JPS5855732Y2 - magnetic circuit - Google Patents

Description

[Detailed description of the invention] The present invention relates to a magnetic circuit used in a ribbon type speaker, etc.
It is an object of the present invention to provide a magnetic circuit that can obtain approximately the same magnetic flux density with a smaller number of magnets than a conventional so-called push-pull type magnetic circuit.

A conventional single-type magnetic circuit used as a magnetic circuit for a Novon type speaker has a structure in which a magnet 3 is disposed only on one side of a membrane diaphragm 2 provided with a voice coil 1, as shown in FIGS. 1A and 1B. A current corresponding to the audio signal is passed through the voice coil 1 to cause the membrane diaphragm 2 to vibrate according to Fleming's left-hand rule, thereby producing sound.

However, in this case, since the magnet 3 is provided only on one side of the diaphragm 2, the magnetic flux 3' from the magnet 3 concentrates on the coil 1 provided in the magnetic gap, and the frequency As shown in curve 1 in Figure 2, the pressure characteristics range from 85 dB to 88 dB.
It had the disadvantage of being inefficient, as it could only obtain a value of about dB.

Therefore, the conventional push-pull magnetic circuit as an improved version has magnets 3a on both sides of the diaphragm 2, as shown in FIG.
3b are arranged so that the magnetic pole faces of the same sex are opposed to each other.

This thing has magnetic fluxes 3a', 3 due to magnets 3a, 3b.
Since b' is concentrated in coil 1, it is possible to obtain better frequency characteristics than those shown in Fig. 1 A and B, but it has the disadvantage that it requires a large number of magnets and cannot be constructed lightweight and inexpensively. .

The present invention eliminates the above-mentioned drawbacks, and one embodiment thereof will be described with reference to FIG. 4 and the following figures.

FIG. 4 shows a schematic diagram of an embodiment of the magnetic circuit according to the present invention, and the same components as those in FIGS. 1A and 1B are given the same numbers.

In the same figure, the magnet 3 is a magnetic pole S, the magnet 32 is a magnetic pole N,
The magnets 33 are arranged in parallel to the yoke 4 so that their magnetic poles S face the diaphragm 2.

On the other hand, the magnet 5 is fixed to the yoke 6 at a position facing the central magnet 32 with the diaphragm 2 in between, with the magnetic pole faces of the same sex as the magnet 3□ facing each other.

With this configuration, the magnetic flux 3□ from the N pole of the magnetic pole 3□
' reaches the south pole of magnets 30, 33, while the magnetic flux 5' from the north pole of magnet 5 reaches the south pole of magnets 3□, 33, and the magnetic flux 32
' does not leak upward in the figure due to the magnetic flux 5'.

As a result, magnetic flux is more easily concentrated in the coil 1 than in the conventional ones shown in Fig. 1A and B, and its frequency vs. sound pressure characteristics are second to none.
As shown by curve II in the figure, a value of about 87 dA to 93 dB can be obtained.

Moreover, the magnetic flux 5' is connected to the magnets 3i and 3a without leaking to the outside.
To reach this, between magnets 5, 3□ and magnets 3 and 9, magnets 5,
The magnetic flux density in the magnetic air gap between 3□ and the magnet 33 can be obtained to be approximately the same as that of the conventional push-pull type magnetic circuit shown in FIG. Moreover, it can be constructed with fewer magnets than this one, and can be constructed lightweight and inexpensively.

FIG. 5 shows a schematic diagram of another embodiment of the circuit of the present invention;
In the figures, the same components are given the same numbers.

This device has coils 7 arranged in three magnetic gaps, with magnets 3. ．． 33 is an S pole, and magnets 32 and 34 are N poles.
The magnets 51 and 5□ and the magnet 5□ and 3□, respectively, are provided so that their poles face the diaphragm 2, and the magnetic pole faces of the same sex face each other.

This also makes it easier for magnetic flux to concentrate on the coil 7 compared to a single type magnetic circuit, and is lighter and cheaper than a push-pull type magnetic circuit in which the same number of magnets are arranged on both sides of the diaphragm. Can be configured.

FIG. 6 shows a schematic diagram of yet another embodiment of the circuit of the present invention.

This device has coils 8 disposed in four magnetic gaps, and since it can be more easily understood than the embodiment shown in FIGS. 4 and 5, the explanation thereof will be omitted.

As described above, the magnetic circuit according to the present invention includes a plurality of first magnets arranged in parallel in a plane, excluding the magnets at the ends, with magnetic poles of the same sex as those of the first magnets facing each other, and a second magnet. Because the magnet is provided, it is easier to concentrate magnetic flux in the magnetic gap than in a conventional single-type magnetic circuit, and as a result, it is possible to obtain a higher sound pressure than in a conventional single-type magnetic circuit.
Unlike conventional push-pull type magnetic circuits, the second magnet is not arranged for all the first magnets, so it can be configured with fewer magnets than this one, making it lighter and cheaper. Furthermore, since almost no magnetic flux leaks to the outside, the magnetic flux density in the magnetic air gap can be obtained to be approximately the same as that of a conventional push-pull type magnetic circuit, and approximately the same level of sound pressure can be obtained. It has features such as being able to

[Brief explanation of the drawing]

1A and 1B are schematic front views and schematic perspective views of an example of a conventional single-type magnetic circuit, respectively, and FIG. 2 is a ribbon illustrating the conventional magnetic circuit shown in FIGS. Figure 3 is a schematic front view of an example of a conventional push-pull type magnetic circuit, and Figures 4 to 6 are examples of the magnetic circuit according to the present invention. FIG. 1.7.8...Voice coil, 2...
Membrane diaphragm, 3, ~3. ,5,5. ~53...
Magnet, 32', 5'...Magnetic flux, 4,6...
··yoke.

Claims (1)

[Scope of utility model registration request] A plurality of first magnets are arranged side by side in a plane with their magnetic pole faces perpendicular to the plane with a magnetic gap between them, and a second magnet is arranged in a direction perpendicular to the plane with a magnetic gap between them and the first magnets. In a magnetic circuit in which magnetic poles of the same sex as the magnetic poles of the first magnet are arranged to face each other, the second magnet is attached to the plurality of first magnets excluding the magnet at the end. A magnetic circuit formed by arranging them facing each other.