Liquid Ejecting Head With Capacitive Humidity Sensing
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Solution Overview
Problem
Existing liquid ejecting heads face performance deterioration due to humidity influence on piezoelectric actuators and surrounding components, lacking effective humidity sensing structures.
Innovation Solution
Incorporation of a capacitance-type humidity sensor with interlayers that change capacitance based on humidity, coupled with a temperature sensor to monitor and manage humidity and temperature effects on piezoelectric elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a humidity sensor is provided in a space inside the case portion, then humidity information can be acquired, but the structure becomes complex and the sensor may not accurately reflect humidity at the piezoelectric actuator location
Solution Approach 1:
The patent merges the humidity sensing function with existing structural components (the interlayer and detection electrodes) rather than using a separate dedicated humidity sensor. The interlayer is laminated on existing components and serves dual purposes as both a structural element and a humidity-sensitive element, eliminating the need for additional sensor housing and reducing overall device complexity while maintaining measurement accuracy at the piezoelectric actuator location.
Solution Approach 2:
The patent introduces an interlayer as an intermediary element that is laminated on the piezoelectric body, vibration plate, or pressure chamber substrate. This interlayer contains humidity-sensitive materials and works in conjunction with detection electrodes to measure humidity directly at the piezoelectric actuator location, serving as a mediator between the piezoelectric components and the humidity measurement function.
2Device complexity
If no specific humidity sensor structure is adopted, then the device structure remains simple, but humidity information at the piezoelectric actuator cannot be appropriately acquired
Solution Approach 1:
The patent combines the humidity sensing function with existing structural components by laminating an interlayer containing humidity-sensitive materials on the piezoelectric body, vibration plate, or pressure chamber substrate. This integration allows humidity information to be acquired directly at the piezoelectric actuator location without adding complex dedicated sensor structures, thus preventing information loss while maintaining structural simplicity.
Solution Approach 2:
The interlayer serves multiple functions: it provides structural support, electrical insulation, and humidity sensing capability. The detection electrodes are also multi-functional, serving both as part of the piezoelectric actuator structure and as humidity detection elements. This multi-functionality ensures humidity information is captured without requiring separate dedicated sensor systems.
3Reliability
If an interlayer with humidity-sensitive capacitance is laminated on piezoelectric components, then humidity monitoring is enabled, but the device structure becomes more complex
Solution Approach 1:
The patent merges the humidity-sensitive interlayer with existing piezoelectric components through lamination, creating an integrated structure where the interlayer becomes part of the overall component assembly. This approach enables humidity monitoring to ensure piezoelectric actuator performance stability while incorporating the monitoring function into the existing structure rather than adding separate monitoring systems.
Solution Approach 2:
The patent implements a feedback mechanism where the capacitance changes of the interlayer in response to humidity variations are detected by the detection electrodes. This feedback information is used to monitor and manage the humidity environment of the piezoelectric actuator, allowing for real-time performance stability assurance through continuous humidity measurement and potential compensatory control actions.
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
Effectively monitors and manages humidity and temperature impacts, ensuring stable performance of piezoelectric actuators and components, enhancing the reliability and precision of liquid ejection.
Implementation Method 1
a piezoelectric element which includes a first drive electrode, a second drive electrode, and a piezoelectric body, the piezoelectric body being provided between the first drive electrode and the second drive electrode... a vibration plate which is provided on one side of the lamination direction with respect to the piezoelectric element and is deformed by driving of the piezoelectric element
Implementation Method 2
an interlayer which is laminated on at least one of the piezoelectric body, the vibration plate, or the pressure chamber substrate and of which capacitance changes according to humidity; a first detection electrode which is in contact with the interlayer; and a second detection electrode which is in contact with the interlayer and is disposed to be separated from the first detection electrode
Data Source
AI summary
A liquid ejecting head includes: a piezoelectric element that includes a first drive electrode, a piezoelectric body, and a second drive electrode in a lamination direction; a vibration plate that is provided on one side of the lamination direction with respect to the piezoelectric element and is deformed by driving of the piezoelectric element; a pressure chamber substrate that is provided on the one side of the lamination direction with respect to the vibration plate and is provided with a plurality of pressure chambers; an interlayer that is laminated on at least one of the piezoelectric body, the vibration plate, or the pressure chamber substrate and of which capacitance changes according to humidity; a first detection electrode that is in contact with the interlayer; and a second detection electrode that is in contact with the interlayer and is disposed to be separated from the first detection electrode.