UV Inkjet Nozzle Spacing for Curing Control
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Solution Overview
Problem
Inkjet printers using UV-curable ink face ejection defects due to UV ink curing on the ejection surface, leading to nozzle clogging, as UV light from the irradiator causes premature curing, making it difficult to remove the cured ink effectively.
Innovation Solution
A printing apparatus with a dual nozzle configuration, where one nozzle row ejects a photopolymerization initiator and the other ejects a polymerizable compound with color material, positioned such that the polymerizable compound is closer to the irradiation unit, reducing curing issues by controlling the distance between the irradiation unit and each nozzle row.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the irradiator is positioned close to the ejection head to improve curing efficiency, then the curing speed increases, but UV ink cures on the ejection surface causing nozzle clogging
Solution Approach 1:
The ink is divided into two separate liquids: one containing the photopolymerization initiator and the other containing the polymerizable compound and color material. These two liquids are ejected from different nozzle rows, allowing independent control of their positions relative to the irradiator. This segmentation enables the initiator to be positioned farther from the irradiator while the polymerizable compound remains closer, resolving the contradiction between curing efficiency and nozzle clogging.
Solution Approach 2:
Different parts of the ejection head are assigned different functions: the first nozzle row (ejecting initiator) is positioned farther from the irradiator to prevent premature curing, while the second nozzle row (ejecting polymerizable compound) is positioned closer to enable efficient curing. This local differentiation of spatial positioning optimizes both curing efficiency and prevents nozzle clogging in their respective zones.
2Loss of time
If UV ink is ejected close to the irradiator to reduce drying time, then the curing efficiency improves, but the UV ink cures excessively on the ejection surface making maintenance difficult
Solution Approach 1:
By separating the photopolymerization initiator and polymerizable compound into different nozzle rows with different distances from the irradiator, the system achieves optimal curing speed while preventing excessive curing on the ejection surface. The initiator is positioned farther away to avoid premature curing that would complicate maintenance, while still enabling efficient curing on the recording medium.
3Device complexity
If a single nozzle row ejects both initiator and polymerizable compound, then the device structure is simpler, but UV light causes premature curing on the ejection surface
Solution Approach 1:
The single nozzle row is divided into two separate nozzle rows: one for ejecting the photopolymerization initiator and another for ejecting the polymerizable compound and color material. This segmentation allows different spatial positioning relative to the irradiator, preventing premature curing while maintaining reasonable device complexity through a systematic dual-nozzle configuration.
Solution Approach 2:
The solution moves from a single-dimensional (one nozzle row) to a two-dimensional arrangement (two nozzle rows at different distances from the irradiator). This dimensional change enables independent optimization of positioning for each liquid type, preventing premature curing while maintaining efficient curing on the recording medium.
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 configuration minimizes ejection defects by suppressing curing near the nozzles, reducing maintenance costs and improving print efficiency by allowing more UV irradiation onto the recording medium.
Implementation Method 1
a first liquid containing a photopolymerization initiator that initiates a polymerization reaction of a polymerizable compound by irradiation with light
Data Source
AI summary
A printing apparatus includes an ejection head including a first nozzle row configured to eject, toward a recording medium, a first liquid containing a photopolymerization initiator and a second nozzle row configured to eject, toward the recording medium, a second liquid containing the polymerizable compound and a color material and not containing the photopolymerization initiator, a driving unit configured to change relative positions of the ejection head and the recording medium, and an irradiation unit configured to irradiate, with the light, the recording medium onto which the first liquid and the second liquid are deposited. The first liquid and the second liquid are ejected from the ejection head so that the second liquid overlaps the first liquid on a surface of the recording medium. A distance between the irradiation unit and the first nozzle row is longer than a distance between the irradiation unit and the second nozzle row.