Piezoelectric MEMS Transducer Structure for Gas Flow Suppression
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Solution Overview
Problem
Existing MEMS transducers face issues with sound reproducibility due to excessive gas flow and warpage of the film body, which limits the amplitude of vibration and cancels the intended sound pressure.
Innovation Solution
A transducer design featuring a substrate with a film body connected to a frame body, a protrusion along the outer edge, and a lid body covering the film body, along with a protection film to enhance mechanical stability and reduce gas flow, while using a piezoelectric element for vibration control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the film body is formed as a cantilever with separated outer edge, then the film body can vibrate freely, but excessive gas flow occurs between the film body and support member which cancels sound pressure
Solution Approach 1:
The harmful gas flow is extracted and redirected through the exhaust hole provided in the support member, separating the useful vibration function from the harmful gas accumulation effect. This allows the film body to maintain vibration freedom while the gas is actively removed through a dedicated pathway.
Solution Approach 2:
The exhaust hole acts as an intermediary element between the film body and the external environment, providing a controlled pathway for gas flow that prevents pressure buildup while maintaining the cantilever's vibration capability. The hole mediates between the need for vibration freedom and the need to control gas flow.
2Extent of automation
If piezoelectric element and protection film are disposed on the film body, then the film body can be driven, but film stress causes warpage which limits vibration amplitude
Solution Approach 1:
The frame body structure serves as a counterbalancing element that compensates for the warpage induced by film stress. The rigid frame provides structural support that counteracts the bending forces from the piezoelectric element and protection film, maintaining the film body's flatness while preserving its driving capability.
3Length of moving object
If the outer edge of the film body is separated from the support member, then vibration amplitude can be maintained, but gas flow increases which deteriorates sound reproducibility
Solution Approach 1:
The harmful gas flow is extracted through the exhaust hole in the support member, removing the source of sound pressure cancellation. This allows the film body to maintain large vibration amplitude from the separated outer edge configuration while the gas flow is actively managed to prevent reproducibility deterioration.
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 design enhances sound reproducibility by suppressing gas flow and maintaining amplitude, particularly in low frequency ranges, thereby improving the overall sound pressure and reducing unwanted harmonics.
Implementation Method 1
A MEMS transducer includes a piezoelectric element and a film body driven by means of the piezoelectric element
Data Source
AI summary
A transducer includes a substrate containing silicon and a piezoelectric element disposed on the substrate. The substrate includes a film body including a first surface and a second surface facing in mutually opposite directions in a thickness direction of the substrate and a frame body surrounding the film body when the film body is viewed from the thickness direction. The piezoelectric element is disposed on the first surface of the film body. A part of an outer edge of the film body when viewed from the thickness direction forms a connection portion connected to the frame body, and a remaining part of the outer edge excluding the connection portion is separated from the frame body. The substrate includes a protrusion protruding in the thickness direction from a region including at least a part of the remaining part of the outer edge of the second surface.