Evaporative Dampening Fluid Thickness Control in Digital Lithography

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Solution Overview

Problem

Existing lithographic and offset printing systems face challenges in achieving precise and uniform dampening fluid layer thickness, leading to issues like ribbing instability, contamination, and cavitation, which affect the quality of printed images, especially in variable data printing where high viscosity and tacky nature of inks complicate the process.

Innovation Solution

A system employing an evaporative thickness control subsystem that uses controlled gas flow to evaporate a portion of the initially deposited dampening fluid, allowing for precise layer thickness control through real-time feedback mechanisms, ensuring a uniform and desired thickness of the dampening fluid layer on the reimageable surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a dampening fluid layer is applied to the reimageable surface using conventional methods, then the surface is prepared for lithographic printing, but the layer thickness is non-uniform leading to ribbing instability and print quality issues

Engineering Contradiction:

Improvedampening fluid layer thickness uniformityVSAvoidprint quality stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent employs a feedback control system where a sensor detects the actual dampening fluid layer thickness and sends signals to a controller that adjusts the evaporation rate accordingly. This closed-loop feedback mechanism ensures the layer thickness remains within the desired range, preventing ribbing instability and ensuring consistent print quality across the entire print run.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes physical parameters including gas flow rate, temperature, and humidity levels to control the evaporation process. By adjusting these parameters in real-time based on feedback, the system achieves precise control over dampening fluid layer thickness, transforming a non-uniform deposition process into a controlled, uniform thin film formation process.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the dampening fluid layer thickness is not precisely controlled, then the printing process can proceed without additional control mechanisms, but artifacts such as ribbing instability and cavitation occur affecting image quality

Engineering Contradiction:

Improvecontrol system simplicityVSAvoidprint artifacts

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The feedback control system continuously monitors dampening fluid layer thickness and adjusts evaporation parameters to prevent the formation of print artifacts. By detecting deviations from the target thickness range and correcting them in real-time, the system eliminates ribbing instability and cavitation without requiring overly complex mechanical control mechanisms.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical control methods with an evaporative control system using gas flow and thermal fields. Instead of mechanically adjusting the dampening fluid application, the system uses controlled evaporation through gas flow rate and temperature management, substituting mechanical complexity with controllable physical field parameters.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If variable data printing is implemented with high viscosity inks, then digital printing capability is achieved, but the tacky nature of inks creates high surface adhesion forces complicating manipulation

Engineering Contradiction:

Improvevariable data printing capabilityVSAvoidink manipulation difficulty

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent modifies the physical state and flow characteristics of high viscosity inks by controlling temperature and applying vacuum. These parameter changes reduce the effective viscosity and surface adhesion forces during the transfer process, enabling digital variable data printing with lithographic inks while maintaining ease of manipulation through controlled physical conditions rather than mechanical force.

Inventive Principle:

Principle #35Parameter changes

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 enables precise and uniform dampening fluid layer thickness, reducing artifacts and improving print quality by dynamically controlling the evaporation process, thus accommodating variable data printing and reducing costs per copy across different print run lengths.

Implementation Method 1

A system employing an evaporative thickness control subsystem that uses controlled gas flow to evaporate a portion of the initially deposited dampening fluid

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS8950322B2Evaporative systems and methods for dampening fluid control in a digital lithographic system

Publication Date: 2015.02.10 GENESEE VALLEY INNOVATIONS LLC

AI summary

A system and corresponding methods are disclosed for controlling the thickness of a layer of dampening fluid applied to a reimageable surface of an imaging member in a variable data lithography system. Following deposition of the dampening fluid layer, a gas is passed over a region of the fluid layer prior to pattern forming. The gas causes a controlled amount of the dampening fluid layer to evaporate such that the remaining layer is of a desired and controlled thickness. Among other advantages, improved print quality is obtained.