Speaker Diaphragm Excursion Calculation and Protection

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Solution Overview

Problem

Miniaturized speakers are prone to damage when producing louder sounds due to reaching their physical limits, necessitating a method to protect them from excessive excursion.

Innovation Solution

A speaker protection device and method that calculates the excursion of a speaker's diaphragm using a detector and processor to estimate diaphragm velocity and adjust input signals, preventing damage by determining DC resistance, impedance, and transfer functions based on feedback signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If miniaturized speakers are used to reduce size and weight, then the speaker dimensions are reduced, but the speaker becomes prone to damage when producing louder sounds

Engineering Contradiction:

Improvespeaker sizeVSAvoidspeaker durability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The system performs preliminary calculation of diaphragm excursion before the speaker is driven at high volumes. By computing the transfer function and estimating excursion in advance based on input signal characteristics, the system prevents damage before it occurs rather than reacting after damage has happened.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback signals from the speaker to calculate DC resistance and impedance, which are then used to determine the transfer function. This feedback mechanism allows the system to adapt to actual speaker conditions and accurately predict excursion, enabling protective action based on real-time speaker state.

Inventive Principle:

Principle #23Feedback

2Reliability

If real-time excursion calculation is performed to protect the speaker, then speaker protection is improved, but computational complexity increases

Engineering Contradiction:

Improvespeaker protectionVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The transfer function is calculated in advance using feedback signals and speaker parameters (DC resistance, impedance, force factor). This preliminary calculation avoids the need for complex real-time computations during signal playback, reducing computational burden while maintaining protection capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces direct physical measurement of diaphragm excursion with an electrical calculation approach. By using the transfer function derived from electrical parameters (impedance, DC resistance, force factor) and input signals, the system computes excursion mathematically rather than requiring complex mechanical sensors or measurement devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10986445B1Method for calculating excursion of diaphragm of speaker, speaker protection device and computer readable storage medium

Publication Date: 2021.04.20 REALTEK SEMICON CORP

AI summary

A method for calculating excursion of a diaphragm of a speaker, which includes: calculating a DC resistance based on a feedback signal of the speaker; calculating an impedance based on the feedback signal and the DC resistance; calculating a transfer function between a signal and a velocity of the diaphragm of the speaker based on the DC resistance, the impedance, and a force factor; and calculating the excursion of the diaphragm of the speaker based on an input signal and the transfer function.