Radiation Imaging Pixel Crosstalk Reduction via Dual-Period Signal Readout
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Solution Overview
Problem
Radiation imaging apparatuses face a decrease in signal-to-noise ratio due to crosstalk caused by parasitic capacitances between column signal lines and conversion elements, which is not effectively addressed by conventional correlated double sampling techniques when reset operations differ between sampling instances.
Innovation Solution
A radiation imaging apparatus with a readout unit that includes a reset unit to reset the signal line potential, allowing for two distinct periods of signal readout: one with the switch off and one with the switch on, enabling the calculation of a difference between signals to reduce crosstalk components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional correlated double sampling is used to reduce noise, then KTC noise can be canceled under ideal conditions, but crosstalk from parasitic capacitances cannot be effectively removed when reset operations differ between sampling instances
Solution Approach 1:
The patent segments the signal reading process into two distinct periods: a first period for reading baseline signals (with switch off) and a second period for reading radiation signals (with switch on). By separating these readings and applying reset operations between them, the patent isolates crosstalk components that can then be subtracted to eliminate interference, thereby resolving the contradiction between noise reduction and crosstalk removal
Solution Approach 2:
The patent applies a reset operation to the signal line potential before both the first and second signal readings. This preliminary action ensures that any crosstalk-induced potential changes are captured in the first reading and can be subtracted from the second reading, effectively removing crosstalk interference while maintaining the noise cancellation benefits of correlated double sampling
2Stability of the object's composition
If reset operation is performed between first and second sampling instances, then signal line potential is stabilized, but noise component changes preventing effective noise cancellation
Solution Approach 1:
The patent converts the harmful effect of reset operations changing noise components into a beneficial measurement strategy. By deliberately performing reset operations between readings and capturing the resulting potential changes (including crosstalk) in the first reading, the patent enables subtraction of these changes from the second reading, thereby achieving both potential stability and effective interference removal
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 crosstalk interference, enhancing the accuracy of radiation detection and monitoring by isolating the net radiation component, thereby improving the signal-to-noise ratio and responsiveness of radiation sensing.
Implementation Method 1
a conversion element configured to convert radiation into an electric signal
Implementation Method 2
Parasitic capacitances are formed between a column signal line for reading out signals from conversion elements and the electrodes of the multiple conversion elements in the column in which the column signal line is arranged. The column signal line and the conversion elements are capacitively coupled due to these parasitic capacitances
Data Source
AI summary
A pixel includes a conversion element detecting radiation, and a switch between the element and a signal line. A readout unit reads out a signal on the signal line. The readout unit includes a reset unit that resets a potential of the signal line. A period during which the readout unit reads out a signal on the signal line includes a first period during which the signal line is reset, and a signal on the signal line in a state that the switch is not turned on is read out, and a second period during which the signal line is reset, and a signal on the signal line due to the switch being turned on is read out. The processing unit calculates a difference between the signals read out in the second and first periods.