LED Phosphor Segmentation for Luminous Flux and Color Rendering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor light emitting devices struggle to achieve high luminous flux while maintaining excellent color rendering properties, as they often sacrifice luminous flux for better color rendering index (CRI) and CRI R9 values due to the tradeoff between luminous flux and spectral output across various wavelengths.
Innovation Solution
The use of a recipient luminophoric medium comprising a combination of luminescent materials, including a broad-spectrum green or yellow phosphor, two broad-spectrum red phosphors with peak wavelengths close to each other, and a narrow-spectrum red phosphor, which down-converts light to enhance luminous flux and maintain high CRI and CRI R9 values by concentrating output power at wavelengths sensitive to the human eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor light emitting devices use broad-spectrum phosphors to improve color rendering, then CRI and CRI R9 values are improved, but luminous flux decreases
Solution Approach 1:
The invention segments the red phosphor emission spectrum into two distinct components: a broad-spectrum red phosphor (first red phosphor) for maintaining color rendering quality, and a narrow-spectrum red phosphor (second red phosphor) for boosting luminous flux. This segmentation allows each phosphor to perform its specialized function without compromising the other, resolving the tradeoff between color rendering and luminous output.
Solution Approach 2:
The invention employs a composite phosphor system combining multiple phosphor materials with different spectral characteristics. The composite includes a blue LED chip, yellow phosphor, green phosphor, first red phosphor (broad-spectrum), and second red phosphor (narrow-spectrum). This composite material approach enables the device to simultaneously achieve high CRI values (≥80) and high luminous flux (≥100 lumens) by leveraging the complementary strengths of each phosphor component.
2Productivity
If conventional devices concentrate spectral output at wavelengths sensitive to the human eye to increase luminous flux, then luminous flux increases, but color rendering properties deteriorate
Solution Approach 1:
The invention applies local quality by assigning different spectral characteristics to different phosphor components based on their specific functions. The first red phosphor is designed with broad spectral coverage (FWHM ≥80nm) to ensure color rendering quality in the red region, while the second red phosphor is designed with narrow spectral width (FWHM <60nm) to concentrate energy at peak sensitivity wavelengths for maximum luminous flux. Each phosphor's spectral properties are locally optimized for its designated role.
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 significantly increases luminous flux by up to 10% while maintaining high CRI and CRI R9 values, providing improved color quality and rendering of red hues, with a correlated color temperature between 2700 K and 2850 K and a Qg value of 90 to 110.
Implementation Method 1
a first luminescent material that down-converts a first portion of the light emitted by the LED to light having a first peak wavelength that is in the green color range
Data Source
AI summary
A semiconductor light emitting device includes an LED and an associated recipient luminophoric medium that includes respective first through fourth luminescent materials that down-convert respective first through fourth portions of the radiation emitted by the LED to radiation having respective first through fourth peak wavelengths. The first peak wavelength is in the green color range and the second through fourth peak wavelengths are in the red color range. The second and third luminescent materials each emit light having a full-width half maximum bandwidth of at least 70 nanometers, while the fourth luminescent material emits light having a full-width half maximum bandwidth of less than 60 nanometers. Embodiments that only include three luminescent materials are also disclosed.