Quad Color Filter Array Camera Sensor Phase Detection Autofocus
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Solution Overview
Problem
Existing camera sensors face challenges in achieving high-resolution phase detection autofocus and depth sensing while maintaining cost-effectiveness and image quality, particularly in low-light environments, due to the limitations of sparse phase detection pixels and dual pixel sensors.
Innovation Solution
A quad color filter array (QCFA) camera sensor configuration with a dense distribution of phase detection pixels, allowing for improved phase detection autofocus and depth sensing without the need for multiple photodiodes per pixel, and enabling monochrome imaging in low-light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sparse phase detection pixels are used in traditional camera sensors, then manufacturing cost is reduced, but phase detection precision and depth sensing capability deteriorate
Solution Approach 1:
The pixel array is segmented into distinct functional regions: phase detection pixels (PDAF pixels) and imaging pixels. Each region serves its specific purpose, allowing dense PDAF pixel distribution for precise autofocus while maintaining separate imaging pixels for quality image capture. This segmentation resolves the contradiction by enabling both high PDAF precision and cost-effective manufacturing through specialized pixel zones.
Solution Approach 2:
Different regions of the pixel array are assigned different functional qualities: PDAF pixels are optimized for phase detection with appropriate optical characteristics, while imaging pixels are optimized for image capture. This local differentiation allows dense PDAF pixel distribution in specific areas without compromising overall image quality, achieving both precision and cost-effectiveness.
2Measurement precision
If dual pixel sensors are used to achieve phase detection, then depth sensing capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges phase detection functionality and imaging functionality into a single integrated pixel array rather than using separate dual pixel sensors. PDAF pixels and imaging pixels coexist in the same sensor structure, eliminating the need for multiple photodiodes per pixel location. This merging reduces device complexity and manufacturing cost while maintaining depth sensing capability through the dense PDAF pixel distribution.
Solution Approach 2:
The pixel array serves multiple functions simultaneously: PDAF pixels perform phase detection for autofocus and depth sensing, while imaging pixels capture image data. Some pixels may even serve dual purposes under different operating conditions. This multi-functionality eliminates the need for dedicated dual pixel structures, reducing complexity while maintaining depth sensing capabilities.
3Measurement precision
If phase detection pixels are densely distributed, then phase detection precision is improved, but image quality in low-light conditions deteriorates
Solution Approach 1:
The sensor is segmented into PDAF pixels and imaging pixels, allowing dense PDAF pixel distribution for precise phase detection while maintaining sufficient imaging pixels for quality image capture. In low-light conditions, the imaging pixels can be optimized for sensitivity without compromising PDAF precision, as each region serves its primary function independently.
Solution Approach 2:
The system dynamically switches between PDAF mode and imaging mode depending on operational requirements. During autofocus operations, PDAF pixels are actively used for phase detection. During image capture, especially in low-light conditions, imaging pixels are optimized for sensitivity. This dynamic operation allows both dense PDAF distribution and high image quality to coexist.
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
The QCFA camera sensor achieves enhanced phase detection and depth sensing capabilities while reducing manufacturing costs and maintaining image quality, even in low-light environments, by utilizing a dense distribution of phase detection pixels and remosaicing techniques.
Implementation Method 1
Each first sub-tile includes the first PD pixel coupled to a first microlens shared with at least one other pixel of the tile and the first imaging pixel coupled to a second microlens different from the first microlens
Implementation Method 2
A color filter array (CFA) coupled to the camera sensor and including a plurality of red, blue, and green color filters
Data Source
AI summary
Examples of capturing and processing image data are described. A device may include a camera including a camera sensor that includes a plurality of tiles that each include four sub-tiles. The camera may also include a color filter array coupled to the camera sensor and including a plurality of red, blue, and green color filters. A first sub-tile of each tile may include a phase detection pixel coupled to a microlens shared with at least one other pixel of the tile and an imaging pixel not coupled to a second microlens different from the first microlens. The device may also include a processor coupled to the camera and configured to control one or more first exposure settings of the phase detection pixel and control one or more second exposure settings of the non-phase detection pixel. Control of the second exposure settings is independent from control of the first exposure settings.