Radiation Image Detector Edge Field Management
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Solution Overview
Problem
Radiation image detectors face issues with charge injection and discharge breakdown at the edge portions of voltage-applied electrodes, leading to fluctuations in image density and reduced image area due to the concentration of electric fields.
Innovation Solution
A radiation image detector design incorporating a charge injection prevention layer and a protruding electrode, where the charge injection prevention layer covers at least the edge of the voltage-applied electrode, and the protruding electrode is positioned to suppress electric field concentration and charge injection, preventing discharge breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage is applied to the first electrode layer to generate charges in the photoconductive layer, then a radiation image can be recorded, but electric field concentration occurs at the edge portion of the electrode leading to charge injection and discharge breakdown
Solution Approach 1:
The patent applies different properties to different parts of the electrode structure by adding a protruding electrode at the edge portion. This creates a non-uniform electric field distribution that specifically addresses the edge effect problem without affecting the central recording area, thereby preventing discharge breakdown while maintaining image density uniformity.
Solution Approach 2:
The protruding electrode acts as an intermediary element between the voltage-applied electrode and the photoconductive layer. It mediates the electric field distribution by providing a gradual transition at the edge portion, preventing direct charge injection into the photoconductive layer while allowing the main electrode function to remain effective.
2Area of stationary object
If the first electrode layer is extended to increase the image area, then more radiation can be detected, but electric field concentration at the edges increases leading to charge injection
Solution Approach 1:
The protruding electrode is specifically positioned at the edge portion of the first electrode layer to address the local problem of electric field concentration. This allows the electrode area to be extended for larger image coverage while the protruding structure locally modifies the electric field to prevent charge injection at the extended edges.
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 design effectively suppresses charge injection and discharge breakdown, maintaining image density uniformity and preserving the image area by managing electric field concentration and charge transfer.
Implementation Method 1
a photoconductive layer for recording, which generates charges by irradiation with radiation
Implementation Method 2
a photoconductive layer for readout, which generates charges by irradiation with readout light
Data Source
AI summary
In a radiation image detector including a voltage-applied electrode, to which a voltage is applied, and a semiconductor layer for generating charges by irradiation with radiation, which are superposed one on the other, a charge injection prevention layer that covers at least the edge of the voltage-applied electrode is provided. Further, a protruding electrode is provided on the upper surface of the charge injection prevention layer in such a manner that the side surface of an edge of the protruding electrode is located on the outer side of the side surface of the edge of the voltage-applied electrode and the side surface of the other edge of the protruding electrode is located at the position of the side surface of the edge of the voltage-applied electrode or on the inner side thereof.