Dual-Capacitor X-Ray Imaging for Low Noise and High Dynamic Range
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Solution Overview
Problem
Existing imaging devices face challenges in achieving low noise, high speed, and high dynamic range due to issues with integration capacitors being saturated at high doses, difficulty in handling sudden input signal variations, and restrictions on exposure time periods.
Innovation Solution
An imaging device with a conversion unit, multiple capacitors for charge accumulation, voltage conversion circuits, storage units, and transfer circuits to manage charge accumulation and output, along with mode selection and differential voltage processing to enhance dynamic range and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed capacitance integration capacitor is used, then the circuit structure is simple, but the capacitor becomes saturated at high doses and cannot correctly detect X-ray dose
Solution Approach 1:
The patent applies dynamics by making the integration capacitance variable rather than fixed. The capacitance value is dynamically adjusted based on the signal level: a first capacitance value is used when the signal is below a threshold, and a second capacitance value is used when the signal exceeds the threshold. This dynamic adjustment prevents saturation at high doses while maintaining sensitivity at low doses, resolving the contradiction between simple structure and measurement precision.
2Adaptability or versatility
If feedback capacitance is selected from current output value for next frame, then the system can adapt to signal variations, but it is difficult to cope with sudden variations in input signal
Solution Approach 1:
The patent applies preliminary action by pre-setting multiple capacitance values (first capacitance value and second capacitance value) that can be immediately switched based on signal threshold detection. Instead of calculating the next frame's capacitance from current output values, the system has capacitance values ready in advance that can be instantly selected when signal variations occur, enabling rapid response to sudden input signal changes while maintaining adaptability.
3Adaptability or versatility
If a selector switch for wide dynamic range is added, then the system can handle varying signal levels, but the circuit becomes saturated before switching and charge signal disappears
Solution Approach 1:
The patent applies feedback by continuously monitoring the signal level and using this information to control the capacitance value. When the signal exceeds a predetermined threshold, the system switches from the first capacitance value to the second capacitance value, and when the signal falls below the threshold, it switches back. This feedback mechanism ensures the circuit operates in the appropriate range without saturation, maintaining charge signal integrity while handling varying signal levels.
4Productivity
If exposure time period is restricted in one frame, then the integration capacitor can be properly managed, but the imaging speed is limited
Solution Approach 1:
The patent applies parameter changes by modifying the capacitance value parameter based on signal conditions. By switching between first capacitance value and second capacitance value according to whether the signal exceeds the threshold, the system can properly manage the integration capacitor across different signal levels without restricting the exposure time period, thereby maintaining high imaging speed while ensuring capacitor management stability.
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
The device achieves low noise, high speed, and expanded dynamic range by effectively managing charge accumulation and output, allowing accurate detection of X-rays across varying intensities.
Implementation Method 1
a conversion unit that converts an incident electromagnetic wave into a charge
Data Source
AI summary
Provided is an imaging device with low noise and a high dynamic range.An imaging device includes: a conversion unit that converts an incident electromagnetic wave into a charge; a first capacitor that accumulates the charge when a voltage corresponding to the charge is equal to or lower than a predetermined threshold; a second capacitor that accumulates the charge when the voltage exceeds the threshold; a voltage conversion circuit that converts the charges accumulated in the first capacitor and the second capacitor into voltages; a first storage unit that stores a voltage corresponding to the accumulated charge in the first capacitor after a lapse of a first period since the first capacitor has started accumulating the charge; and a second storage unit that stores a voltage corresponding to the accumulated charges in the first capacitor and the second capacitor after a lapse of a second period longer than the first period since the first capacitor has started accumulating the charge.