Tunable CRI LED Light Source Using Segmented Dies
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Solution Overview
Problem
Current white light sources, particularly LEDs, have fixed color rendering index (CRI) values, which are not tunable, limiting their application in environments where mood or atmosphere modification is desired, such as in mood lighting, decorative lighting, or aquariums, where adjustable lighting effects are needed.
Innovation Solution
The use of multiple light-emitting dies and wavelength-converting materials, such as phosphors, in a light-emitting device configuration allows for tunable CRI by varying the supply current, enabling adjustment of the spectral content and color temperature while maintaining constant CRI, as demonstrated in embodiments with different phosphor combinations and die types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple light-emitting dies with different spectral characteristics are used, then the CRI becomes tunable and spectral content is enriched, but the device complexity increases
Solution Approach 1:
The light source is divided into multiple independent light-emitting dies, each with distinct spectral characteristics (e.g., blue LED die, cyan LED die, green LED die). Each die can be independently controlled to emit light at different wavelengths, enabling segmented spectral management that achieves tunable CRI while maintaining modular device architecture
Solution Approach 2:
Multiple light-emitting dies serve universal functions of light emission across different spectral regions. The same basic LED die structure is used repeatedly with different phosphor coatings or semiconductor compositions, allowing a single device type to perform multiple spectral functions and achieve versatile CRI tuning
2Measurement precision
If multiple wavelength-converting materials are used to enrich spectral content, then CRI value increases, but the manufacturing precision requirements increase
Solution Approach 1:
The invention changes the spectral parameters by selecting light-emitting dies with specifically engineered emission wavelengths and phosphor materials with defined peak emission wavelengths and bandwidths. By carefully selecting and matching these parameters (e.g., blue die at 450nm with cyan phosphor peaking at 490nm), the system achieves precise spectral control and high CRI values through parameter optimization rather than complex manufacturing processes
Solution Approach 2:
The system uses composite phosphor materials combining multiple wavelength-converting components (e.g., cyan phosphor + green phosphor + yellow phosphor) to create broadband emission spectra. These composite phosphor formulations are applied as coatings on LED dies to generate rich spectral content with high CRI values through material composition rather than manufacturing complexity
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 configuration allows for dynamic adjustment of CRI values in response to changes in supply current, enhancing the versatility of lighting applications by enabling different lighting effects and atmospheres without altering the color temperature, thus addressing the need for tunable lighting solutions.
Implementation Method 1
A light-emitting diode (referred to hereinafter as LED) represents one of the most popular light-emitting devices today
Implementation Method 2
The light output of the second group of light-emitting diodes may be converted to a second visible light having a second color temperature and a second spectral content by a second wavelength-converting material, such as a second phosphor
Data Source
AI summary
A light-emitting device with at least two light-emitting dies encapsulated with two different types of the wavelength-converting materials is disclosed. Each of the wavelength-converting materials is configured to produce a visible light from a narrow band light near UV region produced by the light-emitting dies, but with different correlated color temperatures (CCT) and different spectral contents. The combination of the two visible light forms the desired visible white light. The Color rendering index of the light-emitting device is tunable by adjusting the supply current to the light-emitting dies. In another embodiment, a light module with tunable CRI for an illumination system is disclosed.