Inkjet Drop Formation Crosstalk Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In continuous inkjet printing systems, the formation of large drops is often incomplete before reaching the deflection air flow, leading to unintended merging with small drops and neighboring jets, causing disturbances and affecting print quality due to acoustic stimulation crosstalk and uneven drop spacing.
Innovation Solution
A method involving specific drop waveforms with controlled pulse energies and periods, including a small drop waveform and a large drop waveform with an additional second pulse, is used to minimize drop formation length and reduce disturbance to neighboring jets, ensuring complete coalescence before deflection and reducing satellite drop merging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single large-energy pulse is used to form large drops, then the drop volume is sufficient for printing, but the drop formation length becomes too long causing incomplete formation and unintended merging with small drops
Solution Approach 1:
The single large-energy pulse is segmented into multiple smaller pulses (first pulse and second pulse) separated by a time interval. The first pulse initiates drop formation and the second pulse completes coalescence, achieving the same large drop volume with a shorter drop formation length and preventing merging with small drops.
Solution Approach 2:
The first pulse performs the preliminary action of initiating drop formation and creating the initial large drop structure. The second pulse then completes the coalescence process, ensuring complete formation before the drops enter the deflection region, thereby preventing unintended merging.
2Productivity
If periodic heat pulses are applied at Rayleigh frequency to form drops, then drop formation is efficient, but acoustic stimulation crosstalk causes uneven spacing and unintended merging of drops from neighboring jets
Solution Approach 1:
The harmful acoustic stimulation is extracted and eliminated by using non-periodic pulse pairs instead of continuous periodic pulses. The pulse pairs are applied asynchronously to different nozzle groups, preventing the propagation of acoustic waves that cause crosstalk and uneven drop spacing while maintaining efficient drop formation.
Solution Approach 2:
Instead of using continuous periodic pulses at Rayleigh frequency that cause acoustic crosstalk, the invention uses discrete pulse pairs with specific time intervals. The pulsing scheme is applied periodically to different nozzle groups in an asynchronous manner, maintaining productivity while eliminating the harmful continuous acoustic stimulation.
3Length of moving object
If the drop formation length is reduced, then the print head size is reduced and complete large drop formation is achieved, but the pulse energy must be carefully controlled to avoid satellite drop formation
Solution Approach 1:
The pulse parameters (energy, duration, timing) are changed and optimized for the pulse pair scheme. The first pulse has specific energy characteristics to initiate formation, while the second pulse has different characteristics to complete coalescence. This parameter control ensures short drop formation length while preventing satellite drop formation and maintaining precise drop volume control.
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 results in shorter drop formation lengths, improved print head design, reduced risk of incomplete drops, and minimized disturbance to neighboring jets, enhancing print quality and data processing simplicity.
Implementation Method 1
periodic heat pulses drive capillary break-up of jets formed at each nozzle to produce an array of drops
Implementation Method 2
the jet responds most sensitively to disturbances at a characteristic frequency fR known as the Rayleigh frequency
Implementation Method 3
A gas flow directed across the stream of ink drops interacts with the stream of ink drops. This interaction deflects smaller drops more than larger drops and thereby separates ink drops having one volume from ink drops having other volumes
Implementation Method 4
Liquid is provided to the jetting module under pressure sufficient to cause a liquid stream to jet from the nozzle
Data Source
AI summary
A liquid stream is caused to jet from a nozzle. A small or large drop waveform applied to a drop forming mechanism causes the liquid stream to break up into a small or large volume drop, respectively. The small drop waveform includes a pulse having a pulse energy Es, and a period XS, where XS≈1/fR, and where fR is the Rayleigh frequency of the liquid. The large drop waveform has a period XL, where XL=NXS, with the large volume drop being N times the small volume drop. The large drop waveform includes a first pulse having a pulse energy EL1, where EL1≧ES and a second pulse occurring within a time period X2, where X2≦XS, of an initial pulse of a subsequent small or large drop waveform, the second pulse including a pulse energy EL2, where EL2<ES.