Magnetic Distributed Mode Actuator Eliminates Lead in Loudspeakers
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Solution Overview
Problem
Conventional loudspeakers using piezoelectric materials often contain toxic chemicals like lead and have limitations in generating strong magnetic fields, leading to inefficient power transfer and brittle components, which affect audio response and device ruggedness.
Innovation Solution
The development of magnetic distributed mode actuators (DMAs) that utilize a magnetic circuit with a coil and permanent magnet, attached to an inertial beam, which excites vibrational modes in a panel to produce sound, eliminating lead and offering stronger magnetic fields and more efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If piezoelectric materials are used in conventional loudspeakers, then the device can produce sound, but it contains toxic chemicals like lead and has brittle components
Solution Approach 1:
The patent removes piezoelectric materials containing toxic chemicals like lead from the loudspeaker system. Instead, it uses a magnetic actuator system with a coil and permanent magnet that excites vibrational modes in the panel directly, eliminating the harmful piezoelectric components while maintaining sound production capability
Solution Approach 2:
The patent replaces the piezoelectric mechanical system with an electromagnetic system. A magnetic actuator uses electromagnetic fields to induce vibrational modes in the panel, substituting the piezoelectric effect with electromagnetic induction to achieve the same sound production function without toxic materials
2Use of energy by moving object
If piezoelectric actuators are used, then sound can be produced, but power transfer efficiency is limited
Solution Approach 1:
The magnetic actuator is designed to directly excite specific vibrational modes in the panel at their resonant frequencies. By coupling the actuator to the panel and tuning it to resonate at the panel's natural frequencies, the system achieves more efficient energy transfer and improved audio response compared to piezoelectric actuators
Solution Approach 2:
The patent optimizes the magnetic actuator parameters including coil turns, magnet strength, and coupling position to maximize power transfer efficiency. The actuator is tuned to operate at specific frequencies that match the panel's vibrational modes, improving energy utilization and audio output
3Reliability
If conventional loudspeaker designs are used, then audio output can be achieved, but the device lacks ruggedness
Solution Approach 1:
The panel serves multiple functions: it acts as both the structural element of the device and the sound-radiating surface. The magnetic actuator is integrated directly onto the panel, eliminating the need for separate fragile acoustic components and creating a more rugged, multi-functional design
Solution Approach 2:
The patent removes traditional loudspeaker components such as voice coils, magnets mounted on separate frames, and rigid acoustic chambers. By using the panel itself as the radiating surface and integrating the actuator directly, the design eliminates fragile parts while maintaining audio functionality
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 magnetic DMAs provide a smoother audio response across frequencies, are free from toxic chemicals, and exhibit a more rugged design compared to conventional piezoelectric DMAs, with improved power transfer efficiency and reduced brittleness.
Implementation Method 1
an interaction between a magnetic field of the magnet and a magnetic field from the electrically-conducting coil applies a force sufficient to displace the member in the direction perpendicular to the plane
Implementation Method 2
a magnetic circuit that features a coil and a permanent magnet coupled to an inertial beam
Implementation Method 3
Vibrational modes are excited in the inertial beam by energizing the coil of the magnetic circuit
Implementation Method 4
Vibrational modes are excited in the inertial beam by energizing the coil of the magnetic circuit
Data Source
AI summary
A distributed mode actuator (DMA) includes a flat panel extending in a plane and a rigid, elongate member extended parallel to the plane. The member is mechanically coupled to a face of the flat panel at a point. An end of the member is free to vibrate in a direction perpendicular to the plane. The DMA also includes a magnet and an electrically-conducting coil. Either the magnet or the coil is mechanically coupled to the member. When the coil is energized, an interaction between a magnetic field of the magnet and a magnetic field from the coil applies a force sufficient to displace the member in the direction perpendicular to the plane. The DMA further includes an electronic control module electrically coupled to the coil and programmed to energize the coil to vibrate the member to produce an audio response from the flat panel.