Machine Vision Verification for Embossed Characters
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Solution Overview
Problem
Conventional methods for verifying characters on personalized documents, such as credit cards, struggle with accurately recognizing embossed characters, especially those smaller than 10 characters per inch, and are unreliable in the presence of metallic backgrounds or characters with similar colors, leading to inconsistent results.
Innovation Solution
A vision verification system that illuminates characters on a personalized document from specific angles to create contrast between the perimeter and inner portions, using multiple light sources to capture images perpendicular to the document surface, allowing for reliable recognition and analysis of character size and spacing according to standards like ISO 7811-1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods with Cloudy Day Illuminator are used, then characters can be imaged, but characters smaller than 10 CPI cannot be reliably verified and recognition is inconsistent
Solution Approach 1:
The patent applies local quality by using multiple light sources positioned at different locations (front side and back side of the document) to illuminate specific areas. This creates localized illumination zones that enhance the contrast between characters and background in different regions, enabling reliable verification of small characters (10 CPI or less) that were previously不可靠 with conventional single-source illumination
Solution Approach 2:
The patent transitions from conventional single-angle illumination to multi-dimensional illumination by positioning light sources on both the front and back sides of the personalized document. This multi-angle approach creates multiple reflection paths that enhance character visibility and contrast, solving the reliability issue for small character recognition
2Measurement precision
If conventional imaging methods are used, then characters can be imaged, but reflections from metallic backgrounds and similar colors interfere with verification
Solution Approach 1:
The patent converts the harmful reflections from metallic backgrounds into beneficial contrast enhancement. By using multiple light sources at different positions, the system exploits reflection patterns to create distinct brightness differences between characters and background. The reflections that would normally cause interference are instead used to highlight character edges and improve contrast, eliminating the harmful effect
Solution Approach 2:
The patent introduces multiple light sources as intermediary elements that mediate between the character and the camera. These light sources create controlled illumination patterns that act as intermediaries to enhance contrast and reduce the impact of metallic reflections and color similarities, allowing accurate character verification despite these interfering factors
3Measurement precision
If light is illuminated from specific angles to create contrast, then character visibility improves, but the system complexity increases
Solution Approach 1:
The patent applies universality by designing a multi-light-source system that serves multiple functions simultaneously. The same light sources positioned at different locations perform multiple tasks: illuminating characters, creating contrast, reducing reflections, and enabling verification of small characters. This multi-functionality justifies the increased device complexity by delivering multiple benefits from a single system architecture
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 verifies and recognizes characters of various sizes, including those smaller than 10 CPI, and determines their location and spacing, providing reliable results even with metallic backgrounds or similar colors, enhancing the accuracy and consistency of character verification.
Implementation Method 1
The light reflected from a perimeter of the characters and that reflected from an inner portion of the characters surrounded by the perimeter, in a direction generally perpendicular to the surface of the personalized document, are different in brightness to provide a contrast
Data Source
AI summary
Embodiments of systems and methods for directly reading and verifying characters on a personalized document, are provided. A surface of the personalized document is illuminated independently or simultaneously by first and second light sources. The first light source has a ring shape, surrounds the personalized document in 360 degree, and transmits a grazing incident light to illuminate the surface of the personalized document. An incident light from the second light source is reflected by a beam splitter and illuminates the surface of the personalized document in a direction generally perpendicular to the surface. Light reflected from the surface of the personalized document in a direction generally perpendicular to the surface thereof is collected by a camera.