JP2002051396A - Electromagnetic electroacoustic transducer and portable terminal unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electromagnetic electroacoustic transducer than can reproduce high-range sound pressure as well as low-range sounds. SOLUTION: This electromagnetic electroacoustic transducer is provided with a first diaphragm, a second diaphragm which is provided at the center of the first diaphragm and composed of a magnetic body having a first hole in its central part, and a yoke which is set up to face the first diaphragm. The transducer is also provided with a center pole, which is provided on the first diaphragm side with respect to the yoke and has such a shape that can be inserted into the first hole, a coil arranged to surround the center pole, and a first magnet arranged so as to surround the coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a mobile phone,
Installed in portable terminals such as pagers (registered trademark),
The present invention relates to an electroacoustic transducer used for reproducing an alarm sound, a melody sound, a voice, and the like at the time of an incoming call.

[0002]

2. Description of the Related Art FIG. 12A is a plan view of a conventional electromagnetic electro-acoustic transducer, and FIG.

A conventional electromagnetic electro-acoustic transducer 200 has a cylindrical housing 107 and a disk-shaped yoke 106 arranged so as to cover the bottom surface of the housing 107. A center pole 103 formed integrally with the yoke is provided at the center of the center pole. Center pole 10
A coil 104 is wound around 3. Coil 10
An annular magnet 105 is provided on the outer periphery of 4, and an appropriate interval is provided over the entire periphery between the coil 104 and the inner peripheral surface of the magnet 105. Magnet 10
The outer peripheral surface of 5 is in contact with the inner peripheral surface of the housing 107. A first diaphragm 100 having a disc shape is supported on an upper end portion of the housing 107. The first diaphragm 100, the magnet 105, the coil 104, and the center pole 10 are supported.
3 is provided with an appropriate interval. 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 effects of the electromagnetic electroacoustic transducer 200 configured as described above will be described.

In an initial state in which no current flows through the coil 104, a magnetic path is formed by the magnet 105, the second diaphragm 101, the center pole 103, and the yoke 106. The first diaphragm 100 is sucked by the pole 103 and 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 in the second diaphragm 101. When such an AC driving force is generated in the second diaphragm 101, the second diaphragm 101
Due to the interaction between the static suction force generated by the vibration and the AC driving force, the actuator is displaced from the initial state together with the fixed first diaphragm 100. Vibration due to the displacement is radiated as sound.

[0006]

FIG. 13 shows a driving force characteristic generated on the second diaphragm 101 of the electromagnetic electro-acoustic transducer 200. As shown in FIG. The vertical axis represents the driving force, and the horizontal axis represents the second diaphragm 10.
1 shows the distance from the center pole 103 (that is, the magnetic gap value). FIG. 13 shows that when the magnetic gap value exceeds a certain value, the driving force decreases in proportion to the magnetic gap value. Therefore, if the amplitude necessary for realizing high sound pressure and low frequency reproduction is secured, the driving force is reduced, and it is difficult to realize high sound pressure. In FIG. 13, the reason why the driving force decreases in the vicinity of the center pole 103 is that the second diaphragm 101 is magnetically saturated.

In view of the above problems, the present invention enables high sound pressure and low frequency reproduction with a substantially smaller magnetic gap value and a larger driving force generated on the second diaphragm as compared with the prior art. It is an object of the present invention to provide a simple electromagnetic electro-acoustic transducer and a portable terminal device incorporating the same.

[0008]

According to the present invention, there is provided an electromagnetic electro-acoustic transducer according to the present invention, comprising a first diaphragm and a magnetic plate provided at the center of the first diaphragm and having a first hole formed at the center. The body is the second
A yoke provided opposite to the first diaphragm, a center pole provided on the first diaphragm side with respect to the yoke, and having a shape insertable into the first hole; A coil is provided so as to surround the pole, and a first magnet is provided so as to surround the coil, whereby the object is achieved.

According to the electromagnetic electroacoustic transducer described above, even if the magnetic gap in the height direction is increased, the AC driving force can be maintained at a high level only by changing the shape of the components without adding new parts. , Enabling high sound pressure and low frequency reproduction.

[0010] The first diaphragm may have a second hole into which the center pole can be inserted.

The height of the upper surface of the center pole may be higher than the lower surface of the second diaphragm.

According to the electromagnetic electroacoustic transducer, the distance between the center pole and the diaphragm can be kept substantially constant even at the time of amplitude, so that a stable AC driving force can be obtained.

[0013] A first magnetic thin plate may be further provided between the first magnet and the first diaphragm.

According to the electromagnetic electroacoustic transducer, the second
Since the AC magnetic flux can be made to flow efficiently on the diaphragm, the AC driving force can be increased and the sound pressure can be increased.

The diameter of the center pole may change in the height direction.

The diameter of the center pole may change so as to draw a quadratic curve with the height of the center pole as a variable.

According to the electromagnetic electro-acoustic transducer, it is possible to reduce the change in the magnetic resistance of the magnetic path due to the position of the diaphragm.

The thickness of the inner peripheral portion of the second diaphragm may be larger than the thickness of the outer peripheral portion of the second diaphragm.

The second diaphragm may have a rising or falling shape in which the cross section of the inner peripheral edge is substantially L-shaped.

According to the electromagnetic electro-acoustic transducer, the opposing area between the center pole and the second diaphragm is increased, so that the AC driving force generated in the second diaphragm can be increased.

[0021] A cover for covering the first hole provided in the second diaphragm may be further provided.

The cover may be integral with the first diaphragm.

According to the electromagnetic electro-acoustic transducer, it is possible to avoid a decrease in sound pressure due to air wraparound.

[0024] A second magnet may be further provided on the opposite side of the yoke with respect to the second diaphragm.

According to the electromagnetic electroacoustic transducer, the second
By arranging the magnets, the magnetic flux density generated in the second diaphragm by the first magnet can be suppressed, and more AC magnetic flux generated by the coil can flow into the second diaphragm. In addition, the static suction force generated in the second diaphragm is also canceled, and the first diaphragm can be in an equilibrium state.

[0026] A second magnetic thin plate provided on the opposite side of the yoke with respect to the second magnet may be further provided.

According to the electromagnetic electro-acoustic transducer, the second magnet can be operated efficiently, and the size of the second magnet can be reduced.

[0028] A first housing for supporting the first diaphragm may be further provided.

[0029] A second housing for supporting the second magnet may be further provided.

According to the present invention, there is provided a portable terminal device provided with the above-mentioned electromagnetic electro-acoustic transducer.

The portable terminal device may further include an antenna for receiving a radio wave and a transmission / reception circuit for converting the radio wave into an audio signal, and the electromagnetic electroacoustic transducer described above may reproduce the audio signal.

According to the present invention, a portable terminal device capable of reproducing an alarm sound, a melody sound, a voice, and the like can be realized.

In the electromagnetic electroacoustic transducer of the present invention,
The second diaphragm has a ring shape in which a hole is formed at the center, and the weight of the vibration system is reduced. further,
By forming the second diaphragm in a ring shape, the center pole does not contact the second diaphragm during vibration, so that the height of the center pole can be increased. As a result, the magnetic gap value is substantially smaller than that of the related art, and the driving force generated on the second diaphragm is increased. As a result, an electromagnetic electroacoustic transducer capable of reproducing high sound pressure and low frequency is realized.

[0034]

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

(Embodiment 1) FIG. 1 shows an electromagnetic electroacoustic transducer 1000 according to Embodiment 1 of the present invention.
(A), FIG. 1 (b), FIG. 1 (c), FIG. 1 (d) and FIG.

FIG. 1A is a sectional view of an electromagnetic electroacoustic transducer 1000 according to Embodiment 1 of the present invention. FIG. 2 is a magnetic flux vector diagram of the electromagnetic electroacoustic transducer 1000. The magnetic flux vector diagram shown in FIG. 2 shows only one half of the center axis of the electromagnetic electro-acoustic transducer 1000.

As shown in FIG. 1A, the electromagnetic electro-acoustic transducer 1000 is disposed so as to cover a cylindrical first housing 7 and a bottom surface of the first housing 7. A yoke 6 having a disc shape is provided, and 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 first magnet 5 is provided on the outer periphery of the coil 4, and an appropriate interval is provided over the entire periphery between the coil 4 and the inner peripheral surface of the first magnet 5. Further, the outer peripheral surface of the first magnet 5 and the inner peripheral surface of the first housing 7 are provided with an appropriate interval over the entire circumference. A first diaphragm 1, which is a ring-shaped nonmagnetic material as shown in a plan view in FIG. 1B, is supported on the upper end of the first housing 7 so as to be able to vibrate. An appropriate space is provided between the diaphragm 1 and the coil 4 and the center pole 3. In the center of the first diaphragm 1, a second diaphragm 2, which is an annular magnetic body, is provided concentrically with the first diaphragm 1.
The second diaphragm 2 has a hole at the center as shown in a plan view in FIG. A cover 13 (FIG. 1A) is provided at a central portion of the second diaphragm 2 so as to cover a hole formed in the second diaphragm 2. The center pole 3 has a shape that can be inserted into a hole formed in the second diaphragm 2.

An annular first magnetic thin plate 11 as shown in a plan view in FIG. 1D is provided on the surface of the first magnet 5 facing the first diaphragm 1. .
A concave portion for providing the first magnetic thin plate 11 is provided on an inner peripheral side portion of the first magnet 5. In the yoke 6, a plurality of air holes 8 communicating the space between the first diaphragm 1 and the yoke 6 and the outside of the space are provided at appropriate intervals in the circumferential direction. Each air hole 8 is provided in order to discharge air in the space between the first diaphragm 1 and the yoke 6 to the outside and reduce the acoustic load applied to the first diaphragm 1.

In the present embodiment, PEN (polyethylene naphthalate), which is a non-magnetic material, is used as the material of the first diaphragm 1, and its thickness is, for example, 38 μm. Permalloy is used as the material of the second diaphragm 2, and its thickness is, for example, 50 μm. The upper surface of the center pole 3 and the upper surface of the second diaphragm 2 are at the same height. The height of the upper surface of the center pole 3 may be higher than the lower surface of the second diaphragm 2.

The operation and effect of the electromagnetic electro-acoustic transducer 1000 configured as described above will be described.

In this embodiment, in the initial state where no current flows through the coil 4, as shown in FIG. 2, the first magnet 5, the first magnetic thin plate 11, the second diaphragm 2, the center The pole 3 and the yoke 6 form a first magnetic path. In the present embodiment, since the first diaphragm 1 is made of a resin material that is a nonmagnetic material,
In FIG. 2, the first diaphragm 1 is not shown.

In such a configuration, the second diaphragm 2
Above, a downward static suction force acts, and the second diaphragm 2 and the first diaphragm 1 (FIG. 1A) are displaced.

Next, when an AC current flows through the coil 4, an AC magnetic field is generated, 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 is displaced from the initial state together with the fixed first diaphragm 1. Vibration due to the displacement is radiated as sound.

In the electromagnetic electroacoustic transducer 1000, the second
The center pole 3 is provided so as to penetrate a hole at the center of the diaphragm 2 (in order to make the peak of the AC driving force generated in the second diaphragm 2 substantially coincide with the zero point, the center pole 3 is required). 3 and the upper surface of the second diaphragm 2 are preferably the same height), so that the second diaphragm 101 in the conventional electromagnetic electroacoustic transducer 200 shown in FIG. Compared with the magnetic gap between the center poles 103, the gap between the second diaphragm 2 and the center pole 3 in the first magnetic path of the electromagnetic electro-acoustic transducer 1000 shown in FIGS. The magnetic gap is narrow. Thereby, in the electromagnetic electro-acoustic transducer 1000, the magnetic resistance of the entire first magnetic path is reduced. Therefore, in the electromagnetic electro-acoustic transducer 1000, the rate at which the AC driving force decreases is smaller than in the conventional electromagnetic electro-acoustic transducer 200.
As a result, in the electromagnetic electroacoustic transducer 1000, even if the distance between the first magnet 5 and the second diaphragm 2 is increased in order to increase the amplitude range, a sufficient sound pressure can be obtained. It is possible to secure an AC driving force. Also the second
By making the diaphragm 2 of the ring annular, the mass of the vibration system is reduced,
Further, improvement in sound pressure is promoted.

In this embodiment, the second diaphragm 2
The cover 13 covers the hole of the center pole 3 and the second
Sound is completely radiated from between the vibration plate 2 and the vibration plate 2. However, the center pole 3 and the second diaphragm 2
When the sound between the center pole 3 and the second diaphragm 2 is substantially blocked by the relationship between the gap between the center pole 3 and the air hole 8, the cover 13 may not be provided. Further, the cover 13 may be integrally formed as a part of the first diaphragm 1, or may be an independent part.

In this embodiment, a resin material is used for the first diaphragm 1 because it is easy to mold, but a metal material (for example, titanium) may be used from the viewpoint of heat resistance. Further, a magnetic body may be used as the first diaphragm 1. Further, the first diaphragm 1 may have a disk shape.

In the present embodiment, the first magnetic thin plate 11 is provided on the first magnet 5. However, when a sufficient AC driving force can be obtained only by the first magnet 5, In the case where it is difficult to install, it may not be provided.

In this embodiment, the center pole 3
Is constant, but the diameter in the height direction may be changed. As an example, FIG. 3 shows a cross-sectional view of an electromagnetic electroacoustic transducer 1001 including a center pole 3 ′ whose diameter in the height direction decreases as approaching the yoke 6. The components of the electromagnetic electro-acoustic transducer 1001 are the same as those of the electro-magnetic electro-acoustic transducer 1000 except for the center pole 3 '.
(A)) is common.

In the electromagnetic electroacoustic transducer 1001, the second
As the diaphragm 2 is displaced downward, the magnetic gap between the second diaphragm 2 and the center pole 3 'increases, so that the decrease in AC driving force due to magnetic saturation as shown in FIG. 13 is reduced. can do. Further, as shown in FIG. 3, the shape of the change in the diameter of the center pole 3 ′ in the height direction may be a quadratic curve with the height as a variable.

(Embodiment 2) FIG. 4 shows an electromagnetic electroacoustic transducer 2000 according to Embodiment 2 of the present invention.
This will be described with reference to (a), FIG. 4 (b) and FIG.

FIGS. 4A and 5 are a sectional view and a magnetic flux vector diagram of an electromagnetic electroacoustic transducer 2000 according to the second embodiment. The magnetic flux vector diagram shown in FIG. 5 shows only one half with respect to the center axis of the electromagnetic electroacoustic transducer 2000.

In the electromagnetic electro-acoustic transducer 2000 shown in FIG. 4A, an annular second magnet 9 as shown in a plan view in FIG. It is provided with a magnetic gap. The second magnet 9 is supported by the second housing 10,
The second housing 10 is provided with a hole 12 for radiating sound from the first and second diaphragms 1 and 2 and the cover 13 to the outside of the second housing 10. Further, the second magnet 9 is magnetized in the height direction like the first magnet. Other configurations are the same as those of the electromagnetic electro-acoustic transducer 1000 shown in FIG.

The operation and effects of the electromagnetic electroacoustic transducer 2000 configured as described above will be described.

As shown in FIG. 5, the first magnet 5,
The first magnetic path is formed by the first magnetic thin plate 11, the second diaphragm 2, the center pole 3, and the yoke 6 as in the first embodiment (FIG. 2). Further, in the present embodiment, a second magnetic path is formed by the second magnet 9 and the second diaphragm 2.

In the initial state in which no current flows through the coil 4, on the second diaphragm 2, a downward static attractive force generated by the first magnetic path and an upward static attractive force generated by the second magnetic path. The power is canceling. Therefore, the first diaphragm 1 is hardly displaced by the first magnetic path.

Next, when an AC current flows through the coil 4, an AC magnetic field is generated, and an AC driving force is generated on the second diaphragm 2. Due to this AC driving force, the second diaphragm 2 is displaced from the initial state together with the fixed first diaphragm 1. Vibration due to the displacement is radiated as sound.

FIG. 6 shows the static attraction generated on the second diaphragm 2 with and without the second magnet 9. The vertical axis indicates the static suction force, and the horizontal axis indicates the distance from the zero point of the second diaphragm 2. The zero point indicates the position of the second diaphragm 2 when the vertical static attraction acting on the second diaphragm 2 by the first magnet 5 and the second magnet 9 is balanced. The solid line indicates the case where the second magnet 9 is provided, and the broken line indicates the case where the second magnet 9 is not provided.

In FIG. 6, when the second magnet 9 is not provided, the value of the static attraction force is always positive because the second diaphragm 2 is attracted by the first magnet 5.

On the other hand, when the second magnet 9 is provided,
Static attraction also occurs in the direction opposite to the first magnet 5. Therefore, the value of the static suction force can be both positive and negative with respect to the zero point at which the static suction force is balanced in the second diaphragm 2.

In the present embodiment, the thickness of the second diaphragm 2 is reduced to 50 μm to facilitate the occurrence of magnetic saturation, so that the second diaphragm 2 is rapidly abruptly moved toward the first magnet 5. The phenomenon that the target suction force is increased can be suppressed. With such a configuration, the change in the static suction force has a substantially linear characteristic with respect to the distance from the zero point as shown in FIG.

As a result, it is possible to reduce the stiffness of the entire system obtained from the difference between the elastic force of the first diaphragm 1 and the static suction force, and lower the resonance frequency determined by the stiffness. be able to.

If the elastic force characteristic of the first diaphragm 1 and the static suction force characteristic are similar (that is, the first diaphragm 1
If the elastic force is linear), the stiffness of the entire system is constant regardless of the distance, so that the resonance frequency does not change due to the applied voltage, and the harmonic distortion is small.

FIG. 7 shows the AC driving force generated on the second diaphragm 2 with and without the second magnet 9. The vertical axis indicates the AC driving force, and the horizontal axis indicates the distance from the first magnet 5. Similar to FIG. 6, the solid line indicates the case where the second magnet 9 is provided, and the broken line indicates the case where the second magnet 9 is not provided.

When the second magnet 9 is not provided in FIG. 7, magnetic saturation occurs due to the use of the second diaphragm 2 having a small thickness, and a sufficient AC driving force cannot be obtained.

Then, the second magnet 9 is added,
The magnetic flux generated in the second diaphragm 2 is canceled by the magnet 5 to mitigate the magnetic saturation. As a result, the AC magnetic flux as the driving force can efficiently flow into the second diaphragm 2, and the obtained AC driving force increases. In other words, a sufficient AC driving force can be obtained even with a thin diaphragm that easily causes magnetic saturation. Also, by reducing the thickness, the weight of the vibration system is reduced, so that the reproduced sound pressure can be further increased.

In the present embodiment, the thickness of the second diaphragm 2 is reduced to 50 μm so as to easily cause magnetic saturation. However, the thickness may be increased without considering magnetic saturation. In this case, since the AC driving force does not decrease due to magnetic saturation near the first magnet shown in FIG.
Is effective when used near the first magnet.
A similar effect can be obtained by using a material having a large saturation magnetization such as pure iron as the material of the second diaphragm 2.

In the present embodiment, the second housing 10 is provided to support the second magnet 9. However, when the electromagnetic electroacoustic transducer 2000 is attached to, for example, a mobile phone, The second magnet 9 may be embedded on the side of the housing to share the housing between the electromagnetic electro-acoustic transducer 2000 and the mobile phone.

(Embodiment 3) FIG. 8 shows an electromagnetic electroacoustic transducer 3000 according to Embodiment 3 of the present invention.
This will be described with reference to FIG. 8A, FIG. 8B and FIG.

FIGS. 8A and 9 are a sectional view and a magnetic flux vector diagram of an electromagnetic electroacoustic transducer 3000 according to the third embodiment. The magnetic flux vector diagram shown in FIG. 9 shows only one half with respect to the center axis of the electromagnetic electro-acoustic transducer 3000.

The electromagnetic electroacoustic transducer 3000 shown in FIG. 8A has a second diaphragm 2 having an L-shaped cross section.
2, an annular second magnet 29 provided with a magnetic gap above the second diaphragm 22, and FIG. 8B provided above the second magnet 29 as a plan view. And an annular second magnetic thin plate 24 as shown. The second magnet 29 is supported by the second housing 20, and the second housing 20 is provided with a recess for accommodating the second magnetic thin plate 24. Further, the second housing 20 is provided with a plurality of air holes 32 for radiating sounds from the first diaphragm 1 and the second diaphragm 22 to the outside of the second housing 20. . Other configurations are the same as those of the electromagnetic electro-acoustic transducer 2000 according to the second embodiment of the present invention shown in FIG.

By providing the second magnetic thin plate 24 on the upper surface of the second magnet 29, as shown in FIG. 9, the second magnetic path is formed by the second magnet 29 and the second magnetic thin plate 24. And the second diaphragm 22.
The effect of the first magnet 5 and the second magnet 29 is the same as that of the first magnet 5 and the second magnet 9 (FIG. 4A) described in the second embodiment.
The magnetic flux of the second magnet 29 is guided to the second magnetic thin plate 24, and the energy product is adjusted to form an appropriate magnetic path.

The sectional shape of the second diaphragm 22 is shown in FIG.
Since it is an L-shape as shown in FIG.
The magnetic flux concentrates on the inner peripheral edge of the second diaphragm 2, and the magnetic flux can be efficiently guided between the second diaphragm 22 and the center pole 3. The cross-sectional shape of the second diaphragm 22 is the same as that of the second diaphragm 22.
Any shape may be used so long as the thickness of the inner peripheral edge is larger than the thickness of the outer peripheral edge. For example, the cross-sectional shape may be triangular or trapezoidal. Alternatively, two or more diaphragms having different outer diameters may be laminated to form the second diaphragm 22. Also,
By increasing the inner peripheral edge of the second diaphragm 22, the facing area between the second diaphragm 22 and the center pole 3 increases, so that the air between the second diaphragm 22 and the center pole 3 increases. The resistance can be increased. In this case, the cover 13 can be omitted from the electromagnetic electroacoustic transducer 3000.

As shown in FIG. 8A, by providing the second magnetic thin plate 24, since the magnetic flux of the second magnet 29 is guided by the second magnetic thin plate 24,
The magnetic resistance of the magnetic path becomes smaller. Therefore, compared to the case where the second magnetic thin plate 24 is not provided, the second magnet 2
9 can be reduced. Further, the magnetic flux of the second magnet 29 is applied to the second magnetic thin plate 2.
4 to be guided into the electromagnetic electroacoustic transducer 3000
The leakage flux to the outside is reduced.

The electromagnetic electro-acoustic transducer 30 of the present embodiment
00, the second magnetic thin plate 24 is not provided (for example, the electromagnetic electroacoustic transducer 200 shown in FIG.
0), the second magnet 9 has an energy product of 26M.
By providing the second magnetic thin plate 24, the second magnetic thin plate 24 is used to obtain an energy product of 22 MGOe and a 0.5 mm-thick second GOE.
Of the magnet 29.

The first diaphragm 1 provided in each of the electromagnetic electro-acoustic transducers 1000, 1001, 2000 and 3000 described in the first to third embodiments has a part of an annular shape perpendicular to the diameter direction. The shape is raised in various directions. However, the first diaphragm 1 is not limited to such a shape, and may have a flat cross-sectional shape.

(Embodiment 4) As Embodiment 4 of the present invention, a portable telephone 61 which is an example of a portable terminal equipped with the electromagnetic electro-acoustic transducer of the present invention will be described with reference to FIGS. 10 and 11. I do.

FIG. 10 is a partially cutaway perspective view of portable telephone 61 according to Embodiment 4 of the present invention. FIG. 11 is a block diagram showing a schematic configuration of the mobile phone 61.

The portable telephone 61 is a portable telephone housing 62.
And a sound hole 63 provided in the housing 62 and an electromagnetic electro-acoustic transducer 64. As the electromagnetic electro-acoustic transducer 64 provided in the mobile phone 61, the electromagnetic electro-acoustic transducer 100 described in Embodiments 1, 2, and 3 of the present invention is used.
Any of 0, 1001, 2000 and 3000 applies. Electromagnetic electroacoustic transducer 6 inside housing 62
4 is provided so that the diaphragm faces the sound hole 63.

As shown in FIG. 11, the portable telephone 61
It further includes an antenna 150, a transmission / reception circuit 160, a call signal generation circuit 161, and a microphone 152. The transmission / reception circuit 160 includes a demodulation unit 160a, a modulation unit 16
0b, a signal switching section 160c and an answering section 160d.

The antenna 150 is used for receiving radio waves output from the nearest base station and transmitting radio waves to the base station. Demodulation section 160a decodes the modulated wave input from antenna 150, converts the modulated wave into a received signal, and outputs the received signal to signal switching section 160c. Signal switching unit 160
c is a circuit for switching signal processing according to the content of the received signal. If the received signal is an incoming signal, it is output to the call signal generating circuit 161; if it is a voice signal, it is output to the electromagnetic electro-acoustic transducer 64; if it is a voice-recorded voice signal, it is output to the voice-recording unit 160d. . Answering machine 160d
Is composed of, for example, a semiconductor memory (not shown). The message recording message at power-on is stored in the message recording unit 160d, but when the mobile phone 61 is out of the service area or when the power is turned off, the message recording message is stored in the storage device of the base station. The call signal generation circuit 161 generates a call signal and outputs the signal to the electromagnetic electro-acoustic transducer 64.

As in the case of the conventional mobile phone, the mobile phone 6
1 has a small microphone 15 as an electroacoustic transducer.
2 are provided. Modulating section 160 b modulates the dial signal and the audio signal converted by microphone 152 and outputs the result to antenna 150.

The operation of the portable telephone 61 as a portable terminal having such a configuration will be described.

The radio wave output from the base station is
0 and is demodulated into a baseband received signal by the demodulation unit 160a. When detecting that the received signal is an incoming signal, the signal switching circuit 160c notifies the incoming call to the mobile phone 6.
In order to notify the first user, an incoming signal is output to the call signal generating circuit 161.

Receiving such an incoming signal, calling signal generating circuit 161 outputs a calling signal. The ringing signal includes a signal of a pure tone in the audible band or a complex sound thereof, and when the ringing signal is input to the electromagnetic electroacoustic transducer 64, the electromagnetic electroacoustic transducer 64 outputs a ring tone to the user.

When the user enters the receiving state, the signal switching unit 1
After adjusting the level of the received signal, 60c directly outputs the received audio signal to the electroacoustic transducer 64. The electromagnetic electroacoustic transducer 64 operates as a receiver or a speaker, and reproduces an audio signal.

The user's voice is detected by the microphone 152, converted into a voice signal, and input to the modulator 160b. The audio signal is modulated by the modulation section 160b, converted into a predetermined carrier, and output from the antenna 150.

When the user of the portable telephone 61 sets the absence recording mode while the power is on, the contents of the transmission are stored in the absence recording section 160d. Also mobile phone 61
When the user has turned off the power, the transmission contents are temporarily stored in the base station. Then, when the user requests the reproduction of the absence recording by key operation, the signal switching unit 160c receives the request and acquires the recording message from the absence recording unit 160d or the base station. Then, the audio signal is adjusted to a loud sound level and output to the electromagnetic electro-acoustic transducer 64.
At this time, the electromagnetic electro-acoustic transducer 64 operates as a receiver or a speaker, and outputs a message.

Many of the electromagnetic electro-acoustic transducers built in portable terminals typified by conventional portable telephones have high resonance frequencies and have been used only for ringing tone reproduction.

However, since the electromagnetic electro-acoustic transducer of the present invention can lower the resonance frequency, if the electro-magnetic electro-acoustic transducer of the present invention is used in a portable terminal, a voice signal can be reproduced and a ringing tone can be reproduced. Both reproduction and audio signal reproduction can be performed by one electromagnetic electro-acoustic transducer.
As a result, it is possible to reduce the number of acoustic components built in the portable terminal.

In the portable telephone 61, the electromagnetic electroacoustic transducer 64 is mounted directly on the housing 62, but may be mounted on a substrate built in the portable telephone 61. Also, an acoustic port may be added to increase the sound pressure of the ringing tone.

10 and 11, a portable telephone is shown as an example of a portable terminal. However, the present invention is not limited to this. For example, a pager, a notebook computer, a wristwatch, etc.
The present invention is applied to a portable terminal equipped with an electromagnetic electro-acoustic transducer.

Note that in Embodiments 2 and 3,
Although the second housings 10 and 20 for supporting the second magnets 9 and 29 are provided, the electromagnetic electroacoustic transducers 2000 and 300 in the second and third embodiments are provided.
For example, when attaching 0 to the mobile phone 61 shown in FIG. 10, the second magnets 9 and 29 are embedded in the housing 62 of the mobile phone, and the second housings 10 and 20 are replaced with the housing 62 of the mobile phone. May be. Further, the second magnetic thin plate 24 in the electromagnetic electroacoustic transducer 3000 may be provided in the housing 62 in the same manner.

[0093]

According to the electromagnetic electro-acoustic transducer of the present invention, a hole is formed in the center of the second diaphragm, and the center pole is disposed so as to penetrate the hole.
The distance between the second diaphragm forming the magnetic path and the center pole can be made smaller than before. As a result, the first
A sufficient driving force can be obtained to make the vibration plate of this type have a large amplitude, and high sound pressure reproduction becomes possible.

Further, according to the electromagnetic electro-acoustic transducer of the present invention, by providing the first magnetic thin plate on the surface of the first magnet facing the first diaphragm, the second diaphragm can be provided on the first magnet. An AC magnetic flux can flow efficiently. For this reason, the AC driving force increases and the sound pressure can be increased.

According to the electromagnetic electroacoustic transducer of the present invention, the first diaphragm is equilibrated by disposing the second magnet above the second diaphragm with a magnetic gap interposed therebetween. The AC driving force that acts on the second diaphragm while holding it can be increased. Further, since the static suction force and the displacement characteristics of the first diaphragm have a substantially linear relationship, high sound pressure and low distortion reproduction can be performed without changing other components. Further, by providing the second magnetic thin plate above the second magnet, the second magnet can be made to act efficiently, and the shape of the second magnet can be reduced.

Further, according to the portable terminal device of the present invention, by incorporating the electromagnetic electro-acoustic transducer of the present invention, a portable terminal device capable of reproducing an alarm sound, a melody sound, a voice, and the like can be realized. .

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention. FIG. 1B is a first vibration of the electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention. (C) is a plan view of a second diaphragm of the electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention. (D) is an electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention. Plan view of the first magnetic thin plate of the container

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

FIG. 3 is a cross-sectional view of the electromagnetic electro-acoustic transducer according to the first embodiment of the present invention.

FIG. 4A is a cross-sectional view of an electromagnetic electro-acoustic transducer according to Embodiment 2 of the present invention. FIG. 4B is a second magnet of the electromagnetic electro-acoustic transducer according to Embodiment 2 of the present invention. Top view of

FIG. 5 is a magnetic flux vector diagram of the electromagnetic electroacoustic transducer according to Embodiment 2 of the present invention.

FIG. 6 is a diagram showing characteristics of a static attractive force generated on a second diaphragm of the electromagnetic electro-acoustic transducer according to Embodiment 2 of the present invention.

FIG. 7 is a diagram showing an AC driving force characteristic generated on a second diaphragm of the electromagnetic electro-acoustic transducer according to Embodiment 2 of the present invention.

8A is a cross-sectional view of an electromagnetic electro-acoustic transducer according to Embodiment 3 of the present invention. FIG. 8B is a cross-sectional view of a second magnet of the electromagnetic electro-acoustic transducer according to Embodiment 3 of the present invention. Plan view of body thin plate

FIG. 9 is a magnetic flux vector diagram of the electromagnetic electroacoustic transducer according to the third embodiment of the present invention.

FIG. 10 is a partially cutaway perspective view of a mobile phone including an electromagnetic electro-acoustic transducer according to Embodiment 4 of the present invention.

FIG. 11 is a block diagram of a mobile phone including an electromagnetic electro-acoustic transducer according to Embodiment 4 of the present invention.

12A is a plan view of a conventional electromagnetic electro-acoustic transducer, and FIG. 12B is a cross-sectional view of the conventional electromagnetic electro-acoustic transducer.

FIG. 13 is a diagram showing a driving force characteristic generated on a second diaphragm in a conventional electromagnetic electro-acoustic transducer.

[Explanation of symbols]

 1, 100 First diaphragm 2, 22, 101 Second diaphragm 3, 3 ', 103 Center pole 4, 104 Coil 5, 105 First magnet 6, 106 Yoke 7, 107 First housing 9 , 29 Second magnet 10, 20 Second housing 11 First magnetic thin plate 13 Cover 24 Second magnetic thin plate

Claims (16)

[Claims] A first diaphragm, a second diaphragm which is provided at a center of the first diaphragm, and is a magnetic body having a first hole formed in a central portion thereof, A yoke provided to face the diaphragm, a center pole provided on the first diaphragm side with respect to the yoke, and having a shape insertable into the first hole; And a first magnet disposed so as to surround the coil. 2. The electromagnetic electro-acoustic transducer according to claim 1, wherein the first diaphragm has a second hole into which the center pole can be inserted. 3. The electromagnetic electro-acoustic transducer according to claim 1, wherein the height of the upper surface of the center pole is higher than the lower surface of the second diaphragm. 4. The apparatus according to claim 1, further comprising a first magnetic thin plate provided between the first magnet and the first diaphragm.
The electromagnetic electro-acoustic transducer according to claim 1. 5. The electromagnetic electro-acoustic transducer according to claim 1, wherein a diameter of the center pole changes in a height direction. 6. The electromagnetic electro-acoustic transducer according to claim 5, wherein the diameter of the center pole changes so as to draw a quadratic curve with the height of the center pole as a variable. 7. The thickness of the inner peripheral edge of the second diaphragm is greater than the thickness of the outer peripheral edge of the second diaphragm.
2. The electromagnetic electro-acoustic transducer according to claim 1. 8. The electromagnetic electro-acoustic transducer according to claim 1, wherein the second diaphragm has a rising or falling shape in which a cross section of an inner peripheral portion is substantially L-shaped. 9. The first diaphragm provided on the second diaphragm.
2. The electromagnetic electro-acoustic transducer according to claim 1, further comprising a cover for covering said hole. 10. The electromagnetic electro-acoustic transducer according to claim 9, wherein the cover is integral with the first diaphragm. 11. The electromagnetic electro-acoustic transducer according to claim 1, further comprising a second magnet provided on the opposite side of the yoke with respect to the second diaphragm. 12. The electromagnetic electro-acoustic transducer according to claim 11, further comprising a second magnetic thin plate provided on the opposite side of the yoke with respect to the second magnet. 13. The electromagnetic electro-acoustic transducer according to claim 1, further comprising a first housing that supports the first diaphragm. 14. A second magnet supporting the second magnet.
The electromagnetic electro-acoustic transducer according to claim 11, further comprising: a housing. 15. A portable terminal device comprising the electromagnetic electro-acoustic transducer according to claim 1. 16. The mobile terminal according to claim 15, further comprising an antenna for receiving a radio wave, and a transmission / reception circuit for converting the radio wave into an audio signal, wherein the electromagnetic electroacoustic transducer reproduces the audio signal. apparatus.