Infrared Void Pantograph Mark for Document Security

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Solution Overview

Problem

Existing security marks, such as pantograph marks, are fragile and require specific scanner/printer combinations, leading to issues with image quality and fragility, and fail to effectively distinguish originals from copies without degrading image quality.

Innovation Solution

A novel IR void pantograph mark system that uses non-infrared-absorbing colors for both patterns, ensuring they appear the same under ambient light, with one pattern printed as foreground and the other as background, and employs infrared-absorbing ink for the copy to reveal a hidden security element under IR illumination, eliminating dependence on scanner modulation transfer function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UV void pantograph marks are used to create invisible watermarks, then the security mark becomes invisible to the unaided human eye on the original document, but the watermark visibility and image quality degrade due to reliance on scanner MTF and small hole requirements

Engineering Contradiction:

Improvewatermark visibilityVSAvoidimage quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the detection parameter from visible spectrum to infrared spectrum. By using infrared-absorbing and infrared-reflecting colors, the system enables watermark detection through infrared reflectance differences rather than relying on scanner MTF characteristics in the visible spectrum. This allows for larger, more robust mark features that maintain image quality while providing reliable watermark visibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a color-based differentiation system using infrared-absorbing colors (such as black, dark blue, dark green) and infrared-reflecting colors (such as cyan, magenta, yellow, white). This color system creates detectable reflectance differences in the infrared spectrum without affecting visible appearance, enabling robust watermark creation that doesn't rely on small geometric features or scanner-specific characteristics.

Inventive Principle:

Principle #32Color changes

2Reliability

If small holes are used in the pantograph mark to exploit scanner MTF, then the watermark becomes detectable, but the mark becomes more fragile and image quality decreases

Engineering Contradiction:

Improvewatermark detectabilityVSAvoidmark fragility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent transitions from spatial frequency-based detection (relying on small hole patterns and scanner MTF) to spectral-based detection (using infrared absorbance and reflectance properties). This parameter change allows the use of larger, more stable mark features that are not fragile and do not require precise geometric configurations, thereby improving mark stability while maintaining detectability.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If traditional pantograph marks are used, then the security mark can be printed on the original document, but the mark cannot effectively distinguish the original from a copy without degrading image quality

Engineering Contradiction:

Improveoriginal vs. copy distinctionVSAvoidimage quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies different infrared optical properties to different parts of the mark. By using infrared-absorbing colors for the foreground/security element and infrared-reflecting colors for the background, the system creates local quality differences that are detectable in the infrared spectrum. This allows effective original-vs.-copy distinction through infrared imaging without requiring visible degradation or compromising overall image quality.

Inventive Principle:

Principle #3Local quality

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 IR void pantograph mark is more robust, allowing for detailed marks like 2D barcodes and effectively differentiates originals from copies under IR light without degrading image quality, addressing the fragility and compatibility issues of previous systems.

Implementation Method 1

employing an infrared reflectance color and an infrared absorbance color such that the infrared reflectance of the first pattern and the infrared reflectance of the second pattern differ

Methodology Applied

Scientific EffectInfrared radiation reflection: Reflection

Implementation Method 2

select a first pattern that includes one or more non-infrared-absorbing colors, and it will select a second pattern that also includes one or more non-infrared-absorbing colors

Methodology Applied

Scientific EffectInfrared absorption: Absorption (EM radiation)

Data Source

PatentUS10812675B1Verifying document security using an infrared VOID pantograph mark

Publication Date: 2020.10.20 XEROX CORP

AI summary

To generate a security mark, a system prints first and second patterns on a first document using non-infrared absorbing colors. A print engine will receive the substrate and create a copy of the security mark onto a second document. When printing the second document the print engine may use ink of an infrared-absorbing color, such as black, to print a hidden security element of the security mark. When an infrared camera captures a digital image of the second document and the captured image is displayed, the captured image will reveal the hidden security element.