Speaker Audio Gain Control for Voice Coil Thermal Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional temperature protection methods for miniature speakers in portable devices, such as mobile phones, result in over-protection and sudden changes in sound quality due to the use of fixed gain attenuation, leading to suboptimal speaker performance and subjective experience.
Innovation Solution
An audio signal processing method that implements a joint gain control policy based on dynamic power and temperature constraints, adjusting the input signal using power and temperature constraint gains calculated from real-time voice coil resistance and temperature measurements to prevent overloading and maintain optimal sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steady-state power threshold is used to control transient input power, then speaker temperature is protected, but speaker volume and performance are reduced due to over-protection
Solution Approach 1:
The patent applies dynamics by transitioning from a static steady-state power threshold to a dynamic transient power threshold that adapts to real-time speaker conditions. The transient power threshold is calculated based on current voice coil temperature and thermal characteristics, allowing the protection mechanism to adjust continuously rather than using a fixed threshold that causes over-protection.
Solution Approach 2:
The patent changes the parameter used for power limiting from steady-state power threshold to transient power threshold. This parameter change enables more precise control because the transient threshold reflects the actual thermal state and transient thermal capacity of the voice coil, rather than relying on a conservative steady-state value that is far below the true transient input power capability.
2Reliability
If fixed gain attenuation is applied for temperature protection, then speaker temperature is controlled, but sound quality deteriorates due to sudden changes
Solution Approach 1:
The patent applies dynamics by replacing fixed gain attenuation with dynamic gain adjustment. The power constraint gain is calculated in real-time based on the ratio of transient power threshold to actual input power, allowing smooth, continuous adaptation of the attenuation level rather than abrupt fixed reductions that degrade auditory experience.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual input power and comparing it with the transient power threshold, then adjusting the power constraint gain accordingly. This closed-loop control ensures that gain attenuation is applied only when necessary and at the precise level needed, maintaining sound quality while protecting the speaker.
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 maximizes speaker volume while protecting the voice coil from overheating, ensuring a smooth and enhanced auditory experience by accurately distinguishing various signals and scenarios, thus preventing sudden volume changes and optimizing temperature protection.
Implementation Method 1
The moving coil speaker has characteristics of having very low electro-acoustic conversion efficiency (usually less than 1%) and generating heat
Data Source
AI summary
The present application provides a method of audio signal processing. The method comprises obtaining a voice coil direct current resistance of a speaker. The method further comprises obtaining an audio input signal to be input into the speaker. The method further comprises determining an audio input power based on the voice coil direct current resistance and the audio input signal. The method further comprises obtaining a thermal model of the speaker, and determining a transient power threshold based on the audio input power and the thermal model. The method further comprises determining a power constraint gain based on the audio input power and the transient power threshold. The method further comprises obtaining a voice coil temperature of the speaker. The method further comprises determining a temperature constraint gain based on the voice coil temperature and an upper operating temperature limit of the speaker. The method further comprises adjusting the audio input signal based on the power constraint gain and the temperature constraint gain, to obtain a target signal.