Inspection Lighting Device with Tilted Diaphragm for Defect Contrast
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Solution Overview
Problem
Existing inspection lighting devices struggle to effectively irradiate inspection light onto complex or small products, leading to difficulties in detecting defects due to insufficient light intensity, excessive stray light, and inappropriate tilt states of irradiation solid angles, making it hard to distinguish defects from normal parts in imaged images.
Innovation Solution
A lighting device with a surface light source, a lens, and a first diaphragm, where the positions of the light source and lens are set to ensure the image plane is on the inspection object, and the diaphragm adjusts the central axis of irradiation solid angles to be tilted and displaced, allowing for independent control of irradiation range and solid angles to optimize light distribution based on the inspection object's shape and characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diaphragm is used to limit the irradiation range of inspection light, then the amount of stray light is reduced and inspection accuracy is improved, but the light amount reaching the inspection object is reduced making it difficult to detect small defects
Solution Approach 1:
The patent applies local quality by making the irradiation solid angle tilt angle vary across different spatial locations on the inspection object. Specifically, the tilt angle is set to be larger at peripheral portions and smaller at central portions, optimizing light distribution locally for each region to simultaneously reduce stray light and maintain sufficient light amount for defect detection
Solution Approach 2:
The patent changes the parameter of irradiation solid angle tilt angle across different locations. By adjusting this parameter spatially (larger at periphery, smaller at center), the system optimizes both stray light reduction and light amount distribution, resolving the contradiction between inspection accuracy and light quantity
2Use of energy by moving object
If the irradiation solid angle is increased to improve defect detection, then more light reaches the object, but the tilt states become inappropriate for the inspection object shape reducing detection accuracy
Solution Approach 1:
The patent implements local quality by setting different irradiation solid angle tilt angles for different spatial locations. The tilt angle is configured to be larger at peripheral portions and smaller at central portions, matching the local geometric characteristics of the inspection object to optimize both light intensity and detection accuracy at each location
3Measurement precision
If the inspection light is irradiated at high intensity to detect small defects, then the contrast improves, but the reflected light from other points increases making defects difficult to distinguish
Solution Approach 1:
The patent applies local quality by configuring the irradiation solid angle tilt angle to vary across the inspection object surface. This spatial variation ensures that light is directed precisely at the intended inspection point while minimizing illumination of surrounding areas, thereby reducing reflected light from non-inspection points and improving defect contrast
Solution Approach 2:
The patent converts the potential harm of stray light and reflected light into a benefit by using the spatial variation of tilt angles to direct light precisely where needed. The configuration transforms what would be harmful scattered light into controlled, location-specific illumination that enhances defect visibility
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 ensures that most inspection light reaches the object, adjusts irradiation solid angles for defect detection, and optimizes contrast, enabling the detection of small defects that were previously difficult to identify through machine vision.
Implementation Method 1
a lens that is provided on a light axis of inspection light emitted from the surface light source, and between an inspection object and the surface light source
Implementation Method 2
positions of the surface light source and the lens with respect to the inspection object are set such that an image plane on which the surface light source is imaged is present on the inspection object
Implementation Method 3
a first diaphragm that is provided between the surface light source and the lens, wherein a position of the first diaphragm with respect to the lens is set such that a central axis of an irradiation solid angle determined by a part of the inspection light
Implementation Method 4
a central axis of an irradiation solid angle determined by a part of the inspection light, which is incident on an outer edge part of the image plane, is displaced from the light axis and tilted by a predetermined amount
Data Source
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AI summary
In order to provide a lighting device for inspection and lighting method for inspection that, with use of inspection light, make it possible for a difference between a defect and a normal part, such as contrast, to appear, the lighting device for inspection is provided with: a surface light source 1 that emits the inspection light; a lens 2 that is provided on a light axis LX of the inspection light emitted from the surface light source 1, and between an inspection object W and the surface light source 1; and a first diaphragm 31 that is provided between the surface light source 1 and the lens 2, or between the lens 2 and the inspection object W, wherein: positions of the surface light source 1 and the lens 2 with respect to the inspection object W are set such that an image plane IM on which the surface light source 1 is imaged is present near the inspection object W; and a position of the first diaphragm 31 with respect to the lens 2 is set such that the central axis of an irradiation solid angle determined by a part of the inspection light, which is incident on an outer edge part of the image plane IM, is parallel to the light axis LX, or is displaced from the light axis and tilted by a predetermined amount.