JP3149412B2 - Electromagnetic electroacoustic transducer and portable terminal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroacoustic transducer mounted on a portable terminal such as a portable telephone or a pager and used for reproducing an alarm sound when a call is received.

[0002]

2. Description of the Related Art FIG. 9A is a plan view of a conventional electromagnetic electro-acoustic transducer, and FIG. 9B is a cross-sectional view thereof. The conventional electromagnetic electroacoustic transducer has a cylindrical housing 107 and a disk-shaped yoke 106 arranged to cover the bottom surface of the housing 107. A center pole 103 formed integrally with the yoke is provided. A coil 10 is provided around the center pole 103.
Four are wound. An annular magnet 105 is provided on the outer periphery of the coil 104, and an appropriate interval is provided over the entire periphery between the coil 104 and the inner peripheral surface of the magnet 105. The outer peripheral surface of the magnet 105 is in contact with the inner peripheral surface of the housing 107. A disk-shaped non-magnetic first diaphragm 100 is supported at the upper end of the casing 107. The first diaphragm 100 is disposed between the first diaphragm 100, the magnet 105, the coil 104, and the center pole 103. Are provided at appropriate intervals. At the center of the first diaphragm 100, a second diaphragm 101, which is a disk-shaped magnetic body, is provided concentrically with the first diaphragm 100.

The operation and effect of the electromagnetic electro-acoustic transducer configured as described above will be described. Coil 10
In the initial state where no current flows through the magnet 4, the magnet 105,
Second diaphragm 101, center pole 103, yoke 1
06, a magnetic path is formed, and the second diaphragm 10
1 is attracted to the magnet 105 and the center pole 103 side, and is displaced until it becomes equal to the elastic force of the first diaphragm 100. When an AC current flows through the coil 104 in such an initial state, an AC magnetic field is generated in the magnetic path, and an AC driving force is generated on the second diaphragm 101. When such an AC driving force is generated in the second diaphragm 101, the second diaphragm 101 interacts with the fixed first diaphragm 100 due to the interaction with the static attraction generated by the magnet 105. Vibrates from the initial state. The vibration is emitted as sound. However, in the above configuration, the distance between the magnet 105 and the second diaphragm 101 is large,
The magnetic flux cannot effectively act on the second diaphragm 101.

FIG. 10 is a magnetic flux vector diagram of the conventional electromagnetic electroacoustic transducer shown in FIG. In this magnetic flux vector diagram, only one half of the center axis is displayed, and the first diaphragm 100 and the housing 107 are not displayed because they are nonmagnetic materials. In the conventional electromagnetic electroacoustic transducer, a magnetic path is formed in the second diaphragm 101 from the magnet 105 via a large magnetic gap. Therefore,
Since a layer of air acting as a magnetic resistance is large, it is difficult to supply a sufficient magnetic flux to the second diaphragm 101 from a magnetic path from the center of the magnet 105.

There is also a means of using a magnetic material as the material of the first diaphragm 100 and using it as a magnetic path. However, also in this case, if the resonance frequency is designed to match the frequency reproduced as the alarm sound, it is difficult to give the first diaphragm a thickness that can be used without magnetic saturation as a magnetic path.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and a magnetic thin plate is disposed between a magnet and a first diaphragm so that a magnet and a second diaphragm are disposed.
By reinforcing the magnetic path between the diaphragms and efficiently generating a static attraction force and an AC driving force on the second diaphragm,
It is an object of the present invention to provide a highly efficient electromagnetic electro-acoustic transducer without changing the size of the magnet and the second diaphragm.

[0007]

SUMMARY OF THE INVENTION The electromagnetic electroacoustic of the present invention
The transducer is provided at the first diaphragm and at the center of the first diaphragm.
A second vibrating plate made of magnetic material and a first vibrating plate
And a first diaphragm of the yoke
A center pole provided on the surface facing the
A coil placed around the pole and the coil
Magnet and the first vibration
The inner peripheral edge is provided between the moving plate and the outer peripheral surface of the second diaphragm.
The outer peripheral edge overlaps the edge and the magnetic field generated on the magnet surface
The direction of the bundle vector is radially centered and outer
A magnetic thin plate that almost coincides with the switching neutral point.
Thus, the above object is achieved.

[0008] The electromagnetic electro-acoustic transducer of the present invention comprises :
A vibrating plate and a magnetic body provided at the center of the first vibrating plate
And a second diaphragm which is provided to face the first diaphragm.
The yoke and the surface of the yoke facing the first diaphragm.
Around the center pole and the center pole
And the coil arranged around the coil,
A concave portion on the inner peripheral side of the surface facing the first diaphragm
Provided between the magnet and the magnet and the first diaphragm
The inner peripheral edge overlaps the outer peripheral edge of the second diaphragm,
A magnetic thin plate fitted in the recess of the gnet.
Thus, the above object is achieved.

The first diaphragm, the magnet and the yoke
At least one is composed of the first diaphragm, magnet and yoke.
At least one that connects the space to be formed and the external space
An air hole may be provided.

[0010] The electromagnetic electro-acoustic transducer of the present invention comprises :
A housing for supporting the diaphragm may be further provided.

At least the first diaphragm, the housing and the yoke
One is an empty space composed of a first diaphragm, a housing and a yoke.
At least one air hole is provided for communication between the space and the external space.
You may be.

A magnetic thin plate overlapping the outer diameter of the second diaphragm
Is 4% to 15% of the outer diameter of the second diaphragm
There may be.

The inner diameter of the magnetic thin plate is less than the inner diameter of the magnet
It may be.

The second diaphragm has a plurality of radially projecting plates.
May be provided in the circumferential direction.

The specific gravity of the material constituting the first diaphragm is
The specific gravity of the material constituting the second diaphragm may be lower than the specific gravity.

The portable terminal device according to the present invention has the above-described power supply.
A magnetic electroacoustic transducer may be incorporated.

The electromagnetic electro-acoustic transducer according to the present invention has a first
A vibrating plate and a magnetic body provided at the center of the first vibrating plate
And a second diaphragm which is provided to face the first diaphragm.
The yoke and the surface of the yoke facing the first diaphragm.
Around the center pole and the center pole
And the coil placed around the coil
Provided between the magnet and the magnet and the first diaphragm
The inner peripheral edge overlaps the outer peripheral edge of the second diaphragm,
The radial length overlapping the outer diameter of the second diaphragm is the second vibration
A magnetic thin plate that is 4% to 15% of the outer diameter of the plate,
Thereby, the above object is achieved.

[0018]

[0019]

[0020]

[0021]

[0022]

According to the present invention, a portable terminal device capable of reproducing a high sound pressure alarm sound without changing the capacity of a portable telephone having a built-in electromagnetic electroacoustic transducer can be realized.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 show an electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention.
This will be described with reference to FIG. FIG. 1 is a sectional view of an electromagnetic electroacoustic transducer according to Embodiment 1 of the present invention. The electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention includes a cylindrical housing 7 and a disk-shaped yoke 6 arranged to cover the bottom surface of the housing 7. A center pole 3 integrally formed with the yoke is provided at the center of the yoke 6. A coil 4 is wound around the center pole 3. An annular magnet 5 is provided on the outer periphery of the coil 4, and an appropriate interval is provided between the coil 4 and the inner peripheral surface of the magnet 5 over the entire circumference. The outer peripheral surface of the magnet 5 is in contact with the inner peripheral surface of the housing 7. An annular magnetic thin plate 9 is provided on the upper surface of the magnet 5 so as to cover the entire upper surface of the magnet 5.
The tip of the center pole 3 is located inside the inner periphery of the center pole. The inner diameter of the magnetic thin plate 9 is smaller than the inner diameter of the magnet 5, and the inner peripheral edge of the magnetic thin plate 9 extends inward from the inner peripheral surface of the magnet 5. A nonmagnetic disk-shaped first diaphragm 1 is supported at the upper end of the housing 7 so as to be able to vibrate. The first diaphragm 1, the magnetic thin plate 9, the coil 4, and the center pole 3 is provided with an appropriate interval. At the center of the first diaphragm 1, a disk-shaped second diaphragm 2 made of a magnetic material, for example, a permalloy, is provided concentrically with the first diaphragm 1. The inner diameter of the magnetic thin plate 9 is smaller than the outer diameter of the second diaphragm 2, so that the inner peripheral edge of the magnetic thin plate 9 overlaps the outer peripheral edge of the second diaphragm 2. The yoke 6 has a space between the coil 4 and the inner peripheral surface of the magnet 5, the first diaphragm 1 and the yoke 6.
A plurality of air holes 8 communicating with the outside of the space between them are provided at appropriate intervals in the circumferential direction. Each air hole 8
Is configured to release air between the coil 4 and the inner peripheral surface of the magnet 5 to the outside to reduce an acoustic load applied to the first diaphragm 1.

The operation and effects of the electromagnetic electroacoustic transducer configured as described above will be described. In an initial state in which no current flows through the coil 4, a magnetic path is formed by the magnet 5, the magnetic thin plate 9, the second diaphragm 2, the center pole 3, and the yoke 6. And is attracted to the center pole 3 side, and is displaced until it becomes equal to the elastic force of the first diaphragm 1. When an AC current flows through the coil 4 in such an initial state, an AC magnetic field is generated in the magnetic path, and an AC driving force is generated on the second diaphragm 2. When such an AC driving force is generated in the second diaphragm 2, the second diaphragm 2 interacts with the fixed first diaphragm 1 due to the interaction with the static attraction generated by the magnet 5. Vibrates from the initial state. The vibration is emitted as sound.

In the first embodiment of the present invention, since the magnetic thin plate 9 is provided between the magnet 5 and the second diaphragm 2, the magnetic resistance is suppressed, and the magnetic flux in the magnetic path is reduced. Density is increasing. As a result, the second diaphragm 2
The AC driving force applied to the first diaphragm 1 and the second diaphragm 2 vibrate with a larger amplitude, so that the reproduced sound pressure increases. When the magnetic thin plate 9 is provided, the case where the magnetic thin plate 9 is not provided is
The static suction force increases by about 71%, and the AC driving force increases by about 43%.

FIG. 2 is a graph showing the relationship between the AC driving force and the overlap ratio between the inner peripheral edge of the magnetic thin plate 9 and the outer peripheral edge of the second diaphragm 2. Here, the duplication ratio means the magnetic thin plate 9
Of the second diaphragm 2 and the length of the outer diameter of the second diaphragm 2. FIG.
In the graph, the horizontal axis represents the overlap ratio, and the vertical axis represents the AC driving force. When the overlapping ratio becomes about 9%, the AC driving force becomes maximum. When the overlapping ratio is 5%, the static suction force is used for the case where the inner diameter of the magnetic thin plate 9 and the outer diameter of the second diaphragm 2 coincide with each other and the overlapping ratio is 0%. It is increased by 21% and 10% by the AC driving force. According to the graph of FIG. 2, in order to further increase the AC driving force, it is preferable to set the overlap ratio to about 4% to 15%.

In the electromagnetic electro-acoustic transducer according to the first embodiment of the present invention shown in FIG. 1, the inner diameter of the magnetic thin plate 9 is smaller than the inner diameter of the magnet 5; Is smaller than the outer diameter of the second diaphragm 2, the inner diameter of the magnetic thin plate 9 may be the same as or larger than the inner diameter of the magnet 5. The magnetic thin plate 9
Is not required to be in contact with the magnet 5 if it is arranged between the magnet 5 and the first diaphragm 1.
Further, in order to suppress the magnetic resistance and increase the magnetic flux density in the magnetic path, the magnetic thin plate 9 preferably has a thickness that does not cause magnetic saturation.

(Embodiment 2) FIG. 3 is a sectional view of an electromagnetic electroacoustic transducer according to Embodiment 2 of the present invention.
In the electromagnetic electro-acoustic transducer shown in FIG. 3, a concave portion into which the magnetic thin plate 19 is fitted is provided in an inner peripheral portion of the upper surface of the magnet 15, and the magnetic thin plate 19 is fitted into the concave portion, 15 and is fixed integrally. The inner peripheral edge of the magnetic thin plate 19 protrudes from the inner peripheral edge of the magnet 15. Other configurations are the same as those of the electromagnetic electro-acoustic transducer according to the first embodiment of the present invention shown in FIG.

In the electromagnetic electro-acoustic transducer configured as described above, by inserting the magnetic thin plate 19 into the magnet 15, the static attractive force generated by the magnet 15 and the AC drive applied to the second diaphragm 2 are obtained. The overall height of the electromagnetic electro-acoustic transducer can be reduced with little reduction in force.

FIG. 4 is a magnetic flux vector diagram of the electromagnetic electroacoustic transducer shown in FIG. In this magnetic flux vector diagram, only the magnetic flux vector of one half with respect to the central axis is displayed,
The diaphragm 1 and the housing 7 are not shown in FIG. 4 because they are non-magnetic materials. Also, the holes 8 are not shown in FIG. 4 in order to more appropriately display the magnetic path. As shown in FIG. 4, the direction of the magnetic flux vector generated on the magnet 15 is switched between the center direction and the outer peripheral direction at a neutral point in the radial direction of the magnet 15. In this case, since the magnet 15 is provided with the magnetic thin plate 19, the magnetic flux from the center of the magnet 15 toward the center can also be concentrated near the inner peripheral edge of the magnet 15 by the magnetic thin plate 19. In addition, since the air layer in the magnetic path between the central portion of the magnet 15 and the second diaphragm 2 is small and the magnetic resistance is reduced, the magnetic flux is efficiently supplied to the second diaphragm 2. Becomes possible.

Since the direction of the magnetic flux vector generated on the magnet 15 is switched between the center direction and the outer circumferential direction at a radial neutral point, the maximum magnetic flux vector generated toward the center along the outer diameter of the magnetic thin plate 19 is generated. By adjusting to the diameter, that is, by making the outer peripheral edge of the magnetic thin plate 19 substantially coincide with the neutral point,
Can concentrate the magnetic flux heading toward the center of the magnet 15 on the second diaphragm 2 most effectively.

FIG. 5 is a graph showing the relationship between the outer diameter of the magnetic thin plate 19 and the static attraction force and the AC driving force applied to the second diaphragm 2. In this graph, the horizontal axis represents the outer diameter of the magnetic thin plate 19, and the vertical axis represents the static attraction force and the AC driving force applied to the second diaphragm 2, which are static near the neutral point shown in FIG. It can be seen that the suction force is at a maximum.

(Embodiment 3) FIG. 6 is a sectional view of an electromagnetic electroacoustic transducer according to Embodiment 3 of the present invention.
In the electromagnetic electro-acoustic transducer shown in FIG. 6, the magnet 15 is arranged so that a space is formed between the outer peripheral surface of the magnet 15 and the inner peripheral surface of the housing 7, and the space and the first A plurality of air holes 28 communicating with the outside of the space between the diaphragm 1 and the yoke 26 are provided in the yoke 26 at appropriate intervals in the circumferential direction. Other configurations are the same as those of the electromagnetic electro-acoustic transducer according to the second embodiment of the present invention shown in FIG.

In the electromagnetic electroacoustic transducer configured as described above, the air between the outer peripheral surface of the magnet 15 and the inner peripheral surface of the housing 7 is discharged to the outside through each air hole 28. You. By providing the air hole 28 on the outer peripheral side portion of the yoke 26, the magnet 15 can be provided on the center side of the yoke 26. In addition, since the air holes 28 are outside the magnet 15 and the magnetic thin plate 19 does not block the air passage between the first diaphragm 1 and the air holes 28, the inner peripheral edge of the magnetic thin plate 19 The inner diameter of the magnetic thin plate 19 can be made smaller so that Thereby, the outer peripheral edge is overlapped with the inner peripheral edge of the magnetic thin plate 19 in the second position.
The outer diameter of the diaphragm 2 can also be reduced. As the outer diameter of the second diaphragm 2 becomes smaller, the elastic supporting portion of the first diaphragm 1 other than the portion supporting the second diaphragm 2 becomes wider, and when the second diaphragm 2 vibrates. Can be increased, so that the reproduced sound pressure can be increased.

(Embodiment 4) FIG. 7A is a plan view of an electromagnetic electroacoustic transducer according to Embodiment 4 of the present invention.
FIG. 7B is a cross-sectional view taken along line II of FIG. 7A. In the electromagnetic electro-acoustic transducer shown in FIG. 7, the second diaphragm 32 fixed to the center of the first diaphragm 1 has a plurality of circular peripheral portions that are notched to form a circular plate. A plurality of protruding portions projecting in the direction are provided at equal intervals in the circumferential direction. Each protrusion has a side edge along a quadratic curve so that the sum of the cross-sectional areas is constant at any position in the radial direction. The thickness of the second diaphragm 32 is preferably larger than that of the first diaphragm 1. Other configurations are the same as those of the electromagnetic electro-acoustic transducer according to the third embodiment of the present invention shown in FIG.

In the second diaphragm 2 according to the first to third embodiments of the present invention, the shape of the second diaphragm 2 is disc-shaped, so that the cross-sectional area over the entire circumference in a predetermined position in the radial direction is larger on the outer peripheral side. The cross-sectional area over the entire circumference in the circumferential direction is non-uniform in the radial direction. Since the magnetic flux density in the magnetic body is inversely proportional to the cross-sectional area through which the magnetic flux passes, the magnetic flux density inside the second diaphragm 2 becomes non-uniform in the radial direction. But,
The second diaphragm 32 in the fourth embodiment of the present invention has a total sum of the cross-sectional areas of the respective projections at any position in the radial direction in the outer peripheral portion where the projections of the second diaphragm 32 are provided. Each protrusion is formed so as to be constant. Therefore, the magnetic flux density is made uniform at the outer peripheral portion of the second diaphragm 32 where the protrusion is provided.

By cutting the peripheral portion of the second diaphragm 32 to such an extent that magnetic saturation does not occur, the amount of magnetic flux passing through the second diaphragm 32 can reduce the amount of magnetic flux passing through the disk-shaped second diaphragm 2. The AC driving force acting on the second diaphragm 32 can be substantially the same as that of the second diaphragm 2 without much difference from the amount of magnetic flux passing therethrough. As a result, the vibration of the second diaphragm 32 having a uniform magnetic flux density produces sound without deteriorating characteristics.

In the electromagnetic electro-acoustic transducer shown in FIG. 7, the second diaphragm 32, which is thicker than the first diaphragm 1, is formed by cutting out the peripheral portion. And the entire mass of the second diaphragm 32 is the second diaphragm 2
As described above, the weight is reduced as compared with the case where the notch is not provided, and as a result, the reproduced sound pressure level can be increased. It is preferable that the protruding portion of the second diaphragm 32 be provided on the outer peripheral side of a portion of the second diaphragm 32 facing the center pole 3.

In the electromagnetic electroacoustic transducer shown in FIG. 7, the second diaphragm 32 is formed by cutting a circular plate to reduce the weight of the whole diaphragm. The same effect can be obtained even if the weight is reduced by using a material having a small specific gravity as the material. For example, the same effect can be obtained by changing permalloy, which is also used as the first diaphragm material, to titanium having a low specific gravity.

In the electromagnetic electroacoustic transducers according to the second to fourth embodiments of the present invention shown in FIGS. 3, 6, and 7, the inner diameter of the magnetic thin plate 19 is smaller than the inner diameter of the magnet 15. However, if the inner diameter of the magnetic thin plate 19 is smaller than the outer diameter of the second diaphragm 2 or the second diaphragm 32, the inner diameter of the magnetic thin plate 19 is equal to or larger than the inner diameter of the magnet 15. Is also good. Further, in order to suppress the magnetic resistance and increase the magnetic flux density in the magnetic path, the magnetic thin plate 19 preferably has a thickness that does not cause magnetic saturation.

FIG. 8 is a partially broken perspective view of a portable telephone as an example of a portable terminal provided with the electromagnetic electro-acoustic transducer of the present invention. The electromagnetic electro-acoustic transducer used in this mobile phone is the same as that shown in the first to fourth embodiments of the present invention.

The portable telephone 61 has a housing 62, and a sound hole 63 is provided on one side of the housing 62. Inside the housing 62, the electromagnetic electro-acoustic transducer 10 of the present invention is provided so that the first diaphragm 1 faces the sound hole 63. The mobile phone 61 has a built-in signal processing circuit (not shown) for converting a calling signal for receiving a signal and inputting the signal to the electromagnetic electro-acoustic transducer 10. When the signal processing circuit of the mobile phone 61 receives the signal indicating the incoming call, the signal is transmitted to the electromagnetic electroacoustic transducer 10.
And a ringtone is played. As a result, the user can know the incoming call.

In the portable telephone 61 in which the electromagnetic electro-acoustic transducer 10 of the present invention is used, without taking measures such as increasing the size of the second diaphragm and the magnet,
The reproduction sound pressure of the ringing tone can be increased. Therefore, the mobile phone 6 incorporating the electromagnetic electroacoustic transducer 10
It is possible to provide a high sound pressure ringing tone without increasing the capacity of 1 itself.

In the mobile phone 61, the electromagnetic electroacoustic transducer 10 is directly mounted on the housing 62, but may be mounted on a substrate built in the mobile phone 61. Also, an acoustic port may be added to further increase the sound pressure of the ringing tone.

FIG. 8 shows a portable telephone as an example of the portable terminal, but the present invention is not limited to this.

In the embodiment of the present invention, the case where the shape of the magnetic thin plate is annular is disclosed, but the shape of the magnetic thin plate is not limited to the annular shape, and the annular magnetic thin plate has a notch. Alternatively, the magnetic body thin plate may be configured by intermittently arranging a plurality of magnetic bodies in the circumferential direction of the upper surface of the magnet.

Further, in the embodiment of the present invention, the components for vibrating and supporting the first diaphragm are not limited to the housing. Any component may be used as long as the first diaphragm can be supported or fixed so as to be able to vibrate.

Further, in the embodiment of the present invention, a closed space is formed by the first diaphragm, the housing, and the yoke, but the closed space is formed by the first diaphragm, the magnet, the yoke, And in this case,
The first diaphragm is supported by a magnet. Also,
The closed space may be formed by the first diaphragm and the housing. In addition, the air hole that communicates the closed space with the outside of the closed space may be provided in any component constituting the electromagnetic electro-acoustic transducer of the present invention.

[0051]

According to the electromagnetic electro-acoustic transducer of the present invention, since the magnetic thin plate whose inner diameter is smaller than the outer diameter of the second diaphragm is arranged on the upper surface of the magnet, the magnet and the second vibrator can be used. The magnetic resistance can be reduced without increasing the size of the plate, so that the static attraction force and the AC driving force can be increased. As a result, the size of the second diaphragm can be reduced, so that the mass of the entire diaphragm can be reduced and the reproduced sound pressure can be increased. Furthermore, a concave portion is provided on the inner peripheral side of the magnet upper surface, and a magnetic thin plate is fitted therein, so that the overall height of the electromagnetic electro-acoustic transducer can be reduced. Further, by providing a cut-out portion in the second diaphragm or using a material having a small specific gravity as the material of the first diaphragm, it is possible to reduce the weight of the entire diaphragm and to improve the reproduction sound pressure level. Can be. First
An air hole for bleeding air between the vibrating plate and the yoke is disposed on the outer peripheral side of the yoke to reduce the inner diameter of the magnetic thin plate and the outer diameter of the second vibrating plate, thereby achieving the first diaphragm. The width of the elastic supporting portion of the diaphragm can be increased to increase the amplitude.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electromagnetic electroacoustic transducer according to Embodiment 1 of the present invention.

FIG. 2 is a graph showing a relationship between an overlapping ratio of an inner diameter of a magnetic thin plate and an outer diameter of a second diaphragm and an AC driving force according to the first embodiment of the present invention.

FIG. 3 is a sectional view of an electromagnetic electro-acoustic transducer according to Embodiment 2 of the present invention.

FIG. 4 is a magnetic flux vector diagram of the electromagnetic electroacoustic transducer according to Embodiment 2 of the present invention.

FIG. 5 is a graph showing a relationship between an outer diameter of a magnetic thin plate and a static attraction force and an AC driving force according to the second embodiment of the present invention.

FIG. 6 is a sectional view of an electromagnetic electroacoustic transducer according to Embodiment 3 of the present invention.

FIG. 7A is a plan view of an electromagnetic electroacoustic transducer according to Embodiment 4 of the present invention. (B) is a sectional view of the electromagnetic electro-acoustic transducer according to Embodiment 4 of the present invention.

FIG. 8 is a partially cutaway perspective view of a portable terminal equipped with the electromagnetic electro-acoustic transducer of the present invention.

FIG. 9A is a plan view of a conventional electromagnetic electro-acoustic transducer. (B) is a sectional view of a conventional electromagnetic electroacoustic transducer.

FIG. 10 is a magnetic flux vector diagram of a conventional electromagnetic electroacoustic transducer.

[Explanation of symbols]

 1, 100 First diaphragm 2, 32, 101 Second diaphragm 3, 103 Center pole 4, 104 Coil 5, 15, 105 Magnet 6, 26, 106 Yoke 7 Housing 8, 28 Air hole 9, 19 Magnetic thin plate 10 Electromagnetic electroacoustic transducer 61 Mobile phone

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04R 13/02 G10K 9/13 101 H04M 1/02 H04M 1/03

Claims (11)

(57) [Claims] [1 claim: a first diaphragm, wherein provided in the center portion of the first diaphragm, a second diaphragm of a magnetic material, provided opposite to the first diaphragm a yoke, a center pole provided on the surface facing the first diaphragm of the yoke, and arranged coils so as to surround the center pole, a magnet arranged so as to surround the coil, the provided between the magnet first diaphragm,
The inner peripheral edge portion overlaps the outer peripheral edge of the second diaphragm, the
Magnetic flux vector whose outer peripheral edge is generated on the magnet surface
Is switched in the radial direction between the center direction and the outer peripheral direction
A magnetic thin plate substantially coincident with a neutral point . 2. A first vibrating plate and a magnetic material provided at a central portion of the first vibrating plate.
A second diaphragm, a yoke provided to face the first diaphragm , and a yoke provided on a surface of the yoke facing the first diaphragm.
And the center pole was a arranged coils so as to surround the center pole is disposed to surround said coil, and a magnet which have a recess on the inner peripheral portion of the first diaphragm and opposing surfaces, Provided between the magnet and the first diaphragm,
An inner peripheral edge overlaps an outer peripheral edge of the second diaphragm,
An electromagnetic electro-acoustic transducer , comprising: a magnetic thin plate fitted in a recess of a magnet . 3. The apparatus according to claim 1, wherein said first diaphragm, said magnet, and
At least one of the yokes has a space formed by the first diaphragm, the magnet, and the yoke , and an external space.
At least one air hole communicating provided a
The electromagnetic electro-acoustic transducer according to claim 1 . Wherein further comprising a housing for supporting the first diaphragm, the electromagnetic transducer according to claim 1 or 2. 5. at least one of the said first diaphragm and the housing yoke, wherein the first diaphragm and the housing
5. The electromagnetic electro-acoustic transducer according to claim 4 , wherein at least one air hole communicating the space defined by the yoke and the external space is provided. 6. 4% to 15% of the outer diameter of the second diaphragm the magnetic radial direction of the length a second diaphragm of the sheet that overlaps with the outer diameter of claim 1 or 3. The electromagnetic electroacoustic transducer according to 2 . Wherein said inner diameter of the thin magnetic plate is equal to or less than the inner diameter of the magnet, the electromagnetic transducer according to claim 1 or 2. The method according to claim 8, wherein said second diaphragm, a plurality of protruding portions protruding in a radial direction are provided in the circumferential direction, according to claim 1 or
Or an electromagnetic electroacoustic transducer according to 2 . The specific gravity of 9. The material constituting the first diaphragm is a specific gravity less of the material of the second diaphragm, the electromagnetic transducer according to claim 1 or 2. 10. A portable terminal device incorporating the electromagnetic transducer according to any of claims 1-9. 11. A first vibrating plate, and a magnetic material provided at a central portion of the first vibrating plate.
A second diaphragm, a yoke provided to face the first diaphragm , and a yoke provided on a surface of the yoke facing the first diaphragm.
Center pole, a coil arranged to surround the center pole, a magnet arranged to surround the coil, and provided between the magnet and the first diaphragm,
An inner peripheral edge overlaps an outer peripheral edge of the second diaphragm,
The radial length overlapping the outer diameter of the second diaphragm is the second diaphragm.
And a thin magnetic plate is 4% to 15% of the outer diameter of the diaphragm of the electromagnetic type electroacoustic transducer.