Global Shutter Image Sensor Sub-Integration Timing Control
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Solution Overview
Problem
Global shutter mode image sensors face challenges in capturing high-quality images of fast-moving objects and high dynamic range (HDR) without image distortion, as they do not effectively manage integration times across rows.
Innovation Solution
The image sensor employs a pixel array with a timing generator and row driver that divides the integration period into multiple sub-integration periods, allowing for uniform exposure across all rows and enabling the accumulation and storage of photocharges, which are then processed to eliminate blur and enhance HDR capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If global shutter mode is used to eliminate image distortion, then image distortion is eliminated, but the ability to capture fast-moving objects without blur and achieve high dynamic range is compromised
Solution Approach 1:
The integration period is divided into multiple sub-integration periods (e.g., first sub-integration period and second sub-integration period). Different rows are assigned to different sub-integration periods, allowing simultaneous integration across all rows while capturing multiple exposure states. This segmentation enables both distortion-free imaging and enhanced image quality by preserving temporal information that can be used for de-blurring and HDR processing.
2Quantity of substance
If integration time is extended to capture more photocharges for HDR, then dynamic range is improved, but motion blur increases
Solution Approach 1:
The total integration time is segmented into multiple shorter sub-integration periods distributed across different rows. Each row integrates photocharges during its assigned sub-integration period, and rows are sequentially activated. This allows the total integration time to be extended for HDR while motion blur is minimized because each individual row's integration interval is shorter, and the segmentation enables temporal separation of integration events.
Solution Approach 2:
The patent implements periodic activation of different row groups during alternating sub-integration periods. Rows are periodically selected for integration in a systematic manner, creating a rhythmic pattern of photocharge accumulation across the pixel array. This periodic action enables extended total integration time while maintaining manageable individual exposure intervals, reducing motion blur through temporal distribution.
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 approach allows for clear, distortion-free images of moving objects and improved HDR representation by ensuring consistent exposure times across all rows, enhancing the quality of images captured in global shutter mode.
Implementation Method 1
The row driver may accumulate photocharges at the photo element during each of the at least two sub integration periods
Data Source
AI summary
An image sensor which operates in a global shutter mode is provided. The image sensor includes a pixel array comprising a plurality of pixels arranged in a plurality of rows and columns, a timing generator configured to generate row driver control signals which controls an integration period of a pixel of the plurality of pixels to include at least two sub integration periods, and a row driver configured to generate a plurality of row control signals which controls each of the rows in the pixel array based on the row driver control signals, wherein the timing generator is further configured to control a single image frame to include the integration period and a readout period of the pixel, based on the row driver control signals.