Shared Detection Transistor for Uniform Imaging Accuracy
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Solution Overview
Problem
Existing imaging systems using multiple light receiving devices suffer from varying detection accuracy due to errors in transistor threshold voltage properties, leading to inconsistent light sensitivity across unit devices.
Innovation Solution
The system employs a configuration where a second light receiving device is used in a light-blocking state and shared across multiple unit circuits, with a detection circuit generating a detection signal based on the potential difference between the first and second light receiving devices in a reverse bias state, utilizing a common transistor for differential amplification to ensure uniform detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an amplification transistor is formed with respect to each unit device, then the detection signal can be generated for each light receiving device, but the detection accuracy varies due to errors in threshold voltage of the transistor
Solution Approach 1:
The patent merges the detection function by using a single detection transistor shared among multiple unit devices instead of having separate amplification transistors for each unit device. This shared detection transistor eliminates the variation in threshold voltage that would occur with multiple individual transistors, thereby uniformizing the detection accuracy across all light receiving devices.
Solution Approach 2:
The detection transistor is designed to serve multiple unit devices simultaneously, performing the detection function universally across different columns. This multi-functional approach allows one transistor to replace multiple individual transistors, reducing the impact of manufacturing variations on detection accuracy.
2Measurement precision
If both first light receiving device and second light receiving device are provided with respect to each unit circuit, then detection can be performed, but the device complexity increases
Solution Approach 1:
The second light receiving device is designed to serve multiple unit circuits simultaneously as a common reference device. By making the second light receiving device universal across columns, the patent reduces the total number of components needed while maintaining detection accuracy through the differential measurement approach.
Solution Approach 2:
The patent segments the detection function by separating the light receiving devices into two functional groups: first light receiving devices that detect actual light signals for each unit circuit, and a single second light receiving device that provides a common reference signal. This segmentation allows for simplified circuitry while maintaining measurement precision.
3Reliability
If the second light receiving device is used in common with respect to the plurality of unit circuits, then the detection accuracy can be uniformized, but the detection speed may be reduced
Solution Approach 1:
The patent implements periodic switching of the second light receiving device between different columns through the column selection circuit. By alternately connecting the shared second light receiving device to different columns in a periodic manner, the system maintains uniform detection accuracy across all columns while achieving practical detection speeds through time-division multiplexing.
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 configuration enhances the detection accuracy and uniformity of light amounts across multiple light receiving devices, simplifies the signal output circuit, and allows for rapid detection while minimizing the impact of transistor property errors, even with high quantum efficiency photoelectric conversion layers that have significant dark current.
Implementation Method 1
Each of the plurality of unit devices includes a light receiving device that generates electric charge according to an amount of received light
Implementation Method 2
when the first light receiving device and the second light receiving device are in a reverse bias state between the first wire and the second wire
Data Source
AI summary
An imaging apparatus includes a plurality of unit circuits connected to a detection line, and a signal output circuit. Each of the plurality of unit circuits includes a light receiving device including an electrode connected to a wire and an electrode, and a transistor that controls electrical connection between the electrode and the detection line. The signal output circuit includes a light receiving device in a light-blocking state including an electrode connected to a wire and an electrode, and a detection circuit that outputs a detection signal according to a potential of a detection point between the electrode and the electrode when the light receiving device and the light receiving device are in a reverse bias state between the wire and the wire.