Shadow Shape Measurement Calibration With a Movable Dimming Filter
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Solution Overview
Problem
Conventional shape measuring devices face errors due to diffraction fringes when measuring long objects, leading to inaccurate results and the inability to adjust light amounts within the dynamic range of the image sensor, preventing effective calibration.
Innovation Solution
Incorporating a dimming filter unit between the illumination and imaging units to adjust the illumination light amount, allowing calibration within the dynamic range of the image sensor, and using a movement driving unit to switch between calibration and measurement positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If saturation of light receiving amount is used to make the background white and eliminate diffraction fringes, then measurement precision is improved, but calibration cannot be performed because the light amount cannot be adjusted within the dynamic range
Solution Approach 1:
The patent applies the dynamics principle by making the dimming filter movable between two positions: a first position where the filter is disposed between the illumination unit and image sensor to reduce light amount during calibration, and a second position where the filter is disposed away to allow full light intensity during measurement. This dynamic repositioning enables the system to adapt between calibration and measurement modes, resolving the contradiction between calibration capability and measurement precision.
2Length of moving object
If parallel light is emitted to measure long measurement targets, then the ability to measure long objects is improved, but diffraction fringes are generated causing measurement errors
Solution Approach 1:
The patent applies the intermediary principle by introducing a dimming filter as a mediating element between the illumination unit and the image sensor. This filter serves as an intermediary that controls and adjusts the light amount, enabling the system to manage diffraction effects while maintaining the parallel light configuration necessary for measuring long objects. The filter acts as a buffer that allows precise control over light intensity without altering the fundamental measurement geometry.
3Measurement precision
If the light amount is increased to exceed the dynamic range for calibration, then calibration accuracy is improved, but the image sensor cannot properly receive and measure the light amount
Solution Approach 1:
The patent applies the parameter changes principle by dynamically adjusting the light amount parameter through the dimming filter. During calibration, the filter reduces the light amount from the high-intensity parallel light to a level within the image sensor's dynamic range, enabling accurate measurement. The system changes the light transmission parameter of the filter based on the operational mode (calibration or measurement), allowing the same hardware configuration to support both high-accuracy calibration and normal measurement operations.
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
Enables accurate calibration of illumination light within the image sensor's dynamic range, reducing errors and ensuring precise contour shape measurements by adjusting light amounts automatically.
Implementation Method 1
a dimming filter unit 2 that reduces the amount of incident light and emits the light
Implementation Method 2
a shadow image of the measurement target disposed between an illumination unit and an imaging unit in a case of measurement, the shadow image being generated by the imaging unit imaging a shadow of the measurement target, the shadow being formed by illumination light emitted from the illumination unit
Data Source
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AI summary
A shape measuring device of the present invention includes an image processing unit that obtains a contour shape of a measurement target having a plate shape based on a shadow image of the measurement target disposed between an illumination unit and an imaging unit in a case of measurement, the shadow image being generated by the imaging unit imaging a shadow of the measurement target, the shadow being formed by illumination light emitted from the illumination unit. A dimming filter unit is disposed between the illumination unit and the imaging unit in a case of calibration, and an amount of illumination light emitted from the illumination unit is calibrated based on a light receiving amount of the illumination light emitted from the illumination unit and received by the imaging unit via a dimming filter unit 2.