Print Head Vibration During Deceleration Ramps
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Solution Overview
Problem
Ink printing apparatuses face issues with ink drying out in nozzles during print interruptions, leading to viscosity changes and disrupted ink ejection during deceleration and acceleration ramps, which can cause printing failures.
Innovation Solution
A method that generates print clock pulses to control the print controller, triggering vibration pulses at the print heads during deceleration and acceleration ramps to maintain ink flow and prevent viscosity changes, ensuring continuous printing by stirring the ink with vibration cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If printing is continued during deceleration and acceleration ramps, then productivity is maintained, but ink drying out in nozzles occurs due to increased time intervals between print dock pulses
Solution Approach 1:
The patent applies mechanical vibration by sending vibration pulses to the print head during deceleration and acceleration ramps. These vibration pulses cause the ink in the nozzles to vibrate, preventing it from drying out and maintaining reliable ink ejection during the ramps, thus resolving the contradiction between maintaining productivity and ensuring ink ejection reliability
Solution Approach 2:
The patent implements preliminary action by sending vibration pulses before the next print dock pulse occurs during the ramps. This preliminary vibration of the ink in the nozzles prevents drying out in advance, ensuring that when the next print dock pulse arrives, the ink is still in a suitable state for ejection, thereby maintaining both productivity and reliability
2Loss of time
If the feed speed is reduced to a complete stop during print interruption, then monitoring time is available, but ink drying out occurs more rapidly due to longer time intervals between print dock pulses
Solution Approach 1:
The patent uses mechanical vibration to send vibration pulses to the print head during the complete stop period. This vibration prevents ink from drying out in the nozzles during the monitoring interruption, allowing the system to maintain nozzle functionality while still providing necessary monitoring time
3Reliability
If flushing medium is flushed through all nozzles regularly, then ink drying out is prevented, but device complexity and operational interruptions increase
Solution Approach 1:
The patent extracts the essential function of preventing ink drying out (which was previously achieved through complex flushing systems) and implements it through a simpler vibration-based approach. The vibration pulses directly agitate the ink in the nozzles without requiring external flushing media or complex flushing mechanisms, thus reducing device complexity while maintaining reliability
Solution Approach 2:
The patent replaces the mechanical flushing system with a vibration-based solution. Instead of using physical flushing media to prevent ink drying out, the system uses vibration pulses to agitate the ink in the nozzles, achieving the same protective effect with a simpler, more direct mechanism
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 enhances printing reliability during speed changes by preventing ink drying and ensuring consistent ink ejection, allowing for uninterrupted printing during ramps without data loss, even with quick-drying inks, at low costs.
Implementation Method 1
The activators can generate ink droplets piezoelectrically
Implementation Method 2
the piezoelectric activators of the nozzles are respectively vibrated before or after the printing process (also called prefire or meniscus vibrations), such that no ink droplets are ejected but the ink in the nozzles is stirred
Data Source
AI summary
In a method to execute a print interruption, a printing substrate is printed to with a printing unit with at least one print head. With aid of a sensor, print clock pulses are generated that are supplied to a print controller depending on a feed of the printing substrate. With triggering of the print interruption, a feed speed of the printing substrate is reduced from a print speed in the printing operation to a predetermined speed according to a deceleration ramp. After the print interruption the printing substrate is accelerated again to the print speed according to an acceleration ramp. Given occurrence of a print clock pulse during at least one of the ramps, the print controller sends at least one vibration pulse to the at least one print head so that at least one cycle of vibration oscillations is implemented at the print head. The at least one vibration pulse is generated if a time interval of the print clock pulses relative to one another reaches a predetermined value.