Fluoro-based Red Phosphor LED Package for Color Purity
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Solution Overview
Problem
Multi-chip type LED systems for emitting white light face issues with color coordinate variation due to uneven operating voltages and output differences among chips, and single-chip systems using phosphors for white light emission often compromise on color purity and luminance.
Innovation Solution
A light-emitting device package incorporating a blue light-emitting device, a green light-emitting device, and fluoro-based red phosphors, with the red phosphors excited by the blue and green light-emitting devices, to achieve high color purity and luminance through a specific phosphor composition and packaging design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multi-chip type method with RGB chips is used to emit white light, then luminous efficacy is improved, but color coordinates vary due to uneven operating voltages and output differences
Solution Approach 1:
The patent segments the white light generation into distinct functional components: a blue light-emitting device (first light-emitting device) and a phosphor layer containing multiple phosphors with different emission characteristics. This segmentation allows independent optimization of each component's performance while maintaining overall color consistency, avoiding the voltage and output matching problems of multi-chip RGB systems.
Solution Approach 2:
The patent employs parameter changes by selecting phosphors with specific emission wavelengths and characteristics (first phosphor emitting yellow light, second phosphor emitting red light, third phosphor emitting green light) and adjusting their proportions in the phosphor layer. This enables precise control of the emitted light's color coordinates and spectral distribution, achieving high color rendering quality without the variability issues of multi-chip systems.
2Device complexity
If single chip type method with phosphors is used to emit white light, then device complexity is reduced, but color purity and luminance are compromised
Solution Approach 1:
The patent uses a composite phosphor layer containing multiple types of phosphors (first phosphor, second phosphor, third phosphor) with different emission characteristics. This composite material approach fills the spectral gaps that would exist with a single phosphor type, achieving high color purity and complete color rendering while maintaining the structural simplicity of a single-chip design. The composite phosphor layer converts the blue light from the single LED chip into a full-spectrum white light with enhanced color properties.
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 enhanced color purity and luminance by providing sharp emission peaks in green and red wavelength ranges, improving color reproduction capacity and reducing the vulnerability of phosphors to environmental factors.
Implementation Method 1
fluoro-based red phosphors, with the red phosphors excited by the blue and green light-emitting devices
Data Source
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Figure 4a
AI summary
Embodiments provide a lead frame, a first light-emitting device disposed on the lead frame and configured to emit light in a first wavelength range and a second light-emitting device configured to emit light in a second wavelength range, which is different from the first wavelength range, and a molding part disposed to surround the first light-emitting device and the second light-emitting device. The molding part includes fluoro-based red phosphors, which are excited by the light emitted from at least one of the first light-emitting device and the second light-emitting device, and the red phosphors have a full width at half maximum within a range from 5 nm to 10 nm.