Ce-Activated Aluminate Phosphor LED Spectrum for High Color Rendering
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Solution Overview
Problem
Existing light emitting devices using LEDs struggle with color rendering properties, particularly in achieving high values for special color rendering indexes R9 to R15, and fail to closely mimic the light emission spectrum of sunlight, leading to differences in object visibility when used as a light source.
Innovation Solution
A light emitting device comprising a first and second LED with different peak wavelengths, combined with a Ce-activated aluminate fluorescent material and a nitride fluorescent material, which emit light in specific wavelength ranges to enhance color rendering properties, achieving a mixed light with improved visibility and color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a light emitting device uses a single blue LED combined with yellow-green and red fluorescent materials, then the device structure is simple, but the color rendering property is insufficient with special color rendering indexes R9 to R15 not thoroughly enhanced
Solution Approach 1:
The patent segments the blue light source into two distinct LEDs with different peak wavelengths (430-470nm and 470-490nm). This segmentation allows each LED to excite different fluorescent materials effectively, enabling comprehensive coverage of the visible spectrum and thorough enhancement of all special color rendering indexes R9 to R15, while maintaining a relatively simple overall device structure
Solution Approach 2:
The patent employs composite fluorescent materials including yellow-green fluorescent material (peak 560-580nm), red fluorescent material (peak 610-680nm), and green fluorescent material (peak 500-540nm). This composite approach combines multiple fluorescent materials with different emission characteristics to achieve full-spectrum coverage and excellent color rendering properties (Ra≥90, R9≥90, R10≥90, R11≥90, R12≥90, R13≥90, R14≥90, R15≥90)
2Ease of manufacture
If the light emission spectrum of LED differs from sunlight, then the LED device can be manufactured with current technology, but the visibility of objects under LED lighting differs from natural sunlight conditions
Solution Approach 1:
The patent changes the spectral parameters by using two blue LEDs with different peak wavelengths (430-470nm and 470-490nm) instead of a single blue LED. This parameter change enables the combined light output to more closely match the sunlight spectrum across the visible range, achieving excellent color rendering (Ra≥90) and accurate object visibility while remaining manufacturable with current LED technology
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 device achieves excellent color rendering properties with general color rendering index Ra of 80 or more and special indexes R9 to R15 at 88 or higher, closely matching the light emission spectrum of sunlight across a wide correlated color temperature range, thereby improving object visibility.
Implementation Method 1
a first fluorescent material that is excited by at least one of the first light emitting element and the second light emitting element and emits light having a light emission peak wavelength within a range of 500 nm or more and 540 nm or less, and the first fluorescent material is a Ce-activated aluminate fluorescent material
Implementation Method 2
a light emitting device using an LED is combined with a fluorescent material emitting a yellowish green to green light and a fluorescent material emitting a red light, which are excited by the blue light
Data Source
AI summary
Provided is a light emitting device, including a first light emitting element having a light emission peak wavelength within a range of 400 nm or more and 490 nm or less, a second light emitting element having a different light emission peak wavelength from the first light emitting element within a range of 400 nm or more and 490 nm or less, a first fluorescent material that is excited by at least one of the first light emitting element and the second light emitting element and emits light having a light emission peak wavelength within a range of 500 nm or more and 540 nm or less, and a second fluorescent material, wherein the first fluorescent material is a Ce-activated aluminate fluorescent material containing Lu, Al, and Ga, and optionally at least one element selected from rare earth elements other than Lu.