Fountain Solution Thickness Control via Printed Image Delta-E Measurement
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Solution Overview
Problem
Digital printing processes are sensitive to the amount of fountain solution applied to the imaging member blanket, making it difficult to measure and control the optimal thickness, which affects print quality due to either excessive or insufficient solution deposition.
Innovation Solution
A method is introduced to control fountain solution thickness by measuring the ΔE of printed images on a substrate, comparing it to a predefined target ΔE, and adjusting the fountain solution dispense rate based on this measurement to maintain optimal printing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fountain solution dispense rate is increased, then coverage of imaging member surface is improved, but measurement of actual thickness becomes more difficult
Solution Approach 1:
The patent uses printed image characteristics (ΔE measurement) as an intermediary indicator to indirectly measure fountain solution thickness. Instead of attempting to directly measure the thin fountain solution layer on the imaging member, the system measures the effect of the fountain solution on the printed image quality, which serves as a proxy for thickness control.
Solution Approach 2:
The patent replaces direct physical measurement of fountain solution thickness with an optical/electronic measurement system that measures ΔE (color difference) of printed images. This substitution allows for non-contact, real-time measurement that is more practical than direct thickness measurement.
2Manufacturing precision
If fountain solution thickness is not properly controlled, then print quality deteriorates, but direct measurement capability is lacking
Solution Approach 1:
The patent implements a feedback control system where ΔE measurements of printed images are used to determine whether fountain solution thickness is within the acceptable range. The system continuously monitors print quality and adjusts fountain solution application accordingly, creating a closed-loop control mechanism that maintains precision without requiring direct thickness measurement.
Solution Approach 2:
The patent changes the measurement parameter from direct physical thickness to optical property (ΔE color difference). By measuring the optical characteristics of the printed image instead of the physical dimension of the fountain solution layer, the system achieves precise indirect measurement that correlates with print quality.
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 allows for real-time adjustments to ensure a consistent and optimal fountain solution thickness, improving print quality by preventing issues such as background contamination or incomplete ink transfer.
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
Implementation Method 2
measuring ΔE of an image printed at a region of a printed substrate, with the ΔE at the region being a measure of change in visual perception between the region and a non-printed area
Data Source
AI summary
Examples of the preferred embodiments use printed content (e.g., halftones, difference in grayscale or darkness) to determine thickness of fountain solution applied by a fountain solution applicator on an imaging member surface and/or determine image forming device real-time image forming modifications for subsequent printings. For example, in real-time during the printing of a print job, a sensor may measure halftones or grayscale differences between printed content and non-printed content of a current printing on print substrate. Based on this measurement of printed content output from the image forming device, the image forming device may adjust image forming (e.g., fountain solution deposition flow rate, imaging member rotation speed) to reach or maintain a preferred fountain solution thickness on the imaging member surface for subsequent (e.g., next) printings of the print job.