Image Sensor Dual Mode Focusing for Low Light Speed
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Solution Overview
Problem
Image sensors with a 16M-4M structure face poor focusing speed in dark conditions, despite improved signal-noise ratio and noise performance in 4M mode.
Innovation Solution
The image sensor employs an array of photosensitive units with focusing and non-focusing units, utilizing different micro lenses to gather more light, and switches between two output modes based on ambient luminosity, performing focusing control by reading output values from divided photosensitive pixels to enhance focusing speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image sensor operates in 4M mode under dark condition, then the signal-noise ratio and noise performance are improved, but the focusing speed becomes poor
Solution Approach 1:
The pixel array is segmented into first pixel groups and second pixel groups, where first pixels in each group are used for focusing detection and second pixels are used for imaging. This segmentation allows the system to use only a subset of pixels for focusing in dark conditions, improving focusing speed while maintaining good signal-noise ratio.
Solution Approach 2:
Different regions of the pixel array are assigned different functions: first pixel groups are optimized for focusing detection with appropriate micro lens configurations, while second pixel groups are optimized for imaging. This local differentiation allows the focusing function to operate efficiently in dark conditions without compromising overall image quality.
2Measurement precision
If more pixels are used for focusing detection, then the focusing accuracy is improved, but the signal-noise ratio deteriorates in dark conditions
Solution Approach 1:
Instead of using all pixels for focusing detection, the patent uses only first pixel groups (a partial subset) for this purpose. This partial action provides sufficient focusing accuracy while leaving second pixel groups available for imaging, thereby maintaining good signal-noise ratio in dark conditions.
3Device complexity
If the image sensor uses a single output mode, then the device complexity is reduced, but the adaptability to different lighting conditions deteriorates
Solution Approach 1:
The image sensor dynamically switches between first output mode (4M mode with first pixel groups for focusing) and second output mode (16M mode with all pixels for imaging) based on ambient light conditions. This dynamic adaptation allows the system to optimize performance for different lighting scenarios without requiring complex hardware changes.
Solution Approach 2:
The pixel array is designed with multi-functionality: pixels can serve as first pixels for focusing detection or second pixels for imaging depending on the operating mode. This universal design allows a single hardware structure to adapt to different lighting conditions and functional requirements.
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 improves focusing speed and accuracy in low light environments while maintaining high signal-noise ratio, and switches to higher resolution modes in brighter conditions.
Implementation Method 1
utilizing different micro lenses to gather more light
Implementation Method 2
an image sensor with a 16M-4M structure... converts an image formed through an optical system to an electrical signal
Data Source
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AI summary
The present disclosure discloses an image sensor, an imaging method, an imaging device and an electronic device. The image sensor includes an array of photosensitive units, an array of filter units and an array of micro lenses, in which the array of photosensitive units includes focusing photosensitive units and non-focusing photosensitive units. With the image sensor, when a current ambient luminous intensity is smaller than a preset intensity, the image sensor generates an image with the first output mode, and when the current ambient luminous intensity is greater than the preset intensity, the image sensor generates an image with the second output mode. In addition, when the image sensor is used to focus, phase focusing may be performed according to output values of two parts of photosensitive pixels.