Piezo Inkjet Pulse Waveform Control for Satellite Droplet Positioning
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Solution Overview
Problem
In liquid ejecting apparatuses like ink jet printers, satellite liquid droplets often land far from main liquid droplets due to differences in flying speed, leading to image quality deterioration, especially when ejecting liquids with higher viscosities.
Innovation Solution
A liquid ejecting apparatus with a voltage waveform ejection driving pulse that includes a first variation section, a hold section, and a second variation section with specific potential variations and hold times, where the second variation section has a steeper potential inclination and intermediate hold component, allowing the satellite liquid droplet to fly faster than the main droplet by rapidly extruding the meniscus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a liquid with high viscosity (8 mPa·s or more) is ejected using conventional ejection driving pulses, then the liquid can be ejected from the nozzles, but satellite liquid droplets are easily generated and land far from the main droplet, causing image quality deterioration
Solution Approach 1:
The ejection driving pulse is segmented into multiple distinct sections: a first contraction section to eject the main droplet, a hold section to maintain pressure, and a second contraction section with steeper inclination to eject the satellite droplet. This segmentation allows independent control of main droplet and satellite droplet ejection timing and speed, enabling the satellite droplet to be accelerated separately to reduce landing position difference.
Solution Approach 2:
The ejection driving pulse employs periodic pressure variations with specific timing: initial contraction for main droplet ejection, followed by a hold period, then a second contraction phase. This periodic action creates controlled oscillation in the liquid column, generating satellite droplets at predetermined intervals with enhanced flying speed through the second contraction section.
2Productivity
If the pressure chamber is contracted in one motion from maximum volume to minimum volume, then the main liquid droplet is ejected efficiently, but the satellite liquid droplet is ejected after a pause and does not follow the main droplet, causing landing position difference
Solution Approach 1:
The single contraction motion is divided into two distinct contraction sections: the first contraction section for main droplet ejection with moderate speed, and the second contraction section with steeper potential inclination for satellite droplet ejection. This segmentation eliminates the pause between droplet ejections while maintaining high ejection efficiency through optimized timing and pressure profiles.
Solution Approach 2:
The hold section is inserted between the two contraction sections to preliminarily prepare the liquid column state before the second contraction. This preliminary action maintains pressure and positions the liquid to ensure that when the second contraction occurs, the satellite droplet is immediately accelerated without pause, following the main droplet closely to the landing target.
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 that satellite liquid droplets are closer to main droplets on the landing target, improving image quality by minimizing the difference in landing positions and stabilizing the flying direction of satellite droplets.
Implementation Method 1
In a printer using a piezoelectric vibrator as a pressure generation unit, in general, ink is ejected from nozzles by first expanding a pressure chamber preliminarily (expansion step), holding the expansion state for a given time (hold step), and then rapidly contracting the pressure chamber (contraction step) to pressurize the ink in the pressure chamber.
Implementation Method 2
The ejection driving pulse is a voltage waveform including: a first variation section in which a potential is varied in a first direction to vary a volume of the pressure chamber; a hold section in which the volume of the pressure chamber varied in the first variation section holds for a given time; and a second variation section in which the potential is varied in a second direction opposite to the first direction to vary the volume of the pressure chamber.
Data Source
AI summary
The ejection driving pulse is a voltage waveform including: a first variation section; a hold section; and a second variation section. The second variation section includes: a first variation component in which the potential is varied in the second direction from the termination potential of the first variation section; an intermediate hold component in which the termination potential of the first variation component holds for a given time; and a second variation component in which the potential is varied in the second direction from the termination potential of the first variation component. The potential of the intermediate hold component is in the range from 50% to 60% of the potential of the hold section. A potential inclination of the second variation component is steeper than a potential inclination of the first variation component.