Fog Development for Digital Offset Printing
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Solution Overview
Problem
Variable data lithography systems face high power consumption due to the need for high power lasers to evaporate fountain solutions, making them inefficient and costly, especially when trying to achieve wide cross-process widths and high speeds.
Innovation Solution
The system employs fog development of a charge image created electrographically, using a developer unit to form a fountain solution image without the need for high power lasers, which is then transferred to a print substrate or a silicone surface for inking and further transfer to a final substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high power lasers are used to evaporate fountain solution, then imaging speed can be maintained, but power consumption becomes excessively high
Solution Approach 1:
The patent replaces the thermal field (laser evaporation) with an electrostatic field system. Instead of using high power lasers to evaporate fountain solution, the invention uses electrostatic charging of the imaging surface followed by attraction of charged fog droplets, substituting thermal energy with electrical energy for more efficient operation
Solution Approach 2:
The invention changes the fundamental parameter of image formation from thermal evaporation to electrostatic attraction. By charging the imaging surface and using electrostatically charged fog droplets, the system achieves image formation through electrical parameter changes rather than thermal parameters, reducing power consumption
2Manufacturing precision
If high power lasers are used to create fountain solution images, then imaging precision can be achieved, but system cost increases
Solution Approach 1:
The patent uses a conventional ROS imager to create the electrostatic latent image instead of expensive specialized laser imaging systems. The ROS imager is a more common, less expensive component that can be adapted for electrostatic imaging, reducing system cost while maintaining imaging precision through the electrostatic development process
Solution Approach 2:
The invention introduces fog droplets as an intermediary medium between the electrostatic latent image and the final visible image. The charged fog droplets serve as the developing agent that makes the latent electrostatic image visible, replacing the need for expensive laser-based direct imaging systems
3Use of energy by moving object
If conventional ROS imagers are used instead of lasers, then power consumption decreases, but ability to evaporate fountain solution at high speed is reduced
Solution Approach 1:
The patent replaces the evaporation mechanism with an electrostatic attraction mechanism. Instead of using thermal energy to evaporate fountain solution, the system uses electrostatically charged fog droplets that are attracted to oppositely charged regions on the imaging surface, enabling high-speed imaging without high power consumption
Solution Approach 2:
The invention changes the state and properties of the fog droplets by charging them electrostatically. This parameter change allows the droplets to be controlled and deposited precisely on the imaging surface at high speeds, achieving both low power consumption and high productivity
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 significantly reduces power consumption and increases printing speed while lowering system costs and enhancing the longevity of printing plates by eliminating the reliance on high power laser imaging.
Implementation Method 1
a developer unit proximate the imaging member and adapted to form a fog of charged droplets that are attracted to the electrostatic charge image to form the fountain solution image on the imaging member
Data Source
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AI summary
Ink-based digital printing systems useful for ink printing include a photoreceptor layer configured to receive a layer of liquid immersion fluid. The liquid immersion fluid includes dampening fluid, dispersed gas particles, and charge directors that impart charge to the solid particles. The photoreceptor surface is charged to a uniform potential, and selectively discharged using an ROS according to image data to form an electrostatic latent image. The charged liquid immersion fluid adheres to portions of the photoreceptor surface according to the electrostatic latent image to form a fountain solution image. The fluid portion of the fountain solution image can be partially transferred to an imaging member and/or transfer member to form a dampening fluid image, either or both of which may be electrically biased. The dampening fluid image is inked on the transfer member, and the resulting ink image transferred to a print substrate.