Digital Printing System with Intermediate Transfer Member
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Solution Overview
Problem
Current digital printing systems face challenges in achieving high-quality duplex printing due to inkjet printing limitations, such as substrate wetting and image quality issues, especially when printing on uncoated paper, and the complexity of changing between simplex and duplex modes.
Innovation Solution
A digital printing system with two independently operable printing towers and a perfecting mechanism that allows for duplex printing by reversing substrate sheets between towers, enabling each tower to print on either side, and an automated print bar positioning system for efficient mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If inkjet printing is used directly onto the substrate, then the printing process is simple, but the substrate becomes excessively wet causing cockling and making duplex printing difficult
Solution Approach 1:
The patent introduces an intermediate transfer member (ITM) as a mediator between the inkjet print head and the substrate. The ITM receives the ink image from the print head, allows it to dry, and then transfers it to the substrate. This intermediary approach prevents direct wetting of the substrate while maintaining the simplicity of inkjet printing.
Solution Approach 2:
The printing process is segmented into distinct stages: image formation on the ITM, drying of the ink image on the ITM, and transfer to the substrate. This segmentation allows the drying process to occur separately before substrate contact, eliminating the wetting problem while keeping the overall system relatively simple.
2Manufacturing precision
If coated substrates are used to prevent ink penetration, then image quality improves, but the substrate surface remains wet requiring additional drying steps
Solution Approach 1:
The ink image is formed and dried on the intermediate transfer member before being transferred to the substrate. This preliminary drying action ensures the substrate is not wetted by the ink, eliminating the need for additional drying steps after substrate printing.
3Device complexity
If a single printing tower is used for simplex printing, then the system is simple, but changing to duplex mode requires complex reconfiguration
Solution Approach 1:
The system employs a dynamically reconfigurable printing system where the single printing tower can be repositioned or reconfigured to operate in either simplex or duplex mode. The print head and associated components can be moved between different operational configurations, allowing mode changeover without requiring a completely different system architecture.
Solution Approach 2:
The system is designed to periodically switch between simplex and duplex operational modes through automated reconfiguration sequences. The printing tower can be repositioned to different configurations as needed, enabling flexible mode changes while maintaining system simplicity.
4Manufacturing precision
If the print head is positioned close to the substrate for high resolution, then image quality improves, but the distance variation causes poor image quality
Solution Approach 1:
The intermediate transfer member serves as a stable intermediary surface that maintains a consistent distance from the inkjet print head. By printing onto the ITM rather than directly onto the substrate, the system achieves reliable positioning and consistent image quality without the distance variation problems that occur with substrate irregularities.
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 high-speed duplex printing with improved image quality on both sides of the substrate without the need for coated papers, reducing wetting issues and simplifying the changeover process between simplex and duplex operations.
Implementation Method 1
an image forming system serving under digital control to direct droplets of a water-based ink onto the intermediate transfer member to form an ink image
Implementation Method 2
a drier for drying the ink image while it is being transported by the intermediate transfer member to form a residue film
Implementation Method 3
an impression station at which the residue film is impressed onto a sheet substrate
Data Source
AI summary
A digital printing system is disclosed having two independently operable printing towers arranged in series such that a substrate sheet passes sequentially through both printing towers, and in which a perfecting mechanism is provided between the two towers to reverse each substrate sheet during transfer from the first printing tower to the second printing tower, the perfecting mechanism being selectively operable to enable the second tower to print either on the same side of each substrate sheet as the first tower or on the opposite side of each substrate sheet. As well as allowing a duplex mode, the system provides a higher speed simplex mode during which different separations of the same image are printed by the two towers.