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 variations in drop charge and limited nozzle spacing, which results in reduced print resolution and increased complexity in controlling drop placement and deflection.
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 induce different charge states on print and non-print drops, and employing a deflection device to separate their paths, thereby reducing electrostatic interactions and improving drop placement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individually addressable charging electrodes are provided for each nozzle, then electrostatic crosstalk between adjacent nozzles is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
Multiple individually addressable charging electrodes are merged into a single common charging electrode that serves all nozzles simultaneously. This is achieved by providing one charging electrode positioned to charge drops from multiple nozzles, eliminating the need for separate charging electrodes for each nozzle while maintaining uniform drop charge through synchronized waveform application.
Solution Approach 2:
The single common charging electrode performs the charging function for all nozzles in the array, making it a universal charging structure. The electrode is positioned and controlled to uniformly charge drops from multiple nozzles simultaneously, reducing component count while maintaining the essential charging function across the entire nozzle array.
2Manufacturing precision
If nozzle spacing is increased to reduce electrostatic crosstalk, then drop placement accuracy is improved, but print resolution decreases
Solution Approach 1:
The timing parameters of the waveform signals applied to the common charging electrode are modified to control the exact moment of charge induction. By adjusting the timing of the waveform relative to the drop formation cycle, uniform charge is induced on drops from adjacent nozzles even when nozzles are closely spaced, preventing electrostatic crosstalk without requiring increased spacing.
Solution Approach 2:
The charging electrode is positioned and activated in advance relative to the drop ejection cycle, so that charge is induced on drops as they pass through the charging region before they are ejected. This preliminary charging action ensures uniform charge distribution on drops from adjacent nozzles, allowing close nozzle spacing while maintaining drop placement accuracy.
3Device complexity
If common charging electrode at constant potential is used, then device complexity is reduced, but electrostatic interactions between adjacent print drops increase
Solution Approach 1:
The charging electrode potential is made dynamic rather than constant, varying in time according to the drop formation cycle. The waveform timing is adjusted so that the charging electrode is active only during specific phases when drops are passing through the charging region, and inactive or at different potential during other phases. This dynamic control reduces electrostatic interactions between adjacent print drops while maintaining uniform charging.
Solution Approach 2:
The charging electrode is activated in periodic pulses synchronized with the drop formation cycle from each nozzle. By providing periodic waveform signals rather than continuous constant potential, the system achieves uniform charging on each drop while allowing electrostatic interactions to minimize between adjacent drops, as the electrode is not continuously active.
4Object-generated harmful factors
If timing delay is applied between adjacent nozzle groups, then electrostatic interactions between adjacent print drops are reduced, but control complexity increases
Solution Approach 1:
The nozzle array is segmented into multiple groups with different timing delays applied to each group. This segmentation allows independent timing control of different nozzle regions, reducing electrostatic interactions between adjacent drops from different groups while maintaining synchronized operation within each group. The timing delay is applied selectively rather than uniformly across all 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 increases the distance between adjacent print drops, decreases electrostatic interactions, and enhances drop placement accuracy, allowing for higher print resolution and reduced complexity in charge electrode structures, while maintaining long throw distances.
Implementation Method 1
using a common charge electrode at a constant potential to induce different charge states on print and non-print drops
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
AI summary
Drop formation devices are provided with drop formation waveforms to modulate liquid jets to cause portions of the liquid jets to form print drops having a jet breakoff length Lp in a print drop breakoff length range Rp and non-print drops having a jet breakoff length Lnp in a non-print drop breakoff length range Rnp. A timing delay device shifts the timing of the waveforms supplied to drop formation devices of first and second nozzle groups so that print drops formed from first and second nozzle groups are not aligned relative to each other. A charging device includes a charge electrode that is positioned relative to the breakoff length Lp and breakoff length Lnp such that there is a difference in electric field strength at the two breakoff lengths to produce a print drop charge state on print drops and a non-print drop charge state on non-print drops.