Pneumatic Fluid Ejector for High-Viscosity Droplet Delivery
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Solution Overview
Problem
Existing fluid ejectors, such as ink-jet print-heads, are limited by pressure and actuation displacement, requiring careful gas removal and are intolerant to varying operating conditions, restricting the range of ejectable viscosities, volumes, and ejection rates.
Innovation Solution
A fluid ejector design using a body and gas supply means that creates a pressure difference by exposing nozzles to pressurized gas, allowing for relative movement to eject discrete volumes of fluids, independent of gas presence and tolerant to varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional ink-jet actuation means are used, then droplet ejection can be achieved, but the pressure and actuation displacement are severely limited, restricting the viscosities and volumes of ejectable fluids
Solution Approach 1:
The patent applies pneumatic pressure to the liquid ejectant within the ejection chamber to achieve droplet ejection. A gas supply means delivers pressurized gas to the first orifice, creating pressure that forces the liquid through the nozzle. This pneumatic approach overcomes the pressure limitations of piezoelectric and resistive heating actuators, enabling ejection of higher viscosity fluids and larger droplet volumes.
2Reliability
If conventional ink-jet dispensers are used, then droplet ejection is possible, but gas bubbles within the ink reduce pressure and displacement transients, requiring severe restrictions on gas volume and de-gassing processes
Solution Approach 1:
The nozzle is segmented into two separate orifices: a first orifice for gas supply and a second orifice for liquid ejection. This segmentation allows gas and liquid to be supplied independently, preventing gas bubbles from interfering with the liquid ejection process. The gas can be delivered through the first orifice to create pressure without forming disruptive bubbles in the liquid path.
3Productivity
If surface tension is used for nozzle refill, then replenishing of the nozzle can occur, but the refill force is small and must act against inertia and viscous drag, limiting continuous ejection rate
Solution Approach 1:
The patent uses pneumatic pressure delivered through the first orifice to refill the ejection chamber with liquid. This pressurized gas delivery system provides a stronger and more controllable refill force compared to relying solely on surface tension, enabling higher continuous ejection rates by rapidly replenishing the liquid supply against inertia and viscous drag forces.
4Manufacturing precision
If conventional print-head designs are used, then droplet ejection can occur, but the ejection chamber must be carefully filled without gas pockets, requiring precise manufacturing and de-gassing of ink
Solution Approach 1:
The system performs preliminary action by continuously supplying pressurized gas through the first orifice to maintain pressure in the ejection chamber. This continuous pressurization prevents gas pocket formation and ensures the liquid remains properly positioned for ejection, eliminating the need for precise one-time filling operations and de-gassing processes during manufacturing.
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
Enables ejection of a wider range of fluids with greater volumes and rates, eliminating the need for gas removal and improving operational flexibility.
Implementation Method 1
a pressure difference created thereby between the first orifice and the second orifice of the nozzle causes ejection of the ejectant from the nozzle through the second orifice
Data Source
AI summary
A fluid ejector for ejecting discrete volumes of ejectant includes a body with opposing first and second surfaces. One or more nozzles are defined as conduits extending through the body between the surfaces to connect first and second orifices at the first and second surfaces respectively. The fluid ejector further includes a gas supply means having a gas outlet and an ejectant supply means. The ejectant supply means supplies the ejectant to the nozzles at a pressure above ambient via their supply orifices. The supply orifice is defined in a conduit's side or is the second orifice. Relative movement of the gas supply means and body exposes first orifices to the gas outlet allowing the gas supply means to supply gas at a pressure above ambient, wherein a pressure difference thereby created between the first and second orifices causes ejection of the ejectant from the nozzles through the second orifices.