Loudspeaker Membrane State Feedback for Phase Shift Control
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Solution Overview
Problem
Conventional loudspeakers cannot accurately maintain a constant phase shift between the driving signal and the produced sound across different frequencies, limiting their ability to precisely control the membrane's position, velocity, and acceleration, which is essential for faithful sound reproduction.
Innovation Solution
Determining the actual membrane state values, including position, velocity, and acceleration, to directly calculate the driving signal applied to the voice coil, ensuring that the entire membrane state is used for precise control, allowing for accurate conversion of the driving signal and maintaining a constant phase shift across the frequency spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional loudspeaker control methods are used, then the loudspeaker can operate across the frequency spectrum, but the phase shift between driving signal and produced sound varies with frequency, preventing precise membrane position control
Solution Approach 1:
The patent implements feedback by detecting actual membrane state values (position, velocity, acceleration) and using this information to determine the driving signal. The detecting device measures the membrane's actual state, and this feedback is used to adjust the driving signal applied to the voice coil, enabling precise control of the membrane's position, velocity, and acceleration while maintaining a constant phase shift across different frequencies.
2Manufacturing precision
If only single membrane state values are used for control, then the control system is simpler, but the sound reproduction accuracy is insufficient
Solution Approach 1:
The patent merges multiple membrane state values (position, velocity, and acceleration) into a unified actual membrane state that is used to determine the driving signal. By combining these three state values and using them together in the control process, the system achieves highly accurate sound reproduction while managing complexity through integrated processing.
3Reliability
If the membrane is controlled to follow predetermined position and velocity profiles, then sound accuracy improves, but the phase shift becomes frequency-dependent, limiting real-time control capability
Solution Approach 1:
The patent applies dynamics by making the driving signal determination adaptive and responsive to real-time membrane state conditions. Rather than using fixed predetermined profiles, the system dynamically adjusts the driving signal based on detected actual membrane position, velocity, and acceleration, enabling both accurate sound reproduction and flexible real-time control across varying frequency conditions.
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 enables highly accurate sound reproduction by maintaining a constant phase shift and accurately reproducing the desired membrane state, improving the loudspeaker's control and frequency response, particularly in applications requiring precise sound profiles like noise compensation in vehicles.
Implementation Method 1
an electro-dynamic loudspeaker having a voice coil and a membrane as sound source... The driving signal is normally applied to the voice coil of the loudspeaker, which is operatively connected with the membrane and which displaces the membrane commensurate with the driving signal
Implementation Method 2
it is known to detect within the context of the 'Motional Feedback' principle an actual membrane state value the membrane of the loudspeaker
Data Source
AI summary
In a method for operating a loudspeaker device having at least one loudspeaker, at least one actual membrane state parameter of a membrane of the loudspeaker is detected by a detecting device. An actual membrane state of the membrane based on the following actual membrane state parameters: actual membrane position (xactual), actual membrane speed (vactual) and actual membrane acceleration (aactual), is determined from the at least one detected actual membrane state parameter (xactual, aactual) and is directly used to determine a driving signal (U(t)) that is applied to the voice coil of the loudspeaker. The voice coil is operatively connected to the membrane. A loudspeaker device being operated with this method and a device for noise compensation are also disclosed.