Liquid Tank Capacitance Sensor for Inkjet Apparatus
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Solution Overview
Problem
Inkjet image forming apparatuses face inefficiencies in liquid consumption and contamination prevention due to the design of liquid tanks, where the outflow port is below the liquid level, leading to increased remaining liquid and potential contamination when the tank is deemed empty.
Innovation Solution
The design incorporates an electrostatic capacitance sensor that detects changes in capacitance between the tank's side surface and the ground to determine liquid quantity, with a supply port formed below the liquid level, and features a container body with through-holes or solid leg parts to minimize remaining liquid, ensuring accurate detection and reducing waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outflow port is disposed below the liquid level at the time of emptying to prevent air from entering, then air entry is prevented, but the quantity of remaining liquid increases and liquid cannot be consumed efficiently
Solution Approach 1:
The container body is divided into a liquid storage space and a blank part (air cushion space) separated by a liquid level. The outflow port is positioned in the blank part above the liquid level at emptying, while the electrostatic capacitance sensor is placed to detect liquid level changes. This segmentation allows the outflow port to remain above liquid level (preventing air entry) while minimizing remaining liquid through the blank part design.
Solution Approach 2:
The electrostatic capacitance sensor detects liquid level changes before the liquid actually reaches the outflow port, providing advance warning that the liquid is nearing depletion. This preliminary detection allows the system to determine emptying status proactively, ensuring the outflow port remains above liquid level while minimizing waste through precise monitoring.
2Measurement precision
If the electrostatic capacitance sensor is placed close to the ground surface for detection, then detection sensitivity improves, but the top surface and ground surface electrical conductivity may interfere with detection accuracy
Solution Approach 1:
The container body acts as an intermediary between the electrostatic capacitance sensor and the ground surface. The sensor detects capacitance changes through the container wall and liquid, using the container body as a mediator that isolates the detection circuit from direct electrical interference with the ground surface, while still allowing capacitance-based liquid level detection to function accurately.
Solution Approach 2:
The patent replaces direct electrical contact detection methods with electrostatic capacitance sensing. Instead of using electrical contacts that would be susceptible to ground interference, the system uses non-contact electrostatic field sensing through the container wall, substituting mechanical/electrical contact with field-based detection that is less susceptible to electrical interference.
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 configuration allows for precise detection of the remaining liquid, minimizing waste and preventing contamination by accurately determining when the tank is empty, thus optimizing liquid consumption and maintenance.
Implementation Method 1
The electrostatic capacitance sensor detects a change in capacitance between a side surface of the container body and the ground surface to determine a change in quantity of the liquid in the container body
Data Source
AI summary
An image forming apparatus includes a housing, a container body, and an electrostatic capacitance sensor. The container body contains a liquid and is placed on a ground surface which is a part of the housing. The electrostatic capacitance sensor detects a change in capacitance between a side surface of the container body and the ground surface to determine a change in quantity of the liquid in the container body. The top surface of the container body is a part of the housing. The top surface and the ground surface are in electrically conductive state, a distance between the top surface and the electrostatic capacitance sensor is longer than a distance between the ground surface and the electrostatic capacitance sensor, or the top surface and the ground surface are electrically insulated, or the top surface is opened.