Media-Path Extender for Web Printer Drying
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Solution Overview
Problem
Current printing technologies face limitations in drying ink on web-fed printers, leading to reduced speed, increased power consumption, and potential damage to media due to active dryers, which also cause registration issues and thermal shock.
Innovation Solution
The implementation of a media-path extender with rotatable members that allows for selective transportation along a bypass or extension media path, providing additional drying time without increasing power consumption or footprint, and using convection to reduce thermal shock, thereby improving registration and media handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If active dryers are used to dry ink on web-fed printers, then drying speed is improved, but power consumption increases significantly
Solution Approach 1:
The patent extends the media path length between printing stations to provide additional drying time before the web reaches the next printing station. This preliminary drying action allows ink to dry naturally through evaporation and absorption without requiring high-power active dryers, thereby reducing power consumption while maintaining acceptable drying speed
Solution Approach 2:
The invention enables the web itself to perform the drying function by extending its travel distance through the printing press. The natural evaporation and absorption processes occur during the extended media path traversal, allowing the system to dry ink without additional energy-intensive drying equipment
2Speed
If active dryers are used to dry ink, then drying effectiveness is improved, but floor space requirements increase
Solution Approach 1:
Instead of adding drying equipment in the vertical or lateral dimensions (which would increase footprint), the patent extends the media path in the longitudinal dimension - the direction of web travel. This allows additional drying time to be achieved by making the web travel farther along the existing press length, utilizing the longitudinal space already available in the printing press
3Speed
If high-thermal-flux drying is used, then drying speed is improved, but media damage occurs due to paper blistering
Solution Approach 1:
The patent uses periodic or intermittent heating zones along the extended media path rather than continuous high-thermal-flux drying. The web passes through multiple shorter heating sections spaced along the extended path, allowing gradual moisture removal without subjecting the media to intense concentrated heat that would cause blistering or burning
Solution Approach 2:
The invention changes the thermal parameters by distributing heating over a longer distance and time period. Instead of high temperature over a short duration, the system uses lower temperature over an extended duration, fundamentally altering the thermal exposure profile to prevent media damage while achieving adequate drying
4Speed
If drying stages are added between marking units, then ink drying is improved, but color-to-color mis-registration occurs
Solution Approach 1:
The extended media path provides preliminary drying action between printing stations, allowing ink to set and bond to the substrate before subsequent printing operations. This preliminary drying prevents ink transfer and misregistration issues that would occur if the web were repositioned or handled after high-heat drying
Solution Approach 2:
The extended media path acts as an intermediary zone between printing stations, providing a controlled environment for gradual ink drying. This intermediary drying zone allows ink to dry uniformly without the thermal shock that causes dimensional changes and registration problems
5Productivity
If printing speed is increased, then productivity is improved, but ink drying time is insufficient
Solution Approach 1:
The patent compensates for reduced drying time at higher speeds by extending the media path length in the longitudinal dimension. The web travels a longer distance between printing stations, providing additional drying time without reducing printing speed, thereby maintaining both productivity and adequate drying
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 solution enables faster printing speeds over a wider range of substrates with improved color-to-color and duplex registration, reduced thermal shock, and minimized media damage, while maintaining low power consumption and footprint.
Implementation Method 1
using convection to reduce thermal shock
Data Source
AI summary
Apparatus for drying media in a printer includes first and second successive printing stations with a first rotatable member that contacts the wet side of the media between them. Each prints on one side of the media. A media-path extender between the first printing station and the first rotatable member includes a dry-side rotatable member and a wet-side rotatable member around which the media path passes in that order. An extension media path is defined from the first printing station past the dry-side member, the wet-side member, and the first rotatable member, in that order, to the second printing station. The printer selectively transports the media either along a bypass media path or along the extension media path. The wet-side member is farther past the first printing station than is the first rotatable member.