Concentric Loudspeaker Magnet Assembly for Low-Profile Audio
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Solution Overview
Problem
Smaller loudspeakers face challenges in achieving low frequency response due to limited diaphragm size and stiffer suspension, which restricts excursion and vibrational motion, and they often suffer from spurious vibrations that degrade high-frequency performance, making them unsuitable for low-profile devices like laptops and tablets.
Innovation Solution
A low-profile loudspeaker magnet assembly design featuring concentrically arranged annular and circular magnets with air gaps to accommodate a voice coil, along with a surround suspension system that minimizes spurious vibrations and enhances excursion, allowing for improved low-frequency response and reduced thickness for compact applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the loudspeaker size is reduced for low-profile devices, then the thickness is reduced, but the low-frequency response deteriorates due to limited diaphragm size and stiffer suspension
Solution Approach 1:
The magnet assembly is segmented into multiple components: a first magnet assembly with annular and circular magnets, a top plate, a second magnet assembly, and a bottom plate. This segmentation allows for a compact vertical arrangement that reduces overall thickness while maintaining the magnetic circuit integrity necessary for low-frequency response
Solution Approach 2:
The circular magnet is positioned concentrically within the annular magnet, creating a nested configuration. This nesting allows both magnet types to occupy the same radial space, reducing the overall footprint and enabling a more compact low-profile design without sacrificing magnetic field strength for low-frequency performance
2Area of moving object
If the diaphragm size is reduced for compact loudspeakers, then the overall size is reduced, but the excursion and vibrational motion are restricted, degrading low-frequency performance
Solution Approach 1:
The suspension system is designed with optimized compliance characteristics that allow the voice coil and diaphragm assembly to achieve greater excursion relative to its size. The magnetic assembly geometry and pole piece configuration create a magnetic field distribution that maintains force efficiency over a larger range of motion, enabling compact drivers to achieve adequate bass response
3Strength
If the suspension stiffness is increased in smaller loudspeakers, then the structural integrity is improved, but spurious vibrations increase that degrade high-frequency performance
Solution Approach 1:
Different portions of the suspension system are designed with different stiffness characteristics. The surround and spider are configured to provide appropriate local compliance that minimizes spurious vibrations while maintaining overall structural integrity. The magnetic assembly geometry is optimized to create a magnetic field that provides damping forces that suppress unwanted vibrations in the high-frequency range
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 design enhances low-frequency response and reduces spurious vibrations, enabling the loudspeaker to be suitable for low-profile devices such as laptops and tablets while maintaining high-frequency performance.
Implementation Method 1
Loudspeaker transducers utilize a combination of mechanical and electrical components to convert electrical signals (representative of the sound) into mechanical energy that produces sound waves
Implementation Method 2
Attached to the rear end of the diaphragm 102 is a coil of wire (known as the voice coil 114) that is wound around a cylindrical extension of the diaphragm 102
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A loudspeaker magnet assembly for a loudspeaker transducer (800) having a voice coil is provided that has a low profile construction. The loudspeaker magnet assembly may include: a first magnet assembly (804); top plate position below the first magnet assembly (804); second magnet assembly (806) positioned below the top plate; and bottom plate positioned below the second magnet assembly (806). The first magnet assembly (804) may include an annular outer magnet and a circular inner magnet. The top plate may include an annular outer top plate and a circular inner top plate and the second magnet assembly (806) may include an annular outer magnet and a circular inner magnet.