speaker

Abstract

In a speaker that drives a single diaphragm with two magnetic circuit sections, the present invention provides a compact configuration that can efficiently drive the diaphragm. [Solution] The speaker 1 includes a diaphragm 2, two magnetic circuit sections 3, 3, two voice coil bodies 4, 4 respectively inserted into the magnetic gap G between the two magnetic circuit sections 3, 3 and vibrating the diaphragm 2 by moving axially relative to the magnet 32 ​​and yoke section 31 within the magnetic gap G, and a frame section 5 that supports the yoke section 31 of the two magnetic circuit sections 3, 3 and the diaphragm 2. The two magnetic circuit sections 3, 3 are positioned such that the magnetic field of one magnetic circuit section 3 influences the magnetic field of the other magnetic circuit section 3. The magnetization directions of the magnets 32, 32 in the two magnetic circuit sections 3, 3 are opposite to each other. The directions of the currents flowing through the two voice coil bodies 4, 4 are opposite to each other as seen from the diaphragm 2.

Description

Technical Field

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[0001] The present invention relates to a speaker that vibrates one diaphragm by two voice coil bodies arranged for two magnetic circuits.

Background Art

[0002] There is known a speaker in which two voice coil bodies respectively driven by two magnetic circuits are connected to one diaphragm. For example, Patent Document 1 discloses a speaker device having two magnetic circuits provided with magnetic gaps, two voice coil bodies arranged in an inserted state in the magnetic gaps, and a long flat plate-shaped diaphragm coupled to the two voice coil bodies.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A speaker having two magnetic circuits can increase the amount of magnetic flux for driving a diaphragm compared to a speaker having one magnetic circuit, and can improve the driving efficiency. On the other hand, when the distance between the magnets of the two magnetic circuits is close, the magnetic fluxes formed by the two magnetic circuits interfere with each other, so that the leakage magnetic flux increases in each magnetic circuit. As a result, the driving efficiency of the diaphragm decreases.

[0005] Therefore, generally, in a speaker having two magnetic circuits, in order to suppress the interference of magnetic fluxes, it is necessary to increase the distance between the two magnets as in the speaker device disclosed in Patent Document 1. In this case, the size of the speaker increases in the arrangement direction of the two magnets, and it becomes difficult to configure the speaker compactly.

[0006] Therefore, in a speaker that drives a single diaphragm using two magnetic circuits, there was a need for a configuration that was both compact and capable of efficiently driving the diaphragm.

[0007] The objective of the present invention is to provide a speaker configuration that is compact and capable of efficiently driving a diaphragm, in which a single diaphragm is driven by two magnetic circuits. [Means for solving the problem]

[0008] A speaker according to one embodiment of the present invention comprises a diaphragm, two magnetic circuit sections located on the back side of the diaphragm and each having a magnet, a yoke, and a magnetic gap formed between the magnet and the yoke, two voice coil bodies having one axial end connected to the back side of the diaphragm and the other axial end inserted into the magnetic gap, causing the diaphragm to vibrate by moving axially within the magnetic gap relative to the magnet and the yoke, and a frame section supporting the yoke and diaphragm of the two magnetic circuit sections. The two magnetic circuit sections are positioned such that the magnetic field of one magnetic circuit section influences the magnetic field of the other magnetic circuit section. The magnetization directions of the magnets in the two magnetic circuit sections are opposite to each other. The directions of the currents flowing through the two voice coil bodies are opposite to each other as viewed from the diaphragm (first configuration).

[0009] In the above configuration, since the magnetization directions of the two magnets are opposite to each other, interference between the magnetic fluxes of the two magnetic circuit sections can be prevented, while a magnetic flux loop can be formed by the magnetic flux of one magnetic circuit section and the magnetic flux of the other magnetic circuit section. Therefore, the magnetic flux efficiency can be improved even if the distance between the yoke sections of the two magnetic circuit sections is short.

[0010] Furthermore, since the currents flowing through the two voice coil bodies are in opposite directions relative to the diaphragm, the voice coil bodies move in the same direction. This provides a configuration in which two magnetic circuit sections can efficiently drive one diaphragm.

[0011] Therefore, in a speaker that drives a single diaphragm with two magnetic circuit sections, it is possible to provide a compact configuration that can efficiently drive the diaphragm.

[0012] In the first configuration described above, the shortest distance between the two yoke portions in the direction of alignment of the magnets in the two magnetic circuit portions is smaller than the length of each magnet in the two magnetic circuit portions in the direction of alignment (second configuration).

[0013] This results in a configuration in which the magnetic flux from one of the two magnetic circuit sections is guided to the other magnetic circuit section, and the magnetic flux from the other magnetic circuit section is guided to the first magnetic circuit section. Thus, a configuration can be obtained in which the leakage magnetic flux from one magnetic circuit section can be easily captured by the other magnetic circuit section, and the leakage magnetic flux from the other magnetic circuit section can be easily captured by the first magnetic circuit section.

[0014] In the first or second configuration described above, the yoke portion each comprises a bottomed cylindrical yoke body portion that opens toward the diaphragm and a flange portion located at the open end of the yoke body portion and extending outward when viewed in the axial direction (third configuration).

[0015] In a configuration where the magnetic fields of two magnetic circuits influence each other, if the yoke portions of two magnetic circuit sections come into contact with each other, a large contact area between the yoke portions can disrupt the magnetic flux distribution in each magnetic circuit section, potentially reducing magnetic flux efficiency.

[0016] In contrast, the above-described configuration allows the flange portions to be in contact with each other, while the yoke body portions to be kept separate. This prevents the contact area between the yoke portions from becoming too large. Consequently, it is possible to prevent disturbances in the magnetic flux distribution in each magnetic circuit portion. Therefore, it is possible to suppress a decrease in the magnetic flux efficiency in each magnetic circuit portion.

[0017] In the third configuration described above, the frame portion supports the portion of the outer circumferential surface of the yoke body portion of the two magnetic circuit portions that faces each other in the direction of alignment, and supports the portion of the flange portion of the two magnetic circuit portions that is adjacent in the direction of alignment, in the axial direction (fourth configuration).

[0018] When two magnetic circuit sections are positioned such that the magnetic field of one section influences the magnetic field of the other, the magnets in the two magnetic circuit sections attract each other. Therefore, it is difficult to fix the two yoke sections in their predetermined positions.

[0019] In contrast, in the above-described configuration, the frame supports the two yoke body portions so as to be separated in the direction of their alignment, while supporting the flange portions of the yoke portions in the axial direction. This makes it possible to easily fix the two yoke portions in predetermined positions in the direction of their alignment and in the axial direction.

[0020] Therefore, in a speaker having two magnetic circuit sections, it is possible to provide a configuration that allows the two magnets to be easily fixed in close proximity to each other. [Effects of the Invention]

[0021] The speaker of the present invention has two magnetic circuit sections positioned such that the magnetic field of one magnetic circuit section influences the magnetic field of the other magnetic circuit section. The magnetization directions of the magnets in the two magnetic circuit sections are opposite to each other, and the directions of the currents flowing through the coils of the two voice coil bodies are opposite to each other as viewed from the diaphragm.

[0022] This prevents interference between the magnetic fluxes of the two magnetic circuit sections while forming a magnetic flux loop between the two magnetic circuit sections. Therefore, magnetic flux efficiency can be improved even when the distance between the yoke sections of the two magnetic circuit sections is short. Thus, in a speaker that drives a single diaphragm with two magnetic circuit sections, a compact configuration that can efficiently drive the diaphragm can be provided.

Brief Description of the Drawings

[0023] [Figure 1] FIG. 1 is a perspective view showing an example of the schematic configuration of a speaker. [Figure 2] FIG. 2 is an exploded perspective view of the speaker. [Figure 3] FIG. 3 is a sectional view taken along line III-III of FIG. 1. [Figure 4] FIG. 4 is a diagram schematically showing the flow of magnetic flux in two magnetic circuit portions. [Figure 5] FIG. 5 is a plan view of two magnetic circuit portions and two voice coil bodies as seen from the diaphragm.

Embodiments of the Invention

[0028] Speaker 1 includes a diaphragm 2, two magnetic circuit sections 3, 3, two voice coil bodies 4, 4, a frame section 5, an edge section 6, and a terminal plate 7. In speaker 1, the distance between the yoke sections 31, 31 of the two magnetic circuit sections 3, 3 is small. In this specification, "the distance between the yoke sections 31, 31 is small" means that the shortest distance between the yoke sections 31, 31 in the direction in which the magnets 32, 32 located within each yoke section 31 are aligned is smaller than the length of the magnets 32, 32 in that direction.

[0029] The diaphragm 2 is a component that converts vibrations into sound waves. The diaphragm 2 is made of, for example, synthetic resin, honeycomb metal, or the like. In this embodiment, the diaphragm 2 is rectangular in shape when viewed in the thickness direction.

[0030] Two voice coils 4, 4 are connected to the back surface of the diaphragm 2. The two voice coils 4, 4 move axially due to the magnetic field of the magnetic circuit 3. The diaphragm 2 vibrates axially due to the axial movement of the two voice coils 4, 4.

[0031] An edge portion 6 is connected to the outer circumference of the diaphragm 2. The diaphragm 2 is attached to the frame portion 5 via the edge portion 6. In other words, the diaphragm 2 is supported by the frame portion 5.

[0032] As shown in Figures 2 and 3, the two magnetic circuit sections 3,3 are located on the back side of the diaphragm 2. The two magnetic circuit sections 3,3 form independent magnetic fields, each moving one voice coil body 4,4 in the axial direction. The two magnetic circuit sections 3,3 have the same configuration except that the magnetization directions of the magnets 32 are opposite to each other. Therefore, the configuration of one magnetic circuit section 3 will be described below. The configurations of the two magnetic circuit sections 3,3 and their magnetic fields will be described later.

[0033] The magnetic circuit section 3 includes a yoke section 31, a magnet 32, a plate 33, and a magnetic gap G.

[0034] The yoke portion 31 is made of a magnetic material. Together with the plate 33, the yoke portion 31 forms a magnetic path for the magnetic flux generated by the magnet 32. The yoke portion 31 is located on the back side of the diaphragm 2 and is supported by the frame portion 5. Details of the support structure of the yoke portion 31 by the frame portion 5 will be described later.

[0035] In this embodiment, the yoke portion 31 has a bottomed cylindrical yoke body portion 311 that opens toward the diaphragm 2, and a flange portion 312 located at the open end of the yoke body portion 311 that expands outward when viewed in the axial direction.

[0036] Within the yoke body 311, the magnet 32 ​​and the plate 33 are positioned in this order toward one axial direction. The other end face of the magnet 32 ​​is in contact with the bottom surface of the yoke body 311. The yoke 31 is magnetized to have the same polarity as the end face of the magnet 32 ​​with which it is in contact.

[0037] The magnet 32 ​​has a north pole on one or the other side in the axial direction and a south pole on the opposite side. The magnet 32 ​​can be a ferrite magnet, neodymium magnet, samarium cobalt magnet, alnico magnet, etc. However, the type of magnet 32 ​​is not particularly limited.

[0038] The axial length of the magnet 32 ​​is shorter than the depth of the yoke body 311. Therefore, when positioned within the yoke body 311, one axial side of the magnet 32 ​​is located on the other axial side of the opening end of the yoke body 311. The depth of the yoke body 311 is the axial length from the axial opening end face of the yoke body 311 to the bottom surface of the yoke body 311. A plate 33 is stacked on one axial end face of the magnet 32.

[0039] A gap is formed around the entire circumference between the outer circumference of the magnet 32 ​​and the inner circumference of the yoke body 311.

[0040] The plate 33 is made of a magnetic material. Together with the yoke portion 31, the plate 33 forms a magnetic path for the magnetic flux generated by the magnet 32.

[0041] The plate 33 is plate-shaped and is stacked on one side of the magnet 32 ​​in the axial direction. The axial surface of the plate 33 and the axial end face of the yoke body 311 are at the same height in the axial direction. The plate 33 is magnetized to have the same polarity as the end face of the magnet 32 ​​it is in contact with. That is, the plate 33 has the opposite polarity to the yoke 31.

[0042] Plate 33 has a shape similar to one end face in the axial direction of magnet 32 ​​when viewed in the thickness direction. Therefore, a gap is formed around the entire circumference between the outer surface of plate 33 and the inner surface of yoke body 311. This gap constitutes a magnetic gap G. The voice coil body 4 is inserted into the magnetic gap G.

[0043] In the magnetic circuit section 3 configured as described above, a magnetic circuit is formed by the magnet 32, the yoke section 31, and the plate 33. The magnetic flux flowing through the magnetic circuit passes through the magnetic gap G. That is, the magnetic flux flowing through the magnetic circuit passes through the voice coil body 4 inserted into the magnetic gap G. As a result, the voice coil body 4 moves in the axial direction.

[0044] As shown in Figure 2, in this embodiment, the yoke body 311 is a bottomed cylindrical shape, the magnet 32 ​​is cylindrical, and the plate 33 is disc-shaped. However, the yoke body and magnet only need to be shaped such that a predetermined gap is formed around the entire circumference between the inner surface of the yoke body and the outer surface of the magnet. The plate only needs to be shaped similarly to one end of the magnet in the axial direction. For example, the yoke body, magnet and plate may be elliptical, rectangular, or the like when viewed in the axial direction.

[0045] The two voice coil bodies 4,4 vibrate the diaphragm 2. The two voice coil bodies 4,4 are each cylindrical and extend in the axial direction. Each voice coil body 4 has a cylindrical bobbin and a coil formed by winding a wire around the bobbin. One end of the voice coil body 4 in the axial direction is connected to the back surface of the diaphragm 2. The other end of the voice coil body 4 in the axial direction is inserted into the magnetic gap G so as to be movable in the axial direction relative to the yoke portion 31 and the magnet 32.

[0046] The lead wires 41 of the conductors forming the voice coil body 4 are connected in parallel to the terminal plate 7. A sound source (not shown) is connected to the terminal plate 7. An electrical signal from the sound source is sent to the voice coil body 4 via the terminal plate 7. This electrical signal flows through the voice coil body as an electric current. The voice coil body 4 moves axially within the magnetic gap G due to the magnetic field of the magnetic circuit section 3. This causes the diaphragm 2 to vibrate.

[0047] The frame section 5 supports the two yoke sections 31 of the two magnetic circuit sections 3, the diaphragm 2, and the terminal plate 7. As shown in Figures 2 and 3, the frame section 5 has a first frame section 51 located on the other side in the axial direction and a second frame section 52 located on one side in the axial direction.

[0048] The frame portion 5 is rectangular in shape, with a length in one direction greater than the length in the other when viewed in the axial direction. The frame portion 5 is sized to support a maximum of one magnetic circuit portion 3 in its short direction and a maximum of two magnetic circuit portions 3 in its longitudinal direction. That is, the length of the frame portion 5 in the short direction is less than twice the maximum length of the yoke portion 31 in the short direction. The length of the frame portion 5 in the longitudinal direction is less than three times the maximum length of the yoke portion 31 in the longitudinal direction.

[0049] The first frame portion 51 is made of a non-magnetic material. The first frame portion 51 has a bottom wall 511 located at the other end in the axial direction and a side wall 512 extending axially from the outer circumference of the bottom wall 511. That is, the first frame portion 51 has a housing space inside that accommodates two magnetic circuit portions 3, 3.

[0050] The bottom wall 511 of the first frame section 51 is provided with two through holes 51a, 51a. As shown in Figure 3, the yoke section 31 of the magnetic circuit section 3 is inserted into and fixed into each of the two through holes 51a, 51a. A terminal plate 7 is attached to the other axial side of the first frame section 51.

[0051] More specifically, as shown in Figure 3, the two yoke portions 31, 31 are inserted into the two through holes 51a, 51a, with the portions on the other axial side of the flange portion 312 of the yoke body portion 311 being inserted into each of them. In this embodiment, when inserted into the through hole 51a, the outer circumferential surface of the yoke body portion 311 is in contact with the inner circumferential surface of the through hole 51a. In addition, the flange portion 312 is in contact with the portion of the bottom wall 511 that is located around the through hole 51a when viewed in the axial direction.

[0052] The second frame portion 52 is located on one side in the axial direction relative to the first frame portion 51. The second frame portion 52 extends in an annular shape along the end face of the first frame portion 51 on the side of the opening 51b. That is, the second frame portion 52 is rectangular in shape and has a rectangular opening 52a. The diaphragm 2 is attached to the second frame portion 52 via the edge portion 6 so that it is located inside the opening 52a when viewed in the axial direction.

[0053] The edge portion 6 is located between the inner circumference of the second frame portion 52 and the outer circumference of the diaphragm 2, and supports the diaphragm 2 so that it can be displaced axially relative to the frame portion 5. The edge portion 6 is made of a flexible material, such as foamed rubber. The edge portion 6 functions to return the diaphragm 2, which has been displaced axially by the voice coil body 4, back to its original position.

[0054] (Configuration and magnetic field of the two magnetic circuit sections) Next, with reference to Figures 4 and 5, the magnetic field formed by the two magnetic circuit sections 3 of speaker 1 will be explained. Figure 4 is a schematic diagram showing the flow of magnetic flux in the two magnetic circuit sections 3, 3 of speaker 1. Figure 5 is a plan view of the two magnetic circuit sections 3, 3 and the two voice coil bodies 4, 4 as seen from the diaphragm 2. In Figure 4, the flow of magnetic flux is indicated by dashed arrows. Also, the direction in which the voice coil body 4 moves when current flows is indicated by white arrows. In Figure 5, the direction of the current flowing through the coil is indicated by solid arrows.

[0055] As described above, the two magnetic circuit sections 3,3 of speaker 1 form independent magnetic fields. That is, in speaker 1, the first magnetic circuit section 3a, which is one of the two magnetic circuit sections 3,3, forms one magnetic field, and the other, the second magnetic circuit section 3b, forms another magnetic field. Also, in speaker 1, the distance between the yoke sections 31,31 of the two magnetic circuit sections 3,3 is close. Therefore, in speaker 1, the magnetic field of the first magnetic circuit section 3a influences the magnetic field of the second magnetic circuit section 3b.

[0056] In speaker 1, the magnetization direction of the magnet 32 ​​in the first magnetic circuit section 3a and the magnetization direction of the magnet 32 ​​in the second magnetic circuit section 3b are opposite to each other. For example, the magnet 32 ​​in the first magnetic circuit section 3a has a north pole on one side in the axial direction and a south pole on the other side. The magnet 32 ​​in the second magnetic circuit section 3b has a south pole on one side in the axial direction and a north pole on the other side.

[0057] Therefore, in speaker 1, the magnetic flux of the first magnetic circuit section 3a and the magnetic flux of the second magnetic circuit section 3b do not interfere with each other. That is, the magnetic flux of the first magnetic circuit section 3a can flow toward the second magnetic circuit section 3b. Consequently, leakage flux in the first magnetic circuit section 3a is reduced. Also, the magnetic flux of the second magnetic circuit section 3b can flow toward the first magnetic circuit section 3a. Consequently, leakage flux in the second magnetic circuit section 3b is reduced.

[0058] Furthermore, by arranging the two magnets 32 in this manner, the leakage flux generated in the first magnetic circuit section 3a can be guided to the second magnetic circuit section 3b, and the leakage flux generated in the second magnetic circuit section 3b can be guided to the first magnetic circuit section 3a. Therefore, the overall amount of leakage flux can be reduced. Consequently, the effective magnetic flux amount increases. Therefore, a compact configuration with improved magnetic flux efficiency can be realized.

[0059] As shown in Figure 5, in speaker 1, the directions of the currents flowing through the two voice coil bodies 4, 4 are opposite to each other when viewed from the diaphragm 2. For example, the direction of the current flowing through the first voice coil body 4a, which is located in the magnetic gap G of the first magnetic circuit section 3a, is clockwise when viewed from the diaphragm 2. The direction of the current flowing through the second voice coil body 4b, which is located in the magnetic gap G of the second magnetic circuit section 3b, is counterclockwise when viewed from the diaphragm 2.

[0060] As a result, when current flows through the first voice coil 4a, the first voice coil 4a moves to one side in the axial direction. When current flows through the second voice coil 4b, the second voice coil 4b moves to one side in the axial direction. In other words, the first voice coil 4a and the second voice coil 4b are driven in the same direction. Therefore, the two magnetic circuit sections 3,3 can efficiently drive one diaphragm 2.

[0061] Therefore, in a speaker 1 in which one diaphragm 2 is driven by two magnetic circuit sections 3,3, a compact configuration that can efficiently drive the diaphragm 2 can be provided.

[0062] (Support structure for the two yoke sections by the frame section) Next, with reference to Figures 2 and 3, the support structure of the two yoke sections 31, 31 by the frame section 5 will be described.

[0063] As described above, the first frame portion 51 has two through holes 51a, 51a in the bottom wall 511 into which two yoke body portions 311, 311 are inserted, respectively. The other axial side of the yoke body portion 311 is inserted into each through hole 51a. The two flange portions 312, 312 are located on one axial side of the two through holes 51a, 51a. The outer circumferential surface of the yoke body portion 311 is in contact with the inner circumferential surface of each through hole 51a. The other axial side of the two flange portions 312, 312 is in contact with one axial side of the bottom wall 511 of the first frame portion 51.

[0064] As a result, the two yoke sections 31, 31 are positioned in predetermined locations relative to the first frame section 51 in the direction of alignment, width, and axial direction.

[0065] In this embodiment, with the two yoke portions 31, 31 inserted into the two through holes 51a, 51a respectively, the flange portions 312, 312 of the two yoke portions 31, 31 are in contact with each other. Therefore, the two yoke body portions 311, 311 are separated from each other.

[0066] In a configuration where the magnetic fields of two magnetic circuits influence each other, if the yoke portions of two magnetic circuit sections come into contact with each other, a large contact area between the yoke portions can disrupt the magnetic flux distribution in each magnetic circuit section, potentially reducing magnetic flux efficiency.

[0067] In contrast, in the above configuration, the flange portions 312, 312 are in contact with each other, while the yoke body portions 311, 311 are not in contact with each other. This prevents the contact area between the yoke portions 31, 31 from becoming too large. Therefore, it is possible to prevent disturbance in the magnetic flux distribution in each of the two magnetic circuit portions 3, 3. Thus, it is possible to suppress a decrease in the magnetic flux efficiency in each magnetic circuit portion 3.

[0068] Furthermore, a portion of the bottom wall 511 of the first frame portion 51 is located between the portions of the two yoke body portions 311, 311 that face each other in the direction in which the two yoke portions 31, 31 are aligned. Also, a portion of the bottom wall 511 of the first frame portion 51 is in axial contact with portions of the two flange portions 312, 312 that are adjacent in the direction in which they are aligned.

[0069] When the magnets 32,32 of the two magnetic circuit sections 3,3, as in speaker 1, are located close together and have opposite magnetization directions, the two magnets 32,32 attract each other. Therefore, it is difficult to fix the two yoke sections 31,31 in their predetermined positions.

[0070] In contrast, the aforementioned portion of the bottom wall 511 of the first frame portion 51 supports the two yoke body portions 311, 311 so as to be separated in the direction of alignment, while supporting the flange portion 312 of the yoke portion 31 in the axial direction. This makes it possible to easily fix the two yoke portions 31, 31 in predetermined positions in their alignment direction and axial direction.

[0071] Therefore, in a speaker 1 in which one diaphragm 2 is driven by two magnetic circuit sections 3,3, a compact and easily fixable configuration can be provided.

[0072] The exemplary speaker 1 described above comprises a diaphragm 2, two magnetic circuit sections 3, 3 located on the back side of the diaphragm 2 and each having a magnet 32, a yoke section 31, and a magnetic gap G formed between the magnet 32 ​​and the yoke section 31, two voice coil bodies 4, 4, each having one end in the axial direction connected to the back side of the diaphragm 2 and the other end in the axial direction inserted into the magnetic gap G, causing the diaphragm 2 to vibrate by moving axially relative to the magnet 32 ​​and the yoke section 31 within the magnetic gap G, and a frame section 5 that supports the yoke sections 31 of the two magnetic circuit sections 3, 3 and the diaphragm 2. The two magnetic circuit sections 3, 3 are positioned such that the magnetic field of one magnetic circuit section 3 influences the magnetic field of the other magnetic circuit section 3. The magnetization directions of the magnets 32 in the two magnetic circuit sections 3, 3 are opposite to each other. The directions of the currents flowing through the two voice coil bodies 4, 4 are opposite to each other as viewed from the diaphragm 2.

[0073] In a speaker with two magnetic circuit sections, the amount of magnetic flux that drives the diaphragm is greater than in a speaker with one magnetic circuit section, thus improving the efficiency of driving the diaphragm. On the other hand, if the magnetization direction of the magnets in the two magnetic circuit sections is the same, and the distance between the yoke sections of the two magnetic circuit sections is close and their magnetic fields influence each other, the magnetic fluxes of the two magnetic circuit sections interfere, increasing the leakage flux and reducing the magnetic flux efficiency.

[0074] In the above configuration, since the magnetization directions of the two magnets 32, 32 are opposite to each other, interference between the magnetic fluxes of the two magnetic circuit sections 3, 3 can be prevented, while a magnetic flux loop can be formed by the magnetic flux of one magnetic circuit section 3 and the magnetic flux of the other magnetic circuit section 3. Therefore, even if the distance between the yoke sections 31, 31 of the two magnetic circuit sections 3, 3 is short, the magnetic flux efficiency can be improved.

[0075] Furthermore, since the direction of the current flowing through the two voice coil bodies 4,4 is opposite to that of the diaphragm 2, the voice coil bodies 4,4 move in the same direction. This provides a configuration in which the two magnetic circuit sections 3,3 can efficiently drive one diaphragm 2.

[0076] Therefore, in a speaker 1 in which one diaphragm 2 is driven by two magnetic circuit sections 3,3, a compact configuration that can efficiently drive the diaphragm 2 can be provided.

[0077] Furthermore, in this embodiment, the yoke portion 31 each has a bottomed cylindrical yoke body portion 311 that opens toward the diaphragm 2, and a flange portion 312 located at the opening end of the yoke body portion 311 that expands outward when viewed in the axial direction.

[0078] In a configuration where the magnetic fields of two magnetic circuits influence each other, if the yoke portions of two magnetic circuit sections come into contact with each other, a large contact area between the yoke portions can disrupt the magnetic flux distribution in each magnetic circuit section, potentially reducing magnetic flux efficiency.

[0079] In contrast, the above-described configuration allows the flange portions 312, 312 to be in contact with each other, while the yoke body portions 311, 311 are not in contact with each other. This prevents the contact area between the yoke portions 31, 31 from becoming too large. Therefore, it is possible to prevent disturbance in the magnetic flux distribution in each magnetic circuit portion 3. Thus, it is possible to suppress a decrease in the magnetic flux efficiency in each magnetic circuit portion 3.

[0080] Furthermore, in this embodiment, the frame portion 5 supports the portions of the outer circumferential surface of the yoke body portion 311 of the two magnetic circuit portions 3, 3 that face each other in the alignment direction, and supports the portions of the flange portion 312 of the two magnetic circuit portions 3, 3 that are adjacent in the alignment direction, in the axial direction.

[0081] When two magnetic circuit sections 3,3 are positioned such that the magnetic field of one magnetic circuit section 3 affects the magnetic field of the other magnetic circuit section 3, the magnets 32,32 of the two magnetic circuit sections 3,3 attract each other. Therefore, it is difficult to fix the two yoke sections 31,31 in their predetermined positions. In contrast, in the above configuration, the frame section 5 supports the two yoke body sections 311,311 so as to be separated in the direction of alignment, while supporting the flange section 312 of the yoke section 31 in the axial direction. As a result, the two yoke sections 31,31 can be easily fixed in their predetermined positions in both the direction of alignment and the axial direction.

[0082] Therefore, in a speaker 1 having two magnetic circuit sections 3, 3, it is possible to provide a configuration in which the two magnets 32, 32 can be easily fixed in close proximity to each other.

[0083] (Other embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0084] In the above embodiment, the flange portions 312, 312 of the yoke portions 31 of the two magnetic circuit portions 3, 3 are in contact with each other. That is, the two yoke portions 31, 31 are in contact with each other. However, the two yoke portions only need to be positioned such that the magnetic field of one of the two magnetic circuit portions influences the magnetic field of the other. For example, the shortest distance between the two yoke portions in the direction of alignment of the magnets in the two magnetic circuit portions may be smaller than the length of each magnet in the direction of alignment of the magnets in the two magnetic circuit portions.

[0085] This results in a configuration in which the magnetic flux from one of the two magnetic circuit sections is guided to the other magnetic circuit section, and the magnetic flux from the other magnetic circuit section is guided to the first magnetic circuit section. Thus, a configuration can be obtained in which the leakage magnetic flux from one magnetic circuit section can be easily captured by the other magnetic circuit section, and the leakage magnetic flux from the other magnetic circuit section can be easily captured by the first magnetic circuit section.

[0086] In the above embodiment, the flange portions 312, 312 of the yoke portions 31 of the two magnetic circuit portions 3, 3 are in contact with each other. However, the flange portions do not have to be in contact with each other. There may be a small gap between the flange portions at the point where the two flange portions are closest to each other. For example, there may be a gap between the flange portions that is smaller than the thickness of the yoke body.

[0087] In the above embodiment, the magnetic circuit section 3 has a plate 33. However, the magnetic circuit section does not have to have a plate. That is, a plate does not have to be stacked on one side in the axial direction of the magnet. In this case, it is preferable that the length of the magnet in the axial direction is equal to the depth of the yoke body. However, in order to reduce leakage flux and improve magnetic efficiency, it is preferable that a plate is located on one side in the axial direction of the magnet.

[0088] In the above embodiment, the yoke portion 31 has a flange portion 312. However, the yoke portion does not necessarily have to have a flange portion. However, it is preferable for the yoke portion to have a flange portion in order to position the yoke portion relative to the frame portion.

[0089] In the above embodiment, the two yoke portions 31, 31 of the two magnetic circuit portions 3, 3 are positioned in predetermined positions relative to the frame portion 5 in the alignment direction, width direction, and axial direction by being inserted into the two through holes 51a, 51a of the first frame portion 51. However, the two yoke portions may be positioned in predetermined positions relative to the frame portion by other means. For example, the two yoke portions may be positioned in predetermined positions by being supported by a plurality of projections protruding from the bottom wall of the first frame portion to one side in the axial direction.

[0090] Furthermore, it is preferable that the frame portion has a portion that supports the portions of the outer circumferential surface of the yoke body portions of the two magnetic circuit portions that face each other in the direction of alignment. Also, it is preferable that the frame portion has a portion that supports the portions of the flange portions of the two magnetic circuit portions that are adjacent in the direction of alignment in the axial direction. [Industrial applicability]

[0091] The present invention can be used in a speaker that vibrates a single diaphragm using two voice coil bodies arranged in relation to two magnetic circuit sections. [Explanation of symbols]

[0092] 1 speaker 2 diaphragm 3. Magnetic circuit section 3a First magnetic circuit section 3b Second Magnetic Circuit Section 4 Voice coil body 4a First voice coil 4b Second voice coil 5. Frame section 6. Edge section 7 Terminal board 31 York section 32 magnets 33 plates 41 Leader wire 51 First frame section 51a Through hole 51b aperture 52 Second frame section 52a aperture 311 Yoke main body 312 Flange section 511 Bottom wall 512 Side wall G magnetic gap

Claims

1. The diaphragm and Each of the two magnetic circuit sections has a magnet, a yoke, and a magnetic gap formed between the magnet and the yoke, and is located on the back side of the diaphragm. Two voice coil bodies, one end in the axial direction of each voice coil body connected to the back surface of the diaphragm and the other end in the axial direction of each voice coil body inserted into the magnetic gap, move in the axial direction relative to the magnet and the yoke within the magnetic gap, thereby vibrating the diaphragm; The yoke portion and the frame portion supporting the diaphragm of the two magnetic circuit sections, A speaker having, The two magnetic circuit sections are positioned such that the magnetic field of one magnetic circuit section influences the magnetic field of the other magnetic circuit section. The magnetization directions of the magnets in the two magnetic circuit sections are opposite to each other. The directions of the currents flowing through the two voice coil bodies are opposite to each other when viewed from the diaphragm. Speaker.

2. In the speaker according to claim 1, The shortest distance between the two yoke portions in the direction of alignment of the magnets in the two magnetic circuit portions is smaller than the length of each magnet in the direction of alignment in the two magnetic circuit portions. Speaker.

3. In the speaker according to claim 1 or claim 2, The aforementioned yoke sections are, A bottomed cylindrical yoke body portion that opens toward the diaphragm, A flange portion located at the open end of the yoke body and extending outward when viewed in the axial direction, Having, Speaker.

4. In the speaker described in claim 3, The frame portion supports the portions of the outer circumferential surface of the yoke body portion of the two magnetic circuit portions that face each other in the direction of alignment, and supports the portions of the flange portion of the two magnetic circuit portions that are adjacent in the direction of alignment, in the axial direction. Speaker.

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