Solid-State Imaging Device Dynamic Threshold Signal Combination
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in maintaining linearity of output voltages for signals with different dynamic ranges, leading to variations among individual units and pixels, resulting in noise and image deterioration such as 'tone jump' due to low precision corrections.
Innovation Solution
A solid-state imaging device with a signal processing part that dynamically compares read-out signals to a threshold value, selects necessary signals for combination, and generates a combined signal with extended dynamic range by adjusting the threshold value, ensuring smooth switching and maintaining linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If signals with different dynamic ranges are combined using fixed threshold values, then the dynamic range is extended, but linearity is lost and tone jump occurs due to variations among individual units and pixels
Solution Approach 1:
The patent applies dynamics by making the threshold value adjustable rather than fixed. The signal processing part dynamically changes the threshold value based on comparison results between read-out signals, enabling smooth switching between signals with different dynamic ranges while maintaining linearity despite variations among individual units and pixels
Solution Approach 2:
The patent changes the parameter of the threshold value to resolve the contradiction. By dynamically adjusting the threshold value instead of using a fixed value, the system achieves both extended dynamic range and maintained linearity, preventing tone jump and image deterioration
2Quantity of substance
If digital correction is applied to equalize gains of signals with different dynamic ranges, then dynamic range is extended, but precision is reduced due to variations among individual units and pixels
Solution Approach 1:
The patent applies preliminary action by performing comparison and selection before final signal combination. The signal processing part compares read-out signals with dynamically adjusted threshold values and selects appropriate signals for combinational operation, preventing precision loss that would occur with post-hoc digital correction of variations
3Device complexity
If fixed threshold values are used for signal combination, then the processing is simple, but smooth switching cannot be achieved due to variations among individual units and pixels
Solution Approach 1:
The patent applies dynamics by implementing a signal processing part that dynamically adjusts threshold values based on comparison results. This dynamic adjustment ensures smooth switching between signals despite variations among individual units and pixels, while the overall processing remains integrated and efficient
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 allows for smooth signal combination, achieving higher dynamic range and image quality while reducing noise and image deterioration, even with variations among individual units and pixels.
Implementation Method 1
CMOS (complementary metal oxide semiconductor) image sensors have been put into practical use. A CMOS image sensor, for each pixel, has an FD amplifier having a photodiode (photoelectric conversion element)
Data Source
AI summary
A solid-state imaging device 10 capable of extending a dynamic range by combining a plurality of read-out signals has a signal processing part 710 which, when combining the plurality of read-out signals, selects at least one signal which becomes necessary for the combination in accordance with a result of a comparison between at least one read-out signal among the plurality of read-out signals (high conversion gain signal HCG, low conversion gain signal LCG) with a threshold value (Joint Thresh), applies the selected signal to the combinational processing, and thereby generates the combined signal extended in the dynamic range, and the signal processing part can dynamically change the threshold value. By this configuration, it is possible to smoothly switch a plurality of signals to be combined irrespective of variations in individual units etc., possible to realize a higher dynamic range while suppressing deterioration of images, and consequently possible to realize a higher quality of image.