Loudspeaker Vibration Control via Axial Shaker
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Solution Overview
Problem
Traditional loudspeakers induce unwanted vibrations on baffles due to their inertial mass, leading to spurious sounds, and there is a need for a system to control these vibrations, especially for low-frequency sound applications where increased vibrations are desired.
Innovation Solution
Integration of a shaker mechanism within the loudspeaker structure, comprising an external cylinder made of ferromagnetic material with control coils and elastic suspensions, which moves axially within the magnetic field to counteract or enhance baffle vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a traditional loudspeaker structure is used, then the loudspeaker can produce sound through membrane vibration, but unwanted vibrations are induced on the baffle due to inertial mass movement
Solution Approach 1:
The patent applies preliminary anti-action by introducing a control coil that generates a counteracting magnetic force before the unwanted vibrations fully develop. The control coil, positioned in the magnetic field of the magnetic assembly, receives control signals that generate forces opposing the inertial mass movement, thereby preemptively counteracting the harmful baffle vibrations while preserving the primary acoustic function
2Object-generated harmful factors
If the loudspeaker structure is modified to add vibration control components, then baffle vibrations can be controlled, but the device complexity increases
Solution Approach 1:
The patent merges the vibration control function with the existing loudspeaker structure by utilizing the magnetic assembly's field and incorporating the control coil into the basket assembly. This integration allows the control mechanism to be combined with structural components already present in the loudspeaker, adding vibration control capability while minimizing overall structural complexity
Solution Approach 2:
The magnetic assembly serves dual functions: generating the magnetic field for the voice coil operation and providing the magnetic field for the control coil's vibration control function. This multi-functionality reduces the need for separate control mechanisms, thereby limiting the increase in device complexity while achieving effective vibration control
3Object-generated harmful factors
If control coils are added to the magnetic assembly, then vibration control is achieved, but manufacturing cost increases
Solution Approach 1:
The control coil is integrated into the existing basket assembly structure, merging two functional elements (support structure and control mechanism) into a single integrated component. This reduces the total number of separate parts that need to be manufactured and assembled, thereby controlling manufacturing costs while achieving vibration control functionality
4Volume of moving object
If the loudspeaker is designed to be compact, then installation space is reduced, but adding vibration control systems may increase size
Solution Approach 1:
The control coil is nested within the existing magnetic assembly structure, specifically positioned in the air gap region between the magnetic assembly and the basket. This nesting approach allows the control mechanism to occupy space that already exists in the loudspeaker design, achieving vibration control without significantly increasing the overall loudspeaker volume
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 shaker system effectively reduces unwanted vibrations and enhances low-frequency vibrations, providing a compact, inexpensive solution for noise reduction and bass enhancement applications, while maintaining acoustic performance.
Implementation Method 1
When the voice coil (3), which is immersed in a radial magnetic field, is crossed by electrical current, according to the Lorentz law, a force is generated
Implementation Method 2
at least one elastic suspension (8, 8') connected to said external cylinder (7) and to said magnetic assembly (M) in such a way as to maintain said external cylinder (7) in coaxial position relative to said magnetic assembly
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A loudspeaker (1) with vibration control system comprises: a magnetic assembly (M) comprising an air gap (T), a voice coil (3) supported by a cylindrical support (30), a basket (4) connected to the magnetic assembly (M), a centering device (5) connected to the basket (4) and to the cylindrical support (6), a membrane (6) connected to the basket (4) and to the cylindrical support (30), an external cylinder (7) disposed around the magnetic assembly (M), at least one control coil (71, 72) supported by the external cylinder and directed towards the magnetic assembly, at least one elastic suspension (8, 8') connected to the external cylinder (7) to permit an axial movement of the external cylinder (7) with respect to the magnetic assembly (M).