Roll-Fed Print Color Measurement With Optical Patch Alignment

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Solution Overview

Problem

Existing methods for testing the quality of colored printed images on substrates supplied as rolls are prone to errors and lack reproducibility due to manual alignment and measurement processes, which hinder consistent printing quality across the entire production process.

Innovation Solution

A testing device that includes a transport unit for unwinding and rewinding the substrate as a web, coupled with an optical detection device and a color measuring head, allowing precise alignment and automated measurement of color coordinates using a traversing device to determine and output colorimetric values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual alignment and measurement processes are used, then the device complexity is reduced, but the measurement precision and reliability deteriorate due to errors and lack of reproducibility

Engineering Contradiction:
Improvecolor coordinate measurement precisionVSAvoidtesting device structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical alignment and measurement operations with an automated testing device that uses optical detection devices and computer-controlled positioning systems. The color measuring head is automatically positioned over test patches using motorized traversing mechanisms, eliminating manual alignment errors and improving measurement precision and reproducibility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The testing device incorporates self-positioning capabilities where the system automatically locates test patches using optical detection and autonomously performs measurements without requiring manual intervention. The device self-corrects positioning errors and maintains consistent measurement conditions through automated control systems.

Inventive Principle:
Principle #25Self-service

2Productivity

If manual measurement processes are used, then the ease of operation is improved, but the productivity deteriorates due to time-consuming manual alignment and measurement

Engineering Contradiction:
Improvetesting speedVSAvoidoperational simplicity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The testing device enables continuous measurement operations by automatically traversing across multiple test patches without interruption. The system maintains continuous operation by seamlessly moving the color measuring head from one test patch to the next, eliminating the downtime and repositioning delays associated with manual measurement processes.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

Manual measurement operations are replaced by an automated system that uses computer-controlled traversing mechanisms to rapidly position and measure test patches. This substitution dramatically increases testing speed while the automated control software maintains ease of operation through user-friendly interfaces and automatic measurement sequences.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If the substrate is unwound and rewound manually, then the device complexity is reduced, but the manufacturing precision deteriorates because edges cannot be aligned perfectly flush

Engineering Contradiction:
Improvesubstrate edge alignmentVSAvoidtransport unit structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Manual substrate handling and alignment operations are replaced by an automated transport unit with motorized rolling mechanisms. The system automatically feeds the substrate through the testing device, maintains precise tension control, and ensures consistent edge alignment through computer-controlled positioning systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The transport unit incorporates feedback mechanisms that monitor substrate position and tension in real-time. Optical sensors and position encoders provide continuous feedback to the control system, which automatically adjusts rolling forces and positioning to maintain perfect edge alignment throughout the substrate passage.

Inventive Principle:
Principle #23Feedback

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

Enables accurate and reproducible quality control of printed images by ensuring precise alignment and automated measurement, facilitating statistical analysis and reducing errors in the printing process.

Implementation Method 1

at least one optical detection device which is configured to detect at least a portion of the colored printed image on the substrate

Methodology Applied
Scientific EffectLight reflection and absorption: Reflection

Implementation Method 2

The color measuring head is generally designed as a spectrophotometer

Methodology Applied
Scientific EffectSpectrophotometry: Absorption Spectroscopy

Data Source

PatentEP4691778A1Testing device and testing method for a coloured printed image of a printing material provided as a roll
Publication Date: 2026.02.11 BUNDESDRUCKEREI GMBH
  • EP4691778A1 patent drawingFigure 1~2
  • EP4691778A1 patent drawingFigure 3
  • EP4691778A1 patent drawing

AI summary

The invention relates to a testing device for a colored printed image on a substrate (100) provided as a roll (120) and to a method for testing it. The testing device comprises a control unit, a transport unit (200) for unwinding and rewinding the substrate (100) so that it is guided as a web (110) through a working area, and an optical detection unit (500) configured to detect at least a part of the colored printed image on the substrate (100).a traversing device (600) and a color measuring head (700) coupled to the traversing device (600), wherein the traversing device (600) is configured to position the color measuring head (700) at a distance from the surface (115) of the web (110) of the substrate (100), wherein the color measuring head (700) is configured to determine and output color coordinates which indicate a color of the substrate (100) located in a measuring area (705), wherein the control device is configured to determine a position and orientation of the printed image relative to the traversing device (600) based on a part of the printed image detected by the at least one optical detection device (500), and to position the color measuring head (700) at at least one measuring position by means of the traversing device (600) and to determine and output the color coordinates.