JPH02281900A - Magnetic circuit for loudspeaker - Google Patents

Abstract

PURPOSE:To strengthen magnetic energy by bending vertically the inside diameter part of the upper plate toward the bottom part plate side, providing a notch part to which a bend part is fitted on the upper part of the inside diameter part of a magnet, and extending the inside diameter part except the notch part to the middle part of material thickness of the bend part of the upper plate. CONSTITUTION:A bend part 4 is formed by bending vertically the inside diameter part of the upper plate 3 toward the bottom part plate 1 side, and on the upper part of the inside diameter part of a magnet 2, a notch part 5 to which the bend part 4 is fitted is provided. Subsequently, a magnetic circuit is constituted by extending the inside diameter part except the notch part 5 of the magnet 2 to the middle part of material thickness of the bend part 4 of the upper plate 3. The inside diameter part of the magnet 2 extended to the middle part of material thickness of the bend part 4 of the upper plate prevents an increase of a leakage flux caused by a fact that the bend part 4 and the bottom part plate 1 are brought close to each other, and simultaneously, increases volume of the magnet 2. In such a way, the magnetic energy can be strengthened efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic circuit for a speaker that constitutes a speaker used in various types of acoustic equipment.

Conventional technology Conventionally, in an external magnetic type magnetic circuit that constitutes a speaker,
There is a technique in which the inner diameter of the top plate is bent at right angles toward the bottom plate.

This is shown in Figure 2.

Here, 21 is the bottom plate, 22 is the magnet, 23
is an upper plate with a bent portion 24.

This is 1. compared to the material thickness of the upper plate 23. Bending part 2
4 makes the facing magnetic pole part thicker, thereby widening the magnetic field range without increasing the thickness of the magnetic circuit, and also reducing the material cost of the upper plate 23.

Problems to be Solved by the Invention However, in the above conventional example, the upper plate 2
There was a problem in that leakage magnetic flux increased because the lower end of the bent portion 24 of No. 3 approached the bottom plate 21.

Furthermore, the inner diameter of the magnet 22 is restricted by the material thickness of the bent portion 24, which is a factor that further reduces magnetic energy.

An object of the present invention is to solve the above-mentioned conventional problems and provide a magnetic circuit for a speaker that has a wide magnetic field range without increasing the thickness of the magnetic circuit and has strong magnetic energy. It is something to do.

Means for Solving the Problems In order to solve the above problems, the present invention bends the inner diameter part of the top plate at right angles toward the bottom plate side, and provides a notch part in which the bent part is fitted into the upper part of the inner diameter part of the magnet. In addition, the inner diameter portion of the magnet other than the cutout portion is extended halfway through the material thickness of the bent portion of the upper plate.

Effect: According to the above means, the inner diameter part of the magnet, which extends halfway through the thickness of the bent part of the top plate, prevents an increase in leakage magnetic flux due to the approach of the bent part and the bottom plate, and at the same time reduces the volume of the magnet. It is something that can increase the magnetic energy and make it more powerful.

Embodiment FIG. 1 shows an embodiment of a magnetic circuit for a speaker according to the present invention. Here, 1 is a bottom plate having a center pole 1a, 2 is a ring-shaped magnet, and 3 is a bent part 4.
It is an attached upper plate.

The plate shape is the same as that of the conventional example, but the magnet 2, which has a notch 5 in the upper part of the inner diameter part into which the bent part 4 of the upper plate 3 is fitted, and the upper plate 3 with the bent part 4 are assembled together. These points are the features of the present invention.

In the conventional example shown in FIG. 2, by bending the top plate, the distance from the bottom plate becomes closer at the inner diameter, increasing leakage magnetic flux, but in the embodiment shown in FIG. Since the magnet 2 is present between the bottom plate 1 and the polarity opposite to the leakage magnetic flux, leakage is suppressed to an extremely low level.

Furthermore, in the conventional example, the inner diameter of the magnet is limited by the outer diameter φ of the bent part, which is disadvantageous in terms of volume compared to a case without a bent part, but in the embodiment shown in FIG. The volume can be increased by the inner diameter portion of the magnet 2 that extends and protrudes.

However, the innermost diameter of the magnet 2 must be smaller than the inner diameter φB of the bent portion 4 of the upper plate 3, and the magnet 2
It is necessary to provide a radius at some corners C, C2 of the notch 6.

The former is a measure against a gap failure per voice coil, and the latter is a measure against a foreign object failure due to a chip in the magnet 2.

In addition, according to the study results in this example, when the diameter of the center pole 12L of the bottom plate 1 is φ25, the optimum value was obtained in the following setting range.

The material thickness of the upper plate 3 is 3 to 6 m shoulder, the thickness of the upper plate material + 1 to 3 mm in the opposing magnetic poles of the bent part 4, and the inner diameter of the cutout part 5 of the φ person and the lower end of the bent part 4 and the magnet 2. The gap W□, HA is 0.5 to 2 mm, and the distance WB between φB and the innermost diameter of the magnet is o to 4 mytt.
C,, R in G2 is Ro, 5~R2 shoulder shoulder.

Effects of the Invention As described above, the present invention has a structure in which the inner diameter part of the top plate is bent at right angles toward the bottom plate side to form a bent part, and the notch part is fitted into the upper part of the inner diameter part of the magnet. The following effects can be obtained by providing a magnetic circuit and configuring a magnetic circuit by extending the inner diameter part of the magnet other than the cutout part to the middle of the thickness of the bent part of the upper plate.

(1) In a magnetic circuit using a conventional upper plate with a bent portion, magnetic energy can be efficiently increased without losing its effect.

(2) It can be implemented with only a slight increase in materials and has great cost benefits.

(3) It can be produced using exactly the same process as conventional methods, and has great feasibility.

As described above, the present invention has high practicality including mass production,
It's valuable.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a magnetic circuit for a speaker according to an embodiment of the present invention, and FIG. 2 is a sectional view of a magnetic circuit for a speaker according to a conventional example. 1...Bottom plate, 1a...Center pole, 2...Magnet, 3...Top plate, 4...Bent part, 5... ...Notch.

Claims (1)

[Claims] It is composed of an upper plate and a bottom plate with a center pole that sandwich a magnet, the inner diameter part of the upper plate is bent at a right angle toward the bottom plate side, and a notch part is provided in the upper part of the inner diameter part of the magnet to fit the bent part, A magnetic circuit for a speaker is formed by extending the inner diameter part of the magnet other than the notch part to the middle of the material thickness of the bent part of the upper plate.