LED Color Control via Segmented Wavelength-Shifting Layers
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Solution Overview
Problem
Conventional LED-based white light sources suffer from wide color variations, which can lead to yield loss and high manufacturing costs due to inability to meet stringent color specifications.
Innovation Solution
A lighting apparatus is designed with LED dice divided into two groups, each with different amounts of wavelength-shifting material, allowing for adjustment of relative brightness to produce light within a small range of colors, thereby meeting specific color specifications by combining light from groups that produce colors on opposite sides of the target color in the CIE chromaticity diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single amount of wavelength-shifting material is used for all LED dice, then the manufacturing process is simple, but the color variation is wide and color specifications cannot be met
Solution Approach 1:
The LED dice are divided into two groups: first group LED dice with less wavelength-shifting material and second group LED dice with more wavelength-shifting material. This segmentation allows different color outputs from each group, which when combined produce light within a small color range that meets specifications.
Solution Approach 2:
Different amounts of wavelength-shifting material are applied to different groups of LED dice based on their specific needs. The first group receives less material while the second group receives more material, creating local variations in material quantity to achieve uniform overall color output.
2Productivity
If conventional LED-based white light sources are used, then the manufacturing cost is high due to yield loss, but the structure is simple
Solution Approach 1:
By segmenting the LED dice into two groups with different wavelength-shifting material amounts, the system can compensate for variations in individual LED dice performance. This ensures that the combined output meets color specifications, thereby reducing yield loss and improving productivity.
3Manufacturing precision
If LED dice with individual light-conversion layers are used, then color control is improved, but the manufacturing process becomes more complex
Solution Approach 1:
Individual light-conversion layers are applied to different groups of LED dice with different material quantities. The first group receives less wavelength-shifting material while the second group receives more, allowing precise control over the color output of each group to achieve uniform combined color.
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
This approach significantly increases production yield and reduces manufacturing costs by ensuring that substantially all lighting apparatus meet color specifications, with the method applicable to a broader range of color combinations beyond white light sources.
Implementation Method 1
a wavelength-shifting material (e.g., phosphor) to produce light of a target color. The LED dice may emit light of a first color, and the wavelength-shifting material may convert light of the first color to light of a second color
Data Source
AI summary
A lighting apparatus includes a combination of LED dice that emit light of a first color and a wavelength-shifting material (e.g., phosphor) that converts light of the first color to light of a second color. An appropriate combination of light of the first color and light of the second color can be used to produce light of a target color. In an embodiment, LED dice in the lighting apparatus are divided into two groups. Each LED die in the first group is combined with less wavelength-shifting material than needed to produce light of the target color, while each LED die in the second group is combined with more wavelength-shifting material than needed to produce light of the target color. As a result, the two groups produce light having colors on opposite sides of the target color in the International Commission on Illumination (CIE) chromaticity diagram. In some embodiments, the target color and color variations of both groups are on one straight line in the CIE chromaticity diagram, although it is to be understood that there might be small scattering within the groups. By adjusting the relative brightness of the two groups, the target color can be obtained.