CMOS Rolling Shutter Global Image via Vertical Blanking Light
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Solution Overview
Problem
CMOS pixel arrays using electrical rolling shutters face image artifacts and distortions when moving relative to stationary objects due to sequential integration of rows, which existing technologies struggle to mitigate without increasing pixel size and manufacturing cost.
Innovation Solution
Implementing a method that uses strobed light during vertical blanking periods to synchronize the integration of all rows of pixels, effectively achieving global shutter-type images with a CMOS pixel array using an electrical rolling shutter, reducing image distortions caused by relative movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrical rolling shutter is used to control exposure of CMOS pixel array, then manufacturing cost and pixel size are reduced, but image artifacts and distortions occur when moving relative to stationary objects
Solution Approach 1:
The patent applies periodic action by using strobed light illumination that activates during the vertical blanking period between sequential row exposures. This periodic lighting synchronizes with the rolling shutter timing to create the appearance of simultaneous exposure across all rows, eliminating motion artifacts while maintaining the cost-effective rolling shutter architecture.
Solution Approach 2:
The strobed light acts as an intermediary element that coordinates between the rolling shutter mechanism and the object being imaged. By providing synchronized illumination during the vertical blanking period, the strobed light enables all pixels to capture light simultaneously despite the sequential row-by-row exposure method, thereby eliminating distortion without requiring a complex global shutter.
2Device complexity
If electrical rolling shutter is used to control exposure of CMOS pixel array, then device complexity is reduced, but image distortions occur due to sequential integration of rows
Solution Approach 1:
The strobed light provides periodic illumination that synchronizes with the rolling shutter's vertical blanking period. This timing coordination creates the effect of simultaneous exposure across all rows, eliminating the sequential integration distortion while maintaining the simple rolling shutter control mechanism without adding complex hardware.
3Manufacturing precision
If global shutter is implemented to eliminate image distortions, then image quality is improved, but manufacturing cost and pixel size increase
Solution Approach 1:
Instead of implementing a true global shutter that simultaneously exposes all pixels, the patent creates a visual copy or simulation of global shutter functionality. By using strobed light during the vertical blanking period, the system replicates the appearance and effect of simultaneous exposure without actually implementing the complex global shutter hardware, thereby maintaining lower manufacturing cost.
4Illumination intensity
If light is provided continuously during image acquisition, then illumination is sufficient, but light duration increases causing potential motion artifacts
Solution Approach 1:
The patent employs periodic light strobing that activates only during the vertical blanking period between sequential row exposures. This periodic illumination provides sufficient light for image acquisition while minimizing the total light exposure duration, thereby preventing motion artifacts that would occur with continuous illumination during the entire exposure sequence.
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 the acquisition of high-quality, undistorted global shutter-type video images by ensuring all rows of the CMOS pixel array integrate concurrently, reducing image artifacts and maintaining the advantages of electrical rolling shutters while avoiding the drawbacks of traditional global shutters.
Implementation Method 1
the photodiode PD is operable to generate charges (e.g., photogenerated electrons or holes) in response to such light
Data Source
AI summary
A CMOS pixel array is introduced into a dark environment to acquire video image frames. During a first frame, each row of pixels is sequentially reset, one row at a time, and then each row of pixels is sequentially read out, one row at a time. During a second frame, each row of pixels is sequentially reset, one row at a time, and then each row of pixels sequentially read out, one row at a time. A light source illuminates the dark environment during a vertical blanking period between the reading of the last row during the first frame and the reading of the first row during the second frame. The light source does not illuminate the dark environment between reading the first and last rows during the first frame nor between reading the first and last rows during the second frame.