Prepreg Gap Inspection on Curved Surfaces
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Solution Overview
Problem
Existing prepreg pasting state inspection methods are inaccurate when the pasting target body has shape changed portions, such as curved surfaces, due to adverse effects on imaging and irradiation conditions.
Innovation Solution
A prepreg pasting state inspection apparatus with a slit light irradiation unit, imaging unit, determination unit, distance measurement unit, focus adjusting unit, light amount adjusting unit, and depth of field adjusting unit, which allows for accurate gap detection between prepregs by adjusting focus and light conditions based on distance measurements, even on shape changed surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed focus position is used for imaging, then the device structure is simple, but imaging accuracy deteriorates on curved surfaces
Solution Approach 1:
The patent implements dynamic focus adjustment by moving the imaging unit (camera) along the optical axis based on distance measurements from the distance measurement unit. This allows the focus position to adapt continuously to the curved surface geometry, maintaining imaging accuracy while the system remains structurally integrated and relatively simple.
Solution Approach 2:
The system uses feedback from the distance measurement unit to automatically adjust the focus position of the imaging unit. The measured distance information is fed back to control the camera's focal plane, ensuring that the imaging remains sharp on curved surfaces without requiring complex manual intervention or overly complicated mechanical structures.
2Measurement precision
If light amount is not adjusted on curved surfaces, then the system is simple, but blown-out highlights occur affecting inspection accuracy
Solution Approach 1:
The light amount adjusting unit dynamically modifies illumination intensity based on the measured distance to the surface. As the imaging unit moves closer to or farther from curved portions, the system automatically adjusts the light output to prevent overexposure on protruding surfaces while maintaining adequate illumination on recessed areas, ensuring consistent inspection quality.
Solution Approach 2:
The system employs feedback control where distance measurement results are used to automatically regulate the illumination light amount. This closed-loop control prevents blown-out highlights on curved surfaces by adjusting lighting conditions in real-time based on actual surface geometry, without requiring complex additional hardware.
3Measurement precision
If depth of field is not adjusted, then the device structure is simple, but defocusing occurs on shape changed portions
Solution Approach 1:
The depth of field adjusting unit dynamically modifies the optical depth of field based on distance measurements. When the imaging unit is positioned closer to curved or irregular surface portions, the system adjusts the depth of field parameters to ensure these areas remain within the sharp focus range, maintaining imaging clarity throughout the inspection process.
Solution Approach 2:
The system uses feedback from continuous distance measurements to automatically adjust depth of field settings. This ensures that the focal depth adapts to the varying geometry of the pasting target body, keeping curved and irregular portions properly focused without requiring complex mechanical adjustments or additional optical components.
4Measurement precision
If focus and light conditions are not adjusted for curved surfaces, then the inspection system is simple, but inspection accuracy deteriorates on shape changed portions
Solution Approach 1:
The inspection system implements dynamic adjustment of both focus position and light amount based on real-time distance measurements. This allows the system to adapt to curved and irregular surface geometries, maintaining high inspection accuracy while keeping the overall system structure integrated and relatively simple through automated control mechanisms.
Solution Approach 2:
The system employs comprehensive feedback control where distance measurement information is used to simultaneously adjust focus position and illumination light amount. This coordinated feedback mechanism ensures that both imaging clarity and lighting conditions are optimized for curved surfaces, achieving high inspection accuracy without requiring overly complex separate adjustment systems.
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 inspection of prepreg pasting states on surfaces with curved or irregular shapes by ensuring proper focus and light conditions, preventing defects like blown-out highlights and defocusing.
Implementation Method 1
a distance measurement unit for measuring a distance between a reference position and the irradiation region
Implementation Method 2
the focus adjusting unit may have a driving unit for moving the movable lens based on the signal from the distance measurement unit
Implementation Method 3
The laser (the line laser) 21 emits slit light LA along an inclined plane so that a pattern X of the slit light LA are formed across the adjacent prepregs 4
Implementation Method 4
when an irradiation region formed with the projected lines L1 to L3 is imaged by the camera 22 from above, image data shown in FIG. 3 can be obtained
Data Source
AI summary
Even when a pasting target body to which prepregs are pasted has a shape changed portion such as a curved portion, prepreg pasting states are accurately inspected. A prepreg pasting state inspection apparatus for inspecting a gap between adjacent prepregs on a pasting target body has a laser for emitting slit light along an inclined plane so that a projected pattern of the slit light is formed across the adjacent prepregs, a camera for imaging an irradiation region of the laser, and a control unit for determining whether the gap between the adjacent prepregs is within an allowance based on a signal from the camera. The apparatus also has a range sensor for measuring a distance between a reference position and the irradiation region, and focus adjusting units for adjusting focus positions of the camera and the laser based on the signal from the range sensor.