicate to moisture-resistant borate (Y3B5O12) and aluminate (Y3Al5O12) structures. This parameter change maintains the phosphor's luminescent properties while dramatically improving reliability by eliminating moisture sensitivity, and ease of manufacture is preserved through established ceramic processing methods.
3Illumination intensity
If conventional phosphor is exposed to high energy excitation source such as ultraviolet light or blue light, then it can emit visible light, but the luminance of the phosphor is reduced
Solution Approach 1:
The patent modifies the phosphor's chemical composition to Y3B5O12:Ce and Y3Al5O12:Ce with optimized rare earth doping concentrations (0.01 ≤ z ≤ 0.5). This parameter optimization enhances the phosphor's resistance to photodegradation and thermal quenching under high-energy excitation, maintaining high luminance output over extended operational durations.
4Ease of operation
If blue LED is combined with yellow phosphor in white LED backlight, then it is easily driven and inexpensive, but green and red components are lacking so colors are unnaturally represented
Solution Approach 1:
The patent implements a multi-phosphor composite system where Y3B5O12:Ce provides yellow emission (559-567 nm) for efficiency, while additional green (530-540 nm) and red (610-630 nm) phosphors complete the spectrum. This composite approach achieves natural color rendering (high CRI) while maintaining ease of operation through standard LED driving circuits and phosphor coating processes.
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 phosphor composition enhances light emission intensity and color rendering index, enabling the use of white LEDs in various applications, including mobile devices, vehicles, and medical lighting, with improved reliability and luminance stability.
Implementation Method 1
a phosphor for a white LED, which is excited by an excitation source having high energy such as ultraviolet light or blue light to emit visible light
Data Source
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AI summary
Disclosed are a phosphor composition and a light emitting apparatus including the same. The phosphor composition has a compositional formula of AzCxO12:RE, wherein the z is 0≤z≤3, the x is 0≤x≤5, the A includes at least one selected from the group consisting ofY, Sc, Gd and Lu, the C includes at least one selected from the group consisting of B, A1 and Ga, and the RE includes at least one selected from the group consisting of Eu, Ce, Sm, Yb, Dy, Gd, Tm and Lu. The light emitting apparatus includes the phosphor composition.