Electromagnetic Actuator With Opposed Magnet-Spring Force Balance
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Solution Overview
Problem
Existing electrodynamic actuators and output devices suffer from poor low-frequency performance due to mechanical constraints on the suspension between the inner and outer magnetic circuit parts, limiting resonance frequency and device lifetime.
Innovation Solution
The magnet force and spring force are opposed, allowing for a softer suspension without compromising the device's use and lifetime, achieved by reversing the magnet force to compensate or overcompensate the spring constant, thereby reducing the total force between the magnetic circuit parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a soft suspension is used between the inner and outer magnetic circuit parts to lower resonance frequency, then low frequency performance is improved, but the device lifetime and reliability deteriorate due to inability to withstand high forces during operation and drop tests
Solution Approach 1:
The patent applies the counterweight principle by introducing a magnet system that generates a magnet force opposing the spring force. The magnet system includes a first magnet and a second magnet arranged to create a magnetic field that exerts a force counteracting the suspension force, thereby allowing softer suspension while maintaining structural integrity under load.
Solution Approach 2:
The patent changes the force balance parameters by adjusting the magnet system configuration. The first and second magnets are positioned and sized to generate a magnet force that compensates for the spring constant, effectively changing the net force parameter in the system to allow lower resonance frequency without compromising reliability.
2Measurement precision
If the suspension is made softer to improve low frequency performance, then resonance frequency is lowered, but the ability to withstand forces during high frequency operation and drop tests is reduced
Solution Approach 1:
The magnet system acts as a counterweight mechanism where the magnet force specifically counteracts the spring force. This allows the suspension to be softer (lower resonance frequency) while the magnet force provides the necessary strength to withstand high frequency operation forces and drop test impacts.
Solution Approach 2:
The magnet system serves as an intermediary force that mediates between the spring force and the mechanical loads. It transfers and compensates for forces during operation, allowing the soft suspension to handle high frequency forces and drop test impacts without failing.
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 approach lowers the resonance frequency of the actuator and output device without limiting their use or lifetime, providing more design freedom for output power, sound quality, and desired lifetime.
Implementation Method 1
The coil arrangement comprises at least one voice coil, which has an electrical conductor in the shape of loops running around a coil axis in a loop section
Implementation Method 2
The magnet system is designed to generate a magnetic field transverse to the electrical conductor in the loop section
Implementation Method 3
the spring arrangement couples the inner magnetic circuit part to the outer magnetic circuit part and allows a relative movement between the inner magnetic circuit part and the outer magnetic circuit part in an excursion direction
Implementation Method 4
The magnet system comprises an (annular) outer magnetic circuit part, which runs radially out of the coil arrangement... the magnet system is designed to generate a magnetic field transverse to the electrical conductor
Implementation Method 5
causes a magnet force acting between the inner magnetic circuit part and the outer magnetic circuit part in a magnet force direction parallel to the coil axis
Data Source
AI summary
The invention relates to an electrodynamic actuator with a coil arrangement, a magnet system and a spring arrangement, wherein the magnet system comprises an outer magnetic circuit part, which runs radially out of the coil arrangement, wherein the coil arrangement and the outer magnetic circuit part are arranged in fixed relation to each other, and wherein the magnet system comprises an inner magnetic circuit part, which is arranged radially within the coil arrangement. The spring arrangement couples the inner magnetic circuit part to the outer magnetic circuit part and allows a relative movement between the inner magnetic circuit part and the outer magnetic circuit part in an excursion direction parallel to the coil axis, wherein the magnet force and the spring force are opposed. In addition, an output device is disclosed, which comprises a sound emanating structure and an electromagnetic actuator of said kind connected thereto.