JPS581036Y2 - Speaker magnetic circuit - Google Patents

Description

[Detailed description of the invention] The present invention relates to a magnetic circuit for a speaker that obtains high magnetic flux density in the magnetic air gap.In particular, by reducing the inductance of the voice coil, the high range of the sound pressure frequency characteristic is improved. It has improved characteristics.

Generally, in order to obtain sufficient acoustic output from a speaker, the electroacoustic conversion effect is improved by increasing the magnetic flux density Bg of the magnetic gap and increasing the output sound pressure level.

For example, in a medium or treble speaker, 18,000 Gauss (GauSS) is required to obtain the desired sound pressure level.
A magnetic flux density Bg of ~24,000 Gauss (GauSS) may be obtained in the magnetic air gap.

Therefore, conventionally, the above-mentioned 1&000 GauSS ~ 2
In order to obtain a magnetic flux density Bg of 4000 GauSS, a magnetic circuit of a speaker configured as shown in FIGS. 1 and 2 is added.

That is, in an internal magnetic type magnetic circuit as shown in FIG. At least the portion of the plate 4 disposed at the upper end of the yoke 1 facing the pole piece 3 is made of permendur, which is also a high magnetic permeability material. ing.

Furthermore, in an external magnetic type magnetic circuit as shown in FIG. At least the portion of the plate 4 disposed at the upper end of the magnet 2 disposed on the outer circumferential side facing the pole piece 3 is made of permendur, which is also a high magnetic permeability material.

Nao, the permendur used here is cobalt co...11.・・・・・・－・50% Panadium V・・・・・・・・・・・・2~3 da iron・・・・・・
・・・・・・・・・・・・・・・・・・・・・・-The alloy with the remainder.

This permendur ranges from 18,000 QauSS to 24,000 QauSS necessary to obtain the desired sound pressure level.
If the magnetic flux density Bg is much higher than that of GauSS, magnetic saturation will not occur.

Sunajcchi, 18.0OQGBu88~241000G
When trying to obtain the magnetic flux density Bg of the auSS in the magnetic air gap pJvc, the permendur forming part of the pole piece 3 and the plate 4 is in a state of not being magnetically saturated, so it is disposed in the magnetic air gap.

The magnetic permeability μ near the voice coil becomes extremely large.

For example, when the magnetic flux density BgIJ''-1&000Gau88, μ
m800 When the magnetic flux density Bg is 22.0OOGauSS, it is μm50.

In this way, as μ increases, the impedance in the voice coil increases.

Since the impedance of the voice coil increases in proportion to the frequency, the sound pressure level inevitably decreases in high frequency bands.

Therefore, the sound pressure frequency characteristics in the high range of the speaker deteriorate.

For this reason, in order to prevent the impedance in the voice coil from becoming steep especially in the high range, it is necessary to reduce μ near the voice coil.

In order to reduce this μ, conventionally, as shown in FIGS. 3 and 4, a cap 5 made of copper (Cu), which is a magnetic insulating material, is attached to the upper end of the pole piece 3 facing the plate 4. A dark magnetic circuit is marked on it.

However, since the copper (Cu) constituting the cap 5 magnetically insulates the gap between the cap 5 and the pole piece 3, it increases the magnetic gap area, making it extremely inefficient as a magnetic circuit. becomes.

Therefore, in the present invention, in a device having a pole piece made of a high magnetic permeability material such as permendur, the above-mentioned magnetic material is used to achieve magnetic saturation with respect to the desired magnetic flux density Bg in the magnetic gap. It is placed in the part of the pole piece facing the magnetic gap, and by reducing μ near the voice coil and reducing the impedance in the voice coil, it aims to improve the sound pressure frequency characteristics of the speaker, especially in the high range. This is what I did.

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

FIG. 5 shows an internal magnetic type J) magnetic circuit according to the present invention, in which a magnet 12 is arranged at the center of the inner side of a pot-shaped yoke 11, and a pole piece 13 is arranged at the upper end of this magnet 12. It is set up.

Further, the above-mentioned pole piece 1 is attached to the upper end of the above-mentioned yoke 11.
A play river 4 is arranged so as to face the magnetic field 3, forming a magnetic gap.

In order to maintain the output sound pressure level necessary to obtain sufficient acoustic output from the speaker, the magnetic flux density Bg of the magnetic air gap is set from 1&0OOGauSS to 24000GauSS.
The pole piece 13 is made of permendur, which is a high magnetic permeability material, as described above, so as to form a magnetic field of about 100 mL.

As mentioned above, this permendur is 18,000 GauSS to 24,000 GauSS in the magnetic gap.
When attempting to obtain a magnetic flux density of

Therefore, the upper end 15 of the pole piece 13 facing the magnetic gap is made of a magnetic material that is sufficiently magnetically saturated at a magnetic flux density of 18,000 Gauss or less.

Further, the plate 14 is also made of a similar magnetic material.

As such a magnetic material, 5UYX S-15c
Materials such as SS-340 steel and silicon steel plates are used.

Such a material has a magnetic flux density of BglJ″-18,000Gaus SJ), as shown below.
When μ±15~20 When magnetic flux density Bg is 22=000 GauSS μm8
10 to 15 μm=1 in a magnetically saturated state.

By disposing such a magnetic material in a portion facing the magnetic gap of the pole piece 13 that forms a magnetic field with a magnetic flux density of 18so00Gauss or more, it is possible to reduce μ in the vicinity of the voice coil and thereby reduce impedance in the voice coil. .

Furthermore, Fig. 6 shows an external magnetic type magnetic circuit according to the present invention, and in this case as well, like the internal magnetic type described above, it is constructed of permendur which is a high magnetic permeability material. 18,0 at the upper end 15 of the piece 13 facing the magnetic gap.
The plate 14 is made of a magnetic material such as the one described above that is magnetically saturated at a magnetic flux density of 00 Gauss or less.Furthermore, the plate 14 is also made of a similar magnetic material.

Then, the same effect as shown in FIG. 5 can be obtained.

In addition, Paul Bi piece 1 made of permendur
18sOOO arranged in the part facing the magnetic gap of No. 3
A magnetic material that magnetically saturates at a magnetic flux density below GauSS is
As shown in FIGS. 7 and 8, the pole piece 13
A ring portion 25 may be provided on the outer periphery of the upper end.

As mentioned above, by configuring the magnetic circuit of the speaker, a material with an extremely high magnetic field density, such as permendur, is used for the pole piece, so the output sound is reduced to obtain sufficient acoustic output from the speaker. The magnetic flux density Bg of the magnetic gap required to increase the pressure level is 18 = 000 GauS
S
Due to the magnetic material that magnetically saturates at a magnetic flux density below uSS,
It is used in a magnetically saturated region in the magnetic gap.

Therefore, without increasing μ near the voice coil,
In other words, μ is a magnetic material disposed in the part of the pole piece facing the magnetic gap, and does not increase the impedance in the voice coil, so it sufficiently prevents the decrease in sound pressure level that occurs with an increase in impedance.
Sound pressure frequency characteristics can be improved in the high range.

That is, it is possible to improve the output sound pressure frequency characteristics of the present invention and the conventional example as shown in FIG. 9, which compares each output sound pressure frequency characteristic and each impedance characteristic shown using admittance, which is the reciprocal of impedance.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional internal magnet type magnetic circuit.
Fig. 2 is a sectional view showing the same conventional external magnetic type magnetic circuit, Fig. 3 is a sectional view showing another conventional internal magnetic type magnetic circuit, and Fig. 4 is a sectional view showing still another conventional magnetic circuit. It is a sectional view of a conventional external magnetic type magnetic circuit 'kyFf. FIG. 5 is a cross-sectional view showing an internal magnetic type magnetic circuit according to the present invention, FIG. 6 is a cross-sectional view showing an external magnetic type magnetic circuit according to the present invention, and FIG. 1 is a cross-sectional view showing another embodiment of the present invention. FIG. 8 is a sectional view showing an internal magnetic type magnetic circuit according to an example, and FIG. 8 is a sectional view showing an external magnetic type magnetic circuit according to another embodiment of the present invention. FIG. 9 is a characteristic diagram comparing the present invention and the conventional one. 11... Yoke, 12... Magnet, 13... Pole piece, 14... Plate, 15... Upper end of pole piece.

Claims (1)

[Scope of utility model registration request] A magnetic material that is magnetically saturated with a magnetic flux density lower than the above magnetic flux density is disposed in a portion of the pole piece facing the above air gap that forms a magnetic field with a magnetic flux density of 18,000 Gauss or more in the magnetic air gap. A speaker magnetic circuit in which the magnetic permeability μ is 1 when the material is magnetically saturated.