Flat Heatable Body with Negative Pressure for Uniform Ink Drying
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Solution Overview
Problem
High-capacity inkjet printers face challenges in achieving uniform drying of web-shaped recording media due to non-constant thermal transfer and slip-stick effects caused by curved heating surfaces, which complicates adjustments for different paper types and print speeds.
Innovation Solution
A device with a flat heatable body and a negative pressure system that generates adjustable negative pressure to maintain consistent contact pressure, reducing friction and enabling uniform heat transfer, while allowing deactivation of negative pressure during pauses to prevent excessive drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a curved heating saddle is used to press the recording medium onto the sliding surface, then thermal contact is established, but the web tension increases and thermal transfer becomes non-uniform
Solution Approach 1:
The patent applies a curved heating saddle surface that is convexly curved in the transport direction. This curvature allows the recording medium to be pressed onto the heating surface while maintaining consistent contact pressure along the heating path, thereby achieving uniform thermal transfer without excessive web tension accumulation.
Solution Approach 2:
The patent replaces purely mechanical contact pressure (relying on web tension and gravity) with a negative pressure system. The negative pressure device creates a pressure differential that actively presses the recording medium onto the heating saddle, providing more precise and uniform control of contact pressure independent of web tension variations.
2Reliability
If a curved sliding surface is used for heating, then the recording medium is drawn onto the surface, but slip-stick effects occur due to non-uniform friction
Solution Approach 1:
The patent replaces mechanical friction-based contact with a negative pressure-based contact system. The negative pressure device creates a pressure differential that maintains consistent contact between the recording medium and heating saddle without relying on friction, thereby eliminating slip-stick effects while ensuring reliable contact.
Solution Approach 2:
The patent changes the contact mechanism from friction-dominated to pressure-differential-dominated. By controlling the negative pressure parameter, the system achieves uniform contact pressure along the curved heating path, eliminating the non-uniform friction that causes slip-stick effects.
3Manufacturing precision
If heat controllers are used to compensate for non-uniform thermal transfer, then thermal uniformity can be improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex thermal compensation control systems with a simpler negative pressure-based contact control system. By using negative pressure to ensure uniform contact pressure along the heating path, the system achieves uniform thermal transfer without requiring complex heat controllers or multi-zone temperature regulation.
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 solution ensures consistent and uniform drying of the recording medium, reduces friction forces by one-third compared to curved surfaces, and allows for adaptable heat transfer to various paper types and speeds, with reduced stress during printing pauses.
Implementation Method 1
a heatable body (20) whose contact surface (22) that faces towards the recording medium (10) is brought into contact with a side of said recording medium (10)
Implementation Method 2
A negative pressure device (30) generates a negative pressure at the contact surface (22) facing towards the recording medium (10)
Implementation Method 3
the water vapor that is released by the preheating is drawn off
Data Source
AI summary
In a method or device to dry a web-shaped recording medium in a printer, the web-shaped recording medium is printed with aqueous ink and subsequently directed with a predetermined web tension past a heatable body whose contact surface that faces towards the recording medium is brought into contact with a side of said recording medium that has not been freshly printed to dry said recording medium in a drying operation. A first guide element is arranged before the heatable body and a second guide element is arranged after the heatable body, the first and second guide elements guiding the recording medium. The contact surface of the heatable body is substantially flat. A negative pressure device generates a negative pressure at the contact surface facing towards the recording medium. The negative pressure is deactivated in a halt operation, the deactivation process taking place continuously over an adjustable time interval.