Acoustic Transducer Backplate Pressure Sensor Integration
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Solution Overview
Problem
Existing microphone assemblies with hermetically sealed cavities face challenges in accurately monitoring pressure changes within the cavity, which can affect sensor sensitivity and self-noise, leading to potential device failures and performance issues.
Innovation Solution
The implementation of a dual diaphragm acoustic transducer with a pressure sensing circuit and a Pirani gauge or integrated resonator on the backplate allows for precise monitoring of pressure within the cavity, enabling continuous adjustment of transducer specifications and detection of leaks or manufacturing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hermetically sealed evacuated cavity is used in the transducer, then sensor sensitivity is improved and self-noise is reduced, but pressure monitoring capability deteriorates and device complexity increases
Solution Approach 1:
The backplate serves dual functions: as a structural component of the transducer and as a substrate for integrating the pressure sensor. This merging of functions allows pressure monitoring to be added without significantly increasing overall device complexity, while maintaining the sensitivity benefits of the evacuated cavity.
Solution Approach 2:
The backplate is designed as a multi-functional element that provides both mechanical support for the transducer structure and houses the pressure sensing circuitry. This universal component approach enables simultaneous achievement of sensitivity improvement through evacuation and pressure monitoring capability.
2Measurement precision
If pressure monitoring is added to the transducer, then detection of leaks and manufacturing defects is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The pressure sensor is integrated into the backplate during the manufacturing process, allowing pressure monitoring capability to be built-in from the start. This preliminary integration enables detection of leaks and manufacturing defects early in production while minimizing additional manufacturing steps.
Solution Approach 2:
The pressure monitoring system provides self-diagnostic capability that automatically detects manufacturing defects and leaks without requiring external testing equipment. This self-service approach simplifies quality control processes and reduces manufacturing complexity.
3Stability of the object's composition
If the cavity pressure changes over time, then transducer performance stability deteriorates, but adding pressure sensors increases device complexity
Solution Approach 1:
The pressure sensor provides continuous feedback on cavity pressure conditions, enabling real-time monitoring of transducer performance stability. This feedback mechanism allows for detection and correction of pressure drift without requiring complex active control systems.
Solution Approach 2:
The solution replaces complex mechanical pressure regulation mechanisms with a simpler electronic sensing and monitoring system. By using electrical sensors and signal processing instead of mechanical adjustment mechanisms, device complexity is minimized while maintaining performance stability.
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 solution enhances the sensitivity and reliability of microphone assemblies by maintaining optimal pressure conditions within the cavity, reducing self-noise, and facilitating the detection of pressure-related issues, thereby improving device performance and longevity.
Implementation Method 1
a pressure sensor coupled on the backplate and configured to sense a pressure within the cavity
Implementation Method 2
an integrated resonator coupled to the backplate... the resonant frequency of the integrated resonator is dependent on the pressure in the cavity
Implementation Method 3
capacitive sensors fabricated using microelectromechanical systems (MEMS) technology
Implementation Method 4
The micro-beam resistor is configured to carry a bias current from the first terminal to the second terminal
Data Source
AI summary
Acoustic transducers for generating electrical signals in response to acoustic signals are disclosed. In some embodiments, an acoustic transducer includes an at least partially evacuated hermetically sealed cavity defined in part by a first diaphragm. The acoustic transducer also includes a backplate disposed at least partially within the cavity. The cavity having a pressure lower than atmospheric pressure. The acoustic transducer further includes a pressure sensor coupled to the backplate and configured to sense the pressure in the cavity.