Preheater Temperature Control for Web Deformation in Printing Systems
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Solution Overview
Problem
In web printing systems, temporary printing stops lead to thermal contraction and deformation of the web, resulting in insufficient preheating and local fixing defects when printing resumes, due to the web's reduced adhesion with the preheater and inadequate heat transfer, especially when using suction mechanisms that disturb paper travel and image quality.
Innovation Solution
A temperature control unit in the second printing apparatus preheats the web from the opposite surface to a target temperature before restarting print operations and decreases the temperature once the deformed portion passes through, ensuring sufficient heat is applied to the toner image and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the web is continuously heated by the preheater and heating roll during a temporary printing stop, then the web temperature is maintained, but the web moisture evaporates and causes thermal contraction and deformation
Solution Approach 1:
The patent applies preliminary action by detecting the temporary printing stop state before thermal contraction occurs and proactively controlling the preheater temperature. When a printing stop is detected, the preheater temperature is reduced to prevent excessive heating that would cause web deformation, while still maintaining sufficient temperature for subsequent printing operations.
2Temperature
If the suction force of the suction mechanism is increased to improve web adhesion to the preheater, then web preheating efficiency is improved, but paper travel and web behavior are disturbed affecting image quality
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the suction force parameter based on the printing state. During temporary printing stops, the suction force is reduced or turned off to prevent web deformation. During active printing, the suction force is optimized to ensure proper web adhesion and preheating while maintaining stable web travel and image quality.
3Temperature
If the preheater temperature is maintained at target temperature continuously, then preheating performance is optimized, but power consumption increases unnecessarily during temporary stops
Solution Approach 1:
The patent applies dynamics by making the preheater temperature control dynamic rather than static. The system continuously monitors the printing state and adjusts the preheater temperature accordingly - maintaining target temperature during active printing for optimal performance, and reducing temperature during temporary stops to minimize power consumption while preventing web deformation.
4Productivity
If printing restarts after a temporary stop, then productivity is restored, but the thermally contracted deformed portion causes insufficient preheating and local fixing defects
Solution Approach 1:
The patent applies feedback by using the printing state detection as feedback input to control the preheater temperature. When printing restarts after a temporary stop, the system detects the resumption of printing and automatically adjusts the preheater temperature to ensure the deformed web portion receives adequate preheating, preventing fixing defects and ensuring reliable print quality.
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 prevents fixing defects by ensuring proper preheating of thermally contracted and deformed web portions, maintaining image quality, and reducing unnecessary power consumption by optimizing temperature control during print restarts.
Implementation Method 1
a second preheating unit provided in the second printing apparatus, and configured to preheat a recording medium from a first surface of the recording medium that is an opposite side of a second surface of the recording medium
Implementation Method 2
Each of the printing apparatuses is an electrophotographic printing apparatus that heats, melts, and fixes a transferred toner image, and has a photosensitive drum, a developing device, and a heat fixing device
Implementation Method 3
heats, melts, and fixes a transferred toner image
Implementation Method 4
the web that is stopped in the heat fixing device of the first printing apparatus is continuously heated by the preheater and the heating roll, the moisture of the web is evaporated as time passes, and a portion of the web is greatly thermally contracted and deformed
Implementation Method 5
each of the first printing apparatus and the second printing apparatus has a preheater to fix an image to the web W and a mechanism (hereinafter, referred to as 'suction mechanism') to suck the web to the preheater
Data Source
AI summary
A printing system includes a first printing apparatus, a second printing apparatus, and a control device. The second printing apparatus is provided at a rear stage of the first printing apparatus, and includes a second preheating unit that preheats a recording medium from one surface before thermally fixing a toner image to another surface, and a temperature control unit that increase the temperature of the second preheating unit from a normal temperature to a target temperature, in response to a printing preparation instruction received in a temporary printing stop state from the control device. The control device starts printing, when the temperature of the second preheating unit reaches the target temperature. The temperature control unit decreases the temperature of the second preheating unit from the target temperature to the normal temperature, when the recording medium is conveyed by a length from a deformed portion to the second preheating unit.