Helmholtz Resonance Bubble Removal in Inkjet Nozzles
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Solution Overview
Problem
Fluid ejecting apparatuses, such as inkjet printers, face challenges in completely removing micro-diameter bubbles from nozzles due to insufficient pressure, leading to poor ejection performance and potential clogging.
Innovation Solution
A fluid ejecting apparatus with a pressure chamber, pressure generating element, and control unit that generates a maintenance drive pulse with specific pulse portions to increase pressure and resonate with the natural vibration of the pressure chamber, effectively removing bubbles by maximizing pressure waves and resonance periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional maintenance process with pump and pressure generating elements is used, then thickened ink and large bubbles can be removed, but micro-diameter bubbles cannot be completely removed due to insufficient pressure
Solution Approach 1:
The patent applies Helmholtz resonance vibration to the fluid in the pressure chamber by controlling the pressure generating element to expand and contract at a frequency corresponding to the Helmholtz resonance period. This mechanical vibration creates strong pressure waves that effectively remove micro-diameter bubbles from the nozzles, overcoming the insufficient pressure of conventional maintenance methods.
Solution Approach 2:
The patent uses periodic pressure application synchronized with the Helmholtz resonance period of the fluid. The control unit generates drive pulses that cause the pressure generating element to expand and contract periodically, creating resonant pressure waves that amplify the pressure applied to the fluid and bubbles, enabling complete bubble removal.
2Reliability
If pressure is increased to remove bubbles, then bubble removal effectiveness improves, but fluid discharge stability may be compromised
Solution Approach 1:
The patent applies periodic pressure pulses synchronized with Helmholtz resonance rather than continuous high pressure. This periodic action removes bubbles effectively while allowing the fluid system to return to equilibrium between pulses, maintaining discharge stability. The pulse width is specifically controlled to be equal to or smaller than half the Helmholtz resonance period to optimize this balance.
3Reliability
If maintenance process is performed frequently, then nozzle performance is maintained, but productivity and printing efficiency decrease
Solution Approach 1:
The Helmholtz resonance-based maintenance method is highly effective at removing even micro-diameter bubbles, significantly improving nozzle recovery rates. This enhanced effectiveness reduces the frequency and duration of maintenance interruptions, thereby minimizing impact on printing productivity and overall efficiency.
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 solution reliably removes bubbles, improves nozzle recovery rates, and enhances the stability and efficiency of fluid discharge, reducing dot omission and ink clogging.
Implementation Method 1
a first pulse portion that drives the pressure generating element to cause the pressure chamber to expand into an expanded state and a second pulse portion that causes the pressure chamber to contract from the expanded state. The width of the second pulse portion is equal to or smaller than half the Helmholtz resonance period of the fluid with which the pressure chamber is filled.
Implementation Method 2
it is possible to further increase a force, owing to a pressure wave, that acts on fluid in the pressure chamber to further increase the speed at which a bubble disappears, while making it possible to discharge the bubble with the fluid.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A fluid ejecting apparatus that ejects fluid includes: a pressure chamber (13) that is filled with the fluid; a pressure generating element (17) that deforms a wall face of the pressure chamber to change a volume of the pressure chamber; a nozzle (15) that is in fluid communication with the pressure chamber and that is used for ejecting the fluid; and a control unit that generates a drive pulse for controlling the pressure generating element. The control unit is able to generate a maintenance drive pulse (300) for ejecting a bubble together with the fluid from the pressure chamber. The maintenance drive pulse includes a first pulse portion (Pwc) that drives the pressure generating element to cause the pressure chamber to expand into an expanded state and a second pulse portion (Pwd) that causes the pressure chamber to contract from the expanded state. The width of the second pulse portion is equal to or smaller than half the Helmholtz resonance period of the fluid with which the pressure chamber is filled.