Nozzle Taper and Ejection Pulse for High Viscosity Liquid
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Solution Overview
Problem
High viscosity liquids are challenging to eject efficiently due to inefficient pressure application within the pressure chamber, leading to unstable ejection and insufficient ejection amounts in existing liquid ejecting apparatuses.
Innovation Solution
A liquid ejecting apparatus with a nozzle having a taper portion and a straight portion, where the ejection side has a smaller opening area than the pressure chamber side, and an ejection pulse that includes a depressurizing portion to attract the meniscus to the taper portion and a pressurizing portion to eject the liquid before it returns to the straight portion, optimizing pressure application for efficient ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a nozzle with taper portion and straight portion is used to eject high viscosity liquid, then the liquid can be ejected, but the ejection becomes unstable and ejection amount is insufficient
Solution Approach 1:
The ejection pulse includes a depressurizing portion applied before the pressurizing portion to preliminarily attract the meniscus to the taper portion. This preliminary action positions the liquid interface optimally before the main ejection force is applied, ensuring stable and sufficient ejection of high viscosity liquid.
Solution Approach 2:
The ejection pulse is designed as a periodic waveform with distinct depressurizing and pressurizing portions. This periodic pressure variation creates a controlled cycle of liquid attraction and ejection, improving both ejection stability and amount for high viscosity liquids.
2Productivity
If pressure is applied to eject high viscosity liquid from the pressure chamber, then ejection occurs, but the pressure is not efficiently applied leading to unstable ejection
Solution Approach 1:
The nozzle structure features a taper portion with varying cross-sectional area, creating local quality variations in pressure distribution. The depressurizing portion of the ejection pulse further localizes pressure effects at the meniscus interface, ensuring efficient and stable pressure application for ejection.
Solution Approach 2:
The ejection pulse dynamically changes pressure parameters over time, transitioning from a depressurizing phase to a pressurizing phase. This parameter change optimizes the pressure application process, improving both ejection efficiency and stability for high viscosity liquids.
3Productivity
If the meniscus is allowed to return to the straight portion after being attracted to the taper portion, then the liquid can be replenished, but ejection timing is delayed
Solution Approach 1:
The depressurizing portion of the ejection pulse performs preliminary action by attracting the meniscus to the taper portion before the main pressurizing ejection phase. This preliminary positioning reduces the time required for liquid replenishment and optimizes ejection timing for high-frequency operation.
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 efficient ejection of high viscosity liquids by concentrating pressure on the taper portion, stabilizing droplet flight directions, and preventing excessive droplet elongation, while allowing for high-frequency ejection.
Implementation Method 1
an element that changes a pressure of liquid within the pressure chamber; and an ejection pulse generation section that generates an ejection pulse for operating the element... the ejection pulse has a depressurizing portion for depressurizing the liquid in order to attract a meniscus positioned on the second portion to the first portion, and a pressurizing portion for pressurizing the liquid in order to eject the liquid
Data Source
AI summary
A liquid ejecting apparatus includes: a pressure chamber that communicates with a liquid supply section and a nozzle; an element that changes a pressure of liquid within the pressure chamber; and an ejection pulse generation section that generates an ejection pulse for operating the element in order to eject the liquid from the nozzle. In the apparatus, the viscosity of the liquid is not less than 8 millipascal seconds. The nozzle has a first portion in which a liquid ejection side thereof has a smaller opening area than a pressure chamber side thereof, and a second portion which communicates with an ejection side end portion of the first portion. In addition, the ejection pulse has a depressurizing portion for depressurizing the liquid in order to attract a meniscus positioned on the second portion to the first portion, and a pressurizing portion for pressurizing the liquid in order to eject the liquid before the meniscus attracted to the first portion returns to the second portion.