Planar Dynamic Transducer with Segmented Magnet Plate
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Solution Overview
Problem
Conventional planar dynamic transducers face challenges in achieving optimal sound pressure and reduced acoustic damping due to the interaction of conductor mass, magnet mass, and magnetic flux density, leading to unwanted vibration modes and harmonic distortions, particularly in configurations with parallel magnet and conductor geometries.
Innovation Solution
A planar dynamic transducer design featuring a one-sided multipole magnetized magnet plate with elongate air gaps and magnet limbs, where the coil is positioned transversely relative to the air gaps and magnet limbs, allowing independent adjustment of drive power and acoustic load, and enabling improved sound transmissibility and reduced magnetic stray losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the conductor length and cross-section are increased to increase drive power and sound pressure, then the sound pressure is improved, but the conductor mass increases causing increased mass damping and reduced high-frequency response
Solution Approach 1:
The magnet arrangement is segmented into multiple magnet limbs with elongate air gaps, creating multiple magnetic zones. The coil is correspondingly divided into multiple conductor track bundles that can be independently optimized. This segmentation allows the total conductor length to be distributed across multiple zones, achieving high drive power without requiring excessive conductor mass in a single location.
Solution Approach 2:
The invention transitions from a conventional two-dimensional magnet arrangement to a three-dimensional structure with elongate air gaps extending in the longitudinal direction. This adds a temporal dimension to the magnetic field interaction, allowing the coil to traverse multiple magnetic zones over time, effectively increasing the active conductor length without proportionally increasing mass damping at any single location.
2Weight of stationary object
If the magnet mass is reduced to decrease thickness and weight, then the transducer becomes more compact, but the magnetic flux density decreases reducing drive power and sound pressure
Solution Approach 1:
The magnet plate features localized magnet limbs with concentrated magnetic flux density in specific zones rather than uniform distribution. The elongate air gaps create regions of high magnetic flux density where the coil interacts with the magnetic field, while other regions can have reduced magnet mass. This local quality optimization maintains high drive power where needed while reducing overall magnet mass.
Solution Approach 2:
Multiple magnet limbs are merged into a single magnet plate structure, creating a unified magnetic circuit that efficiently channels magnetic flux through the elongate air gaps. This merging allows the magnetic flux to be concentrated and reused across multiple zones, achieving high drive power with reduced total magnet mass compared to separate magnet assemblies.
3Ease of manufacture
If parallel magnet and conductor geometries are used to simplify design, then manufacturing is easier, but unwanted vibration modes and harmonic distortions occur due to interaction of conductor mass, magnet mass, and magnetic flux density
Solution Approach 1:
The invention introduces dynamic characteristics through the elongate air gaps and multiple magnet limbs, allowing the magnetic field configuration to vary along the longitudinal direction. This dynamic field distribution creates a more complex interaction pattern between the coil and magnetic field that suppresses unwanted vibration modes and harmonic distortions, while the overall design remains manufacturable through standardized components.
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 enhances sound quality by decoupling drive power from acoustic load, reducing unwanted vibration modes, and achieving more uniform diaphragm deflection, resulting in improved sound emission and signal quality.
Implementation Method 1
a force is exerted on a cylindrical coil which is fixed to a diaphragm and through which current flows, in the magnetic field of a round permanent magnet
Data Source
AI summary
Known planar dynamic sound transducers include a flat, multipole magnet arrangement having parallel magnet bars which are arranged with intermediate spaces and which have a uniform magnetization in the direction of one of the short dimensions. The magnet bars are parallel to the conductors of a coil that are applied to a diaphragm and on their side towards the diaphragm include precisely one kind of magnetic poles. The current planar dynamic sound transducer includes a magnet plate with elongate air gaps extending transversely relative to the conductor. The magnet plate is one-sided multipole magnetized so that on the side towards the diaphragm and the conductor it includes at least one North pole and one South pole respectively at both sides along each air gap. The width of the air gaps in the magnet plate can be freely selected because it does not depend on the width of the conductor tracks.