Analyzing Marks on Curved Transparent Walls Using Uniform Virtual Image Illumination
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Solution Overview
Problem
Existing technologies face challenges in accurately reading small patterns or characters on the external surface of curved, reflective, and transparent or translucent materials due to parasitic images caused by internal reflections, and are not suitable for large angular widths or very small features.
Innovation Solution
A method and device using a light source with a uniform and extended illumination surface, where the virtual image of the light source completely covers the mark, and the camera observes this image superimposed with the mark, with optional adaptations such as a backlit diffusing screen, mirrors, and optical elements to minimize parasitic images and align the observation axis with the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional light source is used to illuminate the mark, then the mark can be visible, but parasitic images appear due to internal reflections on the curved transparent surface
Solution Approach 1:
A diffusing screen is introduced as an intermediary element between the light source and the curved transparent surface. This screen diffuses the light before it reaches the mark, preventing direct reflection paths that create parasitic images while still providing sufficient illumination for mark detection.
Solution Approach 2:
The illumination parameters are changed by using an extended light source with specific geometric characteristics rather than a conventional point source. The light source is designed with an extension in the direction perpendicular to the optical axis, which alters the reflection geometry and eliminates parasitic images.
2Illumination intensity
If a point light source is used, then the device is simple, but it cannot provide uniform illumination across the entire mark surface
Solution Approach 1:
The light source is segmented into multiple illumination points distributed along an extended structure. This segmentation allows each point to illuminate a specific portion of the mark, collectively providing uniform illumination across the entire surface without requiring a complex centralized system.
Solution Approach 2:
A diffusing screen serves as an intermediary that redistributes light from the extended source uniformly across the mark surface. This simple passive element achieves uniform illumination without requiring complex active control systems or multiple independent light sources.
3Ease of operation
If the camera observes the mark directly, then the observation is straightforward, but the central zone of the light source creates a dark area that interferes with code reading
Solution Approach 1:
The illumination is designed with local quality variation where the light intensity and distribution are optimized for different regions. The extended light source provides enhanced illumination at the edges and corners of the mark while maintaining sufficient brightness in the central region, ensuring uniform visibility across the entire code area.
Solution Approach 2:
The light source is extended in the dimension perpendicular to the optical axis rather than along the axis. This dimensional change allows the light to illuminate the mark from multiple lateral positions, filling in the dark central zone that would otherwise be blocked by the camera or diffuser center.
4Measurement precision
If a conventional reading device is used, then it can read large codes, but it cannot read very small patterns or characters less than one mm
Solution Approach 1:
The optical parameters of the system are optimized for high resolution by using an extended light source that provides coherent illumination across the entire mark surface. This illumination geometry enhances the contrast and visibility of very small features below one millimeter while maintaining compatibility with larger code formats.
Solution Approach 2:
The light source provides excessive illumination coverage, extending beyond the boundaries of the mark. This ensures that even the smallest features receive sufficient light for detection, while the extended coverage also maintains adaptability for reading larger codes without requiring system reconfiguration.
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
Enables reliable analysis of marks with good uniform contrast, eliminating parasitic images and allowing for accurate reading of small patterns and characters on curved surfaces with improved coverage and resolution.
Implementation Method 1
the camera observes this image superimposed with the mark
Implementation Method 2
a backlit diffusing screen
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
The invention relates to a method for analyzing, by means of a light source (5) having a lighting surface (S) and by means of a camera (6) having an optical observation axis (A), a mark (2) made on the outer surface (3i) of a curved wall (3) made of a translucent or transparent material, characterized in that: - the extended, uniform light source is produced such that: the area of the virtual image (S1) of the lighting surface (S) of the light source (5) completely covers the surface of the mark (2), and such that the luminance of the virtual image (S1) of the lighting surface (S) of the light source (5) is uniform; and – the surface of the mark (2), placed over the surface of the virtual image (S1), is observed so as to enable analysis of the mark (2).