Digital Offset Inking System Ghosting Prevention

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Solution Overview

Problem

In digital offset printing, traditional inking systems suffer from ghosting due to uneven ink layers and the mixing of fountain solution with ink, which leads to lighter image areas and negative ink thickness patterns on the form roll, causing print quality issues.

Innovation Solution

The implementation of an inking system that includes a cleaning mechanism to separate ink from fountain solution on the form roll, using a cleaning blade to remove leftover ink and fountain solution, and a fountain solution removal system to process the mixture, ensuring the ink supplied is substantially free of fountain solution, thereby preventing ghosting and maintaining print quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional inking systems are used in digital offset printing, then the inking process can be performed with standard equipment, but ghosting occurs due to uneven ink layers and fountain solution contamination

Engineering Contradiction:

Improveinking system implementationVSAvoidprint quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The inking system is divided into separate functional sections: a first inking section that applies ink to the entire surface of the imaging plate, and a second inking section that selectively applies ink only to non-image areas. This segmentation prevents fountain solution contamination in the second section, eliminating ghosting while maintaining ease of implementation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different inking characteristics are applied to different areas of the imaging plate. The first inking section provides uniform coverage across the entire surface, while the second inking section provides selective inking only where needed (non-image areas), ensuring high print quality without ghosting artifacts

Inventive Principle:

Principle #3Local quality

2Reliability

If fountain solution is applied to the imaging plate to prevent ink adhesion, then ink rejection is improved, but fountain solution mixes with ink and causes emulsification and ghosting

Engineering Contradiction:

Improveink rejectionVSAvoidfountain solution contamination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The inking process is segmented into two distinct sections: the first inking section operates where fountain solution is present and allows mixing, while the second inking section operates free of fountain solution contamination. This ensures reliable ink rejection in the first section while preventing harmful contamination in the second section

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The imaging plate surface acts as an intermediary between the fountain solution and the ink application processes. By carefully controlling the sequence and location of ink application relative to fountain solution presence, the system achieves reliable ink rejection where needed while preventing contamination in critical areas

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If ink is applied uniformly across the entire imaging plate surface, then complete coverage is achieved, but ink is wasted in non-image areas and ghosting occurs

Engineering Contradiction:

Improveink coverageVSAvoidink waste

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The inking operation is segmented into two phases: initial uniform application across the entire surface followed by selective application only to non-image areas. This ensures complete coverage is achieved initially while minimizing subsequent ink waste by limiting further application to areas that actually require ink

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first inking section performs a preliminary uniform ink application across the entire imaging plate surface before the second inking section operates. This preliminary action ensures complete coverage is established, and subsequent selective inking only adds ink where necessary, reducing overall ink waste

Inventive Principle:

Principle #10Preliminary action

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 solution ensures a uniform ink layer is applied to the digital imaging member, eliminating ghosting and maintaining print quality by removing residual fountain solution from the ink, resulting in consistent and high-quality image transfers.

Implementation Method 1

contacting a surface of the form roll with a cleaning blade, whereby the fountain solution is removed from the form roll

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

separating the ink from the fountain solution

Methodology Applied

Scientific EffectPhase separation: Phase Change

Data Source

PatentUS8893616B2Ghost-free inking methods, apparatus, and systems with reduced fountain solution contamination

Publication Date: 2014.11.25 GENESEE VALLEY INNOVATIONS LLC

AI summary

A digital offset inking system includes an ink supply, a soft transfer roll, and a hard form roll. A cleaning blade cleaning ink and fountain solution from the surface of the hard form roll that is leftover after transferring ink to a digital imaging member. A fountain solution removal system processes the ink to remove the fountain solution from the ink. The processes ink is resupplied to the inking system for transfer to the digital imaging member.