Humidity Detection in Liquid Ejecting Heads via Interlayer Resistance
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Solution Overview
Problem
Existing liquid ejecting heads do not effectively acquire humidity information near the piezoelectric actuator, leading to potential performance deterioration due to humidity influences.
Innovation Solution
A liquid ejecting head is designed with a piezoelectric element, a vibration plate, and a pressure chamber substrate, along with an interlayer whose resistance changes with humidity, and detection electrodes to accurately measure humidity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a humidity sensor is provided in a space inside the case portion (related art approach), then humidity information can be acquired, but the measurement precision is insufficient because the sensor is not positioned optimally near the piezoelectric actuator
Solution Approach 1:
The patent uses the interlayer as an intermediary medium that naturally responds to humidity changes through resistance variation. This interlayer is positioned in direct contact with the piezoelectric actuator, serving as both a structural component and a humidity sensing medium, thereby achieving precise local humidity measurement without adding separate sensor components
Solution Approach 2:
The interlayer serves multiple functions: it acts as an insulating layer for the piezoelectric actuator, a structural component of the liquid ejecting head, and simultaneously functions as a humidity sensing element through its resistance change property. This multi-functionality eliminates the need for separate humidity sensors while achieving measurement precision
2Reliability
If no specific humidity detection structure is provided (related art approach), then the device structure remains simple, but humidity information cannot be appropriately acquired leading to performance deterioration
Solution Approach 1:
The interlayer serves itself as a humidity sensing element by utilizing its inherent electrical resistance property that changes with humidity. The existing structural component (interlayer) automatically provides humidity detection functionality without requiring additional dedicated sensing structures, thereby maintaining device simplicity while ensuring actuator performance reliability
Solution Approach 2:
The system establishes a feedback mechanism where the resistance change of the interlayer due to humidity variations is detected by the detection electrodes, and this information is used to monitor and manage the humidity environment of the piezoelectric actuator, enabling proactive performance maintenance
3Measurement precision
If detection electrodes are placed to directly contact the interlayer, then humidity measurement precision is improved, but the device complexity increases due to additional electrode structures
Solution Approach 1:
The detection electrodes are integrated with the existing electrode structures of the piezoelectric actuator system. The first detection electrode is arranged on the same side as the drive electrodes, and the second detection electrode is arranged on the opposite side, merging the humidity detection function with the existing electrical structure rather than adding separate external sensing components
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 solution enables precise detection of humidity levels, allowing for effective management of humidity's influence on the piezoelectric element and adjacent components, thereby maintaining optimal performance.
Implementation Method 1
a piezoelectric element that 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
Implementation Method 2
an interlayer that is laminated on at least one of the piezoelectric body, the vibration plate, or the pressure chamber substrate and of which resistance changes according to humidity
Data Source
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AI summary
A liquid ejecting head (510) includes: a piezoelectric element (300) that includes a first drive electrode (60), a piezoelectric body (70), and a second drive electrode (80) in a lamination direction; a vibration plate (50) 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 (10) 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 (12); an interlayer (215) that is laminated on at least one of the piezoelectric body, the vibration plate, or the pressure chamber substrate and of which resistance changes according to humidity; a first detection electrode (211) that is in contact with the interlayer; and a second detection electrode (212) that is in contact with the interlayer and faces the first detection electrode.