Electrostatic Printer Drop Placement Error Reduction
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Solution Overview
Problem
Conventional continuous inkjet (CIJ) printers face challenges with electrostatic crosstalk between adjacent nozzles, leading to reduced print resolution and drop placement errors due to the requirement for individually addressable charge electrodes, which increases complexity and sensitivity to variations in electrode alignment and ink properties.
Innovation Solution
The solution involves arranging nozzles into interleaved groups with a timing delay device to shift the timing of drop formation waveforms, using a common charge electrode at a constant potential to control breakoff lengths, and employing a deflection mechanism to separate print and non-print drops, thereby minimizing electrostatic interactions and increasing the distance between print drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individually addressable charge electrodes are used for each nozzle, then electrostatic crosstalk between adjacent nozzles is reduced, but device complexity and sensitivity to variations in electrode alignment and ink properties increase
Solution Approach 1:
The patent merges multiple individually addressable charge electrodes into a single common charge electrode that serves all nozzles simultaneously. This common electrode is positioned to interact with drops from multiple nozzles, eliminating the need for separate electrodes for each nozzle while maintaining control over drop charging. The merging reduces device complexity and eliminates sensitivity to individual electrode alignment variations.
Solution Approach 2:
The common charge electrode performs multiple functions: it charges drops from all nozzles in the array, provides uniform charging across the entire nozzle array, and eliminates the need for individual electrode control circuits. This universal electrode structure simplifies the overall system while maintaining precise control over drop charge for accurate placement.
2Manufacturing precision
If individually addressable charge electrodes are used for each nozzle, then electrostatic crosstalk is minimized, but sensitivity to variations in electrode alignment and ink properties increases
Solution Approach 1:
By merging all individual charge electrodes into one common electrode, the system eliminates variations in electrode alignment and ink properties that would affect individual electrode performance. The common electrode provides uniform charging conditions for all nozzles, making the system more reliable and less sensitive to manufacturing tolerances and material variations.
3Device complexity
If common charge electrode at constant potential is used, then device complexity is simplified, but control over breakoff lengths and electrostatic interactions becomes more challenging
Solution Approach 1:
The patent introduces dynamic timing control to compensate for the static nature of the common charge electrode. By varying the timing of drop formation waveforms relative to the charge electrode potential, the system dynamically controls breakoff lengths and electrostatic interactions. This dynamic approach maintains precision while preserving the simplicity of the common electrode structure.
Solution Approach 2:
The system uses periodic modulation of the charge electrode potential in synchronization with the drop formation cycle. This periodic action allows precise control over drop charging and breakoff lengths by timing the potential changes with the drop generation rhythm, maintaining manufacturing precision without increasing device complexity.
4Manufacturing precision
If nozzles are arranged with high packing density to increase resolution, then print resolution improves, but electrostatic interactions between adjacent print drops increase causing placement errors
Solution Approach 1:
The patent applies preliminary timing offsets to drop formation waveforms from adjacent nozzles, staggering the drop generation times. This preliminary action ensures that drops from adjacent nozzles are formed at different times, reducing simultaneous electrostatic interactions and placement errors while maintaining high packing density and resolution.
Solution Approach 2:
By dynamically adjusting the timing of drop formation waveforms, the system compensates for the increased electrostatic interactions caused by high nozzle packing density. The dynamic timing control allows precise management of drop formation sequences, maintaining placement accuracy even with closely spaced 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
This approach enhances print resolution by reducing drop-to-drop electrostatic interactions, improving drop placement accuracy, and simplifying the control of stimulation devices, allowing for longer throw distances and higher nozzle packing densities without compromising print quality.
Implementation Method 1
A common charge electrode at a constant potential is positioned to interact with liquid jets at a breakoff point common to the liquid jets
Implementation Method 2
The charged drops are then directed through a fixed electrostatic field region causing each droplet to deflect by an amount dependent upon its charge to mass ratio
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Drop formation devices are provided with a sequence of drop formation waveforms to modulate the liquid jets to selectively cause portions of the liquid jets to break off into print drops having a print drop volume Vp and non- print drops having a non-print drop volume Vnp. The print and non-print drop volumes are distinct from each other. A timing delay device shifts the timing of drop formation waveforms supplied to drop formation devices of first and second nozzle groups so that print drops from the first and second nozzle groups are not aligned relative to each other. A charging device includes a charge electrode that is positioned in the vicinity of break off of liquid jets to produce a print drop charge state on drops of volume Vp and to produce a non-print drop charge state on drops of volume Vnp.