Inkjet Printing Humidity Control for Drying and Cockling Suppression
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Solution Overview
Problem
Existing printing technologies face challenges in achieving robust drying performance, suppressing substrate deformation, and preventing jetting failure, particularly in double-sided printing machines, leading to issues like white spots, cockling, and streaks.
Innovation Solution
A printing apparatus with a print head that jets aqueous ink, a substrate moisture reduction unit to reduce moisture before image formation, and an absolute humidity adjustment unit to manage humidity around the nozzle surface, adjusting drying capacity and humidity levels based on substrate attributes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized drying device is installed to achieve robust drying performance, then drying capacity is improved, but device size and cost increase
Solution Approach 1:
The patent applies preliminary drying action by installing a drying device before the ink jet printing unit. This pre-dries the substrate to reduce its moisture content before printing, which improves overall drying performance after printing without requiring an oversized post-printing drying device. The preliminary drying unit reduces the moisture content of the substrate to 5% or less before the substrate enters the printing unit, thereby reducing the drying burden on the post-printing drying system.
2Stability of the object's composition
If the substrate is dried before image formation to suppress cockling, then substrate deformation is reduced, but nozzle surface dries causing jetting failure
Solution Approach 1:
The patent applies preliminary drying action by installing a drying device before the ink jet printing unit. This pre-dries the substrate to reduce its moisture content before printing, which improves overall drying performance after printing without requiring an oversized post-printing drying device. The preliminary drying unit reduces the moisture content of the substrate to 5% or less before the substrate enters the printing unit, thereby reducing the drying burden on the post-printing drying system.
Solution Approach 2:
The patent introduces a humidity control unit that serves as an intermediary between the drying device and the printing unit. This unit controls the humidity in the atmosphere surrounding the nozzle surface, preventing the nozzle from drying out while allowing the substrate to be pre-dried. The humidity control unit maintains the atmospheric humidity in a range that prevents nozzle ink thickening and jetting failure.
3Stability of the object's composition
If mechanical measures like tension application are used to suppress cockling, then substrate deformation is reduced, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical cockling suppression methods (such as tension application by roll-to-roll or paper stretching by suction) with a thermal field-based approach. By using a drying device to control the moisture content and temperature distribution across the substrate, the patent achieves cockling suppression without requiring complex mechanical tensioning systems or suction devices. This substitution of thermal processing for mechanical processing reduces device complexity.
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
Improves drying performance, suppresses substrate deformation, and prevents jetting failure, resulting in high-quality printed matter production.
Implementation Method 1
a heating device that heats the substrate before the image is formed
Implementation Method 2
a humidification source that humidifies the periphery of the nozzle surface
Data Source
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AI summary
Provided are a printing apparatus and a printing method that can realize improvement of drying properties, suppression of substrate deformation, and suppression of jetting failure. The printing apparatus includes a print head that jets an aqueous ink onto a substrate to form an image, a substrate moisture reduction unit that reduces moisture of the substrate before the image is formed by the print head, and an absolute humidity adjustment unit that adjusts an absolute humidity in a periphery of a nozzle surface of the print head.