Global Shutter Imaging Device Pixel Circuit with Feedback Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing imaging devices using rolling shutter methods often produce distorted images of moving objects, suffer from brightness differences in flash photography, and capture multiple images of blinking objects due to varying exposure start and end times across pixel rows, necessitating a global shutter function where exposure timing is synchronized across all pixels.
Innovation Solution
The imaging device incorporates a photoelectric converter, a transfer transistor, a charge accumulation node, and signal detection transistors with feedback circuits that allow for parallel signal readout and reset, enabling global shutter operation by synchronizing the second reset transistor and transfer transistor timing across all pixels, while reducing noise through feedback and capacitor configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rolling shutter method is used, then device complexity is reduced, but image quality deteriorates due to distortion and brightness differences
Solution Approach 1:
The pixel array is divided into multiple banks, with each bank having independent photoelectric converters and readout circuits. This segmentation allows simultaneous exposure across all pixels (global shutter) while maintaining simpler individual circuit designs, resolving the contradiction between device complexity and image quality.
Solution Approach 2:
Transfer transistors are introduced as intermediary elements between photoelectric converters and floating diffusion regions. These transfer transistors enable global shutter operation by allowing simultaneous charge transfer from all pixels to their respective readout circuits, eliminating rolling shutter artifacts while maintaining circuit simplicity.
2Manufacturing precision
If global shutter function is implemented, then image quality improves, but device complexity increases due to additional transistors and circuits
Solution Approach 1:
Multiple photoelectric converters within each bank share common floating diffusion regions and readout circuits. This merging approach allows global shutter operation across all pixels while reducing the total number of independent readout circuits needed, thereby limiting the increase in device complexity.
Solution Approach 2:
The pixel array is organized into multiple banks arranged in a two-dimensional structure, where each bank processes a subset of pixels independently. This dimensional organization allows parallel global shutter operation while distributing circuit complexity across multiple simpler units rather than requiring a single complex readout circuit.
3Adaptability or versatility
If transfer transistor is added between photoelectric converter and floating diffusion region, then global shutter operation is enabled, but noise increases
Solution Approach 1:
The transfer transistor is designed to automatically transfer charge packets during the transfer period without requiring additional control signals for each pixel. This self-service mechanism reduces control complexity and minimizes the time the transfer transistor is active, thereby reducing noise generation while enabling global shutter operation.
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 improves frame rate by shortening non-exposure periods, reduces noise, and allows for flexible sensitivity modes, achieving high-quality imaging with synchronized exposure across all pixels.
Implementation Method 1
a photoelectric converter that converts incident light into an electric charge
Data Source
AI summary
An imaging device including a photoelectric converter that converts incident light into an electric charge; a transfer transistor; a first node coupled to the photoelectric converter via the transfer transistor; a first signal detection transistor having a gate coupled to the first node; a second signal detection transistor having a gate coupled to the photoelectric converter; a signal line coupled to one of a source and a drain of the first signal detection transistor; a first transistor coupled to the first node; and a second transistor coupled to the photoelectric converter, wherein one of the source and the drain of the first signal detection transistor is coupled to the first transistor, one of a source and a drain of the second signal detection transistor is coupled to the second transistor, and no transistor is coupled between the photoelectric converter and the gate of the second signal detection transistor.