3T MOS Sensor Driving Method for High Frame Rate Image Quality
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Solution Overview
Problem
Existing solid-state imaging apparatuses with 3-transistor construction face limitations in adjusting accumulation time, especially when switching drive modes, leading to potential picture quality deterioration due to insufficient accumulation time during electronic zooming and increased frame rates.
Innovation Solution
A driving method that allows concurrent execution of read out and electronic shutter scans in different drive modes, ensuring overlapping of PD reset timing with read out operations to maintain consistent accumulation time across mode switches, thereby extending accumulation time and preventing image signal invalidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the scan of the reset row is started only after completion of the read out scan, then the electronic zoom magnification can be changed, but the range where the accumulation time can be adjusted is limited
Solution Approach 1:
The patent applies preliminary action by starting the reset row scan in advance during the read out row scan period. Specifically, the reset row scan is initiated at a timing that overlaps with the read out row scan, allowing the photodiode reset to occur before the read out scan completes. This preliminary reset action enables extended accumulation time while maintaining electronic zoom functionality.
2Productivity
If the frame rate rises, then the productivity increases, but the accumulation time becomes short
Solution Approach 1:
The patent resolves this contradiction by introducing a temporal dimension overlap between the reset row scan and read out row scan. Instead of sequential execution in a single time dimension, the patent utilizes overlapping time periods where both scans occur simultaneously. This dimensional change in timing arrangement allows extended accumulation time even at high frame rates by effectively utilizing the overlap period.
3Duration of action of moving object
If the scan of the reset row and the scan of the read out row are overlapped, then the accumulation time can be extended, but the electric potential corresponding to the reset electric potential appears in a vertical output line
Solution Approach 1:
The patent applies local quality by selectively controlling the reset operation in different row regions. The reset row scan is performed on specific rows while the read out row scan operates on other rows, allowing localized reset actions without interfering with the read out process. This spatial differentiation in scan regions enables overlap execution while preventing harmful electric potential appearance in the vertical output line.
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 enhances the flexibility of accumulation time even when drive modes are switched, ensuring consistent picture quality during electronic zooming and high frame rates by allowing the reset row scan to start during the read out row scan, thus preventing image signal invalidation.
Implementation Method 1
charges accumulated in a photodiode (PD)
Data Source
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AI summary
In an amplifying type MOS sensor having a 3-transistor construction, when a frame rate is raised, an accumulation time of a frame just after the switching of a drive mode becomes short. When a gain correction is made to compensate a lack of accumulation time, a deterioration in picture quality is caused. A read out scan and a reset scan are executed in parallel in the frame before the switching of the drive mode, thereby preventing that a time period for resetting a pixel is overlapped with a time period for holding a pixel signal into a holding unit.