Transparent Ceramic Phosphor for LED Light Extraction
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Solution Overview
Problem
Conventional light emitting apparatuses face challenges in achieving high light-extraction efficiency due to opaque phosphor powders absorbing and scattering light, limited durability from ultraviolet exposure, and difficulties in controlling phosphor concentration and injection amounts, leading to uneven color tones and reduced productivity.
Innovation Solution
The use of transparent ceramic phosphors with controlled transparency and surface roughness to effectively extract light without absorption or scattering, eliminating the need for resin-suspension liquids and allowing for uniform phosphor distribution, thereby enhancing light extraction efficiency and industrial production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If opaque phosphor powders are used for wavelength conversion, then the phosphor can effectively absorb light, but the light emitted from the phosphor is absorbed and scattered by outer phosphor particles, reducing light extraction efficiency
Solution Approach 1:
The patent changes the physical state parameter of the phosphor from opaque powder to transparent ceramic. This parameter change allows the phosphor to maintain light absorption capability while eliminating light scattering and absorption by outer phosphor particles, thereby resolving the contradiction between effective light absorption and light extraction efficiency
Solution Approach 2:
The patent uses composite material structure by combining transparent ceramic phosphor with resin material. The transparent ceramic phosphor provides effective light absorption and conversion, while the transparent resin matrix allows emitted light to extract efficiently without being scattered by phosphor particles, thus resolving the contradiction
2Illumination intensity
If phosphor powder concentration is increased to improve color uniformity, then more light can be converted, but the resin-suspension system becomes difficult to control, leading to uneven color tones and reduced productivity
Solution Approach 1:
The patent changes the form factor parameter of the phosphor from fine powder to ceramic piece. This parameter change eliminates the need for suspension and concentration control, allowing the phosphor to be directly mounted on the LED chip. The concentration uniformity problem is naturally resolved, and productivity is improved by eliminating the complex slurry injection and drying processes
3Use of energy by moving object
If ultraviolet light is used to excite phosphor, then wavelength conversion can be achieved, but the resin material deteriorates under ultraviolet exposure, limiting durability
Solution Approach 1:
The patent replaces the resin-suspension system with a direct ceramic mounting system. The transparent resin is no longer needed as a suspension medium, eliminating its deterioration under ultraviolet exposure. The ceramic phosphor is directly mounted on the LED chip using adhesive, removing the durability limitation caused by resin degradation while maintaining wavelength conversion capability
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 luminous intensity and uniform color emission while improving industrial productivity by using transparent ceramic phosphors with specific transmission ranges and surface characteristics, effectively addressing the limitations of opaque phosphors and resin-based systems.
Implementation Method 1
a light emitting apparatus in which a light emitted from a light emitting diode is subjected to a wavelength conversion by a ceramic phosphor
Data Source
AI summary
The present invention relates to a light emitting apparatus including a semiconductor light emitting element and a transparent ceramic phosphor for converting a wavelength of a light emitted from the semiconductor light emitting element, wherein the semiconductor light emitting element emits an ultraviolet light, and the ceramic phosphor corresponding to the semiconductor light emitting element has (i) a minimum transmission of 0.1 to 40% under a wavelength of 350-420 nm and (ii) a transmission of 10 to 90% under an emission peak wavelength of the ceramic phosphor.