Inkjet Printhead Flow Resistance Control for Stable Ink Viscosity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inkjet printing systems face challenges in maintaining consistent ink viscosity due to batch-to-batch variations and degradation, leading to inconsistent printing quality, especially when using porous substrates and high-throughput industrial printing.
Innovation Solution
The system monitors ink flow resistance to detect viscosity changes and adjusts ink temperature to maintain consistent viscosity by correlating flow resistance with ink viscosity using models like the Hagen-Poiseuille law and empirical models, compensating for viscosity changes by modifying ink temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inkjet printing is performed with batch-to-batch ink variations, then productivity is maintained through regular ink changes, but printing quality consistency deteriorates due to viscosity changes
Solution Approach 1:
The system changes the physical state parameter (temperature) of the ink to compensate for viscosity variations between batches. By heating or cooling the ink to a target temperature, the system adjusts the viscosity to a consistent range, ensuring printing quality remains stable even when using different ink batches with inherently different viscosities.
Solution Approach 2:
The system implements a feedback control loop where the actual ink temperature is continuously measured and compared to the target temperature. Based on this comparison, the heating/cooling mechanism adjusts the ink temperature dynamically, and the process repeats until the target temperature and corresponding viscosity are achieved, ensuring consistent printing quality.
2Ease of operation
If ink viscosity is not controlled, then ease of operation is maintained without temperature adjustment, but printing quality deteriorates due to inconsistent ink flow and droplet formation
Solution Approach 1:
The system automatically performs temperature control and viscosity compensation without requiring manual intervention. The control unit autonomously monitors ink temperature, compares it to the target, activates heating or cooling mechanisms as needed, and repeats the process until the desired viscosity is achieved, maintaining both ease of operation and printing quality consistency.
3Manufacturing precision
If ink temperature is adjusted to compensate for viscosity changes, then printing quality consistency is improved, but device complexity increases due to temperature control mechanisms
Solution Approach 1:
The system utilizes the physical property that ink viscosity changes with temperature. By controlling the temperature parameter, the system indirectly controls viscosity, achieving consistent printing quality through a well-established physical relationship rather than requiring complex direct viscosity measurement and adjustment mechanisms.
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 ensures consistent ink viscosity and improves print quality by addressing the issues of ink viscosity and substrate interaction, maintaining high throughput and reducing complexity in process control.
Implementation Method 1
A second realization is that the ink viscosity can be adjusted by modifying the ink temperature
Implementation Method 2
The flow resistance is according to the Hagen-Poiseuille law directly proportional to the dynamic ink viscosity
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an inkjet printing system (10) and method for controlling the jetting ink viscosity. A printing head (16) comprises a first pressure sensor (20) located at a fluid inlet (26) and a second pressure sensor (22) located at a fluid outlet (28). A control unit (24) is configured to retrieve the volumetric flow (Q) from 5a supply pump (18) of the inkjet printing system (10) and the inlet and outlet pressures (P_in, P_out) from the pressure sensors (20, 22). The control unit (24) is further configured to calculate an actual flow resistance (R_a) and a required temperature change (∆T) of the ink such that a calibrated ink viscosity (µ_ref) is obtained.