Endoscope Zoom Lens Autofocus via Image Evaluation
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Solution Overview
Problem
Existing endoscope systems face challenges in reducing the size of their optical systems while maintaining focused images, particularly when using a zoom lens without an autofocus mechanism.
Innovation Solution
The endoscope system incorporates a processor device with an image acquisition processor that drives a zoom lens based on a freeze button press, acquiring continuous images before and after the press, calculating evaluation values, selecting the optimal image with the highest value, and displaying it to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an autofocus mechanism is incorporated into the endoscope, then focused images can be obtained automatically, but the optical system increases in size and weight
Solution Approach 1:
The patent extracts the autofocus function from the optical system and relocates it to the image processing unit. Instead of using mechanical autofocus components in the optical path, the system captures multiple images at different focus positions and performs autofocus processing through image evaluation and selection, thereby eliminating the need for heavy autofocus mechanical components while maintaining automatic focusing capability
Solution Approach 2:
The patent replaces the mechanical autofocus system with a computational approach. Rather than using motors and lens driving mechanisms to physically adjust focus, the system uses image acquisition at multiple focus positions combined with image processing algorithms to evaluate and select the sharpest image, substituting mechanical action with computational processing
2Ease of operation
If the depth of field is increased to reduce manual focusing difficulty, then focusing becomes easier, but the observation site cannot be enlarged in close proximity
Solution Approach 1:
The patent performs preliminary action by capturing multiple images at different focus positions before the user needs to select a focused image. The image acquisition unit acquires a plurality of images including out-of-focus images and in-focus images in advance, then the image processing unit evaluates these pre-captured images to determine the optimal focused image, eliminating the need for real-time manual focusing adjustment
3Measurement precision
If manual focusing is performed by moving the endoscope back and forth, then focused images can be obtained, but the user burden increases particularly in shallow depth of field situations
Solution Approach 1:
The patent implements self-service by enabling the system to automatically perform the focusing task that would otherwise require manual user intervention. The image acquisition unit automatically captures multiple images at different focus positions, and the image processing unit automatically evaluates these images using sharpness metrics and selects the optimal focused image, allowing the system to serve itself without requiring the user to manually adjust focus or evaluate multiple images
Data Source
AI summary
A lens driving processor is configured to drive a zoom lens in accordance with pressing of a freeze button, and an image acquisition processor is configured to select a post-press evaluation frame image having a highest evaluation value, as an optimal image, from post-press evaluation frame images as examination images for which the evaluation values have been calculated among the examination images acquired in conjunction with movement of the zoom lens during a time after the pressing in a certain time before and after the pressing of the freeze button, and to display the optimal image.