JP7202249B2 - Electroacoustic transducer - Google Patents

Description

The present disclosure relates to electroacoustic transducers mainly used for earphones, headphones, and the like.

2. Description of the Related Art In recent years, portable music players, mobile terminals such as smartphones, and the like have become popular for high-quality music reproduction using digital sound sources, and there is a demand for compact earphones and headphones (hereinafter referred to as earphones, etc.) with high sound quality.

In order to improve the sound quality of earphones and the like, various improvements have been made to electroacoustic transducers (so-called driver units). For example, in Patent Document 1, in an electroacoustic transducer for a speaker, a ring-shaped first permanent magnet (magnet) is arranged in front of a disk-shaped first yoke, and the first permanent magnet A ring-shaped second yoke is disposed on the front surface of the second yoke, a ring-shaped second permanent magnet having a polarity opposite to that of the first permanent magnet is disposed on the front surface of the second yoke, and the first yoke A cylindrical center pole facing the inner peripheral surfaces of the first permanent magnet and the second yoke via a magnetic gap is disposed at the center of the front surface of the yoke, and the second permanent magnet and the second permanent magnet are disposed on the front surface of the center pole. discloses a magnetic circuit for a speaker in which a third permanent magnet of opposite polarity is arranged. In the technique described in Patent Document 1, by adopting such a magnetic circuit configuration, a closed magnetic circuit is formed to increase the magnetic flux density in the air gap of the magnetic gap, thereby driving the voice coil arranged in the magnetic gap. It is designed to increase power and improve sound quality.

In patent document 2, in a speaker device having an outer magnet type magnetic circuit, a support frame provided around the magnetic circuit is provided with a ventilation part on the side surface, and a cylindrical hollow part is provided at the center of the yoke of the magnetic circuit. is disclosed. In Patent Document 2, a large magnet can be produced without being restricted by the size of the diaphragm by providing a ventilation part on the side part of the support frame to release the air between the back of the edge part of the diaphragm and the magnetic circuit. It is described that it can be used and that the sensitivity can be improved.

Patent No. 3902066 Patent No. 4233745

However, providing a plurality of permanent magnets and a plurality of yokes as in Patent Document 1 increases the number of parts, making it difficult to reduce the size of the electroacoustic transducer. Moreover, there arises a problem that the manufacturing cost of the electroacoustic transducer increases as the number of parts increases.

Furthermore, in Patent Document 2, a hollow portion (vent hole) is formed through the center of the yoke of the magnetic circuit, which reduces the radial thickness of the center pole by the amount of the hollow portion. When the thickness of the center pole is reduced in this way, the magnetic resistance increases accordingly, and the magnetic flux density between the center pole and the plate attached to the top of the magnet (magnetic gap) decreases, improving acoustic characteristics. may be hindered. Furthermore, in Patent Document 2, in order to form the hollow portion of the center pole, there is a problem that processing time is required for penetrating the entire thickness direction of the center pole.

The present disclosure has been made in order to solve such problems, and the purpose thereof is to prevent an increase in the number of parts and to improve the magnetic flux density of the magnetic gap by easy processing, reduce the size and size. An object of the present invention is to provide an electroacoustic transducer capable of realizing improvement in acoustic characteristics.

To achieve the above object, an electroacoustic transducer according to the present disclosure comprises a cylindrically wound coil, a diaphragm connected to the coil, and a cylindrical shape having a diameter larger than that of the coil. a magnet arranged coaxially with the coil; an annular pole piece arranged on the outer peripheral side of the coil and connected to one pole side of the magnet; and a tip side arranged on the inner peripheral side of the coil, A center pole having a conical portion whose diameter expands toward the root side along the axial direction of the coil, and a center pole that expands radially outward from the root of the center pole and is connected to the other pole side of the magnet on one surface. and a plate member attached to the other surface opposite to the one surface of the flat plate portion, the flat plate portion having a space on the one surface side and a space on the other surface side. A ventilation hole communicating with a space is formed, and the plate member partitions the space on the other side communicating with the ventilation hole on the other side of the flat plate portion, and separates the space on the other side. A ventilation hole is formed to communicate with the outside .

In the electroacoustic transducer described above, the center pole has a range in which the tip of the conical portion faces the inner peripheral surface of the coil in the radial direction, and the diameter of the root side of the conical portion extends to the outer periphery of the coil. It may be formed on the outer peripheral side of the surface.

Moreover, in the electroacoustic transducer described above, a plurality of vent holes may be formed in the flat plate portion.

Further, in the electroacoustic transducer described above, the plate member may be disc-shaped with a stepped edge, and the space on the other side may be formed by the stepped portion of the plate member.
Further, in the electroacoustic transducer described above, the opening on the one surface side of the ventilation hole of the flat plate portion may be partially closed by the magnet.
Further, in the electroacoustic transducer described above, the center pole may have a part of its root portion cut along the shape of the ventilation hole of the yoke.

According to the electroacoustic transducer according to the present disclosure using the above means, it is possible to prevent an increase in the number of parts and to improve the magnetic flux density of the magnetic gap through easy processing, thereby realizing miniaturization and high sound quality.

1 is an exploded perspective view of an electroacoustic transducer according to an embodiment of the present disclosure, viewed from one side in the central axis O direction; FIG. FIG. 4 is an exploded perspective view of the electroacoustic transducer according to the embodiment of the present disclosure, viewed from the other side in the central axis O direction; (a) A top view of an electroacoustic transducer, (b) a side view of an electroacoustic transducer, and (c) a bottom view of an electroacoustic transducer. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3(a); (a) is a magnetic flux distribution diagram in the magnetic circuit of the present embodiment, and (b) is a magnetic flux distribution diagram in a magnetic circuit using a center pole whose entire area is cylindrical as a comparative example. 6 is a graph showing magnetic flux densities between a and b in FIGS. 5(a) and 5(b); FIG.

An embodiment of the present disclosure will be described below based on the drawings.

FIG. 1 is an exploded perspective view of an electroacoustic transducer according to an embodiment of the present disclosure viewed from one side in the central axis O direction, and FIG. 2 is an electroacoustic transducer according to an embodiment of the present disclosure viewed from the other side in the central axis O direction. 3 is (a) a top view of the electroacoustic transducer, (b) a side view of the electroacoustic transducer, (c) a bottom view of the electroacoustic transducer, and FIG. 4 is a line IV-IV. It is a sectional view along. The configuration of the electroacoustic transducer will be described below with reference to these figures.

The electroacoustic transducer 1 mainly includes a diaphragm assembly 3, a magnetic circuit 4 for driving the diaphragm assembly 3, and a plate member connected to the magnetic circuit 4, inside a cylindrical case 2 forming an outer shell. 5, a screen 6 provided inside the plate member 5, and a terminal 7 provided on the outer surface of the plate member 5 are provided. The electroacoustic transducer 1 is mounted on, for example, earphones or headphones.

Specifically, the cylindrical case 2 has an outer shape at one side end in the direction of the central axis O that gradually decreases in diameter toward the tip, and a sound emitting opening 2a is formed in one end face. there is On the other hand, the other end surface of the case 2 remains open.

In the diaphragm assembly 3, a diaphragm 10 made of pulp, film, or the like is supported by an annular frame 11 at its periphery. A flat circular center surface 10a is formed in the center of the diaphragm 10, and an annular edge portion 10b that rises to one side in the central axis O direction is formed on the periphery of the center surface 10a. A voice coil 12 (coil) wound in a cylindrical shape coaxial with the central axis O is connected to the rear surface of the peripheral portion of the central surface 10a of the diaphragm 10 (the other side surface in the direction of the central axis O). , and the vibration of the voice coil 12 is transmitted to the diaphragm 10 . From the voice coil 12, two lead wires 12a of wires forming the coil extend outward.

The magnetic circuit 4 is composed of a magnet 20, a pole piece 21 connected to one polarity of the magnet 20, and a yoke 22 connected to the other polarity. The pole piece 21 and the yoke 22 are made of magnetic material.

The magnet 20 has a cylindrical shape with a diameter larger than that of the voice coil 12 and is arranged coaxially with the voice coil 12 . The magnet 20 has polarities in the central axis O direction, one polarity (for example, S pole) on one side of the central axis O direction, and the other polarity (for example, N pole) on the other side of the central axis O direction. have.

The pole piece 21 has an annular shape and is arranged on the outer peripheral side of the voice coil 12 . A stepped portion 21a with which the frame 11 of the diaphragm assembly 3 engages is formed on the peripheral portion of the surface of the pole piece 21 on one side in the direction of the central axis O. As shown in FIG. Also, the pole piece 21 is formed with a notch 21b through which the two lead wires 12a of the voice coil 12 are passed.

The yoke 22 has a disk-like shape with a center pole 30 extending along the direction of the central axis O and a center pole 30 extending radially outward from the base of the center pole 30 and connected to the magnet 20 . and a flat plate portion 31.

The center pole 30 is formed from a cylindrical portion 30a on the tip side and a conical portion 30b on the root side. The diameter of the conical portion 30b increases along the direction of the central axis O from the tip, which is the boundary with the cylindrical portion 30a, toward the root side (the other side in the direction of the central axis O).

Specifically, the conical portion 30b expands in diameter from the tip side to the base side, and the diameter expands to be larger than that of the voice coil 12. 30 is inclined within a range that does not interfere. More specifically, as shown in FIG. 4, the tip of the conical portion 30b is located at substantially the same position as the other end of the voice coil 12 in the central axis O direction. Note that the tip position of the conical portion 30b is not limited to this position, and may be any position that faces the inner peripheral surface of the voice coil 12 in the radial direction. The diameter of the base of the conical portion 30b is formed on the outer peripheral side of the outer peripheral surface of the voice coil 12, and is formed close to the inner diameter of the magnet 20 in the present embodiment.

The flat plate portion 31 has a disc shape with a slightly larger diameter than the outer diameter of the magnet 20 . A space A on one side of the flat plate portion 31 connected to the magnet 20 (one side surface in the direction of the central axis O) and a space A on the one side of the flat plate portion 31 at three positions over the root portion of the center pole 30 . are formed to communicate with the space B on the other side (the other side in the direction of the central axis O). Each ventilation hole 31a is a circular hole, and the base portion of the center pole 30 is partially cut along the shape of each ventilation hole 31a. A part of the opening on one side of each ventilation hole 31 a is blocked by the magnet 20 .

In addition, an arc-shaped notch 31b is formed in a part of the peripheral edge of the flat plate portion 31 for passing two lead wires 12a of the voice coil 12 therethrough.

The plate member 5 has a disc shape with a stepped edge and is attached to the other side surface of the flat plate portion 31 of the yoke 22 . Thus, the plate member 5 defines a space B that communicates with the ventilation holes 31a on the other surface side of the flat plate portion 31 of the yoke 22. As shown in FIG. A vent hole 5a is formed in the central position of the plate member 5 for communicating the internal space and the outside. In addition, an arc-shaped notch 5b is formed in a part of the peripheral edge of the plate member 5 for passing two lead wires 12a of the voice coil 12 therethrough.

The screen 6 is a circular film-like air-permeable acoustic resistance material, and is provided in the space formed by the plate member 5 so as to cover the ventilation holes 5a. An annular double-sided tape 6a is attached to the other side of the screen 6, and the screen 6 is attached to the plate member 5 via the double-sided tape 6a.

The terminal 7 is a circular plate member having a center hole 7a formed therein. One surface of the terminal 7 in the direction of the central axis O is adhered to the plate member 5, and an electrode 7b is formed on the surface of one side in the direction of the central axis O. ing. Also, an arc-shaped notch 7c is formed in a part of the peripheral edge of the terminal 7 for passing two lead wires 12a of the voice coil 12 therethrough.

The cutout portion 21b of the pole piece 21, the cutout portion 31b of the flat plate portion 31 of the yoke 22, the cutout portion 5b of the plate member 5, and the cutout portion 7c of the terminal 7 are all positioned substantially on the same line parallel to the direction of the central axis O. The two lead wires 12a of the voice coil 12 are connected to the electrode 7b of the terminal 7 through the notches 21b, 31b, 5b and 7c. Although not shown, a UV adhesive is applied in the circumferential direction to the annular gap between the case 2 and the plate member 5, and the UV adhesive seals the gap between the case 2 and the plate member 5. It is Two lead wires 12a passing through the notch 5b of the plate member 5 are also adhered with a UV adhesive. Therefore, in the electroacoustic transducer 1 configured as described above, the space on the back side of the diaphragm 10 is a closed space extending to the ventilation hole 5a of the plate member 5 through the screen 6. FIG.

In the electroacoustic transducer 1 configured as described above, when an electric signal is sent to the electrode 7b of the terminal 7, the voice coil 12 is energized through the lead wire 12a, and the voice coil 12 is energized in response to the electric signal. The vibration causes the diaphragm 10 to vibrate, and sound is emitted from the sound emission opening 2a.

In the electroacoustic transducer 1 according to this embodiment, the center pole 30 of the yoke 22 is formed with the conical portion 30b, thereby ensuring the maximum radial thickness of the center pole 30. As shown in FIG. In other words, since the center pole 30 can be thickened in the portion near the magnet 20, the magnetic resistance can be reduced more than the structure in which a ventilation hole is formed in the center of the center pole as in Patent Document 2 above. can be done.

By reducing the magnetic resistance of the yoke 22 in this way, the magnetic flux density of the magnetic gap G (shown in FIG. 4) between the center pole 30 and the pole piece 21 can be improved.

Here, FIG. 5 and FIG. 6 show the results of simulating the configurations of this embodiment and the comparative example. FIG. 5 shows (a) a magnetic flux distribution diagram in the magnetic circuit of this embodiment, and (b) a magnetic flux distribution diagram in a magnetic circuit using a center pole having a cylindrical shape all over as a comparative example, and FIG. 5(a) and (b) are graphs showing the magnetic flux densities between a and b respectively. As shown in FIG. 5A, in the yoke 22 of this embodiment, the magnetic flux density is concentrated on the tip side of the center pole 30 because the conical portion 30b is closer to the magnet 20 toward the root side. Therefore, the magnetic flux density between the cylindrical portion 30a at the tip of the center pole 30 where the voice coil 12 is located and the pole piece 21 is increased, and the driving force of the voice coil 12 is improved.

On the other hand, as shown in FIG. 5(b), in a yoke 22' having a shape in which a cylindrical center pole 30' protrudes from the center of a flat plate portion 31', magnetic flux is generated in the central portion of the center pole 30' in the direction of the central axis O. Density is concentrated. Therefore, with such a yoke 22', it is difficult to increase the magnetic flux density in the portion where the voice coil 12 is located.

Furthermore, as shown in FIG. 6, the magnetic flux density between a and b in FIGS. 5(a) and 5(b) is displayed. It can be seen that the magnetic flux density is higher than in the comparative example.

As described above, according to the electroacoustic transducer 1 of the present embodiment, the driving force of the voice coil 12 can be improved, and better acoustic characteristics can be obtained. In addition, since the electroacoustic transducer 1 of the present embodiment does not require any particular addition of parts or major changes in the layout of each part, the electroacoustic transducer 1 can be miniaturized while its acoustic characteristics are improved. can be made

Further, in the electroacoustic transducer 1 of the present embodiment, the conical portion 30b is formed in a range in which the voice coil 12 and the center pole 30 do not interfere when the center pole 30 of the yoke 22 vibrates by energizing the voice coil 12. Therefore, the magnetic resistance can be lowered without disturbing the vibration of the voice coil 12 .

Furthermore, since the tip of the conical portion 30b is in a range that faces the inner peripheral surface of the voice coil 12 in the radial direction, and the diameter of the root side of the conical portion 30b reaches the inner diameter of the magnet 20, the diameter of the center pole 30 is It is possible to secure the maximum thickness in the direction and reduce the magnetic resistance to the maximum.

In addition, since the air hole 31a is formed in the flat plate portion 31 of the yoke 22, the air hole 31a can be processed in a shorter processing time than when the center of the center pole 30 is drilled. Since the thickness of the center pole 30 is not reduced, the magnetic resistance of the center pole 30 is not increased.

Further, by forming a plurality of ventilation holes 31a, even if the magnet 20 and the yoke 22 are misaligned and one of the ventilation holes 31a is blocked by the magnet 20, the other ventilation holes 31a can be closed. air can be reliably ventilated from the rear side of the yoke 22. Also, by increasing or decreasing the number of air holes 31a and changing the hole diameter of each air hole 31a, it is possible to easily provide a range of sound adjustment (braking).

By providing a plate member 5 in which a space communicating with each ventilation hole 31a is defined on the other surface side of the flat plate portion 31 of the yoke 22 and a ventilation hole 5a communicating between the space and the outside is formed, The sound quality of the electroacoustic transducer 1 can be easily set by the volume of the space and the size of the vent hole 5a.

As described above, according to the electroacoustic transducer 1 according to the present embodiment, it is possible to prevent an increase in the number of parts and to improve the magnetic flux density of the magnetic gap G through easy processing, thereby realizing miniaturization and high sound quality. .

Although the description of the embodiment of the present disclosure is finished above, the aspect of the present disclosure is not limited to this embodiment.

For example, in the electroacoustic transducer 1 of the above embodiment, the flat plate portion 31 of the yoke 22 has three vent holes 31a, but the number of vent holes is not limited to this, and may be one or four. One or more may be formed.

Further, the center pole 30 of the yoke 22 of the magnetic circuit 4 in the above-described embodiment is composed of a cylindrical portion 30a on the tip side and a conical portion 30b on the root side, but the center pole only needs to have a conical portion. It is not limited to this shape. For example, the center pole may have a shape that connects from the base of the conical portion to the flat plate portion through the columnar portion. The cylindrical portion extending from the base of the conical portion may have the same diameter as the base of the conical portion, or may be a column having a diameter larger than the diameter of the base of the conical portion. By engaging the outer diameter of the cylindrical portion on the root side of the center pole with the inner diameter of the magnet, the yoke and the magnet can be easily aligned and assembled. Alternatively, the center pole of the yoke may consist of only the conical portion.

REFERENCE SIGNS LIST 1 electroacoustic transducer 2 case 3 diaphragm assembly 4 magnetic circuit 5 plate member 5a ventilation hole 5b notch 6 screen 7 terminal 7a center hole 7b electrode 7c notch 10 diaphragm 11 frame 12 voice coil (coil)
20 Magnet 21 Pole Piece 22 Yoke 30 Center Pole 30a Cylindrical Part 30b Conical Part 31 Flat Plate Part 31a Air Vent 31b Notch

Claims (6)

a cylindrically wound coil;
a diaphragm connected to the coil;
a magnet having a cylindrical shape with a diameter larger than that of the coil and arranged coaxially with the coil;
an annular pole piece arranged on the outer peripheral side of the coil and connected to one pole side of the magnet;
a center pole having a conical portion whose distal end side is disposed on the inner peripheral side of the coil and whose diameter expands toward the root side along the axial direction of the coil; a yoke having a flat plate portion connected to the other pole side of the magnet on one surface ;
a plate member attached to the other surface opposite to the one surface of the flat plate portion;
with
The flat plate portion is formed with a ventilation hole communicating between the space on the one side and the space on the other side,
The plate member defines a space on the other surface that communicates with the ventilation hole on the other surface of the flat plate portion, and has a ventilation hole that communicates the space on the other surface with the outside. there is
An electroacoustic transducer characterized by: The tip of the conical portion of the center pole is in a range that faces the inner peripheral surface of the coil in the radial direction, and the diameter of the root side of the conical portion is formed on the outer peripheral side of the outer peripheral surface of the coil. An electroacoustic transducer according to claim 1, characterized in that: 3. The electroacoustic transducer according to claim 1, wherein a plurality of air holes are formed in said flat plate portion. The plate member has a disc shape with a stepped edge,
4. The electroacoustic transducer according to claim 1, wherein the space on the other side is formed by the step formed on the plate member. 5. The electroacoustic transducer according to any one of claims 1 to 4, wherein the opening of the ventilation hole of the flat plate portion on the one side is partially closed by the magnet. 6. The electroacoustic transducer according to any one of claims 1 to 5, wherein said center pole has a base portion which is partly shaved along the shape of said yoke's ventilation hole.

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