Color Conversion Sheet With Water Vapor Barrier Resin Sealing
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Solution Overview
Problem
Existing color conversion layers in light emitting devices, particularly those using phosphor layers for backlighting in liquid crystal displays, are prone to deterioration due to water vapor sensitivity, leading to inconsistent chromaticity and reduced light emission efficiency, and are challenging to handle, especially in large and thin displays.
Innovation Solution
A color conversion sheet comprising a phosphor layer sealed by impermeable sealing sheets with a water vapor barrier layer, preventing water vapor entry and enhancing handling and manufacturing simplicity compared to glass substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the phosphor layer is sealed by glass substrates, then the reliability is improved, but the ease of operation deteriorates
Solution Approach 1:
The patent replaces rigid glass substrates with flexible resin sealing sheets that have water vapor barrier properties. These resin sheets provide the necessary protection against water vapor while being significantly easier to handle, bend, and process during manufacturing and installation, directly resolving the contradiction between reliability and ease of operation.
2Reliability
If the phosphor layer is applied inside the outer cap, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent separates the sealing function from the cap structure by using independent resin sealing sheets that are applied to the outer cap surface. This segmentation allows the sealing function to be added as a separate layer without modifying the cap structure or requiring complex internal sealing mechanisms, thus improving reliability while keeping the manufacturing process simple.
Solution Approach 2:
The resin sealing sheets are prepared with water vapor barrier properties in advance, allowing them to be simply applied to the outer cap without requiring complex in-situ sealing processes. This preliminary preparation of sealing materials simplifies the overall manufacturing process while ensuring reliable protection.
3Ease of manufacture
If the phosphor layer is made flat-plate shaped, then the ease of manufacture is improved, but the reliability deteriorates
Solution Approach 1:
The patent uses composite resin sealing sheets that combine flexibility with water vapor barrier properties. These composite materials can be easily applied to flat-plate phosphor layers while providing reliable protection, thus maintaining both ease of manufacture and reliability.
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 effectively suppresses deterioration of the color conversion layer, maintains light emission efficiency, and facilitates easier handling and manufacturing, particularly for large and thin displays, while ensuring reliable performance over extended periods.
Implementation Method 1
an impermeable sealing sheet sealing the color conversion layer
Implementation Method 2
the blue light from the blue LED chip is partly converted into yellow color light in the phosphor layer
Data Source
AI summary
There is provided is a display device capable of suppressing deterioration of the color conversion layer which converts one color light into another color light, and realizing favorable handling and a display device using the color conversion layer, and a color conversion sheet. A phosphor sheet 10 is, for example, arranged immediately above a light source such as a blue light emitting diode, and obtained by sealing a phosphor layer 11, which converts a part of blue light into another color light, by sealing sheets 12A and 12B. The sealing sheets 12A and 12B are bonded with the phosphor layer 11 in between by a first bonding layer 13 and a second bonding layer 14. Since the phosphor layer 11 is sealed by the sealing sheets 12A and 12B including a water vapor barrier layer 122 held between resin sheets 121A and 121B, water vapor is prevented from entering into the phosphor layer, and a chemical reaction is less likely to be generated between the phosphor layer 11 and the water vapor barrier layer 122.