Shape Measurement Apparatus with Dynamic Focus Adjustment
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Solution Overview
Problem
In light-section shape measurement methods, achieving precise focus on measurement objects with fluctuating distances between the object and the image capturing apparatus is challenging, especially when the object is inclined or position-deviated, leading to blurred images and reduced measurement accuracy.
Innovation Solution
A shape measurement apparatus that includes a linear light position detection unit, a distance computation unit, and a focus adjustment unit, which calculates the distance to the measurement object using reference positions and angles, and adjusts the focus accordingly, enabling precise shape measurement without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focus is adjusted based on predetermined object size and reference distance, then clear images can be obtained for standard objects, but measurement accuracy deteriorates when object distance fluctuates or objects are position-deviated
Solution Approach 1:
The patent implements feedback by detecting the actual position of linear light in captured images and using this information to dynamically adjust focus. The system continuously monitors the linear light position and modifies focus settings based on detected deviations, creating a closed-loop control system that adapts to distance fluctuations and position deviations in real-time
Solution Approach 2:
The patent applies preliminary action by establishing a reference linear light position under ideal focusing conditions before actual measurement begins. This reference position serves as a baseline for detecting subsequent focus deviations and guiding corrective focus adjustments, enabling the system to maintain accuracy despite varying object distances
2Measurement precision
If additional distance sensors are installed to detect object distance, then focus accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies self-service by enabling the image capturing apparatus to automatically detect its own focus status through analysis of the captured linear light position. The system uses the captured image data itself to determine whether focusing is accurate, eliminating the need for separate distance sensors or external focus detection devices
Solution Approach 2:
The patent demonstrates multi-functionality by making the image capturing apparatus perform dual functions: both capturing shape measurement data and detecting focus accuracy. The same camera that records the linear light pattern also determines whether proper focus is achieved by analyzing the position and clarity of the captured linear light, removing the need for dedicated focus detection hardware
3Measurement precision
If focus adjustment is performed by moving the focus lens to and fro, then accurate focus can be achieved, but measurement time increases
Solution Approach 1:
The patent uses feedback to determine the direction and magnitude of focus adjustment needed by comparing the detected linear light position with the reference position. This allows the system to make targeted, efficient focus adjustments rather than performing time-consuming trial-and-error lens movements, significantly reducing focus adjustment time while maintaining accuracy
Solution Approach 2:
The patent applies preliminary action by pre-establishing the reference linear light position that corresponds to ideal focus. This reference serves as a target for focus adjustment, enabling the system to directly move toward the correct focus position based on detected deviations rather than searching through multiple positions, thereby reducing adjustment time
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 allows for precise measurement of the measurement object's shape even when the distance between the object and the image capturing apparatus fluctuates, ensuring clear images and maintaining high measurement accuracy without the need for additional sensors or lengthy focus adjustment processes.
Implementation Method 1
it is necessary to achieve focus so that the linear light 12 is shown thin and clear in the shot image A. This requires the focus of the image capturing apparatus 20 to be accurately adjusted to be set on the measurement surface 5a
Data Source
AI summary
[Object] To provide a shape measurement apparatus that, in measuring the unevenness shape of a measurement object by a light-section method, enables the shape of the measurement object to be measured precisely even when the distance between the measurement object and an image capturing apparatus fluctuates.[Solution] Provided is a shape measurement apparatus including: a linear light position detection unit that detects, from a captured image of linear light applied to a measurement object by a linear light irradiation apparatus that is captured by an image capturing apparatus, a linear light position of the linear light; a distance computation unit that computes a distance from the image capturing apparatus to the measurement object, on the basis of a distance difference between a reference linear light position detected by the linear light position detection unit when the measurement object is positioned at a position of a predetermined reference distance from the image capturing apparatus and the linear light position detected by the linear light position detection unit, the reference distance, and an angle formed by an optical axis of the image capturing apparatus and an emission direction of the linear light; a focus adjustment unit that adjusts focus of the image capturing apparatus on the basis of the distance from the image capturing apparatus to the measurement object; and a shape computation unit that computes a shape of the measurement object on the basis of the captured image.