Inorganic Phosphor-Glass Composite for LED Thermal Stability
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Solution Overview
Problem
Existing light emitting devices face challenges in reliability due to the deterioration of fluorescent layers in high temperature, high humidity, and sulfur-containing gas environments, and the difference in thermal expansion coefficients between phosphor and reflective materials, leading to reduced luminous efficiency and increased damage rates.
Innovation Solution
A light emitting device design featuring a mount substrate with a light emitting element in a flip-chip configuration, surrounded by a first light transparent member made of inorganic substance and phosphor, and a second light transparent member without phosphor, both covered by a reflective material, which reduces the thickness of the phosphor layer and enhances reliability by minimizing exposure to environmental factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the fluorescent layer is made thicker to improve light conversion, then the luminous efficiency is reduced due to excessive thickness, but making it thinner causes the fluorescent layer to be easily broken and damaged
Solution Approach 1:
The patent uses phosphor-in-glass composite material where phosphor particles are embedded within a glass matrix. This composite structure provides both the light conversion function of phosphor and the mechanical strength, chemical stability, and moisture resistance of glass, resolving the contradiction between achieving thin layer for efficiency while maintaining structural integrity
Solution Approach 2:
The patent changes the physical and chemical parameters of the fluorescent material by encapsulating phosphor in glass, transforming it from a loose powder layer to a solid composite with controlled optical properties. This allows the fluorescent layer to be made thinner while maintaining both luminous efficiency and mechanical strength
2Ease of manufacture
If the fluorescent layer is exposed outside to reduce production cost, then the production cost is reduced, but the fluorescent layer rapidly deteriorates in high temperature, high humidity and sulfur-containing gas environment
Solution Approach 1:
The glass matrix creates an inert protective environment around the phosphor particles, isolating them from harmful external factors such as moisture, oxygen, and sulfur-containing gases. This inert enclosure prevents chemical degradation and maintains fluorescent stability in harsh environments while still allowing cost-effective manufacturing
Solution Approach 2:
The glass layer acts as a protective shell encapsulating the phosphor, providing a barrier against environmental degradation. This thin film structure protects the fluorescent material without adding significant thickness or cost, enabling both reliability and ease of manufacture
3Volume of moving object
If the fluorescent layer and reflective wall are pressed against each other to save space, then the device size is reduced, but they are damaged and peeled off due to difference of material expansion coefficients
Solution Approach 1:
The patent uses glass as both the substrate and encapsulation material for the phosphor, creating a homogeneous structure with matched thermal expansion coefficients. This eliminates the expansion mismatch problem between different materials, allowing the fluorescent layer and reflective wall to be pressed together without peeling or damage while maintaining compact device size
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 improves the reliability and luminous efficiency of light emitting devices by reducing the thickness of the phosphor layer, preventing damage from thermal expansion differences, and maintaining performance in harsh environments.
Implementation Method 1
at least one light emitting element... The light emitting layer is disposed on the n-type semiconductor layer. The p-type semiconductor layer is disposed on the light emitting layer
Implementation Method 2
the first light transparent member is formed of an inorganic substance and an inorganic phosphor
Implementation Method 3
The covering member comprises a light reflective material, and covers at least the first side surface of the first light transparent member
Data Source
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AI summary
A light-emitting device (A1), including a mount substrate (10), at least one light emitting element (20), a first light transparent member (30), a second light transparent member (40) and a covering member (50), is disclosed. The at least one light emitting element (20) is disposed on the mount substrate (10) in a flip-chip manner. The first light transparent member (30) is configured to receive the incident light emitting from the light emitting element (20), wherein the first light transparent member (30) is formed of an inorganic substance and an inorganic phosphor, and includes a top surface (31) and a first side surface (32) contiguous to the top surface (31). The second light transparent member (40) is disposed on the top surface (31) of the first light transparent member (30) and is formed of the inorganic substance and contains no inorganic phosphor, and includes an externally exposed light emission surface (41) and a second side surface (42) contiguous to the externally exposed light emission surface (41). The covering member (50) comprises a light reflective material and covers at least the first side surface (32) of the first light transparent member (30) and at least the second side surface (42) of the second light transparent member (40).