JP3008768U - Magnetic shield type speaker - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a magnetic-shield type speaker suitable for televisions and audiovisuals, which has a small leakage flux 7a even in a speaker having an open loop magnetic circuit due to a repulsive magnetic field. A repulsive magnetic field type speaker in which a repulsive magnetic field is formed by arranging two magnets 1 and 2 in a magnetic direction that repels each other, and a voice coil wound around a voice coil bobbin is arranged in the repulsive magnetic field. The repulsive magnet 6 is arranged so as to oppose the magnet 2 in the repulsive magnetic direction, and the outer yoke 5 made of a magnetic material is provided on the back surface of the repulsive magnet 6.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thin and lightweight speaker that utilizes a so-called repulsive magnetic field.

[0002]

[Prior art]

 Conventionally, as a thin and lightweight speaker, which is formed by sandwiching a magnetic or non-magnetic spacer and two thin disk-shaped magnets on opposite sides of the same polarity so as to face each other, for example, the present application There are Japanese Patent Application No. 5-39321, Japanese Patent Application No. 5-39320, and the like by the same applicant, and their respective configurations are shown in FIGS. 4 and 5.

The speaker configured as shown in FIG. 4 forms a repulsive magnetic field 24 by arranging two magnets 21 and 22 in a magnetic direction that repels each other, and the repulsive magnetic field 24 is formed in the center of the outer periphery of the voice coil bobbin 25. A voice coil 26 wound around the voice coil 26 is arranged, a diaphragm 28 is connected to the central portion of the outer periphery of the voice coil 26, and both end portions of the outer periphery of the voice coil bobbin 25 are arranged at intervals. The support system of the voice coil 26, which is connected to the two dampers 29 and 30, is formed symmetrically with respect to the central axis Y-Y 'orthogonal to the axial direction X-X' of the voice coil 26. is there.

The speaker configured as shown in FIG. 5 forms a repulsive magnetic field 45 by arranging two magnets 43, 44 in a magnetic direction that repels each other in the central portion of the frame 41, and in the repulsive magnetic field 45, A voice coil 46 wound around the central portion of the outer periphery of the voice coil bobbin 47 is arranged, and the central portion of the outer periphery of the voice coil 46 is supported by the frame 41 via a damper 52. A cone-shaped diaphragm 48 is provided between the central portion and the frame 41.

[0005]

[Problems to be solved by the device]

 Although the speaker having such a structure is effective in reducing the thickness and weight, as shown in FIG. 3, since it is an open-loop magnetic circuit due to a repulsive magnetic field, there are many leakage fluxes (leakage magnetic flux) 7a, especially in a frame. This is noticeable on the back side of. Here, FIG. 3 shows a magnetic circuit of the speaker of FIGS. 4 and 5, in which 1 and 2 are magnets, 3 is a frame of a non-magnetic material, 4 is a plate as a spacer, 7 is a magnetic field line, 7a is a leakage flux.

The leakage flux 7a on the back surface of the frame is, for example, 70 × 10 ⁻⁴ T leakage flux 7a in the above-mentioned conventional speaker, which cannot be used for televisions and audiovisuals.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic shield that is suitable for a television or an audiovisual device having a small leakage flux 7a even in a speaker having an open loop magnetic circuit due to a repulsive magnetic field. Type speaker.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention forms a repulsive magnetic field by arranging two magnets 1 and 2 in a magnetic direction that repels each other, and a voice coil wound around a voice coil bobbin is arranged in the repulsive magnetic field. In the repulsive magnetic field type speaker, the repulsive magnet 6 is arranged so as to oppose one of the magnets 2 in the repulsive magnetic direction, and the outer yoke 5 made of a magnetic material is provided on the back surface of the repulsive magnet 6.

Further, the frame 3 has the function of the outer yoke 5.

Alternatively, in the above two inventions, a gap is provided between the one magnet 2 and the repulsion magnet 6.

A repulsive magnetic field is formed by arranging the two magnets 1 and 2 in a magnetic direction that repels each other, and a voice coil wound around the central portion of the outer periphery of the voice coil bobbin is formed by the repulsive magnetic field. In the repulsive magnetic field type speaker of the arranged non-magnetic body frame 3, the repulsive magnet 6 is arranged in the repulsive magnetic direction so as to oppose the one magnet 2, and a gap is provided between the one magnet 2 and the repulsive magnet 6. The outer yoke 5 is made of a flat plate or a tray-shaped magnetic material having an outer peripheral end curved upwardly on the back surface of the repulsive magnet 6.

[0012]

[Action]

 By arranging the two magnets 1 and 2 in a magnetic direction that repels each other to form a repulsive magnetic field, one magnet 2 of the speaker is arranged in the magnetic direction in which the repulsive magnet 6 repels. The magnetic field lines 7 leaking from the magnet 2 toward the rear surface of the frame 3 are flattened due to the influence of the magnetic circuit of the repulsion magnet 6 and the outer yoke 5, and the leakage flux 7a in the rear surface direction of the frame is reduced.

If the frame 3 is made of a magnetic material, the frame 3 can be replaced with the outer yoke 5 without providing the outer yoke 5.

Further, by providing a gap between the one magnet 2 and the repulsion magnet 6 and adjusting this gap, even if the repulsion magnet 6 is small, the leakage flux 7a in the rear surface direction of the frame can be reduced.

In addition, in a speaker in which a repulsive magnetic field is formed by arranging two magnets 1 and 2 in a magnetic direction that repels each other, a magnetic direction that repels a repulsive magnet 6 to oppose one magnet 2. And a gap is provided between one of the magnets 2 and the repulsion magnet 6, and a flat plate or an outer yoke 5 made of a tray-shaped magnetic material with an outer peripheral end curved upward is provided on the back surface of the repulsion magnet 6. Thus, the magnetic flux from the repulsion magnet 6 to the outer yoke 5 can more efficiently reduce the leakage flux 7a in the rear surface direction of the frame.

[0016]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a vertical half sectional view showing a typical embodiment of the present invention. In the figure, magnets 1 and 2 are arranged in front of and behind a plate 4 made of a magnetic material in the center of a frame 3 made of a non-magnetic material. The magnets 1 and 2 are formed in a ring shape or a disk shape and are magnetized in the thickness direction. Moreover, anisotropic magnets (neodymium magnet) are preferably used for these magnets 1 and 2. The opposing surfaces of the magnets 1 and 2 with the plate 4 in between are magnetized in the magnetic directions repulsive to each other, that is, N pole-N pole or S pole-S pole, and a repulsive magnetic field is formed. ing. Although the plate 4 is formed of a magnetic material such as SS41, it may be formed of a non-magnetic material, or only the gap may be formed without interposing the plate 4.

A voice coil (not shown) is installed in the repulsive magnetic field. The voice coil is formed by being wound around the center of the outer circumference of a voice coil bobbin provided so as to be vibrable on the outer circumferences of the magnets 1 and 2.

One end of one of the magnets 1 and 2 is supported at its lower end by the upper edge of a non-magnetic frame 3 whose center portion is curved and protrudes upward. It is curved downward near the outer peripheral edge to form a disk-shaped bottom with a predetermined depth, and the outer peripheral portion is curved upward to support a damper and a diaphragm (not shown).

A repulsive magnet 6 is arranged in the lower part of the central portion of the frame 3 which is curved and protrudes upward in a magnetic repulsive direction so as to oppose one of the magnets 2. That is, the magnets 2 are arranged so as to be S pole-S pole or N pole-N pole with respect to one magnet 2. The repulsive magnet 6 is also formed in a ring shape or a disk shape and is magnetized in the thickness direction. Further, the material thereof is preferably the same as that of the magnets 1 and 2.

The lower portion corresponding to the back surface of the repulsion magnet 6 is supported by an outer yoke 5 made of a disc-shaped tray with its outer peripheral end curving upward and projecting, for example, SS41. The magnetic field lines 7 leaking toward the back surface of the frame 3 from one of the magnets 2 are pushed by the repulsive magnetic field lines 7a from the one magnet 2 due to the repulsive magnetic field lines 7a extending from the above portion to the outer peripheral upper end portion of the outer yoke 5. The leakage flux 7a is reduced in shape due to the flattened shape.

In the above-described embodiment, the outer yoke 5 is a disc-shaped magnetic material having a disc-like shape with its outer peripheral end curved and protruding upward, but a disc-shaped flat plate is also provided between the outer yoke 5 and the repulsion magnet 6. It has the effect of forming a magnetic circuit and reducing the leakage flux 7a.

Further, since the repulsion magnet 6 and one of the magnets 2 have a certain distance, that is, a gap, by the frame 3 which is curved and projected upward in the central portion, the leakage flux 7a can be adjusted by adjusting the size of this gap. Can be further reduced.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a vertical half sectional view of another embodiment of the present invention.

In the figure, the point that a repulsive magnetic field is formed by sandwiching the plate 4 by the two magnets 1 and 2 is the same as in the above-described embodiment, and the description thereof is omitted. A spacer 8 made of a non-magnetic material such as a resin material is disposed below the one magnet 2 of the two magnets 1 and 2, and the repulsive magnet 6 is provided through this spacer 8 in one direction as in the above embodiment. The magnets 2 are arranged so as to oppose the magnet 2 and repel each other.

The lower portion of the repulsive magnet 6 is supported by a frame 3 made of a magnetic material, for example, SS41 or the like, the outer periphery of which is curved and protrudes upward, and this frame 3 functions as the outer yoke 5 in the above embodiment. In other words, the magnetic circuit formed by the repulsive magnet 6 and the frame 3 can suppress the magnetic flux 7 that tends to leak from the one magnet 2 toward the back surface of the frame 3 and reduce the leakage flux 7a. The frame 3 made of this magnetic material may be a flat plate as in the above embodiment.

Further, by changing the size of the spacer 8, the gap between the one magnet 2 and the repulsive magnet 6 can be adjusted, whereby the leakage flux 7a can be adjusted to the minimum.

As described above, in the above two embodiments, the size and material of the repulsive magnet 6, the setting of the gap between the one magnet 2 and the repulsive magnet 6, and the size and thickness parameters of the outer yoke 5 are set to appropriate values. By setting it, the leakage flux 7a can be reduced, and in the result of this embodiment, 2.5 × 10 ⁻⁴ T (reduction of 96.4%) can be achieved on the back surface of the outer yoke 5. This value can be used not only for EIAJ magnetic shield type speaker system grade 1, but also for TV.

[0028]

[Effect of device]

 As described above, according to the present invention, by arranging the two magnets 1 and 2 in a magnetic direction that repels each other, one magnet 2 of the speaker that forms a repulsive magnetic field, and the repulsive magnet 6 in the magnetic direction that repels. Since the arrangement is made, the leakage flux 7a can be reduced, and the magnetic shield type speaker suitable for television and audiovisual can be provided.

Furthermore, according to the present invention, since the frame 3 is made to have the function of the outer yoke 5, the outer yoke 5 becomes unnecessary when the frame 3 is made of a magnetic material, and the number of manufacturing steps is reduced. Cost reduction.

Further, since the gap is provided between the one magnet 2 and the repulsion magnet 6, the leakage flux 7a can be further reduced.

The outer yoke 5 made of a magnetic material provided on the back surface of the repulsion magnet 6 has a flat plate or a tray-like shape with the outer peripheral edge curving upward and is excellent in suppressing the leakage flux 7 a, and is easy for a conventional speaker. It can be attached to.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a magnetic field shield type speaker according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a magnetic field shield type speaker according to another embodiment of the present invention.

FIG. 3 is a view not showing a magnetic circuit of a speaker using a conventional repulsive magnetic field.

FIG. 4 is a diagram showing an example of a speaker using a conventional repulsive magnetic field.

FIG. 5 is a diagram showing another example of a conventional speaker using a repulsive magnetic field.

[Explanation of symbols]

 1 Magnet 2 Magnet 3 Frame 4 Plate 5 Outer Yoke 6 Repulsive Magnet 7 Magnetic Field Line 7a Leakage Flux 7b Repulsive Magnetic Field 8 Spacer 21, 22, 43, 44 Magnet 23, 42 Spacer 24, 45 Repulsive Magnetic Field 25, 47 Voice Coil Bobbin 26, 46 Voice Coil 28,48 Vibration plate 29,30,52 Damper 31,32,41 Frame 31a Sound hole 50 Subcone

Claims (4)

[Scope of utility model registration request] 1. A repulsive magnetic field is formed by arranging two magnets (1, 2) in a magnetic direction that repels each other,
In a repulsive magnetic field type speaker in which a voice coil wound around a voice coil bobbin is arranged in this repulsive magnetic field, a repulsive magnet (6) is arranged in a magnetic direction to repel so as to oppose one of the magnets (2). A magnetic-shield type speaker characterized in that an outer yoke (5) made of a magnetic material is provided on the back surface of (6). 2. A magnetic shield speaker according to claim 1, wherein the frame (3) has the function of an outer yoke (5). 3. The magnetic shield speaker according to claim 1, wherein a gap is provided between the one magnet (2) and the repulsion magnet (6). 4. A repulsive magnetic field is formed by arranging two magnets (1, 2) in a magnetic direction that repels each other,
In the repulsive magnetic field type speaker of the non-magnetic frame (3) in which the voice coil wound around the substantially outer periphery of the voice coil bobbin is arranged in the repulsive magnetic field, the repulsive magnet is arranged to oppose one of the magnets (2). (6) is arranged in a repulsive magnetic direction, a gap is provided between the one magnet (2) and the repulsive magnet (6), and a flat plate or an outer peripheral end is curved and protrudes upward on the back surface of the repulsive magnet (6). A magnetic-shield type speaker characterized in that an outer yoke (5) made of the tray-shaped magnetic material is provided.