JPH04324799A - Speaker - Google Patents

Abstract

PURPOSE:To realize the speaker with low magnetic leakage without deterioration in the efficiency inexpensively while employing an auxiliary magnet of an unpolished ferrite with respect to the speaker used for various acoustic equipments and video equipments. CONSTITUTION:A main magnet 28 and an upper plate 27 are arranged on a lower plate 29 and a vibration component comprising a diaphragm 21 and a voice coil 22 is assembled to a magnetic circuit made by bonding the unpolished auxiliary magnet 31 in opposite polarity with the above main magnet 28, at a lower face of the lower plate 29, with a bonding material 30 comprising magnetic powder and binder to obtain the efficient speaker with low magnetic leakage.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art Generally, a speaker is required to have a small leakage magnetic flux. In particular, low magnetic leakage type speakers are desired for color television receivers. Furthermore, with the increasing precision of video equipment such as high-definition, which is expected to become popular in the future, there is a need for even lower magnetic leakage.

[0003] That is, in the above-mentioned video equipment, speakers are generally placed below or on the side of the cathode ray tube;
In such a configuration, if large magnetic leakage occurs from the speaker, the electron beam in the cathode ray tube will be deflected and not converged on one point on the phosphor surface, resulting in a problem of color shift.

[0004] Therefore, many efforts have been made to reduce magnetic leakage, and speakers having the configurations described below are currently in practical use. A speaker using a conventional low magnetic leakage magnetic circuit will be described below with reference to the drawings. FIG. 2 shows a speaker using a conventional low magnetic leakage magnetic circuit. In FIG. 2, 1 is a diaphragm, 2 is a voice coil, 3 is a dust cap, 4 is a damper, 5 is a frame, 6 is a center pole, 7 is a ring-shaped upper plate separated from the center pole 6 by a predetermined distance, 8 is a main magnet, 9 is a lower plate, and 13 is a magnetic gap for inserting the voice coil 2, which is composed of a ring-shaped upper plate 7 separated from the center pole 6 by a predetermined distance. The main magnetic flux a flows. 11 is an auxiliary magnet magnetized with the opposite polarity to the main magnet 8; 12
is the outer edge of the ring-shaped upper plate 7 and the auxiliary magnet 1
The magnetic flux of the auxiliary magnet 11 is connected to the magnetic gap 13 by forming a magnetic circuit with the ring-shaped upper plate 7, center pole 6, and lower plate 9.
The configuration is such that magnetic flux b is guided to.

In the thus constructed low magnetic leakage magnetic circuit, the magnetic flux in the magnetic gap 13 is constituted by the composite magnetic flux of the main magnetic flux a of the main magnet 8 and the magnetic flux b of the auxiliary magnet 11. In addition, both the leakage magnetic flux c due to the main magnet 8 and the leakage magnetic flux d due to the auxiliary magnet 11 are magnetically shielded by the shield cover 12 made of a soft magnetic material without leaking to the outside, so that no magnetic leakage to the outside occurs. can be made sufficiently small. Furthermore, the magnetic flux of the magnetic gap 13 is a composite magnetic flux of the main magnetic flux a caused by the main magnet 8 and the magnetic flux b caused by the auxiliary magnet 11, resulting in an efficient low magnetic circuit.

[0006]

However, the above-mentioned prior art has the following problems.

(1) The auxiliary magnet 11 is also expensive because it uses an expensive magnet that has been polished on both sides after sintering.

(2) When an unpolished magnet manufactured by a wet method after sintering is used, the filter surface that attracts moisture has irregularities, which deteriorates the magnetic efficiency.

The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to improve the efficiency of an inexpensive magnetic circuit of a low-magnetic leakage type speaker, and furthermore, to create a speaker configuration that requires fewer assembly steps. This is what we provide.

0010

[Means for Solving the Problems] In order to achieve this object, the speaker of the present invention uses a sintered, unpolished ferrite magnet as an auxiliary magnet, and has a magnetic permeability for adhesion to the plate and shield cover that constitute the magnetic circuit. It provides a configuration of a magnetic circuit using materials and a binder.

[0011]

[Function] With this configuration, no air gap is created between the unpolished ferrite magnet with an uneven surface and the plate or shield cover that constitutes the magnetic circuit, so the unpolished ferrite magnet after sintering does not reduce magnet efficiency. can be used to realize an inexpensive magnetic circuit.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a speaker showing an embodiment of the present invention.

Details will be explained below based on FIG. 1. 2
1 is a diaphragm, 22 is a voice coil, 23 is a dust cap, 24 is a damper, 25 is a frame, 26 is a center pole, 27 is an upper plate, 28 is a main magnet, 29 is a lower plate, 30 is a joint, 31 is An auxiliary magnet, 32 a shield cover, and 33 a magnetic gap.

The filter surface of the auxiliary magnet 31 of the unpolished ferrite magnet manufactured by the wet method is a joint made of a magnetic powder material (for example, pure iron, permalloy, etc.) with high magnetic permeability and saturation magnetic flux density and a binder (for example, epoxy resin). 30 to the lower plate 29. Furthermore, the auxiliary magnet 31 is magnetized with a polarity opposite to that of the main magnet 28, and its magnetic flux is transmitted between the shield cover 32 joined to the outer edge of the ring-shaped upper plate 27 and the center located at a predetermined distance from the upper plate 27. The magnetic flux of the magnetic gap 33 is guided by the magnetic circuit composed of the pole 26 and the lower plate 29, and becomes a combined magnetic flux with the main magnetic flux of the magnetic circuit composed of the main magnet 28, the upper plate 27, the center pole 26, and the lower plate 29. Configure.

Further, on the opposite side of the ring-shaped upper plate 27 from the magnet adhesively fixed surface, a frame 25 made of iron plate, resin, aluminum die cast, etc. is fixedly bonded and fixed by bonding, welding, screw fixing, or the like. Also, the voice coil 22 has one end inserted into the magnetic gap 33, and the other end has a peripheral edge that is connected to the frame 25.
The diaphragm 21 is fixed to the center of the diaphragm 21 held by the diaphragm 21 . The damper 24 supports the voice coil 22 by adhesively fixing the peripheral portion to the frame 25 and the center portion to the voice coil 22. Furthermore, the leakage magnetic flux due to the main magnet 28 and the leakage magnetic flux due to the auxiliary magnet 31 cancel each other out and do not leak to the outside, and the shield cover 3 is made of a soft magnetic material.
Magnetically shielded by 2.

In the speaker having the configuration shown in FIG. 1, when an audio signal is supplied to the voice coil 22, the voice coil 22 vibrates due to the magnetic flux in the magnetic gap 33, causing the diaphragm 21 to vibrate in accordance with the audio signal. A speaker generates sound according to an audio signal.

The speaker constructed according to the present invention provides an inexpensive, efficient, and economical speaker with low magnetic leakage by bonding the auxiliary magnet 31 of unpolished ferrite with magnetic powder and a binder.

[0018]

As described above, according to the present invention, efficiency can be improved by using an unpolished ferrite magnet, which has the following effects, as an auxiliary magnet, and by joining the unpolished ferrite auxiliary magnet with magnetic powder and a binder. It is possible to produce low-cost, efficient, and economical low-magnetic leakage speakers with high quality without deterioration, and it is compatible with the high precision of video equipment such as high-definition, and it has great industrial effects. It is.

[Brief explanation of drawings]

[Fig. 1] A cross-sectional view of a speaker in an embodiment of the present invention.

[
Figure 2: Cross-sectional view of a conventional speaker

[Explanation of symbols]

21　Diaphragm 22 Voice coil 23 Damper 24 Damper 25 Frame 26 Center pole 27 Upper plate 28 Main magnet 29 Lower plate 30 Joint part 31 Auxiliary magnet 32 Shield cover 33 Magnetic gap

Claims (1)

[Claims] Claim 1: A diaphragm, a voice coil attached to the diaphragm, and a damper that supports the voice coil.
A frame that supports the peripheral edge of the diaphragm at one end, a center pole, a ring-shaped upper plate, a lower plate, a main magnet sandwiched between the upper plate and the lower plate, and a lower part magnetized with a polarity opposite to that of the main magnet. A speaker consisting of a magnetic circuit with a plate, an unpolished auxiliary magnet bonded with powdered magnetic material and a binder, and a shield cover.