Loudspeaker Reluctance Force Compensation via Digital Signal Processing
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Solution Overview
Problem
Conventional loudspeakers suffer from audio distortion due to reluctance force, a nonlinear mechanical force caused by varying voice-coil inductance, which degrades sound quality and speech intelligibility, and existing solutions either increase costs or ignore the issue, leading to suboptimal audio output.
Innovation Solution
A method and system for nonlinear control of loudspeakers that determine a target displacement of the speaker driver's diaphragm based on a physical model and source signal, calculating a corrected drive signal to compensate for reluctance force, thereby reducing audio distortion by transmitting this signal to a power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional loudspeaker design is used, then manufacturing cost is reduced, but audio distortion increases due to reluctance force
Solution Approach 1:
The patent replaces mechanical solutions (such as shorting-rings) with a digital signal processing approach. The controller calculates and applies a corrected drive signal that compensates for reluctance force effects, substituting physical mechanical modifications with computational correction to reduce audio distortion without increasing manufacturing complexity or cost
Solution Approach 2:
The patent changes the electrical parameters of the drive signal to compensate for reluctance force. By calculating the corrected drive signal that accounts for voice-coil inductance variations and applying parameter adjustments to the drive waveform, the system reduces audio distortion without requiring physical modifications to the loudspeaker hardware
2Object-affected harmful factors
If shorting-rings are added to compensate for reluctance force, then audio distortion is reduced, but device complexity and cost increase
Solution Approach 1:
The patent substitutes mechanical compensation elements (shorting-rings) with a software-based control system. The controller computes the corrected drive signal using a physical model of the loudspeaker, replacing the need for additional mechanical components and thereby reducing device complexity while maintaining distortion reduction benefits
Solution Approach 2:
The patent introduces a controller as an intermediary between the audio source and power amplifier. This intermediary calculates and applies corrections for reluctance force effects, providing a software-based mediation that eliminates the need for additional hardware components like shorting-rings
3Device complexity
If existing solutions ignore reluctance force, then device complexity is reduced, but sound quality deteriorates
Solution Approach 1:
The patent replaces the approach of ignoring reluctance force with a computational correction system. The controller uses a physical model to calculate and apply corrected drive signals that compensate for reluctance force effects, maintaining simple hardware design while improving sound quality through digital signal processing
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously calculates the corrected drive signal based on the relationship between drive signal and speaker displacement. This feedback loop compensates for reluctance force effects in real-time, improving sound quality without adding complex hardware
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 solution effectively reduces audio distortion in loudspeaker output, improving sound quality and speech clarity without the need for costly modifications like shorting-rings, while also considering the limitations of current DSP and nonlinear control approaches.
Implementation Method 1
a magnetic field generated by a voice coil of the speaker driver
Implementation Method 2
reluctance force, a nonlinear mechanical force caused by varying voice-coil inductance
Data Source
AI summary
One embodiment provides a method for nonlinear control of a loudspeaker. The method comprises determining a target displacement of a diaphragm of a speaker driver of the loudspeaker based on a physical model of the loudspeaker and a source signal for reproduction via the speaker driver. The method further comprises determining, based on the target displacement, a corrected drive signal that compensates for action of reluctance force on the speaker driver during the reproduction of the source signal, and transmitting the corrected drive signal to a power amplifier connected to the loudspeaker. The power amplifier drives the speaker driver based on the corrected drive signal. Audio distortion generated by the speaker driver during the reproduction of the source signal is reduced based on the power amplifier output, via the corrected drive signal.