Fuzzy Logic Speaker Excursion Control Without Bass Loss
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Solution Overview
Problem
Conventional audio systems in portable devices face issues with loudspeaker failure due to excessive diaphragm excursion and high voice coil temperature, often exacerbated by the use of high pass filters that degrade sound quality by cutting bass frequencies.
Innovation Solution
The implementation of a system using fuzzy logic controllers to control speaker excursion by analyzing audio system parameters and feedback signals, including low-frequency content and gain, to adjust the audio output signal and prevent damage to the loudspeaker, thereby maintaining sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high pass filter is employed to reduce low-frequency components, then speaker excursion is reduced, but sound quality is degraded due to loss of bass frequencies
Solution Approach 1:
The patent changes the control parameter from simple frequency filtering to dynamic gain adjustment based on multiple input parameters (low-frequency content, feedback signals, system state). The fuzzy logic controller continuously adjusts the gain parameter to control speaker excursion while preserving bass frequencies, resolving the contradiction between protection and sound quality.
Solution Approach 2:
The patent implements a feedback mechanism where the controller receives feedback signals from the speaker system and uses them to dynamically adjust the audio output. This closed-loop control allows the system to respond to actual speaker conditions and adjust protection levels accordingly, maintaining both speaker safety and audio quality including bass frequencies.
2Power
If drive units are driven hard to their mechanical limit to achieve high volume, then loudspeaker output is increased, but excessive diaphragm excursion and high voice coil temperature cause loudspeaker failure
Solution Approach 1:
The patent applies dynamic control by continuously monitoring multiple parameters (low-frequency content, feedback current, feedback voltage, system gain) and adjusting the audio output in real-time. This dynamic approach allows the system to operate at high power levels when conditions permit while automatically reducing output when excursion or temperature limits are approached, maintaining both high volume capability and speaker durability.
Solution Approach 2:
The patent implements protective measures in advance by monitoring speaker conditions and adjusting output before damage occurs. The fuzzy logic controller predicts potential excursion or temperature issues based on current system state and input signals, and proactively reduces gain to prevent exceeding mechanical limits, thereby cushioning against potential speaker failure.
Data Source
AI summary
An audio system includes an input node for receiving an audio input signal, a signal processor coupled to the input node to receive the audio input signal, and an output node for providing an audio output signal to a speaker. The audio system includes a first fuzzy logic controller configured to receive sampled signals related to the audio input signal and a gain of the signal processor, the first fuzzy logic controller configured to determine a risk level of the audio output signal. The audio system also includes a second fuzzy logic controller configured to receive feedback signals related to the audio output signal and to determine a correction factor. Further, the audio system is configured to determine a control signal based on the risk level and the correction factor, and to adjust the audio output signal based on the control signal.