UV LED Illuminance Uniformity in Inkjet Curing
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Solution Overview
Problem
Conventional ultraviolet-curable inkjet systems face challenges in achieving uniform illuminance distribution when using UV LED elements, leading to uneven curing and image quality issues due to variations in ultraviolet irradiation across the nozzle row, particularly at the ends, and increased banding effects.
Innovation Solution
A liquid ejection device configuration where the ultraviolet generator includes multiple UV LED elements arranged to ensure higher illuminance at the ends than the center, with the light emitting range overlapping the nozzle row, and the lamp gap optimized between 10 to 30 mm, to uniformly cure ultraviolet-curable ink and prevent unnecessary irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If UV LED elements are arranged in a conventional uniform pattern, then the device complexity is reduced, but the illuminance distribution becomes non-uniform with lower illuminance at the ends
Solution Approach 1:
The patent applies local quality by differentiating the illuminance requirements of different regions. The control unit adjusts the driving current for UV LED elements at the end portions of the nozzle row differently from those at the central portion. Specifically, higher current is supplied to end UV LEDs to compensate for their naturally lower illuminance output, while central UV LEDs receive lower current. This creates a non-uniform current distribution that results in uniform overall illuminance across the nozzle row.
2Illumination intensity
If the ultraviolet generator is designed to irradiate a range larger than the nozzle row, then the illuminance distribution improves, but unnecessary ultraviolet irradiation occurs causing cumulative light quantity differences
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the driving current parameter for each UV LED element based on its position. The control unit modifies the electrical current supplied to each UV LED to compensate for positional variations in illuminance. This parameter adjustment ensures that each UV LED contributes appropriately to the overall uniform illuminance distribution, preventing both under-irradiation at ends and over-irradiation in the center, thereby eliminating unnecessary energy consumption and cumulative light quantity differences.
3Illumination intensity
If optical design with multiple lenses is used to achieve uniform illuminance, then the illuminance distribution improves, but the size and cost of the ultraviolet generator increase
Solution Approach 1:
The patent replaces the mechanical/optical system (multiple lenses and complex optical design) with an electrical control system. Instead of using physical optical components to redistribute light, the invention uses a control unit that electronically adjusts the driving current to each UV LED element. This substitution of electrical control for mechanical/optical design achieves uniform illuminance distribution while maintaining a compact and cost-effective ultraviolet generator structure.
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 configuration ensures uniform curing of ultraviolet-curable ink, reducing end-of-generator illuminance decreases and preventing banding, thereby improving image quality and shaping accuracy in inkjet printing and 3D object formation.
Implementation Method 1
the ultraviolet generator includes a plurality of UV LED elements which are LED elements for generating ultraviolet
Implementation Method 2
an ultraviolet-curable ink, which is a liquid that cures according to ultraviolet
Data Source
AI summary
A liquid ejection device that ejects an ultraviolet-curable liquid includes an inkjet head, which is an ejection head that ejects the ultraviolet-curable liquid; a scanning driver that causes the inkjet head to perform a main scan; an ultraviolet generator; and a light source driver; where the ultraviolet generator irradiates the ultraviolet while moving in the main scanning direction together with the inkjet head; the ultraviolet generator includes a plurality of UV LED elements; the plurality of UV LED elements are arranged such that a light emitting range overlaps a range of the nozzle row in a sub scanning direction; and the light source driver drives the plurality of UV LED elements such that an illuminance at an end portion in the sub scanning direction is larger than an illuminance at a central portion in the light emitting range.