Blue LED White Light Stability via Silicate Fluorescent Layer
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Solution Overview
Problem
Existing white light emitting diodes experience variations in light intensity due to unstable operation voltage and ambient temperature, affecting the color coordinate of the emitted white light, which is not adequately addressed by current multi-chip and fluorescent substance application schemes.
Innovation Solution
A light emitting device comprising a blue light emitting unit and a fluorescent layer with a combination of silicate-based fluorescent substances, including barium, strontium, and calcium, which converts blue light into yellow light, improving light emitting efficiency and maintaining consistent color coordinates by optimizing the light emission spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multi-chip scheme is used to generate white light, then white light can be generated by mixing different colors, but color coordinate becomes unstable due to voltage and temperature variations
Solution Approach 1:
The patent extracts the color mixing function from multiple LED chips and consolidates it into a single blue LED chip combined with a fluorescent layer. This eliminates the need to control multiple chips' light intensities, thereby resolving the color coordinate instability caused by voltage and temperature variations affecting each chip differently.
Solution Approach 2:
The fluorescent layer acts as an intermediary that converts blue light to yellow light, which then combines with the remaining blue light to produce white light. This intermediary conversion process provides a more stable color coordinate compared to directly mixing lights from multiple unstable LED chips.
2Illumination intensity
If fluorescent substance application scheme is used with blue LED chip, then white light can be generated by mixing blue and yellow light, but light emitting efficiency needs improvement
Solution Approach 1:
The patent uses a composite fluorescent layer containing multiple fluorescent substances with different characteristics. This composite structure optimizes the conversion efficiency of blue light to yellow light, thereby improving the overall light emitting efficiency of the white LED while maintaining stable color coordinates.
Solution Approach 2:
The patent optimizes parameters such as the thickness of the fluorescent layer, the composition ratios of different fluorescent substances, and the particle size distribution to maximize light emitting efficiency. By carefully controlling these parameters, the device achieves high efficiency while maintaining color stability.
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 enhances light emitting efficiency and color reproducibility, ensuring consistent brightness and color accuracy across different temperatures and voltages, meeting or exceeding NTSC standards for display devices.
Implementation Method 1
a fluorescent layer (411) receiving the blue light emitted from the blue light emitting unit (410), wherein the fluorescent layer (411) includes a combination of silicate-based fluorescent substances
Data Source
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AI summary
A display device includes a display panel and a light emitting device to supply light to the display panel. The light emitting device includes a light emitting element emitting a first (blue) light and a fluorescent layer receiving the first light, transmitting a portion of the first light, converting a remaining portion of the first light to a second (yellow) light having a wavelength range different from the first light, and emitting a third (white) light. The second light emitted by the fluorescent layer has a full width at half maximum (511) equal to or larger than 110 nanometers (nm) and a light emission spectrum having a peak wavelength within a wavelength range of about 530 nm to about 560 nm. The second light has a peak light emission intensity corresponding to 10 to 30 percent of a peak light emission intensity of the first light.