Imaging Device Dual Illumination for Surface Inspection
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Solution Overview
Problem
Existing imaging devices struggle to accurately measure the reflecting properties of sample surfaces, particularly when the surfaces are illuminated with diffusely reflected light, making it difficult to determine the printed state of the target surface effectively.
Innovation Solution
The proposed imaging device uses a diffuser with a diffuse reflective material, a first light source for diffusely reflected light, and a second light source for direct light, combined with a line sensor to receive irregularly and regularly reflected light, allowing for accurate image data acquisition and colorimetric value determination of the target surface, even on curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the target surface is illuminated with diffusely reflected light only, then the measurement device can simplify the illumination system, but the measurement precision of reflecting properties deteriorates
Solution Approach 1:
The illumination system is segmented into two independent light sources: a first light source for providing diffusely reflected light and a second light source for providing direct light. This segmentation allows each light source to perform a specific function, resolving the contradiction by enabling simple illumination structure while maintaining measurement precision through complementary illumination modes
Solution Approach 2:
The imaging device is designed to perform multiple functions using a unified structure: it can measure both irregularly reflected light (from first light source) and regularly reflected light (from second light source) with the same sensor system. This multi-functionality allows the device to handle various surface types and measurement requirements without increasing overall system complexity
2Device complexity
If only diffusely reflected light is used for illumination, then the device structure is simplified, but the ability to accurately assess printed state on metallic surfaces deteriorates
Solution Approach 1:
The device structure is segmented into two illumination paths with distinct functions: one path (first light source) for diffuse illumination suitable for general surfaces, and another path (second light source) for direct illumination optimized for metallic surfaces with high regular reflectance. This segmentation maintains relatively simple device structure while significantly improving printed state assessment accuracy on metallic surfaces
Solution Approach 2:
Different illumination qualities are applied locally to different measurement needs: diffusely reflected light is used for general surface inspection, while directly reflected light is specifically applied for metallic surface inspection. This local quality differentiation enables accurate printed state assessment on metallic surfaces without complicating the overall device structure
3Measurement precision
If multiple light sources with different illumination angles are used, then the measurement precision of reflecting properties is improved, but the device complexity increases
Solution Approach 1:
The illumination system is divided into two independent light sources with distinct illumination characteristics rather than using a single complex multi-angle illumination system. This segmentation achieves measurement precision improvement by providing both diffuse and direct light components, while keeping device complexity relatively low through simple independent light source placement
Solution Approach 2:
The illumination parameters are changed by using two light sources with fundamentally different illumination modes (diffuse vs. direct) rather than adjusting a single light source to multiple angles. This parameter change approach achieves precise reflecting property measurement while maintaining simple device structure through straightforward optical path design
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 enables the imaging device to easily and accurately assess the printed state of the target surface by distinguishing between irregularly and regularly reflected light, improving measurement accuracy and responsiveness to film thickness variations, especially on metallic surfaces with high regular reflectance.
Implementation Method 1
a diffuser including an inner periphery surface covered with a diffuse reflection material, and configured to diffusely reflect light emitted from the first light source and emit diffusely reflected light to the target surface
Implementation Method 2
a line sensor configured to receive light resulting from reflecting the diffusely reflected light from the target surface
Data Source
AI summary
An imaging device configured to image a printed state of a target surface of a target object for inspection includes: a first light source; a diffuser including an inner periphery surface covered with a diffuse reflection material, and configured to diffusely reflect light emitted from the first light source and emit diffusely reflected light to the target surface; and a line sensor configured to receive light resulting from reflecting the diffusely reflected light from the target surface.