Speaker Driver Current-Spectrum Self-Test for Defect Detection
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Solution Overview
Problem
Conventional methods for testing speaker performance are costly and time-consuming, relying on acoustic measurements that require dedicated equipment and are not sensitive enough to detect subtle defects, especially in noisy environments.
Innovation Solution
A smart speaker driver system that measures the current frequency spectrum of the speaker using a load current sense ADC and DSP, allowing for built-in self-testing by generating test signals and averaging current measurements to enhance signal-to-noise ratio and identify defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic measurement methods are used to test speaker performance, then measurement capability is provided, but the method is costly, time-consuming and requires dedicated external equipment
Solution Approach 1:
The speaker driver system performs self-diagnosis by using its own internal components (amplifier, ADC, processor) to generate test signals and measure its own performance characteristics, eliminating the need for external test equipment. The system tests itself by applying test signals through the amplifier and analyzing the resulting current measurements.
Solution Approach 2:
The amplifier and ADC components serve dual purposes: they function as normal audio signal processing components during operation, and as test measurement components when diagnostic modes are activated. The same hardware infrastructure is used for both audio playback and performance characterization.
2Measurement precision
If conventional acoustic measurement methods are used, then speaker performance can be assessed, but the methods are not sensitive enough to detect subtle defects
Solution Approach 1:
The patent replaces acoustic measurement methods with electrical current measurement methods. Instead of measuring sound output acoustically, the system measures the electrical current drawn by the speaker voice coil, which provides more sensitive and direct information about speaker performance and defects.
Solution Approach 2:
The system uses the amplifier output current as an intermediary measurement parameter to infer speaker performance characteristics. By measuring the current through the voice coil and analyzing its frequency spectrum, the system can detect defects without directly measuring acoustic output.
3Measurement precision
If current measurements are taken without averaging, then real-time measurement is achieved, but signal-to-noise ratio is insufficient
Solution Approach 1:
The system applies periodic test signals (such as sine waves or swept sine signals) through the amplifier to the speaker. By using repetitive, periodic excitation signals, the system can accumulate measurements over multiple cycles and average them to improve signal-to-noise ratio while maintaining reasonable measurement time.
Solution Approach 2:
The system performs preliminary signal processing by applying known test signals with specific frequency content before analysis. This allows the measurement system to prepare the signal in advance and know what frequency components to expect, enabling more effective filtering and averaging to improve measurement precision.
4Ease of manufacture
If built-in self-testing is implemented, then manufacturing costs are reduced, but the system complexity increases
Solution Approach 1:
The amplifier, ADC, and processor components serve dual purposes: they function as normal audio signal processing components during operation, and as test measurement components when diagnostic modes are activated. The same hardware infrastructure is used for both audio playback and performance characterization.
Solution Approach 2:
The speaker driver system performs self-diagnosis by using its own internal components (amplifier, ADC, processor) to generate test signals and measure its own performance characteristics, eliminating the need for external test equipment.
Data Source
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AI summary
A speaker driver (100) comprising an amplifier (104), configured to receive a test signal that comprises a plurality of equivalent test-blocks, and provide measurement-signalling for a speaker (102) at the amplifier output. The measurement-signalling comprising a plurality of measurement-blocks, wherein each of the measurement-blocks corresponds to the output of the amplifier for one of the plurality of test-blocks. The speaker driver also includes an output-current-sensor (130) configured to: measure a current level of the measurement-signalling, and provide sensed-signalling that comprises a plurality of sensed-blocks, wherein each of the plurality of sensed-blocks corresponds to one of the plurality of measurement-blocks of the measurement-signalling. The speaker driver further includes a processor (120) configured to either: (a) combine the plurality of sensed-blocks to provide a time-averaged-block; and determine a frequency-spectrum of the time-averaged-block; or (b) determine a frequency-spectrum of each of the plurality of sensed-blocks to provide a plurality of frequency-spectrum-sensed-blocks; and combine the plurality of frequency-spectrum-sensed-blocks to provide a time-averaged-frequency-spectrum-block.