Image Pickup Apparatus Focus Detection Region Correction
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Solution Overview
Problem
Conventional image pickup apparatuses face challenges in accurately calculating defocus amounts due to changes in the center position of the focus detection region, leading to reduced focus detection accuracy, especially with highly-dense AF frames.
Innovation Solution
An image pickup apparatus that includes a selection unit to choose a focus detection region from multiple options and a calculation unit to compute defocus amounts using correction values specific to each region, allowing for precise defocus calculations by varying correction values based on different focus detection regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the accumulation region (focus detection region) of the AF sensor is changed to increase the number of focus detection regions, then the focus detection time can be reduced, but the center position of the focus detection region may be changed leading to reduced focus detection accuracy
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for each focus detection region before actual focus detection occurs. The correction values are computed based on the relationship between image shift amounts and defocus amounts for different region centers, and these pre-computed values are then retrieved during focus detection to ensure accuracy without adding real-time calculation overhead.
Solution Approach 2:
The patent changes parameters by introducing region-specific correction values that adjust the calculated defocus amount based on the center position of each focus detection region. Instead of using a single correction value for all regions, the system selects and applies appropriate correction values according to which region is being used, thereby compensating for center position variations and maintaining detection accuracy across multiple regions.
2Adaptability or versatility
If highly-dense AF frames over 40 points are set to increase focus detection coverage, then the detection coverage is improved, but the center position of the focus detection region changes frequently leading to reduced calculation accuracy
Solution Approach 1:
The patent applies segmentation by dividing the focus detection system into multiple independent focus detection regions, each with its own pre-calculated correction value. This allows the system to use highly-dense AF frames with multiple points while maintaining accuracy in each individual region through localized correction values that account for each region's specific center position characteristics.
Solution Approach 2:
The patent changes parameters by implementing a set of correction values corresponding to different focus detection regions. The system selects the appropriate correction value based on the active focus detection region, enabling accurate defocus calculation across extensively distributed AF frames with over 40 points while adapting to center position variations in each region.
3Adaptability or versatility
If the center position of the focus detection region is changed to adapt to different objects and lenses, then the adaptability is improved, but precise correction cannot be performed leading to reduced focus detection accuracy
Solution Approach 1:
The patent changes parameters by establishing a set of correction values that correspond to different focus detection region centers. When the center position changes to adapt to different objects and lenses, the system selects the appropriate correction value from the set, enabling precise correction for each region while maintaining adaptability across various shooting conditions.
Solution Approach 2:
The patent applies feedback by using pre-calculated correction values that compensate for center position variations. The correction values are determined based on the relationship between image shift amounts and defocus amounts for each region center, and this feedback mechanism ensures that accurate defocus calculations are performed regardless of which focus detection region is active.
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 enables high-accuracy defocus calculations, improving focus detection accuracy even when the focus detection region changes, ensuring precise focusing regardless of the imaging lens or object conditions.
Implementation Method 1
a light receiving element to photoelectrically convert an optical image to output a pair of image signals
Data Source
AI summary
An image pickup apparatus includes a light receiving element configured to photoelectrically convert an optical image to output a pair of image signals, a selection unit configured to select a focus detection region from among a plurality of focus detection regions, and a calculation unit configured to calculate a defocus amount based on the image signals from the selected focus detection region and a correction value for the selected focus detection region, and the correction value varies depending on the plurality of focus detection regions.