Curved Surface Pad Printing via Inkjet Transfer
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Solution Overview
Problem
Conventional pad printing methods face challenges in producing high-quality images on curved surfaces due to the need for flat master plates, increased printing time, color registration errors, and transfer bleeds, especially when using ink-jet printers with larger gaps that reduce ink droplet placement accuracy.
Innovation Solution
The method involves keeping the transfer sheet in a flat state to maintain a uniform gap with the ink discharging means, using an elastic sheet to deform and tightly contact the medium, and employing ultraviolet-curing ink that is pre-thickened and finally cured, allowing for single-transfer operations and eliminating the need for master plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flat master plate is used in conventional pad printing, then the printing process can be performed, but it becomes difficult to provide quick and low-cost small runs of different types of curved-surface printing jobs
Solution Approach 1:
The invention extracts and eliminates the master plate from the printing system, replacing it with direct inkjet printing on the transfer pad. This removes the complex master plate production step while maintaining the ability to perform curved-surface printing, enabling quick and low-cost small runs of different jobs.
Solution Approach 2:
Instead of using a physical master plate that requires production and maintenance, the invention uses digital inkjet printing to create the printing pattern directly on the transfer pad. This digital copying approach eliminates master plate production complexity while maintaining design flexibility for different printing jobs.
2Manufacturing precision
If two transfer operations are performed in conventional pad printing, then the image can be transferred to the medium, but the printing time increases and color registration errors and transfer bleeds occur
Solution Approach 1:
The invention merges the ink application and transfer operations into a single step. By directly printing ink onto the transfer pad and then transferring it to the medium in one continuous operation, the system eliminates the need for separate ink application and transfer steps, reducing printing time and preventing color registration errors and transfer bleeds.
Solution Approach 2:
The invention performs preliminary inkjet printing directly on the transfer pad with the desired printing pattern before the transfer operation. This preliminary action creates a precise ink pattern that is then transferred in a single operation, eliminating the need for multiple transfer steps and associated timing and registration issues.
3Adaptability or versatility
If the transfer pad is formed with a three-dimensional structure to match curved surfaces, then curved-surface printing can be performed, but the gap between the ink-jet head and the transfer pad increases, reducing ink droplet placement accuracy
Solution Approach 1:
The invention uses a flexible transfer pad that can dynamically adapt its shape. The transfer pad is initially flat during the inkjet printing phase to maintain precise ink droplet placement, then deforms to match the curved surface during the transfer phase. This dynamic shape change allows the system to maintain printing precision while achieving adaptability to different surface shapes.
Solution Approach 2:
The invention changes the physical state and shape parameters of the transfer pad at different stages. During inkjet printing, the transfer pad maintains a flat state with controlled gap distance for accurate ink placement. During transfer, the pad deforms to conform to the curved surface. This parameter change allows the system to optimize for both precision and adaptability at different operational phases.
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 high-quality image formation on variously shaped media quickly and at low cost, reducing printing time, color registration errors, and transfer bleeds while allowing for efficient handling of small-run jobs.
Implementation Method 1
an elastic sheet is deformed to press the ink application surface against the medium so that the transfer sheet forms a tight contact with the surface of the medium
Implementation Method 2
the ink transferred to the medium is fused... ultraviolet-curing ink that is pre-thickened and finally cured
Data Source
Figure 1
Figure 2
Figure 3~3B
AI summary
The object of the present invention is to form, quickly and at low cost, a high-quality image on a medium formed with a curved surface. In order to achieve this object, the present invention is equipped with: an ink-jet head 2; a pre-curing ultraviolet irradiation device 3; a head unit 4 in which is installed the ink-jet head 2 and the pre-curing ultraviolet irradiation device 3; a medium holding unit 5 that holds a medium M; a transfer sheet unit holding unit 9 that holds a transfer sheet unit 8, in which a transfer sheet 6 is mounted to a transfer sheet holder 7; an elastic pad unit 10; a final curing ultraviolet irradiation device 11; a cleaning unit 12; and a control unit 13. The ink-jet head 2 applies ink to the transfer sheet 6 and the pad unit 10 pushes the transfer sheet 6 against the medium M, thus providing a pressure transfer of the ink applied to the transfer sheet 6 to the medium M.