Concentric Magnet Electromagnetic Actuator for Compact Panel Audio
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Solution Overview
Problem
Conventional loudspeakers face challenges in creating a compact panel audio loudspeaker that can produce sufficient force over a prescribed audio bandwidth while fitting within a small physical space, effectively exciting vibrational modes in a diaphragm.
Innovation Solution
The use of concentric axially and radially magnetized magnets in electromagnetic actuators, which maximize and balance the flux density at both inner and outer faces of the magnetic air gap, allowing for increased force output in a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional electromagnetic actuators are used in panel audio loudspeakers, then the device can produce sound, but the actuator occupies excessive space and cannot generate sufficient force output within compact dimensions
Solution Approach 1:
The magnetic circuit is segmented into multiple independent magnet assemblies, each with its own voice coil. This allows the total force output to be distributed across multiple smaller magnetic gaps, increasing the force density within a compact volume while maintaining manageable dimensions for each individual magnet assembly.
Solution Approach 2:
Multiple magnet assemblies are arranged in a nested configuration where smaller magnets are positioned within or adjacent to larger ones. This nesting strategy maximizes the use of available space, allowing multiple magnetic circuits to occupy a minimized overall volume while each contributes to the total force output.
2Volume of moving object
If the actuator is designed to fit within limited physical space, then the device becomes compact, but the flux density becomes insufficient to excite vibrational modes effectively
Solution Approach 1:
The magnetic circuit design concentrates magnetic flux density in specific localized regions where it is most needed for effective diaphragm excitation. By optimizing the magnetic path and gap dimensions locally, high flux density is achieved in critical areas while the overall actuator volume remains compact.
Solution Approach 2:
The patent transitions from a single-plane magnetic circuit to a three-dimensional arrangement of multiple magnet assemblies stacked or arranged in layers. This dimensional expansion allows increased total magnetic flux and force output within a compact footprint by utilizing vertical or radial space efficiently.
3Force
If multiple magnet assemblies are used to increase force output, then the actuator can generate sufficient force, but the device complexity increases
Solution Approach 1:
Multiple magnet assemblies and voice coils are electrically connected in series or parallel configurations, merging them into a single integrated electromagnetic system. This merging approach allows the actuator to achieve high force output through combined operation while presenting a unified, manageable structure with reduced overall complexity compared to independently controlled assemblies.
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 configuration enables the development of compact electromagnetic actuators with high force output, suitable for integration into mobile devices, capable of generating both acoustic and haptic feedback within limited physical constraints.
Implementation Method 1
The vibration system comprises a diaphragm, a voice coil and a magnetic circuit system. The magnetic circuit system comprises an outer magnet, an inner magnet, a yoke and a pole piece
Implementation Method 2
electromagnetic actuators, which maximize and balance the flux density at both inner and outer faces of the magnetic air gap, allowing for increased force output
Implementation Method 3
concentric axially and radially magnetized magnets in electromagnetic actuators, which maximize and balance the flux density at both inner and outer faces of the magnetic air gap
Implementation Method 4
The inner magnet is magnetized axially and the outer magnet is magnetized radially
Implementation Method 5
operating by inducing uniformly distributed vibration modes in a panel through an electro-acoustic actuator
Implementation Method 6
capable of generating both acoustic and haptic feedback within limited physical constraints
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C
AI summary
An electromagnetic actuator includes an inner magnet arranged relative to an axis, an outer magnet arranged a radial distance from the axis, an inner radial wall of the outer magnet facing an outer radial wall of the inner magnet, the inner and outer radial walls being separated by an air gap, a voice coil arranged in the air gap separating the inner and outer magnets, and an actuator coupling plate attached to the voice coil. During operation of the device electrical activation of the voice coil causes axial motion of the actuator coupling plate.