MEMS Microphone Self-Vibration Calibration Without Test Sound
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Solution Overview
Problem
Existing microphones require a sound source to set correction values for acoustic characteristics, limiting their ability to function without a test sound source.
Innovation Solution
A microphone with a vibration device that outputs an electric signal corresponding to acoustic pressure, a drive unit to vibrate the device, and a correction unit to calculate correction values based on the output signal, allowing for correction value calculation without a sound source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sound source is used to set correction values, then the correction accuracy can be improved, but the system requires additional equipment and cannot function without a test sound source
Solution Approach 1:
The vibration device serves dual purposes: it acts as both the actuator to generate acoustic pressure and the sensor to detect the acoustic pressure. By using the same device for both driving and detection, the system eliminates the need for separate sound source equipment while maintaining correction accuracy.
Solution Approach 2:
The vibration device is designed to perform multiple functions: it can be driven by the drive unit to generate acoustic pressure for correction value calculation, and simultaneously function as the detection device to output the electric signal corresponding to the acoustic pressure. This multi-functionality resolves the contradiction by eliminating the need for separate sound source equipment.
2Measurement precision
If a separate sound source is used for correction, then correction values can be obtained, but the system becomes dependent on external sound source characteristics
Solution Approach 1:
The system uses its own vibration device for both generating and detecting acoustic pressure, making the correction value calculation independent of external sound source characteristics. The vibration device self-services as both actuator and sensor, eliminating dependency on external equipment.
Solution Approach 2:
Instead of using a separate sound source to drive the diaphragm and a separate microphone to detect the pressure, the invention inverts the approach by using the same vibration device to both drive the diaphragm and detect the resulting acoustic pressure through its output signal.
3Ease of operation
If the vibration device is used for both driving and detection, then the system can function without a sound source, but the device complexity increases
Solution Approach 1:
The vibration device is designed as a multi-functional component that can operate as both the actuator (when driven by the drive unit) and the sensor (when outputting the electric signal). This universal design enables the system to function without external sound source equipment while integrating both functions into a single device.
Solution Approach 2:
The invention merges the driving function and detection function into a single vibration device. By combining these two functions that were previously performed by separate devices (sound source and microphone), the system achieves ease of operation without external sound sources while managing device complexity through integration.
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
Enables the calculation of correction values independently of sound source characteristics, improving the microphone's functionality and accuracy in acoustic characteristic correction.
Implementation Method 1
a vibration device that outputs a first electric signal corresponding to an acoustic pressure
Implementation Method 2
a drive unit that vibrates the vibration device by a drive signal
Data Source
AI summary
A microphone has a MEMS device, a driver, and a control unit. The MEMS device outputs a first electrical signal according to an acoustic pressure. The driver vibrates the MEMS device by a drive signal. The control unit calculates a correction value for correcting the first electric signal based on a second electric signal output from the MEMS device when the MEMS device is vibrated by the drive signal.