Phase Difference Detection Area Division for Compact Camera Autofocus
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Solution Overview
Problem
Conventional phase difference auto focus methods in compact cameras with small solid state image capturing elements suffer from degraded precision due to small light shielding film apertures, leading to reduced in-focus position detection accuracy.
Innovation Solution
The implementation of a pair-pixel configuration with pupil-divided phase difference detection pixels on the light receiving surface, where the phase difference detection area is divided into multiple sub-areas based on the camera's settings to enhance precision and speed, calculating phase differences and controlling the focus lens accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the light shielding film aperture is reduced to enable phase difference detection in compact cameras with small solid state image capturing elements, then phase difference detection capability is achieved, but the precision of in-focus position detection is degraded
Solution Approach 1:
The phase difference detection area is divided into multiple sub-areas, and correlation calculations are performed separately for each sub-area. This segmentation allows the system to maintain high precision by processing smaller, more manageable regions independently, then combining the results to achieve overall high-precision focus detection despite the small aperture constraints of compact cameras.
Solution Approach 2:
Different processing strategies are applied to different regions of the phase difference detection area. By making the detection process adaptive to local characteristics through sub-area division and selective correlation calculation, the system optimizes precision for each region while maintaining overall detection accuracy despite the small light shielding film aperture.
2Speed
If the light receiving time is shortened to achieve high-speed phase difference information acquisition, then detection speed is improved, but the precision of phase difference information is degraded
Solution Approach 1:
The detection area is divided into multiple sub-areas with individual correlation calculations. This segmentation enables parallel processing of different regions, maintaining high detection speed while improving precision through multiple measurement points that can be aggregated to reduce noise and enhance accuracy even with short exposure times.
3Measurement precision
If the phase difference detection area is divided into multiple sub-areas for correlation calculation, then detection precision is improved, but processing complexity increases
Solution Approach 1:
The phase difference detection area is divided into multiple sub-areas, and correlation calculations are performed for each sub-area. This segmentation improves precision by allowing localized optimization and reducing the impact of noise in any single region. The modular approach to processing actually simplifies the overall system architecture by breaking down a complex full-area calculation into manageable independent units.
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-speed and high-precision auto focus performance equivalent to single lens reflex cameras, regardless of camera settings or subject conditions, by optimizing phase difference detection and focus control through adaptive division of the phase difference detection area.
Implementation Method 1
a pair-pixel configured by a first phase difference detection pixel and a second phase difference detection pixel that are pupil-divided is arranged two-dimensionally in a phase difference detection area
Implementation Method 2
a focus lens that is disposed at the front end of a light path of the image capturing element and forms an optical image which is in-focus on the subject on the light receiving surface
Implementation Method 3
a solid state image capturing element 21 placed at the back of the photographing lens (20)
Data Source
AI summary
It is provided an image capturing apparatus including a control unit that determines whether to set a division number to a first division number n or to a second division number m which is larger than n based on a setting status of an image capturing apparatus, calculating a divided area evaluation curve by calculating a correlation between first detection information and second detection information for each of divided areas formed by dividing a phase difference detection area into the n or the m, and acquires a defocus amount to drive and control a focus lens to the in-focus position from a total evaluation curve obtained by conducting a required calculation processing on the divided area evaluation curves of the plural divided areas.