Piezoelectric Inkjet Nozzle Waveform Control for Viscosity Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid ejecting apparatuses face challenges in uniformizing ejection properties between nozzles due to temperature differences and viscosity variations, particularly with photocurable liquids like UV ink, which are exacerbated by non-linear piezoelectric element displacement properties.
Innovation Solution
A liquid ejecting apparatus that generates a first driving waveform for ejection and a second driving waveform for maintenance, with the second waveform featuring a contraction element and expansion element to drive the piezoelectric element in a region of large displacement, reducing temperature differences and viscosity variations between nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minute vibration driving pulse with small voltage change is applied to the piezoelectric element, then liquid is not caused to be ejected and thickening of the meniscus is reduced, but the piezoelectric element is heated and liquid in the pressurizing chamber is heated, causing agitation and viscosity changes
Solution Approach 1:
The patent applies parameter changes by modifying the voltage waveform parameters of the minute vibration driving pulse. Specifically, it uses a trapezoidal waveform with a plateau portion at a potential lower than the reference potential, which changes the voltage change amount and timing characteristics. This parameter modification allows the piezoelectric element to generate sufficient heating effect while controlling the ejection behavior, thereby addressing the contradiction between ejection property uniformity and liquid temperature control.
2Manufacturing precision
If the reference potential of the trapezoidal wave is set to a high potential in the non-linear region, then displacement amount of the piezoelectric element is made large for high viscosity liquid ejection, but temperature difference between nozzles increases and ejection property variation occurs
Solution Approach 1:
The patent applies local quality by differentiating the driving waveform parameters for different nozzle types. It sets the reference potential and expansion potential specifically for maintenance nozzles (which do not eject liquid during normal operation) to be different from those of ejection nozzles. This localized parameter adjustment ensures that maintenance nozzles receive appropriate heating to prevent thickening without causing excessive temperature differences that would lead to ejection property variations across different nozzle types.
3Reliability
If maintenance operation is performed to prevent thickening of liquid in nozzles, then ejection property uniformity is improved, but maintenance operation time increases
Solution Approach 1:
The patent applies periodic action by implementing maintenance operation at specific intervals during the printing process. Instead of continuous maintenance, it performs maintenance operations periodically based on the printing status, such as after a certain number of ejection cycles or when detecting nozzle clogging conditions. This periodic approach maintains ejection property uniformity while minimizing the total maintenance operation time compared to continuous maintenance strategies.
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 approach reduces ejection property variations and shortens maintenance operation time by effectively heating the liquid in the pressurizing chamber, suppressing thickening and crosstalk, and maintaining uniform ejection performance across all nozzles.
Implementation Method 1
as the pressure generator, a piezoelectric element which is deformed when a driving signal (driving voltage) is supplied is preferably used
Implementation Method 2
When such a minute vibration driving pulse is applied to a piezoelectric element, the piezoelectric element is heated, liquid in the pressurizing chamber is heated
Data Source
AI summary
It is possible to generate an ejection driving pulse which ejects ink, and a plurality of minute vibration driving pulses which cause a pressure fluctuation in ink in a pressurizing chamber to an extent of not causing the ink to be ejected; the ejection driving pulse includes a first expansion element which causes the pressurizing chamber to be expanded by being changed from a reference potential to a first potential which is lower than the reference potential, and a first contraction element which causes the pressurizing chamber to be contracted by being changed from the first potential to the reference potential; and the minute vibration driving pulse includes a second contraction element which causes the pressurizing chamber to be contracted by being changed from a second potential which is lower than the reference potential to a third potential which is higher than the second potential and the first potential, and is lower than the reference potential, and a second expansion element which causes the pressurizing chamber to be expanded by being changed from the third potential to the second potential.