Focus Lens Control Switching for Camera Reliability
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Solution Overview
Problem
Imaging devices with inner focus type lenses experience reduced reliability of the focus adjusting mechanism due to excessive load from continuous autofocus control during long-term use and remote-controlled zoom-in and zoom-out operations.
Innovation Solution
An imaging device that switches between autofocus control using an evaluation value and focus control by a cam curve based on the comparison of focal depth and imaging range, with the control means moving the focus lens in concert with the zoom lens, thereby reducing the load on the focus adjusting mechanism and preventing blurring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If autofocus control by hill-climbing method is performed continuously during long-term use and remote-controlled zoom-in and zoom-out operations, then the imaging device can maintain focus on desired subjects, but the focus adjusting mechanism is operated continuously causing excessive load and rapid reduction in reliability
Solution Approach 1:
The patent applies periodic action by switching between two focus control methods based on operational conditions: autofocus control by hill-climbing method is used when focal depth is less than imaging range, while focus control by cam curve is used when focal depth is greater than or equal to imaging range. This periodic switching reduces continuous operation of the focus adjusting mechanism, thereby improving reliability during long-term use and remote-controlled operations.
Solution Approach 2:
The patent changes the control parameter from continuous autofocus operation to conditional switching based on the relationship between focal depth and imaging range. By monitoring these parameters and adjusting the control method accordingly, the system reduces excessive load on the focus adjusting mechanism while maintaining imaging quality.
2Manufacturing precision
If autofocus control using evaluation value is performed, then the focus lens can be moved to achieve sharp focus, but the control complexity increases compared to simple cam curve control
Solution Approach 1:
The patent segments the focus control process into two distinct modes: autofocus control by hill-climbing method for situations requiring precise focus adjustment (when focal depth < imaging range), and focus control by cam curve for situations where the imaging range is sufficient (when focal depth >= imaging range). This segmentation allows the system to use complex control only when necessary, reducing overall control complexity while maintaining precision when needed.
Solution Approach 2:
The patent implements dynamic control by automatically switching between different focus control methods based on real-time conditions (focal depth and imaging range relationship). This dynamic adaptation allows the system to optimize between precision and simplicity depending on the operational context, rather than using a fixed complex control mechanism.
Data Source
AI summary
Disclosed herein is an imaging device having a lens including a zoom lens and a focus lens; an image sensor for outputting an imaging result of an optical image formed by the lens; a signal processor for processing the imaging result to output a video signal; a detector for processing the video signal to output an evaluation value indicative of the degree of focusing; a memory for storing data of an imaging range where a focused image is ensured, by using a cam curve of the lens; and a controller for moving the focus lens in concert with the zoom lens; wherein when a focal depth detected according to a current position of the zoom lens is less than the imaging range at the current position of the zoom lens, the controller performs autofocus control using the evaluation value to move the focus lens; and when the focal depth is greater than the imaging range at the current position of the zoom lens, the controller performs focus control by the cam curve to move the focus lens. Thus, the autofocus control and the focus control by the cam curve are switched to each other according to the result of comparison between the focal depth and the imaging range at the current position of the zoom lens.