Pyrochlore Wavelength Conversion Units for White Light
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Solution Overview
Problem
Conventional white light sources using blue LEDs and wavelength conversion elements suffer from varying color tones and narrow wavelength bands, leading to poor color rendering properties.
Innovation Solution
A light-emitting element comprising a first and second wavelength conversion unit, each made from pyrochlore-type compounds with specific elemental compositions, where the second unit has a higher content of La, Y, Gd, and Lu, and an interdiffusion layer is formed between them to enhance light emission efficiency and achieve a wide wavelength band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wavelength conversion element is used with a blue LED, then the device structure is simple, but the wavelength band is narrow and color rendering properties are poor
Solution Approach 1:
The single wavelength conversion element is divided into multiple wavelength conversion units (first, second, and third units), each containing phosphors with different emission characteristics. This segmentation allows each unit to contribute to different portions of the spectrum, thereby expanding the overall wavelength band and improving color rendering properties while maintaining a relatively simple layered device structure.
Solution Approach 2:
The invention uses composite phosphor materials within each wavelength conversion unit, combining multiple phosphors (e.g., yellow phosphor, red phosphor, green phosphor) to create a composite system. This composite approach enables the aggregation of emission from multiple phosphors to achieve a broad wavelength band and excellent color rendering, effectively resolving the contradiction between structural simplicity and spectral width.
2Ease of manufacture
If conventional phosphors are used in wavelength conversion elements, then manufacturing is easy, but color tone varies with LED fluctuations and color rendering is poor
Solution Approach 1:
Different wavelength conversion units are designed with specific phosphor compositions optimized for their local function. The first unit contains phosphors for one wavelength range, the second unit for another range, and the third unit for additional ranges. This local quality differentiation ensures that each unit contributes stably to its designated spectral region, making the overall color output less sensitive to fluctuations in the blue LED while maintaining ease of manufacture through modular design.
3Quantity of substance
If multiple wavelength conversion units are used to achieve wide wavelength band, then color rendering improves, but device complexity increases
Solution Approach 1:
The multiple wavelength conversion units are arranged in a layered vertical structure rather than a horizontal arrangement. This dimensional change allows multiple functional units to be integrated in a compact space, expanding the wavelength band through vertical stacking while minimizing the increase in device footprint and overall complexity. The layered configuration enables efficient light propagation through each unit sequentially.
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 results in a light-emitting element that produces white light with excellent color rendering properties and a wide wavelength band, improving light extraction efficiency and maintaining a correlated color temperature between 3000 K to 10000 K.
Implementation Method 1
when the light-emitting element is irradiated with light having a wavelength of 360 nm, a color of mixed light of light emitted from the first wavelength conversion unit and light emitted from the second wavelength conversion unit is white
Implementation Method 2
an interdiffusion layer is formed between them to enhance light emission efficiency
Data Source
AI summary
A light-emitting element that includes a first wavelength conversion unit and a second wavelength conversion unit. The first wavelength conversion unit includes a ceramic containing, as a primary component, a pyrochlore-type compound represented by A1B1Ow1. The second wavelength conversion unit includes a ceramic containing, as a primary component, a pyrochlore-type compound represented by A2B2Ow2. A1 and A2 each include at least one element selected from the group consisting of La, Y, Gd, Yb and Lu, and 0.001 mol % to 5 mol % of Bi. B1 and B2 each include at least one element selected from the group consisting of Sn, Zr and Hf. The content of La in A1 is higher than the content of La in A2. The contents of Y, Gd, and Lu in A2 are higher than the contents of Y, Gd and Lu in A1.