JPH0530593A - Speaker - Google Patents

Abstract

PURPOSE:To provide a speaker to be used for various acoustic apparatuses and video apparatuses with excellent characteristic relating to leakage magnetic flux by reducing magnetic flux to be leaked from the center pole of the speaker to the front direction of the speaker. CONSTITUTION:In order to reduce leakage magnetic flux generated from the upper face of the center pole of a lower plate 3 to the front direction of the speaker, a bobbin 13 to be used for a voice coil 14 is constituted of a magnetic metal or a material obtained by containing magnetic material powder in paper or resin and provided with a magnetism shielding effect, so that leakage magnetic flux from the center pole of the lower plate 3 is converged into the bobbin 13 and magnetic flux to be leaked to the external is sharply reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker used in various audio equipment and video equipment.

[0002]

2. Description of the Related Art A conventional speaker will be described below with reference to the drawings. FIG. 2 is a cross-sectional view showing the structure of a conventional speaker, in which a main magnet 1 is sandwiched between an upper plate 2 and a lower plate 3 having a center pole, and a magnetic circuit 5 is formed integrally with a frame 4 and molded with resin. The voice coil 7 is molded, the voice coil 7 is fixed to the peripheral portion of the frame 4, and the peripheral portion of the diaphragm 8 is fixed to the peripheral portion of the frame 4. The voice coil 7 is fitted into the magnetic gap 9 formed in the magnetic circuit 5, An inner peripheral portion of a damper 6 whose peripheral portion is coupled to the frame 4 is coupled to and supported by an intermediate portion of the coil 7, and a dust cap 10 is fixed so as to cover a coupling portion between the diaphragm 8 and the voice coil 7. Was configured.

Further, an auxiliary magnet 11 magnetized in the opposite direction to the main magnet 1 and a shield cover 12 formed so as to cover the entire magnetic circuit 5 are coupled to the lower surface of the lower plate 3 to form a magnetic circuit. The magnetic flux leaking from No. 5 was configured to be blocked as much as possible.

[0004]

However, in the above conventional structure, the auxiliary magnet 11 and the shield cover 12 are provided.
Although the magnetic flux leaking to the lower surface and the side surface of the magnetic circuit 5 can be reduced by the effect of, the magnetic flux leaking from the center pole of the lower plate 3 to the upper surface of the magnetic circuit 5, that is, the entire surface of the speaker can be blocked. Instead, the magnetic flux leaks. For this reason, in the field of video where the leakage magnetic flux is extremely severe, there is a problem that it may not be usable due to the leakage magnetic flux to the front surface of the speaker.

The present invention solves these conventional problems,
It is an object of the present invention to provide a speaker with extremely little leakage magnetic flux.

[0006]

In order to solve the above-mentioned problems, the speaker according to the present invention has an integrated structure of a magnetic circuit in which a main magnet is sandwiched between an upper plate and a lower plate having an auxiliary magnet connected to the lower surface to form a magnetic gap. A voice coil formed by winding a coil around a bobbin made of paper or resin containing magnetic metal or powder of magnetic material in the center of the resin frame molded into Is fitted in the gap, and a shield cover formed so as to cover the magnetic circuit is coupled to the bottom of the frame.

[0007]

With this structure, in addition to the magnetic shield effect of the auxiliary magnet and the shield cover, the leakage flux toward the front of the speaker generated from the center pole of the lower plate is magnetically shielded by the voice coil bobbin made of magnetic metal. Therefore, the leakage magnetic flux can be significantly reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A speaker according to an embodiment of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the components having the same configurations as those of the conventional example.

FIG. 1 is a cross-sectional view showing the structure of a speaker according to the present invention. A magnetic circuit 5 constituted by sandwiching a main magnet 1 between an upper plate 2 and a lower plate 3 having a center pole is integrated with a frame 4. Are molded with resin.

A peripheral portion of the diaphragm 8 is formed by connecting a voice coil 14 formed by winding a coil around a bobbin 13 made of paper or resin containing magnetic metal or powder of magnetic material to the peripheral portion of the frame 4. And the voice coil 14 is fitted in the magnetic gap 9 formed in the magnetic circuit 5, and the inner peripheral portion of the damper 6 whose peripheral portion is coupled to the frame 4 is coupled to and supported by the intermediate portion of the voice coil 14. The dust cap 10 is fixed so as to cover the connecting portion between the diaphragm 8 and the voice coil 14.

Further, an auxiliary magnet 11 magnetized in the opposite direction of the main magnet 1 and a shield cover 12 formed so as to cover the entire magnetic circuit 5 are connected to the lower surface of the lower plate 3 to form a magnetic circuit. The magnetic flux leaking from No. 5 is configured to be blocked as much as possible.

In the voice coil 14, since the bobbin 13 around which the coil is wound is made of paper or resin containing magnetic metal or powder of magnetic material, the speaker is viewed from the upper surface of the center pole of the lower plate 3 of the magnetic circuit 5. The magnetic flux leaking in the front direction of the is focused by the bobbin 13,
The magnetic circuit 5 is efficiently guided by the upper plate 2.

As a result, the bobbin 13 magnetically shields the magnetic flux leaking from the upper surface of the center pole toward the front surface of the speaker, and the leakage magnetic flux can be reduced by about 20 to 30% as compared with the conventional product.

The material used for the bobbin 13 may be a magnetic metal formed by molding an iron plate, for example, in addition to paper and resin containing magnetic material powder. However, when a conductive material is used as the material of the bobbin 13, it is necessary to wind the coil around the surface of the bobbin 13 via an insulator.

[0015]

As described above, in the speaker according to the present invention, the auxiliary magnet and the shield cover prevent the magnetic flux leaking to the lower surface and the side surface of the magnetic circuit, and by using the voice coil using the bobbin having the magnetic shield effect. The magnetic flux leaking from the center pole toward the front of the speaker can be reduced, and the magnetic flux leaking to the outside can be comprehensively reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a speaker according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of a conventional speaker.

[Explanation of symbols]

 1 Main Magnet 2 Upper Plate 3 Lower Plate 4 Frame 5 Magnetic Circuit 6 Damper 8 Vibration Plate 9 Magnetic Gap 10 Dust Cap 11 Auxiliary Magnet 12 Shield Cover 13 Bobbin 14 Voice Coil

Claims (1)

Claim: What is claimed is: 1. A resin frame formed by integrally molding a magnetic circuit in which a main magnet is sandwiched by an upper plate and a lower plate having an auxiliary magnet connected to the lower surface to form a magnetic gap. A bobbin made of paper or resin containing magnetic material powder is wound around the coil, and the voice coil is attached to the center of the diaphragm.The voice coil is fitted into the magnetic gap, and the bottom of the frame is attached. A speaker in which a shield cover is formed so as to cover the magnetic circuit.