JP2006020139A - Speaker magnetic circuit and speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive outer-magnetic type magnetic circuit keeping flux density distribution of magnetic air gap high in a wide range, and raising average flux density necessarily and sufficiently, as a speaker with an especially high output sound pressure required and for a speaker magnetic circuit used therefor. <P>SOLUTION: The speaker magnetic circuit comprises a plate, a main magnet of which the upper surface is fixed at the lower surface of the plate, a yoke of which the flat surface plate is fixed at the lower surface of the main magnet, a first sub magnet of which the lower surface is fixed at the upper surface of the pole of the yoke, a pole piece of which the lower surface is fixed at the upper surface of the first sub magnet, and a second sub magnet of which the lower surface is fixed at the upper surface of the pole piece. The main magnet, the first sub magnet, and the second sub magnet, which are made magnetic respectively, are in a same pole at the lower surface side of the main magnet, the upper surface side of the first sub magnet, and the lower surface side of the second sub magnet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a speaker magnetic circuit, and more particularly to a speaker required to have a high output sound pressure and a speaker magnetic circuit used therefor.

  4A is a plan view for explaining a conventional magnetic circuit 1 for a speaker, and FIG. 4B is a cross-sectional view taken along line A-A ′. The speaker magnetic circuit 1 includes a plate 2, a pole piece 3, and a main magnet 4, and an inner diameter side surface of the plate 2 and an outer diameter side surface of a pole portion of the pole piece 3 define a magnetic gap 5. The main magnet 4 has a top surface fixed to the bottom surface of the plate 2 and a bottom surface fixed to the flat plate portion of the pole piece 3 and is typically a ferrite-based magnet having ferromagnetism. It is located outside the region defined by the gap 5. The speaker magnetic circuit 1 is generally called an outer magnet type magnetic circuit and is used in many speakers because it is inexpensive with respect to the obtained performance.

  In a speaker that requires high output sound pressure, it is necessary to increase the magnetic flux density B of the magnetic gap 5, and in the case of an external magnet type magnetic circuit, the main magnet 4 is enlarged, for example. This can be done by increasing the magnetic force. FIG. 2 is a graph showing the distribution of the magnetic flux density B in the magnetic air gap 5 of the speaker magnetic circuit 1. For example, the curve (b) represents an example of a conventional outer magnet type magnetic circuit of a speaker having a diameter of 8 cm, which is about 0.98 Tesla at the highest magnetic flux density. For example, in order to increase the magnetic flux density B to 1.0 Tesla or more with an external magnet type magnetic circuit, there is a problem that the weight of the magnetic circuit and the whole speaker becomes heavy because the main magnet 4 becomes considerably large.

  FIG. 5 is a cross-sectional view for explaining another conventional magnetic circuit 1 for a speaker. FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view along A-A ′. The speaker magnetic circuit 1 is an internal magnetic circuit in which a magnet is located inside a region defined by the magnetic gap 5 when viewed in plan, and the magnets 6 and 8 having the same polarity with the top plate 7 interposed therebetween. Is a repulsive magnetic circuit that faces each other. In the inner magnet type magnetic circuit and the repulsive type magnetic circuit, the weight of the magnetic circuit and the entire speaker can be reduced, but in order to sufficiently increase the magnetic flux density B of the magnetic gap 5, an expensive magnet such as a neodymium magnet is used. In order to ensure magnetomotive force, it must be used in a large size, which is disadvantageous in terms of cost.

  Conventionally, in order to increase the magnetic flux density of the magnetic gap of an inexpensive outer magnet type magnetic circuit, a fixed magnet is newly provided on the upper surface of the center pole of the outer magnet type magnetic circuit, and the magnetic pole on the center pole side of the fixed magnet is There is one that has the same pole surface as the magnetic pole generated at the center pole of the outer magnet type magnetic circuit (Patent Document 1).

Japanese Patent Laid-Open No. 10-112896 (FIGS. 1 to 4)

  However, in the external magnetic type magnetic circuit for a speaker according to the prior art, when a particularly high output sound pressure is required for a small speaker, the magnetic flux density of the magnetic gap may not be sufficiently increased. When a fixed magnet is newly provided on the upper surface of the center pole of the outer magnetic circuit (FIG. 4 of Patent Document 1), the magnetic flux density distribution (curve a) in the range where the voice coil is located is the conventional value ( There is a case where a range exceeding the curve b) and a range below the curve b) may coexist, resulting in a problem that the average magnetic flux density cannot be sufficiently increased.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention relates to a speaker magnetic circuit, and particularly a speaker that requires a high output sound pressure and a speaker magnet used therein. It is an object of the present invention to provide a magnetic circuit for a speaker that is an inexpensive outer magnet type magnetic circuit and that can maintain a high magnetic flux density distribution in a magnetic gap over a wide range and increase an average magnetic flux density as necessary and sufficiently.

  The speaker magnetic circuit of the present invention is a speaker magnetic circuit in which a plate inner diameter side surface and a pole piece outer diameter side surface define a magnetic gap, and a main magnet having an upper surface portion fixed to the plate and the plate lower surface portion. And a yoke having the flat plate portion fixed to the lower surface portion of the main magnet, a first sub magnet having the lower surface portion fixed to the upper surface of the pole portion of the yoke, and a lower surface portion fixed to the upper surface portion of the first sub magnet. A pole piece and a second sub-magnet whose lower surface is fixed to the upper surface of the pole piece, and the polarities of the magnetized main magnet, first sub-magnet, and second sub-magnet are respectively on the lower surface side of the main magnet The same polarity is provided on the upper surface side of the first sub magnet and the lower surface side of the second sub magnet.

  Furthermore, in the speaker magnetic circuit of the present invention, when the speaker magnetic circuit is viewed in plan, the main magnet is located outside the region defined by the magnetic gap, and the first submagnet and the second submagnet are magnetic gaps. Located inside the defined area.

  Further preferably, in the speaker magnetic circuit of the present invention, the main magnet is a ferrite magnet, and the first submagnet and the second submagnet are neodymium magnets.

  Further preferably, the magnetic circuit for a speaker according to the present invention further includes a connection fixing member, and the connection fixing member connects and fixes the upper surface of the pole portion of the yoke and the pole piece.

  Furthermore, a speaker of the present invention includes any one of the above-described speaker magnetic circuits of the present invention, a voice coil disposed in a magnetic gap of the magnetic circuit, and a diaphragm to which the voice coil is connected.

  The operation of the present invention will be described below.

  In the magnetic circuit for a speaker according to the present invention, the inner diameter side surface of the plate and the outer diameter side surface of the pole piece define a magnetic gap. In addition, the polarities of the magnetized main magnet, the first sub-magnet, and the second sub-magnet fixed to the plate and the pole piece are set to the lower side of the main magnet, the upper side of the first sub-magnet, and the second sub-magnet, respectively. It has the same polarity on the lower surface side. Therefore, in the magnetic circuit for a speaker according to the present invention, the magnetic flux density distribution of the magnetic gap is obtained by synthesizing the magnetic flux generated by the magnetomotive force of the main magnet and the magnetic flux repelled by the magnetomotive force of the first submagnet and the second submagnet. It can be kept high and the average magnetic flux density can be increased sufficiently. As a result, the magnetic flux density of the magnetic gap can be increased as compared with the conventional speaker magnetic circuit. In a preferred embodiment, the speaker of the present invention further includes a voice coil disposed in the magnetic gap of the magnetic circuit and a diaphragm connected to the voice coil, and uses the speaker magnetic circuit of the present invention. Thus, a speaker capable of reproducing with a high output sound pressure is provided.

  In a preferred embodiment, in the speaker magnetic circuit of the present invention, when the speaker magnetic circuit is viewed in plan, the main magnet is located outside the region defined by the magnetic gap, and the first submagnet and the second submagnet Is located inside the region defined by the magnetic gap. The main magnet constitutes a so-called external magnetic circuit, and the first sub-magnet, pole piece and second sub-magnet constitute a so-called repulsive magnetic circuit. As a result, the magnetic gap is smaller than that of a conventional speaker magnetic circuit. Magnetic flux density can be increased. In the magnetic circuit for a speaker according to the present invention, the magnetic flux generated by the external magnetic circuit and the magnetic flux generated by the repulsive magnetic circuit do not cancel each other within the range of the magnetic gap. The magnetic flux distribution in the magnetic gap is improved symmetrically in comparison with the case where a fixed magnet is newly provided on the magnetic gap. Therefore, the magnetic circuit for a speaker according to the present invention can keep the magnetic flux density distribution of the magnetic gap high in a wide range, and can increase the average magnetic flux density as necessary and sufficient.

  In a preferred embodiment, in the speaker magnetic circuit of the present invention, the main magnet is a ferrite magnet, and the first submagnet and the second submagnet are neodymium magnets. Therefore, an inexpensive ferrite-based magnet can be used as the main magnet, and an expensive but strong magnetomotive force neodymium-based magnet can be used in a small volume as the first submagnet and the second submagnet, so that the magnetic flux density distribution of the magnetic gap is kept high. On the other hand, the cost of the entire speaker magnetic circuit can be reduced.

  In a more preferred embodiment, the magnetic circuit for a speaker according to the present invention further includes a connection fixing member, and the connection fixing member connects and fixes the upper surface of the pole portion of the yoke and the pole piece. The connection fixing member is, for example, a screw, and is connected to a screw hole provided in the upper surface of the pole portion of the yoke through a through hole provided in the pole piece. In the process of completing the speaker magnetic circuit of the present invention, the outer magnet type magnetic circuit composed of the main magnet and the repulsive type magnetic circuit composed of the first sub-magnet, pole piece and second sub-magnet are respectively magnetized. These may be connected by a connection fixing member. Therefore, it is possible to easily obtain a speaker magnetic circuit that can keep the magnetic flux density distribution of the magnetic gap of the present invention high in a wide range.

  The magnetic circuit for a speaker and the speaker of the present invention are an inexpensive external magnet type magnetic circuit, particularly in a speaker that requires a high output sound pressure and a magnetic circuit for a speaker used in the speaker. It is possible to provide a magnetic circuit for a speaker that can be kept high over a wide range and can increase the average magnetic flux density sufficiently and sufficiently.

  The speaker magnetic circuit of the present invention is an inexpensive outer magnet type magnetic circuit, which aims to maintain the magnetic flux density distribution of the magnetic gap high in a wide range and increase the average magnetic flux density as necessary and sufficiently. And the magnetic flux repelled by the magnetomotive force of the first submagnet and the second submagnet.

  Hereinafter, a magnetic circuit for a speaker and a speaker according to preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

  FIG. 1 is a diagram illustrating a speaker magnetic circuit 1 according to a preferred embodiment of the present invention. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along the line A-A ′. The speaker magnetic circuit 1 includes a plate 2, a yoke 3, a pole piece 7, a main magnet 4, a first submagnet 6, and a second submagnet 8.

  The plate 2, the yoke 3, and the pole piece 7 are typically made of a metal such as iron or a soft magnetic material such as ferrite. For example, the plate 2 and the pole piece 7 are disk-shaped metal plates. The plate 2 is provided with a through hole, and the inner diameter side surface of the through hole of the plate 2 and the outer diameter side surface of the pole piece 7 are magnetic for speakers. The magnetic air gap 5 of the circuit 1 is defined. The yoke 3 includes a flat plate portion 3a and a pole portion 3b protruding in the center of the flat plate portion 3a. The main magnet 4, the first sub magnet 6 and the second sub magnet 8 are ferromagnetic magnets, and have a magnetomotive force and a coercive force when magnetized. Here, the main magnet 4 is a ferrite magnet, and the first sub magnet 6 and the second sub magnet 8 are neodymium magnets.

  The lower surface portion of the plate 2 is fixed to the upper surface portion of the main magnet 4, and the lower surface portion of the main magnet 4 is fixed to the flat plate portion 3 a of the yoke 3. The first sub magnet 6 has a lower surface portion fixed to the upper surface of the pole portion 3b of the yoke 3, the pole piece 7 has a lower surface portion fixed to the upper surface portion of the first sub magnet 6, and the second sub magnet 8 has The lower surface portion is fixed to the upper surface portion of the pole piece 7. The height of the pole portion 3b of the yoke 3 is such that the inner diameter side surface of the plate 2 and the outer diameter side surface of the pole piece 7 face each other. As a result, the magnetic gap 5 is defined by the inner diameter side surface of the plate 2 and the outer diameter side surface of the pole piece 7. Each component is fixed by prescribing the positional relationship between the components using an assembly jig and fixing the components with an adhesive.

  Here, when the speaker magnetic circuit 1 is viewed in a plan view, the main magnet 4 is located outside the region defined by the magnetic gap 5, so to speak, constitutes an outer magnet type magnetic circuit. The first submagnet 6 and the second submagnet 8 are located inside the region defined by the magnetic gap 5 and constitute a repulsive magnetic circuit. The polarities of the magnetized main magnet 4, the first sub magnet 6 and the second sub magnet 8 are on the lower surface side of the main magnet 4, the upper surface side of the first sub magnet 6 and the lower surface side of the second sub magnet 8. Are of the same polarity. Therefore, in the speaker magnetic circuit 1 of the present invention, by synthesizing the magnetic flux generated by the magnetomotive force of the main magnet 4 and the magnetic flux repelled by the magnetomotive force of the first submagnet 6 and the second submagnet 8, the magnetic gap The magnetic flux density distribution can be kept high, the vertical symmetry of the magnetic flux density distribution can be improved, and the average magnetic flux density can be increased sufficiently.

  In terms of cost, the magnet occupies a high ratio among the components of the speaker magnetic circuit 1. The main magnet 4 of the speaker magnetic circuit 1 is an inexpensive ferrite-based magnet, and the first sub-magnet 6 and the second sub-magnet 8 may be neodymium-based magnets that are expensive but have a strong magnetomotive force. Therefore, since an expensive neodymium magnet having a strong magnetomotive force can be used in a small volume as the first submagnet 6 and the second submagnet 8, the magnetic flux density distribution of the magnetic gap 5 can be kept high, while the speaker The cost of the magnetic circuit 1 as a whole can be reduced.

  FIG. 2 is a diagram showing the magnetic flux density distribution of the magnetic air gap 5 of the speaker magnetic circuit 1. A curve (a) is an embodiment of the speaker magnetic circuit 1 according to the present invention, and a curve (b) is a comparative example of a prior art outer magnet type magnetic circuit. Are the same. Here, the curve (a) showing the example shows a magnetic flux density having a high value of about 1.40 [T] in the range t1 corresponding to the thickness dimension of the plate 2 or the pole piece 7, and is a comparative example. A value higher than the curve (b) showing can be obtained. Furthermore, even in the range t2 where the voice coil is located, the curve (a) indicating the example does not fall below the curve (b) indicating the comparative example. Therefore, in the speaker magnetic circuit 1 of the present invention, as a result, the average magnetic flux density can be sufficiently increased. In addition, a present Example and a comparative example are the magnetic circuits 1 used for a speaker provided with the cone-shaped diaphragm of 8 cm in diameter, Comprising: Thickness dimension t1 = 4.0mm of the plate 2 and the pole piece 7, and a voice coil are located The range t2 = 6.0 mm.

  The speaker (not shown) of the present invention including the speaker magnetic circuit 1 further includes a voice coil disposed in the magnetic gap 5 and a diaphragm connected to the voice coil. Since the magnetic flux density distribution of the magnetic gap 5 can be kept high, the speaker of the present invention can be reproduced with a high output sound pressure by using the speaker magnetic circuit 1. For example, the output sound pressure level of a speaker having a cone type diaphragm having an aperture of 8 cm is 83.1 dB / W / m in the comparative example in the case of the example of FIG. Then, 84.6 dB / W / m can be realized. At the same time, since the cost of the speaker magnetic circuit 1 is reduced, the cost of the entire speaker can be reduced even if the speaker is required to be reproduced with a high output sound pressure.

  The speaker magnetic circuit and the speaker of the present invention are not limited to the aperture and dimensions of the above-described embodiments. Even a speaker with another diameter is not limited to these embodiments as long as the speaker has a magnetic circuit using a ferrite magnet as a main magnet.

  FIG. 3 is a diagram illustrating a speaker magnetic circuit 1 according to another preferred embodiment of the present invention. FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view along A-A ′. The speaker magnetic circuit 1 includes a plate 2, a yoke 3, a pole piece 7, a main magnet 4, a first submagnet 6, a second submagnet 8, and a connecting and fixing member 9. For example, the connecting and fixing member is a non-magnetic screw 9, and the screw 9 connects and fixes the upper surface of the pole portion 3 b of the yoke 3 and the pole piece 7. Specifically, the first sub-magnet 6, the pole piece 7 and the second sub-magnet 8 are provided with through holes, and the screw 9 passes through these through-holes and has a screw hole 3c provided on the upper surface of the pole portion 3b of the yoke 3. Link.

  In the process of completing the speaker magnetic circuit 1 of the present invention, an outer magnet type magnetic circuit comprising a main magnet 4 and a repulsive type magnetic circuit comprising a first sub magnet 6, a pole piece 7 and a second sub magnet 8 are respectively provided. It is only necessary to magnetize them and connect them with screws 9 which are connecting and fixing members. The components of the outer magnet type magnetic circuit and the repulsive type magnetic circuit are fixed by fixing the components with an adhesive. Thereafter, the magnetic gap 5 is defined using an assembly jig, and the external magnetic type magnetic circuit and the repulsive type magnetic circuit are connected by the screw 9. Since magnetic force acts between the magnetized outer magnetic type magnetic circuit and repulsive type magnetic circuit, it is difficult to define the magnetic circuit 5 by bringing them close to each other. As compared with the case where it is fixed only by this, the assembly jig can be removed before the adhesive is completely solidified. By doing so, the number of speaker magnetic circuits 1 that can be manufactured per unit time can be increased, and as a result, the manufacturing cost of the speaker magnetic circuit 1 can be reduced.

  In this embodiment, the connecting and fixing member 9 is a non-magnetic screw 9, but the present invention is not limited to this. Any means can be used as long as the magnetic force acting between the magnetized outer magnet type magnetic circuit and the repulsive type magnetic circuit can be connected with a larger force before the adhesive is completely solidified. For example, the connection fixing member 9 may be a protrusion provided on the upper surface of the pole portion 3b of the yoke 3, and the external magnetic type magnetic circuit and the repulsive type magnetic circuit are connected by caulking the protrusion. Also good. By connecting with the connecting and fixing member 9, the manufacturing cost can be reduced if the assembly jig can be removed before the adhesive is completely solidified, as compared with the case of fixing with the adhesive alone.

  The magnetic circuit for a speaker and the speaker of the present invention are particularly useful in a speaker that requires a particularly high output sound pressure and a magnetic circuit for a speaker used in the speaker. In particular, since the magnetic flux density distribution of the magnetic gap can be kept high in a wide range, it is suitable for a large speaker with a large displacement of the diaphragm and a speaker for a subwoofer device for supplementing bass reproduction capability.

It is a figure explaining the magnetic circuit for speakers by preferable embodiment of the present invention. (Example 1) It is a graph showing distribution of the magnetic flux density B in the magnetic space | gap of the magnetic circuit for speakers. It is a figure explaining the magnetic circuit for speakers by other preferred embodiments of the present invention. (Example 2) It is a figure explaining the conventional magnetic circuit for speakers. It is a figure explaining the other conventional magnetic circuit for speakers.

Explanation of symbols

1 Magnetic circuit for speaker 2 Plate 3 Yoke, pole piece 4 Main magnet 5 Magnetic gap 6 First sub magnet 7 Pole piece 8 Second sub magnet 9 Connecting member

Claims (5)

The plate inner diameter side and the pole piece outer diameter side are magnetic circuits for speakers that define a magnetic gap,
The plate;
A main magnet whose upper surface is fixed to the lower surface of the plate;
A yoke having a flat plate fixed to the lower surface of the main magnet;
A first submagnet having a lower surface portion fixed to an upper surface of the pole portion of the yoke;
The pole piece whose lower surface is fixed to the upper surface of the first sub-magnet;
A second sub-magnet whose lower surface is fixed to the upper surface of the pole piece;
The polarities of the magnetized main magnet, the first sub magnet, and the second sub magnet are respectively on the lower surface side of the main magnet, the upper surface side of the first sub magnet, and the lower surface side of the second sub magnet. The same polarity,
Magnetic circuit for speakers. When the speaker magnetic circuit is viewed in plan, the main magnet is located outside the region defined by the magnetic gap, and the first submagnet and the second submagnet are defined by the magnetic gap. The magnetic circuit for a speaker according to claim 1, wherein the magnetic circuit is located inside. The speaker magnetic circuit according to claim 1 or 2, wherein the main magnet is a ferrite magnet, and the first submagnet and the second submagnet are neodymium magnets. 4. The speaker magnetic circuit according to claim 1, further comprising a connection fixing member, wherein the connection fixing member connects and fixes the upper surface of the pole portion of the yoke and the pole piece. 5. A speaker comprising: the speaker magnetic circuit according to claim 1; a voice coil disposed in a magnetic gap of the magnetic circuit; and a diaphragm connected to the voice coil.