JPH0448899A - Speaker - Google Patents

Abstract

PURPOSE:To realize a speaker provided with a magnetic circuit with high size accuracy and high magnetic energy at low cost by coating an outer circumference of an alloy magnet with a resin magnetic layer. CONSTITUTION:A magnetic circuit 5 consists of a yoke 6 formed to be almost cylindrical and made of a magnetic metal, a T shaped pole piece made of a magnetic metal integrated from an open bottom face of the yoke 6, a cylindrical alloy magnet 8 magnetized in the radial direction by sintering or forging integrated to a small diameter part 7a at the upper part of the pole piece 7 and a resin magnetic layer 9 formed so as to cover the circumferential face and the upper face of the alloy magnet 8 and the upper face of the pole piece 7. A magnetic gap 10 is formed between the upper part of the yoke 6 and the resin magnetic layer 9 at the outer circumference of the alloy magnet 8 above the pole piece 7 in the magnetic circuit 5, and the accuracy size of + or -30mum or below for the resin magnetic layer 9 is easily attained.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to speakers used in various types of audio equipment.

2. Description of the Related Art Recently, as a magnetic circuit for a speaker, a structure as shown in FIG. 3 has been developed and is beginning to be used. That is, a pole piece 1 is assembled into a cylindrical yoke 2, a ring-shaped permanent magnet 3 magnetized in the radial direction is installed in the upper part of the pole piece 1, and a magnetic field is created between the permanent magnet 3 and the upper part of the yoke 2. It was configured to form a gap 4.

Problems to be Solved by the Invention In the magnetic circuit having the above configuration, the dimensional accuracy of the magnetic gap 4 is required to be ±30 μm, and in order to maintain this dimensional accuracy, for example, the permanent magnet 3 must have an energy product of 30 meggauss or more. When using neon/iron alloy magnets, the processing cost is extremely high because a ring-shaped permanent magnet is formed by sintering and then polished to an accuracy of about ±20 μm in diameter. It became.

Recently, rare earth magnet powder has been mixed with synthetic resin,
Attempts have also been made to use permanent magnets 3 formed by resin molding, but the dimensional accuracy is sufficiently satisfactory, but even if neon/iron alloy magnet powder, which has the highest energy product, is used, it is less than 10 megauss Oersted. The energy product is , and the magnetic energy is low, making it impractical.

The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide a speaker having a magnetic gap with high dimensional accuracy (and a magnetic circuit with high magnetic flux density) at a low cost.

Means for Solving the Problems In order to solve the above problems, the present invention provides an alloy magnet on the upper part of the pole piece in the yoke, and a resin magnet layer with a thickness of at least 0.5 mm on the surface of the alloy magnet. A diaphragm is incorporated into a frame connected to the magnetic circuit, and a voice coil that fits into the magnetic gap of the magnetic circuit is coupled to the diaphragm.

Effect With the above configuration, sufficient magnetic flux density can be ensured by the alloy magnet, and dimensional accuracy of the magnetic gap can be ensured by the resin magnet layer.

Example Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings, FIG.

This will be explained using FIG.

In FIGS. 1 and 2, 5 is a magnetic circuit, and this magnetic circuit 5 includes a yoke 6 formed of magnetic metal into a substantially cylindrical shape.
A T-shaped pole piece 7 made of magnetic metal is incorporated from the open bottom surface of the yoke 6, and a radially magnetized pole piece formed by sintering or casting is incorporated into the small diameter portion 7a at the top of the pole piece 7. The magnet 8 is made up of a cylindrical alloy magnet 8 and a resin magnet layer 9 formed to cover the curved surface and upper surface of the alloy magnet 8 and the upper surface of the pole piece 7.

The resin magnet layer 9 contains 80 W of neon/iron alloy magnet powder.
It is mixed with synthetic resin so that it is about 100% and then molded to have a thickness of about 1-1% at a thickness of 0.5 m or more. It is largely influenced by the dimensional accuracy of the surface of 8, and is usually preferably about 1 dimensional. The alloy magnet 8 is fixed to the pole piece 7 by press-fitting, bonding, etc., and the pole piece 7 is bonded to the yoke 6 by welding, bonding, etc.

The magnetic circuit 5 having such a configuration includes an upper part of the yoke 6,
A magnetic gap 10 is formed between the alloy magnet 8 on the upper part of the pole piece 7 and the resin magnet layer 9 on the outer periphery.
This means that a dimensional accuracy of ±30 μm or less can be easily achieved with a molding accuracy of .

Further, a frame 11 is coupled to the magnetic circuit 5, and a gasket 12 and a diaphragm 13 are coupled to the periphery of the frame 11 by adhesive or the like. is coupled with a voice coil 14, and the middle part of this voice coil 14 is connected to a damper 15.
The lower part of the voice coil 14 is held in the magnetic gap 10 of the magnetic circuit 5 without eccentricity (fitting into it).

Furthermore, a dust cap 16 is attached to the upper surface of the central portion of the diaphragm 13.

With the above configuration, the alloy magnet 8, which is a high-energy magnet such as sintered or cast alloy magnet, can be used without precision machining, and the outer periphery is provided with a resin magnet layer 9, which makes it easy to achieve dimensional accuracy. , the dimensional accuracy of the magnetic gap 10 is high, and since the base of the permanent magnet is the alloy magnet 8, the magnetic flux density in the magnetic gap 10 can be made equal to that of an alloy magnet whose surface is precisely polished. It can be made highly efficient.

In the above embodiment, a cone-shaped diaphragm 13 is used, but a dome-shaped diaphragm or a flat diaphragm may also be used. It can be applied to any speaker for bass, midrange, or treble.

Effects of the Invention As described above, in the present invention, since the outer periphery of the alloy magnet is covered with a resin magnet layer, a speaker with high dimensional accuracy and a magnetic circuit with high magnetic energy can be provided at low cost. In addition to being able to prevent the magnet from rusting, it also has the advantage of being highly efficient as a speaker, and is of great engineering value.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing an embodiment of the speaker of the present invention;
FIG. 2 is a sectional view of the magnetic circuit of the speaker, and FIG. 3 is a sectional view of the magnetic circuit used in the conventional speaker. 5...Magnetic circuit, 6...Yoke, 7.
...Pole piece, 8...Alloy magnet, 9
... Resin magnet layer, 10 ... Magnetic gap, 11 ... Frame, 13 ... Vibration plate, 14 ... Voice coil.

Claims (1)

[Claims] A magnetic circuit is provided in which an alloy magnet is provided on the upper part of the pole piece in the yoke, and a resin magnet layer with a thickness of at least 0.5 mm is provided on the surface of this alloy magnet. A speaker that incorporates a plate and connects to this diaphragm a voice coil that fits into the magnetic gap of the magnetic circuit.