Light Emitting Device Chromaticity Adjustment via Narrow Band Phosphors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light emitting devices with blue and green components have difficulty in adjusting chromaticity, which limits their application in achieving high color reproducibility in liquid crystal displays.
Innovation Solution
A light emitting device comprising a first blue light emitting element with a peak wavelength between 430 nm and 490 nm, a second green light emitting element with a peak wavelength between 490 nm and 570 nm, and a light transmitting member containing a red phosphor and at least one of a green phosphor with a narrow emission spectrum and a blue phosphor with a narrow emission spectrum, allowing for adjustable chromaticity and high color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If blue and green light emitting elements are used with fixed emission spectra, then the device structure is simple, but the chromaticity adjustment becomes difficult
Solution Approach 1:
The patent applies parameter changes by introducing phosphors with adjustable emission characteristics. Specifically, it uses a red phosphor (K2SiF6:Mn4+) with a narrow emission spectrum and controls the ratio of red to green phosphors to precisely adjust the overall chromaticity of the light emitting device. This allows chromaticity tuning without changing the basic device structure or light emitting element configuration.
2Adaptability or versatility
If multiple phosphors with wide emission spectra are used, then chromaticity can be adjusted, but color reproducibility decreases
Solution Approach 1:
The patent applies local quality by selecting phosphors with specifically optimized emission spectrum characteristics. It uses a red phosphor with a narrow half-width (≤60nm) and a green phosphor with a narrow half-width (≤45nm), ensuring that each phosphor contributes a well-defined spectral component. This narrow spectral distribution maintains high color purity while still allowing chromaticity adjustment through ratio control.
Solution Approach 2:
The patent uses a composite phosphor system combining K2SiF6:Mn4+ red phosphor with an aluminate green phosphor. The composite material approach allows the device to achieve both chromaticity adjustability and high color reproducibility by leveraging the complementary spectral characteristics of the different phosphors, creating an overall emission spectrum suitable for high-quality display backlights.
3Manufacturing precision
If phosphors with narrow emission spectra are used, then color reproducibility is high, but chromaticity adjustment range is limited
Solution Approach 1:
The patent applies dynamics by making the phosphor composition ratio adjustable. Specifically, it controls the ratio of red phosphor to green phosphor content in the light transmitting member to dynamically adjust the overall chromaticity. This dynamic compositional control expands the achievable chromaticity range while maintaining the narrow spectral characteristics of individual phosphors for high color reproducibility.
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 enables easy adjustment of chromaticity and achieves high color reproducibility in liquid crystal displays by optimizing the emission spectra and ratios of the light emitting elements and phosphors, enhancing the device's performance in backlight applications.
Implementation Method 1
the light transmitting member containing a red phosphor and at least one of a green phosphor and a blue phosphor
Data Source
AI summary
A method for manufacturing a light emitting device includes: mounting a first light emitting element whose emission peak wavelength is in a range of 430 nm to 490 nm and a second light emitting element whose emission peak wavelength is in a range of 490 nm to 570 nm; and providing a light transmitting member including a red phosphor and at least one of a green phosphor of which a half width of an emission spectrum is not more than 45 nm and a blue phosphor of which a half width of an emission spectrum is not more than 60 nm. The step of providing the light transmitting member includes adding at least one of a predetermined amount of the green phosphor and a predetermined amount of the blue phosphor based on the emission peak wavelength of the second light emitting element.