Imaging Apparatus Autofocus Selection Mechanism
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Solution Overview
Problem
Cameras with contrast detection autofocus systems face challenges in maintaining focus on moving subjects across wide areas, leading to potential misfocus on unintended subjects due to the combination of dedicated phase difference and phase difference detecting modules.
Innovation Solution
An imaging apparatus with multiple focus detection units, including a dedicated phase difference sensor and an image-plane AF sensor, selects the appropriate defocusing amount for focus control, ensuring accurate focus on the target subject by utilizing a defocusing amount selection and correction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If both a dedicated phase difference detecting module and a phase difference detecting image sensor are mounted to support wide detection areas, then the coverage area for autofocus is improved, but the reliability of focus tracking on target subjects deteriorates due to potential misfocus on unintended subjects
Solution Approach 1:
The patent divides the autofocus detection function into two separate modules: a dedicated phase difference detecting module for high-precision focus detection in specific areas, and a phase difference detecting image sensor for broader area coverage. By segmenting the detection responsibilities and using a selection unit to choose which module's data to trust, the system maintains wide coverage while ensuring reliable focus tracking through selective data validation.
2Device complexity
If a contrast detection autofocus system is used in compact and mirrorless cameras, then the device complexity is reduced, but the speed of autofocus deteriorates
Solution Approach 1:
The patent merges two autofocus detection methods into a single system: contrast detection (providing wide area coverage with simpler hardware) and phase difference detection (providing faster focus speed). The image sensor serves dual purposes as both the primary imaging device and a phase difference detecting module, eliminating the need for a separate dedicated phase difference sensor while achieving fast autofocus performance through software-based phase difference calculation from the image sensor data.
Data Source
AI summary
There is provided an imaging apparatus including a first focus detection unit that has a plurality of first focus detection areas in a photographed screen, and detects a first defocusing amount in the first focus detection areas, a second focus detection unit that has a plurality of second focus detection areas in a photographed screen, and detects a second defocusing amount in the second focus detection areas, a defocusing amount selection unit that selects which of the first defocusing amount detected by the first focus detection unit and the second defocusing amount detected by the second focus detection unit is used, and a focus control unit that performs focus control by moving a focus lens on the basis of the defocusing amount selected by the defocusing amount selection unit.