Radiation Converting Panel Luminance Uniformity

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Solution Overview

Problem

Conventional radiation image converting panels experience significant luminance unevenness on the panel surface after the formation of a protective film, with luminance in the periphery being higher than at the center, leading to reduced image sharpness and quality over time.

Innovation Solution

The radiation image converting panel features a radiation converting film with a controlled film thickness distribution, specifically a convex, W-shaped, concave, or M-shaped sectional shape, allowing for arbitrary adjustment of luminance distribution post-protective film formation, using a Eu-doped photostimulable phosphor layer with columnar crystals tilted at a predetermined angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective film is formed on the surface of the radiation converting film, then the radiation converting film is protected from moisture and deterioration, but luminance unevenness occurs on the panel surface with the periphery having higher luminance than the center

Engineering Contradiction:
Improveprotection from moisture and deteriorationVSAvoidluminance distribution uniformity
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The invention applies local quality by creating a non-uniform film thickness distribution in the radiation converting film, with the center portion having a greater thickness than the peripheral portion. This compensates for the luminance increase in the periphery caused by the protective film, achieving uniform overall luminance across the panel surface.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If the radiation converting film has a uniform thickness, then the manufacturing process is simple, but significant luminance unevenness occurs after protective film formation

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidluminance distribution uniformity
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The invention transitions from uniform film thickness to non-uniform film thickness distribution, where the center portion has a greater thickness than the peripheral portion. This local variation in thickness compensates for the protective film's effect on luminance distribution.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention applies preliminary anti-action by pre-compensating for the luminance unevenness that will occur after protective film formation. The radiation converting film is manufactured with a thicker center portion before the protective film is applied, anticipating and counteracting the future luminance distribution problem.

Inventive Principle:
Principle #9Preliminary anti-action

3Illumination intensity

If the luminance in the periphery of the panel is higher than at the center, then the panel appears brighter overall, but image sharpness and quality deteriorate due to luminance unevenness

Engineering Contradiction:
Improveoverall brightnessVSAvoidimage sharpness
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The invention applies local quality by creating a non-uniform film thickness distribution in the radiation converting film, with the center portion having a greater thickness than the peripheral portion. This compensates for the luminance increase in the periphery caused by the protective film, achieving uniform overall luminance across the panel surface.

Inventive Principle:
Principle #3Local 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

This solution ensures a uniform or enhanced luminance distribution on the panel surface, maintaining or exceeding average luminance levels, thereby improving image quality and reducing luminance unevenness, even after protective film application.

Implementation Method 1

a radiation converting film which converts an incident radiation ray to a visible light

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

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)

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2159604B1Radiation image converting panel
Publication Date: 2019.04.17 HAMAMATSU PHOTONICS KK
  • EP2159604B1 patent drawingFigure 1A~1C
  • EP2159604B1 patent drawingFigure 2A~2C
  • EP2159604B1 patent drawingFigure 3A~3C

AI summary

The present invention relates to a radiation image converting panel with a structure capable of arbitrarily controlling the luminance distribution of the panel surface after formation of a protective film according to usage conditions. 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 existes within a first main surface of the support body and includes at least a gravity center position of the first main surface. The film thickness of the radiation converting film is adjusted such that the maximum difference can be obtained in either one of a peripheral area and a middle area from a central area including the gravity center position.