Miniature Speaker Magnetic Conduction Membrane Non-Linear Distortion
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Solution Overview
Problem
Miniature speakers in mobile devices suffer from non-linear distortion due to non-linear magnetic fields, which affects the quality of sound produced, especially in compact designs where size constraints limit optimal magnetic circuit configurations.
Innovation Solution
A miniature speaker design featuring a closed magnetic loop with a magnetic conduction membrane and a driving coil positioned by a pole plate, maintaining constant magnetic field lines during vibration to reduce distortion, and utilizing an elastic frame to suspend the membrane without contact with other components, with optional sealing using lubricating oil or magnetic fluid for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional magnetic circuit configuration is used in a compact speaker design, then the speaker size can be reduced, but non-linear distortion increases due to non-linear magnetic fields
Solution Approach 1:
The patent changes the magnetic field distribution parameters by introducing a magnetic conduction membrane with specific magnetic permeability between the magnet and voice coil. This modifies the magnetic circuit parameters to create a more uniform magnetic field in the gap, reducing non-linear distortion while maintaining compact dimensions. The magnetic conduction membrane's material properties and geometric parameters are optimized to achieve linear magnetic field distribution.
Solution Approach 2:
The magnetic conduction membrane acts as an intermediary component between the magnet and voice coil. It mediates the magnetic field distribution by conducting and redistributing magnetic flux, transforming the inherently non-linear magnetic field from a compact magnet into a more linear field across the voice coil gap, thereby reducing distortion without increasing speaker size.
2Power
If the magnetic field is strengthened to improve sound quality, then acoustic performance improves, but non-linear distortion increases due to field non-linearity
Solution Approach 1:
The patent optimizes magnetic field parameters by using a magnetic conduction membrane with specific thickness and magnetic permeability. This allows the system to achieve stronger overall magnetic field intensity for better acoustic output while simultaneously improving field uniformity to reduce non-linear distortion. The parameter optimization balances field strength and linearity.
Solution Approach 2:
The magnetic conduction membrane creates local variations in magnetic permeability and flux density distribution. By strategically positioning and dimensioning the membrane, the patent achieves localized magnetic field enhancement where needed for acoustic power while maintaining field linearity in the voice coil gap region, thus improving sound quality without increasing distortion.
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 significantly reduces non-linear distortion, enhancing acoustic performance and maintaining consistent magnetic field lines through the driving coil, thereby improving sound quality in compact speaker systems.
Implementation Method 1
the magnet 12, the magnetic conduction member 11, the magnetic conduction membrane 13 and the yoke 10 cooperatively form a closed magnetic loop... the magnetic field lines through the driving coil 131 will not change because the driving coil 131 is positioned by the pole plate 130
Implementation Method 2
a driving coil 131 positioned by the pole plate 130... the driving coil 131 at least partially overlaps the pole plate 130... for driving the magnetic conduction membrane 13 to vibrate
Implementation Method 3
an elastic frame 14 for suspending the magnetic conduction membrane 13 in a gap formed by the yoke side 100 and the magnetic conduction member 11
Implementation Method 4
For obtaining better acoustic performance, intervals between the magnetic conduction membrane 13 and the magnetic conduction member 11, and between the magnetic conduction membrane 13 and the yoke 10 may be sealed by lubricating oil, magnetic fluid, or conventional suspensions
Data Source
AI summary
A miniature speaker includes a frame having a sidewall including a first upper thinner portion and a first lower thicker portion, a magnetic circuit unit, a voice coil having a lead wire, and a diaphragm driven by the voice coil. The magnetic circuit unit has a yoke, a magnet mounted on the yoke, a pole plate attached to the magnet, and a magnetic gap. The yoke further includes a lower plate and a side extending from the lower plate, the side including a second thinner portion and a second lower thicker portion. A recess is accordingly formed by the thinner portions and the thicker portions for accommodating the lead wire of the voice coil. The recess defines a bottom formed by the thicker portions and an opening formed by the thinner portions thereby providing an enlarged space to the lead wire.