JPH09130893A - Electroacoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce driving force distortion and to facilitate the manufacturing of a voice coil by winding the coil so that the widing line width may be successively denser nearer to the both ends than a central part. SOLUTION: A voice coil 7 moves in the vertical direction by the voice current flowing in the coil 7, a diaphragm is vibrated and sound is generated. The winding width W of the coil 7 is longer than the length L1 of a magnetic gap 6. The coil 7 is wound by a layer so that the winding line pitch may be successively denser nearer to the both ends than a central part within the winding width W. Thus, driving force is made nonlinear for input current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodynamic electroacoustic transducer that drives a diaphragm by an electromagnetic force.

[0002]

BACKGROUND ART electroacoustic transducer of this kind, for example, a speaker 1 ₀ electrodynamic, as shown in the schematic diagram of FIG. 4, the support plate is the center pole 3 projecting from the upper central portion The magnet 4 and the upper plate 5 are sequentially placed and fixed on the magnet 2. An annular magnetic gap 6 is formed between the inner peripheral surface of the upper plate 5 and the outer peripheral surface of the center pole 3. Further, 7 ₀ while being loosely fitted into the upper portion of the center pole 3, a voice coil supported by the frame 9 through a damper 8. This upper part of the voice coil 7 _0, the diaphragm 10 is connected, the peripheral portion of the vibration plate 10 is connected to the frame 9 through an edge 11.

[0003] In such a construction the electrodynamic loudspeaker 1 _0, is intended to generate a sound by vibrating the diaphragm 10 in the voice coil 7 ₀ is lowered by the audio current flowing in the voice coil 7 _0.

[0004]

Figure 5 [0007] is an enlarged sectional view showing a part of a magnetic gap portion 6 of conventional electrodynamic loudspeaker 1 ₀ magnetic circuit in FIG. 4, FIG. 6, FIG. 4 speakers 1
Is a diagram showing the coil length per unit winding width of the voice coil of _0, FIG. 7 is a diagram showing a magnetic flux density distribution of the magnetic gap 6 of the speaker 1 ₀ in FIG. 4, in these figures, the horizontal axis X corresponds to the displacement of voice coil 7 _0, x _1,
x ₂ indicates both end positions in the voice coil stationary state.

[0005] In FIG. 5, 3 the center pole 5 is the upper plate, 7 ₀ is a voice coil disposed in the magnetic gap 6. Winding width W of the voice coil 7 ₀ is longer than the length L1 of the magnetic gap 6, the voice coil length per unit winding width has a constant value as shown in FIG.

[0006] In the speaker 1 ₀ such electrodynamic, because the magnetic flux density distribution in the magnetic gap 6 is not uniform as shown in FIG. 7, a voice coil position disposed magnetic gap 6 The force coefficient Bg × L represented by the product of the magnetic flux density Bg of the voice coil and the length L of the voice coil greatly fluctuates due to the displacement of the voice coil.

[0007] Particularly in the lowest resonance frequency f ₀ near or below the frequency at the time of large input, protruding larger voice coil 7 ₀ from the magnetic gap 6, the force coefficient Bg
× L is greatly reduced. Therefore, the driving force Bg × L × i represented by the product of the current flowing through the force factor Bg × L and the voice coil 7 ₀ i can be a current flowing through the voice coil increases linearly, the increase in amplitude Does not increase linearly with
Therefore, the driving force is distorted. Even if the current is a sine wave, the driving force does not become a sine wave, and 2
Second and third harmonic distortion will be generated.

As a conventional example for improving such distortion of driving force, for example, JP-A-56-107698, JP-A-57-106297, and JP-A-56-98098.
Japanese Patent Laid-Open Publication No. 56-96796 and the like.

Japanese Unexamined Patent Publication No. 56-107698 discloses a structure in which a special voice coil having a rectangular cross section is used, or the number of winding layers of the voice coil is sequentially changed along the winding axis direction.

Further, Japanese Unexamined Patent Publication No. 57-106297 discloses a structure using a special voice coil whose cross-sectional shape changes so that the cross-sectional area is minimized at the center of the winding width.

Further, Japanese Patent Application Laid-Open No. 56-98098 and Japanese Utility Model Laid-Open No. 56-96796 describe a technique of forming a voice coil by a printed wire.

However, it is not easy to manufacture the voice coil by forming the voice coil with a coil or a printed wire having a special cross-sectional shape, or partially changing the number of winding layers of the voice coil, and the manufacturing cost is increased accordingly. There is a drawback that it does.

The present invention has been made in view of the above points, and can drastically reduce the driving force distortion due to the non-uniformity of the magnetic flux density distribution of the magnetic gap, and also facilitate the manufacturing and reduce the cost. It is an object of the present invention to provide an electroacoustic transducer that does not cause a rise.

[0014]

In order to achieve the above-mentioned object, the present invention is configured as follows.

That is, the present invention provides an electrodynamic electroacoustic transducer in which a voice coil having a winding width longer than the length of the magnetic gap is arranged in the magnetic gap of the magnetic circuit. However, in the winding width, the winding is performed so as to become denser toward both ends rather than the central portion.

The voice coil preferably has a circular cross section, and the voice coil may have one winding layer.

According to the electro-acoustic transducer of the present invention, since the winding pitch of the voice coil is wound so as to become denser toward both ends than in the central portion within the winding width, the magnetic flux in the magnetic gap is increased. The non-linearity of the force coefficient Bg × L due to the non-uniformity of the density distribution can be corrected to improve the driving force distortion, and a general-purpose coil having a circular cross section can be used, and the number of winding layers can be reduced. It is not necessary to change it partially, and there is no increase in manufacturing cost as in the conventional example.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an electrodynamic loudspeaker 1 according to one embodiment of the present invention. Parts corresponding to those of the conventional example of FIG. 4 are designated by the same reference numerals.

In FIG. 1, reference numeral 2 denotes a support plate having a center pole 3 projecting from the center of its upper surface, on which a magnet 4 and an upper plate 5 are sequentially mounted and fixed. An annular magnetic gap 6 is formed between the inner peripheral surface of the upper plate 5 and the outer peripheral surface of the center pole 3. A voice coil 7 is loosely fitted on the center pole 3 and is supported by the frame 9 via a damper 8. A diaphragm 10 is connected to an upper portion of the voice coil 7, and a peripheral portion of the diaphragm 10 is connected to the frame 9 via an edge 11.

In the electrodynamic speaker having such a structure, the voice current flowing in the voice coil 7 causes the voice coil 7 to move up and down to vibrate the diaphragm 10 to generate sound.

The above basic structure is the same as that of the conventional example shown in FIG.

In the speaker 1 of this embodiment, in order to improve the distortion of the driving force due to the non-uniformity of the magnetic flux density distribution in the magnetic gap 6 without increasing the manufacturing cost, the following structure is adopted. doing.

That is, FIG. 2 is an enlarged sectional view showing a part of the magnetic gap portion 6 of the magnetic circuit of the electrodynamic speaker 1 of FIG. 1, and FIG. 3 is a voice coil 7 of the speaker 1 of FIG. FIG. 4 is a diagram showing the coil length per unit winding width of, in these diagrams, the horizontal axis X corresponds to the displacement of the voice coil 7, and x ₁ and x ₂ are both end positions in the voice coil stationary state. Shows.

In FIG. 2, 3 is a center pole, 5 is an upper plate, and 7 is a voice coil arranged in the magnetic gap 6. The winding width W of the voice coil 7 is longer than the length L1 of the magnetic gap 6.

In this speaker 1, as shown in FIG. 2, the voice coil 7 is further wound in such a manner that the winding pitch becomes denser in the winding width W toward both ends than the central portion. As a result, the voice coil length per unit winding width is configured to increase from the central portion to both ends as shown in FIG. 3, whereby the driving force is made nonlinear with respect to the input current. .

As described above, since the winding pitch is changed so that the voice coil length per unit winding width has a gradient, it is possible to compensate for the non-uniformity of the magnetic flux density distribution in the magnetic gap 6 and to drive the driving force. The distortion, especially the third harmonic distortion can be significantly reduced.

Moreover, unlike the conventional example, it is not necessary to use a special coil and it is not necessary to partially change the number of winding layers, so that the manufacturing is relatively easy and the manufacturing cost may be increased. Absent.

In this embodiment, the distribution of the voice coil length per unit length is stepwise, but a smoother distribution is possible, and by changing the winding pitch, The magnetic flux density distribution shape can be freely designed. In this embodiment,
Although the number of winding layers is one, it may be plural.

Although the above embodiment has been described by applying to a speaker, the present invention may of course be applied to other electroacoustic transducers such as headphones.

[0031]

As described above, according to the present invention, the winding pitch of the voice coil arranged in the magnetic gap is wound so that the winding pitch becomes closer to both ends than the central portion within the winding width. Therefore, it is possible to compensate the non-uniformity of the magnetic flux density distribution of the magnetic gap, improve the driving force distortion, and reduce the harmonic distortion.

Moreover, a general-purpose coil having a circular cross section can be used, and it is not necessary to partially change the number of winding layers, and the manufacturing cost as in the conventional example is not increased.

[Brief description of the drawings]

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

2 is an enlarged cross-sectional view showing a part of a magnetic gap portion 6 of the magnetic circuit of the speaker 1 of FIG.

3 is a diagram showing a coil length per unit winding width of a voice coil 7 of the speaker 1 of FIG.

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

[5] The magnetic gap portion 6 of the magnetic circuit of the speaker 1 ₀ in FIG. 4
It is an expanded sectional view showing a part of.

6 is a diagram showing the coil length per unit winding width of the voice coil of the speaker 1 ₀ of FIG.

7 is a diagram showing a magnetic flux density distribution of the magnetic gap 6 of the speaker 1 ₀ of FIG.

[Explanation of symbols]

1,1 ₀ speaker second support plate 4 the magnet 6 magnetic gap 7,7 ₀ voice coil 10 diaphragm

Claims (3)

[Claims] 1. An electrokinetic electroacoustic transducer in which a voice coil having a winding width longer than the length of the magnetic gap is arranged in a magnetic gap of a magnetic circuit, wherein a winding pitch of the voice coil is the winding pitch. An electroacoustic transducer characterized in that it is wound so as to become denser toward the both ends rather than the central part within the width. 2. The electroacoustic transducer according to claim 1, wherein the voice coil has a circular cross-sectional shape. 3. The electroacoustic transducer according to claim 1, wherein the voice coil has one winding layer.