JPH10285689A - Acoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact electromagnetic coupling type acoustic transducer having high sensitivity, large input, large output and a full band type or bass only at a low cost. SOLUTION: A magnetic body 14A is attached to the center pat front surface of a yoke 14, a magnet 20 is attached to the front surface of the magnetic body 14A, a pole piece 15 is attached to the front surface of the magnet 20, a plate 30 is attached to the peripheral part front surface of the yoke 14 and a gap 5 is formed between the outer peripheral surface of the pole piece 15 and the inner peripheral surface of the plate 30. A flatly wound driving coil 1 is arranged between the peripheral part of the yoke 14 and the plate 30. The driving coil 1 is annularly wound on an inner peripheral side as a winding start and an outer peripheral side as a winding end and the inner periphery of the driving coil 1 is roughly positioned on the inner peripheral surface of the plate 30 in a gap long direction. Into the gap 5, a shorted secondary coil 7 fixed to a diaphragm 50 is inserted. The length of the gap 5 is turned to the one for which a clearance is added to the thickness of the secondary coil 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic transducer of the electromagnetic coupling type (electromagnetic induction type), that is, an electroacoustic transducer for converting an electric signal into sound such as a speaker or a headphone, and a microphone or the like. More specifically, the present invention relates to an acousto-electric converter for converting sound into an electric signal.

[0002]

2. Description of the Related Art In the case of an electromagnetic coupling type acoustic transducer, for example, in the case of an external magnet type, a magnet is sandwiched between a plate and a center pole yoke, and a plate and a center pole portion of the center pole yoke are connected. A magnetic circuit having a gap between them is formed, and a first coil is fixed to a plate or a center pole portion in the gap of the magnetic circuit, and is fixed to a diaphragm so as to face the first coil. , And the shorted second coil is arranged.

In an electroacoustic transducer such as a speaker or a headphone, when a first coil is used as a driving coil (primary coil) and a signal current is supplied to the driving coil (primary coil), the signal is supplied to a second coil serving as a secondary coil by electromagnetic coupling. A corresponding secondary current is induced, and a driving force corresponding to the signal current is generated in the second coil according to Fleming's left-hand rule, and the diaphragm to which the second coil is fixed vibrates to respond to the signal current. Sound pressure is generated.

In an acoustoelectric converter such as a microphone,
When the diaphragm vibrates due to the sound pressure, a primary current according to the sound pressure is induced in the second coil serving as a primary coil fixed to the diaphragm, and the first coil serving as an output coil (secondary coil) Then, an output current corresponding to the sound pressure is generated.

FIGS. 11 and 12 show examples of conventional electromagnetically coupled speakers, respectively. FIG. 11 shows a case where a drive coil is attached to a plate, and FIG. 12 shows a case where a drive coil is attached to a center pole portion.

That is, in the electromagnetically coupled speaker of FIG. 11, a magnet 20 is attached to the front surface of the bottom of the center pole yoke 10 and the plate 3
The magnetic circuit 6 having the gap 5 between the outer peripheral surface of the tip of the center pole portion 11 of the center pole yoke 10 and the inner peripheral surface of the plate 30 is formed. Attach the drive coil 1.

A hole 1 is formed at the bottom of the center pole yoke 10.
2, the terminal plate 4 having the input terminal 3 attached to the rear surface is attached, and the lead 2 of the drive coil 1 is inserted into the hole 12 and connected to the input terminal 3 by soldering. Leader 2
Are provided at the beginning and end of winding of the drive coil 1, respectively, and each is connected to a separate input terminal.

A secondary coil 7 is inserted into the gap 5. The secondary coil 7 is a one-turn short-circuited cylinder made of a nonmagnetic conductive material, for example, aluminum.
Alternatively, the winding is wound over a plurality of turns to be a short-circuited winding.

The bottom of the frame 40 is attached to the front surface of the plate 30, and the outer edge 51 and the gasket 45 of the diaphragm 50 such as cone paper are attached to the outer periphery of the frame 40. Further, the outer peripheral portion of the damper 47 is attached to the frame 40, and the inner peripheral portion of the diaphragm 50 and the damper 4 are mounted.
7 is attached to the secondary coil 7, and the center cap 49 is attached to the inner periphery of the diaphragm 50 or the tip of the secondary coil 7.

In the electromagnetically coupled speaker of FIG. 12, a concave portion is formed on the outer peripheral surface of the tip of the center pole portion 11 of the center pole yoke 10, and the driving coil 1 is attached to the center pole portion 11 by fitting into the concave portion. Others
This is the same as the electromagnetically coupled speaker of FIG.

In the electromagnetically coupled speaker of FIG. 11 or FIG. 12, when a signal current is supplied to the drive coil 1, a secondary current corresponding to the signal current is induced in the secondary coil 7 by the electromagnetic coupling, so that the left hand of Fleming can be used. A driving force corresponding to the signal current is generated in the secondary coil 7 according to the law of
The diaphragm 50 to which is fixed vibrates, and a sound pressure corresponding to the signal current is generated.

[0012]

However, FIG.
Alternatively, in the conventional electromagnetically coupled speaker shown in FIG. 12 and described above, since the drive coil 1 is disposed in the gap 5 of the magnetic circuit 6, the length of the gap 5 (the center of the speaker (The length in the vertical direction) cannot be reduced, the magnetic force in the gap 5 becomes weak, and the sensitivity of the speaker decreases. To increase the magnetic force in the gap 5 and increase the sensitivity of the speaker, the magnet 20
When a large speaker is used, the size of the speaker increases and the cost of the speaker increases.

In addition, if the number of turns of the drive coil 1 is increased in order to increase the inductance of the drive coil 1, the length of the gap 5 is correspondingly increased and the sensitivity of the speaker is reduced, so that the inductance of the drive coil 1 is increased. Can not do it. Therefore, the driving coil 1
The electromagnetic coupling force between the coil and the secondary coil 7 is reduced in a low frequency range of about 2 kHz or less, so that low-frequency sound cannot be reproduced. for that reason,
Conventional electromagnetically coupled speakers can only be used for high-frequency sound reproduction.

The outer peripheral surface or the inner peripheral surface of the drive coil 1 is in contact with the plate 30 or the center pole portion 11, but the contact area is small, and the inner peripheral surface or the outer peripheral surface of the drive coil 1 has a gap 5. The drive coil 1 is opposed to the center pole 11 or the plate 30.
Heat is not dissipated instantaneously. Therefore, coupled with the fact that a thick wire cannot be used as the drive coil 1, a large current cannot be suddenly applied to the drive coil 1 and the allowable input signal level of the speaker cannot be increased.

The above is the case of a speaker, but the same applies to other electroacoustic transducers such as headphones. The same applies to an acoustoelectric converter such as a microphone, except that the input and output are reversed.

That is, the conventional electromagnetic coupling type acousto-electric transducer has low sensitivity as a transducer, and if a large magnet is used to increase the sensitivity, the size of the transducer increases, and the size of the transducer increases. Causes cost increase.
In addition, the electromagnetic coupling force between the primary coil (second coil) and the output coil (secondary coil, first coil) is low in a low frequency range, so that it is not possible to obtain low-pitched sound, and from the viewpoint of heat radiation of the output coil, The allowable input sound pressure level of the transducer cannot be increased.

Therefore, the present invention provides an electromagnetic coupling type acoustic transducer, in which, first, the sensitivity as a transducer can be increased without increasing the size and cost of the transducer. In addition, it is possible to reproduce or collect bass, thereby realizing a full-band converter or a converter dedicated to bass. Third, the allowable input of the converter is reduced in terms of heat radiation of the first coil. The level can be increased.

[0018]

According to the present invention, a first magnetic component and a second magnetic component of a first magnetic component, a second magnetic component and a third magnetic component forming a magnetic circuit together with a magnet. A gap is formed between the opposing peripheral surfaces of the body part, and a gap is formed between a portion of the third magnetic part located on the rear side of the acoustic transducer with respect to the first magnetic part and the first magnetic part. , A flat coiled first coil is arranged,
A short-circuited second coil fixed to the diaphragm is arranged in the gap.

Here, “flat” means that the thickness is sufficiently smaller than the outer diameter.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an electro-acoustic transducer such as a speaker or a headphone, a first magnetic member among a first magnetic member, a second magnetic member and a third magnetic member constituting a magnetic circuit together with a magnet. A gap is formed between opposing peripheral surfaces of the component and the second magnetic component, and a portion of the third magnetic component located on the rear side of the electroacoustic transducer with respect to the first magnetic component and the first magnetic component. A flatly wound drive coil (primary coil) is arranged between the body parts, and a short-circuited secondary coil fixed to the diaphragm is arranged in the gap.

In the case of the inner magnet type, the first magnetic component is a plate, the second magnetic component is a pole piece, and the third magnetic component is a yoke. The circumference is located substantially on the inner peripheral surface of the first magnetic component.

That is, a flatly wound drive coil is mounted on the front surface of the yoke peripheral portion, a plate is mounted on the front surface of the drive coil, a magnet is mounted on the front surface of the yoke central portion, and a pole piece is mounted on the front surface of the magnet. A gap is formed between the inner peripheral surface of the plate and the outer peripheral surface of the pole piece, and the inner periphery of the drive coil is located substantially on the inner peripheral surface of the plate.

In the case of the external magnet type, the first magnetic component is a pole piece, the second magnetic component is a plate, the third magnetic component is a yoke, and the outer periphery of a flatly wound drive coil is used. Is located substantially on the outer peripheral surface of the first magnetic component.

That is, a flatly wound drive coil is mounted on the front surface of the yoke center, a pole piece is mounted on the front surface of the drive coil, a magnet is mounted on the front surface of the yoke peripheral portion, and a plate is mounted on the front surface of the magnet. A gap is formed between the outer peripheral surface of the pole piece and the inner peripheral surface of the plate, and the outer periphery of the drive coil is located substantially on the outer peripheral surface of the pole piece.

One drive coil disposed between the yoke and the plate or between the yoke and the pole piece is wound in one layer (one turn) or a plurality of layers (multiple turns) in the axial direction of the transducer. It can be turned. Also, 1
One drive coil can be composed of a plurality of coils that are divided and wound in the gap length direction, and in that case, the plurality of coils can be connected in series or in parallel.

It is also possible to arrange two or more flatly wound drive coils one above the other between the yoke and the plate or between the yoke and the pole piece. The coils can be connected in series or in parallel.

The two or more drive coils are each composed of a plurality of coils which are divided and wound in the gap length direction, and the plurality of coils are all connected in series or in parallel in the two or more drive coils. Or connected in parallel in one drive coil and connected in series in two or more drive coils, or two or more drives connected in series in one drive coil It can be connected in parallel in the coil.

However, in the case where two or more drive coils each wound flat are provided, it is better to arrange a magnetic body between two drive coils adjacent in the axial direction of the converter. It is desirable from the viewpoint of heat radiation of the coil.

In the electroacoustic transducer according to the present invention, the drive coil does not exist in the gap between the inner peripheral surface of the plate and the outer peripheral surface of the pole piece. Therefore, the gap length of the magnetic circuit can be obtained by adding the clearance to the thickness of the secondary coil, and the gap length can be reduced regardless of the wire diameter and the number of turns of the drive coil. Therefore, the magnetic force in the gap can be increased without using a large magnet, and the sensitivity of the electroacoustic transducer can be increased.

Further, even if the number of turns of the drive coil is increased in order to increase the inductance of the drive coil, the gap length is not increased and the sensitivity of the electroacoustic transducer is not reduced, so that the inductance of the drive coil is increased. be able to. Therefore, the electromagnetic coupling force between the drive coil and the secondary coil can be increased even in a low frequency range, and low-frequency sound can be reproduced. Therefore, it is possible to realize an all-band type or low-tone dedicated converter.

Further, since the drive coil contacts the plate and the yoke or the pole piece and the yoke on a wide surface facing the front side and the rear side of the converter, the heat from the drive coil is instantaneously released. Therefore, coupled with the fact that a thick wire can be used as the drive coil, a large current can be suddenly applied to the drive coil, and the allowable input signal level of the converter can be increased.

In an electroacoustic transducer such as a speaker or a headphone, a driving coil can be driven by a digital audio signal, as described later.

In an acoustoelectric converter such as a microphone,
The flat wound coil is referred to as an output coil (secondary coil), and the short-circuited coil fixed to the diaphragm is referred to as a primary coil. The first magnetic component, the second magnetic component, and the third magnetic component are the same as in the case of the electroacoustic transducer.

Also, in the case of an acousto-electric transducer, as in the case of the electro-acoustic transducer, one output coil can be constituted by a plurality of coils divided and wound in the gap length direction. At the same time, two or more output coils each wound flat can be provided.

According to the acousto-electric transducer of the present invention, firstly, for the same reason as described above for the electro-acoustic transducer, the sensitivity of the acousto-electric transducer can be increased without using a large magnet. Can be higher,
Secondly, the bass can be collected, and an acousto-electric transducer dedicated to the full band or the bass can be realized.
In addition, the allowable input sound pressure level of the converter can be increased in terms of heat radiation of the output coil.

The diaphragm of the acoustic transducer according to the present invention has a flat shape in the case of a speaker, and has a dome portion and an edge portion in the case of a headphone or a microphone. The shape can be appropriately selected.

Hereinafter, several embodiments of the present invention will be described. However, these embodiments are merely examples of the present invention, and the present invention is not limited to these embodiments.

[0038]

【Example】

[Embodiment 1] FIG. 1 shows a first embodiment of an acoustic transducer according to the present invention, in which a driving coil is provided between a peripheral portion of a yoke and a plate in an internal magnet type electromagnetically coupled speaker.

In this example, the magnetic body 14A is mounted on the front surface of the central portion of the yoke 14 whose peripheral portion protrudes forward, the magnet 20 is mounted on the front surface of the magnetic material 14A, and the pole piece 15 is mounted on the front surface of the magnet 20. The plate 30 is attached to the front surface of the yoke 14 to form a magnetic circuit 6 having a gap 5 between the outer peripheral surface of the pole piece 15 and the inner peripheral surface of the plate 30. One drive coil (primary coil) 1 wound flat is disposed between the peripheral portion and the plate 30.

The secondary coil 7 is inserted into the gap 5. The secondary coil 7 is a one-turn short-circuited cylinder made of a nonmagnetic conductive material, for example, aluminum.
Alternatively, the winding is wound over a plurality of turns to be a short-circuited winding.

The bottom of the frame 40 is attached to the front surface of the plate 30, and the outer edge 51 and the gasket 45 of the diaphragm 50 such as cone paper are attached to the outer periphery of the frame 40. Further, the outer peripheral portion of the damper 47 is attached to the frame 40, and the inner peripheral portion of the diaphragm 50 and the damper 4 are mounted.
7 is attached to the secondary coil 7, and the center cap 49 is attached to the inner periphery of the diaphragm 50 or the tip of the secondary coil 7.

As shown in FIG. 5, the drive coil 1 is wound in an annular shape with the inner periphery being the start of winding and the outer periphery being the end of winding, and the lead wires 1s and 1e being formed at the beginning and end of the winding.
Is provided.

Further, as shown in FIG.
Can be composed of, for example, three coils 1P, 1Q, and 1R that are divided and wound in the gap length direction. In this case, each of the coils 1P, 1Q, and 1R is provided with lead wires 1s and 1e at the beginning and end of winding, with the winding on the inner circumference side and the winding end on the outer circumference side.

In this case, each of the coils 1P, 1Q,
By connecting the 1R in parallel, a larger input current can be passed through the drive coil 1 using a thin wire, and the resistance on the primary side of the speaker is reduced, so that the matching with the amplifier that drives the speaker can be achieved. Becomes easier.

At this time, the number of turns of the coils 1P, 1Q, 1R may be substantially the same, but the resistances of the coils 1P, 1Q, 1R are the same, and the same current flows through the coils 1P, 1Q, 1R. In addition, the coil 1Q intermediate from the inner coil 1P is the coil 1Q outside the intermediate coil 1Q.
For R, it is desirable to use a thicker wire.

In the periphery of the yoke 14, an annular shallow groove is formed on the front surface, and the hole 12 is formed.
A terminal plate 4 to which the input terminal 3 is attached is attached to the back surface of the drive coil 1, and the drive coil 1 that is not divided as shown in FIG. 5 or divided as shown in FIG. The lead wires 1s and 1e of the drive coil 1 are passed through the holes 12 of the yoke 14 and connected to the input terminals 3 by soldering. The leads 1s and 1e are connected to separate input terminals.

In the gap length direction, the inner circumference of the drive coil 1 is located on the inner circumference of the plate 30. As a result, the magnetic force in the gap 5 is sufficiently utilized, and as described later, the sensitivity of the speaker is sufficiently increased, and the electromagnetic coupling force between the drive coil 1 and the secondary coil 7 is low. But it gets big enough.

As the magnet 20, a neodymium magnet, a samarium-cobalt magnet, or the like can be used. When these magnets are used,
The magnet 20 can have a sufficiently strong magnetic force and a minimum thickness of approximately 1 mm. The outer diameters of the magnet 20 and the pole piece 15 are equal to each other. The outer diameter of the magnetic body 14A is equal to or slightly smaller than the outer diameters of the magnet 20 and the pole piece 15.

In the above-described electromagnetically coupled speaker, when a signal current is supplied to the drive coil 1, a secondary current corresponding to the signal current is induced in the secondary coil 7 by the electromagnetic coupling, and the secondary current is obtained by Fleming's left-hand rule. A driving force corresponding to the signal current is generated in the coil 7, and the diaphragm 5 to which the secondary coil 7 is fixed
0 vibrates, and a sound pressure corresponding to the signal current is generated.

According to this example, the driving coil 1
Does not exist in the gap 5 between the inner peripheral surface of the plate 30 and the outer peripheral surface of the pole piece 15. Therefore, the length of the gap 5 can be obtained by adding the clearance to the thickness of the secondary coil 7, and the length of the gap 5 can be reduced regardless of the wire diameter and the number of turns of the drive coil 1. Accordingly, the magnetic force in the gap 5 can be increased without using a large magnet 20 as a magnet, that is, without increasing the size and cost of the speaker, and the sensitivity of the speaker can be increased.

In practice, the thickness of the secondary coil 7 is set to 0.15 m.
m, the length of the gap 5 is 0.40
It can be significantly reduced, for example, to about 0.55 mm when mm is added.

Further, even if the number of turns of the drive coil 1 is increased to increase the inductance of the drive coil 1, the length of the gap 5 does not increase and the sensitivity of the speaker does not decrease. Can be increased. Therefore, the electromagnetic coupling force between the drive coil 1 and the secondary coil 7 can be increased even in a low frequency range, and low-frequency sound can be reproduced. Therefore, it is possible to realize an all-band type or a speaker dedicated to bass.

In order to make the electromagnetically coupled speaker of the embodiment a speaker dedicated to low-pitched sound, the secondary coil 7 is made slightly thicker to make the secondary coil 7 heavier, the speaker support system is made to be high compliance, and the minimum of the speaker vibration system is set. It is desirable to lower the resonance frequency. Even if the secondary coil 7 is a one-turn short-circuited cylinder made of copper that is heavier than aluminum, or a wire such as a copper wire wound over a plurality of turns and short-circuited, the mass of the speaker vibration system is increased. And the lowest resonance frequency can be lowered.

Further, according to the electromagnetically coupled speaker of the embodiment, since the drive coil 1 contacts the plate 30 and the yoke 14 on a wide surface facing the front and rear sides of the speaker, the heat radiation from the drive coil 1 is instantaneously released. Done.
Therefore, in combination with the fact that a thick wire having a diameter of, for example, 0.25 mm can be used as the drive coil 1, a large current can be suddenly applied to the drive coil 1 and the allowable input signal level of the speaker can be increased.

In summary, according to the electromagnetically coupled speaker of the embodiment, it is possible to realize a small-sized, low-cost, high-sensitivity, large-input / large-output, all-band or low-frequency speaker.

The electromagnetically coupled speaker of FIG. 1 can be assembled by the following method. First, yoke 1
The terminal plate 4 to which the input terminal 3 is attached is attached to the back surface of the drive coil 4, and the drive coil 1 is wound as described above to form a yoke 14.
The lead wires 1 s and 1 e are passed through the holes 12 of the yoke 14 and connected to the input terminals 3.

Next, an adhesive is applied to the front surface of the central portion of the yoke 14 to mount the magnetic body 14A. At this time, the yoke 14
And the center of the magnetic body 14A are concentric.

Next, an adhesive is applied to the front surface of the magnetic body 14A, and a magnet (precisely, before magnetizing) 20 is mounted thereon.
A gap guide (not shown) is inserted into the magnet 20 so that the outer diameter of the magnet 20 is concentric with the inner diameter of the yoke 14.

Further, an adhesive is applied to the front surface of the magnet 20 and the pole piece 15 is placed thereon, and the adhesive is applied to the front surface of the yoke 14 to which the drive coil 1 is fixed as described above, and the plate 30 is placed thereon. . At this time, the outer diameter of the pole piece 15 is made concentric with the inner diameter of the yoke 14 by the gap guide, and the inner diameter of the plate 30 is reduced by the magnet 20 and the pole piece 15.
Concentric with the outside diameter of

After the adhesive is dried, the gap guide is removed from the magnet 20 and the pole piece 15. At this stage, a gap 5 having a predetermined length is formed between the outer peripheral surface of the pole piece 15 and the inner peripheral surface of the plate 30.

Next, the frame 40 is attached to the plate 30 by means such as screws. Alternatively, the frame 40 may be attached to the plate 30 in advance by means such as screws.

Next, a coil spacer (not shown) is inserted into the inner diameter of the secondary coil 7, and the coil spacer is inserted into the pole piece 15 and the magnet 20 so that the secondary coil 7 is located at a predetermined position in the gap 5. .

Next, the outer periphery of the damper 47 is
0, the inner peripheral portion is adhered to the secondary coil 7, and the outer edge 51 of the diaphragm 50 and the gasket 45 are adhered to the frame 40, and the inner peripheral portion of the diaphragm 50 is attached to the secondary coil 7. Glue.

Next, after the adhesive is dried, the coil spacer is removed from the pole piece 15 and the magnet 20, and the center cap 49 is adhered to the inner peripheral portion of the diaphragm 50 or the tip of the secondary coil 7. After the adhesive is dried, the magnet 20 is magnetized to complete the speaker assembly.

FIG. 1 shows an example in which the terminal plate 4 on which the input terminal 3 is mounted is mounted on the back surface of the yoke 14. A slit is formed at a predetermined angular position of the plate 30, and the input is formed on the outer peripheral surface of the plate 30. Attach the terminal plate to which the terminals are attached, and lead wires 1s and 1e of the drive coil 1.
May be drawn out from the slit of the plate 30 to the outer peripheral side of the plate 30 and connected to the input terminal.

Further, a slit is formed at a predetermined angular position of the plate 30, and a terminal plate having an input terminal is mounted on the frame 40, and the lead wire 1 s
And 1e are moved from the slit of the plate 30 to the frame 4
0 may be pulled out, fixed to the frame 40 with an adhesive, and connected to the input terminal.

Further, the plate 30 and the frame 40
A slit is formed at the same angular position on the bottom of the
A terminal plate having an input terminal attached thereto is attached to the frame 40, and the lead wires 1s and 1e of the drive coil 1 are drawn out of the slit of the plate 30 and the slit at the bottom of the frame 40 to the inside of the frame 40, and fixed to the frame 40 with an adhesive. Then, it may be connected to the input terminal.

[Embodiment 2] FIG. 2 shows a second embodiment of the acoustic transducer according to the present invention, which is an internal magnet type electromagnetically coupled speaker similar to Embodiment 1 of FIG. This is a case where a drive coil is provided in between.

In this example, between the plate 30 and the peripheral portion of the yoke 14, each of the annular magnetic members 1 having a small thickness is provided.
4B and 14C, the plate 30 and the magnetic body 1
The drive coils 1S, 1T, and 1U, which are wound flat, are arranged between the magnetic material 14B and the magnetic material 14B and the magnetic material 14C, and between the magnetic material 14C and the peripheral portion of the yoke 14, respectively.

As shown in FIG. 5, the drive coils 1S, 1
Each of T and 1U is wound in an annular shape with the inner circumferential side being the start of winding and the outer circumferential side being the end, and lead lines 1s and 1e are provided at the start and end of each winding.

Then, for example, the magnetic members 14B and 14B
A slit is formed at a predetermined angular position in C, a hole is formed in the outer peripheral portion of the yoke 14 so as to communicate with the slits of the magnetic bodies 14B and 14C, and a hole 12 is also formed in the bottom of the yoke 14. A terminal plate 4 to which the input terminal 3 is attached is attached to the drive coil 1S, and the lead wires 1s and 1e of the drive coil 1S pass through the slit of the magnetic body 14B and the hole on the outer peripheral portion of the yoke 14, and are drawn out of the drive coil 1T. Are connected to the input terminal 3 through the slit of the magnetic body 14C and the hole at the outer peripheral portion of the yoke 14, and the lead wires 1s and 1e of the drive coil 1U are passed through the hole 12 at the bottom of the yoke 14.

In the gap length direction, the driving coil 1
The inner circumferences of S, 1T and 1U are located on the inner circumference of the plate 30, respectively. Also in this example, as the magnet 20, neodymium magnet or samarium cobalt
A magnet or the like can be used. However, in this example, the bottom of the yoke 14 is made flat, the thickness of the magnet 20 is made relatively large, and the magnet 20 is directly attached to the front surface of the center of the yoke 14. The outer diameter of the magnet 20 is equal to the outer diameter of the pole piece 15,
Slightly smaller. Others are the same as the first embodiment.

In this case, the drive coils 1S, 1T and 1
U can be connected in series, in which case the number of turns of one drive coil can be increased as a whole, and the inductance can be increased.

The driving coils 1S, 1T and 1U can be connected in parallel. In that case, a larger input current can flow through one drive coil as a whole, and the resistance on the primary side of the speaker is reduced, thereby facilitating matching with the amplifier that drives the speaker.

Further, as shown in FIG. 7, each of the drive coils 1S, 1T, 1U is connected to five coils 1E-1A, 1J-1 having the same number of turns in the gap length direction.
F, 10 to 1K. Again,
Each coil 1E-1A, 1J-1F, 10-1K
, With the inner circumference side as the winding start and the outer circumference side as the winding end,
Lead wires 1s and 1e are provided at the beginning and end of the winding.

As shown in FIG. 8, each drive coil 1S, 1T, 1U is arranged such that the ratio of the number of turns in the gap length direction is N: N / 2: N / 4: N / 8: N / 16. It can also be divided into five coils 1E to 1A, 1J to 1F, and 10 to 1K. Again, each coil 1
In E to 1A, 1J to 1F, and 10 to 1K, the lead wires 1s and 1e are provided at the beginning and end of the winding with the inner periphery being the beginning and the outer periphery being the end.

When the drive coil is divided into a total of fifteen coils 1A to 10 as shown in FIG. 7 or FIG.
It can be driven by a bit digital audio signal.

[Embodiment 3] FIG. 3 shows a third embodiment of an acoustic transducer according to the present invention, which is an externally magnetized electromagnetically coupled speaker, which is provided between a center pole portion of a center pole yoke and a pole piece. This is a case where a drive coil is provided.

In this example, the center pole yoke 10
An annular shallow groove is formed on the front surface of the center pole portion 11, the flatly wound drive coil 1 is mounted in the groove, the pole piece 15 is mounted on the front surface of the drive coil 1, and the center pole yoke 10 The magnet 20 is attached to the front surface of the peripheral portion, and the plate 30 is attached to the front surface of the magnet 20 to form the gap 5 between the outer peripheral surface of the pole piece 15 and the inner peripheral surface of the plate 30.

Center pole part 11, pole piece 15
And the outer diameters of the drive coils 1 are made equal to each other. Therefore, the outer periphery of the drive coil 1 is located on the outer peripheral surface of the pole piece 15 in the gap length direction.

In this case, for example, a hole 12 is formed in the bottom of the center pole yoke 10 and a terminal plate 4 on which an input terminal 3 is mounted is mounted on the back surface.
Are fixed to the outer peripheral surface of the center pole portion 11 with an adhesive, and are connected to the input terminal 3 through the holes 12. Others are the same as the first embodiment in FIG.

According to the third embodiment, similarly to the first embodiment, a small-sized, low-cost, high-sensitivity, large-input, large-output speaker dedicated to all bands or a low tone can be realized.

[Embodiment 4] FIG. 4 shows a fourth embodiment of an acoustic transducer according to the present invention, which is an inner-magnet type electromagnetically coupled microphone, in which an output coil (secondary coil) is provided between the periphery of the yoke and the plate. ) Is provided.

In this example, a magnet 20 having a center hole 20c communicating with the center hole 14c of the yoke 14 is attached to the front surface of the center of the yoke 14 having the center hole 14c.
A pole piece 15 having a center hole 15c communicating with the yoke 14 is attached, an output coil (secondary coil) 8 is attached to a front surface of a peripheral portion of the yoke 14, and a plate 30
And the center hole 14c of the yoke 14 and the magnet 2
0 center hole 20c and the center hole 15 of the pole piece 15.
The sound absorbing material 80 is mounted on the frame 94 forming the cavity 93 at the front inside.

The outer peripheral surface of the pole piece 15 and the plate 30
A gap 5 is formed between the dome portion 5 and the inner peripheral surface of the dome portion 5.
The diaphragm 50 having the primary coil 9 at a position between the diaphragm ring 5 and the diaphragm ring 5
5, the primary coil 9 is inserted into the gap 5, and a cover 96 having a hole 95 is attached to the outer peripheral front surface of the frame 94.

The output coil 8 is wound flat and annularly in the same manner as the drive coil 1 described above, and the primary coil 9 is short-circuited in the same manner as the secondary coil 7 described above.

In this electromagnetically coupled microphone, the cover 9
The diaphragm 50 vibrates due to the sound pressure incident from the hole 95 of the sixth coil 6, so that the primary coil 9 fixed to the diaphragm 50
Thus, a primary current corresponding to the sound pressure is induced, and an output current corresponding to the sound pressure is generated in the output coil 8.

According to the fourth embodiment, it is possible to realize a small-sized, low-cost, high-sensitivity, large-input, large-output microphone dedicated to all bands or bass.

[Embodiment 5] An electroacoustic transducer of the present invention,
For example, an example in which a speaker is driven by a digital audio signal will be described as a fifth embodiment.

FIG. 9 shows an example of a speaker device including a drive unit, for example, 44.1 kHz from a CD player or a DAT (digital audio tape recorder).
Alternatively, the serial data digital audio signal Ds digitized into 16 bits at a sampling frequency of 48 kHz is converted by the serial / parallel converter 110 into a digital audio signal Dp of parallel data.

The 16-bit digital audio signal Dp converted into parallel data is a 2's complement code as shown in FIG. 10 and is linearly quantized. From the digital audio signal Dp, The decoder 120 uses the MSB (most significant bit) of the digital audio signal Dp as a sign bit, and sets four control signals G1 (described later) for each of the lower 15 bits 2SB to LSB (least significant bit) excluding the MSB. To G4.

As shown in FIG. 2, for example, the speaker has three drive coils 1S, 1
T, 1U and each drive coil 1
As shown in FIG. 7, S, 1T, and 1U are divided into five coils 1E to 1E having the same number of turns in the gap length direction.
A, 1J-1F, 10-1K, or as shown in FIG. 8, the ratio of the number of turns is N: N in the gap length direction.
/ 2: N / 4: N / 8: N / 16 5 coils 1
E to 1A, 1J to 1F, and 10 to 1K.

Then, as shown in FIG.
Correspond to the LSB of the digital audio signal Dp, and the coils 1B, 1C ‥‥ 1N, 10 are hereinafter referred to as digital audio signals Dp
In correspondence with 15SB, 14SB @ 3SB and 2SB of the respective coils 1A # 1 as shown in FIG.
For N and 1O, the coil drive circuits 60A ‥‥ 60N,
60O is provided.

The coil drive circuit 60A is configured by, for example, bridge-connecting a constant current source 65A, four FETs 61 to 64 as switching elements, and a corresponding coil 1A, and the FETs 61 and 63 are turned on. FET6
2 and 64 are off, the current Ia of the constant current source 65A is
Flows in the coil 1A in the plus direction, and when the FETs 61 and 63 are off and the FETs 62 and 64 are on, the constant current source 6
5A of current Ia flows in the coil 1A in the negative direction,
When all of the ETs 61 to 64 are on or off, current is prevented from flowing through the coil 1A. The same applies to other coil drive circuits.

The control signals G1 to G4 for the 2SB, 3SB ‥‥ LSB of the digital audio signal Dp from the decoder 120 are transmitted to the FETs 61 to 60N of the corresponding coil drive circuits 60O, 60N ‥‥ 60A.
64 gates.

When the MSB of the digital audio signal Dp is 0 and the corresponding lower-order bit is 1, the control signals G1 and G3 are levels at which the FETs 61 and 63 are turned on, and the control signals G2 and G4 are When the level of the FETs 62 and 64 is turned off and the MSB is 0 and the corresponding lower bit is also 0, or when the MSB is 1 and the corresponding lower bit is 1, the control signals G1 to G4 are
When the MSB is 1 and the corresponding lower-order bit is 0, the control signals G1 and G3 turn off the FETs 61 and 63, and the control signal G2
G4 is a level that turns on the FETs 62 and 64.

Therefore, when the MSB is 0, a signal current flows in the plus direction only when a certain lower bit is 1, and when the MSB is 1, a certain lower bit is 0 when the MSB is 1. , A signal current flows in the negative direction in the corresponding coil.

The driving force F of the vibration system of the electromagnetically coupled electro-acoustic transducer such as an electromagnetically coupled speaker includes a secondary current i induced in the secondary coil, a density B of the magnetic flux generated in the gap of the magnetic circuit, As the product of the length L of the secondary coil in the gap of the magnetic circuit, F = BLi, and the magnetic flux density B and the length L are constant. Is proportional to the secondary current i induced by The secondary current i induced in the secondary coil is proportional to the product of the signal current flowing through the drive coil (primary coil) and the number of turns of the drive coil.

Then, as shown in FIG. 7, the 15 coils 1A
When the number of turns of .about.10 is made equal, the coil drive circuits 60B, 60C, 60D # corresponding to the coils 1B, 1C, 1D # corresponding to the digital audio signal Dp 15SB, 14SB, 13SB # are determined. Current sources 65B, 65
C, 65D}, the current Ib, Ic, Id} is expressed as Ib = 2Ia in relation to the current Ia of the constant current source 65A of the coil drive circuit 60A corresponding to the coil 1A corresponding to the LSB of the digital audio signal Dp. , Ic = 2Ib = 4Ia, Id
= 2Ic = 8Ia ‥‥.

Therefore, in this case, as shown in FIG. 2, the diaphragm 50 to which the secondary coil 7 is fixed is moved in the direction corresponding to the value of the MSB of the digital audio signal Dp to the fifteen coils 1A.
As a result, the audio signal is displaced by an amount proportional to the weight of the bit corresponding to 10, and the audio is reproduced faithfully to the digital audio signal Dp.

Further, as shown in FIG.
The coils 1E, 1J, 1O and the coils 1D, 1I,
1N, coils 1C, 1H, 1M and coils 1B, 1G, 1
The ratio of the number of turns between L and the coils 1A, 1F, 1K is N: N
/ 2: N / 4: N / 8: N / 16, 15SB, 14SB, 13SB, 1 of the digital audio signal Dp
2SB, 11SB, 10SB, 9SB, 8SB, 7S
Coils 1B, 1C, 1D, 1E, 1F, 1G, 1H corresponding to B, 6SB, 5SB, 4SB, 3SB, and 2SB.
Coil drive circuits 60B, 60C, 60D, 60E, 60 corresponding to 1I, 1J, 1K, 1L, 1M, 1N, 1O
F, 60G, 60H, 60I, 60J, 60K, 60
L, 60M, 60N, 60O constant current sources 65B, 65
C, 65D, 65E, 65F, 65G, 65H, 65
I, 65J, 65K, 65L, 65M, 65N, 65O
Currents Ib, Ic, Id, Ie, If, Ig, Ih, I
i, Ij, Ik, Il, Im, In, and Io are expressed as follows: Ia = Ib = Ia = Ib = Ia = Ib = Ia = Ib Ic = Id = Ie, If = Ig =
Ih = Ii = Ij = 32Ia, Ik = Il = Im = In
= Io = 32If = 32 × 32Ia.

Therefore, also in this case, as shown in FIG. 2, the diaphragm 50 to which the secondary coil 7 is fixed is moved in the direction corresponding to the value of the MSB of the digital audio signal Dp. The signal is shifted by an amount proportional to the weight of the corresponding bit, and the sound is reproduced faithfully to the digital sound signal Dp. Moreover, in this case, the ratio of the current value between the minimum current value and the maximum current value is 1:32
The size can be reduced to × 32.

The speaker vibration system hardly reproduces high frequency components exceeding 20 kHz. Therefore, as in each of the above-described examples, each of the coils 1A to
Even if 10 is driven by a digital audio signal Dp having a sampling frequency of 44.1 kHz or 48 kHz, the sampling frequency component is hardly reproduced. Even if the sound is reproduced with a very small sound pressure, the sound exceeding 20 kHz can hardly be heard by the human ear, so that there is no trouble even when listening to music.

According to each of the above-described examples, it is possible to realize a speaker that reproduces sound directly by a digital audio signal without using a D / A converter and a power amplifier, that has a small distortion and a large maximum output. it can.

When the driving coil is driven by the digital audio signal as described above, the driving coil corresponding to the bit having a small driving current is relatively thin, and the driving coil corresponding to the bit having a large driving current is relatively small. By increasing the thickness, it is possible to perform efficient driving with small distortion.

[0106]

As described above, according to the present invention, it is possible to realize a small-sized, low-cost, high-sensitivity, large-input / large-output, full-band or low-tone sound transducer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an acoustic transducer according to a first embodiment.

FIG. 2 is a cross-sectional view illustrating an acoustic transducer according to a second embodiment.

FIG. 3 is a cross-sectional view illustrating an acoustic transducer according to a third embodiment.

FIG. 4 is a sectional view illustrating an acoustic transducer according to a fourth embodiment.

FIG. 5 is a plan view and a cross-sectional view illustrating an example of a first coil.

FIG. 6 is a plan view and a sectional view showing another example of the first coil.

FIG. 7 is a plan view and a cross-sectional view illustrating still another example of the first coil.

FIG. 8 is a plan view and a cross-sectional view illustrating still another example of the first coil.

FIG. 9 is a connection diagram showing an example of a converter device including a drive unit when the electroacoustic converter of the present invention is driven by a digital audio signal.

FIG. 10 is a diagram showing a relationship between each bit of a digital audio signal and each coil in the converter device of FIG. 9;

FIG. 11 is a sectional view showing an example of a conventional electromagnetically coupled speaker.

FIG. 12 is a sectional view showing another example of a conventional electromagnetically coupled speaker.

[Explanation of symbols]

1, 1S, 1T, 1U: drive coil (primary coil), 1
A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1
I, 1J, 1K, 1L, 1M, 1N, 1O, 1P, 1
Q, 1R coil, 1s, 1e lead wire, 3 input terminal, 4 terminal plate, 5 gap, 6 magnetic circuit, 7 secondary coil, 8 output coil (secondary coil), 9 ... Primary coil, 10: Center pole yoke, 11: Center pole part, 14: Yoke, 14A, 14B, 14C: Magnetic body, 15: Pole piece, 20: Magnet, 30 ...
Plate, 40 ... frame, 50 ... diaphragm, 60A-6
00: coil drive circuit, 65A to 65O: constant current source, 1
10 ... Serial / parallel converter, 120 ... Decoder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takahiro Muraguchi, 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Ikuo Shinohara 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (7)

[Claims] 1. A peripheral surface of a first magnetic component and a second magnetic component of a first magnetic component, a second magnetic component, and a third magnetic component constituting a magnetic circuit together with a magnet. A gap is formed between the first magnetic part and the first magnetic part, between the portion of the third magnetic part located on the rear side of the acoustic transducer with respect to the first magnetic part. An acoustic transducer in which one coil is arranged, and a short-circuited second coil fixed to a diaphragm is arranged in the gap. 2. The acoustic transducer according to claim 1, wherein said first coil is a drive coil as a primary coil, and said acoustic transducer is an electroacoustic transducer. 3. The acoustic transducer according to claim 1, wherein said first coil is an output coil as a secondary coil, and said acoustic transducer is an acoustoelectric transducer. 4. The acoustic transducer according to claim 1, wherein the first magnetic component is a plate, the second magnetic component is a pole piece, and the third magnetic component is a yoke, An acoustic transducer wherein an inner periphery of the first coil is located substantially on an inner peripheral surface of the first magnetic component. 5. The acoustic transducer according to claim 1, wherein said first magnetic component is a pole piece, said second magnetic component is a plate, and said third magnetic component is a yoke. An acoustic transducer in which an outer periphery of a first coil is located substantially on an outer peripheral surface of the first magnetic component. 6. An acoustic transducer according to claim 1, wherein said first coil is constituted by a plurality of coils divided and wound, and said plurality of coils are connected in series or in parallel. 7. The acoustic converter according to claim 2, wherein said drive coil is driven by a digital audio signal.