JPS5875999A - Speaker - Google Patents

Abstract

PURPOSE:To make the winding material of a coil thick by providing two small magnets held at a specified interval having such polarity that they repel each other with a coil for generating a magnetic field in their common axial direction, and allowing a current flowed through the coil to drive the small magnets. CONSTITUTION:Two flat magnets 2a and 2b fixed to the bobbin 3 of a cone 1 with an adhesive 4, etc., are magnetized in the thickness direction. Further, a ring 6 made of a magnetic material for cutting off magnetic flux is provided at the circumference of a circular coil 5 for driving the magnets 2a and 2b in the Z-axis direction. By a magnetic field generated in the Z-axis direction when an audio current flows through the circular coil 5, electromagnetic force operates on those two magnets 2a and 2b to oscillate the cone 1. Thus, the coil 5 for driving the speaker is provided independently of an oscillation system, so the winding material of the coil is made thick to reduce the DC resistance of the coil.

Description

DETAILED DESCRIPTION OF THE INVENTION This defense is of type MM (Moving Magnet).
This is related to the type of speaker.

Most of the air-acoustic transducers used as speakers are of the moving coil type.

FIG. 1 shows a generally well-known structure as an electrodynamic speaker, in which a voice coil VC joined to a cone C is suspended in the gap of an external magnetic circuit M1, The cone C is often vibrated by passing a sound stream through the voice coil VC.

However, this type of speaker has the following problems.

l) Since the voice coil VC is part of the camera system, if the voice coil VC is reduced, the speaker's acoustic conversion efficiency 1 and frequency characteristics will deteriorate -4. Therefore, if the winding material of the voice coil VC is made thinner, if the DC resistance of the 10" voice coil VC is large, it will be necessary to increase the output of the amplifier that drives the speaker. Also, the wire diameter of the voice coil Voice coil accidents are becoming more common.

2) The speaker of fiIII true shape is shown in Fig. 7. Since the voice coil VC is suspended in the narrow gap of the magnetic circuit M1, it is difficult to release the heat generated when the voice coil is driven by the audio current2). That person, when driven by a large voice current, the voice coil VC.

Since the temperature of the speaker will rise abnormally and there is a risk of silicon loss, this will limit the receiving power of the speaker.

3) When a large amount of leakage magnetic flux from the magnetic circuit M is installed in a TV receiver, it may affect the electron beam of a CRT.

In order to solve these problems, this invention proposes a moving magnet type speaker with a fixed driving coil. explain.

Ki2zu 1 shows a schematic diagram of this invention Q) Subi 1), in which 1 is the k-th cone of the acoustic sub-radiation, 2a and 2b are fixed to the bobbin 3 of the cone 1 with adhesive 4, etc. As shown in the figure, the V layer is magnetized in the thickness direction by two flat magnets.

Reference numeral 5 denotes a circular coil for driving the magnets 2a and 2b in two axial directions, and a ring 6 of magnetic material is provided around the coil to shield magnetic flux.

With such a structure, the speaker uses the magnetic field in the Z-axis direction generated by passing an audio current through the circular coil 5 to generate the two front magnetic resonances 1-2a.

2bKM magnetic force acts to vibrate the cone 1.Next, let's examine the cone 14, drive 1III1'a, 11ζ magnetic force.

3rd [In TS1, radius &a, 'sai) circular σ) Conductor 5 a K TUIAt I 'a□Strength of magnetic field of flowing 2, Z nl+-, 1] I (zl is bio- I do not know the law of Baar θ) or r) and II.

Now, the plane of the conductor 5a is 1111/1' P-+ = l-1
1I)) Distance 1i1(+1 /, 'Gill 1) On the Z-axis, there are two small l''-7', tosoto Ivl +
.

M2 is placed and magnetized with a polarity that repels the same νC.

Now magnet M r, (M2) magnetic keyaki llB,
6+1 'a' m and Sairon, Magnet M+, (Ma
) Efficiency M K Generally M = ml・・・・・・・・・・・・
・・・・・・・・・ ・・−・ ・It is not expressed by (2).

The forces that move the S and N poles of the mag, L and MI placed at two points are as follows.

In the range where l is small, if the force moving one magneto) M+ is F rotation), then l 1 Ffzl = F(z+-)-F(Z-7)1
1 = m(H(z-1--)-H(7,-))2.

When formula (1) and formula (2) are used in formula (5) above, V is obtained.

FIG. 4 shows Ffzl and Hlzl as King's functions from equations (1) and (6).

From this figure, when the small sag magnet Ml is moved on the Z axis, the force acting on it changes significantly, and the range of Z〉0 and Z〈0
It can be seen that the direction of the force is different in the range of . - Therefore, with this f>, the speaker cone cannot be sounded without distortion.

However, if F izl can be approximated by a linear function of 2 near the operating point 2 on the Z axis, then F(zl
= F(hl+β・(z −h) ・・・・・・
--(7).

Fhi) is an odd function of 2 and i, r is 2) or 1-)F (
−z )= −F(z) ・・・・・・・・・・・・
・・・・・・・・・(111F (-h)=-F
'(lfl ・・・・・・・・・ ・・・・・・・・・
・・・・・・・・・・・・(It becomes 1ha.

Therefore, as shown in Fig. 3, 2 (hard magnet M,
When M2 is placed on the axis and the distance between the stars is fixed at 2 b, the two makunetsu l−M + 1M 2 V 1(i
ll (force is, FT = F(z) −F (Z-2b) = F(z)
+ F (2h-z) =・−・= −・・=−(l
fl). Using the above formula (7), the formula (lO) is FT = 2 F'(h) ・・・・・・・・・・・・
. . . 01), which is a constant value regardless of 2.

Therefore, at the point approximated by a -order function, the strength of the magnetic field and the plowing force of the magnets M + and M zνC become like A chains, and it is possible to emit a loud sound as a speaker.

From Figure 4, small magnet M1. The region where F izl, the force acting on M2, can be approximated by a linear function of 2 is
It can be seen that the value is around 1.0 and '=1.0.

The linearity of zV of Fbl in the vicinity of L-0 in the former is relatively good (C), and the displacement in the axial direction is not large. The type K that constitutes the system is suitable as a high-pitched speaker.

Next, in the vicinity of the latter '=i, o, λ (for example, 0.6 - u<t4) is reduced by minimizing the displacement in the axial direction, so it is suitable for a low-pitched speaker.

In this region, the linearity of F(zl with respect to 2 is the former L
Better than around -0. Shikaji 120866F
(Because there is an inflection point of -1,%F big.

However, since the latter is removed by the push-pull operation shown in equation (10) and (u), fairly good linearity cannot be obtained even in the vicinity of a 6h core. The speaker is.

Koino 1 that drives the speaker is provided separately from the vibration system 4
Therefore, the winding of the coil is l1li! By increasing the number of turns of the coil, the output of the amplifier that drives the speaker can be made smaller.In addition, the output of the amplifier that drives the speaker can be reduced by increasing the number of turns of the coil. Since the equipment and heat pipes are also available, it is possible to output the highly acclaimed audio from the speaker (ILL12).

Furthermore, since the coil can be easily magnetically shielded with a magnetic shield (this link), there are many advantages such as no restrictions on where the speaker can be installed.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional speaker, Figures 241 and 2 are schematic diagrams showing the structure of the speaker of the present invention, Figure M3 is a diagram showing the working fluid of the speaker of the present invention, Figure 4 is a diagram showing the force acting on the magnet and its Indicates the positional relationship.1. It has two layers. In 1, 1 is a floating plate, 2 a, 2 b, M+, and M2 are magnets, and a 5-piece circular coil. Figure 1

Claims (1)

[Claims] A coil is provided that holds two small +te stones magnetized by VC in the thickness direction at a constant interval with polarities that repel each other, and generates a magnetic field in the axial direction common to the two small magnets. . A speaker characterized in that the small magnet is driven by a current flowing through the coil.