Inkjet Printhead Pressure Feedback for Viscosity Control
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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 in high-throughput industrial applications.
Innovation Solution
An inkjet printing system with pressure sensors and a control unit that calculates flow resistance to adjust ink temperature for maintaining calibrated viscosity, using the Hagen-Poiseuille law and empirical models to compensate for viscosity changes and system degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inkjet printing systems use batch-manufactured inks with varying compositions, then productivity is improved through regular ink changes, but manufacturing precision deteriorates due to viscosity variations affecting printing quality
Solution Approach 1:
The system changes the temperature parameter of the ink to compensate for viscosity variations between batches. By heating the ink to different temperatures, the system adjusts the ink's physical properties to achieve a target viscosity range, allowing consistent printing quality despite compositional variations in different ink batches
Solution Approach 2:
The system uses pressure sensors to measure actual flow resistance and feeds this information back to the control unit. The control unit compares measured flow resistance against expected values and adjusts heating power accordingly, creating a closed-loop control system that maintains consistent ink viscosity and printing quality
2Manufacturing precision
If the system monitors ink viscosity to maintain consistent printing quality, then manufacturing precision is improved, but device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The system uses flow resistance as an intermediary parameter to indirectly measure ink viscosity. Instead of directly measuring viscosity with complex viscometers, the system measures pressure differential across the print head, which correlates with viscosity through flow resistance calculations, simplifying the measurement approach
Solution Approach 2:
The system replaces direct viscosity measurement mechanisms with a pressure-based measurement approach. By measuring pressure differential and calculating flow resistance, the system substitutes complex viscosity sensing with simpler pressure sensor technology, reducing device complexity while maintaining manufacturing precision
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
Ensures consistent ink viscosity and improved printing quality by dynamically adjusting ink temperature based on flow resistance measurements, reducing the need for complex degradation detection and enhancing print consistency across different ink batches.
Implementation Method 1
a heating system configured to heat the ink from the ink store to an ink jetting temperature
Implementation Method 2
the first pressure sensor being located at a fluid inlet upstream of the nozzles and being configured to detect an inlet pressure, the second pressure sensor located at a fluid outlet downstream of the nozzles and configured to detect an outlet pressure
Data Source
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 a 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 (ΔT) of the ink such that a calibrated ink viscosity (μ_ref) is obtained.