KR20110050255A - Mobile terminal - Google Patents

Abstract

PURPOSE: A mobile terminal is provided to limit inflow rate of a foreign material by performing a waterproof function through a plurality of vibration plate. CONSTITUTION: A speaker module(140) includes a vibration plate(141), a frame(142), an auxiliary diaphragm(143), and an assistant frame(144). The vibration plate outputs acoustic with vibration. The vibration plate is electrically connected to a circuit board. The frame is formed as a hollow body. The vibration plate is arranged in the hollow part of the frame. In a location which the auxiliary diaphragm is separated with the vibration plate, the auxiliary vibration diaphragm is arranged for covering the vibration plate. The auxiliary diaphragm can be formed by synthetic resin. A plurality of grooves is formed in a single-side of the auxiliary diaphragm.

Description

[0001] MOBILE TERMINAL [0002]

The present invention relates to a mobile terminal provided with a waterproof sound output unit.

The terminal can move And can be divided into a mobile / portable terminal and a stationary terminal depending on whether the mobile terminal is a mobile terminal or a mobile terminal. The mobile terminal can be divided into a handheld terminal and a vehicle mount terminal according to whether the user can directly carry the mobile terminal.

As the functions of the mobile terminal are diversified, the mobile terminal is implemented in the form of a multimedia device having complicated functions such as photographing and photographing of a moving picture, reproduction of a music or video file, reception of a game and broadcasting.

Thus, as the function of the mobile terminal as the multimedia device is enhanced, the sound quality of the sound output from the mobile terminal when listening to music or moving images can be considered as an important factor in designing the mobile terminal.

Various new attempts have been made in terms of hardware or software to enhance the functionality of these design elements. Therefore, as one of the above-mentioned attempts, a waterproof sound output portion can be considered.

It is an object of the present invention to provide a mobile terminal having an acoustic output unit that is waterproof while maintaining sound quality.

Another object of the present invention is to provide an audio output means of a mobile terminal in which the inflow of foreign matter is restricted.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a mobile terminal includes a sound output unit formed in a main body of a mobile terminal, the sound output unit including a diaphragm for outputting sound by vibration, An auxiliary diaphragm arranged to cover the diaphragm at a position spaced apart from the diaphragm; and an auxiliary diaphragm connected to the frame to guide the diaphragm toward the auxiliary diaphragm And an auxiliary frame surrounding the auxiliary diaphragm to form an air layer that transmits the vibration between the diaphragm and the auxiliary diaphragm. A plurality of grooves forming a closed curve may be formed on one surface of the auxiliary diaphragm.

As one example related to the present invention, the auxiliary frame includes a housing and a seat portion. The housing is coupled to the frame and comprises a closed curve. The seat portion is formed in the inner periphery of the housing, and is made just against the frame, and the edge of the auxiliary diaphragm is seated. The edge of the auxiliary diaphragm and the seat portion may be formed so as to be in surface contact with each other so as to be waterproof.

As another example related to the present invention, the sound output section includes a cover. The cover is formed to cover the edge of the auxiliary diaphragm, is mounted on the auxiliary frame, and passes through the center so that the sound is emitted. An acoustic emission hole may be formed on one surface of the terminal body to emit the sound, and the cover may be disposed to cover an opening of the acoustic emission hole.

According to another embodiment of the present invention, the auxiliary frame includes first and second auxiliary frames stacked on each other, and the auxiliary diaphragm includes first and second auxiliary diaphragms. The first auxiliary diaphragm defines the air layer together with the frame, the diaphragm and the first sub frame. The second auxiliary diaphragm is spaced apart from the first auxiliary diaphragm and forms a closed space to be laminated on the air layer together with the first auxiliary diaphragm, the first auxiliary frame and the second auxiliary frame.

The mobile terminal according to the present invention configured as described above enables waterproofing of the mobile terminal through a plurality of diaphragms. In addition, through this, the inflow of foreign matter can be restricted, and a material cost can be reduced because a waterproof filter is unnecessary.

Further, according to the present invention, the vibration is transmitted through the air layer, thereby realizing an acoustic output structure that is closed to the outside while reproducing sound close to the original sound.

Hereinafter, a mobile terminal related to the present invention will be described in detail with reference to the drawings. In the present specification, the same or similar reference numerals are given to different embodiments in the same or similar configurations. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

The mobile terminal described in this specification may include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a PDA (Personal Digital Assistants), a PMP (Portable Multimedia Player), navigation and the like. However, it will be understood by those skilled in the art that the configuration according to the embodiments described herein may be applied to a fixed terminal such as a digital TV, a desktop computer, and the like, unless the configuration is applicable only to a mobile terminal.

1 is a perspective view of a mobile terminal according to an exemplary embodiment of the present invention.

The disclosed mobile terminal 100 has a terminal body of a watch-like shape. However, the present invention is not limited thereto, and can be applied to various structures such as a slide type, a folder type, a swing type, and a swivel type in which a bar type or a plurality of bodies are relatively movably coupled.

The body 110 of the watch-type mobile terminal is connected to a band 120 which is formed to be worn on the wrist. The bands 120 are connected to both sides of the body 110.

The main body 110 includes a wireless communication module 181 (see FIG. 8) and is configured to transmit / receive a wireless signal to / from the mobile communication base station.

The outer surface of the main body 110 is formed by a case 111. The case 111 is formed of a dielectric, for example, a synthetic resin or the like. A cover 112 (see Fig. 2) may be disposed under the case 111. Fig. The case 111 and the cover 112 form an internal space in which various electronic components are embedded.

The display unit 113, the sound output unit 114, the image input unit 115, or the user input unit 116 may be disposed in the main body of the terminal, mainly the case 111.

The display unit 113 occupies most of the main surface of the case 111. The display unit 113 may include a display 113c (see FIG. 3). The display 113c may be, for example, a liquid crystal display, a thin film transistor-liquid crystal display, an organic light-emitting diode, a flexible display, Dimensional display (3D display), and the like. The display 113c can be configured to be transparent so that the outside can be viewed through the display 113c. This can be referred to as a transparent display, and a typical example of the transparent display is TOLED (Transparent OLED) and the like.

There may be two or more display units 113 depending on the implementation mode of the watch-type mobile terminal. The display unit 113 may be configured to selectively display the image information and the time information by inputting user information.

The display unit 113 may further include a touch sensor so as to receive input of information by a user's touch. The touch sensor can be configured to detect the touch input pressure as well as the touch input position and area. The display unit 113 equipped with the touch sensor forms a touch screen.

The sound output unit 114 and the image input unit 115 are disposed in a region adjacent to one end of the both ends of the display unit 113.

The sound output unit 114 may be implemented in the form of a speaker module 140 (see FIG. 3) capable of outputting sounds. The speaker module 140 may include a receiver or a loudspeaker.

The image input unit 115 may be implemented in the form of a camera module 115b (see FIG. 3) for capturing an image or a moving image of a user.

The sound input unit 187 (see FIG. 8) may be disposed in a region adjacent to the other end of both ends of the display unit 113. The sound input unit 187 may be implemented in the form of, for example, a microphone 187a (see FIG. 3) in order to receive a user's voice, other sounds, and the like. The sound input unit 187 may be disposed on the side surface of the terminal body.

The user input unit 116 is a device operated to receive a command for controlling the operation of the watch-type mobile terminal. For example, the user input unit 116 may be implemented by a dome switch or a touch screen that can receive a command or information by a push or touch operation of a user, a wheel that rotates the key, a jog method, Or the like.

The user input unit 116 may be disposed on the side surface of the case 111. [ However, the present invention is not limited to this, and the touch screen can be used as a user input unit in addition to the output device.

The contents input by the user input unit 116 can be variously set. For example, the user input unit 116 may be configured to receive commands such as start or end input, size adjustment of sound output from the sound output unit 114, and the like. The touch screen may be configured to receive information such as numbers, characters, and symbols.

The interface 188 (see FIG. 8) may be disposed on the side or back of the watch-type mobile terminal.

The interface 188 is a path for allowing the watch-type mobile terminal to exchange data with an external device. For example, the interface 188 may be a wired or wireless connection port for connection to an earphone, a port for short range communication (e.g., an IrDA port, a Bluetooth port, a wireless port, Lan port, etc.), or power supply terminals for supplying power to the watch mobile terminal. The interface 188 may be a card socket that accepts an external card such as a subscriber identification module (SIM) or a user identity module (UIM), a memory card for information storage, and the like.

2 is a rear perspective view of the watch-type mobile terminal of FIG.

The cover 112 includes a rear cover 112a and a cover 112b. The rear cover 112a engages with the case 111 to define the inner space. The cover 112b is mounted on the rear cover 112a so as to cover the inner space.

The rear cover 112a and the cover 112b may be formed by injection molding synthetic resin or may be formed of a metal material such as stainless steel (STS) or titanium (Ti).

A power supply unit 170 for supplying power to at least one component of the watch-type mobile terminal is formed on the cover 112 side. The power supply unit 170 may include, for example, a rechargeable battery or the like to supply power.

The power supply unit 170 may be configured to be charged from an external power source. The cover 112 is formed with a connection terminal 172 for connecting the power supply unit 170 and the external power supply unit.

3 is an exploded view of the watch-type mobile terminal of FIG.

3, the watch-type mobile terminal has a built-in space in which a cover 112 is coupled to a case 111 to incorporate components, a support frame 132 is mounted in the built-in space, The electronic components associated with the function of the support frame 132 are supported or mounted to the support frame 132.

Referring to this figure, a window 113a is mounted on the front surface of the case 111. [

The window 113a is made of a material through which light can be transmitted, for example, a light transmitting synthetic resin, a tempered glass, or the like. However, the window 113a may include a portion that can not transmit light. Such a portion is a material that can not transmit light or is a surface-treated region such that light can not be transmitted.

The case 111 is provided with a keypad 141 to be pressed and operated by the user to receive a control command.

At least a part of the case 111 is formed so as to form an inclined portion 131 in a direction in which the wrist is wound. The inclined portion 131 is formed to transmit and receive a radio signal and includes an antenna that operates in association with the wireless communication module 181 (see FIG. 8).

A support frame 132 is disposed in the space defined by the front surface and the side surface of the case 111. At least one electronic component may be coupled to the support frame 132. The support frame 132 may be formed of a material having higher rigidity or higher rigidity than the material of the case 111. For example, if the case 111 is formed of a synthetic resin such as polycarbonate or the like, the support frame 132 may be formed of stainless steel stronger than this. The support frame 132 reinforces the strength and rigidity of the case 111 with a small thickness.

Referring to this figure, the support frame 132 may be formed to support the display 113c on the front surface and insert the battery on the rear surface.

The display 113c is disposed corresponding to the window 113a. Accordingly, the time information output from the display 113c can be recognized from the outside. The window 113a may have an area corresponding to the display 113c. The display 113c and the window 113a can constitute the display unit 113 (see Fig. 1).

A touch sensor (not shown) capable of recognizing the user's touch may be mounted between the display 113c and the window 113a. However, the present invention is not limited thereto. For example, the touch sensor may be mounted on one side of the window 113a. The touch sensor may be configured to generate an electrical change, for example, a change in capacitance or potential gradient depending on a user's touch.

A printed circuit board 119 may be mounted on the side of the support frame 132 so as to be inclined with respect to the display. The circuit board 119 may be a flexible circuit board and the switch 143 is formed on the circuit board 119 to correspond to the keypad 141.

A speaker module 140 and a camera module 115b are mounted on one side of the support frame 132 and a microphone 187a is mounted on the other side. An acoustic hole 140a is formed in the case 111 so that the sound of the speaker is emitted to correspond to the speaker module 140. [ The speaker module 140 and the acoustic hole 140a are combined with each other to constitute the acoustic output section 114 (see FIG. 1). An acoustic filter 140b for filtering the foreign substances through the acoustic hole 140a is disposed to cover the acoustic hole 140a. Between the acoustic hole 140 and the speaker module, The ring member 140c can be mounted.

Hereinafter, the sound output unit 114 will be described in detail with reference to FIGS. 4, 5A, and 5B. 5A is a cross-sectional view of the watch-type mobile terminal taken along line V-V in FIG. 1, FIG. 5B is a cross-sectional view of the speaker module 140 in FIG. 5A, (140).

Referring to these drawings, the speaker module 140 includes a diaphragm 141, a frame 142, an auxiliary diaphragm 143, and an auxiliary frame 144.

The diaphragm 141 is formed to output sound by vibration. The diaphragm 141 is electrically connected to the circuit board 118 and can be driven by an electromagnet through a current change. A magnet (not shown) may be disposed adjacent to the diaphragm 141, and the diaphragm 141 vibrates due to a change in the electromagnetic field between the diaphragm 141 and the magnet.

The frame 142 is formed of a hollow body and the diaphragm 141 is disposed in a hollow portion of the frame 142 to hold the edge of the diaphragm 141. The frame is mounted on the support frame 132 (see Fig. 3) and is formed in a ring shape.

The auxiliary diaphragm 143 is disposed to cover the diaphragm 141 at a position spaced apart from the diaphragm 141. The auxiliary diaphragm 143 may be formed of synthetic resin, for example, polyphenylene sulfide (PPS).

A plurality of grooves 143a are formed on one surface of the auxiliary diaphragm 143. The grooves 143a form a closed curve, and the radius is gradually increased. Accordingly, the vibration of the diaphragm 141 can be more effectively transmitted to the auxiliary diaphragm 143.

The auxiliary frame 144 is connected to the frame 142 and protrudes from the frame 142 toward the auxiliary diaphragm 143. The auxiliary frame 144 surrounds the auxiliary vibration plate 143 and forms an air layer 145 for transmitting the vibration of the vibration plate 141 between the vibration plate 141 and the auxiliary vibration plate 143. The diaphragm 141, the frame 142, the auxiliary diaphragm 143 and the auxiliary frame 144 are combined to form a closed space defining the air layer 145 together. When the diaphragm 141 vibrates under the control of the circuit board 119, the pressure in the air layer 145 changes and the pressure change of the air layer 145 is transmitted to the auxiliary diaphragm 143, thereby regenerating the sound source .

The auxiliary frame 144 includes a housing 144b and a seating portion 144c.

The housing 144b engages with the frame 142 and is formed of a closed curve.

A protrusion 142a protruding toward the auxiliary frame 144 is formed on the outer periphery of the frame 142 and a groove 144a formed on the outer circumference of the housing 144b to be engaged with the protrusion 142a. As the protrusion 142a is inserted into the groove 144a, the air layer 145 is more easily sealed.

The seating portion 144c is formed on the inner periphery of the housing 144b and is made to be opposed to the frame 142 only. The edge of the auxiliary diaphragm 143 is seated in the seating portion 144c and the edge of the auxiliary diaphragm 143 and the seating portion 144c are formed in surface contact with each other so as to be waterproof. The auxiliary diaphragm 143 is coupled to, for example, the seating portion 144c through bonding. The above structure makes the air layer 145 tightly sealed, and water tightness of the speaker module 140 is realized through the sealing. A ring member 140c is fitted to the outer circumference of the housing 144b to provide waterproofing between the speaker module 140 and the acoustic hole 140a (see FIG. 3).

Referring to these figures, the speaker module 140 includes a cover 146 formed to cover the edge of the auxiliary vibration plate 143.

The cover 146 penetrates the center so as to emit sound due to the vibration of the auxiliary diaphragm 143 and is arranged to cover the acoustic hole 140a. More specifically, the cover 146 is disposed to face the acoustic filter 140b (see FIG. 3), and is formed to cover the edge of the auxiliary vibration plate 143 at the seating portion 144c.

6A and 6B are an exploded view and a cross-sectional view, respectively, showing other embodiments of the sound output portion according to the present invention.

Referring to these drawings, the speaker module 240 is composed of two-stage air layers 245a and 245b stacked on each other.

The auxiliary frame 244 includes first and second auxiliary frames 251 and 252 stacked on each other and the auxiliary vibration plate 243 includes first and second auxiliary vibration plates 253 and 254 arranged to correspond to each other .

The first auxiliary diaphragm 253 defines the first air layer 245a together with the frame 242, the diaphragm 241 and the first auxiliary frame 251. [

The second auxiliary diaphragm 254 is spaced apart from the first auxiliary diaphragm 253 and the first auxiliary diaphragm 253 and the first auxiliary frame 251 and the second auxiliary frame 252, Thereby forming an enclosed space to be laminated on the first substrate 245a. A second air layer 245b is formed in the closed space.

The cover 246 is mounted on the second sub frame 252 so as to cover the edge of the second auxiliary diaphragm 254 and the ring member 240c is arranged to surround the periphery of the second sub frame 252.

The vibration of the diaphragm 241 is transmitted to the first auxiliary diaphragm 253 by the first air layer 245a and the vibration of the first auxiliary diaphragm 253 is transmitted to the second air layer 253. [ Is transmitted to the second auxiliary vibration plate 254 by the second auxiliary vibration plate 245b, and the vibration of the second auxiliary vibration plate 254 forms a sound reproduction mechanism for generating sound. In addition, the waterproof performance of the speaker module 240 can be further improved by forming the double closed space.

Referring to these drawings, an acoustic filter 240b is mounted at the center of the cover 246. [ The acoustic filter 240b is formed of a flat plate having a plurality of through holes, and filters the foreign matter from entering through the acoustic holes 240a. As described above, as the acoustic filter 240b is integrated with the speaker module 240, the watch-type mobile terminal 200 can be configured more compactly.

7A and 7B are graphs showing the sound pressure and sound distortion rates of the watch-type mobile terminal according to the present invention, respectively.

Referring to FIG. 7A, in the watch-type mobile terminal disclosed in the present invention, the sound pressure is maintained at a low frequency of 1000 Hz. Referring to FIG. 7B, a distortion of 10% or less is maintained above 1000 Hz. Therefore, the sound output unit of the present invention has abundant bass output capability and can reproduce a sound close to the original sound.

8 is a block diagram of a mobile terminal according to the present invention.

8, a mobile terminal according to an exemplary embodiment of the present invention includes a display unit 113, an audio output unit 114, an image input unit 115, a user input unit 116, a power supply unit 170, 180, a wireless communication module 181, a memory 184, a broadcast receiving module 185, a sensing unit 186, an acoustic input unit 187, and an interface 188.

The control unit 180 typically controls the overall operation of the mobile terminal. For example, voice communication, data communication, video communication, and the like.

The wireless communication module 181 transmits / receives a wireless signal to / from a mobile communication base station through an antenna. A transmission unit 162 for transmitting and receiving voice data, character data, video data, and control data under the control of the control unit 180 and for modulating and transmitting a signal to be transmitted for this purpose; 183).

The user input unit 116 provides the control unit 180 with key input data that the user inputs for controlling the operation of the terminal. The user input unit 116 includes a dome switch, a touch pad (static / static), a jog wheel, a jog switch, and the like.

The image input unit 115 processes image frames such as still images or moving images obtained by the image sensor in the video communication mode or the photographing mode. The processed image frame is converted into image data that can be displayed on the display unit 113 and output to the display unit 113.

The image frame processed by the image input unit 115 is stored in the memory 184 under control of the control unit 180 or transmitted to the outside through the wireless communication module 181. [

The sound input unit 187 receives an external sound signal by a microphone in a communication mode, a recording mode, a voice recognition mode, and the like, and processes it as electrical voice data. The processed voice data is converted into a form that can be transmitted to the mobile communication base station via the wireless communication module 181 in the communication mode, and is output to the wireless communication module 181. In the record mode, the processed voice data is output to be stored in the memory 184. [

The sound input unit 187 may be implemented with various noise reduction algorithms for eliminating noise generated in the process of receiving an external sound signal.

The display unit 113 displays and outputs information processed by the mobile terminal. For example, when the mobile terminal is in the call mode, a UI (User Interface) or a GUI (Graphic User Interface) associated with the call is displayed and output under the control of the control unit 180. When the mobile terminal is in the video communication mode or the photographing mode, the control unit 180 displays and displays the photographed image, the UI, and the GUI. When the display unit 113 includes a touch screen, the display unit 113 is used as an input device in addition to the output device.

The sound output unit 114 outputs sound data received from the wireless communication module 181 under the control of the control unit 180 in the call signal reception mode, the communication mode or the recording mode, the voice recognition mode, Converts the stored sound data and outputs it to the outside.

Also, the sound output unit 114 outputs a sound signal related to a function (e.g., a call signal reception sound, a message reception sound, etc.) performed in the mobile terminal.

The sensing unit 186 senses the current state of the mobile terminal, such as the open / close state of the mobile terminal, the position of the mobile terminal, whether or not the user touches the mobile terminal, and generates a sensing signal for controlling the operation of the mobile terminal. For example, if the mobile terminal is in the form of a slide phone, it senses whether the slide phone is opened or closed, and outputs the sensing result to the controller 180 to control the operation of the terminal. And a sensing function related to whether or not the power supply unit 170 is powered on, whether the interface 188 is connected to an external device, and the like.

The interface 188 may be a universal serial bus (USB) interface, such as a wired / wireless headset other than a mobile terminal, an external charger, a wired or wireless data port, a card socket (e.g. a memory card, a SIM / UIM card) It serves as an interface with the device. The interface 119 receives data from an external device or receives power from the external device, and transmits the data to each component in the mobile terminal or transmits data in the mobile terminal to an external device.

The memory 184 may store a program for processing and controlling the control unit 180 and may have a function for temporarily storing input / output data (e.g., a phone book, a message, a still image, .

In addition, a program for controlling the operation of the mobile terminal related to the present invention is stored in the memory 184

Such memory 184 includes the concept of a generally known hard disk, card type memory (e.g., SD or XD memory), flash memory, RAM, ROM, and the like.

The broadcast receiving module 185 receives broadcast signals transmitted through satellite or terrestrial waves, converts the received broadcast signals into broadcast data formats that can be output to the sound output unit 114 and the display unit 113, and outputs the broadcast data formats to the controller 180. In addition, the broadcast receiving module 185 receives additional data (e.g., EPG (Electric Program Guide), channel list, etc.) related to broadcasting. The broadcast data and the additional data converted by the broadcast receiving module 185 may be stored in the memory 184. [

The power supply unit 170 receives external power and internal power under the control of the controller 180, and supplies power necessary for operation of the respective components.

The above-described mobile terminal is not limited to the configuration and the method of the embodiments described above, but all or a part of the embodiments may be selectively combined so that various modifications may be made to the embodiments.

1 is a front perspective view of a watch-type mobile terminal according to an embodiment of the present invention;

FIG. 2 is a rear perspective view of the watch-type mobile terminal of FIG. 1;

FIG. 3 is an exploded view of the watch-type mobile terminal of FIG. 1;

FIG. 4 is an exploded view of a speaker module for the watch-type mobile terminal of FIG. 3;

5A is a cross-sectional view of a watchdog mobile terminal taken along line V-V of FIG.

Fig. 5B is an enlarged view of the speaker module of Fig. 5A. Fig.

6A and 6B are an exploded view and a cross-sectional view, respectively, showing other embodiments of the acoustic output portion according to the present invention.

FIGS. 7A and 7B are graphs showing the sound pressure and sound distortion rates of each watch-type mobile terminal according to the present invention.

8 is a block diagram of a mobile terminal according to the present invention;

Claims (7)

And a sound output unit formed on the terminal body, A diaphragm for outputting sound by vibration; A frame which is formed of a hollow body and in which the diaphragm is disposed in a hollow portion to hold an edge of the diaphragm; An auxiliary diaphragm disposed to cover the diaphragm at a position spaced apart from the diaphragm; And And an auxiliary frame connected to the frame and protruding from the frame toward the auxiliary diaphragm and surrounding the auxiliary diaphragm to form an air layer for transmitting the vibration between the diaphragm and the auxiliary diaphragm. The method according to claim 1, The sub- A housing coupled to the frame, the housing comprising a closed curve; And And a seating portion which is formed on the inner periphery of the housing and which is formed simply with respect to the frame and on which the edge of the auxiliary diaphragm is seated. 3. The method of claim 2, Wherein an edge of the auxiliary diaphragm and the seat portion are in surface contact with each other so as to be waterproof. The method according to claim 1, The sound output unit includes: Further comprising a cover formed to cover an edge of the auxiliary diaphragm and mounted on the auxiliary frame, the cover passing through the center so that the sound is emitted. 3. The method of claim 2, An acoustic hole is formed on one surface of the terminal body to emit the sound, Wherein an acoustic filter is installed at the center of the cover to filter foreign substances from entering through the acoustic holes. The method according to claim 1, Wherein a plurality of grooves forming a closed curve are formed on one surface of the auxiliary diaphragm. The method according to claim 1, Wherein the auxiliary frame includes first and second auxiliary frames stacked on each other, The auxiliary diaphragm A first auxiliary diaphragm defining the air layer together with the frame, the diaphragm and the first sub frame; And And a second auxiliary diaphragm spaced apart from the first auxiliary diaphragm and forming a closed space stacked on the air layer together with the first auxiliary diaphragm, the first auxiliary frame, and the second auxiliary frame.

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