Charge Sweeping Section for Residual Image Charge Management
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Solution Overview
Problem
Image quality degradation and sensitivity lowering due to residual image charges stored in the charge storage section during non-exposure periods in image pickup devices, leading to prolonged exposure time reduction and poor carrier transport performance.
Innovation Solution
An image pickup apparatus with a charge sweeping away section and an electrode potential fixing section that maintains the potential of the lower or upper electrode constant for a specified time period after exposure, using a reset transistor or differential amplifier to manage residual image charges, ensuring efficient discharge and preventing image quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the charge storage section stores charge generated in the photoelectric conversion element during exposure, then the sensitivity and resolution are improved, but residual image charges remain in the charge storage section during non-exposure periods causing image quality degradation
Solution Approach 1:
The patent applies preliminary action by performing a first reset operation immediately after exposure ends to clear the charge storage section before residual image charges can accumulate and cause degradation. This proactive reset prevents the harmful effect from developing
Solution Approach 2:
The patent implements periodic action by performing multiple reset operations at different time points: a first reset immediately after exposure and a second reset after a predetermined period. This periodic clearing strategy ensures residual image charges are removed at regular intervals, preventing accumulation while maintaining high sensitivity during exposure
2Use of energy by moving object
If the exposure time period is extended to capture more light, then the sensitivity is improved, but the carrier transport performance deteriorates due to residual image charges in the charge storage section
Solution Approach 1:
The patent performs a reset operation immediately after exposure ends as a preliminary action to clear the charge storage section. This ensures that when the next exposure begins, especially after extended periods, the charge storage section is clean and will not interfere with carrier transport performance
Solution Approach 2:
The patent implements periodic reset operations to clear residual image charges at regular intervals. This periodic maintenance of the charge storage section ensures carrier transport performance remains high even when extended exposure times are used to capture more light
3Measurement precision
If the charge storage section is reset frequently to remove residual image charges, then the image quality is maintained, but the exposure time period is reduced
Solution Approach 1:
The patent implements periodic reset operations at strategically chosen time points: immediately after exposure and after a predetermined period. This periodic strategy maintains image quality by removing residual image charges while minimizing the impact on exposure time, as resets occur only when necessary between exposures
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 image quality degradation and sensitivity lowering by effectively managing residual image charges, allowing for extended exposure times and improved carrier transport efficiency.
Implementation Method 1
photoelectric conversion layer for generating charges (electrons, holes) for light of B, G, and R are stacked in order from a light incidence face
Data Source
AI summary
A lower electrode, a photoelectric conversion layer, and an upper electrode are stacked in order above a semiconductor substrate, and a charge storage section that stores charge generated in the photoelectric conversion layer is connected to the lower electrode. The charge stored in the charge storage section is swept away by a charge sweeping away section for a given time from the endpoint of exposure. The given time is a time taken until the residual image charge existing in the photoelectric conversion layer at the exposure end point time is sufficiently discharged to the outside of the photoelectric conversion layer in a state in which the same bias as that at the exposure start time point is applied to the photoelectric conversion layer.