UV Curing Control for Printing Head Nozzle Clogging
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Solution Overview
Problem
Printing apparatuses that discharge ultraviolet curable ink face challenges in ensuring sufficient curing without increasing ultraviolet ray irradiation, which can lead to nozzle clogging, and in maintaining throughput, as insufficient curing can result in image damage and ink contamination.
Innovation Solution
A printing apparatus with a control unit that manages the movement and irradiation of a printing head and ultraviolet irradiation unit in coordinated directions, allowing for separate controls of ink discharge and ultraviolet ray irradiation, including faster return speeds and adjusted irradiation intensities to ensure thorough curing while minimizing throughput reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of ultraviolet rays is increased to ensure sufficient curing of ultraviolet curable ink, then curing efficiency is improved, but the ultraviolet curable ink in the nozzle may be cured causing nozzle clogging
Solution Approach 1:
The ultraviolet irradiation process is segmented into two distinct phases: (1) during the forward movement, ultraviolet rays are irradiated onto the ultraviolet curable ink discharged onto the medium with a first irradiation amount; (2) during the return movement, ultraviolet rays are irradiated onto the printing head with a second irradiation amount that is different from the first. This segmentation allows different irradiation conditions to be applied to different targets at different times, preventing nozzle clogging while ensuring sufficient curing of the ink on the medium.
Solution Approach 2:
The system performs preliminary protection by irradiating ultraviolet rays onto the printing head during the return movement before the next ink discharge cycle begins. This preliminary action ensures that any residual ultraviolet curable ink in the nozzle is cured and removed, preventing clogging before it occurs, while the main curing action happens during the forward movement when ink is discharged onto the medium.
2Reliability
If the speed of reciprocating movement is reduced to irradiate ultraviolet rays for a longer period, then curing efficiency is improved, but throughput is significantly reduced
Solution Approach 1:
The system maintains continuous useful action by performing ultraviolet irradiation during both the forward movement (when ink is discharged onto the medium) and the return movement (when the printing head is repositioned). This eliminates idle time and ensures that the ultraviolet irradiation unit is continuously productive, improving curing efficiency without sacrificing throughput since the return movement time is utilized effectively.
Solution Approach 2:
The system dynamically adjusts the irradiation amount based on the movement phase: a first irradiation amount is applied during forward movement when ink is discharged onto the medium, and a second irradiation amount is applied during return movement when irradiating the printing head. This dynamic adjustment optimizes curing efficiency at different stages of the reciprocating cycle without requiring overall speed reduction.
3Reliability
If ultraviolet rays are irradiated during return movement to ensure curing, then curing efficiency is improved, but the same rays may reach the printing head causing ink curing in the nozzle
Solution Approach 1:
The system applies local quality by directing ultraviolet rays to different locations depending on the movement phase: during forward movement, rays are directed onto the medium where ink is discharged; during return movement, rays are directed onto the printing head. This localized application ensures that irradiation is concentrated where needed for curing while avoiding unnecessary exposure of the nozzle to high irradiation amounts that would cause clogging.
Solution Approach 2:
The system inverts the conventional approach by irradiating the printing head during the return movement instead of irradiating the medium during the return movement. This inversion allows the system to use the return movement time productively for curing residual ink in the nozzle while maintaining the forward movement as the primary ink discharge and curing phase, thereby preventing clogging without compromising throughput.
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 high curing efficiency (>97%) with reduced risk of image damage and nozzle clogging, while maintaining or improving throughput by optimizing the movement and irradiation strategies.
Implementation Method 1
an ultraviolet irradiation unit configured to reciprocate in the first direction along with the printing head, and configured to irradiate the ultraviolet curable ink discharged onto the medium with ultraviolet rays
Data Source
AI summary
A printing apparatus that performs a first control of performing discharge of ultraviolet curable ink from a printing head and irradiation of ultraviolet rays from an ultraviolet irradiation unit while performing a first movement along a main scanning direction and a second movement along a sub scanning direction from a print start position side to a print end position side, and a second control of performing irradiation of ultraviolet rays from the ultraviolet irradiation unit without performing discharge of ultraviolet curable ink from the printing head while performing the first movement and the second movement from the print end position side to the print start position side, and in which a movement speed of the first movement in the second control is faster than a movement speed of the first movement in the first control.