Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2004297318 An electro-acoustic electro-acoustic transducer which prevents excessive deformation of a diaphragm due to wind pressure even when the diaphragm is formed of a thin film. In the electrodynamic electroacoustic transducer 10 in which the film thickness of the diaphragm 12 is set to a value of 15 μm or less, a diaphragm stopper 30 is provided as a deformation preventing structure on the upper surface of the central portion of the yoke 26. Then, when the diaphragm 12 is deformed by a predetermined amount or more beyond the maximum amplitude at the time of ringing, the diaphragm 12 is made to abut on the inner peripheral side portion 12A positioned on the inner peripheral side of the voice coil 16. When the foldable portable communication device on which the electroacoustic transducer 10 is mounted is folded, wind pressure acts on the diaphragm 12 through the sound release hole 20 a formed in the cover 20, but the diaphragm stopper 30 Prevents the diaphragm 12 from being deformed excessively. [Selected figure] Figure 1 Electro-acoustic transducer TECHNICAL FIELD [0001] The present invention relates to a so-called electrodynamic electroacoustic transducer. In general, an electrodynamic electroacoustic transducer comprises a diaphragm, a voice coil having a front end fixed to the diaphragm, and a cylindrical magnetic gap for accommodating the rear end of the voice coil. And a magnetic circuit unit formed. At that time, as described in, for example, Patent Document 1, in many electroacoustic transducers, a cover is provided to cover the diaphragm from the front side in order to protect the diaphragm. A sound emission hole is formed in the cover for radiating the sound from the diaphragm forward. [Patent Document 1] Japanese Patent Application Laid-Open No. 11-146487 SUMMARY OF THE INVENTION In recent years, the size of the liquid crystal screen has been increased in portable communication devices such as portable telephones. It has been demanded that the electro- 12-05-2019 1 acoustic transducer to be mounted be miniaturized. However, when the electroacoustic transducer is miniaturized, its lowest resonance frequency rises, and it becomes impossible to obtain the desired frequency characteristics. On the other hand, if the thickness of the diaphragm is reduced and set to a value of 15 μm or less, it is possible to effectively suppress the increase in the lowest resonance frequency. However, when the diaphragm is formed of a thin film as described above, the following problems occur. That is, in a foldable portable communication device, when it is folded, a large wind pressure acts on the diaphragm through the sound output hole of the cover of the electroacoustic transducer, but at this time the diaphragm is a thin film If configured, there is a problem that the diaphragm is excessively deformed by the wind pressure. And, if the diaphragm is deformed in this way, there is a problem that the acoustic characteristics set at the time of manufacture may be disturbed. The present invention has been made in view of such circumstances, and in the electrodynamic electroacoustic transducer, even when the diaphragm is formed of a thin film, the diaphragm is excessively deformed by wind pressure. It is an object of the present invention to provide an electro-acoustic transducer which can prevent in advance. SUMMARY OF THE INVENTION The present invention achieves the above object by providing a predetermined deformation preventing structure. That is, in the electro-acoustic transducer according to the present invention, a diaphragm, a voice coil whose front end is fixed to the diaphragm, and a magnetic magnetic tube in which a cylindrical magnetic gap for accommodating the rear end of the voice coil is formed. A circuit unit and a cover provided so as to cover the diaphragm from the front side and having a sound emission hole formed for radiating the sound from the diaphragm forward, the film thickness of the diaphragm In the electro-acoustic transducer in which the value is set to a value of 15 .mu.m or less, the diaphragm is excessively deformed by the wind pressure acting on the diaphragm through the sound release hole in at least one of the diaphragm, the magnetic circuit unit and the cover. It is characterized in that a deformation preventing structure is provided to prevent the problem. The sound output hole may be single or plural. The deformation preventing structure is not particularly limited in its specific configuration, as long as the diaphragm can be prevented from being excessively deformed by the wind pressure acting on the diaphragm through the sound output hole of the cover. It is not limited. The term excessively deform means to deform so large that it can not immediately return to the original diaphragm shape beyond the maximum amplitude at the time of ringing. As shown in the above configuration, the electro-acoustic transducer according to the present invention comprises a diaphragm, a voice coil having a front end fixed to the diaphragm, and a rear end of the voice coil. A magnetic circuit unit in which a cylindrical magnetic gap to be accommodated is formed, and a cover provided so as to cover the diaphragm from the front side and having a sound emission hole for radiating sound from the diaphragm forward The film thickness of the diaphragm is set to a value of 15 μm or less, but at least one of the diaphragm, the magnetic circuit unit and the cover is affected by wind pressure acting on the diaphragm through the sound release hole. Since the deformation preventing structure is provided to prevent excessive deformation, the following effects can be 12-05-2019 2 obtained. That is, in a foldable portable communication device equipped with the electro-acoustic transducer according to the present invention, when it is folded after use, the electro-acoustic transducer has a large diaphragm through the sound output hole. Although wind pressure acts, since the electro-acoustic transducer is provided with a deformation preventing structure, this wind pressure can prevent the diaphragm from being excessively deformed. As described above, according to the present invention, in the electrodynamic electroacoustic transducer, even when the diaphragm is formed of a thin film, excessive deformation of the diaphragm due to wind pressure is prevented in advance. Can. And thereby, it is possible to eliminate the possibility that the acoustic characteristics set at the time of manufacture may be disturbed. By the way, most of the electro-acoustic transducers mounted on the portable communication device have an inner peripheral side portion located on the inner peripheral side of the voice coil in the diaphragm formed in a substantially convex spherical shape. The inner circumferential portion is easily deformed into a substantially concave spherical shape by wind pressure. Therefore, in the above configuration, when the diaphragm is deformed by a predetermined amount or more beyond the maximum amplitude at the time of ringing, the above-described deformation preventing structure is configured by the diaphragm stopper provided so as to abut on the inner peripheral side portion. If so, deformation of the diaphragm can be prevented by a simple configuration. Alternatively, in the above configuration, the deformation preventing structure can be configured by setting the cross-sectional shape in the radial direction of the inner peripheral side portion of the diaphragm to be uneven. In this deformation preventing structure, the rigidity of the inner peripheral side portion of the diaphragm can be enhanced, so that excessive deformation of the inner peripheral side portion can be prevented. Even when such a deformation preventing structure is employed, deformation of the diaphragm can be prevented by a simple configuration. Although it is the inner peripheral side that is particularly easily deformed in the diaphragm, if the radial cross-sectional shape of the outer peripheral side located on the outer peripheral side of the voice coil is set to be uneven, deformation of the diaphragm is prevented Can be achieved more reliably. Instead of this, it is possible to configure the above-mentioned deformation preventing structure by forming the inner peripheral side portion of the diaphragm in a substantially concave spherical shape. In this deformation preventing structure, by forming the inner peripheral side portion of the diaphragm in a substantially concave spherical shape from the beginning, it is possible to prevent the inner peripheral side portion from being deformed excessively. Even when such a deformation preventing structure is employed, deformation of the diaphragm can be prevented by a simple configuration. Further, in the above configuration, the above-mentioned deformation preventing structure is configured by forming a sound emission hole for radiating the sound from the diaphragm forward in an annular portion located in front of the voice coil in the cover. It is also possible. 12-05-2019 3 In this deformation preventing structure, it is possible to prevent excessive deformation of the inner peripheral side portion and the outer peripheral side portion by applying a wind pressure to a relatively high rigidity portion of the diaphragm. When such a deformation preventing structure is adopted, the deformation of the diaphragm can be prevented by a simple configuration only by devising the formation position of the sound output hole. Alternatively, in the above configuration, the deformation preventing structure can be configured by forming the sound output hole in the peripheral wall portion of the cover. In this deformation preventing structure, it is possible to prevent excessive deformation of the inner peripheral side portion and the outer peripheral side portion by preventing a large wind pressure from acting directly on the diaphragm in the direction perpendicular to the surface. . Even when such a deformation preventing structure is adopted, the deformation of the diaphragm can be prevented by a simple configuration in which only the formation position of the sound output hole is devised. Further, in the above configuration, when the diaphragm is deformed by a predetermined amount or more beyond the maximum amplitude at the time of ringing, the deformation is prevented by the voice coil stopper provided so as to abut the rear end of the voice coil from the rear side. By configuring the structure or a part of the structure, it is possible to prevent in advance the excessive deformation of the entire diaphragm and the application of an excessive force on the diaphragm. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an electroacoustic transducer 10 according to an embodiment of the present invention in a state of being disposed upward, and FIG. 2 is a plan view thereof. As shown in these figures, the electro-acoustic transducer 10 according to this embodiment is an electrodynamic electroacoustic transducer having an outer diameter of about 5 to 20 mm, and is a foldable type. It is used as a receiver or a speaker in a state mounted on a portable communication device such as a portable telephone. The electro-acoustic transducer 10 includes a diaphragm 12, a frame 14 supporting an outer peripheral edge 12 a of the diaphragm 12, a voice coil 16 whose front end is fixed to an annular flat portion 12 b of the diaphragm 12, and A magnetic circuit unit 18 in which a cylindrical magnetic gap for accommodating the rear end portion of the voice coil 16 is formed, and a cover 20 which covers the diaphragm 12 from the front side. The thickness of the diaphragm 12 is set to a value of 15 μm or less (for example, about 10 μm). In the diaphragm 12, the inner peripheral side portion 12A located on the inner peripheral side of the annular flat portion 12b is formed in a convex spherical shape, and the outer peripheral side portion 12B located on the outer peripheral side of the annular flat portion 12b is in the radial direction The cross-sectional shape is set to a convex arc shape. The diaphragm 12 vibrates within the range of the maximum amplitude shown by a two-dot chain line in FIG. 1 when the electroacoustic transducer 10 rings. The frame 14 is formed in a ring shape, and an annular flange portion 14 a is formed at the outer peripheral end thereof. A diaphragm support portion 14b for supporting the diaphragm 12 is formed on the inner peripheral side of the annular flange portion 14a in the frame 14. A plurality of diaphragm support portions 14b are 12-05-2019 4 provided on the inner peripheral side of the diaphragm support portion 14b in the circumferential direction. The sound release hole 14c is formed. A pair of terminal plates 28 to which the coil terminals of the voice coil 16 are conductively fixed is embedded and fixed to the frame 14. The magnetic circuit unit 18 is made of a steel base 22 formed in a substantially tray shape, a magnet 24 formed in a relatively thick disc shape, and a steel made in a relatively thin disc shape. It comprises a yoke 26 and is fixed to the inner peripheral end of the frame 14 at the outer peripheral part of the base 22. The cover 20 is a steel plate formed in a substantially reverse tray shape and made of steel, and is fixed to the diaphragm support portion 14 b of the frame 14 at the outer peripheral edge thereof. A circular sound emission hole 20a for radiating the sound from the diaphragm 12 forward is formed in the center of the cover 20. In the present embodiment, a diaphragm stopper 30 made of a synthetic resin and formed in a disc shape having a small diameter is provided on the upper surface of the central portion of the yoke 26 in the magnetic circuit unit 18. The diaphragm stopper 30 abuts against the inner peripheral side portion 12A when the diaphragm 12 is deformed by a predetermined amount or more beyond the maximum amplitude at the time of ringing, as a deformation preventing structure for preventing the diaphragm 12 from being deformed excessively. It is supposed to work. In the present embodiment, a synthetic resin voice coil stopper 32 formed in a ring shape is provided at the lower end of the inner peripheral wall of the peripheral wall of the base 22 of the magnetic circuit unit 18 as another deformation preventing structure. . The voice coil stopper 32 is in contact with the rear end of the voice coil 16 from the rear side when the diaphragm 12 is deformed by a predetermined amount or more beyond the maximum amplitude at the time of ringing. Next, the function and effect of the present embodiment will be described. Although the electroacoustic transducer 10 according to the present embodiment is mounted on a foldable portable communication device as described above, it is used as a receiver or a speaker. When the portable communication device is folded after use, a large wind pressure acts on the electroacoustic transducer 10 through the sound output hole 20 a of the cover 20 on the diaphragm 12. At this time, since the diaphragm 12 is formed of a thin film, the convex spherical inner peripheral portion 12A tends to be deformed into a concave spherical shape by wind pressure. However, in the present embodiment, the diaphragm stopper 30 provided at the central portion of the yoke 26 abuts on the central portion of the inner peripheral side portion 12A to be deformed to prevent further deformation. Accordingly, it is possible to prevent the inner peripheral side portion 12A from being deformed into a concave spherical shape in advance. As described above, according to the present embodiment, since the diaphragm stopper 30 is provided as a deformation preventing structure, although the diaphragm 12 is formed of a thin film, the diaphragm 12 is excessively deformed by the wind pressure. Can be prevented in advance. And thereby, it is possible to eliminate the possibility that the acoustic characteristics set at the time of manufacture may be disturbed. Furthermore, in the present embodiment, the voice coil stopper 32 provided at the lower end portion of the inner peripheral wall of the base 12-05-2019 5 22 abuts on the rear end portion of the voice coil 16 from the rear side, and the diaphragm 12 is largely deformed rearward. As a result, it is possible to prevent in advance the diaphragm 12 from being deformed unexpectedly or the force exerted on the diaphragm 12 being exerted. In the present embodiment, the diaphragm stopper 30 is formed in a disk shape and provided on the upper surface of the central portion of the yoke 26. However, the diaphragm 12 has a predetermined amplitude or more exceeding the maximum amplitude at the time of ringing. Of course, any other shape or arrangement may be adopted as long as it is configured to be able to contact the inner peripheral side portion 12A when deformed. Further, in the present embodiment, the material of the diaphragm stopper 30 and the voice coil stopper 32 has been described as a synthetic resin, but the specific material is not particularly limited. A soft resin such as a thermoelastomer can be employed. Alternatively, it is also possible to adopt a hard resin, and it is also possible to adopt a material other than a synthetic resin such as, for example, rubber or metal. FIG. 3 is a view similar to FIG. 1 showing a first modification of the embodiment. As shown in this figure, in the present modification, the diaphragm stopper 30 as in the above embodiment is not provided, and instead, the radial cross-sectional shape of the inner peripheral portion 12A of the diaphragm 12 is uneven It is set in a shape, and this constitutes a deformation preventing structure. Further, in the present modification, the radial cross-sectional shape of the outer peripheral side portion 12B of the diaphragm 12 is also set to be uneven. Also in this modification, the basic configuration of the electroacoustic transducer 10 is the same as that of the above-described embodiment, and the voice coil stopper 32 is also the same as that of the above-described embodiment. In the deformation preventing structure of the present modification, by increasing the rigidity of the inner peripheral side portion 12A of the diaphragm 12, it is possible to prevent the inner peripheral side portion 12A from being deformed excessively. Even when such a deformation preventing structure is adopted, the deformation of the diaphragm 12 can be prevented by a simple configuration. Further, in the present modification, the rigidity of the outer peripheral side portion 12B of the diaphragm 12 can be enhanced, so that deformation of the diaphragm 12 can be prevented more reliably. FIG. 4 is a view similar to FIG. 1 showing a second modification of the embodiment. As shown in this figure, in the present modification, the sound output hole 20a is not formed at the central portion of the cover 20 as in the above embodiment, but is formed at the annular portion of the cover 20 located in front of the voice coil 16. Thus, the deformation preventing structure is configured. At this time, a plurality of sound release holes 20a are formed at predetermined intervals in the circumferential direction. Also in this modification, the basic configuration of the electroacoustic transducer 10 is the same as that of the above-described embodiment, and the voice coil stopper 32 is also the same as that of the above-described embodiment. In the deformation preventing structure of the present modification, the sound output hole 20 a is formed in the annular portion of the cover 20 located in front of the voice coil 16, so that the annular flat portion having a relatively high rigidity in the diaphragm 12. Since wind pressure can be applied to 12b, excessive deformation of the inner peripheral side 12-05-2019 6 portion 12A and the outer peripheral side portion 12B can be prevented. As described above, in the present modification, the deformation of the diaphragm 12 can be prevented by a simple configuration in which only the formation position of the sound output hole 20a is devised. FIG. 5 is a view similar to FIG. 1 showing a third modification of the embodiment. As shown in this figure, in the present modification, the sound output hole 20a is formed not in the central portion of the cover 20 but in the peripheral wall portion, thereby constituting a deformation preventing structure. At this time, a plurality of sound release holes 20a are formed at predetermined intervals in the circumferential direction. Also in this modification, the basic configuration of the electroacoustic transducer 10 is the same as that of the above-described embodiment, and the voice coil stopper 32 is also the same as that of the above-described embodiment. In the deformation preventing structure of the present modification, by forming the sound output hole 20 a in the peripheral wall portion of the cover 20, the direct wind direction does not act directly on the diaphragm 12. As a result, excessive deformation of the inner circumferential portion 12A and the outer circumferential portion 12B can be prevented. As described above, also in the present modification, it is possible to prevent the deformation of the diaphragm 12 by a simple configuration in which only the formation position of the sound output hole 20a is devised. FIG. 6 is a view similar to FIG. 1 showing a fourth modification of the embodiment. As shown in this figure, in the present modification, the inner peripheral side portion 12 A of the diaphragm 12 is formed in a concave spherical shape, thereby constituting a deformation preventing structure. In the above embodiment, the magnetic circuit unit 18 is configured as an internal magnet type unit in which the magnet 24 is disposed on the inner peripheral side of the voice coil 16, but in the present modification, the voice coil 16 is The magnet 24 is arranged on the outer peripheral side of the unit as an external magnet type unit. The configuration other than this is the same as that of the above embodiment, including the point that the voice coil stopper 32 is provided. In the deformation preventing structure of the present modification, since the inner peripheral side portion 12A of the diaphragm 12 is initially formed in a concave spherical shape, a large wind pressure acts on the diaphragm 12 through the sound release hole 20a. Also, unlike the substantially convex spherical shape, since it is difficult to physically deform further in the concave direction, it is possible to prevent the inner peripheral side portion 12A from being deformed excessively. Even when such a deformation preventing structure is adopted, the deformation of the diaphragm 12 can be prevented by a simple configuration. In this modification, since the magnetic circuit unit 18 is configured as an external magnet type unit, even if the inner peripheral side portion 12 A of the diaphragm 12 is formed into a concave spherical shape, the inner peripheral side at the time of ringing Interference of the portion 12A with the magnetic circuit unit 18 can be easily avoided. Although the voice coil stopper 32 is provided as another deformation preventing structure in addition to the respective deformation 12-05-2019 7 preventing structures in the above embodiment and each modification, the voice coil stopper is described. Even in the configuration in which 32 is not provided, excessive deformation of the inner peripheral side portion 12A which is particularly easily deformed in the diaphragm 12 can be prevented in advance. Alternatively, in the above-described embodiment and each modification, even when the voice coil stopper 32 is provided even in the configuration in which the respective deformation preventing structures are not provided, the entire diaphragm 12 is largely deformed and thus the voice coil stopper 32 is provided. Unreasonable force acting on the diaphragm 12 can be prevented in advance. Further, the deformation preventing structures of the above-described embodiment and the respective modified examples may be appropriately combined and used. In this case, deformation of the diaphragm 12 can be prevented more effectively. Furthermore, in the electro-acoustic transducer 10 according to the above-described embodiment and each modification, the outer shape of the diaphragm 12 is described as being circular, but, for example, the outer shape other than circular such as oval or square Also in the electro-acoustic transducer provided with the diaphragm, it is possible to obtain the same operation and effect as those described above by adopting the same configuration as that of the above-described embodiment and the respective modifications. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross-sectional view showing an electro-acoustic transducer according to an embodiment of the present invention disposed upward, and FIG. 2 is a diagram showing the electro-acoustic transducer disposed upward FIG. 3 is a plan view showing a first modification of the embodiment, similar to FIG. 1, and FIG. 4 is a view similar to FIG. 1 showing a second modification of the embodiment. A diagram similar to FIG. 1 showing a third modification of the embodiment [FIG. 6] A diagram similar to FIG. 1 showing a fourth modification of the embodiment [Description of the reference numerals] 10 electroacoustic transducer 12 diaphragm 12A Inner part 12B Outer part 12a Outer peripheral part 12b Annular flat part 14 Frame 14a Annular flange part 14b Diaphragm support part 14c Sound output hole 16 Voice coil 18 Magnetic circuit unit 20 Cover 20a Sound output hole 22 Base 24 magnet 26 yoke 28 terminal plate 30 diaphragm stopper 32 voice coil stopper 12-05-2019 8
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