Copper-Activated Phosphor White LED for High CRI and Humidity Stability
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Solution Overview
Problem
Existing white LEDs have limited color temperature range and low Color Rendering Index (CRI), producing cold bluish light and being unstable in humid environments, which hinders mass production and application in various devices.
Innovation Solution
A light emitting device comprising a light emitting diode and a phosphor with a copper-alkaline earth metal based inorganic mixed crystal activated by rare earth elements, converting ultraviolet or blue radiation to visible light with a high color rendering index, and being stable against water and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional phosphors are used in white LEDs, then the structure is simple, but the color temperature range is narrow and CRI is low
Solution Approach 1:
The patent uses composite phosphor materials including copper-activated phosphors combined with rare earth elements (such as Eu, Tb, Dy) to achieve both wide color temperature range (2000K-10000K) and high CRI (>90). The composite structure allows tuning of emission characteristics while maintaining manufacturing feasibility
Solution Approach 2:
The patent adjusts phosphor composition parameters (activator concentration, host material ratios, sintering conditions) to control emission wavelength and intensity, enabling precise control of color temperature and CRI while keeping the manufacturing process relatively simple
2Reliability
If conventional phosphors are used, then manufacturing is easier, but luminescent properties are unstable in humid environments
Solution Approach 1:
The patent employs encapsulation techniques and hermetic sealing to create an inert environment around the phosphor particles, protecting them from moisture and humidity that would otherwise degrade luminescent properties. This approach maintains stability without significantly complicating the manufacturing process
Solution Approach 2:
The use of copper-activated phosphors combined with rare earth elements creates a more chemically stable composite material that resists degradation in humid environments, improving reliability while maintaining ease of manufacture through established ceramic processing techniques
3Productivity
If multiple separate white LED packages are used for general illumination, then each package can be manufactured simply, but the overall device size becomes large and processing steps increase
Solution Approach 1:
The patent integrates multiple light-emitting functions into a single LED package by incorporating multiple phosphor types and activators that can be simultaneously excited by a single blue or UV LED chip, reducing the number of separate packages needed and simplifying assembly while maintaining manufacturing simplicity
Solution Approach 2:
The patent designs a universal phosphor system that can produce multiple color temperatures and high CRI values by adjusting phosphor ratios, allowing a single device structure to serve multiple illumination applications without requiring different package designs
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 provides a wide color temperature range and high CRI, enabling stable and versatile white light emission suitable for various applications, including electronic devices, automobiles, and illumination products.
Implementation Method 1
a wavelength converting element, which includes a phosphor and converts a wavelength of light which is generated from the light emitting diode
Implementation Method 2
a phosphor comprising a copper-alkaline earth metal based inorganic mixed crystal which is activated by rare earths
Data Source
AI summary
The present invention relates to a light emitting device comprising at least one light emitting diode which emits light in a predetermined wavelength region, copper-alkaline earth metal based inorganic mixed crystals activated by rare earths, which include copper-alkaline earth silicate phosphors which are disposed around the light emitting diode and absorb a portion of the light emitted from the light emitting diode and to emit light different in wavelength from the absorbed light.