JPWO2021234685A5

JPWO2021234685A5 -

Info

Publication number: JPWO2021234685A5
Application number: JP2022570613A
Authority: JP
Publication date: 2024-04-26

Claims

1. A method for controlling the operation of an electrostatic acoustic device including a membrane and an electrode disposed proximate to the membrane, the membrane configured to mechanically respond to a variable electric field emanating from the electrode when a variable audio signal voltage is applied to the electrode, the method comprising:
injecting a radio frequency varying probe signal into an input of said electrostatic acoustic device;
Detecting a current or charge signal by converting the current or charge signal into a modulated voltage signal, the current or charge signal comprising an audio signal varying at an audio frequency that modulates a radio frequency of the probe signal;
demodulating the modulated voltage signal to generate an audio output signal varying at audio frequencies;
transforming the audio output signal to generate an error signal;
inputting a control signal to the electrostatic acoustic device in response to the error signal, the phase and amplitude of the control signal being configured to at least partially cancel mechanical responses of the membrane due to ambient noise ;
A method comprising :

2. The method of claim 1, wherein the audio frequency varying audio output signal is obtained by homodyne detection of a modulated voltage signal at a radio frequency.

10. The method of claim 1, further comprising phase and frequency locking a radio frequency carrier signal responsive to the modulated voltage signal at radio frequency and the probe signal at radio frequency.

generating a synchronization signal synchronized with a radio frequency carrier of the modulated voltage signal;
outputting a probe signal responsive to the synchronization signal ;
The method of claim 1 further comprising:

The method of claim 1 , wherein demodulating the modulated voltage signal is performed using a low pass filter.

locally generating a sine wave at radio frequency;
outputting a probe signal responsive to a locally generated sine wave at radio frequency ;
The method of claim 1 further comprising:

The method of claim 6 , further comprising demodulating the modulated voltage signal by rectifying and low-pass filtering , thereby generating the audio output signal.

The method of claim 1 , wherein the control signal is configured to cause the mechanical motion of the membrane to maintain a desired acoustic output .

The method of claim 1, wherein the control signal is configured to limit the mechanical displacement of the membrane.

The method of claim 1, wherein the control signal is further configured to adjust the acoustic transparency of the electrostatic acoustic device.

1. A control circuit for controlling the operation of an electrostatic acoustic device including a membrane and an electrode disposed proximate to the membrane, the membrane configured to mechanically respond to a variable electric field emanating from the electrode when a variable audio signal voltage is applied to the electrode, the control circuit comprising:
an oscillator configured to inject a probe signal varying at a radio frequency into the electrostatic acoustic device;
a detector configured to detect a current or charge signal , the current or charge signal including an audio signal varying at an audio frequency modulating the radio frequency, the detector configured to convert the current or charge signal into a modulated voltage signal;
a demodulator configured to demodulate the modulated voltage signal to generate an audio output signal varying at audio frequencies;
a conversion circuit configured to convert the audio output signal and generate an error signal;
a controller configured to input a control signal to the electrostatic acoustic device in response to the error signal, the phase and amplitude of the control signal being configured to at least partially cancel mechanical responses of the membrane due to ambient noise ;
A control circuit comprising :

12. The control circuit of claim 11, wherein the audio frequency varying audio output signal is obtained by homodyne detection of a modulated voltage signal at a radio frequency.

The control circuit of claim 11, further comprising a phase-locked loop configured to phase and frequency lock a radio frequency carrier signal responsive to the modulated voltage signal at radio frequency and the probe signal at radio frequency.

The control circuit of claim 11 , further comprising a voltage controlled oscillator configured to generate a synchronization signal synchronous with a radio frequency carrier of the modulated voltage signal.

The control circuit of claim 14 further comprising an amplifier configured to output a probe signal responsive to the synchronization signal.

The control circuit of claim 11 , further comprising a low pass filter configured to filter and demodulate the modulated voltage signal , thereby generating an audio output signal that varies at audio frequencies.

The control circuit further comprises a local oscillator configured to generate a sine wave at a radio frequency;
the amplifier is configured to input a sine wave at a radio frequency and output the probe signal at a frequency corresponding to the sine wave;
12. The control circuit of claim 11.

20. The control circuit of claim 17, wherein the demodulator includes a rectifier and a low pass filter for generating the audio output signal.

The control circuit of claim 11 , wherein the control signal is configured to cause mechanical motion of the membrane to maintain a desired acoustic output .

The control circuit of claim 11, wherein the control signal is configured to limit the mechanical displacement of the membrane.

The control circuit of claim 11, wherein the control signal is further configured to adjust the acoustic transparency of the electrostatic acoustic device.