Image Sensor Readout Dynamics for Noise Uniformity
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Solution Overview
Problem
Existing imaging elements with micro lenses and photoelectric conversion units face noise signal differences when reading image signals from pixels using different methods, leading to prominent noise disparities between distance measurement and other regions, especially when the distance measurement region remains static across multiple frames.
Innovation Solution
The imaging element employs a first and second readout operation for pixels within the same distance measurement region, with the first readout operation reading signals from one pixel and the second readout operation reading signals from another pixel, and randomly or periodically changes the position of the first region between frames to minimize noise differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If image signals are read by different methods between distance measurement region pixels and other region pixels, then the reading time is shortened, but noise signal differences become prominent between regions
Solution Approach 1:
The patent applies dynamics by making the first region position variable rather than fixed. The first region that undergoes the first readout operation is dynamically changed between different pixel regions in different frames, while the distance measurement region remains fixed. This dynamic adjustment ensures that different regions are subjected to different readout operations in different frames, preventing consistent noise patterns from appearing in the same location across multiple frames, thereby reducing prominent noise signal differences.
Solution Approach 2:
The patent implements periodic action by alternating the position of the first region across multiple frames. The first region is periodically changed to different pixel regions in a systematic manner across frames, ensuring that the first readout operation is applied to different spatial locations over time. This periodic variation in region assignment prevents the accumulation of consistent noise artifacts in specific areas while maintaining the speed benefits of differentiated readout operations.
2Reliability
If the same distance measurement region is used across multiple frames, then distance measurement consistency is maintained, but noise signal differences between regions become more prominent
Solution Approach 1:
The patent resolves this contradiction by dynamically adjusting the first region position while keeping the distance measurement region fixed. The first region is changed to different pixel regions in different frames, ensuring that the noise-reducing first readout operation is applied to varying locations. This dynamic approach maintains distance measurement consistency (since the distance measurement region remains the same) while preventing prominent noise differences by varying which other regions receive the first readout operation.
3Productivity
If different readout operations are applied to different pixel regions, then processing efficiency is improved, but uniformity of noise levels across regions deteriorates
Solution Approach 1:
The patent maintains processing efficiency by continuing to apply different readout operations (first and second readout operations) to different pixel regions. However, it improves noise level uniformity by dynamically changing which regions receive the first readout operation across frames. This ensures that all regions are periodically subjected to both readout operation types, averaging out noise characteristics and achieving more uniform noise levels across the entire pixel array while preserving the speed benefits of differentiated processing.
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 reduces noise signal differences between regions, enhancing image quality by uniformly applying readout operations across the imaging element, even when capturing multiple frames with a static distance measurement region.
Implementation Method 1
a plurality of pixels with a plurality of photoelectric conversion units for one micro lens
Data Source
AI summary
An image capture apparatus includes an imaging element, first and second setting units, and a reading unit. The imaging element includes a plurality of pixels configured to have a plurality of photoelectric conversion units for one micro lens. The first setting unit sets a first region and a second region. The second setting unit sets a distance measurement region. The reading unit performs different readout operations in the first region and the second region. At the time of capturing images in a plurality of frames, when the second setting unit sets the same distance measurement region in the images in the plurality of frames, the first setting unit changes the position of the first region in the distance measurement region between the images in the plurality of frames at random or periodically.