JP3161678B2 - Magnetic drive device and speaker using magnetic drive device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic drive device in which a vibrating body is driven by a magnetic field generated by a magnet and a current flowing through a coil, and a speaker in which a diaphragm is driven using the magnetic drive device. About.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing a conventional example of a magnetic drive device A used for a dynamic speaker or the like. The magnetic drive device A includes a yoke 1 formed in a ring shape having an axis in a Y-axis direction indicating a vibration direction;
A pair of ring-shaped magnetic bodies 2 and 3 facing the outer peripheral surface of the yoke 1 at two locations separated in the axial direction;
And a ring-shaped magnet 4 sandwiched therebetween.
The yoke 1 and the magnetic bodies 2 and 3 are both formed of a magnetic material having high magnetic permeability such as soft iron and ferrite.

A gap G1 formed of a cylindrical space is formed at the opposing portion between the yoke 1 and the magnetic body 2, and a gap G2 formed of a cylindrical space is formed at the opposing portion of the yoke 1 and the magnetic body 3. I have. The cylindrical bobbin 6 is connected to a cone-shaped diaphragm or the like.
(Voice coils) C1 and C2 provided in the gaps G1 and G2, respectively.

[0004] The magnet 4 has magnetic anisotropy in the Y-axis direction,
The joining surface 5a side is an N pole, and the joining surface 5b side is an S pole. The magnetic flux generated by the magnet 4 travels from the magnetic body 2 to the yoke 1 via the gap G1.
After that, it goes to the magnetic body 3. An electromagnetic force acts on the coils C1 and C2 by the voice current applied to the coils C1 and C2 and the magnetic flux traversing the gaps G1 and G2, and the bobbin 6
At the same time, the diaphragm vibrates in the Y direction.

[0005]

In the conventional magnetic drive device A shown in FIG. 5, the joint surface 5a between the magnet 4 and the magnetic body 2 and the joint surface 5b between the magnet 4 and the magnetic body 3 are both Y-axis. The plane is orthogonal to the direction. Then, the vertical magnetic field in the Y-axis direction of the magnet 4 is converted into a horizontal magnetic field in a direction orthogonal to the Y-axis direction by the magnetic bodies 2 and 3 of the high magnetic permeability material.

In this conventional example, since the joining surfaces 5a and 5b are planes orthogonal to the Y axis, the efficiency of conversion from the vertical magnetic field of the magnet 4 to the horizontal magnetic field to the magnetic bodies 2 and 3 is low, and the coils C1 and C2 are inefficient.
The edge of the joint surface 5a on the outer surface side opposite to C2 and the joint surface 5
Leakage (leakage magnetic flux) H1 of the line of magnetic force between the edges of b increases. As a result, the magnetic flux density traversing the gaps G1 and G2 decreases, and the efficiency of the action of the electromagnetic force on the voice current applied to the coils C1 and C2 decreases. That is, magnet 4
The energy of the magnetic field is not used effectively.
Therefore, in order to perform highly sensitive driving, the magnet 4
Must be large, and as a result, the magnetic drive device A and the speaker become large and heavy.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic drive device capable of efficiently performing magnetic drive with a small magnet by effectively utilizing the magnetic field energy of the magnet. I have.

It is another object of the present invention to provide a small, lightweight speaker having good sensitivity by using the magnetic drive device.

[0009]

According to the present invention, there is provided a magnetic drive device comprising: a yoke made of a magnetic material; a pair of magnetic bodies opposed to two places of the yoke via a gap; , A coil positioned in the gap, and a vibrating body that vibrates due to a driving force applied to the coil, and the joint surfaces of the pair of magnetic bodies and the magnet are separated from the coil. The magnets are characterized in that one of the joining surfaces has an N pole and the other has an S pole on the other joining surface.

[0010] Alternatively, a yoke made of a magnetic material, a pair of magnets facing two places of the yoke via a gap, a magnetic body sandwiched between the pair of magnets, and a magnet positioned in the gap. A coil, and a vibrating body that vibrates by a driving force applied to the coil, and the joining surfaces of the pair of magnets and the magnetic material are inclined surfaces in a direction in which the joining surfaces move away from each other as the coil moves away from the coil. , One magnet has an N pole on the gap side and an S pole on the joining surface side,
The other magnet has an S pole on the gap side and an N pole on the joining surface side.

In a preferred example, as shown in FIG. 2, when the width of the gap and the width of the magnetic body (width in the vibration direction (Y-axis direction) of the vibrating body) are W, the magnetic body and the magnet Is formed so as to be a continuous inclined surface from one side surface to the other side surface in the width W direction of the magnetic body. Further, as shown in FIG. 3, when the width of the gap and the width of the magnet are W, the joining surface between the magnet and the magnetic body is continuous from one side in the width W direction to the other side of the magnet. It is formed so as to be an inclined surface.

Further, when the yoke, the magnetic body and the magnet are ring-shaped, the joining surface is a tapered surface.

The magnetic drive device of the present invention is used for focus and tracking drive of an objective lens by an optical head and other various devices using electric / vibration conversion.
Preferably, a magnetic drive is used for the speaker.

A speaker using the magnetic drive device is
The vibrating body that vibrates by the driving force given to the coil is a cone-shaped vibrating plate. The yoke, magnet, and magnetic body are ring-shaped, and a cylindrical gap is formed. It will be located in.

[0015]

According to the magnetic drive device of the present invention, as shown in FIG. 2, a magnet is sandwiched between a pair of magnetic bodies facing the yoke.
A gap is formed between the yoke and the pair of magnetic bodies.
The magnet generates a vertical magnetic field in the vibration direction of the vibrating body, and this vertical magnetic field is converted into a horizontal magnetic field in the gap direction by the magnetic body. Here, the joining surface between the pair of magnetic bodies and the magnet is an inclined surface in a direction in which the joining surfaces move away from each other as the distance from the coil increases. That is, the joining surface is a surface inclined with respect to both the direction of the longitudinal magnetic field generated by the magnet and the direction of the transverse magnetic field directed to the gap direction (the direction in which the yoke and the magnetic body are arranged). Therefore, the efficiency with which the vertical magnetic field of the magnet is converted into the horizontal magnetic field in the magnetic body is improved, and the leakage of the magnetic field lines in the space opposite to the coil is reduced. Therefore, the magnetic flux density across the gap is increased, and high-sensitivity magnetic driving is possible.

Further, since the efficiency of converting the direction of the magnetic field is good and the efficiency of using the energy of the magnetic field is high, the magnet can be made small and lightweight.

As shown in FIG. 3, in a magnetic drive device in which a pair of magnets face a yoke and a magnetic body is sandwiched between the magnets, a gap direction (a direction in which the yokes and the magnets are arranged) is formed by the pair of magnets. The transverse magnetic field is generated, and the magnetic flux traverses the gap between the magnet and the yoke, but on the magnet side, the transverse magnetic field is converted into a longitudinal magnetic field in the magnetic body sandwiched between the two magnets, and the magnetic field between the magnets A circuit is formed. Also in this case, the joint surface between the magnet and the magnetic body is formed to be inclined with respect to both the direction of the horizontal magnetic field and the direction of the vertical magnetic field that is the direction in which the pair of magnets are arranged (the driving direction of the vibrating body). Therefore, the efficiency with which the horizontal magnetic field of the magnet is converted into a vertical magnetic field in the magnetic body is improved, and the leakage magnetic flux between the magnets on the side opposite to the coil is reduced. Therefore,
The utilization efficiency of the magnetic flux in the gap is increased, and high-sensitivity driving of the vibrator can be performed.

In the speaker using the above magnetic drive device, the driving efficiency of the diaphragm with respect to the voice current is improved,
High sensitivity. Further, since the utilization efficiency of the magnetic field lines is improved, the magnet can be reduced in size and weight, and the speaker can be reduced in size, thickness and weight.

[0019]

Embodiments of the present invention will be described below. FIG. 1 is a cross-sectional view showing a dynamic speaker used for a vehicle or the like as one embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a magnetic drive device used in the speaker. In the speaker shown in FIG. 1, the frame 11 is formed by injection molding of a plastic material such as ABS. Therefore, the whole speaker is lightweight. The frame 11 may be formed by die-casting with a lightweight alloy other than plastic, such as an aluminum alloy or a zinc alloy.

The diaphragm 12 is a conical cone made of paper or the like, and a spherical dome portion 13 is joined to the conical head 12a. The edge of the conical bottom portion 12b of the diaphragm 12 is
Is joined to the opening edge 11a. Deformation joint 14
Is provided circumferentially separately from the diaphragm 12 along the edge of the conical bottom portion 12b, and has a semicircular shape (semicylindrical shape) having a predetermined radius of curvature.

A damper 15 is provided between the conical head 12a of the diaphragm 12 and the inner surface of the frame 11. This damper has multiple waveforms formed concentrically. The diaphragm 12 is connected to the deformation joint 1.
Due to the deformation of the damper 4 and the damper 15, it is supported so as to be able to vibrate in the Y axis direction. The bottom 11b of the frame 11 and the diaphragm 1
A magnetic drive device A1 is provided between the first and second conical heads 12a.

As shown in FIG. 2, the magnetic drive device A1
It has a ring-shaped opposed yoke 21. The opposed yoke 21 is formed of a magnetic material having a high magnetic permeability such as soft ferrite or soft iron. On the outer peripheral surface of the yoke 21,
The inner peripheral surfaces of the ring-shaped magnetic bodies 22 and 23 face each other at a predetermined interval in the Y-axis direction which is the vibration direction of the diaphragm 12 (vibrating body). The ring-shaped magnetic bodies 22 and 23 are formed of a magnetic material having a high magnetic permeability such as soft ferrite or soft iron similar to the yoke 21. The center line OO is the center of the opposing portion between the outer peripheral surface of the opposing yoke 21 and the inner peripheral surface of the magnetic body 22 and the opposing portion of the outer peripheral surface of the opposing yoke 21 and the inner peripheral surface of the magnetic body 23. The gaps G1 and G2, which form a cylindrical space, are formed.

The coil C1 is located in the gap G1, and the coil C2 is located in the gap G2. Both coils C1 and C
2 is fixed to a cylindrical bobbin 19, and this bobbin 19 is joined to a conical head 12a of the diaphragm 12 which is a vibrating body driven by the coils C1 and C2. The energizing direction (winding direction) of the coils C1 and C2 is a direction orthogonal to the paper surface, and the voice current flowing through the coil C1 and the coil C
2, an electromagnetic force (driving force) acts on the coils C1 and C2 in the same direction on the Y axis.

A ring-shaped magnet 24 is interposed between the pair of magnetic bodies 22 and 23. This magnet 24 is a bonded magnet (plastic magnet) in which magnet powder is bonded with resin.
Or a sintered magnet. The magnet 24 is connected to the diaphragm 12
The (vibrating body) has magnetic anisotropy in the vibration direction (Y-axis direction). For example, the upper bonding surface 25a side in the drawing is the N pole, and the lower bonding surface 25b side in the drawing is the S pole. This magnetization direction may be reversed.

Here, the joining surface 25a between the magnetic body 22 and the magnet 24 and the joining surface 25b between the magnetic body 23 and the magnet 24 are:
As the distance from the coils C1 and C2 increases, the joining surfaces are inclined in a direction away from each other.
That is, the joining surfaces 25a and 25b are inclined surfaces that are inclined with respect to both the direction of the vertical magnetic field of the magnet 24 (the Y-axis direction) and the direction of the horizontal magnetic field that is the direction in which the gaps G1 and G2 face each other (the horizontal direction in the drawing). It has become.

In a preferred embodiment, as shown in FIG. 2, when the width of the gap and the width of the magnetic members 22 and 23 in the Y-axis direction are W, the inclined surfaces 25a and 25b 22 and 23 are formed so as to cross over the entire width dimension W. In other words, the magnetic members 22 and 23 are not formed with surfaces extending in the Y-axis direction at the upper and lower edges (a) at the outer peripheral side of the magnetic drive device A1, that is, at the edges (a). Magnetic body 2
The inclined surfaces of the magnets 2 and 23 and the magnet 24 face each other. Further, since both the magnetic bodies 22 and 23 and the magnet 24 are ring-shaped, the joining surfaces 25a and 25b are both tapered surfaces.

Next, the operation of the magnetic drive device A1 and the speaker will be described. Magnetic drive device A1 shown in FIG.
Then, the vertical magnetic field in the Y-axis direction of the magnet 24 is converted by the magnetic bodies 22 and 23 of the high magnetic permeability material into a horizontal magnetic field directed to the gaps G1 and G2. However, since the joining surfaces 25a and 25b between the magnetic bodies 22 and 23 and the magnet 24 are inclined with respect to both the vertical magnetic field and the horizontal magnetic field, the conversion efficiency from the vertical magnetic field to the horizontal magnetic field is improved. . Therefore, the leakage (leakage magnetic flux) H2 of the lines of magnetic force between the edges (a) on the surface opposite to the coil of the magnet 24 is extremely reduced.

In particular, as shown in FIG.
5a is an inclined surface that traverses the magnetic bodies 22 and 23 over the entire length of the width dimension W.
The conversion from the vertical magnetic field to the horizontal magnetic field by a and 25b is effectively exerted. Therefore, the magnetic bodies 22, 23
The magnetic flux density in the transverse magnetic field in the inside increases, and the gaps G1 and G
2 can be given a magnetic flux effectively. That is, the efficiency of using the energy of the magnetic field of the magnet 24 is improved.

When a voice current is applied to the coils C1 and C2 in a direction perpendicular to the plane of the drawing, the voice current and the gap G
1, due to the transverse magnetic field at G2, the coils C1 and C2 have Y
An axial driving force is provided. Since the utilization efficiency of the magnetic field of the magnet 24 is high and the degree of magnetic flux concentration in the gaps G1 and G2 is high, a highly sensitive driving force is applied to the coils C1 and C2.

In the speaker shown in FIG. 1, coils C1, C
Since the diaphragm 12 is driven via the bobbin 19 by the driving force given to the speaker 2, the sensitivity of the speaker is improved. Further, since the utilization efficiency of the magnetic field of the magnet 24 is good,
It is possible to make the magnet 24 small and lightweight,
As a result, the size of the speaker is reduced, and the frame 11 is also lightweight, so that the entire speaker is very light.

FIG. 3 shows a second embodiment of the magnetic drive device used for the speaker. In the magnetic drive device A2, magnets 31 and 32 are provided to face the outer peripheral surface of the opposing yoke 21 at a constant interval in the Y-axis direction.
A magnetic body 33 is sandwiched between the two magnets 31 and 32. The magnets 31 and 32 are bond magnets and the like, and the magnetic body 33 is made of a magnetic material having high magnetic permeability such as soft ferrite and soft iron.

In this embodiment, the joint surface 34a between the magnet 31 and the magnetic member 33 and the joint surface 34b between the magnet 32 and the magnetic member 33 are arranged such that the opposing surfaces are separated from each other as the distance from the coils C1 and C2 increases. It is a slope. 2, when the width of the magnets 31 and 32 in the Y-axis direction is W, the joint surfaces 34a and 34b cross the magnets 31 and 32 over the entire length in the width W direction. It has an inclined surface. One magnet 31 has an N pole on the gap G1 side and an S pole on the joining surface 34a side, and the other magnet 32 has an S pole on the gap G2 side and an N pole on the joining surface 34b side.

In the magnetic driving device A2, the magnets 31 and 3
Numeral 2 generates a transverse magnetic field orthogonal to the Y-axis direction. Between the magnets 31 and 32, the magnetic body 33 converts the transverse magnetic field into a vertical magnetic field directed in the Y-axis direction to form a magnetic circuit. Here, the joint surface 34a between the magnet 31 and the magnetic body 33
In addition, since the joint surface 34b between the magnet 32 and the magnetic body 33 is a surface inclined with respect to the directions of the horizontal magnetic field and the vertical magnetic field, the conversion efficiency from the horizontal magnetic field to the vertical magnetic field is improved, and the coils C1, C2 The leakage (leakage magnetic flux) H3 of the lines of magnetic force between the magnets 31 and 32 on the side opposite to the above can be reduced. Therefore, similarly to the embodiment shown in FIG. 2, the utilization efficiency of the magnetic field is improved, and high-sensitivity magnetic driving is possible.

In the magnetic circuit shown in FIG.
When molding 1 and 32 with a bond magnet (plastic magnet), what is called insert molding is possible in which the magnets 31 and 32 are molded by injection molding by inserting the magnetic body 33 into a mold. In this case, the mold is Y
When separating in the axial direction, the portions of the magnets 31 and 32 become an obstacle, and it is necessary to provide an insert.

However, as shown in FIG.
By providing a spacer 35 of a non-magnetic material between
When the magnets 31 and 32 are insert-molded, mold separation in the Y-axis direction becomes easy. The spacer 35 is made of metal, heat-resistant resin, ceramic, or the like. The spacer 35 is fixed to the magnetic body 33 in advance, and the magnets 31 and 32 are insert-molded to both. This insert molding can also be performed with the one shown in FIG.
3 may be connected in advance by a spacer, and the magnet 24 may be formed by insert molding.

In each of the above embodiments, the bobbin 1
9 is provided with a yoke 21 on the inner circumference side and a magnet and a magnetic body on the outer circumference side. Conversely, a magnet and a magnetic body are provided on the inner circumference side of the bobbin 19 and the yoke is provided on the outer circumference side. May be used. Further, in the above embodiment, the speaker having the conical diaphragm 12 is described as an example, but the sound vibration of the diaphragm may be of a type that vibrates the space in the horn. In addition, the magnetic driving devices A1, A
2 can be used for various devices other than the speaker that convert current into vibration.

[0037]

As described above, according to the present invention, the efficiency of converting the direction of the magnetic field of the magnet to the direction of the magnetic field of the magnetic material is improved, the leakage magnetic flux is reduced, and the magnetic flux can be concentrated in the gap. Therefore, high-sensitivity driving becomes possible.

Further, since the magnetic field conversion efficiency is good, the magnet can be made small and lightweight, and thus the magnetic drive device and the speaker can be made small and lightweight.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a magnetic drive device and a speaker using the same according to the present invention;

FIG. 2 is an enlarged sectional view of the magnetic drive device shown in FIG. 1;

FIG. 3 is a sectional view showing another embodiment of the magnetic drive device;

FIG. 4 is a cross-sectional view showing a structure of a magnetic drive device suitable for insert molding.

FIG. 5 is a cross-sectional view showing a magnetic drive device provided in a conventional speaker;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Frame 12 Vibration plate (vibration body) 14 Deformation joint 15 Damper 19 Bobbin 21 Yoke 22, 23, 33 Magnetic body 24, 31, 32 Magnet 25a, 25b, 34a, 34b Joining surface A1, A2 Magnetic drive device C1, C2 Coil G1, G2 Gap

Claims (3)

(57) [Claims] A yoke made of a magnetic material;
A pair of magnetic bodies opposing a location via a gap, a magnet sandwiched between the pair of magnetic bodies, a coil positioned in the gap, and a vibrating body vibrating by a driving force applied to the coil And the joining surfaces of the pair of magnetic bodies and the magnets are inclined surfaces in which the joining surfaces are separated from each other as the coil is separated from the coil,
The magnet has an N pole on one joint surface and an S pole on the other joint surface.
A magnetic drive device characterized in that it is a pole. A yoke made of a magnetic material;
A pair of magnets facing the location via a gap,
A magnetic body sandwiched between the pair of magnets, a coil positioned in the gap, and a vibrating body vibrating by a driving force applied to the coil; The surface is an inclined surface in which the joining surfaces move away from each other as the coil moves away. One magnet has an N pole on the gap side, an S pole on the joining surface side, and the other magnet has an S pole on the gap side and an N pole on the joining surface side. A magnetic drive device characterized in that: 3. A vibrating body using the magnetic driving device according to claim 1 or 2, wherein the vibrating body vibrates by a driving force applied to a coil is a vibrating plate, and the yoke, the magnet and the magnetic body are ring-shaped and cylindrical. A speaker in which a gap is formed and a cylindrical coil is located in the gap.