Loudspeaker Cone Displacement Estimation via Current Transfer Function
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Solution Overview
Problem
Traditional methods for estimating loudspeaker cone displacement, especially during large movements, are inaccurate due to nonlinearities, leading to audio distortion, and existing solutions like laser measurement are expensive.
Innovation Solution
A system and method that estimates cone displacement using a discrete-time domain transfer function of the measured current, incorporating nonlinear components such as parasitic resistance associated with the voice coil, to correct audio signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional linear estimation methods are used for loudspeaker cone displacement, then the system complexity remains low, but measurement precision deteriorates during large cone movements due to nonlinearities
Solution Approach 1:
The patent transforms the continuous nonlinear differential equations governing loudspeaker behavior into discrete-time domain transfer functions with varying parameters. This allows the system to adapt to large cone movements by updating parameters based on measured current, maintaining accuracy without requiring complex real-time nonlinear solving.
Solution Approach 2:
The patent replaces direct mechanical measurement methods (such as laser measurement mentioned in background) with an electrical measurement-based estimation system. By using measured current through the voice coil and electrical parameters to infer mechanical cone displacement, it achieves accurate measurement without complex mechanical or optical measurement devices.
2Measurement precision
If nonlinear components such as parasitic resistance are incorporated into the estimation model, then measurement precision improves for large displacements, but device complexity increases
Solution Approach 1:
The patent extracts and separately models the parasitic resistance component from the overall voice coil impedance. By identifying and compensating for this specific nonlinear parameter independently, the system achieves higher accuracy in displacement estimation without needing to model all possible nonlinearities simultaneously, thus managing complexity effectively.
Solution Approach 2:
The patent uses the measured current through the voice coil as an intermediary parameter to infer cone displacement. Rather than directly measuring mechanical displacement, the system uses electrical current measurements combined with the parameter model (including parasitic resistance) as an intermediate step to calculate displacement, simplifying the measurement approach while maintaining accuracy.
3Ease of operation
If discrete-time domain transfer functions are used to model the loudspeaker, then ease of operation improves for digital signal processing, but manufacturing precision requirements increase for accurate parameter identification
Solution Approach 1:
The patent performs preliminary identification and characterization of the loudspeaker parameters (including parasitic resistance, inductance, and mechanical parameters) during system setup or calibration phases. By pre-determining these parameters and storing them in the parameter model, the system reduces the precision requirements during actual operation, as the discrete-time transfer functions use these pre-identified values rather than requiring real-time high-precision measurement of all parameters.
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 provides a reliable and cost-effective method to estimate cone displacement, enabling the development of adaptive nonlinear correctors that improve audio quality by accurately accounting for nonlinearities in loudspeaker behavior.
Implementation Method 1
an electrical current may be produced which in turn may interact with the magnetic fields to create movement of the speaker cone
Data Source
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AI summary
A displacement estimation system for estimating cone displacement of a loudspeaker may include an electrical circuit including at least one non-linear component being coupled to a mechanical circuit including at least one non-linear component, and a controller programmed to determine the cone displacement of the loudspeaker based on the at least one non-linear component by using a discrete domain transfer function of a measured current of the electrical circuit, and transmit the displacement to a corrector to correct distortion of an audio signal due to the displacement.