JP2603920Y2 - Speaker - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repulsive magnetic field type speaker.

[0002]

2. Description of the Related Art In recent years, a loudspeaker has been required to have higher power. As an effective countermeasure, there is a method of increasing the diameter of a voice coil. In this case, in the conventional outer magnet type, the size of the magnet is correspondingly increased, and from a practical point of view, it is preferable to use the inner magnet type. However, if an inexpensive and commonly used ferrite magnet is used as the inner magnet type, there is a problem of insufficient magnetic flux and insufficient sound pressure. Therefore, by arranging a magnet further on the front surface of the magnetic circuit and adopting a so-called repulsive magnetic field system in which the opposing surfaces have the same polarity, the insufficient magnetic flux can be compensated. However, even in this case, since the magnetic flux loop of the front magnet is opened, not only the magnetic flux cannot be effectively used, but also the magnet is demagnetized at a low temperature. In particular, in a vehicle speaker, a state of about −40 ° C. is assumed in practical use, and demagnetization of 25% or more is expected.

FIG. 2 shows a cross section of a conventional magnetic circuit of the repulsive magnetic field type. The yoke 7 and the middle plate 6 usually use a magnetic material made of iron. As shown in the figure, the flow B of the magnetic flux of the rear magnet 5 passes through the middle plate 6, the yoke 7, and the lower plate 3 to form a closed circuit. On the other hand, the flow A of the magnetic flux of the front magnet 4 passes through the air.

[0004]

However, in the conventional magnetic circuit of the repulsive magnetic field type, the magnetic flux A of the front magnet 4 is
Because it passes through the air, it is not using the magnetic flux effectively,
Also, the permeance is low, and low-temperature demagnetization tends to occur.

The present invention has been devised to solve the above-mentioned problems, and the point is that both of the two opposing magnets can effectively utilize the magnetic flux and have very little low-temperature demagnetization. It is an object to provide a speaker having a circuit.

[0006]

In order to solve the above-mentioned problems, a speaker according to the present invention is arranged such that doughnut-shaped magnets, which are magnetized in the thickness direction, are arranged on the outer periphery of the magnet so that the same poles are opposed to each other. In a speaker provided with a magnetic circuit for generating a repulsive magnetic flux for driving a voice coil, a magnetic flux from a rear magnet 5 is applied to a middle plate 6,
A magnetic circuit is formed so as to pass through one gap 9 provided outside the middle plate 6, the yoke 7 located outside the rear magnet 5 and the gap 9, and the lower plate 3, and the magnetic flux from the front magnet 4 is A magnetic circuit is configured to pass through the middle plate 6, the gap 9, the yoke 7, the lower plate 3, the center pole 2, and the upper plate 1 so that repulsive magnetic fluxes from both magnets can be used effectively. It has features.

[0007]

In order to generate a repulsive magnetic flux for driving the voice coil on the outer periphery of the magnet, the magnetic poles magnetized in the thickness direction of the front and rear donut-shaped magnets are arranged so that the same poles face each other. The magnetic flux from the rear magnet passes through the magnetic circuit of the middle plate, one magnetic gap outside it, the yoke, and the lower plate. The magnetic flux from the front (radiation side) magnet passes through the same middle plate, gap, and lower plate, and further passes through the magnetic circuit of the center pole and upper plate. In this way, the magnetic flux from both magnets passes through the closed inner magnet type magnetic circuit, so that the magnetic flux can be used effectively.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a magnetic circuit according to the present invention. In the figure, a donut-shaped front magnet 4 and a donut-shaped rear magnet 5 are arranged so as to have the same polarity and to face each other. A middle plate 6 constituting a part of a magnetic circuit is provided between the front magnet 4 and the rear magnet 5, and the middle plate 6 and the yoke 7, which is the outer periphery of the magnetic circuit, form the middle plate 6. One gap 9 is provided on the outside to form an inner magnet type magnetic circuit. 1 is an upper plate, 2 is a center pole, and 3 is a lower plate, which constitutes a part of a magnetic circuit. The voice coil 14 is inserted into the gap 9, and the cone paper 11 and the damper 13 are bonded to the voice coil bobbin 15. An edge 12 is adhered to the outer periphery of the cone paper 11.

The repulsive magnetic flux of the magnetic flux flow A from the front magnet 4 and the magnetic flux flow B from the rear magnet 5 pass through the middle plate 6, the gap 9, the yoke 7, and the lower plate 3. The flow B of the magnetic flux from the rear magnet 5 returns from the lower plate 3 to the rear magnet 5. Front magnet 4
The flow A of the magnetic flux further flows from the center pole 2 → the upper plate 1 to the front magnet 4. Since the flows A and B of the magnetic flux both pass through a closed magnetic circuit having good magnetic permeability except for the gap 9, the magnetic flux can be effectively used, and low-temperature demagnetization hardly occurs.

The calculation results of the permeance coefficient of the magnet by the finite element method are as follows. Magnet size: outer diameter = 75mm, inner diameter = 32mm, height = 1
0 mm magnet material: In the case of strontium ferrite, the permeance coefficient of the front magnet is 0.61 in FIG. 2 of the conventional example, and at −40 ° C., the permeance coefficient of the front magnet becomes the knick point (the bending point of the BH curve). ) Is lower than the permeance coefficient = 1.22, and low-temperature demagnetization occurs. On the other hand, the permeance coefficient of the front magnet in FIG. 1 according to the present invention is greatly improved to 1.42, and even at −40 ° C., the low temperature demagnetization of the front magnet does not occur.

[0011]

As described above, the loudspeaker according to the present invention has the front and rear donut-shaped magnets magnetized in the thickness direction arranged so that the same poles are opposed to each other. In a speaker provided with a magnetic circuit for generating repulsive magnetic flux, a rear magnet 5
A magnetic circuit is formed so that the magnetic flux from the motor passes through the middle plate 6, a gap 9 provided outside the middle plate 6, the yoke 7 located outside the rear magnet 5 and the gap 9, and the lower plate 3. A magnetic circuit is formed so that the magnetic flux from the front magnet 4 passes through the middle plate 6, the gap 9, the yoke 7, the lower plate 3, the center pole 2, and the upper plate 1. Can be used effectively,
The magnetic flux can be used effectively, and the low-temperature demagnetization can be extremely reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a section of a magnetic circuit of a speaker according to the present invention.

FIG. 2 is a cross-sectional view showing a cross section of a repulsive magnetic field type magnetic circuit of a conventional speaker.

[Explanation of symbols]

 Reference Signs List 1 upper plate 2 center plate 3 lower plate 4 front magnet 5 rear magnet 6 middle plate 7 yoke 9 gap 11 cone paper 12 edge 13 damper 14 voice coil 15 voice coil bobbin

Claims (1)

(57) [Scope of request for utility model registration] 1. A speaker provided with a magnetic circuit for generating a repulsive magnetic flux for driving a voice coil on the outer periphery of a magnet, wherein a donut-shaped magnet on the front surface and a donut magnet on the rear surface magnetized in the thickness direction are arranged so that the same poles face each other. The magnetic flux from the rear magnet (5) is applied to the middle plate (6), a gap (9) provided outside the middle plate (6), and the gap (9) with the rear magnet (5).
Yoke (7) and lower plate (3) located outside
The magnetic flux from the front magnet (4) passes through the middle plate (6), the gap (9), the yoke (7), the lower plate (3), and the center pole (2). A speaker comprising a magnetic circuit configured to pass through the upper plate (1) so that repulsive magnetic flux from both magnets can be used effectively.