Radiation Imaging Drive Line Voltage Control for Threshold Stability
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Solution Overview
Problem
Radiation imaging apparatuses using amorphous silicon face challenges in generating accurate images due to temperature-related dark image components and amplification circuit instability, particularly in emergency situations where rapid readiness is required, as existing methods either prolong warming-up times or result in unreliable image data from sudden voltage changes.
Innovation Solution
A radiation imaging apparatus with a control unit that applies specific voltage sequences to drive lines, including an OFF voltage for storage, an ON voltage for reading, and a different voltage for threshold voltage shift prevention, allowing for immediate use with reduced temperature drift and stable image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a warming-up operation is performed to achieve a predetermined temperature and reduce dark components, then image reliability is improved, but the time required for readiness increases
Solution Approach 1:
The patent applies preliminary action by performing a warming-up operation before actual radiation imaging to achieve a predetermined temperature and reduce dark components. This ensures that when emergency imaging is required, the system is already in an optimal state for reliable image acquisition, resolving the contradiction between image reliability and warming-up time.
2Productivity
If the voltage applied to photoelectric conversion elements is suddenly raised from ground potential for emergency use, then system readiness is improved, but dark components vary and image data reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by maintaining a predetermined voltage (not ground potential) on photoelectric conversion elements during the warming-up operation. This preliminary voltage application ensures that when emergency imaging is required, the elements are already in a stable state with consistent dark components, allowing immediate reliable imaging without sudden voltage changes.
Solution Approach 2:
The patent applies parameter changes by maintaining a specific predetermined voltage level on photoelectric conversion elements during the warming-up phase, rather than using ground potential. This voltage parameter change ensures stable dark component levels and prevents threshold voltage shifts in thin-film transistors, enabling reliable emergency imaging.
3Reliability
If a warming-up operation is performed with the same timing as normal read drive, then threshold voltage shift is reduced, but the operation takes a long period and threshold still shifts largely
Solution Approach 1:
The patent applies parameter changes by applying a predetermined voltage (different from both ground potential and normal read drive voltage) to photoelectric conversion elements during the warming-up operation. This specific voltage parameter reduces threshold voltage shifts in thin-film transistors while shortening the required warming-up period, resolving the contradiction between threshold stability and time.
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
Enables the generation of stable images with controlled dark image components and reduced temperature drift, ensuring reliable data acquisition even in emergency situations by preventing threshold voltage shifts and maintaining a constant transistor threshold.
Implementation Method 1
amorphous silicon is used for photoelectric conversion elements that are disposed in the radiation imaging apparatus and convert information on light into information on electrons
Data Source
AI summary
A radiation imaging apparatus includes a plurality of pixels, each of which includes a conversion element and a transistor, a plurality of drive lines connected to gates of the transistors, a drive circuit unit configured to supply a voltage to the plurality of drive lines, and a control unit configured to control the drive circuit unit. The control unit performs control of causing the drive circuit unit to apply a different voltage that is between the OFF voltage and the ON voltage and is different from the OFF voltage and the ON voltage to the plurality of drive lines in a different period different from a period in which storage control is performed and a period in which read control is performed.