Sheet Inspection Device Using Linear Light Source for Compact High-Sensitivity Defect Detection
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Solution Overview
Problem
Conventional inspection methods for sheet objects require large installation spaces or suffer from reduced detection sensitivity due to differences in unit configurations, leading to inefficient inspection of irregularities across the entire width of the sheet object.
Innovation Solution
The inspection device employs a linear irradiation unit with its longitudinal direction parallel to the sheet conveyance direction, and a projection unit and image capture unit positioned outside the sheet width, ensuring consistent detection sensitivity and reduced space requirements by using a linear light source that maintains light intensity over increased distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single irradiation unit and a single image capture unit are used to inspect all width directions of the sheet object, then the installation space is reduced, but the detection sensitivity becomes insufficient due to the need to increase the distance between the units and the sheet object
Solution Approach 1:
The patent divides the inspection system into multiple irradiation units and multiple image capture units arranged in the width direction of the sheet object. Each unit is responsible for inspecting a specific region, allowing the system to maintain high detection sensitivity across the entire width without requiring excessive installation space. This segmentation enables parallel inspection of different regions simultaneously.
Solution Approach 2:
The patent arranges the irradiation units and image capture units in the width direction (lateral dimension) rather than only in the conveyance direction. This dimensional arrangement allows multiple units to operate at optimized distances from the sheet object, maintaining detection sensitivity while efficiently utilizing installation space through spatial distribution.
2Area of stationary object
If multiple irradiation units and image capture units are arranged in the width direction to reduce installation space, then the space requirement is reduced, but a difference in detection sensitivities is generated due to differences between respective units and installation accuracy
Solution Approach 1:
The patent employs irradiation units that emit light at controlled angles (including substantially perpendicular incidence) and uses optical systems with standardized parameters to ensure consistent illumination and detection conditions across all units. This standardization of optical parameters compensates for variations in installation accuracy and ensures uniform detection sensitivity throughout the inspection area.
Solution Approach 2:
The patent designs the multiple irradiation units and image capture units with identical or standardized configurations, making each unit functionally equivalent. This universality ensures that all units perform the same inspection function with the same sensitivity characteristics, eliminating detection sensitivity differences caused by unit variations.
3Measurement precision
If the longitudinal direction of the irradiation unit and the scanning direction of the image capture unit are inclined at a certain angle with respect to the width direction of the sheet object, then the detection sensitivity of irregularly shaped defects is improved, but the installation space increases
Solution Approach 1:
The patent segments the inspection system into multiple units arranged in the width direction, with each unit configured to inspect its specific region. By distributing units laterally rather than requiring a single large inclined system, the patent achieves comprehensive coverage and high detection sensitivity while minimizing the overall installation footprint through compact spatial arrangement.
Solution Approach 2:
The patent transitions from a single inclined configuration in the conveyance direction to a multi-unit arrangement in the width direction. This dimensional shift allows the system to achieve the benefits of inclined illumination for defect detection while consolidating the installation space through lateral distribution of compact units.
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 configuration allows for accurate and stable detection of irregularities across the sheet object's width without compromising sensitivity, even at greater distances, enabling efficient inspection of defects like scratches and stripes.
Implementation Method 1
an irradiation unit (3) emits light toward a sheet object (1), and the light that has transmitted through the sheet object (1) or that has reflected from the sheet object (1) is projected on a projection unit (4)
Implementation Method 2
an image capture unit (5) captures an image of the projection image projected on the projection unit (4)
Data Source
Figure 1~2
Figure 3A~3D
Figure 4A~4D
AI summary
An inspection device for a sheet object according to the present invention includes an irradiation unit configured to irradiate , with irradiation light, the sheet object that is continuously conveyed; a projection unit configured to project transmitted light or reflected light from the sheet object; an image capture unit configured to capture a projection image projected on the projection unit; and a data processing unit that detects a defect present on the sheet object from image data captured by the image capture unit. The longitudinal direction of the irradiation unit viewed from a direction perpendicular to a traveling surface of the sheet object is the same as a conveyance direction of the sheet object, and the irradiation unit emits light spreading in a sheet width direction of the sheet object.