Piezoelectric Speaker as Microphone for Power Reduction
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Solution Overview
Problem
Capacitive microphones in mobile devices consume significant power, limit audio performance, especially for high-volume sounds, and increase device cost when dual microphones are used to address these issues.
Innovation Solution
Incorporating a piezoelectric speaker that can function as a microphone, allowing the device to select between the speaker and microphone based on sound characteristics, thereby reducing power consumption and enhancing audio performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive microphones are used to detect sound in mobile devices, then voice activation commands can be sensed, but significant power is consumed reducing battery life
Solution Approach 1:
The piezoelectric speaker is designed to perform dual functions: serving as a sound output device and as a sound detection device (microphone). By incorporating piezoelectric material in the speaker diaphragm, the same component can transduce electrical signals to sound (speaker function) and sound waves back to electrical signals (microphone function), eliminating the need for a separate always-on capacitive microphone and reducing power consumption during sleep mode
Solution Approach 2:
The piezoelectric speaker serves itself by detecting sound waves incident on its diaphragm through the piezoelectric effect, generating electrical signals without requiring external power amplification circuitry. The speaker component inherently provides both sound generation and sound detection capabilities, reducing overall system power requirements
2Reliability
If capacitive microphones are used for high-volume sound recording, then audio performance can be improved, but amplifier circuitry and bias electronics draw significant power and increase cost
Solution Approach 1:
The piezoelectric speaker functions as both a speaker and a microphone capable of handling high-volume sounds. The piezoelectric material in the speaker diaphragm can detect sound pressure variations directly, including high-volume sounds, without requiring separate amplifier circuitry or bias electronics, thus maintaining audio performance while reducing power consumption and component cost
Solution Approach 2:
The piezoelectric speaker can operate across different sound pressure levels and frequency ranges by utilizing the inherent properties of piezoelectric materials. The same component that outputs sound can detect sound across a wide dynamic range, eliminating the need for separate low-volume and high-volume microphone configurations
3Adaptability or versatility
If two capacitive microphones are included for low-volume and high-volume sound, then audio performance across different volumes is improved, but device cost increases
Solution Approach 1:
The piezoelectric speaker serves as a universal sound detection device that can handle both low-volume and high-volume sounds, replacing the need for two separate capacitive microphones. This single component solution maintains adaptability across different sound levels while reducing component count and device cost
Solution Approach 2:
The patent merges the speaker and microphone functions into a single piezoelectric component. By combining the sound generation and sound detection capabilities in one piezoelectric speaker assembly, the system eliminates the need for separate microphone components, thereby reducing device cost while maintaining versatility
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 improves battery life and audio performance by dynamically selecting the best signal source for incident sound, extending the frequency range and reducing power consumption, while potentially lowering component costs.
Implementation Method 1
a piezoelectric speaker for generating sound
Implementation Method 2
receive a first signal from the piezoelectric speaker, the first signal induced at least in part by sound incident on the speaker
Data Source
AI summary
In accordance with embodiments of the present disclosure, a device may include a piezoelectric speaker for generating sound, a microphone, and a controller communicatively coupled to the speaker and the microphone. The controller may be configured to receive a first signal from the piezoelectric speaker, the first signal induced at least in part by sound incident on the speaker other than sound generated by the piezoelectric speaker, receive a second signal from the microphone, the second signal induced by sound incident on the microphone, process at least one of the first signal and the second signal to determine at least one characteristic of sound incident upon at least one of the piezoelectric speaker and the microphone, and select at least one of the microphone and the piezoelectric speaker as a signal source for incident sound based on the at least one characteristic.