Web Transport Jogging to Prevent Print Area Deformation
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Solution Overview
Problem
In web printing systems, prolonged stationary periods in the ready-to-print mode can lead to deformation of the web due to pressure marks or heat-induced shrinkage, resulting in permanent deformation and image quality deterioration when ink solidifies during printing.
Innovation Solution
A method that involves jogging the web back and forth, repositioning it within a web deformation zone, or positioning an interval area in a deformation zone to prevent persistent deformation, ensuring the web remains ready for printing without delay when switching to the printing mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the web is maintained stationary by the transport pinch in ready-to-print mode, then the web is ready to be printed on without delay, but deformation of the web occurs in the form of pressure marks
Solution Approach 1:
The patent applies dynamic motion to the web during ready-to-print mode by continuously moving the web through the transport path at a reduced speed. This dynamic approach prevents the web from remaining stationary under pressure, thereby avoiding pressure marks and deformation while maintaining readiness for printing. The web is kept in constant gentle motion rather than static holding.
Solution Approach 2:
The transport pinch operates with periodic engagement and disengagement cycles during ready-to-print mode. The web is periodically advanced through the transport path and then held briefly, creating a rhythmic motion pattern. This periodic action prevents continuous pressure on the same web section, allowing recovery and preventing permanent deformation while maintaining printing readiness.
2Loss of time
If the web is maintained stationary in the heating zone during ready-to-print mode, then the printing system is ready for printing, but deformation of the web occurs due to heat-induced shrinkage
Solution Approach 1:
During ready-to-print mode, the web is continuously moved through the heating zone at a controlled reduced speed rather than remaining stationary. This dynamic movement prevents excessive heat concentration and water evaporation that cause shrinkage, while still maintaining the heating function. The web passes through the heating zone repeatedly at low speed, achieving thermal readiness without deformation.
Solution Approach 2:
The heating parameters are adjusted during ready-to-print mode to prevent deformation. The heating temperature is maintained at a level that prevents shrinkage while ensuring printing readiness. The web is heated at a controlled rate with continuous movement, changing the thermal parameters from high-temperature static heating to lower-temperature dynamic heating, thereby avoiding water evaporation and shrinkage.
3Measurement precision
If the web is kept stationary under transport pinch pressure, then the web position is controlled accurately, but pressure marks deform the web material
Solution Approach 1:
The transport pinch applies pressure periodically rather than continuously during ready-to-print mode. The pinch engages the web to advance it a short distance, then releases to allow the web to coast briefly, creating a rhythmic press-release cycle. This periodic pressure application maintains positional control accuracy while preventing continuous pressure marks and deformation of the web material.
Solution Approach 2:
The transport system transitions from static holding with continuous pressure to dynamic motion with intermittent pressure application. The web is continuously moved at reduced speed with the transport pinch providing periodic propulsion rather than continuous holding pressure. This dynamic approach maintains positioning accuracy while eliminating the harmful effects of sustained pressure on the web material.
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
Prevents persistent deformation of the web during the ready-to-print mode, allowing the web to recover before printing, thus maintaining image quality and ensuring quick resumption of printing without delays or image distortion.
Implementation Method 1
a deformation of the web may occur in the web in the heating zone, due to the heat applied by the pre-heat unit to the stationary web in the heat zone, such as deformation in the form of shrinkage of the web in a width direction due to evaporation of water from the web material
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B~3C
AI summary
A method is provided for controlling a web (3) in a printing apparatus (1). Said printing apparatus (1) comprises a transport assembly (61) for moving the web (3) through a transport path (MP) along a printing unit (10) for printing an image (PA) onto a print area of the web (3). The method comprises the steps of: Feeding the web (3) from a supply roll (R2) through the transport path (MP) to the transport assembly (61); Switching the printing apparatus (1) to a ready-to-print mode, wherein the printing unit (10) does not print an image (PA) on the web (3) and the web (3) is maintained ready to be printed on; wherein in a printing mode after the ready-to print mode the following steps are performed: Moving the web (3) through the transport path (MP) in a transport direction (C) along the printing unit (10) by the transport assembly (61); and printing the image (PA) onto the print area of the web (3) by the printing unit (10), wherein the image (PA) is printed by applying an image material, which solidifies on the web (3) during the printing step; and wherein the ready-to-print mode comprises the step of: operating the transport assembly (61) to prevent a deformation of the print area of the web (3) in the transport path (MP), while maintaining the web (3) in the ready-to-print mode. According to the invention the web (3) is maintained ready to print while preventing a deformation of the print area of the web (3) in the transport path (MP).