JPH06163240A - Magnet system for electroacoustic transducer - Google Patents

Abstract

PURPOSE: To provide a magnetic system which enables a significant increase of the flux density of a gap. CONSTITUTION: An electric acoustic converter magnetic system, whose core 12 has a neodymium disc 14, has been known by its prior art. In order to increase the flux density of a gap 17, it has been known in the prior art that the weight of the neodymium disc 14 of the core 12 is increased. However, the flux density is increased only by 5-8% of the initial density by this method. By attaching another neodymium disc 18 to the side of a bottom 16 of the cup-type magnet 11 which is opposite to the side to which the disc 14 is attached, the problem is solved. In accordance with the significant increase of the flux density of the gap 17 which is obtained with the present invention, the quantity of the neodymium material used can be minimized, regardless of attaching of the two neodymium discs 14 and 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet system for an electroacoustic transducer in which the magnetic flux density in the gap is increased and the system structure is miniaturized.

[0002]

2. Description of the Related Art A magnet system of an electroacoustic transducer is generally constructed by inserting a magnetic core into a cup-shaped magnet centering on the central axis of the system. The free end of the core, which is not connected to the bottom of the cup magnet, is connected to a so-called pole plate. The pole plate has a larger diameter than the magnetic core. Depending on the dimensions of the cup-shaped magnet, the upper edge of the cup-shaped magnet is joined to the disc that projects into the cup-shaped magnet or is integrally formed as described above. The edge area of the magnetic pole plate parallel to the central axis and the edge area of the member projecting inside the cup-shaped magnet face each other at a distance,
In this way, a system gap is formed.

Conventionally, such magnet systems are usually made of ferrite materials. In a structure made of ferrite material, in order to obtain a sufficiently high magnetic flux density in the gap, it is necessary to make the magnet system larger and therefore heavier than the remaining weight of the loudspeaker structure.

It is also known to make magnetic cores from the material known under the name Neodymium in the field of transducer technology.
The use of this magnetic high-energy material makes the transducer made by the neodymium method much smaller than the transducer made by the ferrite method when compared with the transducer made by the ferrite method. There is an advantage that can be. Another consequence of the miniaturization possible with neodymium type transducers is the reduction in weight of the magnet system.

However, the advantage associated with the use of neodymium as the core material is that the magnetic flux density in the gap is arbitrarily increased by simply increasing the size of the core portion of neodymium starting from a given size of neodymium core. You should not understand that you can. Rather, when neodymium is used as the material for the part of the magnetic core, the increase in the magnetic flux density obtained as the weight of the neodymium part increases increases only incomparably little. To explain this as an example, let's touch on the following. That is, the magnetic flux density (BL) of about 0.6 Tesla is obtained in the gap with the weight x of the neodymium portion of the magnetic core, but even if the weight of the neodymium portion of the magnetic core is increased to 2x, the magnetic flux density obtained in the gap is approximately 0, It can only increase to 645 Tesla.

[0006]

Therefore, the underlying problem of the present invention is to provide a neodymium magnetic core type magnet system in which the obtained gap magnetic flux density is higher than that of the known structure.

[0007]

This problem is solved according to claim 1 by disposing another neodymium disc on the side of the pole plate opposite to the cup-shaped magnet bottom. The gap magnetic flux density obtained by this arrangement is 5 compared with the conventional structure.
It is possible to increase it to 0%.

Further, it is possible to reduce the weight of the entire magnet system based on the increase in the magnetic flux density obtained by this arrangement. For example, if a magnetic flux density of 0.65 Tesla is required for the gap, and if a neodymium disc with a weight of 2x is used for the magnetic core, therefore, the weight of the neodymium disc of the magnetic core is 0.
Similar gap flux densities can be obtained by reducing this to 6x and combining this configuration with another neodymium disc weighing about 0.6x placed on the pole plate.

If the two neodymium discs have the same diameter according to the second aspect, a particularly uniform course of the magnetic field lines is obtained in the gap. This has the advantage that the heavier weight neodymium disc of the two can be arranged on the pole plate, since the weights of the two neodymium discs according to claim 3 do not necessarily have to be equal. As a result, the overall height of the magnet system between the bottom and the top edge of the pole plate or cup magnet can be reduced. Since it is possible to arrange neodymium discs of different sizes or weights on both sides of the magnetic pole plate, the magnetic flux density required for the gap can be extremely simplified by simply changing the weight of one of the two neodymium discs. Can be adjusted to. As a result, in particular, a unit consisting of the first neodymium disc of the magnetic pole plate and the cup-shaped magnet is pre-manufactured for a large number of loudspeakers, and another neodymium disc is attached to the loudspeaker of various models. It is possible to adjust the required magnetic flux density.

[0010]

The present invention will be described in detail with reference to the drawings. Figure 1
Shows a magnet system 10 for an electroacoustic transducer. The magnet system 10 substantially includes a cup-shaped magnet 11 and a magnetic core 12. The upper edge of the cup-shaped magnet 10 has a circumferential unshaped flange 13 that faces the central axis of the system. The magnetic core 12 is composed of a circular magnetic pole plate 15 similar to the disc 14 made of neodymium, and the upper end of the neodymium disc 14 is joined to the magnetic pole plate 15. Since the diameter of the magnetic pole plate 15 is selected to be larger than the diameter of the neodymium disc 14, the upper edge of the magnetic core 12 is also formed in a flange shape. The end of the magnetic core 12 on the opposite side of the magnetic pole plate 15 is arranged and coupled on the bottom 16 of the cup-shaped magnet 11 about the central axis. Cup magnet 11
And the height of the magnetic core 12 coupled to the bottom 16 are equal, and the outer diameter of the pole plate 15 is smaller than the inner diameter of the flange 13, so that the gap 17 of the magnet system 10 is formed between the flange 13 and the pole plate 15. To be done. A voice coil (not shown) is then inserted into this gap 17 to complete the electromagnetic transducer. Another neodymium disk 18 is also arranged and coupled on the opposite side of the pole plate 15 from the first neodymium disk 14, again centering on the central axis.
Eight like poles (two north poles in this case, N / N) are directly opposed, separated only by pole plate 15. The diameter of the other neodymium disc 18 is equal to the diameter of the neodymium disc 14 arranged in the magnetic core 12. This equal diameter of the two neodymium disks 14, 18 ensures that the course of the magnetic field lines of the gap 17 has a particularly uniform course.

In order to explain that an increase in magnetic flux density can be obtained by arranging another neodymium disk 18 in this way, the following will be touched upon. Another Neodymium disk 18
It is assumed that a magnetic flux density of, for example, 0,6 Tesla is obtained by the configuration of FIG. 1 excluding only the above, and the weight of the neodymium disk 14 in the magnetic core 12 is changed to another neodymium disk 18 to increase the magnetic flux density of the gap 17. If the weight is increased by the weight of, the cup-shaped magnet 11 becomes larger accordingly, and only a 5 to 8% increase in the magnetic flux density can be obtained. However, with the structure shown in FIG. 1, the gap 1 is smaller than that of the magnet system 10 having only the neodymium disk 14 in the magnetic core.
An increase in magnetic flux density of 7 up to 50% can be obtained.
The advantages obtained with the provision of another neodymium disc 18 according to the invention can also be used to minimize the amount of neodymium used. That is, if a predetermined magnetic flux density is required in the gap 17, and this magnetic flux density can be obtained by the neodymium disk 14 having a weight of 2x arranged in the magnetic core 12, two neodymium disks having a total weight of 1,2x are obtained. Disks 14, 18
Can be used to divide this weight into two neodymium disks 14, 18 on either side of the pole plate 15 to achieve the same magnetic flux density. A further weight saving is obtained by using two neodymium discs 14, 18 on either side of the pole plate 15 because of the weight of the first neodymium disc 14 disposed in the pole plate 12. This is because the structure of the cup-shaped magnet 11 can be reduced due to the reduction.

As shown in FIGS. 2A and 2B, it is not necessary to select the two neodymium discs 14 and 18 on both sides of the pole plate 15 so as to have the same weight and structure. Rather, unlike the schematic diagram of FIG. 1, the neodymium disc 14 disposed on the pole plate 15 can be made smaller or larger than another neodymium disc 18. Since such a combination is possible, the cup-shaped magnet 11 and the magnetic core 12 are pre-manufactured for many types of loudspeakers, and different neodymium discs 18 of various sizes are arranged on the pole plate 15. Thus, the final adjustment of the magnetic flux density of the gap 17 required for different models can be performed.

[Brief description of drawings]

FIG. 1 is a side view of a magnet system of an electroacoustic transducer.

FIG. 2 is a side view of another magnet system including (A) and (B).

[Explanation of symbols]

14 ... Neodymium disc, 15 ... Magnetic pole plate, 17 ... Gap,
18 ... Another Neodymium disc.

Claims (3)

[Claims] 1. A cup-shaped magnet and a neodymium disc (14).
To increase the magnetic flux density of the gap (17) in a magnet system for an electroacoustic transducer comprising a magnetic core which is composed of a magnetic pole plate and a magnetic pole plate and is coupled to the bottom of the cup-shaped magnet around the central axis of the loudspeaker. And the neodymium disc (1) of the pole plate (15)
A magnet system characterized in that another neodymium disc (18) is arranged on the side opposite to 4). 2. Magnet according to claim 1, characterized in that the diameter of the further neodymium disc (18) corresponds to the diameter of the neodymium disc (14) arranged in the magnetic core (12). system. 3. Magnet system according to claim 1 or 2, characterized in that the dimensions of the first neodymium disc (14) differ from the dimensions of another neodymium disc (18).