Autofocus Lens Movable Range Control for Imaging Apparatus
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Solution Overview
Problem
Existing autofocus systems in imaging apparatuses face challenges in accurately setting the focus detection region, leading to erroneous distance measurements due to the size of the autofocus frame being either too large or too small for objects of varying sizes, which can include both the object and background, causing perspective conflicts.
Innovation Solution
The system includes a focus detection unit, a designation unit, and a control unit that adjust the movable range of the focus lens based on whether an object is designated on the screen, setting it to a wider range if an object is identified and a narrower range otherwise, allowing for precise focus adjustment by dividing the focusable range into specific regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant-sized autofocus frame is used for any object, then the device complexity is reduced, but measurement precision deteriorates due to erroneous distance measurements
Solution Approach 1:
The autofocus frame size is made dynamic rather than fixed. The control unit adjusts the autofocus frame size based on detection results - using a first size when no object is detected and a second size when an object is detected. This dynamic adaptation resolves the contradiction by allowing the system to maintain simplicity while achieving accurate measurements through conditional size adjustment.
Solution Approach 2:
The system changes the parameter of autofocus frame size based on detection conditions. When an object is detected within the initial autofocus frame, the system switches to a different frame size appropriate for the detected object. This parameter change enables precise distance measurement while keeping the overall system relatively simple through conditional logic.
2Measurement precision
If the autofocus frame is made large to capture small objects, then measurement precision improves, but harmful factors increase due to background inclusion
Solution Approach 1:
The autofocus process is segmented into multiple stages with different frame sizes. Initially, a first autofocus frame size is used for object detection. Once an object is detected, the system switches to a second autofocus frame size appropriate for the detected object's size. This segmentation allows the system to avoid background interference while maintaining measurement precision by using the appropriate frame size at each stage.
Solution Approach 2:
The system performs preliminary object detection using the first autofocus frame size before switching to the second frame size for actual focusing. This preliminary action identifies the presence and approximate position of the object, allowing the system to then use a more appropriate frame size that excludes background interference while maintaining measurement accuracy.
3Object-affected harmful factors
If the autofocus frame is made small to avoid background, then harmful factors are reduced, but measurement precision deteriorates due to insufficient contrast
Solution Approach 1:
The autofocus frame size dynamically adapts based on detection conditions. The system uses a first frame size for initial detection and switches to a second frame size when an object is detected. This dynamic adjustment ensures the frame is large enough to capture sufficient contrast information from the object while being small enough to exclude background interference, resolving the contradiction between these two requirements.
4Device complexity
If the focus lens movable range is limited to a first range, then device complexity is reduced, but adaptability deteriorates for specific operation modes
Solution Approach 1:
The focus lens movable range is made dynamic based on operation mode. The control unit sets the movable range to a first range in normal still image photographing mode and to a second range in specific operation modes. This dynamic adjustment allows the system to maintain simplicity in common operations while adapting to specialized modes when needed, resolving the contradiction between complexity and versatility.
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 ensures accurate focus detection by setting an appropriate autofocus frame size based on object designation, reducing erroneous measurements and enabling focus adjustment over a wide range without perspective conflicts, thus improving autofocus performance for objects of different sizes.
Implementation Method 1
an imaging unit configured to perform photoelectric conversion on object light incident thereon via a focus lens to acquire an image signal
Data Source
AI summary
An apparatus includes an imaging unit, a focus detection unit configured to detect a focusing state of a focus lens, a designation unit configured to receive a designation of an in-screen position of an object displayed on a display screen, and a control unit configured to control a movable range of the focus lens when the focusing state is detected by the focus detection unit such that if the designation unit does not designate the in-screen position of the object, the movable range is set to be a first range and, if the designation unit designates the in-screen position of the object, the movable range is set to a second range that is wider than the first range.