Inkjet Print Head Fluid Chamber State Detection
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Solution Overview
Problem
Existing methods for determining the operating state of an inkjet fluid chamber are prone to noise and measurement imperfections, leading to incorrect determinations of whether the chamber is in an operative or inoperative state, and require lengthy signal processing, which is undesirable for timely decision-making in inkjet printing.
Innovation Solution
A method using a pressure wave generated by an electromechanical transducer, such as a piëzo-actuator, is employed to detect the operating state of the fluid chamber by analyzing the resonance frequencies of the pressure wave through wavelet transformation, allowing for quick and reliable determination of the chamber's state using a wavelet window that isolates the resonance frequency, thereby reducing noise influence and processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If suitable signal processing is applied to decrease incorrect determinations, then measurement precision is improved, but processing time increases
Solution Approach 1:
A reference pressure wave is obtained in advance from an undisturbed fluid chamber and stored for later comparison. This preliminary preparation eliminates the need for complex real-time signal processing during actual detection, as the reference data is already available for immediate comparison with detected pressure waves, thus reducing processing time while maintaining determination accuracy.
Solution Approach 2:
The method extracts and compares specific characteristic features of the pressure wave (such as amplitude, frequency, and temporal decay patterns) rather than processing the entire signal. By focusing only on the relevant distinguishing features that indicate chamber disturbances, the processing complexity is reduced while maintaining sufficient accuracy for reliable determination.
2Loss of time
If a quick comparison method is used, then processing time is reduced, but measurement precision deteriorates
Solution Approach 1:
The reference pressure wave characteristics are predetermined and stored beforehand. During actual operation, only a simple comparison with this pre-established reference is needed, enabling quick determination without complex real-time analysis, thus achieving both speed and accuracy.
3Measurement precision
If the detection method is made sensitive to detect disturbances, then measurement precision is improved, but reliability deteriorates due to noise and measurement imperfections
Solution Approach 1:
The method dynamically adapts the detection threshold and comparison criteria based on the characteristics of the reference pressure wave. Rather than using fixed sensitivity levels, the system adjusts its detection parameters to match the actual pressure wave behavior, allowing it to distinguish between genuine disturbances and normal variations caused by noise or measurement imperfections.
Solution Approach 2:
The comparison between detected pressure waves and the reference pressure wave provides feedback that allows the system to distinguish between actual disturbances and measurement noise. By analyzing deviations from the reference pattern, the system can reliably determine whether a detected anomaly represents a true chamber disturbance or merely measurement imperfection.
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 enables rapid and accurate assessment of the fluid chamber's state, allowing for immediate decision-making to cancel or redirect droplet ejection, thereby ensuring print quality and efficiency in inkjet printing.
Implementation Method 1
an electromechanical transducer such as a piëzo-element is used to generate a pressure change in the fluid chamber
Implementation Method 2
If a pressure wave, such as an acoustic wave, is introduced in the fluid chamber, the pressure wave will reflect and damp in the fluid chamber over time
Implementation Method 3
the pressure wave will reflect and damp in the fluid chamber over time
Data Source
Figure 1~2B
Figure 2C~3B
Figure 3C~4B
AI summary
In a method for detecting an operating state of at least one fluid chamber of an inkjet print head, after having generated a pressure wave in the fluid chamber a resulting pressure wave in the fluid chamber is detected. A detection signal corresponding to the detected pressure wave is then generated and a state indicator is determined from the detection signal using a wavelet window, the state indicator being suitable for deriving an operating state of the fluid chamber. This method enables reliable state detection. In an embodiment, it is enabled to perform the state detection between subsequent droplet ejections, thereby obtaining a highly reliable inkjet process.