Solid-State Imaging Device Signal Correction for Saturation
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Solution Overview
Problem
Conventional solid-state imaging devices face image quality degradation due to signal saturation when generating one image signal from plural photoelectric conversion elements, leading to reduced dynamic range and linearity issues.
Innovation Solution
A solid-state imaging device with a photoelectric conversion unit, read-out circuit unit, and signal processing unit that corrects signals from photoelectric conversion elements to maintain linearity by adjusting signal levels based on the change rate relative to light amount, preventing saturation and enhancing dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signals from multiple photoelectric conversion elements are combined to generate one image signal, then sensitivity is improved, but signal saturation occurs more easily causing image quality degradation
Solution Approach 1:
The patent implements dynamic signal correction where the signal processing unit adjusts the saturation signal level adaptively based on the actual signal values from multiple photoelectric conversion elements. The correction amount is calculated dynamically as the difference between the saturation signal level and the actual signal, allowing the system to maintain optimal performance across varying light conditions while preventing saturation artifacts.
Solution Approach 2:
The patent changes the parameter of saturation signal level from a fixed value to an adjustable value that can be modified through signal correction. By adding a correction amount to the saturation signal level based on the actual signal readings, the system effectively changes the operational parameter to prevent saturation while maintaining the benefits of combined signal processing.
2Productivity
If the potential barrier between photoelectric conversion elements is reduced to improve signal processing, then signal integration is enhanced, but the saturation signal level of each element decreases
Solution Approach 1:
The patent introduces a signal correction mechanism as an intermediary between the photoelectric conversion elements and the final image signal output. This intermediary process calculates the difference between the saturation signal level and actual signals, then adds appropriate correction amounts to maintain accurate signal levels while allowing the potential barrier to remain reduced for efficient signal integration.
Solution Approach 2:
The patent implements a feedback mechanism where the actual signal values from photoelectric conversion elements are continuously monitored and used to determine the correction amount. This feedback loop ensures that the saturation signal level is maintained accurately by adjusting the correction based on real-time signal conditions, preventing both saturation and loss of dynamic range.
3Reliability
If signal correction is applied to prevent saturation, then image quality is improved, but processing complexity increases
Solution Approach 1:
The patent segments the signal processing into distinct functional units: a signal acquisition unit that reads signals from photoelectric conversion elements, a correction amount calculation unit that determines the necessary adjustment, and a signal correction unit that applies the correction. This segmentation allows each unit to perform its function independently and efficiently, reducing overall processing complexity while maintaining image quality.
Solution Approach 2:
The signal processing system performs self-correction by automatically calculating and applying the necessary correction amounts based on its own internal measurements. The correction amount is derived from the difference between the saturation signal level and actual signals within the system, eliminating the need for external calibration or complex external processing while maintaining high image quality.
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
The solution effectively suppresses image quality degradation by improving linearity and dynamic range, particularly in bright portions of images, by correcting signal levels and preventing saturation in the imaging device.
Implementation Method 1
a photoelectric conversion unit including one microlens and a plurality of photoelectric conversion elements
Data Source
AI summary
A solid-state imaging device includes a photoelectric conversion unit including one microlens and a plurality of photoelectric conversion elements, a read-out circuit unit configured to read out a first signal based on charges accumulated by one of the photoelectric conversion elements and a second signal based on charges accumulated by another one of the photoelectric conversion elements, and a signal processing unit configured to, in a case where the first signal is larger than a predetermined saturation signal level and the second signal, correct the first signal to a predetermined signal level based on the second signal so that a change rate of a third signal obtained by adding the first and second signals relative to a light amount approximates to the change rate in a case where the first signal is smaller than the predetermined saturation signal level.