Inkjet Printhead Humidity Control for Drying and Cockling
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Solution Overview
Problem
Existing printing technologies face challenges in achieving robust drying performance, substrate deformation, and jetting failure, particularly in double-sided printing machines, leading to issues like white spots, cockling, and streaks on printed matter.
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 the nozzle surface environment, optimizing drying conditions and humidity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized drying device is installed after ink jetting to achieve robust drying performance, then drying capability 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 jetting unit. This pre-dries the substrate to reduce its moisture content before ink application, thereby improving overall drying performance without requiring an oversized post-jetting drying device. The preliminary drying unit reduces substrate moisture conservatively to ensure sufficient drying capacity while maintaining compact device dimensions.
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 local quality by creating different humidity conditions in different locations. The drying device is positioned to dry only the substrate surface in the drying path while the nozzle surface remains in a humid environment. This localized drying approach suppresses cockling in the substrate without causing nozzle surface drying that would lead to jetting failure.
Solution Approach 2:
The patent introduces a humidifying unit as an intermediary between the drying device and the ink jetting unit. This humidifying unit restores humidity to the atmosphere around the nozzle, preventing nozzle surface drying and maintaining jetting performance, while the substrate continues to be dried by the drying device to suppress cockling.
3Stability of the object's composition
If a cockling suppression unit is added during drying to suppress substrate deformation, then substrate shape stability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the cockling suppression function from a separate mechanical suppression unit and integrates it into the existing drying device through controlled humidity management. By using the drying device's heat and airflow to create optimal drying conditions that prevent cockling, rather than adding separate tension application or suction mechanisms, the solution reduces substrate deformation without increasing 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 substrate moisture reduction unit to reduce moisture in a substrate before an image is formed
Implementation Method 2
a print head that jets an aqueous ink onto a substrate to form an image
Implementation Method 3
an absolute humidity adjustment unit to adjust an absolute humidity in a periphery of a nozzle surface of the print head
Data Source
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.