Ink Level Sensing in Inkjet Cartridges With Low-Conductivity Ink
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Solution Overview
Problem
Ink jet recording devices face challenges in accurately detecting the remaining amount of ink due to erroneous capacitance measurements caused by ink films forming on the container walls, leading to incorrect detection of the ink liquid face height.
Innovation Solution
The device incorporates an ink composition with an electrical conductivity of 10.0 mS/cm or less, using a capacitance detection method to accurately detect the ink level by minimizing the formation of ink films on the container walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electrodes are disposed on the wall surface of the container, then the structure is simple, but the capacitance detection becomes erroneous when the wall surface is wet with ink
Solution Approach 1:
The patent extracts the electrodes from the wall surface and relocates them to the bottom surface of the container. This separation removes the source of detection error (electrodes on wet wall surfaces) while maintaining structural simplicity. The electrodes are now positioned where they can reliably detect capacitance without interference from ink films on vertical walls.
Solution Approach 2:
The patent introduces the bottom surface of the container as an intermediary platform for electrode placement. Instead of electrodes directly contacting the problematic wall surfaces, the bottom surface serves as a stable intermediary where capacitance detection occurs, eliminating the direct interaction between electrodes and ink-filmed walls.
2Reliability
If the ink composition has high electrical conductivity, then the ink jet recording performance is good, but the capacitance detection becomes erroneous due to ink films on container walls
Solution Approach 1:
The patent changes the spatial parameter of electrode placement from vertical wall surfaces to the horizontal bottom surface. This parameter change fundamentally alters the detection geometry, allowing capacitance measurement to occur at the bottom where ink films are minimal or absent, thereby enabling accurate detection even for high-conductivity inks that form prominent wall films.
3Device complexity
If the electrode position is fixed on the wall surface, then the device structure is simple, but the ink liquid face height cannot be detected correctly when walls are wet
Solution Approach 1:
The patent extracts the electrodes from the wall surface configuration and repositions them on the bottom surface. This extraction eliminates the fundamental flaw of detecting liquid face height through wet wall surfaces, while the overall device structure remains simple through this straightforward repositioning rather than complex modifications.
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 allows for precise detection of the ink liquid face height and remaining amount, reducing erroneous capacitance measurements and enhancing the accuracy of ink detection.
Implementation Method 1
a capacitance detection unit that detects the capacitance between the first electrode and the second electrode using a mutual capacity method to detect the amount of an ink remaining in the container
Implementation Method 2
the ink jet ink composition has an electrical conductivity of 10.0 mS/cm or less
Data Source
AI summary
An ink jet recording device of the present disclosure is an ink jet recording device including an ink amount detection device that includes a container internally having an accommodation space that accommodates an ink jet ink composition, a first electrode and at least one second electrode disposed to face each other via the accommodation space, and a capacitance detection unit detecting a capacitance between the first electrode and the second electrode using a mutual capacity method, in which the ink jet ink composition has an electrical conductivity of 10.0 mS/cm or less.