Blue LED Lighting with Segmented Green and Red Phosphors
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Solution Overview
Problem
Conventional white LED lighting devices using blue LEDs and YAG phosphors have inferior color rendering properties compared to natural light, and high blue light emission can be harmful to the retina, necessitating cumbersome eyeglasses or filters to reduce blue light exposure.
Innovation Solution
Incorporating a blue LED with a green phosphor emitting light in the 495 nm to 530 nm range and a red phosphor emitting light in the 595 nm to 680 nm range, adjusting the relative spectral areas to significantly decrease blue light emission while maintaining color rendering, by ensuring IB < IG, IB < IR, AB ≤ AG, AB ≤ AR, and AB/(AR+AG) ≤ 0.4.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If blue LED and yellow phosphor are used to create white light, then the lighting device achieves high efficiency and long lifespan, but the color rendering property deteriorates compared to natural light
Solution Approach 1:
The patent segments the yellow phosphor into two distinct components: a green phosphor (emitting 495-530 nm) and a red phosphor (emitting 595-680 nm). This segmentation allows each phosphor to contribute specific wavelength ranges, collectively achieving a broader spectrum that improves color rendering while maintaining the efficiency benefits of LED technology.
2Use of energy by moving object
If blue LED and yellow phosphor are used to create white light, then the lighting device achieves energy efficiency, but the blue light emission harmful to the retina increases
Solution Approach 1:
The patent converts the harmful blue light emission into a beneficial excitation source. The blue LED's emission is used to excite the green and red phosphors, which then emit light in wavelength ranges that are less harmful to the retina. This transforms the potentially harmful blue light into a useful pumping source for generating safer visible light while maintaining energy efficiency.
3Reliability
If green phosphor and red phosphor are added to blue LED to improve color rendering, then the spectrum approaches natural light, but the device complexity increases
Solution Approach 1:
The patent merges the green phosphor and red phosphor into a single integrated phosphor layer that is applied directly to the blue LED chip. This combined approach eliminates the need for separate phosphor layers or complex optical systems, achieving improved color rendering while minimizing structural complexity. The phosphors are positioned to work together in unison with the blue LED emission.
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 effectively reduces blue light emission by a large margin, improving color rendering and minimizing the negative impact on the retina, allowing for safer and more comfortable lighting solutions without the need for additional eyewear or filters.
Implementation Method 1
a green phosphor that by being excited by the emission from the blue LED element emits light having an optical emission peak in the 495 nm to 530 nm wavelength region
Implementation Method 2
a red phosphor that by being excited by the emission from the blue LED element emits light having an optical emission peak in the 595 to 680 nm wavelength region
Data Source
AI summary
LED lighting device in which color-mixed light according to a mixture of a blue optical emission spectrum according to the emission from an LED element, a red optical emission spectrum according to the emission from a red phosphor, and a green optical emission spectrum according to the emission from a green phosphor is emitted, wherein in the spectrum for the emitted color-mixed light, letting the relative spectral area for the principal-wavelength peak of the blue optical emission spectrum be AB and the peak emission intensity be IB, letting the relative spectral area of the green optical emission spectrum be AG and the peak emission intensity be IG, and letting the relative spectral area of the red optical emission spectrum be AR and the peak emission intensity be IR, then IB<IG, IB<IR, AB≦AG, AB≦AR, and AB/(AR+AG)≦0.4.