White LED Lamp Phosphor Balance for Color Rendering
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Solution Overview
Problem
Conventional white LED lamps using ultraviolet emission LEDs have insufficient luminance characteristics due to poor luminous efficiency of red light-emitting phosphors, which affects the balance of blue, green, and red luminescent components, leading to suboptimal color rendering and luminance.
Innovation Solution
A white LED lamp utilizing a semiconductor light-emitting device with a combination of europium-activated halophosphate or aluminate as a blue phosphor, gold and aluminum-activated zinc sulfide as a green phosphor, and europium and samarium-activated lanthanum oxysulfide or copper and manganese-activated zinc sulfide as a red phosphor, optimized to enhance luminance and color rendering by improving the balance of light emission at 450 nm, 560 nm, and 620 nm wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional white LED lamp uses ultraviolet emission LED with BGR phosphors, then color rendering properties are improved, but luminance characteristics deteriorate due to poor luminous efficiency of red light-emitting phosphors
Solution Approach 1:
The patent changes the chemical composition parameters of the red light-emitting phosphor by introducing double activation (europium and samarium) in lanthanum oxysulfide, which fundamentally alters the luminous efficiency parameter from conventional single-activated phosphors to achieve both high color rendering and high luminance
Solution Approach 2:
The patent uses composite phosphor materials including europium and samarium co-activated lanthanum oxysulfide phosphor combined with blue and green phosphors, creating a multi-component phosphor system that achieves balanced color rendering and high luminance output
2Reliability
If red light-emitting phosphor luminous efficiency is poor, then color rendering properties are maintained, but luminance characteristics and balance of luminescent components deteriorate
Solution Approach 1:
The patent modifies the phosphor composition parameters by using double-activated red phosphor (Eu and Sm co-activated) which changes the luminous efficiency parameter from poor to excellent, thereby improving productivity while maintaining color rendering properties
3Illumination intensity
If blue light-emitting LED is combined with yellow phosphor (YAG), then luminance characteristics are improved, but color rendering properties deteriorate causing yellowish appearance and uneven color projection
Solution Approach 1:
The patent replaces simple yellow phosphor with a composite BGR phosphor system (blue, green, and red phosphors) that works with ultraviolet LED to produce full-spectrum white light, achieving both high luminance and excellent color rendering properties
Solution Approach 2:
The patent applies different phosphor materials with specific emission characteristics to different wavelength regions (blue, green, red) to create localized optimization of light emission quality, resulting in balanced full-spectrum output
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 achieves high color rendering properties and improved luminance characteristics by reinforcing the red luminescent component, resulting in a balanced luminance and color rendering index of 90 or more, suitable for various display and lighting applications.
Implementation Method 1
A light emitting diode (LED) is a semiconductor light-emitting device which converts electrical energy into ultraviolet light or visible light to emit it
Implementation Method 2
a light-emitting part which is excited by light from the semiconductor light-emitting device to emit white light, including a blue light-emitting phosphor, a green light-emitting phosphor, and a red light-emitting phosphor
Data Source
AI summary
A white light-emitting lamp (1) includes a semiconductor light-emitting device such as a LED chip (2) which has an emission wavelength of 360 nm or more and 440 nm or less, and a light-emitting part including a blue light-emitting phosphor, a green light-emitting phosphor and a red light-emitting phosphor, which emits white light when excited by light from the LED chip (2). At least one phosphor selected from Eu activated halophosphate phosphors and Eu activated aluminate phosphors is used as the blue light-emitting phosphor, Au and Al activated zinc sulfide phosphor is used as the green light-emitting phosphor, and at least one phosphor selected from Eu and Sm activated lanthanum sulfide phosphors and Cu and Mn activated zinc sulfide phosphors is used as the red light-emitting phosphor.