Image Sensor Signal Separation via Multi-Node Threshold Control
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Solution Overview
Problem
Existing image sensors, such as CMOS sensors, face challenges in separating common mode offsets like dark current and noise from effective signals, resulting in a poor signal-to-noise ratio and inability to meet requirements for long distance ranging, high precision imaging, and high frame rate imaging.
Innovation Solution
A signal separation method involving determining and controlling threshold voltages between primary nodes to transfer echo radiation charges to subsequent-stage nodes while keeping background radiation charges in primary nodes, thereby isolating and separating background radiation from echo radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing image sensors are used to receive radiation signals, then the sensor can detect radiation, but the common mode offsets (dark current and noise) cannot be separated from effective signals, resulting in poor signal-to-noise ratio
Solution Approach 1:
The patent divides the charge storage and processing into multiple separate nodes (first node, second node, third node) with different threshold voltages. This segmentation allows different types of charges (background radiation charges, echo radiation charges, and offset charges) to be selectively transferred and separated across nodes, enabling the removal of common mode offsets while preserving effective signals.
Solution Approach 2:
Different nodes are assigned different threshold voltages tailored to their specific functions. The first node has a first threshold voltage for storing background radiation charges, the second node has a second threshold voltage for echo radiation charges, and the third node has a third threshold voltage for offset charges. This local differentiation of threshold voltages enables selective charge transfer and separation.
2Reliability
If existing image sensors are used for long distance ranging, then the sensor can detect reflected radiation, but the sensitivity is insufficient due to inability to separate common mode offsets from effective signals
Solution Approach 1:
The multi-node structure with different threshold voltages segments the charge processing path, allowing weak echo radiation charges to be selectively transferred from the second node to the third node while background radiation charges remain at the first node. This segmentation enhances sensitivity for long distance ranging by isolating weak signals from dominant offset signals.
Solution Approach 2:
The patent dynamically adjusts threshold voltages (first threshold voltage, second threshold voltage, third threshold voltage) to optimize charge transfer. By changing these voltage parameters, the system can adapt to different ranging distances and signal strengths, improving sensitivity for long distance applications while maintaining reliability.
3Measurement precision
If existing image sensors are used for high precision ranging, then the sensor can measure distance, but the output signal quality is poor due to unseparated common mode offsets
Solution Approach 1:
The patent implements a segmented charge transfer system where echo radiation charges are separated from background radiation charges and offset charges through multiple nodes with different threshold voltages. This segmentation produces high-quality output signals suitable for precise ranging measurements by eliminating contamination from common mode offsets.
Solution Approach 2:
Each node is optimized with specific threshold voltages for its intended function. The third node, in particular, uses a third threshold voltage that is lower than the first and second threshold voltages, enabling it to selectively remove offset charges while preserving echo radiation charges, thus improving output signal quality for high precision ranging.
4Productivity
If existing image sensors are used for high frame rate imaging, then the sensor can capture images quickly, but the signal-to-noise ratio remains poor due to inability to separate common mode offsets
Solution Approach 1:
The patent implements a segmented charge processing architecture that operates parallel to the image capture process. The multi-node structure with different threshold voltages processes offset charges separately from signal charges, enabling high frame rate imaging while maintaining high signal-to-noise ratio through effective offset separation.
Solution Approach 2:
The system performs preliminary charge separation at the node level before final signal output. By pre-separating common mode offsets from effective signals through the multi-node threshold voltage mechanism, the system prepares clean signals for high frame rate imaging without compromising signal quality.
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 method improves the signal-to-noise ratio and output signal quality, enabling image sensors to meet requirements for long distance and high precision ranging, high dynamic imaging, and high frame rate applications by effectively suppressing background radiation interference.
Implementation Method 1
controlling, when a second primary node of the at least two primary nodes that stores second radiation charges is electrically connected with an adjacent subsequent-stage node, a second threshold voltage between the second primary node and the adjacent subsequent-stage node so that echo radiation charges in the second radiation charges are transferred to the subsequent-stage node
Implementation Method 2
a photosensitive unit, configured to receive a first radiation to generate background radiation charges and receive a second radiation to generate background radiation charges and echo radiation charges
Data Source
AI summary
A signal separation method, a pixel unit, and a pixel array are provided. The method comprises: determining a first threshold voltage between a first primary node of at least two primary nodes that stores first radiation charges and an adjacent subsequent-stage and controlling, when a second primary node of the at least two primary nodes that stores second radiation charges is electrically connected with an adjacent subsequent-stage node, a second threshold voltage between the second primary node and the adjacent subsequent-stage node so that echo radiation charges in the second radiation charges are transferred to the subsequent-stage The second threshold voltage is equal to the first threshold voltage; the first threshold voltage is used to make the background radiation charges included in the first radiation charges fully or partially remain in the first primary node when the first primary node is electrically connected with the subsequent-stage node.