Watermark Position Correction for Security Paper Production
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Solution Overview
Problem
The production of endless paper webs for security and value documents faces challenges due to large positional tolerances in watermark marks, affecting the accuracy of subsequent processing steps.
Innovation Solution
A method that involves producing an endless paper web with watermarks, detecting the positions of these marks, generating colored identification marks with smaller positional deviations, and using these marks for more accurate further processing steps, including the application of security features and position correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If watermark marks are used for controlling further processing steps, then the production process remains simple and inexpensive, but the positional accuracy of subsequent processing steps deteriorates due to large positional tolerances
Solution Approach 1:
The system segments the marking function into two distinct stages: first, watermark marks are applied during paper production for basic control; second, identification marks are applied in a subsequent marking step using detected watermark positions as reference. This segmentation allows each marking type to serve its specific purpose optimally.
Solution Approach 2:
The watermark marks are applied in advance during paper production as preliminary control elements. Their positions are then detected and used as a basis for calculating more accurate mark positions, enabling subsequent precise positioning without requiring the watermarks themselves to be highly accurate.
Solution Approach 3:
The detected watermark positions serve as an intermediary reference system. By detecting these positions and calculating offset values, the system creates a bridge between the simple watermark application and the precise identification mark application, allowing accurate positioning without complex direct marking systems.
2Ease of operation
If identification marks are applied using a touching method, then the marking process is straightforward, but the device complexity increases and integration into existing systems becomes difficult
Solution Approach 1:
The patent replaces mechanical touching marking methods with non-contact marking technologies such as inkjet printing or laser marking. This substitution eliminates the need for physical contact between the marking device and paper web, reducing mechanical complexity while maintaining marking capability.
Solution Approach 2:
Inkjet printing technology uses pneumatic and hydraulic principles to deposit ink droplets non-contactly onto the moving paper web. This allows precise marking without mechanical contact, simplifying device integration into existing paper production lines.
3Manufacturing precision
If laser-cut marks are used for identification, then precise marking is achieved, but harmful factors are generated requiring smoke extraction and scrap removal systems
Solution Approach 1:
The patent converts the harmful effect of laser cutting (smoke and scraps) into a beneficial non-contact marking process. By using inkjet or laser marking instead of laser cutting, the system achieves precise identification without generating harmful byproducts, eliminating the need for smoke extraction and scrap removal systems.
Solution Approach 2:
Inkjet marking uses disposable ink droplets that are applied and immediately fixed, avoiding the generation of persistent scraps or waste materials. The ink is consumed in the marking process itself without creating removable byproducts.
4Manufacturing precision
If multiple watermark marks are provided per paper sheet, then better position control is achieved, but the production complexity and cost increase
Solution Approach 1:
The system applies partial action by providing at least one watermark per paper sheet perimeter during production, which is sufficient for the detection and calculation process. Additional watermarks can be added if needed, but the minimum requirement achieves the necessary precision without excessive complexity.
Solution Approach 2:
The watermark marks serve multiple functions: they act as control marks during paper production, serve as reference points for position detection, and provide the basis for calculating accurate identification mark positions. This multi-functionality eliminates the need for separate marking systems.
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 enhances the positional accuracy of subsequent processing steps, allowing for precise alignment and application of security features, reducing errors and improving the quality of the final products.
Implementation Method 1
it has proven useful to apply the identification marks in step d) using the inkjet method
Implementation Method 2
The laser-sensitive feature substances are locally modified by laser exposure, for example colored and preferably blackened
Implementation Method 3
laser-sensitive feature substances can already be introduced into the paper in step a)... The laser-sensitive feature substances are locally modified by laser exposure
Implementation Method 4
detecting the positions of two or more watermark marks on the endless paper web
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a method for producing a continuous paper web (10) for the production of security and value documents, comprising the following method steps: a) generating a continuous paper web (10) on a vat machine, wherein the paper web is divided into a plurality of equal paper sheets (12) extending transversely to the continuous longitudinal direction, and providing at least one paper sheet (12) per vat circumference of the vat with at least one water mark (20) for controlling further processing steps, wherein certain position deviations exists between the positions of the water marks (20) of the paper sheets, b) detecting the positions of two or more water marks (20) on the continuous paper web (10), c) determining mark positions having lesser position deviations than the position deviations of the detected water marks (20), d) generating colored identification marks (22) at certain mark positions of the paper web (10), and e) detecting the positions of the generated identification marks (22) and carrying out a further processing step using the detected positions of the identification marks (22).