Rectangular Magnet Micro Converter for Hearing Aids
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Solution Overview
Problem
Miniature electro-acoustic converters face challenges in achieving high acoustic output power and sound quality due to limited surface area and inefficient conversion efficiency, particularly in devices worn in the ear, where miniaturization restricts the size of components and increases power consumption.
Innovation Solution
The design features a magnet body within an elongate, rectangular contour with a magnetically conductive wall extending along a second contour, allowing a larger magnet body and efficient magnetic field utilization, combined with a membrane extending parallel to the main plane and a hollow sound chamber for optimal space utilization, resulting in a compact device with high conversion efficiency and natural sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the surface area of the active membrane is increased to improve acoustic output power, then the acoustic output power is improved, but the device dimensions increase making it unsuitable for miniature applications
Solution Approach 1:
The patent transitions from a conventional circular magnet arrangement to an elongated rectangular magnet body oriented transversely to the membrane plane. This dimensional change allows the magnetic field to be generated over a larger effective area without increasing the frontal footprint of the device, thereby achieving higher acoustic output power while maintaining compact dimensions suitable for earwear applications
2Loss of energy
If the magnet body size is increased to improve conversion efficiency, then the conversion efficiency is improved, but the device volume increases
Solution Approach 1:
The magnet body is elongated in the transverse direction (perpendicular to the membrane plane) rather than expanding in the frontal direction. This allows a larger magnet volume for improved conversion efficiency while maintaining a compact frontal profile that fits within the limited space of earwear devices
Solution Approach 2:
The magnet body is designed with an asymmetric elongated rectangular shape rather than a symmetric circular or cubic form. This asymmetric geometry optimizes the magnetic field distribution across the coil gap, improving conversion efficiency while minimizing the overall device volume by directing the magnet's bulk in the transverse dimension rather than uniformly in all directions
3Power
If a balanced armature converter is used to achieve high acoustic output power in a narrow frequency range, then the acoustic output power is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the complex balanced armature mechanism (including the suspended armature element and two magnetic poles) and replaces it with a simpler moving coil configuration. This extraction of the problematic component simplifies the device structure, reduces manufacturing complexity, and lowers costs while maintaining the capability to deliver high acoustic output power through the optimized magnet and coil arrangement
4Force
If the coil gap area is increased to improve magnetic field strength, then the magnetic field strength is improved, but the device surface area increases
Solution Approach 1:
Instead of increasing the coil gap area in the frontal plane, the patent extends the magnet body and coil winding in the transverse dimension. This creates an elongated coil gap that is wider in the transverse direction but maintains a compact frontal footprint, thereby achieving stronger magnetic field strength without increasing the device's surface area as seen from the front
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 configuration achieves unprecedented conversion efficiency and natural sound quality with a compact device, maintaining sufficient acoustic output power and clarity across a wide frequency range while minimizing device dimensions for comfortable wear.
Implementation Method 1
A rapidly changing electronic audio input signal is sent through the coils, whereby the armature element suspended therebetween is set into vibration
Implementation Method 2
the device housing comprises magnet means which maintain a magnetic field in the coil gap, the magnet means comprising a permanently magnetic magnet body
Implementation Method 3
the membrane assembly comprising an acoustic membrane and a coil element connected thereto... the membrane thus set into vibration in turn produces sound which is representative of the supplied audio signal
Data Source
AI summary
An electro-acoustic micro-converter can be applied in an audio device, and in particular in a hearing aid. The micro-converter is at least substantially block-shaped and includes an at least substantially rectangular acoustic membrane tensioned therein transversely of a longitudinal direction. A coil element is carried by the membrane and extends in a magnetic field maintained by magnet elements, including a permanently magnetic magnet body, in a coil gap around the magnet body.