Capacitive Sensor Array for Ink Level and Alignment Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing inkjet printers lack an effective means to accurately determine the liquid level in the service module and ensure correct alignment, leading to potential leaks and damage due to misalignment, with existing solutions providing low resolution and discrete level indications.
Innovation Solution
A capacitive liquid level sensing system using an array of identical sensors arranged to capture a continuous characteristic of the liquid level, with processing to derive the level from capacitance measurements and residual comparisons for alignment verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a service module is connected to the ink circuit through non-drip valves, then ink spillage is reduced, but misalignment between valve parts may still result in leaks
Solution Approach 1:
The patent performs alignment verification before the ink system starts operating. The processing facility compares residual values from capacitance measurements to determine if the service module is correctly aligned, preventing misalignment issues before they cause leaks or damage to printer components.
2Device complexity
If capacitance sensing is used to indicate ink level, then cost and complexity are reduced, but level indications are provided only in discrete steps at low resolution
Solution Approach 1:
The patent divides the sensing task among multiple sensors (at least three sensors) arranged in an array. Each sensor measures capacitance at a different position, and the processing facility combines these measurements to generate a continuous characteristic, achieving high-resolution level indication while keeping individual sensors simple and low-cost.
Solution Approach 2:
The patent combines measurements from multiple sensors to create a continuous ink level characteristic. The processing facility integrates the discrete capacitance readings from individual sensors into a smooth, continuous level indication, resolving the contradiction between simple sensing and precise measurement.
3Reliability
If the ink level is allowed to get too low, then the system may shut down to protect components, but air may be drawn into the system potentially damaging the pump and other components
Solution Approach 1:
The patent implements continuous monitoring of ink level through capacitance sensing and provides feedback to the control system. The processing facility tracks the continuous ink level characteristic and can alert users or automatically control the ink system to prevent air from being drawn into the pump and other components, ensuring timely refilling before damage occurs.
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
Provides accurate, continuous liquid level monitoring and alignment detection, preventing leaks and ensuring proper operation by identifying misalignment issues before starting the ink system, thus protecting printer components.
Implementation Method 1
measuring a capacitance associated with each sensor
Data Source
AI summary
The invention describes a facility to provide an indication of level in a container of conductive liquid used in an inkjet printer. The facility comprises an array of nested capacitive sensor pads, the outputs of which can be processed to provide a continuous indication of level. The outputs can also be processed to provide an indication of whether the container is mis-aligned on the printer.