Ink Print Head Viscosity Control via Piezoelectric Pulse Sequences
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Solution Overview
Problem
The viscosity of ink in inkjet print heads can increase due to evaporation or solvent loss, leading to nozzle clogging and disruptions in print quality, such as streaks or missing image information, which existing technologies fail to address effectively during printing operations.
Innovation Solution
A method involving a piezoelement in the ink print head that applies adjustable sequences of pulses to detect and prevent increased viscosity by intermixing ink with fresh ink, using a 'pixel preview' to identify printing pauses and apply 'prefire' pulses to maintain or restore ink flow, thereby preventing nozzle failures and maintaining print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If printing operation continues without interruption, then productivity is improved, but ink viscosity increases due to evaporation causing nozzle clogging
Solution Approach 1:
The system performs preliminary detection of viscosity increase through activation current monitoring before actual nozzle clogging occurs. By detecting changes in the activation current of the piezoelement during printing pauses, the system can identify viscosity changes early and apply cleaning pulses to prevent complete nozzle blockage, thus maintaining both productivity and reliability
Solution Approach 2:
The system establishes a feedback loop by continuously monitoring the activation current of the piezoelement and comparing it against reference values. When deviations indicate viscosity increase, the system automatically responds by applying cleaning pulses or adjusting printing parameters, creating a closed-loop control system that maintains nozzle functionality while enabling continuous printing
2Reliability
If cleaning pulses are applied frequently, then nozzle reliability is improved, but printing productivity decreases due to interruptions
Solution Approach 1:
The system applies cleaning pulses preliminarily and selectively based on detected viscosity changes rather than applying them frequently or continuously. By monitoring activation current deviations and only initiating cleaning when necessary, the system maintains nozzle reliability while minimizing interruptions to printing productivity
Solution Approach 2:
The system implements periodic monitoring of activation current during printing pauses and applies cleaning pulses only when viscosity increase is detected. This periodic check-and-respond approach ensures nozzle functionality is maintained while avoiding unnecessary cleaning interruptions that would reduce printing productivity
3Reliability
If activation current is increased to maintain ink flow, then ink ejection reliability is improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts the activation current parameters of the piezoelement based on real-time viscosity detection. When viscosity increase is detected through activation current monitoring, the system modifies pulse characteristics (amplitude, duration, frequency) to maintain effective ink ejection while optimizing energy consumption, rather than continuously operating at maximum power
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 method effectively detects and mitigates increased viscosity in real-time, preventing nozzle failures and maintaining print quality by intermixing ink, reducing the need for complex inspections and minimizing disruptions in the printing process.
Implementation Method 1
A second sequence of pulses with adjustable parameters of this sequence is applied to the piezoelement in order to generate a vibration of the meniscus of the ink at the exit of the nozzle in order to intermix the ink having locally increased viscosity with ink having the initial viscosity
Implementation Method 2
The ink print head can include at least one nozzle configured to eject at least one ink droplet... a first sequence of pulses with adjustable parameters of this sequence is applied to a piezoelement of the ink print head
Data Source
AI summary
A method for reducing a locally increased viscosity of ink in an ink print head of an ink printer during printing operation includes: a determination of a printing pause with the aid of a pixel preview; an application of a first sequence of pulses for measurement of the activation current of a piezoelement of the ink print head; and an application of a second sequence of pulses for vibration of the ink meniscus at the exit of a nozzle if the ink print head to intermix the ink having locally increased viscosity with ink having the initial viscosity given a threatened failure of the nozzle.