Light Emitting Device with Nitride Fluorescent Material
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Solution Overview
Problem
Existing light emitting devices based on LEDs have uneven radiant flux intensity distribution and poor color rendering performance, making them inadequate for producing a continuous spectrum similar to natural or incandescent light, which affects the perceived color of objects and requires complex control and UV emission management.
Innovation Solution
A light emitting device comprising a short-wavelength visible light source and a wavelength converting member that emits light with a specific energy intensity ratio, achieving a continuous spectrum with improved color rendering performance and reduced UV emission, using a nitride fluorescent material activated with rare earth elements to enhance red region intensity and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a blue LED and YAG fluorescent material are combined to emit white light, then power consumption is reduced and control is simplified, but radiant flux intensity distribution becomes uneven in the visible light region
Solution Approach 1:
The patent combines multiple fluorescent materials (YAG and red fluorescent material) with a blue LED to create a composite light emitting device. This composite structure enables the device to maintain low power consumption while achieving more uniform radiant flux intensity distribution across the visible spectrum by complementing each other's emission characteristics.
Solution Approach 2:
The patent merges the emission spectra of blue LED, YAG fluorescent material, and red fluorescent material into a unified white light output. By combining these light sources with different spectral characteristics, the device achieves both energy efficiency and improved illumination quality with balanced radiant flux distribution.
2Productivity
If multiple LEDs are combined to improve efficiency and color rendering, then power consumption is reduced and display color range is widened, but device complexity and control difficulty increase
Solution Approach 1:
The patent combines a blue LED with multiple fluorescent materials (YAG and red fluorescent material) into a single integrated light emitting device. This merging approach maintains high efficiency and wide color rendering while simplifying control compared to using multiple independent LEDs, as only one LED driver is needed.
Solution Approach 2:
The blue LED serves multiple functions: it directly provides blue light for display and simultaneously excites both YAG and red fluorescent materials to generate yellow and red light components. This multi-functionality improves efficiency while reducing the number of separate light sources needed.
3Illumination intensity
If ultraviolet LED and fluorescent material are used to reduce radiant flux unevenness, then continuous spectrum is achieved, but ultraviolet ray emission requires management and luminous efficiency decreases
Solution Approach 1:
The patent changes the excitation wavelength parameter from ultraviolet to blue light range. By using a blue LED (wavelength ~450nm) instead of ultraviolet LED, the device achieves the same goal of uniform radiant flux distribution through fluorescent materials while eliminating harmful ultraviolet emission and improving luminous efficiency.
Solution Approach 2:
The patent converts the potential harm of ultraviolet radiation into a beneficial approach by using visible blue light for excitation. This substitution maintains the advantage of continuous spectrum generation through fluorescent materials while converting a harmful parameter (UV emission) into a safe and useful parameter (visible blue light for display).
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 solution provides a light emitting device with a continuous emission spectrum and high color rendering performance, mitigating uneven radiant flux intensity and improving luminance, while avoiding the need for UV emission management and maintaining high luminance and color rendering indices.
Implementation Method 1
a wavelength converting member that absorbs light from the exciting light source and emits light of a wavelength longer than that of the light from the exciting light source
Implementation Method 2
using a nitride fluorescent material activated with rare earth elements to enhance red region intensity
Data Source
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AI summary
A light emitting device includes a wavelength converting member for absorbing light emitted by an exciting light source and emitting light of a different wavelength. With a wavelength at which the light from the exciting light source has a maximum energy intensity denoted as a first wavelength, a wavelength at which the light from the wavelength converting member has a maximum energy intensity denoted as a second wavelength, a wavelength lying between the first and second wavelengths at which the light from the light emitting device has a minimum energy intensity denoted as a third wavelength, and 650 nm denoted as a fourth wavelength, then the light emitting device has an emission spectrum such that the proportion of the energy intensity at the first wavelength to the energy intensity at the third wavelength is in a range from 100:15 to 100:150, and the proportion of the energy intensity at the first wavelength to the energy intensity at the fourth wavelength is in a range from 100:45 to 100:200.