Capacitive Liquid Level Detection Circuit for Print Agent Vessels
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Solution Overview
Problem
Existing electrical circuits for detecting liquid levels in containers face challenges in accurately measuring parameters like the amount of print agent due to limitations in variable capacitance detection, especially when the liquid level is below the contact point with circuit components, and require efficient stimulus application methods.
Innovation Solution
The use of capacitive coupling between electrically conductive portions and components within the circuit, where a stimulus-induced vibration of the components varies capacitance in response to liquid presence, allowing for non-contact measurement through frequency and decay analysis, enabling accurate detection of liquid levels without direct electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct electrical connections are used for liquid level detection, then measurement capability is improved, but reliability deteriorates when liquid level is below contact point
Solution Approach 1:
The patent replaces direct mechanical/electrical contact-based liquid level detection with a capacitive coupling system. The stimulus is applied through the container wall via capacitive coupling, eliminating the need for direct electrical contacts that must be submerged in liquid. This allows reliable detection regardless of liquid level position.
2Reliability
If capacitive coupling is used for non-contact measurement, then reliability is improved, but measurement precision deteriorates without direct contact
Solution Approach 1:
The patent employs mechanical vibration of the container (or the component within it) to modulate the capacitive coupling. By vibrating the container at specific frequencies, the system creates characteristic resonance patterns and frequency responses that can be analyzed to accurately determine liquid presence and level, thereby maintaining measurement precision despite using non-contact capacitive coupling.
Solution Approach 2:
The system applies periodic vibration stimuli to the container and analyzes the periodic response characteristics. By using periodic action, the system can distinguish between different liquid levels and states through frequency and decay analysis, maintaining measurement precision while using reliable non-contact capacitive coupling.
3Measurement precision
If vibration stimulus is applied for capacitance variation, then measurement capability is improved, but energy consumption increases
Solution Approach 1:
The system uses periodic vibration stimuli rather than continuous excitation. By applying brief periodic pulses and analyzing the resonance response and decay characteristics, the system achieves accurate liquid detection with minimal energy input, rather than requiring continuous energy-consuming vibration or contact-based measurement.
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 method allows for reliable and non-invasive detection of liquid levels and presence within containers, providing accurate parameter measurement even when the liquid is below the contact point, with reduced resource consumption and avoiding interference from power supply frequencies.
Implementation Method 1
an electrically conductive component capacitively coupled to the first electrically conductive portion. The circuit may have a variable capacitance that is indicative of a parameter of the component
Implementation Method 2
a stimulus-induced vibration of the components varies capacitance in response to liquid presence, allowing for non-contact measurement through frequency and decay analysis
Data Source
AI summary
A print agent vessel is disclosed that comprises a circuit, the circuit comprising a first electrically conductive portion to couple to a first terminal of a printing device, a second electrically conductive portion to couple to a second terminal of the printing device, and an electrically conductive component capacitively coupled to the first electrically conductive portion. The circuit has a variable capacitance that is indicative of a parameter of the component.