MEMS Audio Speaker with Shutter Element for Low-Frequency Sound
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Solution Overview
Problem
Conventional loudspeaker design is inefficient for producing low-frequency sounds, requiring larger and more powerful speakers, which limits their compactness and energy efficiency, especially for applications like mobile devices.
Innovation Solution
A MEMS-based audio speaker system utilizing a planar oscillation element and a shutter element to generate ultrasonic acoustic signals, which are modulated to produce audible audio signals across a wide frequency range, including sub-100 Hz, through amplitude modulation by alternately obscuring and revealing an aperture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional speaker design is used for low-frequency sounds, then sound quality is improved, but device size increases and energy consumption increases
Solution Approach 1:
The patent replaces the traditional mechanical speaker cone system with a MEMS-based electrostatic transducer system. The movable electrode and fixed electrode create an electrostatic field that drives a diaphragm, eliminating the need for large mechanical components while achieving equivalent acoustic output. This substitution of mechanical systems with electrostatic fields enables compact low-frequency speaker design.
Solution Approach 2:
The patent changes the operating parameters by using electrostatic actuation instead of traditional electromagnetic or mechanical drive mechanisms. By controlling the voltage applied to the movable electrode, the system can generate low-frequency sounds without requiring large physical dimensions, thus resolving the contradiction between sound quality and device size.
2Reliability
If traditional speaker design is used for low-frequency sounds, then sound quality is improved, but energy consumption increases
Solution Approach 1:
The electrostatic MEMS transducer system replaces energy-intensive mechanical speaker systems. The electrostatic field generation requires significantly less power compared to traditional electromagnetic voice coils and mechanical drivers, enabling low-frequency sound production with reduced energy consumption while maintaining sound quality.
Solution Approach 2:
By changing the actuation mechanism to electrostatic control with variable voltage application, the system achieves efficient energy utilization. The electrostatic field can be precisely controlled to match the acoustic output requirements, avoiding the continuous high power consumption of traditional low-frequency speakers.
3Device complexity
If traditional speaker design is used, then simplicity of structure is maintained, but adaptability to different frequency ranges is limited
Solution Approach 1:
The MEMS electrostatic transducer serves multiple functions within a single compact structure. The same basic device can produce sounds across a wide frequency range by varying the drive signal characteristics, eliminating the need for separate tweeters, mid-range drivers, and woofers required in traditional multi-component speaker systems.
Solution Approach 2:
The system employs dynamic control of the electrostatic field through variable voltage application to the movable electrode. By dynamically adjusting the electrical parameters, the transducer can adapt to different frequency ranges and acoustic requirements, providing versatility while maintaining structural simplicity.
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 generation of high-fidelity audio signals across the audible frequency spectrum in a compact, energy-efficient manner, suitable for mobile devices and applications where size and sound quality are crucial.
Implementation Method 1
The planar oscillation element may be configured to generate an ultrasonic acoustic signal in a direction orthogonal to a surface of the planar oscillation element
Implementation Method 2
The shutter element may be configured to obscure the aperture to modulate the ultrasonic acoustic signal such that an audio signal is generated
Data Source
AI summary
Techniques described herein generally include methods and systems related to a MEMS-based audio speaker system configured for generating an audio signal. The speaker system includes one or more apertures in the speaker system positioned to receive the ultrasonic carrier signal and one or more movable and over-sized obstruction elements that are configured to modulate the ultrasonic carrier signal and thereby generate an audio signal. Because the movable obstruction elements are configured to overlap one or more edges of the apertures when in the closed position, modulation depth of the generated audio signal can be substantially improved or otherwise varied.