Global Electronic Shutter Image Sensor Pixel Circuit
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Solution Overview
Problem
Conventional digital image sensors employ a rolling shutter mechanism, leading to artifacts such as distorted shapes of moving objects due to varying exposure times across rows, which affects picture quality.
Innovation Solution
Implementing a global electronic shutter in digital image sensors, where all rows have the same exposure time, achieved through the use of additional transistors and control signals to manage the photo-generated current, ensuring uniform integration time across the sensor array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a rolling shutter mechanism is used to simplify the sensor structure and reduce manufacturing complexity, then device complexity is reduced, but image quality deteriorates due to motion artifacts and distortion of moving objects
Solution Approach 1:
The patent replaces the mechanical rolling shutter with an electronic shutter implemented through pixel-level circuit control. Each pixel circuit independently controls the integration period start and end times using electronic signals, eliminating the need for mechanical moving parts while achieving global shutter functionality. This substitution resolves the contradiction by maintaining structural simplicity while improving image quality through electronic timing control.
Solution Approach 2:
The patent implements preliminary action by pre-synchronizing the integration period across all pixels before readout. The control circuit generates synchronized start and stop signals for the integration period across the entire sensor array, ensuring all pixels capture the same temporal window. This preliminary synchronization prevents motion artifacts and distortion while maintaining a simplified sensor structure without mechanical components.
2Manufacturing precision
If additional transistors are added to each pixel circuit to implement global electronic shutter control, then image quality improves by eliminating motion artifacts, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the additional transistors in the pixel circuit to serve multiple functions. The same transistors that control the integration period timing also participate in the standard pixel operations such as charge transfer and signal amplification. This multi-functionality reduces the net increase in device complexity while achieving global shutter functionality and improved image quality.
Solution Approach 2:
The patent merges the global shutter control functionality with the existing pixel circuit architecture. The additional transistors are integrated into the pixel circuit in such a way that their control lines are shared across the entire sensor array, allowing a single control signal to synchronize all pixels. This merging approach minimizes the increase in device complexity while achieving the desired image quality improvement.
3Ease of manufacture
If rolling shutter is used to reduce manufacturing complexity, then ease of manufacture is improved, but reliability of image capture deteriorates due to temporal distortion
Solution Approach 1:
The patent replaces the mechanical rolling shutter with an electronic shutter implemented through pixel-level circuit control. Each pixel circuit independently controls the integration period start and end times using electronic signals, eliminating the need for mechanical moving parts while achieving global shutter functionality. This substitution resolves the contradiction by maintaining structural simplicity while improving image quality through electronic timing control.
Solution Approach 2:
The patent implements feedback mechanisms through the control circuit that monitors and synchronizes the integration period across all pixels. The control circuit generates and distributes timing signals to ensure all pixels start and stop integration simultaneously, providing feedback-based synchronization that maintains reliable image capture while keeping the sensor structure simple and easy to manufacture.
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 solution eliminates motion artifacts and improves image quality by ensuring all pixels capture the image at the same time, resulting in a more accurate representation of moving objects without distortion.
Implementation Method 1
pixels accumulate an electronic signal that is in turn related to the photon signal impinging on that pixel during the integration, or exposure, period
Data Source
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AI summary
In various embodiments, an image sensor and related methods of operation of the image sensor are disclosed. In an embodiment, an image sensor includes at least one pixel. The at least one pixel including a transistor to couple an overflow capacitor to a floating diffusion node. Under a low light condition, photocharge is to be collected in a floating diffusion, but substantially not into an overflow node. Under a high light condition, photocharge is to overflow into the overflow node. Other sensors and related operations are disclosed.