Endoscope Movable Lens Autofocus and Magnification Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Endoscope systems with a zoom function face challenges in maintaining focus due to the shallow depth of field and pulsation of objects, making it difficult for users to keep the object in focus during zoom observation, especially when the distance from the objective lens to the object changes.
Innovation Solution
An imaging device with a movable lens that adjusts the in-focus object plane position along with the angle of view, incorporating a focus control section for autofocus, a reference lens position setting section, and a magnification correction section to stabilize the image by setting a reference lens position based on the movable lens's wobbling operation and performing a magnification correction process to reduce changes in the angle of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the movable lens is moved to increase magnification during zoom observation, then the in-focus object plane position decreases and magnification increases, but the depth of field becomes shallow (1 mm or less) making it difficult to bring the object into focus
Solution Approach 1:
The system performs autofocus operations automatically without requiring manual user intervention. The focus control section executes AF operations by autonomously controlling the movable lens position based on contrast evaluation, enabling the system to self-adjust focus despite the shallow depth of field at high magnification
Solution Approach 2:
The system calculates contrast values from the image to evaluate the in-focus state and uses this feedback to control the movable lens position. The focus control section continuously monitors focus quality and adjusts the lens position accordingly, creating a closed-loop feedback system that maintains sharp focus during zoom observation
2Reliability
If full-time autofocus operation is performed to maintain focus during object distance changes, then the object can remain in focus despite pulsation, but the angle of view changes due to movable lens position changes during wobbling operation
Solution Approach 1:
The reference lens position is set in advance based on the movable lens moving range during the wobbling operation. This reference position serves as a baseline for subsequent magnification correction, allowing the system to pre-calculate the necessary compensation for angle of view changes before they occur
Solution Approach 2:
The magnification correction section dynamically adjusts the angle of view parameter by correcting image magnification based on the difference between the actual movable lens position and the reference lens position. This parameter change compensates for the angle of view variation caused by autofocus operations, maintaining stable image composition
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
The solution enables accurate autofocus and stable image magnification, reducing the stress on users during diagnosis by maintaining focus even when the object distance changes, and effectively managing the shallow depth of field issue.
Implementation Method 1
an image sensor that photoelectrically converts an object image formed by the objective lens to acquire an image
Data Source
AI summary
An imaging device includes an objective lens that includes a movable lens that is configured so that an in-focus object plane position is changed along with a change in angle of view, an image sensor that acquire an image, a focus control section that implements an autofocus (AF) operation by controlling a position of the movable lens, a reference lens position setting section that sets a reference lens position based on a moving range of the movable lens during a wobbling operation, the wobbling operation being performed every given cycle during the AF operation, and a magnification correction section that performs a magnification correction process that reduces a change in the angle of view of the image due to a change in the position of the movable lens during the wobbling operation relative to the reference lens position.