Wavelength Converting System for Stable LED Color Temperature
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Solution Overview
Problem
Light-emitting diode (LED) systems face challenges in maintaining a stable color temperature when the excitation wavelength changes, leading to inconsistent white light production due to non-uniform wavelength distribution across multiple chips and varying phosphor efficiencies.
Innovation Solution
A wavelength converting system utilizing a combination of YAG and silicate-based phosphors, where the ratio of these phosphors adjusts in response to changing excitation wavelengths to maintain a consistent color temperature, and a carrier supporting light-emitting structures with varying wavelengths to ensure stable emission spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single type of phosphor is used to convert blue light to white light, then the structure is simple, but the color temperature varies significantly when the LED chip wavelength changes
Solution Approach 1:
The patent combines two different phosphors (YAG phosphor and silicate-based phosphor) with different excitation characteristics into a single wavelength converting system. The YAG phosphor responds to blue light around 460nm while the silicate-based phosphor responds to blue light around 475nm, creating a composite phosphor system that maintains stable color temperature across a broader wavelength range
Solution Approach 2:
The patent uses a composite phosphor material system consisting of YAG (Y3Al5O12:Ce) and silicate-based phosphor materials. This composite approach allows the system to leverage the different spectral response characteristics of each phosphor type, achieving stable color temperature output when excited by LED chips with wavelengths varying by 10-20nm
2Adaptability or versatility
If multiple LED chips with different wavelengths are used to increase versatility, then the adaptability improves, but the color temperature uniformity deteriorates
Solution Approach 1:
The patent changes the parameters of the wavelength converting system by introducing a dual-phosphor configuration where each phosphor is optimized for different excitation wavelengths. This allows the system to adapt to LED chips with wavelengths ranging from 460nm to 480nm while maintaining color temperature uniformity within 100K variation
Solution Approach 2:
The patent creates a dynamic response system where the ratio of yellow light to blue light emission changes automatically based on the excitation wavelength. When the LED wavelength shifts, the relative contribution of each phosphor adjusts dynamically to compensate and maintain stable overall color temperature
3Temperature
If phosphor concentration and thickness are adjusted to control color temperature, then the color temperature control improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies different phosphor materials with different local excitation characteristics to the same optical path. The YAG phosphor layer and silicate-based phosphor layer are positioned to both receive the blue LED excitation, with each layer contributing differently based on the exact wavelength, reducing the sensitivity to uniformity variations in a single layer
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 system achieves a color temperature variation of less than 100K across a range of excitation wavelengths, allowing for consistent white light production even with divergent LED chip wavelengths, reducing the need for sorting and binning processes.
Implementation Method 1
A wavelength converting system utilizes a combination of YAG and silicate-based phosphors, where the ratio of these phosphors adjusts in response to changing excitation wavelengths to maintain a consistent color temperature
Implementation Method 2
The peak wavelength difference of the absorption band and the emission wavelength is called 'Stokes shift'
Implementation Method 3
The hole of the p-type semiconductor material and the electron of the n-type semiconductor recombine to emit light under a bias voltage
Data Source
AI summary
An embodiment of the invention discloses a wavelength converting system. The wavelength converting system comprises: a wavelength converter having a first area and a second area; a first light source disposed under the first area and inducing a first mixed light being visible above the first area; a second light source disposed under the second area and inducing a second mixed light being visible above the second area; and a carrier supporting the first light source and the second light source. The first light source and the second light source have a dominant wavelength difference of 1 nm˜20 nm, and the first mixed light and the second mixed light have a color temperature difference less than 100K.