Speaker Unit Magnetic Fluid Damping Resonance Sharpness
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Solution Overview
Problem
Current speaker units driven by voltage face issues with linearity in driving force and sound quality due to high-frequency output limitations and oscillations near the minimum resonance frequency, which are not adequately addressed by existing solutions such as magnetic fluid injection, as they require additional parts and increased manufacturing costs without sufficient viscosity-dependent effectiveness.
Innovation Solution
A speaker unit with a magnetic fluid containing oxide iron in a synthetic ester is used, eliminating the need for a damper and adjusting the mechanical resonance sharpness to between 0.5 and 0.6, ensuring reduced oscillations at the minimum resonance frequency and improved sound quality without increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a resistance-adding seat such as a non-woven sheet is attached to the back pressure to reduce oscillations, then oscillations at the frequency near the minimum resonance frequency are reduced, but the number of parts is increased, causing deterioration of outer appearance, increased manufacturing cost, and additional working process
Solution Approach 1:
The patent merges the oscillation reduction function with the existing magnetic gap structure by injecting magnetic fluid directly into the gap. This eliminates the need for separate resistance-adding seats or dampers, as the magnetic fluid provides the necessary damping effect through its viscosity while being integrated into the existing magnetic circuit components (magnet and yoke).
Solution Approach 2:
The patent uses magnetic fluid (a liquid or semi-liquid material) injected into the magnetic gap to provide viscous damping. The magnetic fluid acts as a hydraulic/pneumatic damping medium that dissipates oscillation energy through its viscosity, replacing the need for mechanical resistance-adding seats while providing smooth, continuous damping control.
2Object-affected harmful factors
If magnetic fluid is injected into the magnetic gap to reduce oscillations, then oscillations are reduced to some extent, but a sufficient effect cannot be exhibited depending on the viscosity value of the magnetic fluid, elasticity of damper, edge, and weight of cone
Solution Approach 1:
The patent specifies precise parameter ranges for the magnetic fluid viscosity (0.01 to 0.1 Pa·s) and mechanical resonance sharpness (0.45 to 0.55) to optimize oscillation reduction. By controlling these parameters within specific ranges, the invention achieves reliable and sufficient damping effect without depending on variable factors like damper elasticity or cone weight, thereby improving manufacturing precision and consistency.
3Reliability
If the sheet is separated, then the function of reducing oscillations is deteriorated, but the sheet increases manufacturing cost and requires additional attachment process
Solution Approach 1:
The magnetic fluid is injected into the magnetic gap during the manufacturing process and remains permanently in place, providing continuous oscillation reduction without requiring separate attachment or assembly steps. The magnetic fluid serves the dual purpose of maintaining magnetic flux and providing damping, eliminating the need for separate resistance-adding components that would require attachment processes and could become separated.
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 solution effectively reduces oscillations at the minimum resonance frequency, enhancing sound quality and maintaining a good output state for the low-frequency band, while keeping manufacturing costs low by using a magnetic fluid with high viscosity and oxide iron in a synthetic ester, which adjusts the mechanical resonance sharpness appropriately.
Implementation Method 1
a magnetic fluid having a viscosity that provides a suitable brake is injected into a magnetic gap
Implementation Method 2
a magnetic brake due to power generation of the coil is cancelled
Implementation Method 3
lowering a mechanical resonance sharpness and reducing oscillations at a frequency near a minimum resonance frequency
Data Source
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AI summary
[Object] To lower a mechanical resonance sharpness and reduce oscillations near a minimum resonance frequency, to thereby improve the sound quality. [Solving Means] A speaker unit includes: a magnet that generates a magnetic force; a magnetic gap that causes the magnetic force to act; a yoke that is provided to be partially opposed to the magnet and forms a magnetic circuit that guides the magnetic force of the magnet to the magnetic gap; a coil bobbin that is formed in a tubular shape and is set to be axially vibratable with respect to the magnet and the yoke; a coil that is wound around the coil bobbin and partially placed in the magnetic gap; a cone that is vibrated in accordance with vibration of the coil bobbin; an edge that retains the cone at almost a center; and a frame that fixes each of the edge and the yoke, in which into the magnetic gap a magnetic fluid is injected, the magnetic fluid is set to have a viscosity equal to or larger than a predetermined value and a mechanical resonance sharpness is set to be equal to or smaller than 1.0, and sound proportional to a current is output by current drive.