Embedded Color-Correction Inking for High-Speed Print Quality

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Solution Overview

Problem

Flexographic and rotogravure printing machines face issues with ink transfer effectiveness at increased printing speeds, leading to unpredictable decay of printing quality due to environmental variations and ink drying, and existing systems are slow to react to changes in ink composition or printing parameters.

Innovation Solution

An inking system with an inking cylinder and etched cylinder configured to retain ink in a minimal nip area, using sensors to measure printing parameters and adjust ink composition directly in the nip area from two tanks, allowing rapid correction or replacement of ink to maintain optimal print quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If printing speed increases, then productivity is improved, but print quality deteriorates due to reduced ink transfer effectiveness

Engineering Contradiction:
Improveprinting speedVSAvoidprint quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The system dynamically adjusts ink composition by mixing ink from two tanks in variable proportions based on real-time printing conditions. The mixing ratio is continuously adapted to maintain optimal ink transfer characteristics at different printing speeds, resolving the contradiction between speed and quality

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the compositional parameters of the ink by mixing two different inks in configurable proportions. This allows the ink properties to be adjusted to match the printing speed and conditions, maintaining quality across varying productivity levels

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If traditional ink systems are used, then device complexity is low, but response time to ink composition changes is slow

Engineering Contradiction:
Improvesystem simplicityVSAvoidreaction time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The ink supply system is segmented into two separate tanks containing different inks, allowing independent control and rapid mixing. This segmentation enables quick adjustment of ink composition without the delays inherent in single-tank systems, reducing reaction time while maintaining manageable complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Two different inks are pre-loaded into separate tanks, ready for immediate mixing in the required proportions. This preliminary preparation allows the system to respond rapidly to changing printing conditions without delay, as the components are already in position

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If ink is added to correct composition, then printing parameters can be adjusted, but the corrected ink is not in direct contact with the printing roller until current ink is consumed

Engineering Contradiction:
Improveprinting parameter controlVSAvoidtime to correct ink availability
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system continuously mixes and supplies corrected ink directly to the printing roller through the nip area, eliminating interruptions. The mixing action continues uninterrupted as the printing roller rotates, ensuring constant availability of correctly composed ink without waiting for current ink consumption

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The nip area between the inking roller and printing roller serves as an intermediary zone where corrected ink is directly applied and mixed with the running ink supply. This intermediary mechanism allows immediate contact of corrected ink with the printing roller, eliminating the delay of waiting for current ink consumption

Inventive Principle:
Principle #24Intermediary (Mediator)

4Stability of the object's composition

If the whole volume of ink is heated to control temperature, then temperature stability is improved, but the process takes time

Engineering Contradiction:
Improveink temperature stabilityVSAvoidheating time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

Instead of heating the entire ink volume, the system applies thermal control locally to the ink in the nip area and the mixing region. This localized approach maintains ink temperature stability where it matters most - at the printing interface - while significantly reducing the time required compared to heating the whole volume

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3684617B1Inking system with embedded colour correction
Publication Date: 2026.03.11 BOBST FIRENZE
  • EP3684617B1 patent drawingFigure 1
  • EP3684617B1 patent drawingFigure 2
  • EP3684617B1 patent drawingFigure 3

AI summary

The present invention concerns an inking system for a flexographic or a rotogravure press. The inking system uses a very small amount of ink (10) coupled with an ink source (6) made of two tanks (62) with two different inks. Thanks to feedback given by measuring the output directly on the printed support, the system mixes the ink in the optimal proportions to ensure an optimal printing quality at any time. It can compensate any effect due to environmental changes like the humidity or the temperature. This system, coupled with a seven colours press allows for the replacement of spot colours in most cases therby saving time and costs.