Optical Reader for Perforated Documents Using Dual-Wavelength Light
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Solution Overview
Problem
Existing optical sensors are unable to reliably detect micro-perforations in documents due to their small size and low contrast with the surrounding areas, and are not capable of distinguishing real holes from printed images, leading to difficulties in verifying the authenticity of documents like cheques and banknotes.
Innovation Solution
An optical reading device that combines a Contact Image Sensor (CIS) with a lighting system using different wavelengths of light, allowing for simultaneous detection of printed and perforated areas by switching between reflective and backlight modes to differentiate between the two, and utilizing high-resolution sensors to process images and ensure accurate correlation of printed and perforated codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a direct lighting system with detector on one side and lighting device on the opposite side is used to detect holes, then the presence/absence of holes can be detected, but the system does not have the necessary resolution for reading perforated alphanumerical codes
Solution Approach 1:
The patent segments the detection task into two distinct modes: a first detection mode using a first light source and first detector for hole presence/absence detection, and a second detection mode using a second light source and second detector for reading perforated codes. This segmentation allows each detection system to be optimized for its specific function, resolving the contradiction between hole detection capability and code reading resolution.
Solution Approach 2:
The patent creates a universal reading device that can perform multiple functions: detecting hole presence/absence and reading perforated alphanumerical codes. By integrating both detection capabilities into a single device with multiple light sources and detectors, the system achieves multi-functionality without sacrificing the specialized performance needed for each task.
2Reliability
If separate reading devices for holes and printed surfaces are provided, then both can be detected accurately, but the size, complexity, and cost of the machine increases unacceptably
Solution Approach 1:
The patent merges the functions of separate reading devices into a single integrated reading device. By combining multiple light sources (first light source for hole detection, second light source for code reading) and multiple detectors (first detector, second detector) into one device, the system achieves reliable detection of both holes and printed codes while avoiding the size and complexity penalties of completely separate systems.
Solution Approach 2:
The reading device is designed as a universal system capable of performing both hole detection and code reading functions. This multi-functionality is achieved through intelligent integration of different detection mechanisms within a single device architecture, reducing overall system complexity while maintaining detection accuracy.
3Measurement precision
If a CIS sensor is used to scan the surface of documents, then surface printing can be detected, but the sensor is unable to distinguish real holes from merely the image of a hole printed on the surface
Solution Approach 1:
The patent introduces light as an intermediary to verify hole authenticity. The first light source illuminates the document from one side, and the first detector on the opposite side detects whether light passes through. This optical intermediary allows the system to distinguish real holes (which transmit light) from printed hole images (which block light), resolving the reliability issue.
Solution Approach 2:
The system utilizes optical property changes - specifically light transmission vs. light blocking - to differentiate between real holes and printed images. Real holes allow light to pass through to the detector, while printed images block the light. This optical contrast provides reliable hole authenticity verification.
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 device enables fast, reliable, and cost-effective detection of both printed and perforated areas in documents, preventing fraudulent activities by ensuring the accurate association of printed and perforated codes, and reducing the complexity and size of the scanning machine.
Implementation Method 1
a first light source arranged to emit light towards a first detector arranged on the opposite side
Implementation Method 2
a second light source arranged to emit a strip of light towards the surface of the document, and a second detector arranged to acquire an image of the surface of the document
Data Source
Figure 1~2
Figure 3~5
AI summary
An optical reading device for documents endowed with printed and/or perforated surfaces, with at least one CIS (15) equipped with light emitters (19) and detectors (20) and positioned, on one side of a path for the movement of a document with respect to the sensor, for reading, by means of reflection, one side of the document, and means (18, 16, 116, 216, 19) of sending light towards the sensor, arranged in a frontal position with respect to the sensor (15), on the other side of the path for the movement of a document for lighting the sensor (15) through any holes which may be present in the document. Processing means receive the signals from the sensor (15) and obtain images of the perforated and/or printed areas in the document. A detecting method is also described.