JP2638201B2 - Low leakage magnetic flux type speaker - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-leakage magnetic flux type speaker used for various audio equipment and video equipment.

2. Description of the Related Art A conventional low-leakage-flux speaker of this type has a configuration as shown in FIG. That is, the diaphragm 6 is adhered to a peripheral portion of a frame 5 formed by integrally molding a magnetic circuit 4 formed by sandwiching the main magnet 1 between an upper plate 2 and a lower plate 3 and molding the same with a resin.
The voice coil 7 for driving the diaphragm 6 is held at the center of the middle part by the damper 8 and is coupled so as to fit into the magnetic gap 9, and is connected to the surface of the coupling portion of the diaphragm 6 with the voice coil 7. The dust cap 10 was adhered to form the speaker body. Further, a cancel magnet 11 magnetized in a direction opposite to that of the main magnet 1 is provided on a back surface of the lower plate 3 and a shield cover 12 which covers the side surface and the back surface of the magnetic circuit 4.

Problems to be Solved by the Invention However, in this kind of conventional low-leakage-flux speaker, the leakage magnetic flux from the magnetic circuit 4 is reduced by the effect of the cancel magnet 11 and the shield cover 12, but in this case, the shield Depending on the shape of the cover 12, it is effective for the speaker magnetic circuit side and back, but
Since there is no component to shield the magnetic flux leakage from the front part of the speaker, a small amount of magnetic flux is generated. Had.

An object of the present invention is to solve such a conventional problem and to provide a low-leakage-flux-type speaker having extremely excellent performance against a leakage magnetic flux.

Means for Solving the Problems In order to solve the above problems, the present invention provides a magnetic metal body and a non-magnetic material on a front surface of an upper plate of a magnetic circuit integrally molded with a resin frame and a front surface of a center pole of a lower plate. A laminated structure consisting of a metal body is bonded with the non-magnetic metal body side as the bonding surface, and this magnetic metal body shields the front of the speaker where a large amount of leakage magnetic flux usually occurs, reducing the leakage magnetic flux to the outside. It was done.

Operation With the above configuration, in addition to the magnetic shielding effect of the conventional cancel magnet and shield cover on the side and back of the speaker magnetic circuit, the front plate and the lower plate of the upper plate are also protected against magnetic flux leakage to the entire surface. The plate is magnetically shielded by a plate made of a magnetic metal body, which is arranged in front of the center pole of the plate and is spaced by a non-magnetic metal body, so that the leakage magnetic flux to the outside is greatly reduced.

Embodiment Hereinafter, a low leakage magnetic flux type speaker according to one embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a magnetic circuit 24 formed by sandwiching a main magnet 21 between an upper plate 22 and a lower plate 23 is integrated with a front surface of an upper plate 22 of a frame 25 formed by molding with resin. The shielding laminated plate 33 made of a magnetic metal body 33b such as iron and a non-magnetic metal body 33a such as aluminum is bonded to the upper plate 22 with the non-magnetic metal body 33a being bonded to the upper plate 22 so that magnetic flux is not directly transmitted from the upper plate 22. Glued as
Similarly, on the front surface of the center pole 23a of the lower plate 23, a shielding laminated plate 34 composed of a magnetic metal body 34b and a non-magnetic metal body 34a is placed on the non-magnetic metal body 34a side so that magnetic flux is not directly transmitted from the center pole 23a. As a bonding surface to the center pole 23a to obtain a housing with low leakage magnetic flux measures. Then, a diaphragm 26 is adhered to the peripheral portion of the frame 25 of the housing, and a voice coil 27 for driving the diaphragm 26 is held at the center of a voice coil 27 by a damper 28 so as to fit into the magnetic gap 29. Combined with the diaphragm
Dust cap on the surface of the joint with 26 voice coil 27
30 is adhered to form a speaker body. Further, a cancel magnet 31 magnetized in a direction opposite to that of the main magnet 21 is provided on a back surface of the lower plate 23, and a shield cover 32 covering side and back surfaces of these magnetic circuits.

In this way, since there is no component to be shielded normally, even in the front direction of the speaker where a large amount of leakage magnetic flux is generated, the nonmagnetic metal body 33a is formed on the front surface of the upper plate 22 and the front surface of the center pole 23a of the lower plate 23. , 34a are magnetically shielded by the shielded laminated plates 33 and 34 composed of magnetic metal bodies 33b and 34b arranged at a distance from each other, and the leakage magnetic flux in the front direction of the speaker is greatly reduced.

Effect of the Invention As described above, the present invention provides the conventional magnetic shield effect of the cancel magnet and the shield cover with respect to the lateral direction and the rear direction of the speaker magnetic circuit, as well as the front direction of the upper plate and the front direction of the center pole of the lower plate. In addition, a magnetic shield in the front direction of the speaker magnetic circuit can be implemented by a shielding laminated plate made of a magnetic metal body placed at a distance by a non-magnetic metal body. it can.

As a secondary effect, a laminated structure composed of a magnetic metal body and a non-magnetic metal body adhered to the center poles of the upper plate and the lower plate can increase the heat capacity due to an increase in the volume of the entire magnetic circuit, and in particular, reduce heat. Since a metal body is added very close to the voice coil, which is the source, the heat dissipation of the voice coil is very good, and the input resistance can be increased.

As described above, the present invention can provide an ultra-low leakage magnetic flux type and high input resistance type speaker, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a low-leakage magnetic flux type speaker according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a conventional low-leakage magnetic flux type speaker. 21: Main magnet, 22: Upper plate, 23: Lower plate, 23a: Center pole, 24: Magnetic circuit, 2
5… frame, 26… diaphragm, 27… voice coil, 2
8 ... Damper, 29 ... Magnetic gap, 30 ... Dust cap, 31 ... Cancel magnet, 32 ... Shield cover, 33 ... Laminated plate for shield, 33a ... Non-magnetic metal body, 33b ... Magnetic metal Body, 34: laminated plate for shield, 34a: non-magnetic metal body, 34b: magnetic metal body.

Claims (1)

(57) [Claims] 1. A housing with a resin frame in which a main magnet is sandwiched between an upper plate and a lower plate, and a magnetic circuit of an external magnet type formed integrally with a frame by a resin, a front portion of the upper plate and a lower plate. A shield plate made of a laminated structure composed of a magnetic metal body and a non-magnetic metal body was bonded to the front surface of the center pole with the non-magnetic metal body side as the bonding surface, and bonded to the frame periphery of the housing with the resin frame. A voice coil that fits into the magnetic gap of the magnetic circuit is coupled to the diaphragm,
A low-leakage magnetic flux type speaker having a cancel magnet adhered to a back surface of the lower plate and a shield cover arranged to cover the magnetic circuit.