KR101418750B1 - Optical microphone and manufacturing the same - Google Patents

Abstract

The present invention relates to an optical microphone and a manufacturing method thereof, which comprises a rectangular frame having first and second ends opposed to each other, the first end of which is opened, a plurality of faces And a sound detection unit for detecting the shaking of the diaphragm by reflecting an optical signal on one surface of the diaphragm. Therefore, the unidirectional effect can be increased and the reception of optical signal transmission can be improved to ensure reliability.

Description

[0001] OPTICAL MICROPHONE AND MANUFACTURING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an optical microphone, and more particularly, to an optical microphone capable of receiving external sound generated in one direction and a manufacturing method thereof.

In general, optical microphones are based on optical conversion technology that converts mechanical acoustic signals into optical signals through optical fibers, and it does not cause any interference by surrounding electromagnetic fields or radiation, is excellent in sensitivity to sound pressure, It has excellent response characteristics and is recognized as a next generation technology that can replace existing condenser microphones. In addition, optical microphones can be divided into intensity modulation, phase modulation, and polarization modulation according to the optical modulation method used. In addition, the optical microphone can be applied to the smooth communication between the patient and the doctor without affecting the operation of the medical equipment system such as MRI (Magnetic Resonance Imaging) and CT (Computed Tomography). In addition, And can be effectively used to remotely monitor traffic and environment in places.

Korean Patent No. 10-1181669 discloses an optical microphone in which a pair of optical fibers for transmitting light for detecting vibration of a diaphragm are stably fixed by a jig. Such optical microphones can improve the reliability by preventing errors in optical signal transmission due to an external impact.

Korean Patent Laid-Open No. 10-2007-0093506 discloses an optical microphone capable of reducing the size of a device by forming a microring resonator and a diaphragm on the same substrate to simplify the structure and realizing a stable device.

Since the conventional optical microphones have no directionality, the diaphragm vibrates according to the sound heard in all directions, and the optical transmitter and the optical receiver easily shake due to the external impact, so that the vibration of the diaphragm can not be correctly detected. It can not be converted into an electrical signal correctly, resulting in a problem of performance degradation.

Korean Patent No. 10-1181669 Korean Patent Publication No. 10-2007-0093506

An embodiment of the present invention is to provide an optical microphone and a method of manufacturing the same that can mainly receive an external sound generated in one direction.

An embodiment of the present invention is to provide an optical microphone and a manufacturing method that can facilitate manufacture through a rectangular frame.

An embodiment of the present invention is to provide an optical microphone and a method of manufacturing the optical microphone which can fix a part of the diaphragm to a rectangular frame to cause a vibration of the diaphragm even when the external sound is small.

An embodiment of the present invention is to provide an optical microphone and a method of manufacturing the optical microphone that can cause the diaphragm to shake even when the external sound is small by separating the non-fixed portion of the diaphragm from the rectangular frame.

According to an embodiment of the present invention, there is provided an optical microphone and a method of manufacturing the optical microphone which can cause the diaphragm to swing even when the external sound is small by varying the areas of the first and second stages of the rectangular frame according to the optical signal intensity.

In embodiments, the optical microphone comprises a rectangular frame having opposing first and second ends and having a first end open, a second end formed at the second end and spaced apart from a plurality of sides of the square frame, And a sound detector for reflecting the optical signal on one surface of the diaphragm to detect the shaking of the diaphragm.

The rectangular frame can fix the diaphragm to at least a part of one surface thereof. In one embodiment, the rectangular frame may fix the diaphragm in the middle of the one surface. In another embodiment, the rectangular frame can fix the diaphragm to both ends of the one surface. In another embodiment, the rectangular frame may fix the diaphragm at regular intervals in the middle of the one surface. In another embodiment, the length of the plurality of surfaces is shorter than the length of at least one surface except for the plurality of surfaces, thereby increasing the shaking of the diaphragm.

The open first end may be at least partially open.

The area of the first end of the rectangular frame may be greater than the area of the second end based on the intensity of the optical signal to control the shaking of the diaphragm. The area of the first and second stages may be designed through the following equation.

[Mathematical Expression]

S2, S1 and S2 are the area of the first and second stages, f (O_sig) is a function of the intensity of the optical signal

Among the embodiments, the optical microphone includes a diaphragm, a frame including at least a partially open first end and a second end that fixes the diaphragm in a portion opposite and opposite to the first end, And a light receiving unit receiving the optical signal reflected on one surface of the diaphragm and detecting the shaking of the diaphragm.

In one embodiment, the optical transmitter may further include a light source for transmitting an optical signal having a predetermined optical signal intensity to the optical transmitter. In one embodiment, the light receiving unit may include a light detecting unit that converts an optical signal transmitted by the light receiving unit into an electric signal.

In embodiments, a method of making a light microphone includes opposing first and second ends, the first end having an open rectangular frame disposed thereon, a plurality of sides of the square frame, A step of forming a diaphragm on the second end, and a step of coupling a sound detecting unit, which detects the shaking of the diaphragm to the arranged rectangular frame, by reflecting an optical signal on one surface of the diaphragm.

The optical microphone and related art (s) according to an embodiment of the present invention can increase the unidirectional effect by sensing the sound generated in one direction and improve the reception degree of the optical signal transmission to secure the reliability can do.

1 is a view for explaining an optical microphone according to a first embodiment of the present invention.
2 is a view for explaining an optical microphone according to a second embodiment of the present invention.
3 is a view for explaining an optical microphone according to a third embodiment of the present invention.
4 is a view for explaining an optical microphone according to a fourth embodiment of the present invention.
5 is a view for explaining an optical microphone according to a fifth embodiment of the present invention.
Figure 6 is a diagram illustrating an optical microphone that may be implemented in each of the embodiments of Figures 1-5.
7 is a view for explaining an optical microphone according to a sixth embodiment of the present invention.
8 is a view for explaining an optical transmitter and a light receiver which can be implemented in each of the embodiments shown in Figs. 1 to 5 and Fig.
FIG. 9 is a flowchart illustrating a manufacturing process of an optical microphone that can be implemented in each of the embodiments shown in FIGS. 1 to 5 and 7.

The description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas. Also, the purpose or effect of the present invention should not be construed as limiting the scope of the present invention, since it does not mean that a specific embodiment should include all or only such effect.

Meanwhile, the meaning of the terms described in the present application should be understood as follows.

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It should be understood that the singular " include "or" have "are to be construed as including a stated feature, number, step, operation, component, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In each step, the identification code (e.g., a, b, c, etc.) is used for convenience of explanation, the identification code does not describe the order of each step, Unless otherwise stated, it may occur differently from the stated order. That is, each step may occur in the same order as described, may be performed substantially concurrently, or may be performed in reverse order.

The present invention can be embodied as computer-readable code on a computer-readable recording medium, and the computer-readable recording medium includes all kinds of recording devices for storing data that can be read by a computer system . Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and also implemented in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present application.

1 is a view for explaining an optical microphone according to a first embodiment of the present invention.

Referring to FIG. 1, the optical microphone 100 includes a rectangular frame 110, a diaphragm 120, and a sound detection unit 130.

The rectangular frame 110 may be formed in a hexahedron having an opened first end 111 and the first end 111 may be formed in a direction opposite to the diaphragm 120 of the rectangular frame 110. The opened first end 111 of the rectangular frame 110 transmits the external sound to the sound detection unit 130 to reflect the optical signal to the diaphragm 120 formed at the second end of the rectangular frame, As shown in FIG.

The rectangular frame 110 may be formed in the shape of a cube or a rectangular parallelepiped, and the second end of the rectangular frame 110 may face the first end 111. The second stage may form the diaphragm 120 to vibrate the diaphragm 120 in accordance with an external sound generated mainly in one direction. Here, one direction may correspond to the opposite direction of the opened first end 111 (for example, the upper part of Fig. 1).

The rectangular frame 110 may be formed of PDMS (Polydimethyl-siloxane), which is flexible and has elasticity and can reduce the influence of an electromagnetic field. This is because PDMS can be shaken even with less vibration.

The rectangular frame 110 can fix the diaphragm 120 on one side 112 of the second stage. That is, the rectangular frame 110 can separate the diaphragm 120 from the plurality of surfaces. Here, the plurality of surfaces may correspond to the remaining surfaces except the one surface 112.

The diaphragm 120 is formed at a second end facing the first end 111 of the rectangular frame 110 and can be moved away from the plurality of faces of the rectangular frame 110 according to the external sound. That is, the diaphragm 120 may be fixed to the second end surface 112 of the rectangular frame 110.

The diaphragm 120 may shake according to the external sound and reflect the optical signal. In one embodiment, the thickness of the diaphragm 120 may correspond to about 0.1 um to about 10 um so that it can be shaken by external fine sound pressure. In one embodiment, the diaphragm 120 may be embodied as a metal (e.g., gold, silver, aluminum, copper, nickel, etc.) or coated with a metal so as to have a high reflectivity.

The diaphragm 120 can generate vibration in proportion to the intensity of the external sound (sound wave). For example, when the intensity of the external sound is increased, the vibration of the diaphragm 120 becomes large, and the sound detection unit 130 detects a relatively large vibration of the diaphragm 120 in accordance with the optical signal reflected by the diaphragm 120 can do. In contrast, when the intensity of the external sound is small, the vibration of the diaphragm 120 is reduced, and the sound detector 130 detects a relatively small vibration of the diaphragm 120 according to the optical signal reflected by the diaphragm 120 can do.

The sound detector 130 generates an optical signal and reflects the optical signal on one surface of the diaphragm 120 to detect the shake of the diaphragm 120.

8 is a view for explaining an optical transmitter and a light receiver included in the sound detector shown in FIG.

8, the optical microphone 100 includes a diaphragm 810, a frame 820, an optical transmitter 830, and a light receiver 840. Here, since the diaphragm 810 and the frame 820 are substantially the same as the diaphragm 120 and the rectangular frame 110 shown in FIG. 1, detailed description will be omitted.

The optical transmitter 830 includes a light source 831 and can transmit an optical signal to one surface of the diaphragm 810. The light source unit 831 may generate an optical signal having an intensity of a predetermined optical signal and may be implemented as a light emitting diode or the like. In one embodiment, the optical signal may use light of a wavelength between 1,550 um and 1,600 um. This is because the light of the corresponding wavelength has the least transmission loss and is in good agreement with the characteristics of the optical fiber.

The light receiving unit 840 includes an optical detecting unit 841 and receives the optical signal transmitted by the optical transmitting unit 830 through the diaphragm 810 as a reflected optical signal. That is, the light receiving unit 840 can receive the reflected optical signal when the diaphragm 810 reflects the optical signal, and the diaphragm 810 can vibrate in proportion to the intensity of the external sound. The photodetector 841 may be implemented as a photodiode and may convert a reflected optical signal into an electrical signal.

In one embodiment, the light transmitting portion 830 and the light receiving portion 840 may be inclined toward the center of the second end of the rectangular frame 820. That is, the optical transmitter 830 and the optical receiver 840 may be spaced apart from each other, and a virtual extension line may be intersected at a lower portion of the diaphragm 810.

1, the sound detector 130 includes an optical transmitter 830 that transmits an optical signal to the diaphragm 120 through an optical fiber and a light receiver 830 that receives an optical signal reflected from the diaphragm 120, And a light receiving unit 840.

2 is a view for explaining an optical microphone according to a second embodiment of the present invention.

Referring to FIG. 2, the optical microphone 200 includes a rectangular frame 210, a diaphragm 220, and a sound detection unit 230. The rectangular frame 210, the diaphragm 220 and the sound detection unit 230 are substantially the same as the sound detection unit 130 shown in FIG. 1, As shown in FIG.

The rectangular frame 210 may fix the diaphragm 220 to the intermediate portion 212 of the second end surface and the intermediate portion 212 of the second end surface may have a predetermined depth (for example, 1 mm to 3 mm) . This fixing can detect the horizontal shaking of the diaphragm 220 with respect to the external sound, and can also help to easily detect the shaking of the diaphragm 220 even if the intensity of the external sound is low.

In one embodiment, the middle 212 of the second single plane may be designed in consideration of the external environment, and in an environment where the noise is relatively low, the middle 212 of the second plane may be reduced and conversely, In a large environment, the middle 212 of the second stage may be increased.

3 is a view for explaining an optical microphone according to a third embodiment of the present invention.

Referring to FIG. 3, the optical microphone 300 includes a rectangular frame 310, a diaphragm 320, and a sound detection unit 330. The rectangular frame 310 and the diaphragm 320 may be omitted because they are substantially the same as the sound detector 130 shown in FIG. As shown in FIG.

The rectangular frame 310 can secure the diaphragm 320 to both ends 312 of the second end surface and the both ends 312 of the second end surface can be fixed to a predetermined degree (for example, 1 mm to 3 mm). This fixation can detect the horizontal shaking of the diaphragm 320 with respect to the external sound, and can also help to easily detect the shaking of the diaphragm 320 even if the intensity of the external sound is low.

In one embodiment, both ends 312 of the second single side may be designed in consideration of the external environment, and in an environment with relatively little noise, both ends 312 of the second single side may be reduced, In a relatively large environment, both ends 312 of the second stage surface can be increased.

4 is a view for explaining an optical microphone according to a fourth embodiment of the present invention.

Referring to FIG. 4, the optical microphone 400 includes a rectangular frame 410, a diaphragm 420, and a sound detection unit 430. Since the rectangular frame 410, the vibration plate 420 and the sound detection unit 430 are substantially the same as the sound detection unit 130 shown in FIG. 1, As shown in FIG.

The rectangular frame 410 may fix the diaphragm 420 at a predetermined interval 412 in the middle of the second end surface and may have a predetermined interval 412 in the middle of the second end surface, 1 mm to 3 mm). Such fixing can detect the horizontal shaking of the diaphragm 420 with respect to the external sound, and can also help to easily detect the shaking of the diaphragm 420 even if the intensity of the external sound is small.

In one embodiment, the constant spacing 412 in the middle of the second single plane may be designed in consideration of the external environment, and in an environment of relatively low noise, the constant spacing 412 may be reduced in the middle of the second single plane Conversely, in a relatively high noise environment, the constant interval 412 may be increased in the middle of the second stage.

5 is a view for explaining an optical microphone according to a fifth embodiment of the present invention.

Referring to FIG. 5, the optical microphone 500 includes a rectangular frame 510, a diaphragm 520, and a sound detection unit 530. Since the rectangular frame 510, the diaphragm 520 and the sound detection unit 530 are substantially the same as the sound detection unit 130 shown in FIG. 1, the description will be omitted and the rectangular frame 510 and the diaphragm 520, As shown in FIG.

The lengths of the plurality of surfaces except for the first end 511 and the second end of the rectangular frame 510 are shorter than the length of at least one surface except for the plurality of surfaces, so that the vibration of the diaphragm 520 can be increased.

The a, b, and c planes of the rectangular frame 510 are spaced apart from the diaphragm 520 by r, so that the diaphragm 520 is positioned at a position corresponding to the optical signal transmitted from the optical transmitter 830, r The shaking can be increased by an interval of.

For example, the a-, b-, and c-planes of the square frame 510 are 0.1 μm to 10 μm apart from the diaphragm 520 by 0.1 μm to 10 μm according to the optical signal transmitted from the optical transmitter 830, the shake of the diaphragm 520 can be increased by a certain amount.

Figure 6 is a diagram illustrating an optical microphone that may be implemented in each of the embodiments of Figures 1-5.

6A and 6B, the optical microphone 600 includes a rectangular frame 610, a diaphragm 620, and a sound detection unit 630. Since the rectangular frame 610, the diaphragm 620 and the sound detecting unit 630 are substantially the same as the diaphragm 120 shown in FIG. 1, the description will be omitted, and the rectangular frame 610 and the sound detecting unit 630, As shown in FIG.

The first end 611 of the rectangular frame 610 can be partially opened and the sound detection unit 630 can pass through the open holes 611-1, 611-2, and 611-3.

In one embodiment, the first end 611 of the rectangular frame 610 is formed with a small hole 611-1 in the middle, and the hole 611-1 is formed by a light transmitting portion 830 and a light receiving portion 840). The holes 611-1 can prevent a case where the sound detecting unit 630 is shaken due to an external impact so that the vibration of the diaphragm 620 can not be sensed.

In another embodiment, the first end 611 of the rectangular frame 610 is formed with at least two small holes 611-2, 611-3 in the middle, The second hole 611-3 can pass through the light receiving unit 611-3, and the second hole 611-3 can pass through the light receiving unit 611-3. The first hole 611-2 and the second hole 611-3 can prevent a case where the sound detection unit 630 is shaken due to an external impact and the vibration of the diaphragm 620 is not sensed.

7 is a view for explaining an optical microphone according to a sixth embodiment of the present invention.

Referring to FIG. 7, the optical microphone 700 includes a rectangular frame 710, a diaphragm 720, and a sound detection unit 730. The rectangular frame 710, the diaphragm 720 and the sound detection unit 730 are substantially the same as the diaphragm 120 and the sound detection unit 130 shown in FIG. 1, The configuration is mainly described.

The square frame 710 can be realized by increasing the area of the first end 711 to be larger than the area of the second end. The area of the first stage 711 can be controlled to increase the area of the second stage based on the intensity of the optical signal transmitted by the optical transmitter 830 to control the shaking of the diaphragm 720.

The area of the first end 711 and the second end of the rectangular frame 710 can be designed by the following equation.

[Mathematical Expression]

S1 = f (O_sig) * S2

(Where S1 and S2 are the areas of the first and second stages, f (O_sig) is a function of the intensity of the optical signal)

The first end 711 of the rectangular frame 710 has a larger area when the intensity of the optical signal is higher than that of the optical signal when the intensity of the optical signal is lower, Can be reduced.

The area of the first stage 711 is determined by multiplying the area of the second end of the rectangular frame 710 by the intensity of the optical signal, that is, the intensity of the optical signal reflected by the optical transmitter 830, Can be determined in proportion to the area of the two stages.

The intensity of the optical signal reflected by one side of the diaphragm 720 in the optical transmitter 830 increases as the area of the rectangular frame 710 increases and the optical receiver 840 vibrates the diaphragm 720 Can be largely detected.

The smaller the area of the rectangular frame 710 is, the smaller the intensity of the optical signal reflected on one surface of the diaphragm 720 in the optical transmitter 830 becomes, and the optical receiver 840 detects the shake of the diaphragm 720 .

8 is a view for explaining an optical transmitter and a light receiver which can be implemented in each of the embodiments shown in Figs. 1 to 5 and Fig.

8, the optical microphone 100 includes a diaphragm 810, a frame 820, an optical transmitter 830, and a light receiver 840. Here, since the diaphragm 810 and the frame 820 are substantially the same as the diaphragm 120 and the rectangular frame 110 shown in FIG. 1, detailed description will be omitted.

The optical transmitter 830 includes a light source 831 and can transmit an optical signal to one surface of the diaphragm 810. The light source unit 831 may generate an optical signal having an intensity of a predetermined optical signal and may be implemented as a light emitting diode or the like. In one embodiment, the optical signal may use light of a wavelength between 1,550 um and 1,600 um. This is because the light of the corresponding wavelength has the least transmission loss and is in good agreement with the characteristics of the optical fiber.

The light receiving unit 840 includes an optical detecting unit 841 and receives the optical signal transmitted by the optical transmitting unit 830 through the diaphragm 810 as a reflected optical signal. That is, the light receiving unit 840 can receive the reflected optical signal when the diaphragm 810 reflects the optical signal, and the diaphragm 810 can vibrate in proportion to the intensity of the external sound. The photodetector 841 may be implemented as a photodiode and may convert a reflected optical signal into an electrical signal.

In one embodiment, the light transmitting portion 830 and the light receiving portion 840 may be inclined toward the center of the second end of the rectangular frame 820. That is, the optical transmitter 830 and the optical receiver 840 may be spaced apart from each other, and a virtual extension line may be intersected at a lower portion of the diaphragm 810.

1, the sound detector 130 includes an optical transmitter 830 that transmits an optical signal to the diaphragm 120 through an optical fiber and a light receiver 830 that receives an optical signal reflected from the diaphragm 120, And a light receiving unit 840.

Hereinafter, the operation of the optical microphone according to one embodiment of the present invention will be described in detail.

FIG. 9 is a flowchart illustrating a manufacturing process of an optical microphone that can be implemented in each of the embodiments shown in FIGS. 1 to 5 and 7.

Referring to FIG. 9, the first stage 821 with the first end 821 and the second end facing each other positions the opened rectangular frame 820 (step S101). The diaphragm 810 is formed on the second end of the diaphragm 810 so as to be apart from the plurality of sides of the square frame 820 according to the external sound (step S102) So as to obtain the shake caused by

The diaphragm 810 may be fixed to a second end face 822 facing the open first end 821 of the rectangular frame 820 and the diaphragm 810 may be fixed to a plurality of faces of the quadrangular frame 820 It shakes away. Even if the external sound intensity is low, it is possible to easily detect the shaking of the diaphragm 810.

The optical transmitter 830 reflects the optical signal on one side of the diaphragm 810 and couples the optical signal to the square frame 820 so that the optical receiver 840 detects the shake of the diaphragm 810 (step S103).

The light detecting unit 841 in the light receiving unit 840 and the light source unit 831 in the light transmitting unit 830 may be positioned at the lower end of the coupling surface (i.e., the outer position of the rectangular frame 820) have. This is because the sizes of the light source unit 831 and the light detecting unit 841 may be larger than the inside of the rectangular frame 820.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as defined by the following claims It can be understood that

100, 200, 300, 400, 500, 600, 700, 800: Optical microphones
110, 210, 310, 410, 510, 610, 710, 820:
111, 211, 311, 411, 511, 611, 711, 821:
120, 220, 320, 420, 520, 620, 720, 810:
130, 230, 330, 430, 530, 630, 730:
830:
831:
840:
841:

Claims (13)

A rectangular frame including opposing first and second ends and the first end opened;
A diaphragm fixed to a part of the second end and shaking away from a plurality of surfaces of the rectangular frame according to unidirectional external sound; And
And a sound detector for detecting a vibration of the diaphragm, the diaphragm including an optical transmitter for transmitting an optical signal to one surface of the diaphragm, and a light receiver for receiving an optical signal reflected by the diaphragm,
The sound detection unit
And the optical transmitter and the light receiver are separated from each other.
2. The apparatus of claim 1, wherein the square frame
And the diaphragm is fixed to at least a part of one surface thereof.
3. The apparatus of claim 2, wherein the square frame
And the diaphragm is fixed in the middle of the one surface.
3. The apparatus of claim 2, wherein the square frame
And the diaphragm is fixed to both ends of the one surface.
5. The apparatus of claim 4, wherein the square frame
And the diaphragm is fixed at regular intervals in the middle of the one surface.
The method of claim 1, wherein the lengths of the plurality of faces
Wherein the vibration plate is shorter than the length of at least one surface except for the plurality of surfaces, thereby increasing the vibration of the diaphragm.
The method of claim 1, wherein the open first end
And at least partially open.
2. The method of claim 1, wherein the area of the first end of the square frame
And controlling the shaking of the diaphragm by increasing the area of the second stage based on the intensity of the optical signal.
9. The method of claim 8 wherein the area of the first and second stages is
And is designed through the following equation.

[Mathematical Expression]
S2, S1 and S2 are the area of the first and second stages, f (O_sig) is a function of the intensity of the optical signal
A diaphragm that vibrates according to a unidirectional external sound;
A frame including a first end at least partially open and a second end for securing the diaphragm in a portion opposite and opposite to the first end;
An optical transmitter disposed independently of the frame and transmitting an optical signal to one surface of the diaphragm; And
And a light receiving unit disposed independently of the frame and separated from the light transmitting unit to receive an optical signal reflected on one surface of the diaphragm to detect a shake of the diaphragm.
11. The apparatus of claim 10, wherein the optical transmitter
And a light source unit for transmitting an optical signal having a predetermined optical signal intensity to the optical transmitter.
The apparatus of claim 10, wherein the light receiver
And an optical detector for converting the optical signal transmitted by the optical receiver into an electrical signal.
Disposing an open rectangular frame including first and second opposing ends and the first end;
Forming a diaphragm at a portion of the second stage that is shaken away from a plurality of surfaces of the square frame according to a unidirectional external sound; And
A step of disposing a light transmitting part for transmitting an optical signal on one surface of the diaphragm and a light receiving part for receiving an optical signal reflected by the diaphragm so as to be separated from each other and arranging the light transmitting part and the light receiving part independently from the square frame Wherein the light source is a light source.

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