Photoelectric Conversion Device Dynamic Barrier Control
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Solution Overview
Problem
Photoelectric conversion devices face challenges in preventing charge leakage into holding portions while maintaining saturation charge amounts, leading to reduced dynamic range and noise interference.
Innovation Solution
A photoelectric conversion device with a control unit that adjusts the potential barrier of the third transfer unit during the exposure period, allowing for increased saturation charge accumulation without leakage, by changing the potential barrier from a first level to a second level higher than the first level, and using an amplifier circuit with selectable gains to manage signal charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the potential barrier of the third transfer switch is set lower to prevent charge leakage, then charge leakage is prevented, but the saturation charge amount decreases resulting in narrower dynamic range
Solution Approach 1:
The patent applies the dynamics principle by making the potential barrier of the third transfer switch variable rather than fixed. The control unit dynamically adjusts the potential barrier level based on the accumulation state of signal charges in the photoelectric converter. When signal charges approach saturation, the potential barrier is raised to prevent leakage; when signal charges are low, the potential barrier is lowered to allow efficient charge drainage. This dynamic adjustment resolves the contradiction between preventing charge leakage and maintaining saturation charge amount.
2Quantity of substance
If the potential barrier of the third transfer switch is set higher to increase saturation charge amount, then the saturation charge amount increases, but leakage of charges into the first holding portion occurs causing noise
Solution Approach 1:
The patent applies the parameter changes principle by modifying the potential barrier parameter of the third transfer switch based on the signal charge accumulation level. The control unit monitors the charge accumulation state and adjusts the potential barrier height accordingly. This parameter adjustment allows the system to maintain high saturation charge amounts when needed while preventing charge leakage noise when signal charges are sufficient, thus resolving the contradiction between these two parameters.
3Reliability
If the potential barrier is dynamically adjusted during exposure period, then both charge leakage is prevented and saturation charge amount is maintained, but device complexity increases
Solution Approach 1:
The patent applies the feedback principle by implementing a control unit that monitors the charge accumulation state in the photoelectric converter and provides feedback to adjust the potential barrier of the third transfer switch. This feedback mechanism ensures that the potential barrier is adjusted only when necessary, maintaining signal accuracy while avoiding unnecessary complexity. The control unit compares the current charge level with the saturation level and adjusts the potential barrier accordingly, creating a simple yet effective closed-loop control system.
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
Prevents false signals due to charge leakage while maintaining high saturation charge amounts, ensuring a wider dynamic range and reducing noise interference.
Implementation Method 1
a photoelectric converter that generates charges by photoelectric conversion
Data Source
AI summary
A photoelectric conversion device includes a plurality of pixels each of which includes a photoelectric converter that generates charges by photoelectric conversion, a first transfer unit that transfers charges in the photoelectric converter to a first holding portion, a second transfer unit that transfers charges in the first holding portion to a second holding portion, an amplifier unit that outputs a signal based on charges held in the second holding portion, and a third transfer unit that transfers charges of the photoelectric converter to a drain portion; and a control unit that, in an exposure period in which signal charges are accumulated in the photoelectric converter, changes a potential barrier formed by the third transfer unit with respect to the signal charges accumulated in the photoelectric converter from a first level to a second level that is higher than the first level.