Liquid Ejecting Apparatus Pseudo Nozzle High Viscosity Stability
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Solution Overview
Problem
Existing liquid ejecting technologies face stability issues when ejecting liquids with high viscosity due to increased resistance at the nozzle wall, leading to energy loss and poor ejection stability.
Innovation Solution
A liquid ejecting apparatus that forms a pseudo nozzle using a liquid membrane within the nozzle, reducing resistance and energy loss by controlling the meniscus shape through a piezoelectric element and displacement amplifying mechanism, allowing for stable ejection of high viscosity liquids with smaller diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the viscosity of the liquid is increased, then the liquid can carry larger particle diameters, but the resistance at the boundary between the inner wall surface of the nozzle and the liquid increases and energy loss increases leading to poor ejection stability
Solution Approach 1:
The inner wall surface of the nozzle is given a specific roughness (Ra 0.01 μm to 1 μm) in the liquid ejection direction to reduce resistance. This local modification of surface quality allows high viscosity liquids with large particles to be ejected stably by reducing boundary resistance without requiring overall nozzle redesign.
Solution Approach 2:
The nozzle inner wall surface roughness is controlled within a specific range (Ra 0.01 μm to 1 μm) to optimize the balance between reducing resistance for high viscosity liquids and maintaining ejection stability. This parameter optimization enables the nozzle to handle liquids with higher viscosity and larger particles effectively.
2Quantity of substance
If the viscosity of the liquid is increased, then the liquid can carry larger particle diameters, but the energy loss of the liquid required for ejection due to friction increases
Solution Approach 1:
The inner wall surface is modified with controlled roughness (Ra 0.01 μm to 1 μm) to reduce frictional resistance locally at the liquid-wall boundary. This reduces the energy loss required for ejection while maintaining the capability to transport liquids with larger particle diameters.
3Loss of energy
If the liquid membrane thickness is increased to form a pseudo nozzle, then the resistance is reduced, but the diameter of the liquid to be ejected increases
Solution Approach 1:
The liquid membrane thickness is controlled within a specific range (0.1 μm to 10 μm) to optimize the balance between reducing resistance through pseudo-nozzle formation and maintaining a small ejected liquid diameter. This parameter control allows the system to achieve low resistance without excessive increase in droplet size.
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 apparatus achieves stable ejection of high viscosity liquids with reduced energy loss and increased flying speed, while preventing nozzle clogging and suppressing cavitation, enabling efficient ejection of liquids with large particle diameters.
Implementation Method 1
a piezoelectric element and a displacement amplifying mechanism, wherein the piezoelectric element changes shape in response to applied voltage and the displacement amplifying mechanism amplifies a displacement of the piezoelectric element
Implementation Method 2
When a meniscus of liquid to be ejected is pulled into a straight portion of the nozzle, a liquid membrane is formed at an inner wall surface of the nozzle
Data Source
Figure 1
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AI summary
A liquid ejecting apparatus includes a nozzle that ejects liquid with a viscosity of 50 mPa·s or higher; a pressure chamber communicating with the nozzle; a pressure change portion that changes a pressure of the liquid in the pressure chamber; and a controller that controls the pressure change portion. The controller, by driving the pressure change portion, executes first control of pulling a center portion of a meniscus of the liquid in the nozzle toward the pressure chamber, and forming a liquid membrane with the liquid at an inner wall surface of the nozzle by the pressure change portion decreasing the pressure of the liquid in the pressure chamber; and second control of, in a state in which the liquid membrane is formed at the inner wall surface of the nozzle, inverting a shape of the center portion of the meniscus to a protruding shape protruding toward an opening of the nozzle on a side opposite to the pressure chamber and forming a liquid column, and further, ejecting the liquid column from the center portion of the meniscus having the protruding shape toward the opening of the nozzle so as not to contact the liquid membrane by the pressure change portion increasing the pressure of the liquid in the pressure chamber.