JP2002176694A - Electromagnetic electro-acoustic transducer and mobile terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that conventionally acoustic characteristics cannot be obtained with an electromagnetic electro-acoustic transducer reproduce sound. SOLUTION: The electromagnetic electro-acoustic transducer of this invention is provided with a magnetic body, a suspension that fixed the magnetic body in the middle to support it, a diaphragm connected to the suspension, a magnet to generate a DC magnetic flux to the magnetic body and a coil to generate an AC magnetic flux to the magnetic body. Thus, this invention provides the electromagnetic electroacoustic transducer, that has proper acoustic characteristics and high reliability. Furthermore, the mobile terminal of this invention is provided with the electromagnetic electroacoustic transducer. Thus, the mobile terminal employing the one electromagnetic electroacoustic transducer that reproduces alarm tones, melody tones and voice is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on a portable terminal device such as a portable telephone and a pager (registered trademark).
The present invention relates to an electromagnetic electro-acoustic transducer used for reproducing an alarm sound, a melody sound and a voice at the time of an incoming call, and a portable terminal device equipped with the electromagnetic electro-acoustic transducer.

[0002]

2. Description of the Related Art FIGS. 9A and 9B are a plan view and a cross-sectional view of a conventional electromagnetic electroacoustic transducer 2000. FIG.

A conventional electromagnetic electro-acoustic transducer 2000 is
The housing includes a cylindrical housing 107 and a disk-shaped yoke 106 disposed so as to cover the bottom surface of the housing 107. A center pole 103 integrally formed with the yoke is provided at the center of the yoke 106. ing. A coil 104 is wound around the center pole 103. 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 diaphragm 100 is supported on the upper end of the housing 107, and an appropriate gap is provided between the diaphragm 100 and the magnet 105, the coil 104, and the center pole 103. On the diaphragm 100, a disk-shaped magnetic body 101 is provided concentrically with the diaphragm 100.

[0004] The operation of the electromagnetic electroacoustic transducer 2000 will be described below.

In an initial state in which no current flows through the coil 104, a magnetic path is formed by the magnet 105, the magnetic body 101, the center pole 103, and the yoke 106.
The magnetic body 101 includes a magnet 105 and a center pole 10.
It is sucked to the third side and displaced until it becomes equal to the elastic force of the diaphragm 100. In such an initial state, the coil 104
When an AC current flows through the magnetic body 101, an AC magnetic field is generated in the magnetic path, and an AC driving force is generated in the magnetic body 101. When such an AC driving force is generated in the magnetic body 101, the magnetic body 101 is fixed by the interaction between the static attraction force generated by the magnet 105 and the AC driving force.
Displaces with the initial state. Vibration due to the displacement is radiated as sound.

[0006]

Generally, the lower limit of the reproduction frequency band of the electromagnetic electroacoustic transducer depends on the lowest resonance frequency of the vibration system. Here, the vibration system refers to an element of the electromagnetic electroacoustic transducer that actually vibrates to generate sound. In the conventional electromagnetic electro-acoustic transducer 2000, the lowest resonance frequency could not be lowered until a low frequency such as voice could be reproduced. The reason will be described below.

The lowest resonance frequency of the electromagnetic electroacoustic transducer 2000 is determined by the elastic force of the diaphragm 100 and the magnet 1
05 depends on the stiffness of the entire vibration system obtained as a difference from the static attractive force generated on the magnetic body 101.

FIG. 10 shows a relationship between a force-displacement curve of the diaphragm 100 and a static attractive force generated on the magnetic body 101 by the magnet 105. The vertical axis is force, and the horizontal axis is diaphragm 100
Shows the displacement of The intersection A between the force-displacement curve of the diaphragm 100 and the curve indicating the static attraction generated on the magnetic body 101 by the magnet 105 indicates a point where the elastic force of the diaphragm 100 and the static attraction balance. . The lowest resonance frequency is
It depends on the difference between the elastic force of the diaphragm 100 and the static suction force with the balanced intersection A as the origin.

In order to lower the lowest resonance frequency, it is necessary to reduce the elastic constant of diaphragm 100. However, the elastic constant of diaphragm 100 is made too small (that is, intersection A
Is removed), the magnetic body 101 is attracted to the center pole 103 together with the diaphragm 100. That is, since the elastic constant must be within the range where the intersection A exists, the lowest resonance frequency that can be designed is naturally determined. As a result of these restrictions, the conventional electromagnetic electro-acoustic transducer 2000 often has a minimum resonance frequency of about 2.5 kHz or more. For this reason, the conventional electromagnetic electroacoustic transducer 2000 cannot reproduce low-frequency components such as voice.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an electromagnetic electro-acoustic transducer capable of reproducing low-frequency frequencies such as voice and providing good acoustic characteristics and a portable terminal equipped with the same. I do.

[0011]

The electromagnetic electro-acoustic transducer of the present invention comprises a magnetic material, a suspension for fixing and supporting the magnetic material at the center, a diaphragm connected to the suspension, and a magnetic material. In addition, a magnet for generating a DC magnetic flux and a coil for generating an AC magnetic flux in the magnetic body are provided, thereby achieving the above object.

According to the above feature, a highly reliable electromagnetic electroacoustic transducer having good acoustic characteristics can be obtained.

The suspension may have a greater stiffness value in the vibration direction than the diaphragm.

[0014] The magnet may be arranged so as to surround the coil.

[0015] The coil may further include a center pole provided on an inner peripheral side of the coil, and a yoke provided on a side of the coil opposite to the diaphragm.

The diaphragm may be made of resin.

[0017] The suspension may be metal.

[0018] The suspension may be a non-magnetic material.

According to the above feature, since the diaphragm and the suspension can be designed independently of each other, the degree of freedom in designing is increased.

A thin magnetic plate provided between the magnet and the diaphragm may be further provided.

According to the above feature, since the AC magnetic flux can be efficiently flowed on the magnetic material, the AC driving force is increased and the sound pressure can be increased.

A hole may be formed in the center of the magnetic body.

[0023] A cover for covering the hole may be further provided.

According to the above feature, it is possible to avoid a decrease in sound pressure due to a sound wraparound in the housing.

An electromagnetic electro-acoustic transducer according to the present invention comprises: a magnetic body; a suspension for fixing and supporting the magnetic body at the center; a diaphragm connected to the suspension; and a diaphragm opposed to the first diaphragm. A center pole provided on the diaphragm side with respect to the yoke,
A coil arranged to surround the center pole,
A hole disposed in the magnetic body and the suspension, wherein the center pole has a shape that can be inserted into the hole, and a height of an upper surface of the center pole is provided. Is not less than the lower surface of the magnetic body, thereby achieving the above object.

According to the above feature, a stable AC driving force can be obtained because the distance between the center pole and the diaphragm can be kept substantially constant even at the time of amplitude.

The suspension and the magnetic body may be integrated.

The outer peripheral portion of the diaphragm and the outer peripheral portion of the suspension may be on the same plane.

According to the above feature, the number of parts can be reduced and the number of assembling steps can be reduced, and the assembling accuracy can be improved.

A portable terminal device according to the present invention includes the electromagnetic electroacoustic transducer described above.

According to the above feature, a portable terminal device that reproduces an alarm sound, a melody sound, and a voice with one electromagnetic electro-acoustic transducer can be realized.

[0032]

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

(Embodiment 1) An electromagnetic electroacoustic transducer 1000 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG.

FIG. 1 is a sectional view of an electromagnetic electro-acoustic transducer 1000. The electromagnetic electro-acoustic transducer 1000 includes a disk-shaped yoke 6 and a cylindrical housing 7 surrounding the disk-shaped yoke 6.
And a center pole 3 provided at the center of the yoke 6
And a coil 4 wound around a center pole 3, an annular magnet 5 provided on the outer periphery of the coil 4, a suspension 1 oscillated by a housing 7, and a center portion of the suspension 1. Magnetic body 2, cylindrical spacer 10 provided on housing 7, and spacer 1
And a vibrating plate 9 supported so as to be able to vibrate by zero.

The center of the diaphragm 9 is connected to the suspension 1. The coil 4 and the inner peripheral surface of the magnet 5 are provided with an appropriate interval over the entire circumference. Also, the outer peripheral surface of the magnet 5 and the inner peripheral surface of the housing 7 are appropriately spaced over the entire circumference. Coil 4, center pole 3
An appropriate distance is provided between the magnet 5 and the suspension 1. A diaphragm 9 is provided on the bottom of the housing 7.
A plurality of air holes 8 for discharging air in the space between the diaphragm 9 and the yoke 6 to the outside in order to reduce the acoustic load applied to the air conditioner are formed.

As shown in the plan view of FIG. 2, the magnetic body 2 has a disk shape. As shown in FIG. 3 as a plan view, the suspension 1 includes a central portion 31 provided with the magnetic body 2, an outer peripheral portion 32 supported by the housing 7, a central portion 31 and an outer peripheral portion 3.
2 and a plurality of radially-shaped portions 33 connecting the two. As shown in FIG. 1, the diaphragm 9 has a cone shape having a down-roll shape around it. Vibration direction 3 of suspension 1
The stiffness of 0 is larger than the stiffness of the diaphragm 9 in the vibration direction 30.

In this embodiment, the material of the suspension 1 is stainless steel, the material of the magnetic body 2 is Permalloy, and the material of the diaphragm 9 is PEN (Poly Et).
(Hyrene Naphthalate).

The electromagnetic electro-acoustic transducer 100 as described above
For 0, its operation will be described.

In the initial state where no current flows through the coil 4,
Magnet 5, magnetic body 2, center pole 3, yoke 6
This forms a magnetic path. Due to this magnetic path, a downward static attraction force acts on the magnetic body 2, and the suspension 1 is displaced downward together with the magnetic body 2. Accordingly, the diaphragm 9 connected to the suspension 1 is also displaced downward. 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 magnetic body 2. With this AC driving force, the magnetic body 2 moves the suspension 1 and the diaphragm 9
Fluctuates from the initial state. The vibration of the diaphragm 9 caused by the fluctuation is radiated as sound.

In the electromagnetic electro-acoustic transducer 1000,
The stiffness of the suspension 1 in the vibration direction 30 is greater than the stiffness of the diaphragm 9 in the vibration direction 30. For example, the stiffness of the suspension 1 in the vibration direction 30 is designed to be 7 times larger than that of the diaphragm 9. Since the stiffness of the suspension 1 is large, the magnetic body 2 to which static attraction is constantly applied is substantially supported by the suspension 1. Conventional electromagnetic electroacoustic transducer 2
Unlike 000, diaphragm 9 does not need to support magnetic body 2.

Therefore, the shape of the diaphragm 9 can be freely designed without considering the support of the magnetic body 2. As a result, since the stiffness is unlikely to increase at the time of large amplitude unlike the conventional case, it is possible to design the lowest resonance frequency to be low (for example, 700 to 800 Hz), and it is possible to reproduce the low frequency band such as voice. I can do it.

When the diameter of the diaphragm 9 is, for example, 15 mm, the effective radius at which the diaphragm 9 actually vibrates is increased by 10% or more as compared with the case where the diaphragm 9 is designed in consideration of the support of the magnetic body 2. Therefore, the reproduction sound pressure can be improved.

In the electromagnetic electro-acoustic transducer 1000,
The suspension 1 does not need to perform the function of generating sound, and may be designed in consideration of only the support of the magnetic body 2. For this reason, as shown in FIG. 3, it can be realized by a flat plate, and the precision of parts is improved as compared with the conventional case where the diaphragm is formed to support the magnetic material on the diaphragm, and the performance of the product is improved. Can be reduced. Since the elastic force of the suspension 1 is designed to be larger than the static suction force, the magnetic body 2 is not attracted to the center pole 3 even if the elastic force of the diaphragm 9 is small.

The metal material such as stainless steel used as the material of the suspension 1 has almost no change with time due to the static suction force constantly acting on the magnetic body 2. By using a metal material such as stainless steel as the material of the suspension 1 which substantially supports the magnetic body 2, it is possible to realize a durable electromagnetic electro-acoustic transducer having almost no change over time.

Also, by using a non-magnetic or weak magnetic material for the material of the suspension 1, the suspension 1 is not affected by the static attraction force from the magnet 5, so that the shape design of the suspension 1 is further facilitated.

Since there is no need to consider the support of the magnetic body 2 for the diaphragm 9, the degree of freedom in designing the shape of the diaphragm 9 for obtaining desired acoustic characteristics is high. As described above, in addition to being able to reproduce a low frequency such as a sound by reducing the change in the stiffness due to the amplitude, it is also possible to design such that the distortion of the diaphragm 9 is reduced. Further, the vibration plate 9 can be designed so as to improve the flatness of the amplitude characteristic with respect to the input voltage. Thus, the diaphragm 9 can be freely designed so as to obtain good acoustic characteristics. P
Since resin materials such as EN are easy to process and mold,
The use of a resin material such as PEN as the material of the diaphragm 9 facilitates the design of the diaphragm 9 that provides good acoustic characteristics.

In this embodiment, the suspension 1
Stainless steel material and PEN for the diaphragm 9, but are not limited thereto. For example, if heat resistance is taken into consideration, a metal material may be used for both the suspension 1 and the diaphragm 9, or a metal material and a heat-resistant resin material may be used. In addition, although a non-magnetic material is used as the material of the suspension 1, a magnetic material may be used to increase the AC driving force, and a permalloy, which is the same material as the magnetic material 2, may be used in consideration of the joint surface. .

In this embodiment, the suspension 1
Has a radial shape in three directions, but may have another shape such as a butterfly shape. Further, the diaphragm 9 has a cone shape, but may have another shape such as a dome shape.

(Embodiment 2) An electromagnetic electro-acoustic transducer 1100 according to Embodiment 2 of the present invention will be described with reference to FIGS.

FIG. 4 is a sectional view of the electromagnetic electro-acoustic transducer 1100. In the electromagnetic electroacoustic transducer 1100,
The coil 4, the yoke 6, the housing 7, the air hole 8, and the spacer 10 are the same as those of the electromagnetic electro-acoustic transducer 1000 according to the first embodiment shown in FIG.

The electromagnetic electro-acoustic transducer 1100 is similar to that shown in FIG.
(A) As shown in plan views in FIGS. 5 (b) and 5 (c), a ring-shaped magnetic body 1 having a hole formed in the center.
2, a suspension 11 and a diaphragm 19, a center pole 13 having a shape insertable into the hole, a cover 20 covering the hole, and a magnet 2 having a recess.
5 and a magnetic thin plate 15 provided in a recess formed in the magnet 25. The height of the upper surface of the center pole 13 is higher than the lower surface of the magnetic body 12.

As in the first embodiment, the non-magnetic resin material PEN was used for the material of the diaphragm 19, and the magnetic material Permalloy was used for the suspension 11 as in the first embodiment.

The electromagnetic electro-acoustic transducer 110 as described above
For 0, its operation will be described.

In the initial state where no current flows through the coil 4,
A magnetic path is formed by the magnet 25, the magnetic thin plate 15, the magnetic material 12, the center pole 13, and the yoke 6,
A static suction force is generated on the magnetic body 12. When an AC current flows through the coil 4, an AC driving force is generated on the magnetic body 12 in addition to the static attractive force, and the diaphragm 19 vibrates.

In this embodiment, the magnetic thin plate 15 is provided on the magnet 25. Thus, the magnetic flux in the magnetic path can be efficiently guided to the magnetic body 12, and the magnetic resistance of the entire magnetic path can be reduced. Since the magnetic flux density in the magnetic body 12 increases, the AC driving force generated on the magnetic body 12 increases, and the sound pressure can be improved.

Further, in the present embodiment, the height of the center pole 13 is high, is substantially flush with the magnetic body 12, and the magnetic body 12 vibrates in a state where the center pole 13 passes through the center of the magnetic body 12. Center pole 13 and magnetic body 1
2 are substantially on the same plane, even if the amplitude range is large and the distance between the magnet 25 and the magnetic body 12 is large, the magnetic body 12 is smaller than the conventional electromagnetic electroacoustic transducer 1100 shown in FIG. The magnetic gap between the magnetic pole and the center pole 13 is narrow, and the magnetic resistance of the entire magnetic path is small. For this reason,
The AC driving force can be improved as compared with the conventional electromagnetic electro-acoustic transducer 1100. As a result, it is possible to secure an AC driving force for obtaining a sufficient sound pressure.
Further, the magnetic body 12, the suspension 11, and the diaphragm 19
Is annular, so that the mass of the vibration system is lightened, so that the sound pressure can be improved.

In this embodiment, the cover 20 covers the holes of the magnetic body 12, the suspension 11 and the diaphragm 19, so that sound is radiated from the gap between the center pole 13 and the magnetic body 12. However, the cover 20 need not be provided if the radiation of the sound from the gap is substantially blocked due to the relationship between the gap and the air hole 8. Further, in the present embodiment, the cover 20 is an independent component, but may be integrally formed as a part of the diaphragm 19.

In this embodiment, the magnet 25
Although the magnetic thin plate 15 is provided above, the magnetic thin plate 15 may not be provided when a sufficient AC driving force can be obtained only by the magnet or when the magnetic thin plate 15 is difficult to install due to space limitations.

Although the diameter of the center pole 13 is constant in this embodiment as shown in FIG. 4, the diameter of the center pole 13 may be changed in the height direction. For example, when the diameter is reduced as approaching the yoke 6, as the magnetic body 12 is displaced downward, the center pole 1 is displaced.
Since the magnetic gap with the magnetic material 12 is widened, it is possible to reduce a decrease in AC driving force due to magnetic saturation of the magnetic body 12.

(Embodiment 3) FIGS. 6 and 7 show an electromagnetic electroacoustic transducer 1200 according to Embodiment 3 of the present invention.
This will be described with reference to FIG.

FIG. 6 is a cross-sectional view of the electromagnetic electro-acoustic transducer 1200. In the electromagnetic electro-acoustic transducer 1200,
Coil 4, yoke 6, air hole 8, center pole 13,
The magnetic thin plate 15 and the magnet 25 are the same as those of the electromagnetic electroacoustic transducer 1100 of the second embodiment shown in FIG.

As shown in a plan view in FIG. 7, the electromagnetic electroacoustic transducer 1200 includes a suspension 21 integrally formed with the magnetic body 12 ′, a cylindrical housing 27 that supports the suspension 21 around its periphery, and a cover. 20 'and a diaphragm 29 integrally formed therewith. The outer peripheral portion of the diaphragm 29 and the outer peripheral portion of the suspension 21 coincide and are located on the same plane.

As in the first embodiment, the diaphragm 29 is made of a resin material PEN, and the suspension 21 integrally formed with the magnetic body 12 'is made of permalloy.

The electromagnetic electro-acoustic transducer 120 as described above
For 0, its operation will be described.

In the initial state where no current flows through the coil 4,
Magnet 25, magnetic thin plate 15, suspension 2
The point that a magnetic path is formed by the center pole 13, the center pole 13, and the yoke 6 is the same as in the second embodiment. The vibration operation is the same as in the second embodiment.

The electromagnetic electro-acoustic transducer 1200 differs from the electromagnetic electro-acoustic transducer 1100 of the second embodiment in that the suspension 21 is formed integrally with the magnetic body 12 ′, and the diaphragm 29 is formed of a cover 20 ′. By integrally molding each, the number of parts and the number of steps are reduced, so that the cost can be reduced. In addition, since the variations during assembly are eliminated by integrally molding, variations in characteristics as a product can be reduced. Further, as shown in FIG. 7, the suspension 21 and the magnetic body 12 'may be integrally formed as a flat plate.

In the electromagnetic electroacoustic transducer 1200, the suspension 21 and the outer peripheral portion of the diaphragm 29 coincide with each other and are located on the same plane, so that the positioning of the suspension 21 and the diaphragm 29 is facilitated, and the assembling is facilitated. Since there is no variation in time, variation in characteristics as a product can be reduced.

(Embodiment 4) As Embodiment 4 of the present invention, a portable telephone 61 which is a portable terminal equipped with the electromagnetic electro-acoustic transducer of the present invention will be described with reference to FIGS. 8A and 8B. .

FIG. 8A is a partially cutaway perspective view of portable telephone 61 according to Embodiment 4 of the present invention. FIG. 8B shows a block diagram of the inside 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 the first, second and third embodiments of the present invention is used.
0, 1100 or 1200 applies. The electromagnetic electro-acoustic transducer 64 is provided inside the housing 62 such that the diaphragm faces the sound hole 63.

As shown in FIG. 8B, 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, for example, a semiconductor memory. 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 with the conventional portable telephone, the portable telephone 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 such a portable terminal device 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. When the ringing signal is input to the electromagnetic electroacoustic transducer 64, the electromagnetic electroacoustic transducer 64 outputs a ringtone 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 electro-acoustic 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 answering machine in the state where the power is on, the contents of the transmission are stored in the answering machine 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 sound enhancement level and output to the electromagnetic electroacoustic transducer 64.
At this time, the electromagnetic electroacoustic transducer 64 operates as a receiver or a speaker and outputs a message.

An electromagnetic electro-acoustic transducer built in a portable terminal typified by a conventional portable telephone has a high minimum resonance frequency and has been used only for ringing tone reproduction.

However, the electromagnetic type electro-acoustic transducer of the present invention can lower the lowest resonance frequency. Therefore, if the electromagnetic type electro-acoustic transducer of the present invention is used for a portable terminal, it is possible to reproduce a voice signal and to call out. Both sound 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 mobile phone 61, the electromagnetic electroacoustic transducer 64 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 increase the sound pressure of the ringing tone.

Although the electromagnetic electro-acoustic transducer 64 is provided so that the diaphragm faces the sound hole, it may be provided so that the yoke side faces the sound hole.

FIGS. 8A and 8B show a portable telephone as an example of a portable terminal. However, the present invention is not limited to this, and an electromagnetic electroacoustic transducer such as a pager, a notebook computer, a PDA, and a wristwatch is mounted. The present invention is applied to a portable terminal that is used.

[0085]

The electromagnetic electro-acoustic transducer of the present invention includes a magnetic body, a suspension for fixing and supporting the magnetic body at the center, and a diaphragm connected to the suspension. Unlike the related art, since the magnetic body is supported by the suspension, the diaphragm need not support the magnetic body. Therefore,
The shape of the diaphragm can be freely designed so as to obtain good acoustic characteristics. Furthermore, in addition to being able to reproduce low-frequency frequencies such as sound by reducing the elastic constant of the diaphragm, the distortion of the diaphragm is reduced, and the flatness of the amplitude characteristics with respect to the input voltage of the diaphragm is improved. Can be improved.

Further, according to the electromagnetic electro-acoustic transducer of the present invention, since a metal material such as stainless steel is used as a material of the suspension for supporting the magnetic material, a durable electromagnetic electro-acoustic transducer having almost no change with time is used. An acoustic transducer can be realized. Thus, an electromagnetic electroacoustic transducer that satisfies both acoustic characteristics and reliability is provided by the suspension supporting the magnetic material.

According to the electromagnetic electro-acoustic transducer of the present invention, since the magnetic thin plate is provided between the magnet and the diaphragm, the magnetic flux can be efficiently guided into the magnetic body. The driving force increases and the sound pressure can be increased.

Further, according to the electromagnetic electro-acoustic transducer of the present invention, a hole is formed in the center of the magnetic body and the suspension, and the center pole is disposed so as to penetrate the hole, so that the magnetic path is formed. The distance between the magnetic body to be formed and the center pole can be reduced. As a result, it is possible to obtain a driving force sufficient to cause the diaphragm to have a large amplitude, and to reproduce a high sound pressure.

Further, according to the portable terminal device of the present invention, by mounting the electromagnetic electro-acoustic transducer of the present invention, reproduction of alarm sound, melody sound and voice can be realized by one electromagnetic electro-acoustic transducer. be able to. As a result, it is possible to reduce the number of sound transducers that are built in a plurality of portable terminals.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electromagnetic electro-acoustic transducer according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a magnetic body according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a suspension according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an electromagnetic electro-acoustic transducer according to Embodiment 2 of the present invention.

FIG. 5 is a diagram showing a magnetic body, a suspension, and a diaphragm according to a second embodiment of the present invention.

FIG. 6 shows an electromagnetic electro-acoustic transducer according to Embodiment 3 of the present invention.

FIG. 7 is a diagram showing a suspension according to a third embodiment of the present invention.

FIG. 8A is a diagram showing a portable terminal device according to Embodiment 4 of the present invention.

FIG. 8B is a block diagram showing the inside of the portable terminal according to Embodiment 4 of the present invention;

FIG. 9 is a diagram showing a conventional electromagnetic electro-acoustic transducer.

FIG. 10 shows a force of a diaphragm of a conventional electromagnetic electro-acoustic transducer.
Diagram showing static attraction generated on diaphragm by displacement curve and magnet

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11, 21 Suspension 2, 12 Magnetic body 3, 13 Center pole 4 Coil 5 Magnet 6 Yoke 7, 27 Housing 9, 19, 29 Vibration plate 10 Spacer 15 Magnetic thin plate 20 Cover

Claims (14)

[Claims] 1. A magnetic body, a suspension for fixing and supporting the magnetic body at the center, a diaphragm connected to the suspension, a magnet for generating a DC magnetic flux in the magnetic body, An electromagnetic electro-acoustic transducer comprising: a coil for generating an AC magnetic flux. 2. The electromagnetic electro-acoustic transducer according to claim 1, wherein the suspension has a stiffness value in a vibration direction larger than that of the diaphragm. 3. The magnet is disposed so as to surround the coil, and includes a center pole provided on an inner peripheral side of the coil, and a yoke provided on a side opposite to the diaphragm with respect to the coil. The electromagnetic electro-acoustic transducer according to claim 1, further comprising: 4. The electromagnetic electro-acoustic transducer according to claim 1, wherein said diaphragm is made of resin. 5. The electromagnetic electro-acoustic transducer according to claim 1, wherein said suspension is made of metal. 6. The suspension is non-magnetic,
The electromagnetic electro-acoustic transducer according to claim 1. 7. The electromagnetic electroacoustic transducer according to claim 1, further comprising a magnetic thin plate provided between the magnet and the diaphragm. 8. The electromagnetic electro-acoustic transducer according to claim 1, wherein a hole is formed in a central portion of the magnetic body. 9. The electromagnetic electro-acoustic transducer according to claim 8, further comprising a cover that covers the hole. 10. A magnetic body, a suspension for fixing and supporting the magnetic body at the center, a diaphragm connected to the suspension, a yoke provided facing the diaphragm, and a yoke for the yoke. A center pole provided on the diaphragm side; a coil arranged to surround the center pole; and a magnet arranged to surround the coil. The magnetic body and the suspension each have a hole. An electromagnetic electro-acoustic transducer formed, wherein the center pole has a shape that can be inserted into the hole, and the height of the upper surface of the center pole is equal to or higher than the lower surface of the magnetic body. 11. The electromagnetic electroacoustic transducer according to claim 1, wherein the suspension and the magnetic body are integrated. 12. The electromagnetic electro-acoustic transducer according to claim 1, wherein an outer peripheral portion of the diaphragm and an outer peripheral portion of the suspension are on the same plane. 13. A portable terminal device comprising the electromagnetic electro-acoustic transducer according to claim 1. 14. A portable terminal device comprising the electromagnetic electro-acoustic transducer according to claim 10.