Fountain Solution Thickness Measurement via Optical Properties
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Solution Overview
Problem
Conventional digital offset printing systems lack an accurate method to quantify the thickness of the fountain solution layer, which is critical for maintaining image quality, as insufficient or excessive fountain solution can lead to distorted prints.
Innovation Solution
A fountain solution thickness measurement system utilizing the optical properties of a phase-changed film, where the fountain solution is transferred to an engineered surface with known roughness, evaporated or frozen, and measured for opacity using an emissive light source and sensor, allowing for precise control of the deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fountain solution thickness is not measured accurately, then image quality cannot be controlled, but implementing measurement adds system complexity
Solution Approach 1:
The patent uses an intermediary engineered surface with known optical properties as a substrate for the fountain solution film. This mediator allows the measurement system to characterize the fountain solution thickness indirectly through optical transmission measurements, avoiding the need for direct complex measurement of the thin liquid film itself.
Solution Approach 2:
The patent replaces direct physical measurement methods with optical measurement. By using light transmission through the fountain solution film on an engineered surface, the system substitutes complex mechanical or direct physical sensing with simpler optical detection, reducing overall system complexity while maintaining measurement precision.
2Manufacturing precision
If fountain solution layer is made thinner to improve image sharpness, then ink control improves, but measurement difficulty increases
Solution Approach 1:
The engineered surface acts as an intermediary that provides a stable, known optical baseline. This allows the measurement system to detect very thin fountain solution films by comparing light transmission against the known properties of the engineered surface, making measurement of ultra-thin films feasible.
Solution Approach 2:
The patent changes the measurement parameter from direct physical thickness measurement to optical transmission measurement. By measuring how light transmits through the fountain solution film on the engineered surface, the system can accurately characterize very thin films that would be difficult to measure with direct physical methods.
3Reliability
If more fountain solution is applied to prevent ink invasion, then image distortion from ink spread is reduced, but excess fountain solution enters image area and causes distortion
Solution Approach 1:
The patent implements a feedback control system where the optical measurement of fountain solution thickness on the engineered surface provides real-time information about the actual film thickness. This feedback allows the system to adjust fountain solution application to maintain optimal thickness, preventing both ink invasion and excess solution entry into image areas.
Solution Approach 2:
The patent replaces operator experience-based control with automated optical measurement and control. The optical detection system continuously monitors fountain solution thickness and provides objective data for control decisions, eliminating the subjectivity and inconsistency of operator judgment while improving ease of operation.
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
Enables accurate measurement and control of the fountain solution thickness, ensuring consistent image quality by maintaining the layer within optimal thickness ranges, preventing ink invasion or excess fountain solution issues.
Implementation Method 1
uses an emissive light source to pass light along a path from the source through the engineered surface; receiving light passing through the engineered surface at a light detector
Implementation Method 2
evaporated or frozen into a solid state
Implementation Method 3
evaporated or frozen into a solid state
Data Source
AI summary
According to aspects of the embodiments, there is provided a method of measuring the amount of fountain solution employed in a digital offset lithography printing system. Fountain solution thickness is measured using a glass roll at a lower temperature than the fountain solution. The lower temperature causes the fountain solution to undergo a change in state and in a solid state the fountain solution crystalizes and changes roll opacity with the thickness of the film. When radiated with a light source the opacity is continuously measured through the surface of the roller. The thickness of the crystallized fountain solution can then be determined via the opacity level increase by the crystallization and the impact to the opacity on the glass roll.