Piezoelectric Liquid Sensor Cavity Flow Paths
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Solution Overview
Problem
Conventional liquid sensors for inkjet apparatuses face issues with air bubbles entering the cavity, leading to erroneous judgments about ink levels, and ink remaining in the cavity, causing inaccurate detection of residual ink amounts.
Innovation Solution
A liquid sensor with a specific cavity shape and integrated piezoelectric element, including a vibration cavity forming base portion and a flow path forming base portion, prevents air bubbles and ink from staying in the cavity by using a liquid supply and discharge path configuration, ensuring accurate detection of liquid presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional piezoelectric device with an exposed cavity is used to detect residual ink, then the resonant frequency can be measured to determine ink levels, but air bubbles enter the cavity causing erroneous detection judgments
Solution Approach 1:
A liquid supply path and liquid discharge path are introduced as intermediary structures to control liquid flow into and out of the cavity. The liquid supply path allows ink to enter the cavity for detection, while the liquid discharge path enables air bubbles and excess ink to be expelled, ensuring the cavity contains only the intended liquid sample for accurate and reliable detection.
Solution Approach 2:
The liquid discharge path is designed to preliminarily remove air bubbles and excess ink from the cavity before the actual detection process. By establishing a flow path that actively discharges unwanted substances, the system ensures the cavity is properly prepared with only the necessary liquid sample, preventing erroneous detection judgments.
2Measurement precision
If a conventional piezoelectric device with an exposed cavity is used, then ink level can be detected, but ink remains in the cavity causing inaccurate detection of residual ink amounts
Solution Approach 1:
The liquid discharge path serves as an intermediary mechanism to remove excess ink and residues from the cavity after detection. This flow path ensures complete evacuation of liquid from the cavity, preventing ink residue that would otherwise interfere with subsequent detection cycles and cause inaccurate measurements of residual ink amounts.
Solution Approach 2:
The liquid discharge path actively extracts and removes excess ink and air bubbles from the cavity. By providing a dedicated egress path for liquid removal, the system ensures the cavity is thoroughly cleared of any remaining ink after the detection process, enabling accurate detection of residual ink levels in the main reservoir without contamination from cavity residues.
3Reliability
If two electrodes are mounted for liquid surface detection, then the actual amount of ink can be detected with high reliability, but the seal structure becomes complicated and manufacturing cost runs up
Solution Approach 1:
The detection function is merged with the existing piezoelectric actuator structure. The same piezoelectric element that generates vibration for ink jetting is also used to detect resonant frequency changes for ink level measurement. This integration eliminates the need for separate detection electrodes and their associated seal structures, reducing device complexity while maintaining detection reliability through non-contact electromagnetic coupling.
Solution Approach 2:
The piezoelectric element is designed to serve multiple functions: it acts as both the actuator for generating ink droplets and the sensor for detecting ink levels through resonant frequency measurement. This multi-functionality eliminates the need for additional dedicated detection components, simplifying the overall structure and reducing manufacturing complexity while maintaining high reliability in ink amount detection.
4Measurement precision
If two electrodes are mounted for liquid surface detection, then actual ink amount can be detected, but manufacturing steps are increased and manufacturing cost runs up
Solution Approach 1:
The detection functionality is merged into the existing piezoelectric actuator manufacturing process. By using the same piezoelectric element for both actuation and detection, the number of manufacturing steps is reduced. The integration eliminates the need for separate electrode mounting, alignment, and sealing operations, making the manufacturing process simpler and more cost-effective while maintaining precise ink amount detection capability.
Solution Approach 2:
The complex two-electrode detection system is extracted and replaced with a simplified single-element system. By removing the need for additional detection electrodes and their associated mounting and sealing steps, the manufacturing process becomes more straightforward and easier to automate, reducing both manufacturing complexity and cost while preserving detection precision through resonant frequency measurement.
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 reliably determines the presence of liquid, preventing air bubbles and ink residue, thus enhancing the accuracy of ink level detection and reducing manufacturing costs by simplifying the sensor design.
Implementation Method 1
a piezoelectric element including a first electrode formed at a side of a second surface of the vibration cavity forming base portion, a piezoelectric layer laminated on the first electrode, and a second electrode laminated on the piezoelectric layer
Data Source
AI summary
The invention relates to a liquid sensor which can certainly judge the existence of liquid, and a liquid container including the sensor. A liquid sensor 60 in which a piezoelectric element having a piezoelectric layer 47 on both surfaces of which electrodes 46 and 49 are formed is used, and a bottom 43a of a cavity 43 for receiving liquid as a detection object is vibrated. The sensor 60 includes a vibration cavity forming base portion 40 in which the cavity 43 having the vibratable bottom 43a is formed, and a flow path forming base portion 50 laminated on the vibration cavity forming base portion 40. A liquid supply path 53 for supplying the liquid as the detection object to the cavity 43 and a liquid discharge path 54 for discharging the liquid as the detection object from the cavity 43 are formed in the flow path forming base portion 50.