Eu-Doped Phosphor Concentration Gradient Panel
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Solution Overview
Problem
Conventional radiation image converting panels experience significant luminance drops due to fluorescence lifetime deterioration, particularly at high humidity and constant temperature, and are complicated to manufacture with existing moisture-proof protective film structures.
Innovation Solution
A radiation image converting panel with a Eu-doped photostimulable phosphor layer featuring a concentration gradient, where the Eu concentration is higher in the peripheral area than the central area, and a moisture-resistant protective film is used to cover the radiation converting film, optimizing the Eu concentration distribution to suppress luminance drops and maintain uniform fluorescence lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional uniform photostimulable phosphor layer is used, then the manufacturing process is simple, but the luminance drops significantly due to fluorescence lifetime deterioration in high humidity environments
Solution Approach 1:
The patent applies local quality by creating a non-uniform Eu concentration distribution within the photostimulable phosphor layer. The Eu concentration is set to be higher in the peripheral region than in the central region, allowing different parts of the layer to have different properties optimized for their specific functions. This gradient structure suppresses luminance drops in high humidity environments while maintaining manufacturability through a single-layer deposition process.
2Reliability
If a complex multilayer moisture-proof protective film is used, then the photostimulable phosphor layer is protected from moisture deterioration, but the overall panel structure becomes complicated
Solution Approach 1:
The patent extracts the moisture protection function from a complex multilayer protective film structure and integrates it directly into the photostimulable phosphor layer itself. By incorporating the moisture-resistant property into the phosphor layer through specific Eu concentration distribution, the need for separate complex protective films is eliminated, simplifying the overall panel structure while maintaining reliable moisture protection.
3Illumination intensity
If the Eu concentration is increased uniformly across the phosphor layer, then the initial luminance is improved, but the luminance drops more in the peripheral area under high humidity conditions
Solution Approach 1:
The patent applies asymmetry by creating an asymmetric Eu concentration distribution where the concentration varies from the center to the periphery of the phosphor layer. This asymmetric structure compensates for the differential luminance drops that occur in different regions under high humidity conditions, maintaining uniform luminance across the entire panel while preserving high initial luminance output.
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 concentration gradient in the Eu-doped photostimulable phosphor layer effectively reduces luminance drops, particularly in the peripheral areas, ensuring a sufficient fluorescence lifetime for the entire panel while simplifying the manufacturing process with a more straightforward protective film structure.
Implementation Method 1
a radiation converting film which converts an incident radiation ray to a visible light
Implementation Method 2
since a photostimulable excitation light or photostimulable emission is effectively suppressed from diffusing in the horizontal direction (reaches the support body surface while repeating reflection at crack (columnar crystal) interfaces)
Data Source
AI summary
The present invention relates to a radiation image converting panel that effectively prevents deterioration in fluorescence lifetime by a simpler structure. The radiation image converting panel comprises a support body, and a radiation converting film formed on the support body. The radiation converting film is formed on a film forming region which exists within a first main surface of the support body and includes at least a gravity center position of the first main surface. The radiation converting film is doped with Eu, and an Eu concentration distribution has a concentration gradient so as to become higher in the periphery than in the vicinity of the center of the radiation convert film. By thus providing a concentration gradient for the concentration of Eu to be doped, a drop in luminance in the periphery of the radiation converting film can be reduced.