Liquid Discharge Device Electrostatic Capacitance Level Detection
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Solution Overview
Problem
Existing liquid level detection systems in containers face accuracy issues due to fluctuations in liquid levels, affecting the precise measurement of residual quantities, especially in liquid discharge devices like inkjet printers.
Innovation Solution
A liquid discharge device with a storage section, transmission electrode, reception electrode, filter circuit, and detection circuit that removes specific frequency components from electric signals to accurately detect the liquid level and storage amount, using capacitors to determine the liquid level based on electrostatic capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrostatic capacitance measurement is used to detect liquid level, then liquid level detection is enabled, but detection accuracy deteriorates due to liquid level fluctuations
Solution Approach 1:
The patent applies dynamics by making the guard electrode potential variable rather than fixed. The control circuit dynamically adjusts the guard electrode potential to follow the liquid level changes, transforming the static reference potential into a dynamic one that adapts to fluctuations. This resolves the contradiction by maintaining measurement accuracy despite liquid level variations.
Solution Approach 2:
The patent changes the parameter of guard electrode potential from constant to variable. By modifying the electrical parameter (potential) of the guard electrode based on liquid level position, the system compensates for fluctuations and maintains accurate capacitance measurement, thereby improving both measurement precision and detection stability.
2Measurement precision
If simple electrostatic capacitance measurement is used, then device complexity is reduced, but detection accuracy deteriorates due to noise and fluctuations
Solution Approach 1:
The patent introduces a guard electrode as an intermediary element between the detection electrode and the liquid level fluctuations. This guard electrode acts as a mediator that shields the detection electrode from the harmful effects of liquid level changes, improving measurement accuracy while adding only moderate complexity to the device structure.
Solution Approach 2:
The patent implements feedback control where the control circuit continuously monitors the liquid level and adjusts the guard electrode potential accordingly. This feedback mechanism compensates for fluctuations in real-time, significantly improving detection accuracy while the added circuit complexity remains manageable due to the straightforward feedback loop design.
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
The system enhances detection accuracy by filtering noise caused by liquid level fluctuations, ensuring precise measurement of the liquid level and preventing ink depletion in inkjet printers.
Implementation Method 1
residual quantity of the contents of the container is detected based on electrostatic capacitance measured by the detection electrode
Implementation Method 2
a filter circuit that removes a predetermined frequency component from an electric signal supplied from the reception electrode
Data Source
AI summary
A liquid discharge device includes a discharge section that discharges a liquid, a storage section that includes a first surface and a second surface separated from the first surface in a first direction, and is configured to store the liquid between the first surface and the second surface, a transmission electrode that is provided on the first surface, a reception electrode that is provided on the second surface, a filter circuit that removes a predetermined frequency component from an electric signal supplied from the reception electrode, and a detection circuit that detects a storage amount of the liquid stored in the storage section based on an output from the filter circuit.