JP2607796Y2 - Magnetic circuit for speaker - 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 circuit for a loudspeaker. More particularly, the present invention relates to a magnetic circuit for a loudspeaker. The present invention relates to a speaker magnetic circuit configured to be arranged and driven.

[0002]

2. Description of the Related Art Conventionally, a magnetic circuit structure of a loudspeaker generally used includes an external magnet type as shown in FIG.
4 is frequently used. In recent years, there has been a demand for weight reduction of speakers, especially for in-vehicle speakers.
In order to reduce the weight of the magnetic circuit components that occupy most of the speaker weight, for example, a high-performance magnet such as a neodymium magnet is used to cope with the weight reduction. In the drawing, 1 is a magnet, Y is a yoke, and P is a top plate, and these constitute a magnetic circuit. In addition, 5 is a frame, 7 is a diaphragm, 8 is a voice coil, and 9 is a damper. By reducing the weight of the magnetic circuit component, the strength of the frame 5 for supporting the magnetic circuit component, the diaphragm 7 and the like can be reduced and the function can be satisfied. Therefore, the reduction in the weight of the magnetic circuit component leads to a reduction in the weight of the frame 5, and the overall weight of the speaker can be reduced. The lighter the weight of the magnetic circuit component is, the more effective it is. Is required.

However, in the external magnet type magnetic circuit shown in FIG. 13, due to its structure, the magnet 1 must be larger than the outer diameter of the voice coil 8, and as shown in the drawing, the magnet 1 There is a disadvantage that the outer diameter increases, and a top plate P, a yoke Y, and the like corresponding to the outer diameter are required.
Generally, when a neodymium magnet is used, the weight can be reduced by about 60% to 70% as compared with an external magnet type magnetic circuit using a normal ferrite magnet. Because the outer diameter is large,
Further weight reduction is a difficult structure.

An inner magnet type magnetic circuit as shown in FIG. 14 does not have the disadvantage that the outer diameter of the magnet 1 is increased as described above, but it is used for a bass speaker in which the amplitude of the diaphragm 7 is large. In order to prevent the bobbin end 81 of the voice coil 8 from hitting the bottom surface TY1 of the urn yoke TY and generating an unusual noise, a sufficient stroke margin of the voice coil 8 is secured, that is, the depth of the urn yoke TY It is necessary to use a material having a larger depth, and the amount of the yoke material (iron material or the like) corresponding to the depth increases, so that the weight inevitably increases. Generally, when a neodymium magnet is used, the weight can be reduced by about 65% to 70% as compared with an inner magnet type magnetic circuit using a normal ferrite magnet, but even if a neodymium magnet is used,
Due to the large amount of yoke material, further weight reduction is difficult.

As is well known, when magnets are opposed at a predetermined interval so that the same poles face each other, repulsive magnetic flows generated from the opposed surfaces of the magnets are directed from the opposed surface to the outer peripheral portion of the magnet. Since a magnetic field (hereinafter referred to as “repulsive magnetic field”) is generated further outward from the vicinity of the outer peripheral portion, there is a magnetic circuit structure of a type in which a voice coil is arranged in the repelling magnetic field to drive the voice coil. Various types of magnetic circuit structures of this type and speakers using this magnetic circuit have been proposed (for example, Japanese Patent Application Laid-Open No. 56-34298 and Japanese Utility Model Publication No. 59-3111).
No. 0, Japanese Utility Model Laid-Open No. 59-48197, Japanese Patent Publication No. 60-327
No. 0, No. 61-128896, No. 62-10
3395, JP-A-1-98400, etc.). These are roughly classified into: (1) a magnet in which the same polarity side is simply opposed at a predetermined interval; and (2) a normal inner magnet type magnetic circuit is improved and developed, and a magnet is mounted on a top plate. (3) As shown in JP-A-1-98400,
There is a voice coil that is to be arranged in the repulsive magnetic field, and an amorphous metal tape or the like is wound around the outside of the voice coil.

[0006]

However, in the case of the above (1), the magnetic flux distribution is extremely narrow, so that a diaphragm for a generally used speaker, particularly a diaphragm for a vehicle-mounted speaker or the like, is sufficient. Since a magnetic flux cannot be obtained and it can be used only for a very special speaker, for example, a headphone or the like that requires a small amplitude, there is a disadvantage that the use range is greatly limited.

In the case of the above (2),
(A) The magnetic flux distribution with respect to the driving direction of the voice coil is not symmetrical, and the magnetic circuit has a driving force different in the amplitude direction of the diaphragm. (B) A pot yoke basically as shown in FIG. Due to the TY structure, similar to the above-described inner-magnet type magnetic circuit, there are disadvantages such as that there is a limit in reducing the weight of the speaker. In order to use the disadvantage that the magnetic flux distribution is not symmetrical and to use the leaked magnet more efficiently, the pot yoke TY
And a voice coil disposed inside the pot yoke TY (Japanese Patent Publication No. 60-3270). In this method, a voice coil is connected to connect the voice coil to the diaphragm. Since a plate is provided on the outer peripheral portion and the plate is connected to the diaphragm, a slit must be provided on a side surface of the pot yoke TY so that the plate can move up and down. Not only becomes extremely complicated, but basically, two pot yokes TY are arranged on the upper and lower sides, so that the extra stroke of the coil is reduced to the lower pot yoke TY.
It must be provided not only on the side but also on the upper pot yoke TY. Therefore, the weight of the speaker can be reduced by using the ordinary pot yoke T
More difficult than with Y.

Further, in the case of the configuration example (3), since an amorphous metal tape or the like is wrapped around the outside of the voice coil, the weight of the voice coil becomes heavy, and the efficiency is lower than that of a normal moving coil type speaker. It is natural to do.

It is an object of the present invention to provide a magnetic circuit for a speaker which solves the above-mentioned drawbacks of the conventional magnetic circuit, is suitable for reducing the weight of the magnetic circuit section and the whole speaker, and has excellent performance. .

[0010]

According to a first aspect of the present invention, there is provided a speaker magnetic circuit according to the first aspect of the present invention, wherein the outer peripheral circular magnet magnetized in the thickness direction is opposed to the same pole side. In a loudspeaker in which voice coils are arranged in a magnetic field generated by both magnets at a predetermined interval so that a center plate having a circular outer circumference made of a magnetic material is sandwiched between opposing surfaces of both magnets. The center plate is set so that the diameter of the center plate is larger than the diameter of the magnet, and the size difference is set to be 4 mm or less.

According to the second aspect of the present invention, the outer circumferential magnet magnetized in the thickness direction is arranged at a predetermined interval so that the same poles are opposed to each other, and the magnet is disposed within the magnetic field generated by both magnets. In a speaker in which a voice coil is arranged, an outer peripheral circular center plate made of a magnetic material is arranged so as to be sandwiched between opposing surfaces of both magnets, and the magnet and the center plate have a ring shape and have a substantially bottomed shape. It is held by a cylindrical holder made of non-magnetic material, and a center portion of the holder is formed with a center guide portion for inserting the center hole of the magnet and the center plate, and a lower portion of the center guide portion is formed. A mounting portion for supporting the magnet and the center plate is formed.

[0012]

In a conventional magnet in which the same polar side of a magnet having a circular outer periphery is simply opposed with a space therebetween, since there is air as a good non-magnetic material between the opposed surfaces, it is possible to obtain a good magnetic flux density. Although it is not possible, since the center plate made of a magnetic material having a circular outer periphery is arranged between the opposing surfaces on the same pole side of the magnet, magnetic flux can be efficiently guided toward the outer peripheral portion of the magnet, and the diameter of the center plate can be increased. By setting the size larger than the diameter of the magnet and setting the size difference to 4 mm or less, it is possible to more effectively emit magnetic flux outward from the outer periphery of the center plate. In addition, the holder has a center guide portion at the center thereof and a mounting step at the lower portion thereof, and a step on the outer peripheral wall upper surface. By inserting or press-fitting into the center guide portion and inserting or press-fitting the outer peripheral portion of the outer plate into the step portion, each component can be easily installed at a predetermined position. A gap jig or the like sometimes used becomes unnecessary, and a magnetic gap having a predetermined interval can be accurately formed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic circuit for a loudspeaker according to the present invention will be described with reference to FIGS. 1 to 12. The same components as those of the prior art described with reference to FIGS. And a detailed description thereof will be omitted. As shown in FIGS. 1 and 2, the magnetic circuit for a loudspeaker according to the present invention includes:
In a speaker in which magnets 1A and 1B magnetized in the thickness direction are arranged at a predetermined interval so that the same poles face each other and a voice coil is arranged in a magnetic field generated by both magnets, the two magnets face each other. The outer peripheral circular center plate 2 made of a magnetic material is disposed so as to be clamped on the surface thereof, and a ring-shaped outer plate 3 made of a magnetic material is supported by a holder 4 outside the center plate. It is arranged such that a magnetic gap at a predetermined interval is formed between the inner peripheral portion 22 and the inner peripheral portion 31 of the outer plate. The magnets 1A and 1B used in the examples are neodymium-based magnets, and have an outer diameter of 29 mm, an inner diameter of 12 mm,
Two ring-shaped ones having a thickness of 6 mm are used, and the magnets 1A and 1B are respectively magnetized in the thickness direction. The center plate 2 is made of iron and has an outer diameter of 29.95 mm,
It has a ring shape with an inner diameter of 11.95 mm and a thickness of 4 mm,
The outer and inner ridges are chamfered by C0.4. The magnets 1A and 1B, the center plate 2
The holder 4 for supporting the outer plate 3 is made of aluminum and has a substantially bottomed cylindrical shape. A cylindrical center guide portion 41 protruding upward is provided at the center of the bottom portion 43 of the holder 4, and the magnets 1 </ b> A and 1 </ b> B and the center plate 2 are provided at the lower end of the center guide portion 41.
There is provided a mounting step 44 for positioning in the height direction.

After an acrylic adhesive is applied to the mounting step portion 44, the magnet 1B is inserted into the center guide portion 41 with the magnet inner diameter portion 1B1 facing the N pole upward. The outer diameter of the center guide part 41 is φ11.95 mm
It can be easily inserted. After applying an adhesive to the upper surface of the inserted magnet 1B, the inner diameter portion 21 of the center plate 2 is pressed into the center guide portion 41, and the lower surface of the center plate 2 is
The magnet 1A into the center guide portion 41 with the magnet 1A facing down and the magnet inner diameter portion 1A1 inserted into the center guide portion 41. Push down to the position where it comes into close contact with the upper surface of plate 2. With this, magnet 1
In A and 1B, the N poles face each other, and the center plate outer peripheral portion 22 is about 0.5 m larger than the outer peripheral portions 1A2 and 1B2 of the magnets 1A and 1B in a state where the center plate 2 is sandwiched.
It is installed in a state that it protrudes to the outside.

In this state, when the magnetic measurement probe is moved up and down about 0.5 mm further from the outer periphery 22 of the center plate, a magnetic distribution as shown in FIG. 3 is obtained, and an average value of about 6500 gauss is obtained. Was. By the way, the diameter of the center plate 2 is smaller than the diameters of the magnets 1A and 1B by 2 mm, that is, the diameter of the outer peripheral portion 22 of the center plate 2 is 1 mm inward from the outer peripheral portions 1A2 and 1B2 of the magnets 1A and 1B. When measured in the same manner as above, the value was 4000 to 4500 Gauss. From this, it seems most preferable that the diameter of the center plate 2 is set to be larger than the diameter of the magnets 1A and 1B, and that the difference between the sizes is set to 4 mm or less.

As shown in FIGS. 1 and 2, the holder 4 has a height near the upper end of the outer peripheral wall rising from the bottom 43 substantially equal to the position of the center plate. , Guide part 4 with inner diameter φ40mm and depth 2mm
The outer peripheral portion 32 of the iron outer plate 3 having an outer diameter of 39.9 mm, an inner diameter of 32.25 mm, and a thickness of 3 mm is pressed into the guide portion 42. After the press-fitting of the outer plate 3 is completed, a magnetic gap having an interval of 1.15 mm and an opposing width of 3 mm is completed between the inner peripheral portion 22 of the center plate 2 and the outer peripheral portion 32 of the outer plate.

When the magnetic measurement probe was moved up and down in the vicinity of the center of the magnetic gap and measured, a magnetic distribution as shown in FIG. 4 was obtained, and an average value of about 8500 gauss was obtained.
Further, the magnetic gap is divided into eight equal parts when viewed from above.
The points A to H were set as measurement points, and a magnetic measurement probe was inserted into the measurement points to perform measurement. As a result, point A 8100 (Gauss, the same applies hereinafter), point B 8450, point C 8750, point D 8500,
E point 8500, F point 8150, G point 7850, H point 79
As a result, a magnetic flux of about 8300 gauss could be obtained on average in the magnetic circuit. Also,
When the increase in the weight of the magnetic circuit portion is not taken into consideration, the performance of the magnetic circuit can be improved by making the thickness of the outer plate 3 larger than the thickness of the center plate 2. The thickness of 3 is 6
mm, the magnetic distribution as shown in FIG.
A magnetic flux of 0 Gauss could be obtained.

The holder 4 is provided with a flange portion 45 having a width of about 2 mm and a thickness of 2.5 mm facing the outer periphery of the guide portion 42 and a tongue-like mounting portion projecting outward from the flange portion 45. 46 are provided at four locations, and
6 is provided with a 4 mm tapping near the center. After applying a rubber-based adhesive to the flange portion 45, the bottom of the frame 5 is attached. As shown in FIG. 6, the frame 5 has a mounting hole of φ4.5 at a position corresponding to the tap. Magnetic circuit and frame 5 with 4 mm screws 6
Is fixed. The frame 5 is a so-called 6.5 inch with an outer diameter of about 165 mm and a depth of about 20 mm, and is made of a 0.7 mmt aluminum plate, a press frame, and weighs about 40 g. Vibration plate 7 as vibration system member
Has an outer diameter of approximately 134mm (including the edge) and a neck diameter of φ
A cone-shaped diaphragm made of pulp with a thickness of 31 mm and a depth of about 15 mmt is used.
(PPTA) film, with a coil winding width of 8 mm and a DC resistance of 3.43 Ω. The damper 9 is a general one obtained by impregnating a cotton cloth with phenol and thermoforming corrugation or the like. These vibrating members were assembled into the assembly of the magnetic circuit unit and the frame 5 and completed as a speaker and measured. As a result, characteristics shown by a solid line in FIG. 7 were obtained.

For comparison with the speaker manufactured in the above embodiment, the same vibration system as that of the speaker was used.
The frame is the same in shape, and only the material is used.
g) and a magnetic circuit that is also generally used conventionally (the top plate has an outer diameter of 75 mm and an inner diameter of 32 mm.).
25mm, thickness 4.5mm, magnet diameter φ85m
m, a ferrite magnet with an inner diameter of 45 mm and a thickness of 13 mm, and a speaker using a yoke with a pole diameter of 29.95 mm, a bottom outer diameter of 75 mm, and a height of about 20 mm) were measured. As shown by the dotted line in FIG. Characteristics were obtained. As is clear from the comparison of the characteristics, in the loudspeaker of the present invention, the characteristics in the low frequency range are slightly different, but characteristics that are practically acceptable can be obtained, and the impedance curve rises in a wider range than the conventional magnetic circuit. And the characteristic that the sound pressure level in the high range rises is confirmed. The weight of the magnetic circuit part in the embodiment of the present invention is about 95 g.
The total weight of the speaker was about 146 g. Therefore, in comparison with the weight of the magnetic circuit portion alone, the weight can be reduced by approximately 84% compared to the conventional magnetic circuit portion (603 g), and can be reduced by approximately 81% compared to the entire weight of the conventional speaker (780 g). It became.

In the case of this embodiment, the dimensions of each part obtained the characteristics shown by the solid line in FIG. 7 under the above-mentioned conditions, but the dimensions of each part can be freely designed according to the purpose of the speaker. In particular, the performance can be improved by examining the cross-sectional shapes of the center plate 2, the outer plate 3, and the like. In this embodiment, the outer plate 3 is held at a predetermined position by the holder 4.
Magnets 1A and 1B and center plate 2
Is held by the holder 4 and only the outer plate 3 is installed on the frame 5 side without any trouble.

Further, in the case of the present embodiment, the holder 4 is manufactured by cutting an aluminum material in consideration of the uniformity of the magnetic flux distribution above and below the magnetic circuit, the heat radiation effect, and the like. For example, the holder 4 may be formed of a heat-resistant resin such as PPS, or if it is not necessary to consider the uniformity of the magnetic flux distribution, the holder 4 may be made of a magnetic material, for example, 0.5 mmt or more.
Approximately the same performance can be obtained even if it is made of a 0.7 mm t iron plate or the like. Even when a magnetic material having a thickness equal to or greater than the thickness of the outer plate 3 is used, the strength for forming a magnetic circuit is ensured. The same effect can be obtained by cutting off as shown in FIG. 8 while leaving only the portion. In the case of this embodiment, since the holder 4 is manufactured by cutting, the average thickness of the holder 4 is 1.5 mm t. However, it is also possible to carry out a thinner processing than in this embodiment by press working or the like. Further, as shown in FIG. 9, a hole 47 or a fin 48 is provided in the holder 4 and a portion where the hole is formed is woven or non-woven fabric. The weight can be reduced and the heat radiation effect can be achieved by covering with a covering member 49 such as. In the present embodiment, the holder 4 is fixed with the screw 6, but may be fixed to the frame 5 by a conventionally generally used method such as caulking or welding. May be integrally molded as shown in FIG.

[0022]

According to the magnetic circuit for a speaker of the present invention,
By using a magnetic circuit as in the embodiment at least, it is possible to obtain a magnetic flux which is not different from the magnetic flux in the magnetic gap of the conventional speaker, and furthermore, a holder for holding a magnetic circuit member such as a magnet is made of non-metal such as aluminum. Since the magnetic material is used, the amount of iron in the magnetic circuit portion can be significantly reduced as compared with the conventional magnetic circuit portion, and the weight can be reduced by 84% as compared with the conventional magnetic circuit portion. Such a decrease in the amount of iron in the magnetic circuit portion makes it possible to suppress an increase in impedance over a wider range than in a conventional speaker, and to improve performance in a high frequency range. 1500 to 7000 particularly preferable for door mount
Hz high frequency characteristics and sound quality can be secured, and a feather cone or the like is attached to the upper end of the voice coil bobbin instead of the normal chamber to further extend the high frequency range and cover the range of conventional tweeters for high frequencies. Therefore, it is not necessary to use a tweeter for high-frequency sound unlike the related art, and it is possible to significantly reduce the weight of a door-mounted speaker or the like. In addition, the magnetic circuit of the embodiment is reduced in size as a result,
As the overall height of the speaker including the magnetic circuit is increased, the speaker is made thinner, and in particular, a form extremely suitable for a shape required for an in-vehicle speaker or the like can be obtained.

The holder is provided with a center guide at the center thereof, a mounting step at the lower portion thereof, and a step at the upper surface of the outer peripheral wall. By inserting or press-fitting into the center guide portion and inserting or press-fitting the outer peripheral portion of the outer plate into the step portion, each component can be easily installed at a predetermined position. A gap jig or the like used at the time of assembling becomes unnecessary, and a magnetic gap having a predetermined interval can be accurately formed.

Since the magnetic circuit portion is much lighter than the conventional one, the conventional 0.7 mmt iron plate-like frame is used to reduce the magnetic circuit part to 0.1 mm.
Even if the frame is changed to a 7 mmt aluminum frame, sufficient strength to support the weight of the magnetic circuit portion can be ensured and the weight can be effectively reduced. The overall weight of the speaker can be reduced by 81% or more. Since the aluminum frame is attached to the frame, the heat radiation effect is better than that of the conventional iron plate frame, and the cooling effect of the magnetic circuit part is increased, which is effective for power measures. Further, in the case of the magnetic circuit according to the present invention, since the magnetic circuit utilizes a repulsive magnetic field, there is a leakage magnetic field also on the S pole side as is clear from FIGS. Therefore, in order for the voice coil to have a uniform amplitude, it is preferable that the magnetic distribution in the vertical direction around the center plate, that is, in the amplitude direction of the diaphragm is symmetrical and uniform, and the frame is made of aluminum as in the embodiment of the present invention. It is very effective to use a non-magnetic material such as resin.

Further, for example, the holder can be processed to be thinner than the embodiment of the present invention, and furthermore, a hole or a fin is provided in the holder, and the hole is covered with a covering material, so that the magnetic circuit portion can be formed. Foreign matter, especially fine iron powder that enters the magnetic gap and generates abnormal noise, can be prevented from entering,
Moreover, there are effects such as weight reduction and magnetic circuit cooling. The reduction of the weight of the magnetic circuit portion by the drilling process can promote the reduction of the weight by reducing the thickness of the frame, and the weight can be reduced by integrally molding the frame and the holder. Further, for example, the magnetic flux distribution can be changed by changing the thickness of the center plate, the outer plate, and the like,
By examining the shapes of the parts and the like, it is possible to freely examine and set a magnetic circuit according to the purpose of the speaker.

[Brief description of the drawings]

FIG. 1 is a partial sectional perspective view of a speaker magnetic circuit according to the present invention.

FIG. 2 is an exploded perspective view of the speaker magnetic circuit of the present invention.

FIG. 3 is a sectional view and a magnetic flux distribution diagram in a state where an outer plate is not arranged.

FIG. 4 is a sectional view and a magnetic flux distribution diagram when the thickness of the outer plate is smaller than the thickness of the center plate.

FIG. 5 is a sectional view and a magnetic flux distribution diagram when the thickness of the outer plate is larger than the thickness of the center plate.

FIG. 6 is a sectional view of the speaker equipped with the magnetic circuit of the present invention.

FIG. 7 is a comparison characteristic diagram of a speaker equipped with the magnetic circuit of the present invention and a speaker equipped with a conventional magnetic circuit.

FIG. 8 is a sectional view showing another embodiment of the holder.

FIG. 9 is a sectional view showing still another example of the holder.

FIG. 10 is a cross-sectional view showing a state in which a hole of a holder is covered with a covering material.

FIG. 11 is a sectional view of a speaker in which the magnetic circuit of the present invention is mounted in another embodiment.

FIG. 12 is a cross-sectional view of the speaker when the holder and the frame are integrally formed.

FIG. 13 is a cross-sectional view of a speaker equipped with a conventional external magnet type magnetic circuit.

FIG. 14 is a cross-sectional view of a speaker equipped with a conventional inner magnet type magnetic circuit.

[Explanation of symbols]

 1A is an upper magnet 1B is a lower magnet 2 is a center plate 21 is a center plate inner peripheral portion 22 is a center plate outer peripheral portion 3 is an outer plate 31 is an outer plate inner peripheral portion 32 is an outer plate outer peripheral portion 4 is a holder 41 The center guide 42 is a step 43 is a holder bottom 44 is a mounting step 48 is a fin 49 is a covering member 5 is a frame 7 is a diaphragm 8 is a voice coil 9 is a damper

Continuation of the front page (56) References JP-A 63-44595 (JP, U) JP-A 61-128896 (JP, U) JP-B 60-3270 (JP, B1) (58) Fields surveyed (Int .Cl. ⁷ , DB name) H04R 9/02 102

Claims (2)

(57) [Scope of request for utility model registration] 1. A magnet (1A, 1B) having a circular outer circumference magnetized in a thickness direction is arranged at a predetermined interval so that the same pole side faces each other, and a voice coil is arranged in a magnetic field generated by both magnets. Speaker
A center plate (2) having a circular outer periphery made of a magnetic material is disposed so as to be sandwiched between opposing surfaces of the two magnets, and the diameter of the center plate is determined by the magnet (1).
A, 1B) A magnetic circuit for a loudspeaker, which is set to be larger than the diameter dimension of the speaker, and the dimensional difference is 4 mm or less. 2. Magnets (1A, 1B), which are magnetized in the thickness direction and have a circular outer circumference, are arranged at a predetermined interval so that the same poles face each other, and a voice coil is arranged in a magnetic field generated by both magnets. Speaker
A center plate (2) having a circular outer periphery made of a magnetic material is disposed so as to be sandwiched between opposing surfaces of the two magnets, and the magnets (1A, 1B) and the center plate (2) are formed in a ring shape, and are substantially provided. A center guide part (41) for inserting the center holes of the magnets (1A, 1B) and the center plate (2) is held at the center of the holder by a holder made of a non-magnetic material having a bottom cylindrical shape. The center guide portion (4
A magnetic circuit for a loudspeaker, wherein a mounting portion (44) for supporting a magnet and a center plate is formed at a lower portion of 1).