Continuous Inkjet Drop Charge Control for High-Speed Printing
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Solution Overview
Problem
Continuous Ink Jet (CIJ) printers face challenges in maintaining print quality at high speeds due to aerodynamic perturbations, especially when printing on non-flat surfaces like cables, bottles, or extruded products, as the number of drops generated is insufficient, leading to skewed characters.
Innovation Solution
A method and printer system that determine whether drops are protected from aerodynamic perturbations, adjusting their charge data accordingly to ensure proper printing, using two sets of charge data for protected and non-protected drops, and switching between these sets as needed during the printing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If printing speed is increased to improve productivity, then the number of drops generated becomes insufficient and aerodynamic perturbations cause skewed characters, but maintaining drop protection requires preceding drops which reduces the effective number of printable drops
Solution Approach 1:
The patent changes the charge parameter of drops dynamically based on their position in the sequence. Drops that are not protected by preceding drops receive a first charge value, while protected drops receive a second charge value. This parameter change allows the system to maintain precise character alignment at high printing speeds by compensating for aerodynamic perturbations only where necessary, thus resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent applies different charge characteristics to different drops based on their local context in the drop sequence. Unprotected drops (at the beginning of character sequences or after gaps) receive different charging than protected drops (followed by sufficient preceding drops). This local differentiation ensures that only the necessary compensation is applied, maintaining precision without unnecessarily reducing the effective number of printable drops.
2Manufacturing precision
If more preceding drops are added to protect from aerodynamic perturbations, then character alignment improves, but the number of printable drops decreases and printing efficiency reduces
Solution Approach 1:
Instead of adding more preceding drops, the patent changes the charge parameter of existing drops based on whether they are protected or not. This allows the system to maintain character alignment precision through parameter adjustment rather than increasing the number of protective drops, thereby preserving printing efficiency while achieving the desired precision.
Solution Approach 2:
The patent creates a model of aerodynamic perturbation effects and applies compensatory charge values based on this model. By copying the expected perturbation pattern and pre-compensating with appropriate charge values, the system achieves accurate character alignment without needing additional preceding drops, thus maintaining printing efficiency.
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 improves print quality by ensuring that drops are adequately charged to maintain their trajectory and alignment, even at high speeds and on complex surfaces, reducing the occurrence of skewed characters.
Implementation Method 1
Any drop generator, in particular those implementing piezo-electric devices, works at a fixed frequency
Implementation Method 2
The drops are thus generated at a constant rate... charging each drop according to whether it is protected from said perturbations or not protected from said perturbations
Implementation Method 3
aerodynamic perturbations (aerodynamic interactions between drops and with their environment) interfere with the drops trajectories
Data Source
AI summary
A method for forming at least one plurality of printed dots on a surface, with help of at least one plurality of drops generated by a printhead of a continuous inkjet printer. The method comprises, for each plurality of printed dots: deciding, whether all drops of the at least one plurality of drops are protected from perturbations due to the air resistance or whether at least one drop of the at least one plurality of drops is not protected from the perturbations; generating and charging each drop of the at least one plurality of drops according to whether it is protected from the perturbations or not protected from the perturbations; and printing the at least one plurality of drops on the surface.