JPS63224593A - Dynamic speaker - Google Patents

Abstract

PURPOSE:To enhance the economy by fitting a cap made of a magnetic material to at least one of the magnetic gap constitution part. CONSTITUTION:A magnet 2 and a yoke 3 are bonded to a yoke 1 to bond a pole piece 4 to the magnet 2 and to constitute the magnetic gap 5. A cap 7 pressed as a cap shape made of a material where a nonmagnetic metal 7b such as copper, aluminum is clad to a magnetic substance 7a made of iron or the like by a thickness of 50-100mu is fitted. Thus, the thickness of the nonmagnetic part is minimized and the magnetic flux density of the gap 5 so as to enhance the economy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrodynamic speaker used in audio products.

Conventional technology A conventional internal magnetic type magnetic circuit is shown in FIG.

That is, the magnet 2 is joined to the yoke 1, and the upper yoke 3 is joined to the yoke 1. On the other hand, the pole piece 4 is joined on top of the magnet 2, and the pole piece 4 and the yoke 3 are connected.
A magnetic gap 6 of uniform width is formed between the two.

Here, the pole piece 41 upper yoke 3 is made of a magnetic material such as iron. An electrodynamic speaker is constructed by placing a voice coil in this magnetic gap 6, but ideally this voice coil should receive a force from the magnetic circuit that is directly proportional to the current flowing through the voice coil. be. However, in reality, the current flowing through the voice coil generates magnetic flux, which changes the magnetic flux density in the magnetic gap, and the force acting on the voice coil is no longer directly proportional to the current flowing through the voice coil. This phenomenon causes distortion in the sound produced by the speaker, which is called current distortion.

Figure 4 shows one of the methods conventionally used to reduce this current distortion.
A cap 6 made of copper or aluminum is attached. By doing this, a current flows through the cap 6 so as to cancel the magnetic flux generated by the voice coil, and a change in the magnetic flux density in the magnetic gap 6 is reduced, so that a magnetic circuit with small current distortion can be obtained.

Problems to be Solved by the Invention However, in the conventional method, a non-magnetic material such as copper or aluminum is replaced with a magnetic material in the 2Mi magnetic gap, so when viewed as a magnetic circuit, the gap width of the magnetic gap portion becomes wider by the thickness of the non-magnetic material, and there is a problem that the magnetic resistance in this part increases and the magnetic flux density decreases.

Regarding the thickness of the non-magnetic material, it has been experimentally reported that the thickness of the non-magnetic material is approximately 50μ to 100μ in order to reduce current distortion, but in reality, machining of the cap shape etc. Due to this difficulty, a thickness of about 300μ to 500μ is adopted, which lowers the magnetic circuit performance more than necessary.

The present invention aims to provide an electrodynamic speaker that can solve this problem.

Means for Solving the Problems The present invention provides an electrodynamic speaker in which a voice coil is disposed in a magnetic gap formed by a pole piece and a yoke, in which at least one of the magnetic gap components of the pole piece and the yoke is A cap made of magnetic material is bonded to the cap.

Effect: With the above configuration, the thickness of the non-magnetic portion can be set to the required minimum thickness, so the magnetic flux density of the magnetic gap can be increased.

Embodiment FIG. 1 shows a first embodiment of the present invention. That is, the magnet 2 is connected to the yoke 1, and the upper yoke 3 is connected to the yoke 1.
A pole piece 4 is joined onto the magnet 2, and a magnetic gap 6 is formed between the pole piece 4 and the upper yoke 3. At this time, a material 7 formed by press-molding a material made of a steel plate 71L clad with a copper plate 7b into a cap shape is attached to the magnetic gap forming portion at the tip of the pole piece 4.

FIG. 2 shows a second embodiment of the present invention, in which a material 7 press-formed into a cap shape is used as an upper yoke 3 in contrast to the first embodiment.
It is attached to the magnetic gap component of the

As in the above embodiment, the thickness of the copper plate 7b attached to the pole piece 4 or the upper yoke 3 may be 60μ to 100μ in practice, so in this embodiment, the magnetic material 7a such as iron is replaced with a conductive material such as copper or aluminum. Caps and rings are formed using cladding material with a required thickness of 6071 to 100 μ by cold rolling welding, hot rolling welding, etc.
Attached to pole piece or yoke.

In general, speakers that use caps made of copper or the like generally have larger magnets than conventional speakers in order to compensate for the decrease in magnetic flux density in the magnetic gap. There were two cost-increasing factors: an increase in cost due to the comparison cap and an increase in cost due to the enlargement of the magnetic circuit. Of these, the cost increase due to the magnetic circuit was greater than the cost increase due to the cap, and was one of the major reasons why this speaker was not adopted. However, in this embodiment, the decrease in the magnetic flux density of the magnetic gear part from the conventional magnetic circuit is small, and there is no need to increase the size of the magnetic circuit.

In addition to the effects of the invention, the present invention can significantly reduce costs and is of great industrial value.

[Brief explanation of the drawing]

FIGS. 1 and 2 show the first embodiment of the present invention. A half-sectional view of the second embodiment, FIG. 3 is a half-sectional view of a general electrodynamic speaker, and FIG.
The figure is a half-sectional view of a magnetic circuit with a copper cap. 7 &... Iron plate, Ryob... Copper plate. Name of agent: Patent attorney Toshio Nakao and 1 other person 7α
-Juku Otama 7b-4 version Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In an electrodynamic speaker in which a voice coil is placed in a magnetic gap formed by a pole piece and a yoke,
An electrodynamic speaker characterized in that a cap made of a magnetic material is bonded to at least one of the magnetic gap forming portions of the pole piece and the yoke.