CCD Shift Register Residual Charge Drainage Method
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Solution Overview
Problem
Residual non-image charge in CCD shift registers after reset operations leads to inaccurate image representation due to manufacturing defects such as misalignment and defects in the semiconductor substrate, causing incomplete transfer of non-image charges to the reset drain.
Innovation Solution
A method where residual non-image charge is shifted to an adjacent charge storage region and the CCD shift register is reset multiple times, using a timing generator to generate clocking and reset signals, allowing charge to be shifted forward or backward within the CCD, ensuring complete drainage to the reset drain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single reset operation is performed to drain charge from CCD shift registers, then the reset operation is simple and fast, but residual non-image charge remains in charge storage regions due to manufacturing defects
Solution Approach 1:
The patent applies preliminary action by performing a first reset operation before image capture to drain non-image charge, then identifying and addressing residual charge in specific charge storage regions through additional targeted reset operations. This preliminary draining approach ensures that manufacturing defects do not compromise the completeness of charge removal, thereby improving reliability without excessive complexity.
Solution Approach 2:
The patent implements periodic action by performing multiple reset operations at different times: a first reset operation before image capture, and additional reset operations for charge storage regions where residual charge is detected. This periodic resetting ensures thorough drainage of non-image charge while managing the complexity through selective, time-staggered operations rather than continuous complex processing.
2Measurement precision
If multiple reset operations are performed to remove residual charge, then image accuracy is improved, but the time required for reset operations increases
Solution Approach 1:
The patent applies local quality by performing additional reset operations only on specific charge storage regions where residual non-image charge is detected, rather than resetting all regions uniformly. This localized approach improves image representation accuracy by addressing problem areas while minimizing unnecessary reset operations in regions that are already properly drained, thereby reducing overall reset time.
Solution Approach 2:
The patent implements partial action by performing reset operations on only those charge storage regions that require it, based on detection of residual charge. This selective partial resetting achieves the necessary image accuracy by addressing only the deficient regions, avoiding the time cost of uniformly resetting all charge storage regions multiple times.
3Productivity
If residual non-image charge remains in charge storage regions, then the CCD operation is simple and fast, but the image sensor does not produce accurate representation of captured image
Solution Approach 1:
The patent applies preliminary action by performing reset operations to drain non-image charge before image capture begins. This preliminary charge removal ensures that when the CCD operates at full speed during image capture, the charge storage regions are ready to accept only image-related charge, thereby maintaining both productivity and measurement precision without requiring slow continuous resetting during operation.
Solution Approach 2:
The patent implements local quality by performing additional targeted reset operations on specific charge storage regions where residual charge affects image accuracy. This localized correction maintains overall CCD operation speed by avoiding global resets, while selectively improving measurement precision in affected regions through focused intervention.
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 process effectively removes residual non-image charges, ensuring accurate image representation by repeatedly shifting and resetting charges, thereby improving the image sensor's output quality.
Implementation Method 1
charge-coupled device (CCD) shift registers
Implementation Method 2
transfer from charge storage regions 202, 204, 206, 208, 210 to a reset drain
Data Source
AI summary
One or more charge storage regions in a charge-coupled device (CCD) shift register can contain residual charge that did not transfer to a reset drain during a reset operation. An image sensor drains the residual charge from each charge storage region by shifting the residual charge to an adjacent charge storage region and resetting the CCD shift register one more time. The process of resetting the CCD shift register, shifting the residual non-image charge to an adjacent charge storage region, and resetting the CCD shift register again can be repeated any number of times.