Variable Radiation Dose Inkjet Printing for Surface Finish Control
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Solution Overview
Problem
In printing using curable inks, achieving uniform surface finishes, especially in images with varying ink densities and substrate colors, is challenging due to differential gloss levels and surface textures, particularly when trying to maintain a matte or glossy finish across the image.
Innovation Solution
A method involving multiple passes with varying radiation doses is employed using an inkjet printer, where different curing levels are achieved by adjusting the radiation power in each pass to control the surface finish, allowing for the creation of desired surface effects and textures by partially or fully curing the ink in specific areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If full power radiation is applied throughout the printing process, then a matt finish is achieved, but gloss areas cannot be created
Solution Approach 1:
The printing process is divided into multiple passes, with each pass applying a specific radiation dose to achieve different surface finishes. The first pass uses full power for matt finish, while subsequent passes use reduced power for gloss finish, allowing different regions of the substrate to have different surface characteristics.
Solution Approach 2:
The radiation source power is made variable and adjustable during the printing process. The system dynamically changes the radiation dose between passes, transitioning from high power (100%) in the first pass to lower power (e.g., 5-20%) in subsequent passes, enabling control over the curing degree and surface finish.
2Adaptability or versatility
If reduced power radiation is applied to create gloss finish, then surface gloss is improved, but matt areas cannot be achieved
Solution Approach 1:
The printing process is segmented into multiple passes with different radiation doses. The first pass applies full power radiation to create matt finish areas, while subsequent passes apply reduced power to create gloss finish areas, allowing both surface types to coexist in the same print.
Solution Approach 2:
The radiation dose is applied partially in subsequent passes rather than fully. By using reduced power (e.g., 5-20% of full power) in later passes, the ink is partially cured to create gloss finish, while the first pass with full power ensures complete curing for matt finish where needed.
3Manufacturing precision
If multiple passes with different radiation doses are used, then surface finish control is improved, but printing process complexity increases
Solution Approach 1:
The radiation source is designed with variable power capability, allowing dynamic adjustment between high and low power modes. This dynamic control enables the system to switch between different radiation doses within the same printing process without requiring multiple separate devices or complex mechanical changes.
Solution Approach 2:
The printing process maintains continuous operation across multiple passes without interrupting the workflow. The variable power radiation source allows seamless transition between different curing conditions, and the ink is progressively cured across passes, maintaining production efficiency while achieving surface finish control.
4Manufacturing precision
If additional ink is deposited in low-ink areas, then surface finish uniformity is improved, but ink usage increases
Solution Approach 1:
The radiation dose parameter is changed in subsequent passes to allow additional ink deposition in low-ink areas. By reducing the radiation power in later passes, the ink remains partially uncured and can be deposited in greater amounts without immediate solidification, enabling surface finish uniformity while managing ink usage through controlled curing.
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 approach enables efficient control of surface finishes, allowing for the creation of both glossy and matte regions within a single image, improving print resolution and reducing ink usage by allowing additional ink to be deposited in low-ink areas to match the substrate's finish, thereby minimizing gloss variations.
Implementation Method 1
Curable inks typically solidify by reaction, for example by polymerisation and/or crosslinking, on exposure to radiation.
Implementation Method 2
the emitted radiation applying a dose of radiation in a first range
Data Source
AI summary
The application describes a method and apparatus for controlling surface finish in the printing of a substrate in a plurality of passes using a curable print material and an ink jet printer having a radiation source. A first set of passes is carried out, including depositing ink on the substrate and emitting radiation from a radiation source toward the deposited ink. The emitted radiation applies a dose of radiation in a first range. A second set of passes is then carried out to deposit ink on the substrate. Further radiation is emitted from a radiation source toward the deposited ink, the emitted radiation applying a dose of radiation in a second range different from the first range.