Card Scanner Lighting Asymmetry to Suppress Glossy Reflections
Solution Overview
Problem
Card scanners face challenges in capturing clear images of glossy documents due to the appearance of bright regions caused by reflective surfaces.
Innovation Solution
The solution involves optimizing the lighting setup by varying the locations and vertical distances of light sources, using a pixel comparator process to remove bright regions, and employing spatial filtering and merging techniques to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light sources are positioned to illuminate the card surface, then the card surface is adequately lit for scanning, but bright regions appear on glossy surfaces due to reflections
Solution Approach 1:
The illumination system is divided into multiple independent light sources positioned at different locations and angles. Each light source illuminates a different region of the card, and their combined effect provides uniform illumination while distributing reflection points across the image, making them less prominent and easier to process.
Solution Approach 2:
Different regions of the card surface receive light at different angles and intensities based on their local properties. The system adapts illumination characteristics to local surface characteristics, providing optimal lighting for each area while minimizing localized reflections that would otherwise dominate the entire image.
2Object-affected harmful factors
If multiple light sources are used to reduce bright regions, then illumination coverage is improved, but device complexity increases
Solution Approach 1:
Multiple light sources are merged into a single integrated lighting assembly that functions as one cohesive unit. The control system treats the multiple light sources as a unified system, switching between pre-configured illumination patterns rather than independently controlling each light source, thereby reducing control complexity while maintaining the benefits of multiple light sources.
Solution Approach 2:
The system changes illumination parameters (intensity, angle, duration) dynamically based on the scanning requirements and surface characteristics detected. By adjusting these parameters, the system optimizes illumination effectiveness while minimizing reflection issues without requiring complex mechanical adjustments or additional components.
3Illumination intensity
If light sources are positioned closer to the card for better illumination, then illumination intensity increases, but reflection problems worsen
Solution Approach 1:
The light sources are positioned asymmetrically at various angles relative to the card surface rather than symmetrically around it. This asymmetric arrangement ensures that reflections from different light sources land at different locations on the card image, preventing concentrated reflection hotspots while maintaining adequate illumination intensity.
Solution Approach 2:
The illumination approach transitions from a single-dimension vertical lighting arrangement to a multi-dimensional configuration where light sources are distributed across different spatial dimensions and angles. This three-dimensional lighting arrangement provides intense illumination while dispersing reflection points across the image plane, reducing their visual impact.
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 approach effectively reduces the occurrence of bright regions in captured images, resulting in clearer and more accurate scans of glossy documents.
Implementation Method 1
A first light source and a second light source are located in a camera housing at different locations so that bright regions resulting from reflection of light from the first light source and bright regions resulting from reflection of light from the second light source occur at different locations of a card image
Implementation Method 2
bright regions resulting from reflection of light from the first light source and bright regions resulting from reflection of light from the second light source
Data Source
AI summary
A card scanner includes a card support mechanism for receiving a card and a first camera. A first light source is mounted so that a first image of a first side of the card captured by the first camera reflects to the first camera so that a first bright region created by light reflected by the first side of the card from the first light source is within a first location on the first side of the card. A second light source is mounted so that a second image of the first side of the card captured by the first camera reflects to the first camera so that a second bright region created by light reflected by the first side of the card from the second light source is within a second location on the first side of the card, wherein the first location and the second location do not overlap. An image processor combines the first image of the first side of the card with the second image of the first side of the card to produce a first combined image, the first bright region and the second bright region being filtered from the first combined image by the image processor.