Piezoelectric Element Module for Ultrasonic Transducer
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Solution Overview
Problem
Ultrasonic sensors using piezoelectric elements face challenges in achieving sufficient sensitivity due to the trade-off between high piezoelectric constant d33 for transmission and high piezoelectric voltage constant g33 for reception, with existing solutions not adequately addressing this issue.
Innovation Solution
A piezoelectric element module is designed with a first piezoelectric layer having a higher d constant than a second piezoelectric layer, both on the same substrate, allowing for improved sensitivity in both transmitting and receiving units, and enabling the use of the module in ultrasonic transducers and liquid ejecting heads for varying droplet sizes with the same drive waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If PZT with high piezoelectric constant d33 is used for transmitting unit, then transmission performance is improved, but reception performance deteriorates due to small piezoelectric voltage constant g33
Solution Approach 1:
The invention divides the piezoelectric elements into two segments: transmitting units using PZT with high d33 for optimal transmission performance, and receiving units using PZT with high g33 for optimal reception performance. This segmentation allows each unit to be optimized for its specific function, resolving the contradiction between transmission and reception performance.
Solution Approach 2:
The invention applies different material properties to different locations within the sensor array. Transmitting units are configured with piezoelectric elements having high d33 constants, while receiving units are configured with piezoelectric elements having high g33 constants. This local differentiation of material properties enables simultaneous optimization of both transmission and reception functions.
2Ease of manufacture
If the same piezoelectric elements are used for both transmitting and receiving units, then manufacturing complexity is reduced, but sensitivity of both units deteriorates
Solution Approach 1:
The invention implements local quality by configuring different piezoelectric element properties in different functional units. Transmitting units use elements optimized for transmission (high d33), while receiving units use elements optimized for reception (high g33). This localized differentiation improves sensitivity for both functions while maintaining a unified sensor structure that is still relatively easy to manufacture.
Solution Approach 2:
The invention changes the piezoelectric parameters (d33 and g33 constants) of the elements used in different units. By selecting piezoelectric materials or configurations with different parameter optimizations, the system achieves improved sensitivity for both transmitting and receiving functions while maintaining manufacturing feasibility through parameter variation rather than structural complexity.
3Force
If piezoelectric elements with high d33 are used, then amplitude vibration upon voltage application increases, but piezoelectric voltage constant g33 decreases, reducing voltage generation upon pressure application
Solution Approach 1:
The invention segments the piezoelectric element functionality by using different element types for transmission and reception. Elements with high d33 are deployed in transmitting units to maximize amplitude vibration upon voltage application, while elements with high g33 are deployed in receiving units to maximize voltage generation upon pressure application. This segmentation resolves the inverse relationship between these two piezoelectric constants.
Solution Approach 2:
The invention applies local quality by assigning different piezoelectric properties to different functional locations. Transmitting units are equipped with elements having high d33 for strong mechanical response to voltage, while receiving units are equipped with elements having high g33 for strong electrical response to mechanical stress. This localized property assignment simultaneously optimizes both force generation and voltage generation characteristics.
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
This configuration enhances the sensitivity of both transmitting and receiving units, facilitating the precise ejection of droplets of different sizes in liquid ejecting heads while maintaining efficient ultrasonic wave transmission and reception.
Implementation Method 1
a first piezoelectric element having a first piezoelectric layer... the first piezoelectric layer has a d constant greater than a d constant of a second piezoelectric layer
Implementation Method 2
a second piezoelectric element having a second piezoelectric layer different from the first piezoelectric layer... the first piezoelectric layer has a g constant smaller than a g constant of the second piezoelectric layer
Data Source
AI summary
A first piezoelectric element having a first piezoelectric layer and a second piezoelectric element having a second piezoelectric layer, which is different from the first piezoelectric layer, are included on the same substrate. The first piezoelectric layer has a d constant greater than a d constant of the second piezoelectric layer.