Radiation Imaging Apparatus Reset Timing Control
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Solution Overview
Problem
Radiation imaging apparatuses face challenges in detecting radiation effectively due to signal charge loss during the reset operation, leading to artifacts in images and reduced detection capability, especially when the conducting time period of transistors is prolonged.
Innovation Solution
The apparatus performs a reset operation by sequentially setting transistors to a conducting state in a matrix of conversion elements, followed by an accumulation operation and a readout operation, with varying time cycles to minimize signal charge loss and enhance detection capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conducting time period of the transistor in the reset operation is made longer to enhance reset efficiency, then the reset operation becomes more effective, but signal charge loss increases and image artifacts become more prominent
Solution Approach 1:
The patent divides the reset operation into multiple sequential reset operations performed at different time cycles. Instead of a single long reset pulse, the system performs multiple shorter reset cycles, each with its own conducting time period. This segmentation allows the transistor to be reset multiple times without maintaining a continuously long conducting state, thereby reducing signal charge loss while ensuring adequate reset efficiency.
Solution Approach 2:
The patent implements periodic reset operations where the transistor is cycled through conducting and non-conducting states in repeated cycles. Each cycle includes a reset operation followed by an accumulation operation, creating a periodic pattern that allows the system to reset the conversion element multiple times without continuously exposing it to the conducting state. This periodic action reduces the total time the transistor remains conducting, minimizing signal charge loss while maintaining reset effectiveness.
2Loss of substance
If the time cycle of the reset operation is shortened to reduce signal charge loss, then image quality improves, but the capability to detect radiation irradiation is reduced
Solution Approach 1:
The patent performs multiple reset operations before the radiation irradiation detection phase. By completing several reset cycles in advance, the system ensures that the conversion element is thoroughly reset without needing to extend the conducting time period during the critical detection phase. This preliminary action allows the system to minimize signal charge loss during the actual irradiation detection while maintaining adequate reset efficiency.
Solution Approach 2:
The patent dynamically adjusts the conducting time period of the transistor based on the operational phase. During reset operations, the conducting time period is optimized for reset efficiency, while during radiation detection, the system transitions to a different timing pattern that prioritizes detection capability. This dynamic adjustment allows the system to optimize for different objectives at different times, resolving the contradiction between reset efficiency and detection capability.
3Reliability
If multiple reset operations are performed sequentially to ensure thorough resetting, then reset completeness improves, but the time required for reset operation increases
Solution Approach 1:
The patent implements periodic reset operations where multiple reset cycles are performed in a repeating pattern. Each cycle consists of a reset operation followed by an accumulation operation, creating a rhythmic sequence that efficiently resets the conversion element. The periodic structure allows the system to achieve thorough resetting through multiple cycles while maintaining a predictable and manageable time pattern, avoiding excessive time consumption.
Solution Approach 2:
The patent ensures continuous useful action by seamlessly transitioning between reset operations and accumulation operations. The system maintains a continuous operational flow where the transistor is cycled through conducting and non-conducting states without idle periods. This continuity allows multiple reset operations to be performed efficiently in sequence, achieving reset completeness without significant time loss, as the system is always performing a useful function.
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 approach allows for improved detection of radiation with longer irradiation times and reduces image artifacts by ensuring sufficient reset time while maintaining high-quality image acquisition.
Implementation Method 1
a plurality of conversion elements configured to convert radiation into an electric charge
Data Source
AI summary
A radiation imaging apparatus comprises a conversion element and a transistor. A drive unit performs a reset operation at a plurality of times, by supplying a conducting voltage to gates of the transistors, successively, one row by one row, an operation of stopping the supplying of the conducting voltage responsive to detecting the irradiation of the radiation to perform an accumulation operation and, after the reset operation, a read out operation. During the reset operation, a period between the supplying the conducting voltage to the gates of the transistors in one row and the supplying the conducting voltage subsequently to the gates of the transistors in another row is different from a period between the supplying the conducting voltage to the gates of the transistors in the another row and the supplying the conducting voltage subsequently to the gates of the transistors in further another row.