Imaging System Parallel Pixel Reset for Mechanical Shutter Lag
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Solution Overview
Problem
Existing imaging systems face issues with image lag due to inadequate reset operations in pixel arrays, leading to suboptimal charge accumulation and image quality, particularly when using mechanical shutters with shorter exposure times.
Innovation Solution
An imaging system with a mechanical shutter and a vertical scanning unit that executes parallel and sequential reset operations across adjacent rows of a pixel array, ensuring equal charge accumulation times and complete reset operations before light shielding, thereby reducing image lag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the reset operation of pixels on one row starts a predetermined period after the completion of the reset operation of pixels on another row, then the period from the start to completion of the reset operation shortens, but charges accumulated in pixels may not be able to be adequately reset and image lag appears
Solution Approach 1:
The pixel array is divided into multiple rows, and the reset operation is segmented to be performed sequentially across different rows. The vertical scanning unit controls the reset signal to be applied to different rows at different times, allowing the reset operation to be completed for one row before starting the next row, thus ensuring adequate reset time for each row while maintaining overall efficiency
Solution Approach 2:
The reset operation for subsequent rows is delayed until the reset operation of the previous row is completed. This preliminary completion approach ensures that each row receives sufficient reset time before the next row begins its reset cycle, preventing charge accumulation issues and image lag while maintaining a structured sequential operation pattern
2Productivity
If the Kth row selection period is set shorter to match the mechanical shutter traveling pattern, then the reset operation period shortens, but the charge accumulation may not be adequately reset
Solution Approach 1:
The row selection period is dynamically adjusted based on the mechanical shutter traveling pattern. The vertical scanning unit adapts the timing of reset operations to match the variable speed characteristics of the mechanical shutter, allowing shorter periods when the shutter moves faster and longer periods when it moves slower, thus maintaining both productivity and reset completeness
Solution Approach 2:
The selection period parameter is changed to be shorter than that for general electronic shutters, specifically optimized for mechanical shutter characteristics. This parameter adjustment allows the system to match the mechanical shutter's traveling pattern while ensuring adequate reset time through the sequential row operation control
Data Source
AI summary
An imaging system includes an image sensor and a mechanical shutter which controls the termination of exposure of the image sensor. The image sensor includes a pixel array in which a plurality of pixels are arrayed in a matrix, and a vertical scanning unit which scans the pixel array for each row. The vertical scanning unit parallelly executes some of the reset operations of pixels on at least two adjacent rows of the pixel array. The charge accumulation operation of pixels starts upon completion of the reset operation and terminates in response to light shielding by the mechanical shutter.