Endoscope Focus Control Switching Modes for Zoom Depth of Field
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Solution Overview
Problem
Endoscope systems with zoom functions face challenges in maintaining focus due to shallow depth of field, especially when transitioning from wide-angle to telescopic views, making it difficult for users to bring objects into focus, particularly in high-magnification observations.
Innovation Solution
A focus control device and method that dynamically switch between fixed focus and autofocus modes based on the position of the zoom lens relative to a reference point between the wide-angle and telescopic ends, adjusting the focus mode to ensure a monotonic decrease in in-focus object distance as the zoom lens moves from the wide-angle to the telescopic side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the zoom lens is positioned on the telescopic side to increase optical magnification, then the ability to observe part of the digestive tract in detail is improved, but the depth of field becomes shallow making it difficult to bring the object into focus
Solution Approach 1:
The patent applies dynamics by making the focus mode adjustable rather than fixed. The system allows switching between manual focus adjustment and autofocus operation, enabling the focus control to adapt dynamically to different zoom positions and operational needs. This resolves the contradiction by providing flexible focus management that works effectively both at wide-angle and telescopic positions.
Solution Approach 2:
The patent changes the parameter of focus control mode based on the zoom lens position. When the zoom lens is at specific positions (particularly on the telescopic side where depth of field is shallow), the system can switch to autofocus operation to automatically adjust focus, thereby maintaining ease of operation while preserving high optical magnification capability.
2Measurement precision
If the best object distance is decreased on the TELE side to enable closer observation, then the optical magnification during zoom observation is improved, but the depth of field becomes shallow requiring complex focus control
Solution Approach 1:
The patent applies universality by designing a focus control section that performs multiple functions: it can operate in manual mode for general situations and automatically switch to autofocus mode when the zoom lens is positioned where shallow depth of field occurs. This multi-functional approach simplifies the overall device by providing an integrated solution that handles both simple and complex focus requirements through a single unified system.
Solution Approach 2:
The patent implements self-service through the autofocus function, which automatically adjusts the focus without requiring manual intervention from the operator. When the zoom lens is on the telescopic side with shallow depth of field, the autofocus system independently detects and corrects focus issues, thereby reducing device complexity by eliminating the need for additional manual focus control mechanisms.
3Device complexity
If manual focus control is used in fixed focus mode, then the device complexity is reduced, but the ability to maintain focus during zoom transitions is insufficient
Solution Approach 1:
The patent applies feedback by implementing an autofocus function that continuously monitors focus quality and automatically adjusts the focus lens position accordingly. When the zoom lens transitions to positions with shallow depth of field, the feedback mechanism detects the focus degradation and triggers automatic correction, thereby maintaining reliable focus without significantly increasing device complexity.
Solution Approach 2:
The patent applies preliminary action by proactively switching to autofocus mode before focus degradation becomes problematic. When the zoom lens approaches positions where shallow depth of field is expected (based on pre-established reference points), the system preemptively activates autofocus to maintain focus, rather than waiting for focus to be lost and then correcting it.
Data Source
AI summary
A focus control device in an endoscope system, implements an autofocus operation in an appropriate state by setting a focus mode of an imaging optical system. The focus control device includes a focus control section that controls a focus of an imaging optical system that includes at least a zoom lens that adjusts an optical magnification, and sets a focus mode of the imaging optical system, and an image acquisition section that acquires an image through the imaging optical system, the focus mode including a fixed focus mode and an autofocus (AF) mode, and the focus control section switching the focus mode between the fixed focus mode and the AF mode corresponding to whether the zoom lens is positioned on a wide-angle side or a telescopic side relative to a reference point that is situated between a wide-angle end and a telescopic end.