Transducer Motion Control via Impedance Sensing
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Solution Overview
Problem
Existing audio systems face challenges in maximizing sound level while minimizing size, leading to high diaphragm excursions that compromise linear loudspeaker models, and current motion control methods either require additional sensing mechanisms or significant digital signal processing.
Innovation Solution
An audio system that uses a sensor signal source to measure changes in impedance at the transducer connections beyond the audio frequency range, allowing for robust excursion measurement without additional transducer connections or high digital processing power, by applying a frequency sweep signal and sensing impedance shifts caused by diaphragm movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If diaphragm excursion is increased to maximize sound level, then acoustic power is improved, but linear loudspeaker model accuracy deteriorates
Solution Approach 1:
The patent applies feedback by measuring the actual diaphragm excursion through impedance sensing and using this information to adjust the audio signal. The measure means detects diaphragm position via impedance changes at the transducer connections, and the driver circuit uses this feedback to control the audio signal, thereby maintaining linear model accuracy while allowing high excursions for maximum acoustic power.
2Measurement precision
If additional sensing mechanisms are added to control diaphragm motion, then motion control accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by making the existing transducer connections serve dual purposes: both audio signal transmission and excursion measurement. The same two transducer connections used for audio driving also carry the sensor signal for impedance-based diaphragm position detection, eliminating the need for additional sensing mechanisms while maintaining accurate motion control.
Solution Approach 2:
The patent replaces mechanical sensing mechanisms (additional voice coils or sensors) with an electrical measurement approach. Instead of using mechanical or optical sensors to detect diaphragm position, the system uses electrical impedance measurement at the transducer connections to infer diaphragm position, thereby reducing device complexity while maintaining measurement precision.
3Measurement precision
If digital signal processing power is increased to model and control motion, then motion control accuracy is improved, but processing requirements worsen
Solution Approach 1:
The patent replaces complex digital signal processing with an electrical measurement approach. Instead of using DSP to model and compute diaphragm position from voice coil current and voltage, the system directly measures impedance at the transducer connections to obtain diaphragm position information, significantly reducing processing requirements while maintaining accuracy.
Solution Approach 2:
The patent applies self-service by using the transducer's own electrical characteristics (impedance) to provide the measurement function. The transducer's impedance naturally varies with diaphragm position, so the system exploits this inherent property to obtain position information without requiring external sensing mechanisms or complex processing, thereby reducing energy consumption.
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 optimized use of electro-acoustic transducers by accurately measuring and adjusting diaphragm excursion, reducing distortion and enhancing acoustic performance without additional hardware or processing demands.
Implementation Method 1
sense changes of the impedance of the electro-acoustic transducer for the sensor signal at the transducer connections caused by the excursion of the diaphragm
Implementation Method 2
electro-acoustic transducer with transducer connections to receive an audio signal
Data Source
AI summary
An audio system comprises an electro-acoustic transducer (1) with transducer connections (12, 13) to receive an audio signal (AS) in the audio frequency range from a driver circuit (14) and measure means (11) to measure the excursion of a diaphragm (3) of the electro-acoustic transducer (1), wherein a sensor signal source (16) provides a sensor signal (SS) at the transducer connections (12, 13) with a sensor frequency beyond the audio frequency range and in the range of the resonance frequency of the electro-acoustic transducer and, wherein the measure means (11) comprise a sensor circuit (18) to sense changes of the impedance of the electro-acoustic transducer (1) for the sensor signal (SS) at the transducer connections (12, 13) caused by the excursion of the diaphragm (3) due to the audio signal (AS).