Transparent Substrate Inspection Using Perpendicular Illumination and Template Matching
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Solution Overview
Problem
Existing methods for inspecting transparent substrates fail to accurately determine if parts are correctly placed at predetermined positions, often confusing part presence with defects.
Innovation Solution
An inspection system comprising an illuminating device, an imaging device, and a processing device that emits light perpendicular to the transparent substrate, captures images, and uses templates to differentiate between real and virtual images of parts, improving accuracy by suppressing irrelevant reflections and determining positional relationships between real and virtual images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection methods are used for transparent substrates, then surface defects can be detected, but part placement accuracy cannot be determined and parts are confused with defects
Solution Approach 1:
The patent segments the inspection process into two distinct phases: defect inspection (detecting surface defects on the transparent substrate) and part placement inspection (determining whether parts are correctly positioned). This segmentation allows each phase to use optimized inspection methods and criteria, preventing confusion between parts and defects while improving overall measurement precision.
Solution Approach 2:
The patent introduces reference marks as intermediary elements on the transparent substrate. These reference marks serve as mediators that provide positional reference information, enabling the inspection system to accurately determine part placement positions and distinguish parts from defects by comparing their locations against the known reference mark positions.
2Measurement precision
If oblique angle illumination is used to detect surface defects, then defects can be identified, but part placement positions cannot be determined
Solution Approach 1:
The patent employs periodic action by sequentially performing two distinct inspection operations: first, defect inspection using oblique angle illumination to detect surface defects; second, part placement inspection using perpendicular illumination and template matching to determine part positions. This periodic alternation between different inspection modes allows both defect detection and positional information acquisition without interference.
Solution Approach 2:
The patent changes illumination parameters (angle, intensity distribution) and image processing parameters (template matching algorithms, position calculation methods) according to the specific inspection objective. For defect detection, oblique angle illumination is used; for part placement determination, perpendicular illumination with template matching is applied, optimizing each process for its specific purpose.
3Ease of operation
If simple presence detection is used, then it can be determined if something is present on the substrate, but it cannot identify whether it is a defect or a part
Solution Approach 1:
The patent performs preliminary action by pre-storing template images that represent the expected appearance and position of parts on the substrate. During inspection, these pre-stored templates are used as reference standards for comparison, enabling the system to automatically identify objects as either parts or defects based on their match with the template, thus achieving accurate identification while maintaining operational simplicity.
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
Enhances inspection accuracy by clearly distinguishing part positions from defects, allowing for precise determination of part placement and reducing errors in manufacturing processes.
Implementation Method 1
an illuminating device (10) for emitting light (L1) to a front surface (210) of a transparent substrate (200)
Implementation Method 2
an imaging device (20) for receiving the light (L1) transmitted through the transparent substrate (200)
Data Source
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AI summary
An object of one aspect according to the present disclosure would be to improve accuracy of inspection for a product including a transparent substrate. The inspecting method is for a product including a transparent substrate and a part placed at a predetermined position within a front surface of the transparent substrate, and includes an imaging step and an evaluating step. The imaging step is a step of taking an image (P10) of the front surface by an imaging device with the front surface being illuminated by an illuminating device. The evaluating step is a step of evaluating a degree of matching between an image which is derived from the image (P10) taken by the imaging device and shows a position corresponding to the predetermined position and its vicinity (R1 to R12), and a template (T1, T2, T3). The template (T1, T2, T3) is indicative of a positional relationship between a real image (300R) and a virtual image (3001), of the part in a case where the part is placed at the predetermined position correctly.