Cover Glass Defect Detection via Asymmetric Lighting and Shutter Control
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Solution Overview
Problem
There is a need to improve the inspection process for electronic devices, particularly for detecting defects and damage in cover glass such as cracks, fractures, scratches, and chips, both during quality assurance testing and after usage, to effectively document flaws or defects in returned devices.
Innovation Solution
An inspection system comprising an enclosure with a lighting assembly and a shutter assembly that captures scattered light from defects using an imaging device, allowing for enhanced visibility of defects on the cover glass, which can be attached to an opaque object like an electronic device, and includes a support fixture for secure positioning and reduced reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional inspection methods are used for cover glass defects, then the inspection process is simple, but the detection precision and visibility of defects is insufficient
Solution Approach 1:
The patent introduces an intermediary optical system comprising a light source, beam splitter, and imaging device positioned at different angles relative to the cover glass. This intermediary setup enables scattered light from defects to be captured and magnified, significantly improving defect detection precision without requiring direct contact or complex modification of the cover glass itself.
Solution Approach 2:
The inspection system employs localized illumination and imaging at specific angles (e.g., 45-degree angle illumination) to highlight defect characteristics in particular regions of the cover glass. This local quality approach allows scattered light from defects to be captured more effectively, enhancing visibility of scratches, chips, and other flaws without inspecting the entire surface uniformly.
2Illumination intensity
If standard lighting conditions are used for inspection, then the setup is simple, but the visibility of scattered light from defects is reduced due to optical noise
Solution Approach 1:
The patent employs asymmetric lighting geometry where the light source illuminates the cover glass at a specific angle (e.g., 45 degrees) while the imaging device captures scattered light at a different angle. This asymmetric arrangement creates a favorable optical path that enhances scattered light from defects while minimizing reflected light and other optical noise, significantly improving defect visibility.
Solution Approach 2:
The system converts the harmful effect of scattered light (which normally creates optical noise and reduces image quality) into a beneficial signal for defect detection. By positioning the imaging device to specifically capture scattered light angles, the system transforms what was previously considered noise into the primary detection mechanism for identifying scratches, chips, and other cover glass defects.
3Measurement precision
If multiple inspection angles are used to improve defect detection, then the detection capability is enhanced, but the inspection time and process complexity increase
Solution Approach 1:
The inspection system uses periodic or pulsed illumination in conjunction with synchronized imaging to capture defect information at optimal angles. This periodic action allows the system to gather comprehensive defect data across multiple angles sequentially rather than simultaneously, improving detection capability while managing inspection time through efficient timing and coordination of the optical components.
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
The system effectively captures images of cover glass defects, reducing optical noise and enhancing image quality, allowing for accurate documentation and identification of flaws, while being cost-effective and adaptable to various device sizes and shapes.
Implementation Method 1
An object, such as an electronic device, may be inspected. For example, a cover glass of the electronic device may be inspected for defects and damage such as cracks, fractures, fragmentations, scratches, chips, and the like.
Implementation Method 2
A shutter assembly may allow, permit or facilitate the capture of scattered light and may restrict or reduce the capture of reflected light
Data Source
AI summary
A cover glass of an electronic device may be inspected for defects and damage such as cracks, fractures, scratches, and chips. The electronic device may be placed in an enclosure with a lighting assembly that emits light to the electronic device, and scattered light from defects and damage of the cover glass is captured by an imaging device. A shutter assembly facilitates the capture of scattered light and reduces the capture of reflected light, which enhances the exposure of defects and damage of the captured image of the cover glass. A mirror facilitates the capture of a side surface of the electronic device.