Solid State Lighting Device with Segregated Wavelength Conversion Materials
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Solution Overview
Problem
Current solid state lighting devices face challenges in achieving good efficacy, color reproduction, and color stability, particularly in producing warm white light with high color rendering index (CRI) and improved longevity, as existing solutions like blue LED with yellow phosphor or RGB LEDs suffer from low efficacy and color stability issues at elevated temperatures.
Innovation Solution
The use of a lighting device with multiple wavelength conversion materials, including a first light emitting component emitting in the blue spectrum, a second wavelength conversion material emitting in the green spectrum, and optionally a third emitting in the red spectrum, spatially segregated from the first light emitting component, to produce a mixture of light with chromaticity coordinates within specific MacAdam ellipses of the blackbody locus, thereby enhancing color rendering and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If blue LED with yellow phosphor is used, then luminous efficacy is improved, but color rendering index and color stability deteriorate
Solution Approach 1:
The patent segments the wavelength conversion function into multiple independent phosphor materials (yellow phosphor, green phosphor, red phosphor) that are spatially segregated and optically coupled to the blue LED. Each phosphor converts a portion of the blue light to its respective wavelength range, allowing independent optimization of each phosphor's properties to achieve both high efficacy and stable color rendering across operating conditions.
Solution Approach 2:
The patent employs a composite phosphor system combining multiple inorganic phosphor materials with different emission characteristics. This composite approach allows the system to achieve a broad spectrum output with high color rendering index while maintaining the efficiency benefits of LED excitation, resolving the contradiction between efficacy and color quality.
2Reliability
If multiple wavelength conversion materials are used, then color rendering index is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple wavelength conversion materials into a single integrated optical assembly where yellow, green, and red phosphors are positioned in close proximity to the blue LED. This consolidation achieves high color rendering index through the combined spectral output of all phosphors while avoiding the complexity of multiple separate light sources or complex optical systems.
Solution Approach 2:
The patent uses an optical coupling medium or reflective structure as an intermediary to manage the interaction between the blue LED and multiple phosphor materials. This intermediary facilitates efficient energy transfer from the blue LED to each phosphor while maintaining spatial segregation, simplifying the overall device structure compared to alternative approaches.
3Use of energy by moving object
If blue LED with yellow phosphor is used, then luminous efficacy is improved, but color reproduction deteriorates
Solution Approach 1:
The patent segments the spectral output into multiple wavelength components by using separate phosphor materials for different color ranges (yellow, green, red). This segmentation allows each phosphor to contribute to its specific portion of the spectrum while being excited by the same blue LED, achieving both high efficacy and complete color reproduction.
Solution Approach 2:
The patent uses a composite phosphor system that combines materials with complementary emission spectra. The yellow phosphor (Y3Al5O12:Ce3+), green phosphor (β-SiAlON:Eu2+), and red phosphor (CaAlSiN3:Eu2+) work together as a composite system to produce a full-spectrum white light with high color rendering index while maintaining the energy efficiency of LED excitation.
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 achieves a high CRI Ra of 95 or more, improved luminous efficacy, and enhanced color quality, providing warm white light with improved color stability and longevity, suitable for general illumination.
Implementation Method 1
A solid state lighting device produces light (ultraviolet, visible, or infrared) by exciting electrons across the band gap between a conduction band and a valence band of a semiconductor active (light-emitting) layer, with the electron transition generating light at a wavelength that depends on the band gap
Implementation Method 2
A solid state lighting device may include, for example, at least one organic or inorganic light emitting diode (LED) or a laser
Implementation Method 3
A solid state lighting device produces light (ultraviolet, visible, or infrared) by exciting electrons across the band gap between a conduction band and a valence band of a semiconductor active (light-emitting) layer, with the electron transition generating light at a wavelength that depends on the band gap
Data Source
AI summary
A solid state lighting device includes a solid state light emitter combined with a lumiphor to form a solid state light emitting component, at least one lumiphor spatially segregated from the light emitting component, and another lumiphor and/or solid state light emitter. The solid state light emitting component may include a blue shifted yellow component with a higher color temperature, but in combination with the other elements the aggregated emissions from the lighting device have a lower color temperature. Multiple white or near-white components may be provided and arranged to stimulate one or more lumiphors spatially segregated therefrom.