2-D Image Correction for Thermal Ghosting in Digital Printers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional lithographic printing systems face challenges in accommodating high-speed variable data printing due to thermal ghosting issues, where heat signatures from previous prints cause image quality artifacts on subsequent prints due to non-uniform imaging member surface temperatures.

Innovation Solution

A method and apparatus for predicting temperature increases on a rotatable imaging member surface, creating a temperature map, aligning digital image information with this map, and modifying gray levels to adjust marking material density, thereby preventing ghosting by rendering corrected images that compensate for temperature differences across the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-speed variable data printing is implemented using digital offset printing systems, then printing speed and productivity are improved, but thermal ghosting artifacts appear on subsequent prints due to non-uniform imaging member surface temperatures

Engineering Contradiction:

Improveprinting speedVSAvoidimage quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary temperature mapping of the imaging member surface before printing to identify thermal variations. This advance knowledge allows the system to pre-correct image data by adjusting gray levels in areas that will be affected by thermal ghosting, thereby preventing image quality degradation while maintaining high-speed printing capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts gray level parameters in the image data based on detected temperature variations across the imaging member surface. By modifying the density marking material in specific regions according to the temperature map, the system compensates for thermal effects and maintains consistent image quality across multiple high-speed prints

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the imaging member surface temperature is allowed to vary during high-speed printing, then printing efficiency is improved, but thermal ghosting causes image quality artifacts on subsequent prints

Engineering Contradiction:

Improveprinting efficiencyVSAvoidthermal ghosting artifacts

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system converts the harmful thermal variations into useful information by mapping the temperature distribution across the imaging member surface. This temperature map is then used to guide gray level adjustments in the image data, transforming the previously harmful thermal ghosting effect into a correctable parameter that actually improves image consistency

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system implements a feedback mechanism where temperature information from the imaging member surface is continuously monitored and used to adjust subsequent image rendering. The temperature map serves as feedback that informs real-time corrections to the digital image data, ensuring that thermal variations do not degrade image quality

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

This approach effectively mitigates thermal ghosting artifacts by ensuring consistent image quality across multiple prints, maintaining the intended digital image appearance despite temperature variations on the imaging member surface.

Implementation Method 1

An imaging system then evaporates regions of the fountain solution layer in an image area by exposure to a focused radiation source (e.g., a laser light source, high power laser) to form pockets

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

The inventors have found that when printing, heat signatures (e.g., thermal ghosting) from images printed on previous imaging member surface revolutions may be observed on subsequent revolutions

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11148414B12-D image based correction of thermal ghosting in a digital printer

Publication Date: 2021.10.19 GENESEE VALLEY INNOVATIONS LLC

AI summary

An image based correction system compensates for the image quality artifacts induced by thermal ghosting. With thermal ghosting directly tied to previous image content, a feed forward control system predicts the thermal ghosting artifact based on the images previous printed and generates an open loop, 2-D correction to the gray-level image that mitigates the undesirable ghosting artifacts. For example, the correction system compensates for the thermal ghosting by making the current digital image “lighter” in areas that will be imaged onto warmer blanket regions, thereby cancelling out TRC differences between different temperature regions.