Disparity-Preserving Binning for Phase Detection Autofocus
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Solution Overview
Problem
Conventional phase detection autofocus (PDAF) systems in digital imaging face challenges in balancing the number of PDAF pixels with hardware costs, processing times, imaging resolution, and low-light focusing effectiveness, while traditional binning methods often compromise disparity information.
Innovation Solution
The implementation of disparity-preserving binning techniques across an imaging sensor array, where PDAF pixels and imaging pixels are consistently binned in a parallel readout, preserving horizontal disparity information through vertical binning of PDAF pixels and diagonal binning of imaging pixels, using pixel actuators and disparity-inducing structures like metal shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of PDAF sensors is increased to provide higher data resolution for more accurate autofocusing, then measurement precision is improved, but hardware cost increases
Solution Approach 1:
The patent combines PDAF pixels and imaging pixels into the same sensor array, allowing dual functionality. PDAF pixels are integrated within the imaging sensor grid, enabling both phase detection autofocus and imaging functions using shared hardware resources, thereby reducing the need for separate dedicated PDAF sensors
Solution Approach 2:
The sensor array is designed so that pixels can serve multiple functions. The same pixel array used for imaging also performs PDAF measurements by utilizing disparity-inducing structures (such as microlens arrays or beam splitters) that direct light from different focal planes to different pixels within the array, enabling one hardware component to fulfill multiple roles
2Measurement precision
If the number of PDAF sensors is increased to provide higher data resolution, then measurement precision is improved, but processing time increases
Solution Approach 1:
By merging PDAF and imaging functions into a single parallel readout system, the patent enables simultaneous capture of both PDAF disparity information and imaging data. This integration allows the system to process autofocus measurements and image data concurrently through shared readout circuitry, reducing overall processing time compared to sequential processing of separate sensor arrays
Solution Approach 2:
The consistently binned parallel readout architecture enables continuous operation where PDAF measurements and imaging occur simultaneously without interruption. The system maintains uninterrupted data flow from the sensor array, allowing autofocus processing to proceed continuously alongside image capture, thereby minimizing processing delays
3Manufacturing precision
If traditional binning methods are applied to PDAF pixels, then imaging resolution is improved, but disparity information is lost
Solution Approach 1:
The patent applies different binning strategies to different pixel types within the same array. PDAF pixels utilize vertical binning that preserves horizontal disparity information, while imaging pixels can employ diagonal or other binning patterns optimized for image quality. This localized differentiation ensures that each pixel type's binning operation is optimized for its specific function without compromising the other
Solution Approach 2:
The sensor array is segmented into distinct PDAF pixel regions and imaging pixel regions, each with dedicated readout paths and binning configurations. This segmentation allows independent optimization of binning operations for each function, enabling imaging pixels to be binned for resolution enhancement while PDAF pixels maintain their disparity information through separate, preserved readout channels
4Measurement precision
If the number of PDAF sensors is increased, then measurement precision is improved, but low-light focusing effectiveness decreases
Solution Approach 1:
By merging PDAF and imaging functions into a single sensor array with shared photodetectors, the system maximizes light utilization. The same photodetectors that capture imaging photons also detect PDAF disparity information, eliminating the need for separate dedicated PDAF sensors that would further reduce light availability. This consolidation ensures optimal light gathering efficiency for both functions
Solution Approach 2:
The integrated sensor array enables each pixel to contribute to both imaging and autofocus functions simultaneously. During low-light conditions, the system can leverage the combined signal from all pixels for imaging while extracting PDAF measurements from the same data, rather than requiring additional dedicated PDAF sensors that would compete for limited photons, thereby maintaining low-light focusing effectiveness
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 enhances autofocus speed and accuracy by maintaining disparity information, reducing hardware costs, and improving low-light performance without compromising imaging resolution.
Implementation Method 1
The pixel actuators are each coupled with a respective one of the PDAF pixels and a respective subset of the imaging pixels. The controller is to selectively actuate the pixel actuators to perform consistently binned parallel readout
Implementation Method 2
The pixel block has an array of photodetector elements including at least one square array of PDAF pixels interspersed with a plurality of imaging pixels
Implementation Method 3
disparity-inducing structures are configured to position same-disparity PDAF pixels to be binned together in accordance with consistently applied control of the pixel actuators (e.g., by using diagonally placed metal shielding)
Data Source
AI summary
Techniques are described for disparity-preserving pixel binning during consistently binned parallel readout of an imaging sensor array having both phase detection autofocus (PDAF) pixels and imaging pixels. Each group of PDAF pixels and each group of imaging pixels is coupled with pixel actuators according to an particular arrangement, so that consistently applied control of the pixel actuators results in desired binning of both the PDAF pixels and the imaging pixels. According to some implementations, though such control of the pixel actuators is consistently applied across the pixels of the array, parallel readout of the sensor array yields diagonally binned imaging pixels, but vertically binned PDAF pixels to preserve horizontal PDAF disparity information. Additionally or alternatively, disparity-inducing structures are configured to position same-disparity PDAF pixels so that consistently applied control of the pixel actuators preserves disparity information during binning.