JPH08140191A - Speaker - Google Patents

Abstract

PURPOSE: To provide the thin speaker of less distortion which is used in various acoustic apparatus. CONSTITUTION: First and second annular magnets 10A and 10B are coupled to the upper part of the inside wall of a yoke 1B at the interval of >=0.5mm. Thus, the thickness of the magnetic circuit is reduced in the condition of the same amplitude margin of a voice coil 8, and the thin speaker of less distortion is obtained.

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.

[0002]

2. Description of the Related Art A conventional speaker will be described below with reference to the drawings.

FIG. 4 is a half sectional view showing the structure of the above-mentioned conventional speaker, in which a yoke 1 with a center pole is provided.
The ring-shaped magnet 2 coupled to the inner wall of the yoke 1 provides a uniform magnetic gap 3 between the outer circumference of the center pole of the yoke 1 and the inner circumference of the magnet 2.
Are formed. Further, a frame 4 is coupled to the upper surface of the yoke 1, and a damper 5 and an outer peripheral portion of a cone-shaped diaphragm 6 are coupled to the frame 4, and the inner peripheral portion of these components is coupled to the voice coil 7. In addition, the coil 8 of the voice coil 7 supports the magnetic gap 3 so as not to touch the magnetic gap 3.

Further, a dust cap 9 is connected to the central upper surface of the diaphragm 6 to prevent dust from entering the magnetic gap 3.

Next, regarding the operation of this speaker, when an electric signal is input to the coil 8 of the voice coil 7, the voice coil 7 receives a force from the magnetic gap 3 in the direction of the arrow in the figure.
Moves, and this force is applied to the diaphragm 6 connected to the voice coil 7.
The diaphragm 6 was configured to generate sound on the front surface of the speaker.

[0006]

However, in the speaker having such a conventional structure, the driving force of the speaker is the length (L) of the coil 8 of the voice coil 7 fitted in the magnetic gap 3 of the magnetic circuit. The magnetic flux density (Bg) of the magnetic gap 3 is expressed by the electric current, which is originally the driving force L × Bg.
Ideally, should take a constant value with respect to the movement of the speaker, and if this value fluctuates, the sound generated from the speaker will be distorted.

For this reason, in the conventional speaker, as shown in FIG. 4, the voice coil 7 is arranged with respect to the length A of the magnetic gap 3.
Since the length B of the speaker is about the same, (A-B) of the speaker
There is a problem that a part of the voice coil 7 protrudes from the magnetic gap 3 for an amplitude of / 2 or more, the driving force L × Bg changes, and distortion occurs.

As one of the methods for reducing the occurrence of this distortion, there is a method in which A is set to be sufficiently larger than B. However, when an attempt is made to obtain a sufficient amplitude margin, the magnet 2A is set as shown in FIG. Since the dimension A becomes large and therefore the height of the speaker becomes high, there is a problem that it is not suitable for in-vehicle use where thinness is required.

The present invention solves these conventional problems,
An object of the present invention is to provide a thin speaker with low distortion.

[0010]

In order to solve this problem, a speaker of the present invention comprises a pot type yoke having a center pole, and a ring-shaped first magnet coupled to the upper part of the inner wall of the yoke. A magnetic circuit having a magnetic gap composed of a ring-shaped second magnet that is coupled to the lower portion of the first magnet with a gap of at least 0.5 mm, and a frame coupled to the upper portion of the magnetic circuit. And a voice coil which fits in the magnetic gap and is coupled to the center, and an outer peripheral portion of the diaphragm is coupled to the peripheral edge of the frame.

[0011]

With this configuration, the thickness of the magnetic gap can be kept low while ensuring the amplitude margin of the voice coil.
A low distortion and thin speaker can be easily realized.

[0012]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a half sectional view showing the structure of the speaker according to the present embodiment. In FIG. 1, 1B is a yoke with a center pole, 10A and 10B are ring-shaped magnets, and this magnet 10A is used in this embodiment. And 10B each having a thickness of 6 mm, and the magnets 10A and 10B being spaced apart by 2 mm, and coupled to the upper part of the inner peripheral wall of the yoke 1B. A magnetic circuit having an annular magnetic gap 3 having a uniform gap is formed between the magnetic circuit and the outer peripheral surface of the portion.

Reference numeral 4 is a frame coupled to the upper surface of the magnetic circuit (yoke 1B), and reference numeral 7 is a voice coil equipped with a wire ring 8 and fitted in the magnetic gap 3 without eccentricity. The length of the coil 8 of the voice coil 7 is 8 mm. Reference numeral 5 is a damper for supporting the voice coil 7, 6 is a diaphragm which is coupled around the voice coil 7 and whose outer peripheral portion is joined to the peripheral edge of the frame 4, and 9 is a top surface of the central portion of the diaphragm 6. It is a dust cap.

FIGS. 2 (a) and 2 (b) are half sectional views showing the positional relationship between the magnetic circuit and the voice coil of the above-mentioned embodiment. In this way, the magnet is divided into two parts, 10A and 10B,
Each length is A2 / 2, the distance between them is C, the length of the coil 8 of the voice coil 7 is B, and the amplitude margin is D.
When set to 1, D1 = A2 / 4 + C (where B = A
2/2 + C).

When the amplitude margin of the conventional speaker described with reference to FIG. 5 is D2 and is similarly calculated, D2 = (A
-B) / 2, and the amplitude margin D2 of this conventional speaker
And the difference in thickness of the magnetic gap 3 when the amplitude allowance D1 of the speaker of the present embodiment is set to the same value, A2 + CA = (2B
-2C) + C- (2B + C) =-2C, and the speaker of the present embodiment can reduce the thickness of the magnetic gap portion by -2C as compared with the conventional speaker.

That is, the conventional speaker has an amplitude allowance D2 when the length of the voice coil is set to 8 mm as shown in FIG.
To secure 5 mm, the thickness of the magnetic gap is 18 mm.
On the other hand, in the speaker of this embodiment, the thickness of the magnetic gap portion is 14 mm as shown in FIG. 1, and it is possible to realize a thickness reduction of 4 mm.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a half sectional view showing the structure of the speaker according to the present embodiment. This embodiment is different from the first embodiment in that the ring-shaped first magnet 10C and the second magnet 10C are the same. The point 10D is coupled to the upper portion of the outer wall of the center pole of the yoke 1C. The configuration and effects of this embodiment other than this are the same as those of the first embodiment, and therefore detailed description thereof is omitted here.

[0020]

As described above, in the speaker according to the present invention, the thickness of the magnetic gap can be suppressed to be low while ensuring the amplitude margin of the voice coil, and the low distortion and the thinning can be realized at the same time. It can greatly contribute to speakers such as.

[Brief description of drawings]

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

FIG. 2 is a half cross-sectional view of essential parts showing the positional relationship between the voice coil and the magnetic circuit according to the embodiment.

FIG. 3 is a half sectional view showing a configuration of a speaker according to a second embodiment of the present invention.

FIG. 4 is a half sectional view showing a configuration of a conventional speaker.

FIG. 5 is a half sectional view showing a configuration of a conventional speaker.

[Explanation of symbols]

 1B, 1C yoke 3 magnetic gap 4 frame 5 damper 6 diaphragm 7 voice coil 8 voice coil wire ring 9 dust cap 10A, 10B, 10C, 10D magnet

Claims (2)

[Claims] 1. A pot type yoke having a center pole, and a ring-shaped first member connected to an upper portion of an inner wall of the yoke.
And a magnetic circuit having a magnetic gap composed of a ring-shaped second magnet which is coupled to the lower part of the first magnet with a gap of at least 0.5 mm or more, and an upper part of the magnetic circuit. A speaker comprising a combined frame and a diaphragm which is connected around a voice coil fitted in the magnetic gap and whose outer peripheral portion is connected to a peripheral edge of the frame. 2. The speaker according to claim 1, wherein the first and second magnets coupled to the upper part of the inner wall of the yoke are coupled to the upper part of the outer wall of the center pole instead of the upper part of the inner wall of the yoke.