Color Conversion Sheet with Inorganic Sealing Films
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Solution Overview
Problem
Existing color conversion phosphor layers in backlight systems are prone to deterioration due to moisture sensitivity, leading to reduced light extraction efficiency and increased thickness, especially when using LEDs for white light extraction.
Innovation Solution
A color conversion sheet with a phosphor layer sandwiched between two sealing sheets, each containing an inorganic stack film on a substrate, where the reflectance characteristics of the sealing sheets on the light incidence and emission sides are optimized to enhance light extraction efficiency and prevent moisture invasion, using silicon nitride or aluminum oxide films with a silicon oxide intermediate for improved adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a phosphor layer is used for color conversion in a backlight, then white light can be extracted using blue light, but the phosphor layer deteriorates when exposed to moisture vapor
Solution Approach 1:
The patent applies sealing sheets with inorganic stack films as protective barriers that sandwich the phosphor layer. These thin film structures effectively block moisture vapor while maintaining light transmission properties, preventing phosphor deterioration without significantly impacting light extraction efficiency
Solution Approach 2:
The patent uses composite inorganic stack films consisting of multiple layers with different properties. The stack includes films with high moisture barrier performance combined with films optimized for light transmission, creating a composite structure that simultaneously protects the phosphor and maintains optical efficiency
2Reliability
If the phosphor layer is sealed by sandwiching it between two glass substrates, then moisture protection is improved, but the device becomes thicker
Solution Approach 1:
The patent replaces thick glass substrates with thin film sealing sheets consisting of inorganic stack films. These films provide equivalent moisture protection functionality while occupying minimal space, thereby maintaining the backlight's thin profile while ensuring phosphor layer protection
Solution Approach 2:
The patent changes the physical state and dimensions of the sealing structure from thick glass substrates to thin film layers. By transitioning to nanometer-scale film thicknesses while maintaining protective functionality, the patent achieves moisture barrier performance without increasing device thickness
3Illumination intensity
If a space for mixing color light is provided in the backlight, then uniform white color is extracted, but the backlight becomes thicker
Solution Approach 1:
The patent applies color conversion directly at the location of the blue light source through the phosphor layer. By converting blue light to other wavelengths locally where the light is generated, the patent eliminates the need for separate mixing spaces, achieving uniform white light output while maintaining a thin structure
Solution Approach 2:
The patent extracts the color mixing function from a separate spatial region and integrates it into the light generation layer itself. By incorporating the phosphor conversion layer directly with the blue LED, the patent removes the need for additional mixing space while maintaining white light quality
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 phosphor layer deterioration and enhances light extraction efficiency, allowing for thinner backlight designs with reduced phosphor material usage, while maintaining durability under high-temperature and high-moisture conditions.
Implementation Method 1
Reflectance of the sealing sheet on the light incidence side in the pair of sealing sheets to the second color light is higher than that to the first color light
Implementation Method 2
reflectance of the sealing sheet on the light emitting side to the first color light is higher than that to the second color light
Implementation Method 3
a color conversion layer converting a part of first color light as incident light to second color light having a wavelength longer than that of the first color light
Data Source
AI summary
A color conversion sheet realizing suppression of deterioration in a color conversion layer and improvement in light extraction efficiency is provided. The color conversion sheet includes: a color conversion layer converting a part of first color light as incident light to second color light having a wavelength longer than that of the first color light; and a pair of sealing sheets sandwiching the color conversion layer from a light incidence side and a light emitting side and each having an inorganic stack film on a substrate. Reflectance of the sealing sheet on the light incidence side to the second color light is higher than that to the first color light, and reflectance of the sealing sheet on the light emitting side to the first color light is higher than that to the second color light.