Piezoelectric Liquid Sensor Cavity Design for Ink Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liquid sensors for inkjet apparatuses face issues with accurately detecting the residual amount of ink due to air bubbles and ink remaining in the cavity, leading to erroneous judgments and increased manufacturing costs, particularly with complex seal structures and limited ink detection capabilities.
Innovation Solution
A liquid sensor with a specifically designed cavity shape and piezoelectric element configuration, including a vibration cavity forming base portion and exit/entrance plate, prevents air bubbles and ink from staying in the cavity, using a symmetrical axis configuration and integral sintered construction to enhance detection accuracy and reliability.
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 and cause erroneous detection results
Solution Approach 1:
A liquid supply port is introduced as an intermediary component that allows liquid to flow through the cavity continuously. This mediator prevents air bubbles from accumulating in the cavity by maintaining liquid flow, thereby eliminating the source of detection errors while preserving the resonant frequency measurement capability
Solution Approach 2:
The cavity is transformed from a static, exposed structure to a dynamic flow-through structure. Liquid continuously enters and exits the cavity through the supply port and outlet, creating dynamic flow that prevents air bubble accumulation and meniscus formation, ensuring reliable detection throughout the ink consumption process
2Measurement precision
If the cavity is made small to improve detection accuracy, then the resonant frequency measurement becomes more precise, but air bubbles and ink remain in the cavity causing erroneous judgments
Solution Approach 1:
Hydraulic flow is introduced through the liquid supply port to continuously move liquid through the cavity. This hydraulic action prevents air bubbles from staying in the cavity by maintaining continuous liquid flow, and the outlet ensures ink does not accumulate, eliminating harmful factors while preserving the small cavity's detection precision
Solution Approach 2:
Continuous liquid flow through the cavity ensures that the cavity never becomes stagnant. The continuous action of liquid entering and exiting prevents air bubble and ink accumulation, maintaining detection accuracy throughout the entire ink consumption period without requiring larger cavity dimensions
3Reliability
If two electrodes are mounted to detect liquid surface for ink consumption management, then the actual amount of ink can be detected with high reliability, but the seal structure becomes complicated and manufacturing cost increases
Solution Approach 1:
The liquid supply port is extracted as a separate functional component that handles liquid flow independently. This extraction allows the detection function to focus solely on resonant frequency measurement while the supply port manages liquid delivery, simplifying the overall structure by separating detection and fluid handling functions
Solution Approach 2:
The cavity serves multiple functions: it acts as both the detection chamber for resonant frequency measurement and the flow path for liquid supply. This multi-functionality eliminates the need for separate seal structures, as the same cavity space is utilized for both detection and fluid transport, reducing device complexity while maintaining detection reliability
4Reliability
If a noble metal electrode is used for superior conductivity and corrosion resistance, then detection reliability improves, but the manufacturing cost of the ink cartridge runs up
Solution Approach 1:
The electrical detection method using noble metal electrodes is replaced with a mechanical vibration-based detection method using the piezoelectric element. The piezoelectric element detects ink levels through resonant frequency changes of the liquid meniscus, eliminating the need for expensive noble metal electrodes while maintaining detection reliability through physical rather than electrical interaction
Solution Approach 2:
The piezoelectric element is used as a cost-effective alternative to expensive noble metal electrodes. While piezoelectric materials have limited lifetimes, they are sufficiently durable for the intended application and can be replaced more economically than noble metal electrodes, reducing manufacturing costs while maintaining adequate detection performance
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 effectively prevents air bubbles and ink from accumulating in the cavity, improving the reliability of ink detection and reducing manufacturing costs by simplifying the sensor design and enhancing the accuracy of residual ink determination.
Implementation Method 1
the resonant frequency of a residual vibration signal generated by the residual vibration (free vibration) of a vibration portion of the piezoelectric device after it is forcibly vibrated by a drive pulse
Implementation Method 2
the resonant frequency of a residual vibration signal generated by the residual vibration (free vibration) of a vibration portion
Implementation Method 3
after it is forcibly vibrated by a drive pulse
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. The liquid sensor has: a vibration cavity forming base portion 40 having a first surface and a second surface opposite to each other, in which a cavity 43 for receiving liquid as a detection object is opened at a side of the first surface, and a bottom of the cavity 43 is capable of vibrating; and a piezoelectric element including a first electrode 46 formed at a side of the second surface of the vibration cavity forming base portion, a piezoelectric layer 47 laminated on the first electrode, and a second electrode 49 laminated on the piezoelectric layer. A shape of the cavity 43 in a plan view has a longitudinal dimension and a lateral dimension smaller than the longitudinal dimension.