Speaker apparatus

According to an aspect of the invention, there is provided a speaker apparatus including: a speaker frame; and a connection terminal for electrically connecting to an outside of a speaker, an axis line of the connection terminal being arranged along a tangential line direction of a circumference of the speaker, the connection terminal being not projected to an outer side in a diameter direction of the speaker from the speaker frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority from the prior Japanese Patent Application No. 2005-333339, filed on Nov. 17, 2005; the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a speaker apparatus.

2. Related Art

FIG. 1shows a constitution of a general dynamic related-art speaker apparatus.

The speaker apparatus1includes; a magnetic circuit3, a frame5attached with the magnetic circuit3at a rear portion thereof, a vibrating plate9of a cone-like shape in which an edge7in a roll-like shape at an outer periphery thereof is fixed to a vibrating plate supporting portion5aof a front portion of the frame5, and a voice coil12wound around a voice coil bobbin11in a cylindrical shape.

The magnetic circuit3includes a yoke15having a structure of projecting a center pole15bin a cylindrical shape at a center of a plate15ain a shape of a circular plate, a magnet16in a ring-like shape fitted to an outer periphery of the center pole15b, and a top plate17in a ring-like shape fitted to be mounted to a front end side of the center pole15bto interpose the magnet16between the top plate17and the plate15a.

A gap between an inner periphery of the top plate17and the center pole15bserves as a magnetic gap19for arranging the voice coil12.

The vibrating plate9is formed with an opening portion9afor inserting the voice coil bobbin11at a center thereof. The edge7bonded to an outer peripheral edge of the vibrating plate9is fixed to the vibrating plate supporting portion5a. An attaching flange7amounted to an outer periphery of the edge7is interposed between a gasket21in a ring-like shape pasted to the vibrating plate supporting portion5aand the vibrating plate supporting portion5a.

Further, an inner peripheral portion9bof the vibrating plate9forming the opening portion9ais fixed to an outer periphery of the voice coil bobbin11inserted to the opening portion9aby adhering or the like.

Further, a center portion of the vibrating plate9is pasted with a dust cap28. The dust cap28covers a front side of the voice coil bobbin11to prevent dust and dirt from invading the magnetic gap19.

The voice coil bobbin11in the cylindrical shape is fitted to an outer periphery of the center pole15bmovably in an axial direction and is elastically supported by the frame5via a damper25to restrict movement thereof in the axial direction.

Normally, the damper25forms a bellows structure concentrically with the voice coil bobbin11.

The damper25damps the vibrating plate9by restricting displacement of the voice coil bobbin11in a radius direction by fixing an outer peripheral edge thereof to a damper supporting portion5bof the frame5and fixing an inner peripheral portion thereof to an outer periphery of the voice coil bobbin11and absorbing vibration energy by deforming the bellows in driving the vibrating plate9.

The frame5includes a plurality of frame openings5cformed at predetermined intervals along a circumferential direction of the speaker between the vibrating plate supporting portion5aand the damper supporting portion5b. The frame opening5cserves as a vent hole for escaping an air flow produced by a back pressure in driving the vibrating plate9.

Further, the frame opening5cnot only serves as the above-described vent hole but also makes the frame light-weighted

The related-art speaker apparatus1vibrates the vibrating plate9by a reciprocating vibration of the voice coil bobbin11when a voice signal is inputted to the voice coil12by 2 pieces of positive and negative connection cables8,8from an amplifier and a pair of input terminals4,4for connecting the connection cables, tinsel wires, not illustrated, whereby sound is reproduced.

According to the connection terminals4,4, front ends of the connection cables8,8are inserted into connection openings penetrated by pushing front ends thereof in an arrow mark direction and the front ends are released from being pressed to thereby finish connection.

Meanwhile, in connecting the connection cables8,8to the speaker apparatus1, the illustrated push type connection-terminals4,4are preferred since a connecting tool or other part is not needed, an allowable range of a thickness of the connection cables8,8is wide, and the connection terminals4,4are excellent (refer to, for example, JP-UM-A-58-65767).

Meanwhile, recently, there is increased an example for using a speaker apparatus having a large aperture of a sub woofer or the like for reproducing heavy low sound also in a vehicle-mounted audio system.

When the related-art speaker apparatus having a large aperture is designed for vehicle-mounted use, a depth dimension of a portion utilized as a cabinet of the speaker apparatus such as a vehicle-mounted speaker cabinet or an inner side of a vehicle door is limited and therefore, it is a problem to thin the speaker apparatus.

However, according to the related-art speaker apparatus1in which the voice coil bobbin11is elastically supported by the damper25as described above, a space of arranging the damper25needs to provide between the vibrating plate9and the magnetic circuit3. So, it is difficult to shorten a dimension in the axial direction of the speaker apparatus in order to provide the space of installing the damper25. Therefore, it is difficult to thin thinning the speaker apparatus.

Further, a stiffness of the damper25is normally larger than that of the edge7and therefore, mechanical fatigue by a long period of time of use is brought about earlier than in the edge7and there is a concern of causing a failure by deteriorating a control function.

Further, particular vibration or abrazing sound is generated by deforming the bellows in propagating vibration between the contiguous bellows on the damper The particular vibration and abrazing sound conversely effect an influence on the vibration of the voice coil12or the vibrating plate9to deteriorate sound quality. Proposals are made for the problems (refer to, for example, JP-A-2005-191746).

SUMMARY

When the above-described connection terminals capable of dealing with comparatively bold connection cables are adopted and the connection cables8,8which are bold and difficult to bend are used, a comparatively large wiring space is needed. However, there is not an allowance in a depth dimension of an inner side of a speaker cabinet or an inner side of a vehicle door for attaching a thinned speaker apparatus. A space of a back face of the attached speaker apparatus is narrowed and it is difficult to ensure a space of leading out the connection cables8,8.

An operation of the connection cable may be extremely simple and firm by, for example, inserting the front end portion of the cord into the opening by pressing one end of the connection terminal to release the front end portion from being pressed. However, by thus configuration, this type connection cable is generally large in its size. Therefore, it is difficult to be applied to a thinned type speaker apparatus.

The present invention has been made in view of the above circumstances and provides a speaker apparatus. According to an aspect of the invention, the connection terminal and the connection cable may not be protruded from the speaker frame, even though the comparatively bold connection cable is used in the comparative connection terminal.

According to another aspect of the invention, there is provided a speaker apparatus including: a speaker frame; and a connection terminal for electrically connecting to an outside of a speaker, an axis line of the connection terminal being arranged along a tangential line direction of a circumference of the speaker, the connection terminal being not projected to an outer side in a diameter direction of the speaker from the speaker frame.

DESCRIPTION OF THE EMBODIMENTS

Embodiments will be explained in details with reference to the drawings as follows.

First Embodiment

As shown byFIG. 2,FIG. 3,FIG. 4andFIG. 5, a speaker apparatus30according to a first embodiment of the invention has a substantially concentric shape centering on a speaker center line-37. The speaker apparatus30includes: a magnetic circuit33; a speaker frame35attached with the magnetic circuit33at a rear portion thereof; a vibrating plate41and a drive member42(hereinafter, referred to as drive cone) coaxially arranged in a direction of driving the speaker, and a voice coil46wound around a voice coil bobbin45in a cylindrical shape.

The magnetic circuit33includes a yoke51having a structure of projecting a center pole51bin a cylindrical shape at a center of a plate51ain a shape of a circular plate, a magnet53in a ring-like shape fitted to an outer periphery of the center pole51b, and a top plate55in a ring-like shape fitted to a front end side of the center pole51bto interpose the magnet53between the top plate55and the plate51a. A gap between an inner periphery of the top plate55and the center pole51bforms a magnetic gap57of arranging the voice coil46.

The speaker frame35has a shape of a bowl having a shallow bottom and an inner face of a bottom plate portion35ais pertinently attached with the magnetic circuit33in a state of mounting the plate51aof the yoke51. The speaker frame35is separately provided with a positive terminal31(hereinafter, referred to as “an anode connection terminal31”) and a negative terminal31(hereinafter, referred to as “cathode connection terminal31”) which are positioned so as to interpose the magnetic circuit33therebetween. The magnetic circuit33and the connection terminals31,31are thinned type which is arranged to substantially align in a speaker plane direction.

According to the first embodiment, the connection terminals31,31electrically connected to outside of the speaker of, for example, an amplifier or the like are constituted such that axis lines C thereof are arranged along tangential line directions of a circumference of the speaker and are not projected to an outer side in a diameter direction of the speaker from the speaker frame35.

Even when the speaker apparatus30is thinned, that is, even when the speaker frame35is flat, the speaker apparatus30can be thinner without projecting the connection terminals31,31to a back face side of the speaker.

When the axis lines C of the connection terminals31,31are arranged in a circumferential direction (horizontal direction) of the speaker, a diameter of the connection terminals31,31can be bold and its length can be long, so that the connection terminals31,31can be large-sized. Bold wires can be used for the connection cables8,8. an acoustic function can be maintained.

According to the first embodiment, the connection terminals31,31are configured by arranging the cathode and the anode substantially on opposite sides by interposing a center of the speaker. The arrangement of the connection terminals31,31is not concentrated on one portion but dispersed to two portions to facilitate to constitute the connection terminals31,31by a large size.

As for an outer diameter dimension of the connection terminals31,31, the connection terminals31,31having, for example, a skin film outer diameter of 6 mm (about 4 mm of an outer diameter without a skin) may be used.

According to the first embodiment, the connection terminals31,31provided at recess portions32of the speaker frame35so as not to project from the speaker frame35to the side of back face of the speaker.

The speaker frame35is respectively provided with a vibrating plate supporting portion35cof the vibrating plate41and a vibrating plate supporting portion35dof the drive cone42which are apart from each other along the direction of driving the speaker.

A peripheral wall35bbetween the two vibrating plate supporting portions35c,35dis constituted by a hermetically closed wall in which openings are not provided. The vibrating plate supporting portions35c,35dand the bottom plate portion35afor holding the magnetic circuit33are pertinently connected by a connecting portion23. The connecting portion23is constituted to form a plurality of openings35fat predetermined intervals along a circumferential direction of the speaker. A back face of the vibrating plate supporting portion35cof the speaker frame35serves as a flange face hermetically fixed to a baffle71of a speaker cabinet.

The vibrating plate41and the drive cone42are a cone-type vibrating plates, edges61,62constituting outer peripheral portions thereof are fixed to the vibrating plate supporting portions35c,35don the speaker frame35, and inner peripheral portions41b,42bthereof are bonded to be fixed to the voice coil bobbin45.

A member of a material having high internal loss for the edges61,62may be used in order to attenuate vibration propagated from cone paper constituting a main body of the vibrating plate. Therefore, the edges61,62may be constituted by bonding, for example, members of a material different from that of cone paper (material having-inner loss higher than that of cone paper).

According to the vibrating plate41arranged on a front face side of the speaker apparatus30, a diameter of an opening of a center portion thereof is set to be larger than a diameter of an opening of the drive cone42arranged on the front face side of the speaker apparatus30, and the edge61is provided with a bulged portion61abulged to an outer side of a hermetically closed space67between the vibrating plates (front face side of the speaker apparatus).

Further, according to the drive cone42arranged at a back portion of the vibrating plate41, the diameter of the opening of the center portion is set to be substantially equal to an outer diameter of the voice coil bobbin45, and the edge62is provided with a bulged portion62abulged to an outer side of the hermetically closed space67between the vibrating plates (back face side of the speaker apparatus). Further, directions of recesses and projections of the bulged portion61aand the bulged portion62aare not limited to directions as shown byFIG. 5.

The respective edges61,62of the vibrating plate41and the drive cone42are respectively fixed to the two vibrating plate supporting portions35c,35dof the speaker frame35mentioned above.

Further, according to the edge61of the vibrating plate41, an attaching flange portion61bcontinuously provided to an outer peripheral portion thereof is pinched by a gasket65and the vibrating plate supporting portion35cto be fixed to the vibrating plate supporting portion35c.

Further, the inner peripheral portion41bof the vibrating plate41is bonded to the drive cone42in a state of being overlapped on the drive cone42disposed on a back side thereof.

Further, a dust cap28is pasted to be mounted to a center portion of the vibrating plate41. The dust cap28covers a front side of the voice coil bobbin45to prevent dust and dirt or the like from invading the magnetic gap57.

Further, there is constituted a structure of bonding the inner peripheral portions41b,42bof the vibrating plate41and the drive cone42to be fixed to the voice coil bobbin45by adhering to fix the inner peripheral portion42bof the drive cone42to an outer periphery of the voice coil bobbin45by a pertinent adhesive.

The voice coil bobbin45in the cylindrical shape is fitted to an outer periphery of the center pole51bmovably in an axial direction and is positioned in a radius direction and in the axial direction by the drive cone42bonded to an outer periphery thereof.

In the case of the embodiment, the space67between the vibrating plates surrounded by the vibrating plate41and the drive cone42and the speaker frame35is hermetically closed.

When the vibrating plate41and the drive cone42are driven by displacing the voice coil bobbin45in the axial direction, as shown byFIG. 5, a gas of air or the like sealed in the hermetically closed space67between the vibrating plates is compressed by displacing the vibrating plate41and the drive cone42and displacing the edges61a,62ato achieve spring performance as an air spring, and the voice coil bobbin45is controllably supported.

According to the first embodiment, a damper for elastically supporting the voice coil bobbin45is not mounted on the back side of the vibrating plate41and the drive cone42, and a thinned one of the speaker apparatus30used in a vehicle-mounted audio system or the like can be realized by shortening a dimension in the axial direction of the speaker apparatus by omitting a damper and a space of installing the damper.

The above-described connection terminals31,31will be explained in details.

According to the connection terminal31, as shown byFIG. 4, the connection terminals31,31are push type including inner shafts31ahaving holes31cfor inserting the connection cables8,8and operating portions31bwhich are slid by covering the inner shafts31aand having outer holes31dcommunicatable with the holes31c.

According to the inner shafts31aand the operating portions31b, for example, the operating portion31bis held movably along the axis line C by fitting a long hole31eformed at the operating portion31band a guide projection31fprojected from the inner shaft31aand is urged in a direction of a front end of the connection terminal (arrow mark F1direction ofFIG. 4) by a spring member, not illustrated, inwardly mounted to an inner side of the operating portions31b.

The connection terminals31,31, differentiates the anode and the cathode, for example, front end faces31gthereof are pasted with stickers having different colors. According to the configuration, not only parts of the connection terminals can be made common but also a failure in differentiating a display of a polarity can be avoided in integrating the connection terminal.

Therefore, by an operation of pushing the operating portion31b(operation in a direction of an arrow mark F2), the operating portion31bis moved relative to the inner shaft31aand an opening of communicating the hole31cand the outer holes31dis formed. A front end portion of the connection cable8is inserted into the opening (arrow mark F3direction), and the front end of the connection cable8is bit to be held by the hole31cand the outer hole31dby an urge force of the spring member by releasing the pushing operation. The cable can be connected by such an extremely simple operation.

According to the first embodiment, as shown byFIG. 5andFIG. 6, outer peripheral sides of the speaker of the connection terminals31,31are provided with locking walls38for preventing the front ends of the connection cables8,8from being extruded to the outer peripheral sides of the speaker at positions opposed to the holes31c. The locking wall38is constituted as an outer wall of the recess portion32. According to the constitution, when the connection cable8is inserted, the front end can firmly be stopped at a predetermined position, a state of considerably extruding the front end of the connection cable8from the connection terminal31is avoided and, for example, the connection cable8can be prevented from being shortcircuited or the like.

According to the embodiment, there is provided a guide mark71for guiding a direction of inserting the connection cable8. As the guide mark71, for example, an arrow mark, a triangular mark or the like directed in a direction of the hole31ccan be used.

Further, the guide mark71is provided at the recess portion32or a vicinity thereof as a mark showing a direction directed to the hole31c.

Further, according to the first embodiment, the guide mark71is formed at an inclined wall face39for guiding the front end of the connection cable8in inserting the connection cable8. According to the constitution, when the connection cable8is inserted into the hole31c, a direction of inserting the connection cable8or an operation of connecting the connection cable8to a position is guided by the guide mark71, further, by enabling to utilize the inclined wall face39as a guide wall face such that the cord front end portion is slid along the inclined wall face39, an operability in inserting the connection cable8can be promoted.

Further, the inclined wall face39is provided with an inclination of substantially 45 degrees as an angle of inclination β in an axial direction of the speaker relative to the speaker center line37. Further, although the angle of inclination β can be set to an arbitrary angle, the angle of inclination can be set to, for example, an angle of inclination of 0 degree through 90 degrees. Further, it is preferable to form the direction of the hole31cand the outer hole31dsuch that the connection cables31,31are directed to a skewed inner side along the back face of the speaker. By the constitution, the connection cables31,31can be led out skewedly to the inner side of the back face of the speaker, and can be wired to be laid along the back face of the speaker and therefore, when there is a clearance to a degree of the thickness of the connection cables31,31, the speaker apparatus30can be installed to a space which is not provided with an allowance in a direction of the back face.

According to the first embodiment, the recess portion32includes faces of enabling to bring the thumb to sides of front end faces31gof the connection terminals31,31and providing outer wall faces32asubstantially in parallel with the front end faces31gcapable of bringing the forefinger thereto on an outer side of a connection base portion of the recess portion32.

Therefore, a dimension W1between the front end face31gand the outer wall face32ais set to, for example, about 40 mm. Further, an interval W2between the front end face31gand a wall portion32bopposed to the front end face31gis set to about 13 mm as a dimension of bringing the thumb of a comparatively big person thereto. Therefore, as shown byFIG. 7, a barrel portion of the thumb can press the connection terminal31while being brought into contact with the recess portion32or a frame portion therebelow.

According to the constitution, as shown byFIG. 7, in connecting the connection cable8, by pushing the front end face31gof the connection terminal31by the thumb80and touching to support a side face of the forefinger81to the outer peripheral wall32a, the hole31cand the outer hole31dare communicated, and by inserting the front end of the connection cable8to the communicated opening and releasing the thumb80and the forefinger81from being pressed, the connection cable8can be bit by the opening. That is, a connection operability in connecting the connection cable8to the speaker apparatus1is extremely excellent.

Second Embodiment

FIG. 8is a perspective view of a speaker apparatus according to a second embodiment.

According to a speaker apparatus40of the second embodiment, a basic constitution thereof is the same as that of the speaker apparatus30of the first embodiment, the same constituent portions are attached with the same notations and an explanation thereof will be omitted.

The second embodiment shown inFIG. 8differs from the first embodiment by connecting the connection cables8,8from a side of a side face of the speaker. That is, according to the connection terminal31, the hole31cand the outer hole31dare disposed on the side of the side face of the speaker and the connection cables8,8are inserted from an outer side of the side of the side face of the speaker by the first embodiment which is not provided with the locking wall38.

Therefore, the connection cables8,8are not led out from the back face side of the speaker in the case of Example 1 but are led out from the side of the side face of the speaker as shown byFIG. 8. The case is suitable for a case in which a space in a thickness direction of the speaker is smaller than that in the case of the first embodiment and there is a comparatively large allowance in a space on the side of the side face of the speaker in a space of arranging the speaker apparatus40.

The constitution of the connection terminal is not limited to the above-embodiments and can pertinently be changed in accordance with the scope of the invention. For example, instead of the connection terminal of the push type, a screw type one of attaching the connection cable by screwing a screw will do.

As has been described in details, the speaker apparatus30(40) is constituted such that the connection terminals31,31for electrically connecting to outside of the speaker are provided, the connection terminals31,31are arranged such that the axis lines C are in line with the tangential direction of the circumference of the speaker, and are not projected to the outer side in the diameter direction of the speaker from the speaker frame35.

Thereby, even when the speaker apparatus30(40) is thinned, that is, even when the speaker frame35is constructed by the flat constitution, the connection terminals31,31are not projected to the back face side of the speaker and thinned formation of the speaker apparatus30(40) is not hampered. Further, the axial lines C of the connection terminals31,31are arranged in the circumferential direction (horizontal direction) of the speaker and therefore, it is easy to constitute a large size for making the diameter of the connection terminals31,31thick and for prolonging the connection terminals31,31, as a result, the thick wire can be used for the connection cable, and it is easy to adopt the constitution which is easy to maintain the acoustic function.

According to the embodiments, even when the speaker is thinned, that is, even when the speaker frame is constituted to be flat, the connection terminal is not projected to the back face side of the speaker and thinned formation of the speaker is not hampered.

Further, since the axis line of the connection terminal is arranged in a circumferential direction (horizontal direction) of the speaker, it is easy to make the connection terminal large-sized making a diameter of the connection terminal bold and prolonging the connection terminal, as a result, a bold wire can be used for the connection cable and it is facilitated to adopt a constitution which is easy to maintain an acoustic function.

According to the embodiments, there can be adopted a constitution in which a cathode and an anode of the connection terminals are arranged substantially on opposed sides interposing a center of the speaker. According to the constitution, arrangement of the connection terminals is not concentrated to one portion but can be dispersed to two portions, and a comparatively large one of the connection terminal can be provided.

According to the embodiments, there is constructed a constitution in which the connection terminal is provided at a recess portion of the speaker frame so as not to be projected from the speaker frame on a back face side of the speaker.

According to the embodiments, the connection terminal may be formed such that a connection cable connected thereto is directed to a skewed-inner side along a back face of the speaker. Further, it is preferable that a wall face inclined by substantially 45 degrees for guiding a front end of the connection cable in inserting the connection cable. According to the constitution, the connection cable can be led out skewedly to an inner side of the back face of the speaker, and can be wired to be laid along the back face of the speaker and therefore, when there is a clearance to a degree of a thickness of the connection cable, the speaker apparatus can be installed in a space which is not provided with an allowance in the direction of the back face.

According to the embodiments, the connection terminal can adopt a push type constitution including an inner shaft having a hole for inserting to connect the connection cable and an operating portion sliding to cover the inner shaft and having an outer hole communicatable with the hole. Further, it is preferable that directions of the hole and the outer hole are formed such that the connection cable is directed to the skewed inner side along the back face of the speaker. According to the constitution, the cable can be connected by a simple operation of inserting the connection cable into the hole by an operation of pushing the operating portion.

According to the embodiments, there can be adopted a constitution in which an outer peripheral side of the speaker of the connection terminal is provided with a locking wall for preventing the front end of the connection cable connected to the connection terminal from being extruded to the outer peripheral side of the speaker. According to such a constitution, when the connection cable is inserted thereinto, the front end is firmly stopped at a predetermined position and therefore, firm connection is guaranteed, further, the front end of the connection cable can be prevented from being extruded from the connection terminal, and the connection cable can be prevented from being shortcircuited. Further, it is possible that the locking wall is provided to constitute an outer wall of the recess portion.

According to the embodiments, a guide mark for guiding a direction of inserting the connection cable is provided. Further, according to the embodiments, it can be constituted that the guide mark is an arrow mark directed in the direction of the hole. There can be constructed a constitution in which the guide mark is constituted by substantially an arrow mark directed to the hole and is provided at the recess portion or a vicinity thereof.

According to the constitution, a direction of inserting the connection cable and the operation of connecting a position thereof are guided by the guide mark and handling of the operation is extremely facilitated.

Further, according to the embodiments, a portion formed with the guide mark can be constituted at the inclined wall face for guiding the front end in inserting the connection cable. According to the constitution, when the connection cable is inserted into the hole, the wall face can be utilized as a guide wall such that a cord front end portion thereof is slid along the inclined wall face, and an operation of attaching the connection cable can be promoted. Further, the inclined wall face functions as the guide wall face in a direction of a wire of the connection cable after connection.

According to the embodiments, the recess portion includes a space for enabling to bring the thumb to a side of a front end face of the connection terminal, and an outer side of a connection base portion of the recess portion is provided with an outer wall face to which the forefinger can be touched. According to the constitution, there can be carried out an operation of pushing the front end of the connection terminal by pinching the front end and the outer wall face of the connection terminal by the fingers, for example, when the connection terminal is constructed by a constitution of the above-described push type, an operability of connecting the connection cable can be improved.

According to the embodiments, the speaker apparatus can be applied to a thin type speaker arranged with the magnetic circuit and the connection terminal to a substantially align in a speaker plane direction. According to the constitution, by constructing the connection terminal by a constitution of being extended in the speaker plane direction, thinned formation of the speaker can further be promoted.

The embodiments are applicable to a speaker apparatus including a vibrating plate and a drive member arranged coaxially with each other along a direction of driving the magnetic circuit. Outer peripheral portions of the vibrating plate and the drive member are fixed to vibrating plate supporting portions on the frame, inner peripheral portions of the vibrating plate and the drive member are bonded to be fixed to a voice coil bobbin, a space surrounded by the vibrating plate and the drive member and the frame are hermetically closed, and a vibrating system is supported by the voice coil bobbin by a spring performance of gas at inside of the space.