Radiation Image Pickup Signal Wire Cross Talk Reduction
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Solution Overview
Problem
Existing image-pickup apparatuses for radiography face significant cross talk issues due to capacitive coupling between data lines and electrodes, leading to degraded image quality, especially when the duration between radiation irradiation and the start of the reading operation is long, and existing solutions are inadequate in reducing cross talk during this period.
Innovation Solution
An image-pickup system with a control unit that senses the end of radiation irradiation and maintains the electrical connection between signal wires and a node at a specified potential until the start of the reading operation, reducing cross talk by minimizing the time the signal wire is not connected to a fixed potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the accumulation-operation period is extended to allow appropriate radiation dose, then radiation imaging quality improves, but the duration between end of irradiation and start of reading increases causing increased cross talk
Solution Approach 1:
The patent resolves this contradiction by dynamically changing the electrical state of the data line based on the imaging phase. During the extended accumulation period, the data line remains connected to allow proper charge accumulation for high-quality imaging. After irradiation ends, the data line is disconnected and floated, preventing cross talk even during the extended period between irradiation end and reading start. This dynamic state change allows both extended accumulation and cross talk reduction.
2Ease of operation
If the off-resistance of switching elements is small and leakage currents are high, then switching performance improves, but cross talk increases during the period between irradiation and reading
Solution Approach 1:
The patent applies the extraction principle by removing the data line from the fixed potential connection during the post-irradiation period. This extraction isolates the data line from the voltage source that would drive leakage currents through the switching elements. By taking out the connection to the fixed potential, the harmful effect of leakage currents causing cross talk is eliminated, while the switching elements can still maintain their performance characteristics.
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 effectively reduces cross talk, particularly when the off-resistance of switching elements is small and leakage currents are high, and the duration between radiation irradiation and the start of the reading operation is extended, thereby improving image quality.
Implementation Method 1
each of the pixels includes a conversion element converting a radiation into an electric charge
Implementation Method 2
One of the factors responsible for causing cross talk is capacitive coupling occurring between the data line and the electrode of the conversion element in each pixel
Data Source
AI summary
An image-pickup apparatus including a detector comprising a detecting unit and a reading circuit, the detecting unit including pixels, each of which including a conversion element, the reading circuit which includes a connecting unit that is electrically connected to a signal wire transferring an electric signal and that electrically connects the signal wire to a node, and which performs a reading operation to output the electric signal from the pixel. A control unit controls an operation of the reading circuit, and a sensing unit senses the end of radiation irradiation based on an output of the reading circuit, which is acquired during the period of an accumulation operation of the detector. The control unit starts establishing the electrical connection between the signal wire and the node through the connecting unit based on the sensed irradiation end, and retains the electrical connection until the start of the reading operation.