LED Drum Printer Ink Curing and Substrate Thermal Control
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Solution Overview
Problem
Roll-to-roll inkjet printers using UV light sources face challenges with heat buildup, which affects substrate accuracy and limits the types of substrates that can be used, especially for high-resolution and close-up printing applications like point of purchase items and packaging, where higher quality and varied substrate compatibility are required.
Innovation Solution
The implementation of LED curing systems in a drum-based printer structure with LED curing stations and pining stations, along with inert gas delivery, to maintain low temperatures and ensure accurate substrate motion and ink drop placement, allowing for a wide range of substrates to be printed without the need for platen chilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV light sources are used for curing ink, then curing effectiveness is improved, but substrate and mechanism heat buildup increases to 150-200 degrees F., causing placement accuracy issues and substrate deformation
Solution Approach 1:
The patent changes the fundamental parameter of the light source from UV lamps to LED arrays, operating at different wavelengths (385nm, 405nm, or 450nm). This parameter change enables effective curing of UV curable ink while maintaining operating temperatures below 100 degrees F., eliminating the heat buildup problem of traditional UV sources
Solution Approach 2:
The patent replaces the thermal-mechanical UV lamp system with an LED optical system. This substitution eliminates the need for complex cooling mechanisms like chilled platens and cooling water tubes, while achieving the same curing function with minimal heat generation
2Temperature
If chilled platens or cooling mechanisms are added to reduce heat, then substrate temperature control is improved, but device complexity and cost increase
Solution Approach 1:
The patent converts the inherent low-heat generation property of LEDs into a benefit, eliminating the need for active cooling systems. The design accepts and utilizes the natural thermal characteristics of LEDs to simplify the overall system, removing chilled platens, cooling water tubes, and associated complex temperature control mechanisms
3Productivity
If more print heads are added to increase throughput, then printing speed is improved, but printer cost and system complexity increase
Solution Approach 1:
The patent employs a dynamic scanning print head system that moves across the substrate in synchronization with substrate feed. This dynamic approach enables high-speed printing with fewer print heads, as the scanning mechanism effectively increases the printing coverage rate without proportionally increasing system complexity or cost
4Adaptability or versatility
If UV light sources are used, then a range of substrates can be printed, but thin and temperature-sensitive substrates stretch or wrinkle due to heat, reducing print quality
Solution Approach 1:
The patent changes the thermal parameter of the curing system by using LEDs instead of UV lamps. This enables printing on thin and temperature-sensitive substrates without the 150-200 degrees F. heat buildup that causes stretching and wrinkling, while maintaining effective ink curing
Solution Approach 2:
The patent converts the low thermal output of LEDs from a potential limitation into a benefit, enabling the printing of temperature-sensitive materials that would be damaged by traditional UV sources. This expands substrate compatibility while maintaining dimensional stability
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 solution provides high-quality, cost-effective printing across various formats and substrates, including super wide format and wide format outputs, with reduced heat-related issues and improved drop placement accuracy, enabling the production of high-resolution prints for close-up viewing.
Implementation Method 1
one or more LED light sources for curing the delivered ink
Implementation Method 2
LED curing systems in a drum-based printer structure with LED curing stations and pining stations, along with inert gas delivery, to maintain low temperatures
Data Source
AI summary
An enhanced printing system comprises a drum structure, a print carriage for delivering LED curable ink there from, such as from one or more print heads, and one or more LED light sources for curing the delivered ink. Some embodiments may preferably further comprise one or more LED pining stations, such as to control, slow or stop the spread of ink drops. As well, some printer embodiments may comprise a mechanism to deliver any of an inert gas, e.g. nitrogen, or other gas that is at least partially depleted of oxygen, between the LED energy source and the substrate. The disclosed LED printing structures typically provide higher quality and/or lower cost as compared to prior art systems, for a wide variety of printing matter output, such as for but not limited to super wide format (SWF) output, wide format (WF) output, packaging, labeling, or point of sale displays or signage.