Multi-Resonance MEMS Speaker Diaphragm for Wide Frequency Output
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Solution Overview
Problem
Conventional voice coil motors in micro speakers, such as those used in earphones, are limited in producing sufficient sound pressure across both high-frequency and low-frequency ranges, are complex to manufacture, difficult to miniaturize, and experience excessive power consumption due to multiple energy transformations during operation.
Innovation Solution
A microelectromechanical apparatus with multiple vibrating portions, comprising a base and a thin film with stationary, peripheral, and central parts, and first and second elastic parts with piezoelectric material layers, which vibrates differently in response to low-frequency and high-frequency electrical signals to achieve balanced sound pressure across frequency ranges while minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single voice coil motor is used to produce sound, then the structure is simple, but it cannot produce sufficient sound pressure across both high-frequency and low-frequency ranges
Solution Approach 1:
The thin film is divided into multiple vibrating portions (first vibrating portion and second vibrating portion) with different resonance frequencies. The first vibrating portion resonates at a first resonance frequency while the second vibrating portion resonates at a second resonance frequency higher than the first. This segmentation allows the single motor to drive multiple resonant modes, expanding the usable frequency range without adding multiple motors.
Solution Approach 2:
Different portions of the thin film are designed with different mechanical properties to achieve different resonance frequencies. The first vibrating portion and second vibrating portion have different local qualities (mass distribution, stiffness, geometry) that enable them to resonate at different frequencies when driven by the same voice coil motor, allowing broad frequency coverage from a single actuator.
2Volume of moving object
If a typical voice coil motor is used, then it can produce sound, but it involves a complex manufacturing process and is difficult to reduce in size
Solution Approach 1:
The voice coil motor is integrated directly with the thin film structure, merging the motor components with the vibrating element. This integration eliminates the need for separate motor housing and mounting structures, reducing overall size and simplifying the manufacturing process. The thin film itself serves as both the vibrating element and the motor component interface.
Solution Approach 2:
The use of a thin film as the vibrating structure allows for miniaturization while maintaining acoustic performance. The thin film can be manufactured using flexible manufacturing processes such as thin-film deposition and micromachining techniques, which are more scalable and simpler than traditional motor assembly processes.
3Use of energy by moving object
If a voice coil motor undergoes multiple energy transformations during operation, then it can drive the vibrating elements, but it results in excessive power consumption
Solution Approach 1:
The system is designed to operate at the resonance frequencies of the thin film's vibrating portions. By driving the first vibrating portion at its first resonance frequency and the second vibrating portion at its second resonance frequency, the system maximizes acoustic output for minimal input power. Resonant operation reduces the power required to achieve sufficient sound pressure levels.
Solution Approach 2:
The system changes operating parameters (driving frequency) to match the resonance frequencies of different vibrating portions. By switching between driving at the first resonance frequency and the second resonance frequency, the system optimizes energy efficiency across different frequency ranges, reducing overall power consumption while maintaining driving capability.
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 apparatus effectively produces sound pressure across a wide frequency range with reduced power consumption by varying the stiffness and resonance frequencies of its vibrating parts, addressing the limitations of conventional voice coil motors.
Implementation Method 1
The first elastic part includes at least one first piezoelectric material layer... When a low frequency electrical driving signal is input to the first electrode, the peripheral part vibrates... When a high-frequency electrical driving signal is input to the second electrode, the peripheral part vibrates...
Data Source
AI summary
A microelectromechanical apparatus includes a base and a thin film including a stationary part disposed on the base, a peripheral part, a central part surrounded by the peripheral part, and a first and second elastic part. The first elastic part is connected to the stationary part and the peripheral part. The second elastic part is connected to the peripheral part and the central part. When low frequency signal is input to a first electrode of the first elastic part, the peripheral part and the and the central part respectively vibrate with a first and second low-frequency amplitudes. When high-frequency signal is input to a second electrode of the second elastic part, the peripheral part and the central part respectively vibrate with a first and second high-frequency amplitudes. A difference between the first and second low-frequency amplitudes is smaller than a difference between the first and second high-frequency amplitudes.