Piezoelectric Driving Device With Substrate Bonding
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Solution Overview
Problem
Piezoelectric driving devices face challenges in achieving sufficient displacement and force generation in small spaces, particularly in robots, due to limitations in thickness and mechanical quality factor Qm, which also lead to heat generation and mechanical loss issues.
Innovation Solution
A piezoelectric driving device configuration with a vibrating plate and a piezoelectric vibrator having a substrate, first and second electrodes, and a piezoelectric body, where the thickness of the piezoelectric body is between 50 nm and 20 μm, and the substrate is bonded to the vibrating plate, enhancing the mechanical quality factor Qm and reducing heat generation by using a silicon substrate, and incorporating an insulating layer and lead electrodes to prevent electrostatic breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the piezoelectric body is made thinner to reduce device size, then the device can be housed in smaller spaces, but the force generated becomes extremely small and sufficient displacement cannot be obtained
Solution Approach 1:
The patent uses a composite structure consisting of a piezoelectric body layer formed on a substrate. The substrate (having higher mechanical quality factor Qm) is bonded to the piezoelectric body, creating a composite system that combines the piezoelectric effect with high Qm properties. This allows the piezoelectric body to be made thin for small device size while the substrate provides the necessary mechanical quality to generate sufficient force and displacement.
2Length of moving object
If the mechanical quality factor Qm is increased to increase displacement, then sufficient displacement for driving the driven member can be obtained, but the device complexity increases
Solution Approach 1:
The patent changes the key parameter of mechanical quality factor Qm by selecting specific substrate materials (such as silicon, sapphire, or diamond) that inherently possess high Qm values. This parameter change approach allows achieving sufficient displacement without complex mechanical structures, as the high Qm of the substrate directly enables larger vibration amplitudes and displacements.
3Loss of energy
If vibrations are suppressed by increasing mechanical quality factor Qm to reduce mechanical loss, then heat generation is reduced, but the device complexity increases
Solution Approach 1:
The composite structure of substrate bonded to piezoelectric body achieves high mechanical quality factor Qm through material selection rather than complex damping mechanisms. The substrate materials (silicon, sapphire, diamond) inherently provide high Qm, which suppresses mechanical loss and reduces heat generation without requiring additional complexity in the device structure.
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 allows for a smaller, more efficient piezoelectric driving device with increased mechanical strength and quality factor, reducing heat generation and mechanical loss, while maintaining sufficient force generation and durability.
Implementation Method 1
When an alternating-current voltage is applied to the diagonally provided two piezoelectric elements of the four piezoelectric elements, the two piezoelectric elements expand and contract
Implementation Method 2
the value of the mechanical quality factor Qm of the piezoelectric driving device may be made larger than that of the case without the substrate
Data Source
AI summary
A piezoelectric driving device includes a vibrating plate and a piezoelectric vibrator provided on the vibrating plate. The piezoelectric vibrator has a first electrode, a second electrode, and a piezoelectric body located between the first electrode and the second electrode, and a thickness of the piezoelectric body is within a range from 50 nm to 20 μm.