Loudspeaker Current Feedback Circuit for Distortion Compensation
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Solution Overview
Problem
Conventional loudspeakers face challenges in producing high-quality sound with minimal distortion and excessive diaphragm displacement, often requiring expensive materials and enclosures, which can lead to damage, especially in micro-speakers.
Innovation Solution
A system comprising a speaker, an amplifier, a current sensor, and a compensator circuit that applies a transfer function matching the speaker's resistance and inductance to provide feedback and adjust the audio signal, reducing diaphragm displacement and tonal distortion while enhancing sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high quality materials and properly designed speaker enclosures are used to maximize sound quality, then sound quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a feedback circuit that senses current through the speaker and applies a transfer function to generate a compensation signal. This compensation signal is injected into the audio input signal to pre-distort the waveform, canceling out distortion introduced by the speaker's electrical and mechanical characteristics. This feedback mechanism improves sound quality without requiring complex physical speaker enclosures or high-quality materials.
2Reliability
If pre-distortion is injected into the audio signal to cancel distortion, then sound quality is improved, but device complexity increases
Solution Approach 1:
The system uses a feedback circuit that senses the actual current through the speaker and generates a compensation signal by applying a transfer function that models the speaker's resistance and inductance. This compensation signal is injected into the audio input to pre-distort the waveform. The feedback approach automatically adapts to the speaker's characteristics without requiring complex manual calibration or multiple processing stages.
3Power
If diaphragm displacement is increased to produce louder sounds, then sound volume is improved, but the risk of speaker damage increases
Solution Approach 1:
The patent applies preliminary anti-action by injecting a compensation signal that pre-distorts the audio waveform in the opposite direction of the distortion that would be introduced by high diaphragm displacement. The transfer function is designed to counteract the nonlinearities in the speaker's response, allowing the system to operate at higher power levels without causing excessive diaphragm displacement or mechanical stress, thereby preventing damage while maintaining high sound 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 solution enables high-quality sound production with reduced diaphragm displacement, minimal distortion, and increased sound volume, allowing for cost-effective loudspeaker designs that protect against damage and maintain sound quality across the frequency range.
Implementation Method 1
A current sensor senses current through the speaker and produces a current sensor signal indicative thereof
Implementation Method 2
A compensator circuit applies a transfer function to the current sensor signal to produce a compensation signal... the transfer function matching resistance and/or inductance of the speaker
Implementation Method 3
the transfer function matching resistance and/or inductance of the speaker
Implementation Method 4
An amplifier amplifies the analog audio input signal and produces an amplified analog input signal
Implementation Method 5
The loudspeaker can include a voice coil, a magnet, and a diaphragm. The audio signals are applied to the voice coil, which results in the diaphragm moving the cone back and forth at high speeds to create sound waves
Implementation Method 6
the diaphragm moving the cone back and forth at high speeds to create sound waves
Data Source
AI summary
One example includes a system that is comprised of a speaker, an amplifier, a current sensor, and a compensator circuit. The speaker produces audio in response to an amplified analog input signal received at a speaker input. The amplifier receives an analog audio input signal and provides the amplified analog audio input signal to the speaker input. The current sensor senses current passing through the speaker and provides a current sensor signal indicative thereof. The compensator circuit applies a transfer function to the current sensor signal to provide a compensation signal as feedback into the analog audio input signal, the transfer function matching at least one of resistance and inductance of the speaker.