JPS6022712Y2 - Speaker magnetic circuit - Google Patents

Description

[Detailed explanation of the idea] This invention relates to the magnetic circuit of a speaker.

Conventionally, a speaker has a voice coil 5 disposed in the gap between a plate 2 and a pole piece 3 of a magnetic circuit as shown in FIG. An alternating current magnetic flux is generated near the coil, and via the plate and pole piece placed near the voice coil,
When this alternating magnetic flux flows, the inductance of the voice coil becomes nonlinear due to the magnetic nonlinearity of the magnetic materials of the plate and pole piece, causing distortion in the current flowing through the voice coil.

As a result, the driving force generated by the current flowing through the voice coil also has non-linearity, causing harmonic distortion in the sound reproduced by the speaker, which significantly impairs the sound quality.

The present invention provides a magnetic circuit for a speaker that can remove the above-mentioned harmonic distortion components.

Embodiments of the present invention will be described below with reference to the drawings.

In Figure 2, 1 is the speaker frame, 2 is the plate, 3 is the pole piece, 4 is the magnet, 5 is the voice coil, 6 is the diaphragm, 7 is the spider, and 8 is the center cap, and these are the conventional ones. It is similar.

12 is a ring of a high magnetic permeability member fixed to the outer circumference of the pole piece 3; 11 is a ring of high magnetic permeability member fixed to the inner circumference of the plate 2; 13 is a ring of high magnetic permeability member of the ring 11; A ring 14 is made of a non-magnetic metal with good conductivity fixed to the upper and lower surfaces of the ring 12, and 14 is a high magnetic permeability member. It is a ring that has been made.

In the magnetic circuit of the speaker configured in this way, rings 11 and 12 made of a material with higher magnetic permeability than the soft iron commonly used are attached to the magnetic gap, and further rings made of a material with high magnetic permeability are attached. 11.12 Rings 13.1 formed of a non-magnetic metal with good conductivity on the upper and lower surfaces, respectively.
4, the rings 13, 14 act as short-circuited secondary coils for the voice coil 5, thereby reducing the inductance of the voice coil 5 and reducing the alternating current induced magnetic flux.

Furthermore, since the AC induced magnetic flux generated by the voice coil 5 acts on the rings 11 and 12 formed of high magnetic permeability material, hysteresis loss is extremely reduced and the AC current flowing through the voice coil 5 is not adversely affected.

Therefore, the harmonic components of the alternating current flowing through the voice coil 5 due to the magnetic circuit are reduced, and the harmonic components of the sound reproduced by the speaker are reduced.

In addition, the above effect becomes even more remarkable by making the ring 12 attached to the pole piece 3 side longer than the ring 11 attached to the plate 2 side in FIG.

Figures 3 and 4 show the frequency characteristics of the sound pressure generated by speakers using a conventional magnetic circuit and a magnetic circuit according to the present invention. Curve C is the frequency characteristic of the second harmonic caused by the circuit, curve C is the frequency characteristic of the second harmonic caused by the magnetic circuit of this invention, curve a is the frequency characteristic of the fundamental wave in FIG. Curve C shows the frequency characteristic of the third harmonic due to the magnetic circuit of this invention.

FIG. 5 shows another embodiment of this invention.

In this embodiment, when a white magnetic type magnetic circuit is used, 9 indicates a yoke, and 10 indicates a center ring.

It is possible to use a bark that is a combination of known examples such as those shown in Japanese Patent Publication No. 50-23613 and Japanese Patent Publication No. 50-7514, but the bark of this invention is a combination of the barks as described below. It has advantages compared to other things.

For convenience of explanation, the main parts of this invention and the combination of the above-mentioned known examples are shown in Fig. 6a,
Shown in b.

In FIG. 6, 15 indicates a good conductor.

In FIG. 6, the air gap length 1g must be sufficient to accommodate the voice coil.

Therefore, when using the same voice coil, both a and b in FIG. 6 must be set to the same 1g.

Therefore, in the case of the air gap length 1g' shown in FIG. 6, the magnetic air gap becomes larger by the thickness t of the conductive member 15.

In other words, the inequality Ig'=1g+t: Ig'>Ig holds true.

Assuming that the magnets used here are of the same size, Figure 6a
Explain that this is better than the one in Figure 6.

As is well known, the magnetic air gap length IgV changes with 1g', and since Ig'>Ig, the magnetic flux density Bg in Fig. 6A is the magnetic flux density Bg in Fig. 6a. It becomes smaller than Bg.

Therefore, since the output sound pressure level, which is one of the specifications that determines the quality of the acoustic characteristics of a speaker, is proportional to the magnetic flux density Bg2, it follows that the acoustic characteristics of the speaker according to Figure 6a are better than those shown in Figure 6. .

Furthermore, compared to the example shown in Figure 6, the example shown in Figure 6a does not have a good conductor 15 in the air gap, so at first glance it seems to be inferior in terms of removing the second harmonic, but as mentioned above, Since the output sound pressure level is proportional to the magnetic flux density, the ratio of the square of the magnetic flux density of the fundamental wave component to the square of the magnetic flux density of the second harmonic component is the ratio of the sound pressure level.

Therefore, if the sound pressure levels are compared as a result, the fundamental wave component is sufficiently larger than the second harmonic component.

As mentioned above, compared to the magnetic circuit of conventional speakers, the magnetic circuit of this invention has a high magnetic permeability material in the air gap and good conductivity materials on the top and bottom surfaces, which reduces the voice coil inductance. In addition to reducing the AC induced magnetic flux caused by the voice coil current, it also reduces hysteresis loss, which reduces current distortion caused by the magnetic circuit, and reduces harmonic components of the sound reproduced by the speaker. It is possible to reduce the

[Brief explanation of drawings]

Figure 1 is a partial cross-sectional view showing the magnetic circuit of a conventional speaker.
Fig. 2 is a partial sectional view showing the magnetic circuit of a speaker showing an embodiment of this invention, Fig. 3 is a frequency characteristic diagram of the second harmonic due to the magnetic circuit of the speaker, and Fig. 4 is a diagram showing the frequency characteristics of the second harmonic due to the magnetic circuit of the speaker. FIG. 5 is a partial sectional view of the magnetic circuit of a speaker showing another embodiment; FIG. 6 is a diagram showing the main parts of the magnetic circuit to explain the effects of this invention; FIG. 6a is a partial cross-sectional view showing the main part of a magnetic circuit according to an embodiment of the present invention, and FIG. 6A is a partial cross-sectional view showing the main part of a magnetic circuit of a virtual combination of known examples. In addition, the same reference numerals in the figures indicate the same or equivalent parts, 1 is the frame, 2 is the plate, 3 is the pole piece, 4 is the magnet, 5 is the voice coil, 6 is the diaphragm, 7 is the spider, 8 is the center cap, 9 is a yoke, 10 is a center ring, 11° and 12 are rings made of high magnetic permeability material,
Reference numerals 13 and 14 indicate rings made of a material with good conductivity.

Claims (1)

[Scope of utility model registration request] A magnetic circuit having a structure in which a magnet 4 supplies magnetic flux to an air gap created between the plate 2 or yoke 9 and the pole piece 3 is used, a voice coil 5 is installed in the air gap, and the conductor of this voice coil is In a speaker having a structure in which the voice coil is driven by applying an alternating voltage to the diaphragm 6, and this driving force is transmitted to the diaphragm 6, the circumferences of both the pole piece and the plate or yoke forming the above-mentioned gap facing the gap are Rings 11 and 12 made of a material with higher magnetic permeability than the soft iron used for pole pieces, plates, or yokes are attached to the upper part, and a non-magnetic metal with good conductivity is attached to both the upper and lower surfaces of the ring. A magnetic circuit for a speaker, characterized in that a ring 13 or 14 formed of a member is attached.