Microspeaker Edge-Tapped Venting for Wideband Ultrasonic Output
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Solution Overview
Problem
Microspeakers face limitations in generating a wide range of frequencies due to modal effects caused by sound waves with wavelengths similar to or smaller than their dimensions, particularly at ultrasonic frequencies, leading to a narrow band of efficient operation.
Innovation Solution
The microspeaker design includes an edge-tapped venting system where air is channeled from the diaphragm's periphery towards the center axis through a specific air path, utilizing a plate assembly with offset apertures and a central exit tube to steer pressure waves, enhancing frequency response and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If sound waves with wavelengths similar to or smaller than microspeaker dimensions are emitted, then ultrasonic frequencies can be generated, but modal effects occur in the chamber causing a lumpy response and limiting operation to a narrow band of frequencies
Solution Approach 1:
The patent introduces a third dimension by implementing a three-dimensional air path that channels air from the diaphragm periphery through the chamber toward the center axis and exits through a top-positioned tube. This spatial routing of air flow in multiple dimensions prevents modal effects and enables broad frequency response including ultrasonic frequencies (400 Hz to 50 kHz), resolving the contradiction between ultrasonic capability and frequency band width.
2Ease of manufacture
If a conventional venting port is positioned at the side of the microspeaker, then air can be vented from the chamber, but modal effects occur when sound wavelengths are approximately the same or smaller than microspeaker dimensions
Solution Approach 1:
The patent moves the air venting function from a conventional two-dimensional side port to a three-dimensional path that routes air from the diaphragm periphery through the chamber interior to a central exit tube positioned at the top. This spatial reconfiguration eliminates modal effects at ultrasonic frequencies while maintaining manufacturing feasibility, thereby expanding the frequency response range without sacrificing ease of manufacture.
3Device complexity
If air is vented directly from the chamber through a side port, then the structure is simple, but harmonic distortion increases and sound pressure levels decrease at ultrasonic frequencies
Solution Approach 1:
The patent implements a three-dimensional air path that channels air from the diaphragm periphery through the chamber toward the center axis and exits through a top-positioned tube. This spatial routing configuration reduces harmonic distortion and improves sound pressure levels at ultrasonic frequencies (400 Hz to 50 kHz) while maintaining reasonable structural complexity, resolving the contradiction between device complexity and performance reliability.
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 design achieves a broader frequency band of 400 Hz to 50 kHz with improved sound pressure levels and reduced harmonic distortion, enabling efficient operation across a larger frequency range.
Implementation Method 1
an actuator positioned within the space, the actuator including a diaphragm configured to oscillate in a first, axial direction
Implementation Method 2
The air, in the form of a pressure wave, can be channeled inwards, away from edges of the microspeaker and towards the center axis of the microspeaker through an air path
Data Source
AI summary
A microspeaker includes a frame defining a space; and an actuator positioned within the space, the actuator including a diaphragm configured to vibrate in a first direction during operation. A center axis of the diaphragm extends in the first direction. A plate assembly mechanically couples to the frame and defines a path for venting fluid from the space. The plate assembly includes: a first plate extending in a plane and defining first apertures that are offset from the center axis in the plane; and a second plate defining a second aperture intersected by the center axis. The second plate includes: an inner recessed region abutting the second aperture; and an outer non-recessed region. The first plate is mechanically coupled to the second plate, the first plate and the inner region of the second plate defining a channel that fluidly couples the first apertures to the second aperture.