KR100992863B1 - Active acoustic absorbent and Method for minimizing accoustic reflection - Google Patents

Abstract

The present invention relates to an active sound absorbing material and a method for minimizing sound wave reflection using the same. More specifically, by using a feedback system structure in which a controller controls an acoustic signal and feeds it back to a transmitting sensor, the transmitting sensor generates an offset wave that cancels the reflected wave. The present invention relates to an active sound absorbing material having a high sound absorbing effect and exhibiting sound absorption performance comparable to a conventional passive sound absorbing material even in a high frequency band using a ceramic polymer composite material and a method of minimizing sound wave reflection using the same. .

To this end, the present invention is a reception sensor for measuring the signal of the incident wave; A transmission sensor for generating an offset wave for canceling the reflected wave of the incident wave; And a controller configured to generate a driving signal for driving the transmission sensor by controlling the phase and magnitude of the electric signal by receiving the electric signal of the acoustic wave in which the incident wave, the reflected wave, and the destructive wave are superimposed from the receiving sensor. It provides an active sound absorbing material.

Active sound absorbing material, low frequency, offset wave, feedback

Description

Active acoustic absorbent and method for minimizing acoustic reflection using it {active acoustic absorbent and Method for minimizing accoustic reflection}

The present invention relates to an active sound absorbing material and a method for minimizing sound wave reflection using the same. More specifically, by using a feedback system structure in which a controller controls an acoustic signal and feeds it back to a transmitting sensor, the transmitting sensor generates an offset wave that cancels the reflected wave. The present invention relates to an active sound absorbing material having a high sound absorbing effect and exhibiting sound absorption performance comparable to a conventional passive sound absorbing material even in a high frequency band using a ceramic polymer composite material and a method of minimizing sound wave reflection using the same. .

Underwater acoustic sensor is a device that grasps the position and distance of the object by using the reflected surface of the water reflected back by radiating sound waves. These underwater acoustic sensors are used as sonars for water and submarines, and are also fitted to most underwater weapons.

Sonar comes from 'Sound Navigation And Ranging', which in the sense refers to a hydrophone or acoustic detector. This was the case of the Asdic, organized by the British Navy during World War I, and hydrophones developed since the First World War to detect submarines, especially during and after World War II. . Electromagnetic waves such as visible light and radar waves are not transmitted in the sea, so ultrasonic waves are used to determine the distance and position of the target. The speed of sound waves transmitted in the sea varies depending on the situation of the sea, but it is about 1,500 m / s, and the sound waves reflect back when they touch an object. The sonar includes an active sonar that makes an object by sounding itself, such as an acoustic detector type, and a passive sonar that measures sound from a sound source and expresses it, such as an underwater listening machine.

Meanwhile, in order not to be detected by the underwater acoustic sensor, it is necessary to minimize the reflection of sound waves emitted from the underwater acoustic sensor. In order to minimize the reflection of sound waves on a specific wall, a passive sound absorbing material is generally made of a material having a large sound wave scattering or a large vibration resistance, and a material having a density, elasticity, and the like similar to that of a sound wave transmission medium. Such passive sound absorbing material increases loss characteristics through matching with sound wave transmission medium and sound wave scattering, and minimizes reflection by reducing acoustic energy by scattering sound waves when incident waves are transferred from the sound wave transmission medium to the sound absorbing material.

However, such a passive sound absorbing material must have a thickness that is approximately 2 to 10 times greater than the wavelength of the incident sound wave to exhibit the effect. In particular, when low frequency sound wave is incident, the thickness of the passive sound absorbing material is almost tens of centimeters to about 1 meter. In order to cover the low frequency sound waves as described above, there is a problem in that the sound absorbing material becomes too thick and the utility falls.

The present invention has been made to solve the above problems, and in particular, a high sound absorption effect can be obtained by using a thin sound absorbing material for low frequency sound waves having a very long wavelength, even in the high frequency band that does not require active sound absorption function The purpose of the present invention is to provide an active sound absorbing material having a sound absorption performance comparable to that of a passive sound absorbing material, and a method of minimizing sound wave reflection using the same.

Active sound absorbing material according to the present invention devised to achieve the above object is a receiving sensor for measuring the signal of the incident wave; A transmission sensor for generating an offset wave for canceling the reflected wave of the incident wave; And a controller configured to generate a driving signal for driving the transmission sensor by controlling the phase and magnitude of the electric signal by receiving the electric signal of the acoustic wave in which the incident wave, the reflected wave, and the destructive wave are superimposed from the receiving sensor. do.

In addition, the receiving sensor may measure a sound wave signal in which the incident wave Pi, the reflected wave Pr, and the destructive wave Pc overlap and convert the electric wave signal Es to the controller according to the following equation. .

Es = S × (Pi + Pr + Pc), S is the reception sensitivity of the receiving sensor

In addition, the controller may generate the driving signal Et from the electrical signal Es by the following equation.

Et = K × Es, K is the amplification factor of the controller

In addition, the transmission sensor may generate the offset wave Pc by the following equation according to the driving signal.

Pc = T x Et, T is the transmission sensitivity of the transmission sensor

In addition, the amplification factor K of the controller can be defined by the following equation.

K = -R / (S × T), R is the reflection coefficient of the receiving sensor

The transmitting sensor and the receiving sensor may have a flat plate shape, and the transmitting sensor and the receiving sensor may be stacked and molded.

In addition, the transmitting sensor and the receiving sensor may be a ceramic polymer composite material.

In addition, the transmitting sensor and the receiving sensor may be formed in a shape in which a piezoelectric ceramic rod is inserted into a polymer.

According to the present invention, a method for minimizing sound wave reflection includes: (a) a receiving sensor measuring an acoustic wave signal in which an incident wave Pi, a reflected wave Pr, and an offset wave Pc are superposed, and converting the sound wave signal into an electric signal Es; Delivering to; (b) the controller generating a driving signal Et for driving the transmission sensor by controlling the phase and magnitude of the electrical signal Es; And (c) generating the offset wave Pc according to the driving signal Et by the transmitting sensor.

Further, in step (b), the amplification factor K of the controller may be defined by the following equation.

K = -R / (S × T)

R is the reflection coefficient of the reception sensor, S is the reception sensitivity of the reception sensor, T is the transmission sensitivity of the transmission sensor

According to the present invention, the transmitting sensor generates an offset wave that cancels the reflected wave, so that low frequency sound waves having a very long wavelength can be obtained by using a sound absorbing material having a thin thickness.

In addition, according to the present invention, the ceramic polymer composite material has an effect of exhibiting sound absorption performance comparable to that of a conventional passive sound absorber even in a high frequency band in which an active sound absorption function is not required.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

1 is a conceptual diagram of an active sound absorbing material according to a preferred embodiment of the present invention.

Active sound absorbing material according to a preferred embodiment of the present invention, referring to Figure 1, comprises a receiving sensor 10, the controller 20 and the transmitting sensor 30. The active sound absorbing material has a multi-sensor structure in which the flat plate transmitting sensor 10 and the receiving sensor 30 are laminated and molded. In addition, the controller 20 has a feedback system structure for controlling the sound signal to feed back to the transmission sensor (30).

The reception sensor 10 and the transmission sensor 30 may be formed in a flat plate shape and molded together. In addition, the reception sensor 10 and the transmission sensor 30 may be formed of a ceramic polymer composite material. In detail, the reception sensor 10 and the transmission sensor 30 include a piezoelectric ceramic rod C inserted into a polymer part P in which a high density powder such as iron powder is added to a polymer material such as polyurethane, rubber or neoprene. It may be formed in the form. In this case, the piezoelectric ceramic bar C may be inserted into the polymer part P in a checkerboard shape. The polymer part P is excellent in high frequency sound absorption performance, and can absorb the sound wave signal of a high frequency band sufficiently even with a thin thickness. The piezoelectric ceramic rod C serves to cancel the reflected wave when the reflected wave is low. Through this, the receiving sensor 10 and the transmitting sensor 30 ensure high frequency sound absorption performance comparable to the existing passive sound absorbing material, and can cancel the low frequency reflected wave with a thin thickness.

The receiving sensor 10 is provided on the front surface of the active sound absorbing material to measure the signal of the incident wave Pi. In addition, the reception sensor 10 measures a sound wave signal in which the incident wave Pi, the reflected wave Pr, and the canceling wave Pc overlap, and converts the sound wave signal into an electrical signal Es as shown in Equation 1 to control the controller 30. To pass. At this time, the reception sensor 10 may use a method of measuring the sound pressure of the incident wave, reflected wave, decay wave to measure the sound wave signal.

Es = S × (Pi + Pr + Pc), S is the reception sensitivity of the receiving sensor

The controller 20 receives the electrical signal Es of the sound wave in which the incident wave Pi, the reflected wave Pr, and the destructive wave Pc are superimposed from the receiving sensor 10, as shown in Equation 2, as shown in Equation (2). By generating the driving signal (Et) for driving the transmission sensor 30 by controlling the phase and magnitude of the.

Et = K × Es, K is the amplification factor of the controller

The transmission sensor 30 receives the driving signal Et from the controller 20 and generates an offset wave Pc for canceling the incident wave Pi and the reflected wave Pr as shown in Equation 3 below.

Pc = T × Et, T is transmit sensitivity of transmitter

At this time, in order for the transmission sensor 30 to cancel the reflected wave so that the reflection of the sound wave is minimized by generating the offset wave, it is preferable that the magnitude of the overlapped sound wave of the reflected wave and the offset wave approaches 0 as shown in Equation (4).

Pr + Pc = R × Pi + T × Et = 0, where R is the reflection coefficient of the receiving sensor

Expanding and calculating Equation 4 is as shown in Equation 5 below.

Pr + Pc = R × Pi + T × Et

        = R × Pi + T × K × Es

        = R × Pi + T × K × S × (Pi + Pr + Pc)

        = Pi × (R + T × K × S) + T × K × S × (Pr + Pc)

Summarizing Equation 5 with respect to Pr + Pc,

Pr + Pc = Pi × (R + T × K × S) / (1-T × K × S)

In order to be Pr + Pc = 0, R + T x K x S = 0, and as a result, the amplification factor K of the controller is preferably defined as in Equation (7).

K = -R / (S × T)

When the controller 20 is defined as shown in Equation 7, the reflected wave and the cancel wave cancel each other to minimize the reflection of sound waves.

2 is a flowchart of a method for minimizing sound wave reflection according to a preferred embodiment of the present invention.

In the method for minimizing sound wave reflection according to the preferred embodiment of the present invention, referring to FIG. 2, the receiving sensor operating step (S10), the controller generating a driving signal (S20), and the transmitting sensor generates the offset wave. A step S30 is made.

Step S10 is a step in which the receiving sensor measures an acoustic wave signal in which the incident wave Pi, the reflected wave Pr, and the canceling wave Pc overlap, converts the sound wave signal into an electric signal Es, and transmits the same to the controller.

Step S20 is a step in which the controller generates a driving signal Et for driving the transmission sensor by controlling the phase and magnitude of the electrical signal Es. In this case, the controller is defined to have an amplification factor as shown in Equation 7 to generate a destructive wave causing destructive interference with the reflected wave Pr.

Step S30 is a step in which the transmitting sensor generates a cancellation wave Pc according to the driving signal Et.

As described above, according to the active sound absorbing material and the method for minimizing the sound wave signal using the same, high sound absorption effect can be obtained by using the sound absorbing material having a thin thickness even in the low frequency sound wave of very long wavelength by using electric energy, and the active sound absorbing function is required. In the absence of a high frequency band can exhibit a sound absorption performance comparable to the conventional passive sound absorbing material.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

The present invention relates to an active sound absorbing material, and can be applied to various fields including an underwater electronic warfare for deceiving an underwater acoustic sensor of an opponent.

1 is a conceptual diagram of an active sound absorbing material according to a preferred embodiment of the present invention;

2 is a flowchart of a method for minimizing sound wave reflection according to a preferred embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10-Receive Sensor 20-Controller

30-Transmitter

Claims (10)

A reception sensor measuring a sound wave signal in which the incident wave Pi, the reflected wave Pr, and the destructive wave Pc are superimposed, and converting the sound wave signal into an electric signal Es by the following equation; A controller configured to generate a driving signal by receiving an electrical signal from the receiving sensor and controlling a phase and a magnitude of the electrical signal Es; And A transmission sensor for generating a decay wave Pc for canceling the reflected wave Pr of the incident wave Pi according to a drive signal from the controller; Active sound absorbing material comprising a. Es = S × (Pi + Pr + Pc), S is the reception sensitivity of the receiving sensor delete The method of claim 1, The controller is an active sound absorbing material, characterized in that for generating the drive signal (Et) from the electrical signal (Es) by the following equation. Et = K × Es, K is the amplification factor of the controller The method of claim 1, The transmitting sensor is an active sound absorbing material, characterized in that for generating the offset wave (Pc) by the following equation according to the drive signal. Pc = T x Et, T is the transmission sensitivity of the transmission sensor The method of claim 4, wherein The amplification factor K of the controller is an active sound absorbing material, characterized in that defined by the following equation. K = -R / (S × T), R is the reflection coefficient of the receiving sensor The method of claim 1, The transmitting sensor and the receiving sensor has a flat plate shape, characterized in that the transmitting sensor and the receiving sensor is laminated and molded. The method of claim 1, The transmitting sensor and the receiving sensor is an active sound absorbing material, characterized in that the ceramic polymer composite material. The method of claim 7, wherein The transmitting sensor and the receiving sensor is an active sound absorbing material, characterized in that the piezoelectric ceramic rod is formed into a polymer shape. (a) measuring, by the receiving sensor, an acoustic wave signal in which the incident wave Pi, the reflected wave Pr, and the canceling wave Pc are superimposed, and converting the sound wave signal into an electric signal Es according to the following equation and transmitting it to the controller; (b) the controller generating a driving signal Et for driving the transmission sensor by controlling the phase and magnitude of the electrical signal Es; And (c) generating, by the transmitting sensor, an offset wave Pc for canceling the reflected wave Pr of the incident wave Pi according to the driving signal Et; Method for minimizing sound wave reflection, characterized in that it comprises a. Es = S × (Pi + Pr + Pc), S is the reception sensitivity of the receiving sensor 10. The method of claim 9, In step (b), the amplification factor K of the controller is a method of minimizing sound reflection, characterized in that defined by the following equation. K = -R / (S × T) R is the reflection coefficient of the receiving sensor, T is the transmission sensitivity of the transmitting sensor

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