Liquid Ejection Head Refilling via Meniscus Positioning
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Solution Overview
Problem
Liquid ejection heads face challenges in refilling quickly with highly viscous liquids at high frequencies, leading to insufficient refilling and potential failure in ejecting droplets, especially when viscosity exceeds 40 cP at frequencies above 50 kHz.
Innovation Solution
The method involves a liquid ejection head design with a first flow path and a second flow path of larger cross-sectional area, where the piezoelectric element controls the capacity of the second flow path to facilitate efficient liquid refilling by positioning the meniscus within the second flow path, allowing for quick refilling and efficient droplet ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a highly viscous liquid is used to prevent recordable medium deformation, then the liquid can be ejected without causing curling or cockling, but the liquid flows slowly and the liquid ejection head cannot be sufficiently refilled at high frequencies
Solution Approach 1:
The liquid ejection head is divided into a common liquid chamber and multiple individual liquid chambers, each with its own refilling pathway. The communication portion with triangular prism members creates segmented flow channels that regulate liquid direction, allowing parallel refilling of multiple individual chambers from the common chamber, thereby increasing overall refilling speed while maintaining viscosity.
Solution Approach 2:
The communication portion features localized structural variations with triangular prism members that create different gap widths in different regions. The narrow gap on the individual liquid chamber side and wide gap on the common liquid chamber side create localized flow resistance differences, directing liquid flow preferentially from the common chamber to individual chambers, optimizing refilling efficiency for viscous liquids.
2Productivity
If the liquid ejection head is driven at high frequencies to meet commercial printing demands, then printing speed increases, but the liquid ejection head cannot be refilled sufficiently with highly viscous liquid
Solution Approach 1:
The liquid ejection head performs preliminary refilling action during the period when the piezoelectric element is returning to its initial state after droplet ejection. By positioning the meniscus in the individual liquid chamber before the next ejection cycle begins, the system ensures that liquid is already in position and ready for the next high-frequency ejection, maintaining reliability at high printing speeds.
Solution Approach 2:
The system dynamically adjusts the liquid meniscus position within the individual liquid chamber by controlling the timing of refilling relative to the piezoelectric element's operation cycle. The meniscus is positioned optimally in the chamber during idle periods and maintains readiness for rapid ejection during active periods, enabling the system to adapt to high-frequency operation requirements.
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 the liquid ejection head to be sufficiently refilled even at high frequencies, ensuring consistent droplet ejection by reducing flow resistance and leveraging surface tension for faster refilling of the second flow path.
Implementation Method 1
a piezoelectric element provided so as to correspond to the second flow path, the piezoelectric element allowing a droplet to be ejected from the orifice by changing the capacity of the second flow path with a voltage having a predetermined waveform being applied to the piezoelectric element
Implementation Method 2
leveraging surface tension for faster refilling of the second flow path
Data Source
AI summary
A method of driving a liquid ejection head includes preparing a liquid ejection head including first and second flow paths, and a piezoelectric element, a first step of applying a first voltage, which expands the second flow path, to the piezoelectric element while a meniscus of a liquid recessed from an orifice toward the second flow path is formed in a first flow path to move the meniscus to the second flow path, a second step of applying a second voltage, which contracts the second flow path, to the piezoelectric element while the meniscus that moves toward the first flow path is positioned in the second flow path to move the liquid to the first flow path, and a third step of applying a third voltage, which expands the second flow path, to the piezoelectric element to eject the liquid from the orifice after the liquid projects from the orifice.