Wavelength Conversion Member Phosphor Gradient Control
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Solution Overview
Problem
Wavelength conversion members with phosphor powder dispersed in a glass matrix often exhibit chromaticity variations, making it difficult to achieve desired luminescent colors with high accuracy.
Innovation Solution
A method for producing a wavelength conversion member with a glass matrix and phosphor particles, where the concentration of phosphor particles decreases from the center towards the surfaces, allowing for precise control of chromaticity through a slurry application, drying, and stacking process, followed by polishing to adjust thickness and chromaticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If phosphor powder is dispersed in a glass matrix and the material is polished to reduce thickness, then the wavelength conversion member can be made thinner, but chromaticity variations occur and manufacturing precision deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform phosphor concentration distribution within the glass matrix. The phosphor concentration is deliberately made higher at the center and lower at the surfaces, resulting in different optical properties at different locations. This local variation in phosphor concentration compensates for the effects of polishing and thickness variations, maintaining chromaticity uniformity across the entire wavelength conversion member.
2Ease of manufacture
If phosphor concentration is uniform throughout the glass matrix, then the manufacturing process is simpler, but chromaticity control precision deteriorates due to variations from polishing
Solution Approach 1:
The patent implements local quality by establishing a controlled non-uniform phosphor distribution pattern. The phosphor concentration varies systematically through the thickness of the glass matrix, with higher concentration at the center and lower concentration at the surfaces. This predetermined local variation enables precise chromaticity control while maintaining ease of manufacture through a standardized production process.
Solution Approach 2:
The patent applies parameter changes by modifying the phosphor concentration parameter as a function of position within the glass matrix. Instead of maintaining a constant phosphor concentration, the patent deliberately varies this parameter through the thickness direction, creating a gradient distribution that optimizes chromaticity performance and compensates for processing variations.
3Length of stationary object
If the wavelength conversion member thickness is reduced, then the device can be more compact, but chromaticity variations increase
Solution Approach 1:
The patent uses local quality to address the chromaticity uniformity problem in thin wavelength conversion members. By creating a phosphor concentration distribution that is higher at the center and lower at the surfaces, the patent ensures that even when the overall thickness is reduced, the local phosphor concentrations remain optimized for uniform chromaticity output, compensating for the reduced total phosphor amount.
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
Enables high-accuracy adjustment of chromaticity in wavelength conversion members, reducing variations and enhancing the precision of luminescent color output.
Implementation Method 1
a wavelength conversion member capable of absorbing part of the light from the LED to convert it to a yellow light
Implementation Method 2
allowing the phosphor particles to sediment downward before completion of the drying
Data Source
Figure 1~3
Figure 4(a)~4(d)
Figure 5
AI summary
Provided is a wavelength conversion member that can be adjusted in chromaticity with high accuracy and a production method therefor. A wavelength conversion member 1 having a first principal surface 1a and a second principal surface 1b opposed to each other includes a glass matrix 2 and phosphor particles 3 disposed in the glass matrix 2, wherein concentrations of the phosphor particles 3 in the first principal surface 1a and in the second principal surface 1b are lower than concentrations of the phosphor particles 3 in surface layer bottom planes 1c and 1d located 20 µm inward from the first principal surface 1a and 20 µm inward from the second principal surface 1b, respectively.