Image Sensor Pixel Segmentation for Wide Dynamic Range Focus Detection
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Solution Overview
Problem
Existing digital image sensors face challenges in implementing a wide dynamic range (WDR) function while maintaining accurate focus detection, particularly in varying light conditions, as they struggle to efficiently utilize pixels with lower light-receiving efficiency for focus detection and exposure adjustments.
Innovation Solution
The digital image sensor employs a configuration where pixels are classified into higher-exposure and lower-exposure groups, with lower-efficiency pixels using longer exposure times and phase separation structures to detect focus information, and dynamically adjusts exposure settings based on light conditions to enhance focus detection accuracy across different regions of an image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixels are used for both WDR function and focus detection, then the sensor can capture wide dynamic range images, but the focus detection accuracy deteriorates due to insufficient light reaching lower-efficiency pixels
Solution Approach 1:
The pixel array is divided into first pixels and second pixels with different exposure efficiency. Second pixels are specifically designated for focus detection and are configured to operate during the first exposure period with longer exposure time, while first pixels handle general image capture. This segmentation allows optimized light utilization for each function.
Solution Approach 2:
The sensor dynamically adjusts exposure periods for different pixel groups. The first pixels undergo a first photoelectric conversion process during a first exposure period, while second pixels undergo a second photoelectric conversion process during a second exposure period that is longer than the first. This dynamic timing adjustment ensures sufficient light accumulation for focus detection pixels.
2Measurement precision
If lower-efficiency pixels are used for focus detection with longer exposure times, then focus detection accuracy improves, but the overall image capture efficiency deteriorates due to extended exposure periods
Solution Approach 1:
The pixel array is divided into first pixels and second pixels with different exposure efficiency. Second pixels are specifically designated for focus detection and are configured to operate during the first exposure period with longer exposure time, while first pixels handle general image capture. This segmentation allows optimized light utilization for each function.
Solution Approach 2:
While second pixels are undergoing the second photoelectric conversion process during the second exposure period, the first pixels simultaneously undergo the first photoelectric conversion process during the first exposure period. This continuous parallel operation ensures that focus detection and general image capture occur concurrently without sequential delays, maintaining high image capture efficiency.
3Manufacturing precision
If all pixels are configured for high exposure efficiency, then image capture quality improves, but the ability to detect focus information in lower light conditions deteriorates
Solution Approach 1:
Different regions of the pixel array are assigned different functional qualities. Second pixels specifically configured for focus detection have optimized characteristics for light accumulation and focus information extraction, while first pixels are optimized for general image capture quality. This local differentiation ensures each pixel group excels at its designated function.
Solution Approach 2:
The sensor dynamically adjusts exposure periods for different pixel groups. The first pixels undergo a first photoelectric conversion process during a first exposure period, while second pixels undergo a second photoelectric conversion process during a second exposure period that is longer than the first. This dynamic timing adjustment ensures sufficient light accumulation for focus detection pixels.
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 more accurate focus detection and improved image quality by ensuring that lower-efficiency pixels acquire necessary image information, even in conditions with insufficient light, thereby enhancing the WDR function and overall performance of the image sensor.
Implementation Method 1
an electronic sensor, for example, an image sensor
Data Source
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Figure 3
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AI summary
An electronic sensor and a method for controlling the electronic sensor are provided. The electronic sensor includes at least two pixels having different light-receiving efficiencies and at least two pixel groups having different exposure settings. At least one of the at least two pixels corresponds to at least one of the at least two pixel groups.