Phosphor Converted LED Lighting Device for High CRI
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Solution Overview
Problem
Current lighting devices, particularly LED-based systems, face challenges in achieving high Color Rendering Index (CRI) while maintaining efficacy, as they often trade off between CRI and efficacy, and existing solutions like adding longer wavelength blue LEDs can introduce complexity and adverse effects such as blue spots in diffusers.
Innovation Solution
The use of multiple phosphor converted LEDs with different wavelength blue excitation sources, combined with red/orange solid state emitters, to produce white light with improved CRI without increasing complexity or causing adverse effects, by providing a mixture of light that is within the acceptable color boundaries and maintaining efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If longer wavelength blue LEDs are added to improve CRI, then CRI Ra increases, but device complexity increases and blue spots appear in diffusers
Solution Approach 1:
The patent extracts the problematic longer wavelength blue LEDs from the system and replaces them with red/orange solid state emitters. This removal eliminates the blue spot issue and complexity while maintaining or improving CRI Ra through the phosphor converted LED design that converts blue light to broader spectrum light including red/orange components.
Solution Approach 2:
The patent changes the spectral parameters by using phosphor converted LEDs with carefully selected phosphor materials that convert blue excitation light into broader spectrum light. This parameter change in the emission spectrum achieves high CRI Ra without requiring additional longer wavelength blue LEDs, thus avoiding the associated complexity and blue spot problems.
2Measurement precision
If multiple light sources are combined to improve CRI, then CRI Ra increases, but efficacy decreases
Solution Approach 1:
The patent merges the functions of multiple light sources into a single phosphor converted LED system. Instead of combining separate blue LEDs, cyan LEDs, and red LEDs, it uses one blue LED excitation source with phosphor materials that generate the full spectrum including red/orange components. This merging maintains high efficacy by using a single efficient blue LED while achieving high CRI Ra through the phosphor conversion process.
Solution Approach 2:
The patent changes the energy conversion parameters by using phosphor materials with high quantum efficiency that convert blue light into broader spectrum light. This parameter optimization ensures that the conversion process maintains high efficacy while producing the spectral components needed for high CRI Ra, avoiding the energy losses associated with combining multiple separate LED sources.
3Use of energy by moving object
If standard phosphor converted LEDs are used, then efficacy is maintained, but CRI Ra is insufficient
Solution Approach 1:
The patent uses composite phosphor materials with specific compositions and characteristics that convert blue LED light into broader spectrum light including red/orange components. These composite phosphor formulations are designed to achieve high CRI Ra while maintaining the high efficacy of the blue LED excitation source, overcoming the limitations of standard single-phosphor systems.
Solution Approach 2:
The patent optimizes the phosphor conversion parameters by selecting phosphor materials with specific emission spectra, quantum efficiencies, and decay characteristics. These parameter optimizations enable the system to maintain high efficacy from the blue LED while generating sufficient red/orange light components to achieve high CRI Ra, surpassing the performance of standard phosphor converted LEDs.
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 enables the achievement of high CRI values, such as Ra 85 or greater, while maintaining or improving efficacy and reducing the likelihood of blue 'hot spots' in diffusers, by using a combination of phosphor converted LEDs with different blue excitation sources and red/orange LEDs to produce white light that is within the acceptable color boundaries.
Implementation Method 1
The use of multiple phosphor converted LEDs with different wavelength blue excitation sources
Implementation Method 2
phosphor converted LEDs with different wavelength blue excitation sources, combined with red/orange solid state emitters, to produce white light
Data Source
AI summary
A lighting device comprising first and second groups of non-white light sources emitting light outside a first area on a 1976 CIE Chromaticity Diagram bounded by a curves 0.01 u′v′ above and below the blackbody locus and within a second area enclosed by saturated light curves from 430 to 465 nm and from 560 to 580 nm and segments from 465 to 560 nm and from 580 to 430 nm and a supplemental light emitter in the range of 600 to 640 nm. Also, a lighting device, comprising a first string of non-white phosphor converted light sources with excitation sources having dominant wavelengths that differ by at least 5 nm, a second string of non-white light sources, and a third string of supplemental light emitters in the range of 600 to 640 nm.