Patent Publication Number: US-11026012-B1

Title: Earphone including tuning means

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to an earphone. 
     2. Discussion of Related Art 
     An earphone includes a speaker unit which generates a sound wave in a housing. Also, the earphone includes a cover including a nozzle with which an ear tip is coupled. The cover is coupled with the housing. Korean Patent Publication No. 10-2017-0098527 (published on Aug. 30, 2017, and hereinafter, referred to as the document) discloses an earphone including a nozzle. In the document, a front housing including the nozzle is coupled with a rear housing including a speaker unit. 
     Meanwhile, in the document, a tuning hole configured to change a tone may be provided in a cover portion corresponding to the front housing including the nozzle. Some of sound waves generated by the speaker unit are discharged through the tuning hole such that a tone or sound feature of a sound output through the nozzle may be changed. The tuning hole is disposed in a front surface of the cover portion and exposed to the outside. Accordingly, there is a problem that water or foreign substances flow into the housing of the earphone through the tuning hole. Also, there is a problem that external noise causes a loss of sounds of the earphone. 
     RELATED ART DOCUMENT 
     [Patent Document] 
     Korean Patent Publication No. 10-2017-0098527 (published on Aug. 30, 2017) 
     SUMMARY OF THE INVENTION 
     The present invention is directed to providing an earphone capable of changing a tone and preventing water or foreign substances from flowing into a housing of the earphone. 
     The present invention is also providing an earphone capable of fundamentally excluding sound interference from external noise. 
     Aspects of the present invention are not limited to the above-stated aspects and other unstated aspects of the present invention will be understood by those skilled in the art from a following disclosure. 
     According to an aspect of the present invention, there is provided an earphone in which a tuning means is provided in a speaker unit. The earphone includes a housing, the speaker unit disposed in the housing, a cover coupled with the housing and including a nozzle, a first space portion disposed in front of the speaker unit, and a second space portion disposed in the rear of the speaker unit and partitioned off from the first space portion. Here, the speaker unit includes a cylindrical yoke with an open top, a magnet fixed to a bottom surface of an inside of the yoke, a plate fixed to a top surface of the magnet, a voice coil disposed between an inner circumference of the yoke and outer circumferences of the magnet and the plate, a vibration plate disposed above the plate and to which the voice coil is fixed, a cap coupled with the yoke, and a frame coupled with the yoke and the cap. Here, the frame includes a tuning hole disposed to pass through from an inner circumferential surface to an outer circumferential surface of the frame, a pipe conduit disposed between the outer circumferential surface of the frame and an inner wall of the housing and configured to communicate with the tuning hole and the second space portion, and a tuning portion which covers the tuning hole. 
     The frame may include an accommodation groove concavely formed in the outer circumferential surface thereof and a tuning groove located above the accommodation groove and concavely formed. Here, the tuning hole may be disposed in the tuning groove, and the tuning portion may be disposed in the accommodation groove and cover the tuning hole. 
     The speaker unit may have a cylindrical shape, and the tuning hole may be disposed along a radial direction of the speaker unit. 
     The tuning portion may include a body, which comes into contact with the accommodation groove, and a tuning material disposed on the body. Here, the tuning material may be disposed to be aligned with the tuning groove and spaced apart from the tuning hole. 
     A top end of the accommodation groove may be connected to a top surface of the frame, and a bottom end of the accommodation groove may be a stepped surface. 
     The speaker unit may further include a damper, and the damper may be disposed on a top end of the frame and come into contact with an inner surface of the cover. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing exemplary embodiments thereof in detail with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates an earphone according to a first embodiment; 
         FIG. 2  is an exploded view of the earphone shown in  FIG. 1 ; 
         FIG. 3  is a side cross-sectional view of the earphone shown in  FIG. 1 ; 
         FIG. 4  is an exploded view of a speaker unit shown in  FIG. 2 ; 
         FIG. 5  is a side cross-sectional view of the speaker unit shown in  FIG. 2 ; 
         FIG. 6  is a view illustrating the speaker unit including a tuning hole and a tuning portion; 
         FIG. 7  is a view illustrating the speaker unit with which the tuning portion is coupled; 
         FIG. 8  is a side cross-sectional view of the speaker unit in which a size of the tuning hole and a size of a tuning groove are shown; 
         FIG. 9  is a side cross-sectional view of the speaker unit; 
         FIG. 10  is a side cross-sectional view of the earphone shown in  FIG. 1 ; 
         FIG. 11  is an exploded view of an earphone according to a second embodiment; 
         FIG. 12  is a side cross-sectional view of the earphone shown in  FIG. 11 ; 
         FIG. 13  is a view illustrating a speaker unit and a tuning portion shown in 
         FIG. 11 ; 
         FIG. 14  is a side cross-sectional view of the speaker unit shown in  FIG. 11 ; 
         FIG. 15  is a side cross-sectional view of the earphone shown in  FIG. 11 ; 
         FIG. 16  is an exploded view of an earphone according to a third embodiment; 
         FIG. 17  is a side cross-sectional view of the earphone shown in  FIG. 16 ; 
         FIG. 18  is an exploded view of a speaker unit shown in  FIG. 16 ; 
         FIG. 19  is a view illustrating the speaker unit and the tuning portion shown in  FIG. 18 ; and 
         FIG. 20  is a side cross-sectional view of the earphone shown in  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The aspects, particular advantages, and novel features of the present invention will become apparent from a detailed description of exemplary embodiments with reference to the attached drawings. Also, the terms used in the specification and the claims should not be limited to general or lexical meanings and should be interpreted as meanings and concepts coinciding with the technical concept of the present invention on the basis of a principle in which the inventor can appropriately define the concept of the terms to describe the invention in the best manner. Also, in a description of the present invention, a detailed description of well-known functions or components of the related art will be omitted when it is deemed to obscure the essence of the present invention. 
     Hereinafter, an earphone according to an embodiment will be described in detail with reference to the attached drawings. 
       FIG. 1  illustrates an earphone according to a first embodiment,  FIG. 2  is an exploded view of the earphone shown in  FIG. 1 , and  FIG. 3  is a side cross-sectional view of the earphone shown in  FIG. 1 . 
     Referring to  FIGS. 1 to 3 , the earphone according to the first embodiment includes a housing  100 , a speaker unit  200 , and a cover  300 . Hereinafter, the terms such as front and front side includes a meaning of indicating a direction of facing the cover  300  on the basis of the speaker unit  200 , and the term such as rear indicates a direction of facing the housing  100  on the basis of the speaker unit  200 . 
     The housing  100  accommodates the speaker unit  200  therein. A cable is led into the housing  100 . The led cable is connected to the speaker unit  200 . Overall, the housing  100  has a cylindrical member with an open front. The cover  300  may be coupled with a front of the housing  100 . The front of the housing  100  has an annular shape. 
     The speaker unit  200  converts an electrical signal into a sound wave which is a voice signal. 
     The cover  300  is coupled with the housing  100 . The cover  300  covers the housing  100  being opened. The cover  300  includes a nozzle  310 . The nozzle  310  is a place with which an ear tip is coupled. 
     While the speaker unit  200  is accommodated in the housing  100  and the cover  300 , an inner space of the housing  100  and the cover  300  is divided into a first space portion S 1  and a second space portion S 2  by the speaker unit  200 . 
     Referring to  FIG. 3 , the first space portion S 1  refers to a space disposed in front of the speaker unit  200 . In detail, the first space portion S 1  means a space surrounded by inner surfaces of the speaker unit  200  and the cover  300  while the speaker unit  200  is accommodated in the housing  100  and the cover  300 . The first space portion S 1  communicates with the nozzle  310 . 
     The second space portion S 2  means a space disposed in the rear of the speaker unit  200 . In detail, the second space portion S 2  means a space surrounded by inner surfaces of the speaker unit  200  and the housing  100  while the speaker unit  200  is accommodated in the housing  100  and the cover  100 . 
     The speaker unit  200  of the earphone  10  according to the first embodiment may include a first unit  200 A and a second unit  200 B. A sound wave generated by the first unit  200 A is transmitted to the first space portion S 1 . A sound wave generated by the second unit  200 B is transmitted to the second space portion S 2 . 
       FIG. 4  is an exploded view of the speaker unit shown in  FIG. 2 , and  FIG. 5  is a side cross-sectional view of the speaker unit shown in  FIG. 2 . 
     Referring to  FIGS. 3 to 5 , the speaker unit  200  includes a yoke  210 . 
     The yoke  210  is a cylindrical member with an open top. The yoke  210  performs a function of forming a magnetic circuit as well as accommodates magnets  220 A and  220 B. 
     The speaker unit  200  includes two magnets  220 A and  220 B. A first magnet  220 A is included as the first unit  200 A, and a second magnet  220 B is included as the second unit  200 B. The first magnet  220 A may be accommodated inside the yoke  210 , and the second magnet  220 B may be accommodated outside the yoke  210 . The first magnet  220 A may have a cylindrical shape, and the second magnet  220 B may have an annular shape. The second magnet  220 B may be disposed outside the first magnet  220 A. 
     The speaker unit  200  includes two plates  230 A and  230 B. A first plate  230 A is included as the first unit  200 A, and a second plate  230 B is included as the second unit  200 B. The first plate  230 A is disposed on a top surface of the first magnet  220 A. The second plate  230 B is disposed on a top surface of the second magnet  220 B. 
     The speaker unit  200  includes two voice coils  240 A and  240 B. A first voice coil  240 A is included as the first unit  200 A, and a second voice coil  240 B is included as the second unit  200 B. The first voice coil  240 A is fixed to a first vibration plate  250 A, and a lower part thereof is disposed between an inner circumference of the yoke  210  and an outer circumference of each of the first magnet  220 A and the first plate  230 A. The second voice coil  240 B is fixed to a second vibration plate  250 B, and an upper part thereof is disposed between an outer circumference of the yoke  210  and an inner circumference of each of the second magnet  220 B and the second plate  230 B. 
     The speaker unit  200  includes two vibration plates  250 A and  250 B. The first vibration plate  250 A is included as the first unit  200 A, and the second vibration plate  250 B is included as the second unit  200 B. The first vibration plate  250 A has an outer circumferential part fixed to an inner parameter of the yoke  210  and is disposed above the first plate  230 A. An outer circumferential part of the second vibration plate  250 B is fixed to an inner parameter of a second cap  260 B and disposed below the second plate  230 B. 
     The speaker unit  200  includes two caps  260 A and  260 B. A first cap  260 A is included as the first unit  200 A, and the second cap  260 B is included as the second unit  200 B. The first cap  260 A covers the yoke  210 . An inner circumference of a cap  260  may be formed to be greater than the outer circumference of the yoke  210 . The second cap  260 B covers a bottom of a frame  201 . A tuning portion F 1  may be disposed on a top surface of the first cap  260 A. A tuning portion F 2  may be disposed on a bottom surface of the second cap  260 B. Also, a tuning portion F 3  may be disposed on a bottom surface of the yoke  210 . 
     A damper  270  is disposed on the top surface of the first cap  260 A. The damper  270  is disposed along an edge of the first cap  260 A and comes into contact with an inner wall of the cover  300 . 
     A substrate  280  is coupled with the bottom surface of the second cap  260 B, receives an electrical signal from the outside, and transmits the electrical signal to the first voice coil  240 A and the second voice coil  240 B. 
     A rivet  290  passes through and coaxially fastens the yoke  210 , the first magnet  220 A, and the first plate  230 A. A through hole is disposed in a center of each of the yoke  210 , the first magnet  220 A, the first plate  230 A, and the substrate  280 , and the rivet  290  passes through the through hole. 
     The frame  201  is coupled with the yoke  210  and the second cap  260 B. The frame  201  surrounds the first unit  200 A and the second unit  200 B. The frame  201  may be a ring-shaped member including an inner circumferential surface and an outer circumferential surface. The frame  201  includes a tuning hole  202  and a tuning groove  203 . 
     A magnetic field moves to a space between the plates  230 A and  230 B and the yoke  210 . When currents are applied to the voice coils  240 A and  240 B such that the voice coils  240 A and  240 B are magnetized, the voice coils  240 A and  240 B move according to polarities of magnetic forces of the voice coils  240 A and  240 B. That is, when the polarities of the voice coils  240 A and  240 B are equal to polarities of the plates  230 A and  230 B and the yoke  210 , the voice coils  240 A and  240 B are pushed and moved. When the polarities of the voice coils  240 A and  240 B differ from polarities of the plates  230 A and  230 B and the yoke  210 , the voice coils  240 A and  240 B are pulled and moved. As described above, when the voice coils  240 A and  240 B move, the vibration plates  250 A and  250 B generate sounds by vibrating air while moving back and forth. 
       FIG. 6  is a view illustrating the speaker unit including the tuning hole and the tuning portion, and  FIG. 7  is a view illustrating the speaker unit with which the tuning portion is coupled. 
     Referring to  FIGS. 6 and 7 , the frame  201  includes an accommodation groove  204  concavely formed in an outer circumferential surface thereof. The accommodation groove  204  has a plane shape formed by partially cutting the outer circumferential surface of the frame  201 . A top end of the accommodation groove  204  is connected to a top surface  201   a  of the frame  201 . A bottom end of the accommodation groove  204  is a stepped surface. A plurality of such accommodation grooves  204  may be present. The tuning groove  203  is disposed in the accommodation groove  204 . Also, the tuning hole  202  is disposed in the tuning groove  203 . A plurality of such tuning holes  202  may be present. A tuning portion F 4  is mounted in the accommodation groove  204 . The tuning portion F 4  covers the tuning groove  203  and the tuning hole  202 . A shape of the tuning hole  202  may be an oblong shape as shown in the drawing but is not limited thereto and may be a circular shape, an elliptical shape, and the like. Also, a plurality of such tuning holes  202  may be present. The tuning portion F 4  may include a body F 4   a  and a tuning material F 4   b  disposed on the body F 4   a . The body F 4   a  comes into contact with the accommodation groove  204 . A sound which has passed through the tuning material F 4   b  changes in a tone or sound feature. The tuning material F 4   b  may be a mesh material and may include polyester, nylon, nonwoven fabric, a membrane filter, and the like. 
     The tone or sound feature may be minutely adjusted by changing a size and a shape of the tuning hole  202  and a material, density, or the like of the tuning material F 4   b . When a plurality of such speaker units are provided for each size or shape of the tuning hole  202 , an advantage of adjusting a tone feature by only replacing the speaker unit is present. 
       FIG. 8  is a side cross-sectional view of the speaker unit in which a size of the tuning hole and a size of the tuning groove are shown. 
     Referring to  FIG. 8 , a sound pressure level of a low-frequency range according to a change in a diameter D 0  of the tuning hole  202  may be adjusted. Tuning of a sound in a middle-low-frequency range may be performed by adjusting a length L 1  of the tuning hole  202 , a length L 2  of the turning groove  203 , and a distance D 2  between the tuning portion F 4  and the tuning hole  202 . Also, the sound feature may be adjusted according to a change in a diameter D 1  of the tuning material F 4   b.    
       FIG. 9  is a side cross-sectional view of the speaker unit. 
     Referring to  FIG. 9 , a bottom surface of the tuning groove  203  may include a curved surface from an edge of the tuning groove  203  toward the tuning hole  202 . The tuning material F 4   b  is disposed to be aligned with the tuning groove  203 . Also, the tuning material F 4   b  is disposed to be spaced apart from the tuning hole  202 . The tuning hole  202  is disposed along a radial direction of the speaker unit  200 . The tuning hole  202  is formed to pass through an inner circumferential surface and the outer circumferential surface of the frame  201 . 
     The body F 4   a  of the tuning portion F 4  and the inner wall of the cover  300  are spaced apart and form a space. A pipe conduit P 1  is formed between the outer circumferential surface of the frame  201  and the inner wall of the cover  300 . The pipe conduit P 1  communicates with the tuning hole  202  via the tuning groove  203 . Also, the pipe conduit P 1  communicates with the second space portion S 2 . 
       FIG. 10  is a side cross-sectional view of the earphone shown in  FIG. 1 . 
     Referring to  FIG. 10 , a sound generated by moving of the vibration plate  250 A is transmitted to the first space portion S 1 . A part of the sound transmitted to the first space portion S 1  passes through the tuning hole  202 . During this process, the sound is tuned. The sound, which has passed through the tuning hole  202 , passes through the tuning material F 4   b  via the tuning groove  203 . The sound, which has passed through the tuning material F 4   b , is transmitted to the second space portion S 2  through the pipe conduit P 1 . Here, the cover  300  and the housing  100  exclude a hole communicating with the outside. Accordingly, the space formed by the housing  100  and the cover  300  is in a sealed state such that external noise may be blocked and a loss of the sound may be minimized. Also, since a hole is not present in a surface of the earphone, there is provided an advantage of being strong on an external shock. Also, due to high hermeticity, it is possible to prevent foreign substances or water from flowing into the earphone. 
     Although the space formed by the housing  100  and the cover  300  is in the sealed state, air in the first space portion S 1  is transmitted and communicated to the second space portion S 2  through the tuning hole  202 . Accordingly, a phenomenon in which fatigue of a tympanum of a listener which may occur due to the sealed space becomes serious or the listener is deafened is prevented. 
       FIG. 11  is an exploded view of an earphone according to a second embodiment, and  FIG. 12  is a side cross-sectional view of the earphone shown in  FIG. 11 . 
     Referring to  FIGS. 11 and 12 , an earphone  20  according to the second embodiment includes one speaker unit  1200  unlike the earphone  10  according to the first embodiment. 
     The speaker unit  1200  includes a yoke  1210 , magnets  1220 A and  1220 B, a plate  1230 , a voice coil  1240 , a vibration plate  1250 , a cap  1260 , a damper  1270 , a substrate  1280 , and a rivet  1290 . 
     The yoke  1210  is adjacent to the first space portion S 3 . A plurality of holes through which a sound generated by the vibration plate  1250  passes may be arranged in the yoke  1210 . 
     A magnet  1220  may include a third magnet  1220 A and a fourth magnet  1220 B. The third magnet  1220 A and the fourth magnet  1220 B are fixed to a bottom surface of an inside of the yoke  1210 . The third magnet  1220 A may have a cylindrical shape, and the fourth magnet  1220 B may have an annular shape. The fourth magnet  1220 B may be disposed outside the third magnet  1220 A. However, the magnet may include only any one of the third magnet  1220 A and the fourth magnet  1220 B. 
     The plate  1230  is fixed to a top surface of the magnet  1220 . The plate  1230  is fixed further rearward than the magnet  1220 . 
     The voice coil  1240  is fixed to the vibration plate  1250  such that a part of a lower side is disposed between an inner circumference of the yoke  1210  and outer circumferences of the magnet  1220  and the plate  1230 . 
     The vibration plate  1250  has an outer circumferential part fixed to an inner parameter of the yoke  1210  and is disposed above the plate  1230 . 
     The cap  1260  covers the yoke  1210 . An inner circumference of the cap  1260  may be formed to be greater than the outer circumference of the yoke  1210 . The cap  1260  is adjacent to a second space portion S 4 . 
     The damper  1270  is disposed on the top surface of the cap  1260 . The damper  1270  is disposed along an edge of the cap  1260  and comes into contact with an inner wall of the cover  1300 . 
     The substrate  1280  is coupled with a bottom surface of the cap  1260 , receives an electrical signal from the outside, and transmits the electrical signal to the voice coil  1240 . 
     The rivet  1290  passes through and coaxially fastens the yoke  1210 , the magnet  1220 , the plate  1230 , and the substrate  1280  to one another. 
       FIG. 13  is a view illustrating the speaker unit and the tuning portion shown in  FIG. 11 . 
     Referring to  FIG. 13 , a frame  1201  includes an accommodation groove  1204  concavely formed in an outer circumferential surface thereof. The accommodation groove  1204  has a plane shape formed by partially cutting the outer circumferential surface of the frame  1201 . A top end of the accommodation groove  1204  is connected to a top surface  1201   a  of the frame  1201 . A bottom end of the accommodation groove  1204  is a stepped surface. A plurality of such accommodation grooves  1204  may be present. A tuning hole  1202  is disposed in the accommodation groove  1204 . A plurality of such tuning holes  1202  may be present. A tuning portion F 5  is mounted in the accommodation groove  1204 . The tuning portion F 5  covers the tuning hole  1202 . 
     A shape of the tuning hole  1202  may be an oblong shape as shown in the drawing but is not limited thereto and may be a circular shape, an elliptical shape, and the like. A plurality of such tuning holes  1202  may be present. The tuning portion F 5  may include a body F 5   a  and a tuning material F 5   b  disposed on the body F 5   a . The body F 5   a  comes into contact with the accommodation groove  1204 . A sound, which has passed through the tuning material F 5   b , changes in a tone or sound feature. The tuning material F 5   b  may be a mesh material and may include polyester, nylon, nonwoven fabric, a membrane filter, and the like. 
     The tone or sound feature may be minutely adjusted by changing a size and a shape of the tuning hole  1202  and a material, density, or the like of the tuning material F 5   b . When a plurality of such speaker units are provided for each size or shape of the tuning hole  1202 , an advantage of adjusting a tone feature by only replacing the speaker unit is present. 
       FIG. 14  is a side cross-sectional view of the speaker unit shown in  FIG. 11 . 
     Referring to  FIG. 14 , the tuning material F 5   b  is aligned with the tuning hole  1202 . The tuning hole  1202  is disposed along a radial direction of the speaker unit. The tuning hole  1202  is formed to pass through an inner circumferential surface and the outer circumferential surface of the frame  1201 . 
     The body F 5   a  of the tuning portion F 5  and an inner wall of the cover  1300  are spaced apart and form a space. A pipe conduit P 2  is formed between the outer circumferential surface of the frame  1201  and the inner wall of the cover  1300 . The pipe conduit P 2  communicates with the tuning hole  1202 . Also, the pipe conduit P 2  communicates with the second space portion S 2 . 
       FIG. 15  is a side cross-sectional view of the earphone shown in  FIG. 11 . 
     Referring to  FIG. 15 , a sound generated by moving of the vibration plate  1250  is transmitted to a first space portion S 3 . A part of the sound transmitted to the first space portion S 3  passes through the tuning hole  1202 . During this process, the sound is tuned. The sound which has passed through the tuning hole  1202  passes through the tuning material F 5   b . The sound which has passed through the tuning material F 5   b  is transmitted to the second space portion S 4  through the pipe conduit P 2 . 
       FIG. 16  is an exploded view of an earphone according to a third embodiment,  FIG. 17  is a side cross-sectional view of the earphone shown in  FIG. 16 , and  FIG. 18  is an exploded view of a speaker unit shown in  FIG. 16 . 
     Referring to  FIGS. 16 to 18 , an earphone  30  according to the third embodiment includes one speaker unit  2200  unlike the earphone  10  according to the first embodiment while a vibration plate  2250  is located on a cover  2300 . 
     The speaker unit  2200  may include a frame  2201 , a yoke  2210 , fifth and sixth magnets  2220 A and  2220 B, a plate  2230 , a voice coil  2240 , the vibration plate  2250 , and a substrate  2280 . 
     A plurality of holes through which a sound generated by the vibration plate  2250  passes may be arranged in the yoke  2210 . 
     A magnet  2220  may include the fifth magnet  2220 A and the sixth magnet  2220 B. Each of the fifth magnet  2220 A and the sixth magnet  2220 B is fixed to the yoke  2210 . The fifth magnet  2220 A may have a cylindrical shape, and the sixth magnet  2220 B may have an annular shape. The sixth magnet  2220 B may be disposed outside the fifth magnet  2220 A. 
     The plate  2230  is fixed to one surface of the magnet  2220 . The plate  2230  is disposed further forward than the magnet  2220 . 
     The voice coil  2240  is fixed to the vibration plate  2250  such that a part of a lower side is disposed between an outer circumference of the fifth magnet  2220 A and an inner circumference of the sixth magnet  2220 B. 
     The vibration plate  2250  has an outer circumferential part fixed to an inner parameter of the frame  2201  and is disposed above the plate  2230 . 
     The substrate  2280  is coupled with a bottom surface of the frame  2201 , receives an electrical signal from the outside, and transmits the electrical signal to the voice coil  2240 . 
     A tuning portion F 6  may be disposed on a side surface of the frame  2201 . A tuning portion F 7  having an arc shape may be disposed on the bottom surface of the frame  2201 . 
     A plurality of circular tuning portions F 8  may be arranged on the yoke  2210 . 
       FIG. 19  is a view illustrating the speaker unit and the tuning portion shown in  FIG. 18 . 
     Referring to  FIG. 19 , the frame  2201  may include a protruding portion  2203  convexly protruding from an outer circumferential surface thereof. The protruding portion  2203  includes an accommodation groove  2204  which concavely formed. A tuning hole  2202  is disposed in the accommodation groove  2204 . The tuning portion F 6  is mounted in the accommodation groove  2204 . The tuning portion F 6  covers the tuning hole  2202 . 
     A shape of the tuning hole  2202  may be an oblong shape as shown in the drawing but is not limited thereto and may be a circular shape, an elliptical shape, and the like. A plurality of such tuning holes  2202  may be present. The tuning portion F 6  may include a body F 6   a  and a tuning material F 6   b  disposed on the body F 6   a . The body F 6   a  comes into contact with the accommodation groove  2204 . A sound which has passed through the tuning material F 6   b  changes in a tone or sound feature. The tuning material F 6   b  may be a mesh material and may include polyester, nylon, nonwoven fabric, a membrane filter, and the like. 
     The tone or sound feature may be minutely adjusted by changing a size and a shape of the tuning hole  2202  and a material, density, or the like of the tuning material F 6   b . When a plurality of such speaker units are provided for each size or shape of the tuning hole  2202 , an advantage of adjusting a tone feature by only replacing the speaker unit is present. 
       FIG. 20  is a side cross-sectional view of the earphone shown in  FIG. 16 . 
     Referring to  FIG. 20 , the tuning material F 6   b  is aligned with the tuning hole  2202 . The tuning hole  2202  is disposed along a radial direction of the speaker unit  2200 . The tuning hole  2202  is formed to pass through an inner circumferential surface and the outer circumferential surface of the frame  2201 . 
     The body F 6   a  of the tuning portion F 6  and an inner wall of the cover  2300  are spaced apart and form a space. A pipe conduit P 3  is formed between the outer circumferential surface of the frame  2201  and the inner wall of the cover  2300 . The pipe conduit P 3  communicates with the tuning hole  2202 . Also, the pipe conduit P 3  communicates with a sixth space portion S 6 . 
     A fifth space portion S 5  means a space disposed in front of the speaker unit  2200 . In detail, the fifth space portion S 5  means a space surrounded by inner surfaces of the speaker unit  2200  and the cover  2300  while the speaker unit  2200  is accommodated in a housing  2100  and the cover  2300 . The sixth space portion S 6  means a space disposed in the rear of the speaker unit  2200 . In detail, the sixth space portion S 6  means a space surrounded by inner surfaces of the speaker unit  2200  and the housing  2100  while the speaker unit  2200  is accommodated in the housing  2100  and the cover  2300 . 
     A sound generated by moving of the vibration plate  2250  is transmitted to the fifth space portion S 5 . A part of the sound transmitted to the fifth space portion S 5  passes through the tuning hole  2202 . During this process, the sound is tuned. The sound which has passed through the tuning hole  2202  passes through the tuning portion F 6 . The sound which has passed through the tuning portion F 6  is transmitted to the sixth space portion S 6  through the pipe conduit P 3 . 
     According to the embodiment, there is provided an advantageous effect of fundamentally eliminating a tuning hole, which is externally exposed, by forming a tuning hole in a frame of a speaker unit. 
     According to the embodiment, there is provided an advantageous effect of preventing water or foreign substances from flowing into a housing of an earphone. 
     According to the embodiment, there is provided an advantageous effect of minutely adjusting a sound by replacing speaker units having different sized through holes. 
     According to the embodiment, since a hole is not present in a surface of the earphone, there is provided an advantage of being strong on an external shock. 
     According to the embodiment, there is provided an advantageous effect of preventing a phenomenon in which fatigue of a tympanum of a listener becomes serious or the listener is deafened. 
     As described above, an earphone in which a tuning means is provided in a speaker unit according to one exemplary embodiment of the present invention has been described in detail. 
     It should be noted that the above-described one embodiment of the present invention is merely an example in all aspects and is not intended to be limitative, and the scope of the present invention will be defined by the following claims rather than the above detailed description. Also, it should be construed that all changeable or modifiable shapes derived from the meaning and scope of the claims and equivalents thereof are included in the scope of the present invention.