Phase Difference AF Pixel Array Segmentation for Low Contrast Precision
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Solution Overview
Problem
Existing phase difference AF methods in imaging devices face challenges with low contrast subjects, where broadening the phase difference detecting region increases signal usage but lowers precision and slows down the focus detection process.
Innovation Solution
An imaging device with pairs of first and second pixel cells that calculate defocus amounts using narrow and broad range signal groups, generating a broad pitch signal group for precise and fast phase difference AF by controlling the focus state of the imaging optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the region for phase difference detection is broadened to improve detection precision for low contrast subjects, then detection precision is improved, but the time required for correlation operation increases
Solution Approach 1:
The patent divides the phase difference detection region into multiple sub-regions and performs correlation operations on each sub-region separately. This segmentation allows the system to process only relevant portions of the image, reducing the overall processing time while maintaining detection precision through the combined results from multiple sub-regions.
Solution Approach 2:
The patent applies different processing strategies to different regions of the image based on their local characteristics. By identifying regions with sufficient contrast and prioritizing correlation operations in those areas, the system achieves efficient processing that balances detection precision with reduced time requirements.
2Measurement precision
If all signals from the broadened region are used for correlation operation to improve detection precision, then detection precision is improved, but the processing speed decreases
Solution Approach 1:
The patent performs correlation operations on selected sub-regions rather than processing all signals from the entire broadened region. This partial action approach maintains detection precision by focusing on the most informative regions while significantly improving processing speed by avoiding unnecessary computations in low-contrast or redundant areas.
Solution Approach 2:
The patent extracts and processes only the essential signal components from the broadened detection region. By identifying and prioritizing signals from regions with sufficient contrast and removing or skipping processing of signals from low-contrast regions, the system achieves both high detection precision and fast processing speed.
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
Enables high-precision and high-speed phase difference AF, even with low contrast subjects, by efficiently utilizing all signals for correlation operations and reducing processing time.
Implementation Method 1
a solid-state imaging element such as a charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor
Data Source
AI summary
When reliability of a defocus amount which is calculated using a signal from a region 50A is low, a digital camera expands the phase difference detection target region to the regions 50A, 50B, and 50C. Further, the digital camera calculates a defocus amount using a correlation operation result of an output signal group of pixel cells 31R in an odd numbered column and an output signal group of the pixel cells 31L in an odd numbered column and a correlation operation result of an output signal group of pixel cells 31R in an even numbered column and an output signal group of the pixel cells 31L in an even numbered column, in the regions 50A, 50B, and 50C.