Loudspeaker Inverted Drive Unit for Rocking and Ticking Control
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Solution Overview
Problem
Conventional loudspeakers face challenges with rocking instability due to the distribution of mass, require flexible lead wires that cause ticking noise, and are limited by the need for large, expensive magnets and enclosures, making them unsuitable for compact and cost-effective subwoofer applications.
Innovation Solution
A loudspeaker design featuring a stationary voice coil and a translatable magnet unit, with a center of gravity between suspension elements, reduces rocking and eliminates the need for flexible lead wires, allowing for a shallow, lightweight, and cost-effective subwoofer with improved heat dissipation and magnetic shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional loudspeaker design with a voice coil attached to the diaphragm is used, then the drive unit can effectively move the diaphragm to produce sound, but the flexible lead wires required cause ticking noise and the mass distribution causes rocking instability
Solution Approach 1:
The patent inverts the conventional loudspeaker drive unit configuration by making the magnet unit translatable (attached to the diaphragm) and the voice coil stationary (attached to the frame). This inversion eliminates the need for flexible lead wires connecting a moving voice coil to the frame, thereby removing the source of ticking noise. Simultaneously, the inverted configuration allows for optimized mass distribution with the center of gravity positioned between the suspension elements, eliminating rocking instability.
2Force
If large magnets are used in conventional loudspeakers to achieve sufficient magnetic field strength, then the magnetic field is strong enough for effective sound reproduction, but the loudspeaker becomes deep and expensive
Solution Approach 1:
By inverting the drive unit configuration and attaching the magnet unit to the diaphragm rather than the frame, the patent enables a shallower overall loudspeaker design. The translatable magnet unit can be positioned closer to the voice coil, reducing the required magnetic path length and overall depth. This configuration maintains sufficient magnetic field strength while reducing the size of large, expensive magnets needed in conventional designs.
Solution Approach 2:
The patent repositions the magnet unit from a frame-mounted stationary position to a diaphragm-mounted translatable position, effectively changing the spatial arrangement in the axial dimension. This dimensional reconfiguration allows the magnetic circuit to be more compact, reducing the depth requirement while maintaining the necessary magnetic field strength for effective sound reproduction.
3Stability of the object's composition
If a translatable magnet unit with center of gravity between suspension elements is used, then rocking is inhibited and stable operation is achieved, but the drive unit structure becomes different from conventional designs
Solution Approach 1:
The patent inverts the conventional drive unit configuration, making the magnet unit translatable and the voice coil stationary. This inversion naturally positions the center of gravity of the translatable part between the first and second landing surfaces of the suspension elements, which inhibits rocking modes. While the structure differs from conventional designs, the inverted configuration actually simplifies certain aspects by eliminating flexible lead wires and enabling more straightforward mass distribution for stability.
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 achieves stable low-frequency sound reproduction with reduced depth, efficient heat transfer, and cost-effective manufacturing, enabling compact subwoofer applications without rocking instability and ticking noise.
Implementation Method 1
By energising the voice coil, the magnet unit and the voice coil magnetically cooperate, i.e. magnetically interact, with each other to effect displacement of the combination of the voice coil and the diaphragm
Implementation Method 2
The translatable part of the drive unit includes a magnet unit configured to produce a magnetic field in an air gap
Implementation Method 3
The loudspeaker may include one or more suspension elements, preferably at least two suspension elements
Data Source
AI summary
There is provided a loudspeaker including a frame, a diaphragm suspended from the frame and a drive unit; wherein the drive unit has a stationary part secured to the frame and a translatable part secured to the diaphragm, the translatable part of the drive unit includes a magnet unit configured to produce a magnetic field in an air gap, the stationary part of the drive unit includes a voice coil configured to sit in the air gap when the diaphragm is at rest; and the loudspeaker is operable to energise the voice coil to cause the magnet unit to move along a movement axis relative to the voice coil, thereby moving the diaphragm along the movement axis to produce sound.