Piezo Inkjet Nozzle Aging via Non-Ejection Waveforms
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Solution Overview
Problem
The ejection characteristics of liquid ejecting apparatuses, such as ink jet printers, deteriorate over time due to repeated driving of pressure generation units like piezoelectric vibrators, leading to uneven ink distribution and potential streaks in recorded images, as the polarization characteristics change and the pressure generation units become polarized differently than the applied electric field.
Innovation Solution
A liquid ejecting apparatus that includes a control unit to drive pressure generation units using a non-ejection driving waveform, which is adjusted based on the cumulative number of times the driving waveform is applied, to perform an aging process that matches the characteristics of pressure generation units, reducing variations and maintaining ejection quality without unnecessary ink consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driving voltage is increased to compensate for deteriorating ejection characteristics, then the ejection performance is temporarily improved, but the pressure generation unit deteriorates faster and characteristic variation worsens
Solution Approach 1:
The patent applies preliminary action by performing an aging process on the pressure generation unit before actual ejection operations. This involves applying a predetermined number of driving waveforms to pre-deteriorate the piezoelectric vibrator, allowing it to reach a stable polarization state. By doing this in advance, the unit undergoes characteristic changes during the aging process rather than during normal operation, thereby extending its service life while maintaining reliable ejection characteristics.
2Manufacturing precision
If correction driving waveforms are applied to match characteristics of pressure generation units, then ejection uniformity is improved, but additional processing time is required
Solution Approach 1:
The patent performs the characteristic matching action in advance during the aging process. By applying driving waveforms to uniformize the characteristics of multiple pressure generation units before they are put into service, the system achieves ejection uniformity without requiring additional correction time during actual operation. The aging process consolidates what would otherwise be ongoing adjustment work into a preliminary setup phase.
3Manufacturing precision
If the aging process is performed using ejection driving waveforms, then characteristic uniformity is achieved, but unnecessary ink consumption occurs
Solution Approach 1:
The patent extracts the essential function of the driving waveform (applying electrical signals to the piezoelectric vibrator) while removing the ejection function (liquid discharge). By using driving waveforms that cause the piezoelectric element to expand and contract without generating sufficient pressure for liquid ejection, the system achieves characteristic uniformity during aging without consuming ink. This separates the characteristic-forming function from the liquid-ejection function.
4Reliability
If correction is applied to frequently used nozzles to maintain their performance, then their ejection characteristics are improved, but the variation between nozzles increases
Solution Approach 1:
The patent applies preliminary uniformizing action to all pressure generation units during the aging process, before differential deterioration occurs during normal use. By subjecting all units to the same predetermined number of driving waveforms in advance, the system establishes a baseline uniformity. This prevents the need for later differential correction that would create inconsistency among nozzles.
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 solution ensures that the ejection characteristics of nozzles are unified, reducing variations and preventing unevenness or streaks in recorded images, while minimizing ink consumption and maintaining throughput by performing the aging process outside the recording region.
Implementation Method 1
a piezoelectric vibrator 20 that changes in thickness when a driving waveform is applied
Implementation Method 2
the liquid meniscus vibrates minutely when a non-ejection driving waveform is applied, so that the liquid does not reach the nozzle
Data Source
AI summary
A CPU serving as a counting unit counts the cumulative number of times a driving pulse is applied to a piezoelectric vibrator. A driving signal generation unit is able to generate an aging driving pulse set by a driving parameter to the extent that ink is not ejected from a nozzle and performs an aging process of driving the piezoelectric vibrator using the aging driving pulse set by a driving parameter in accordance with a cumulative number of applications in a region outside an ejection region on a recording medium.