Speaker Device With Through-Hole Bobbin for Magnetic Fluid Control
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Solution Overview
Problem
Existing speaker devices with magnetic fluid-filled gaps face issues such as magnetic fluid scattering due to uneven voice coil cross-sectional shapes, leading to reduced fluid amounts and unstable signal reproduction, and fluid separation by the coil bobbin, affecting centering accuracy and acoustic conversion efficiency.
Innovation Solution
A speaker design featuring a main magnetic gap and a sub-magnetic gap filled with magnetic fluid, where the sub-magnetic gap has through-holes and a support ring to maintain fluid flow and high magnetic flux density, and a magnetic gradient is formed to prevent fluid scattering, ensuring stable signal reproduction and improved acoustic conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the main magnetic gap is filled with magnetic fluid to support the voice coil, then the damper weight is reduced and acoustic conversion efficiency is improved, but the magnetic fluid scatters due to agitation from uneven voice coil cross-sectional shape, reducing stable signal reproduction
Solution Approach 1:
The magnetic gap is divided into a main magnetic gap (where the voice coil is located) and a sub-magnetic gap (filled with magnetic fluid). This segmentation allows the voice coil to operate in the main gap while the sub-gap provides stable magnetic fluid support, preventing scattering and ensuring reliable signal reproduction.
Solution Approach 2:
The sub-magnetic gap filled with magnetic fluid acts as an intermediary between the voice coil and the external environment. It provides a stable magnetic field region that supports the voice coil without direct contact, preventing fluid scattering while maintaining acoustic conversion efficiency.
2Measurement precision
If a sub-magnetic gap filled with magnetic fluid is added to improve centering accuracy, then fluidity is maintained, but the magnetic fluid is separated into internal and external parts by the coil bobbin, hindering fluidity and reducing centering accuracy
Solution Approach 1:
The coil bobbin is designed with through-holes that allow magnetic fluid to pass through. This porous structure enables the magnetic fluid to flow continuously between the internal and external regions of the sub-magnetic gap, maintaining fluidity and centering accuracy without separation.
3Strength
If the coil bobbin is made solid to provide structural support, then mechanical strength is improved, but the magnetic fluid flow is blocked, reducing centering accuracy and signal reproduction stability
Solution Approach 1:
The coil bobbin incorporates through-holes that maintain its structural strength while allowing magnetic fluid to flow through. This porous design enables the bobbin to provide mechanical support to the voice coil while ensuring continuous magnetic fluid circulation for stable signal reproduction.
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 effectively prevents magnetic fluid scattering, maintains stable centering of the coil bobbin, and enhances acoustic conversion efficiency by ensuring continuous fluid flow and high magnetic flux density, resulting in improved signal reproduction and sound quality.
Implementation Method 1
a magnetic fluid filling at least one sub-magnetic gap formed between the sub-plate and the yoke
Implementation Method 2
when the voice coil is energized, the coil bobbin changes (moves) in an axial direction of the center pole portion
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Acoustic conversion efficiency is improved and a stable signal reproduction operation is ensured. Provided is a speaker device including: a magnet having a central axis; a yoke having a central axis, the central axis of the yoke being identical to the central axis of the magnet, the magnet being attached to the yoke; a main plate attached to the magnet; at least one sub-plate attached to the magnet and positioned to be separated from the main plate in an axial direction of the central axis; a coil bobbin formed in a tubular shape and changeable in the axial direction; a voice coil wound around an outer circumferential surface of the coil bobbin, at least a portion of the voice coil being disposed in a main magnetic gap formed between the main plate and the yoke; a vibration plate having an inner circumferential portion connected to the coil bobbin, and vibrating according to a change of the coil bobbin; and a magnetic fluid filling at least one sub-magnetic gap formed between the sub-plate and the yoke, wherein a through-hole positioned in the sub-magnetic gap filled with the magnetic fluid is formed in the coil bobbin.