Speaker Amplifier Circuit for In-Situ Peak Impedance Detection
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Solution Overview
Problem
Existing speaker failure notification devices require a dedicated physical quantity measuring device to apply an alternating-current voltage and measure impedance, resulting in a large circuit for impedance measurement.
Innovation Solution
A semiconductor device with a modulation circuit, amplifier circuits, and a peak frequency detection circuit that modulates signals for sound reproduction and generates test signals to detect the peak frequency of the sound reproduction device's impedance in a separate operation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated physical quantity measuring device is used to apply alternating-current voltage and measure impedance, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the impedance measurement function with the existing amplifier circuit by utilizing its output terminals and internal components. The amplifier's output terminals are used to apply test signals to the speaker, and the same terminals are used to measure impedance, eliminating the need for separate dedicated measuring devices and reducing overall circuit complexity while maintaining measurement precision
Solution Approach 2:
The amplifier circuit is made multi-functional by enabling it to perform both its primary function of amplifying audio signals and its secondary function of measuring speaker impedance. The circuit switches between normal amplification mode and impedance measurement mode, allowing the same hardware to serve multiple purposes and reducing the need for additional dedicated components
2Reliability
If the amplifier circuit operates in normal amplification mode, then sound reproduction quality is improved, but the ability to measure impedance accurately deteriorates
Solution Approach 1:
The amplifier circuit dynamically switches between two operational states: normal amplification mode for high-quality sound reproduction and impedance measurement mode for accurate impedance detection. This dynamic switching allows the circuit to optimize its performance for the current task, ensuring that sound reproduction quality is maintained during audio playback while enabling accurate impedance measurement when needed
Solution Approach 2:
The system employs periodic action by alternating between normal amplification operation and impedance measurement operation. During normal audio playback, the amplifier operates in amplification mode, and at predetermined intervals or when triggered, it switches to measurement mode to detect speaker impedance, thereby achieving both high-quality sound reproduction and periodic impedance monitoring
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
Enables accurate detection of the frequency range including the peak impedance frequency of the sound reproduction device, allowing for effective failure detection and reduced circuit size for peak frequency detection.
Implementation Method 1
a modulation circuit configured to modulate a signal based on a sound source signal to output a first modulated signal and a second modulated signal
Implementation Method 2
a first amplifier circuit configured to output a first amplified signal obtained by amplifying the first modulated signal to the first output terminal
Implementation Method 3
a peak frequency detection circuit configured to measure a potential difference between the first output terminal and the second output terminal, and detect a frequency range including a peak frequency that is the frequency of the test signal at which an impedance of the sound reproduction device peaks
Data Source
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AI summary
Provided is a semiconductor device. In a first operation mode, a first modulated signal is input to a plurality of inverter circuits provided in a first amplifier circuit, and a second modulated signal is input to a plurality of inverter circuits provided in a second amplifier circuit. In a second operation mode, a test signal generation circuit modulates a test signal to generate a third modulated signal and a fourth modulated signal. The third modulated signal is input to some of the plurality of inverter circuits provided in the first amplifier circuit, and outputs of other inverter circuits have high impedances. The fourth modulated signal is input to some of the plurality of inverter circuits provided in the second amplifier circuit, and outputs of other inverter circuits have high impedances. A peak frequency detection circuit detects a frequency range including a frequency of the test signal at which an impedance of a sound reproduction device peaks.