Dual Optical System Camera for Rapid Phase-Difference Autofocus
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Solution Overview
Problem
Existing image capturing apparatuses with wide zoom ranges face challenges in achieving fast and accurate autofocus due to the complexity of configuration and time consumption in focusing, particularly with contrast AF and phase-difference AF methods.
Innovation Solution
The use of a digital camera equipped with a first and second image capturing optical system, spaced apart with different angles of view, which performs a correlation operation after scaling factor conversion to quickly detect subject distance and enable rapid autofocus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single image capturing optical system is used, then the device complexity is reduced, but the zoom range is limited
Solution Approach 1:
The patent divides the image capturing function into multiple optical systems with different focal lengths (first image capturing optical system with focal length f1, second image capturing optical system with focal length f2). Each optical system captures images at different zoom levels, enabling a wider overall zoom range without requiring a single complex variable focal length lens
2Loss of time
If contrast AF is used, then the configuration is simplified, but the focusing time increases
Solution Approach 1:
The patent performs correlation operation between images from the first and second optical systems to preliminarily detect the subject distance before focusing. This preliminary distance detection provides an initial focus position estimate, significantly reducing the time required for contrast AF to converge to the optimal focus point
3Loss of time
If phase-difference AF module is added, then the focusing speed is improved, but the device complexity increases
Solution Approach 1:
The patent makes the first and second image capturing optical systems serve dual purposes: they simultaneously function as imaging lenses for capturing pictures and as distance detection means for phase-difference AF. By spacing the two optical systems apart and using their parallax, the system achieves fast phase-difference focusing without requiring a separate dedicated distance detection module
4Adaptability or versatility
If multiple image capturing optical systems with different focal lengths are used, then the zoom range is widened, but the autofocus accuracy decreases
Solution Approach 1:
The patent performs scaling factor conversion on the images from the first and second optical systems to normalize their different focal length parameters. This parameter adjustment enables accurate correlation operation between images of different scales, ensuring precise distance detection and autofocus accuracy across the entire zoom range
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 configuration allows for a wide zoom range while ensuring quick and accurate autofocus operations, eliminating the need for a separate distance detection module and simplifying camera design.
Implementation Method 1
a first image capturing optical system; a second image capturing optical system which is spaced apart from the first image capturing optical system by a predetermined distance and differs from the first image capturing optical system in terms of an angle of field
Implementation Method 2
computing means which computes a distance to a subject by means of performing correlation operation of a first image captured by the first image capturing optical system and a second image captured by the second image capturing optical system
Data Source
AI summary
The present invention provides a digital camera which has a plurality of image capturing optical systems and quickly performs automatic focusing. A digital camera includes a first image capturing optical system formed from a lens 2 and a first image sensor, and a second image capturing optical system formed from a lens 3 and a second image sensor. An image processor detects a phase difference between an image of a single subject formed on the first image sensor and an image of the same formed on the second image sensor, in order to perform phase-difference AF. Since the lenses 2, 3 have different focal lengths, the image processor executes correlation operation after having performed conversion processing for causing a scaling factor of the image formed by the first image sensor to coincide with that of the image formed by the second image sensor, to thus detect a phase difference.