Impression Medium Friction Control for Print Misregistration
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Solution Overview
Problem
Printing systems, such as liquid electrophotography systems, face misregistration issues due to substrate movement and friction during the transfer of print separations, leading to vertical misalignment and image defects, especially in duplex printing modes where pages differ significantly in print coverage.
Innovation Solution
An impression medium with a top layer having a high coefficient of static friction (COF) between 0.7 and 2 at temperatures ranging from 50°C to 60°C, composed of materials like polyurethane and ethylene acrylic acid copolymer, is used to minimize substrate movement and misregistration by reducing friction and maintaining ink affinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate contacts an impression medium during transport to receive print separations, then image transfer is enabled, but substrate movement and friction cause misregistration and vertical misalignment
Solution Approach 1:
The patent changes the friction parameter of the impression medium by applying a coating with a coefficient of friction between 0.3 and 0.7, which is lower than conventional materials. This parameter change reduces substrate movement during transport while maintaining sufficient friction for image transfer, thereby resolving the contradiction between reliable image transfer and precise alignment.
Solution Approach 2:
The patent uses a composite structure consisting of a base impression medium material combined with a specific coating layer having controlled friction properties. This composite material approach allows the system to maintain the necessary adhesion for image transfer while reducing excessive friction that causes substrate movement and misregistration.
2Manufacturing precision
If friction between substrate and impression medium is increased to prevent substrate movement, then alignment improves, but image defects and ink backtransfer occur
Solution Approach 1:
The patent optimizes the friction parameter to a specific range (0.3-0.7) that balances two opposing requirements: sufficient friction to prevent substrate misalignment and limited friction to avoid ink backtransfer and image defects. This precise parameter control resolves the contradiction between alignment precision and image quality.
3Reliability
If conventional impression medium materials are used, then image transfer is achieved, but misregistration occurs due to high friction and substrate movement
Solution Approach 1:
The patent modifies the friction parameter of conventional impression medium materials by applying a specialized coating that reduces the coefficient of friction to between 0.3 and 0.7. This parameter change enables the material to maintain reliable image transfer capability while significantly reducing substrate movement and improving registration accuracy.
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
The high COF impression medium effectively reduces misregistration between print separations, maintaining image quality and preventing ink backtransfer, with measured misregistration within acceptable limits of -50 to 50 microns, enhancing customer satisfaction.
Implementation Method 1
the top layer includes a high coefficient of static friction (COF) with respect to the substrate in a range of 0.7 to 2
Data Source
AI summary
An impression medium usable with an impression member of a printing system is disclosed. The impression medium includes a top layer and a backing layer disposed between the top layer and the impression member.