UV Curing Printer Printhead Zones Ink Flow Control
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Solution Overview
Problem
Producing high-quality images on non-porous substrates with aqueous inks is challenging due to ink flow issues, as different images require varying ink flow and drying times, and UV inks can solidify too quickly, leading to defects.
Innovation Solution
A printer system that provides varying degrees of UV radiation exposure at different times during image printing, using multiple printheads and UV radiation sources to control ink flow and curing, ensuring sharpness of fine features and uniformity of solid areas with accurate color formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If UV radiation is applied immediately after ink ejection, then ink solidification speed is improved, but ink spread is insufficient leading to image defects
Solution Approach 1:
The printing system is divided into multiple print zones with separate printheads and UV radiation sources. Each zone can independently control UV exposure timing and intensity, allowing different portions of the substrate to receive different degrees of curing based on their specific requirements.
Solution Approach 2:
The system dynamically adjusts UV radiation exposure by varying the distance between UV sources and printheads, and by controlling the timing of UV activation. This dynamic control allows optimization of ink spread versus solidification for different image regions.
2Productivity
If UV radiation sources are positioned close to printheads, then ink curing efficiency is improved, but ink spread is restricted
Solution Approach 1:
The system introduces a temporal dimension to the UV curing process by delaying UV activation until after ink ejection and allowing controlled spread. Multiple zones operate at different times and positions, transforming a spatial proximity problem into a temporal sequencing solution.
3Adaptability or versatility
If aqueous ink is used on non-porous substrates, then substrate compatibility is improved, but ink anchoring is insufficient causing flow issues
Solution Approach 1:
The system performs preliminary UV curing of the ink shortly after ejection in the first print zone, creating an anchored base layer before the substrate reaches subsequent zones. This preliminary action secures the ink to non-porous substrates before further processing.
Solution Approach 2:
The ink undergoes phase transition from liquid to solid through UV-induced polymerization. This phase change provides anchoring to the substrate and prevents uncontrolled flow, solving the adhesion problem on non-porous surfaces.
4Manufacturing precision
If different ink flow rates are used for different image regions, then image quality is improved, but system complexity increases
Solution Approach 1:
The printing system is segmented into multiple independent print zones, each capable of different UV exposure settings. This physical segmentation allows different ink flow and curing parameters for different image regions without requiring complex real-time adjustment mechanisms.
Solution Approach 2:
The system changes physical parameters (UV radiation distance, UV activation timing, printhead positioning) to control ink behavior in different zones. These parameter changes enable region-specific ink flow control while maintaining relatively simple hardware architecture.
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 system effectively improves image quality by allowing precise control over ink flow and curing, preventing defects and ensuring uniformity and accuracy in both fine features and solid areas.
Implementation Method 1
UV inks have been developed that have the unique advantage of including photo-sensitive materials so the inks can be cured with UV radiation and stabilized on the substrates
Data Source
AI summary
A printer includes a first printhead operatively connected to a source of ultraviolet (UV) curable ink having a first color, a first source of UV radiation following the first printhead in the process direction by a first predetermined distance, a second printhead operatively connected to the source of UV curable ink having the first color, and a second source of UV radiation following the second printhead in the process direction by a second predetermined distance that is greater than the firsts predetermined distance. The first predetermined distance enables the first source of UV radiation to fix the UV curable ink ejected by the first printhead before passing the second printhead and the second predetermined distance enables the ink ejected by the second printhead to flow over a portion of the substrate before the second source of UV radiation fixes the UV curable ink ejected by the second printhead.