JPH09163495A - Linear voice coil for dual gap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep driving power constant regardlessly of amplitude of voice coil and to improve the efficiency of driving power. SOLUTION: A linear voice coil 7 for dual gap is inserted and arranged in a gap 5 of dual gap magnetic circuit composed of magnet 1, top plate 2 having plate thickness Tp, bottom plate 3 having plate thickness Tp and yoke 4. Winding width Lc of upper voice coil 7a and lower voice coil 7b is made equal with or less than the plate thickness Tp and winding directions are inverted each other. The total of lower section of upper voice coil 7a inside an upper magnetic gap 5a and the upper section of lower voice coil 7b inside a lower magnetic gap 5b is made equal with the winding width Lc. Thus, the total winding width of voice coils inside two magnetic gaps 5a and 5b is fixed rehardlessly of amplitude, the driving power of linear voice coil 7 for dual gap is not fluctuated, and efficiency is more improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil used in an electroacoustic transducer, and more particularly to a dual-gap linear voice coil having no output fluctuation due to amplitude.

[0002]

2. Description of the Related Art FIG. 2 is a half sectional view of a magnetic circuit and a voice coil in a first conventional example. In the figure, 1 is a magnet, 2 is a top plate having a plate thickness Tp installed on the upper part of the magnet 1, 14 is a yoke located at the lower part and outer periphery of the magnet 1, and 15 is a top plate 2. It is a magnetic gap between the yokes 14. Reference numeral 17 denotes a voice coil inserted and arranged in the magnetic gap 15. The winding width Lc of the voice coil 17 is substantially the same as or slightly smaller than the plate thickness Tp of the top plate 2.

The magnetic flux generated in the magnet 1 is the top plate 2 → the magnetic gap 15 → the yoke 14 → the magnet 1
The magnetic circuit is formed by making one round. Here, when a current is passed through the voice coil 17, the voice coil 17 is driven vertically according to the direction of the current according to Fleming's law. Here, when the magnetic flux in the magnetic gap 15 is b, the winding width of the voice coil 17 inserted in the magnetic gap 15 is Lc, so the driving force of the voice coil 17 is proportional to b · Lc.

In the prior art example 1, the magnetic flux is effectively utilized. However, the driving force fluctuates depending on the amplitude of the voice coil 17, and the magnetic flux density distribution in the magnetic gap 15 is asymmetric in the vertical direction. The operation of the voice coil 17 inserted and arranged differently depending on whether it moves upward or downward, causing second harmonic distortion in the low range of the speaker. Further, the impedance of the voice coil 17 in the high frequency range is increased, which adversely affects the high frequency characteristics of the speaker.

FIG. 3 is a half sectional view of a magnetic circuit and a voice coil in Conventional Example 2 in which the above-mentioned drawbacks of Conventional Example 1 are improved. In the figure, 1 is the same magnet as the conventional example 1, and 2 is the conventional example 1 installed above the magnet 1.
14 is the same yoke as in the conventional example 1 located on the lower and outer circumferences of the magnet 1,
Is a magnetic gap between the top plate 2 and the yoke 14. Reference numeral 27 denotes a voice coil composed of an upper voice coil 27a and a lower voice coil 27b which are inserted and arranged in the magnetic gap 15, and these upper voice coils 27a.
The winding width of the lower voice coil 27b is Lc / 2, which is half that of the voice coil 17 of Conventional Example 1, and is approximately half the plate thickness Tp of the top plate 2. However, the upper voice coil 27a and the lower voice coil 27b have opposite winding directions and are connected to each other. The total of the lower portion of the upper voice coil 27a and the upper portion of the lower voice coil 27b inserted in the magnetic gap 15 is Lc / 2.

The magnetic flux generated in the magnet 1 is the top plate 2 → the magnetic gap 15 → the yoke 14 → the magnet 1
The magnetic circuit is formed by making one round. Here, when a current is passed through the upper voice coil 27a and the lower voice coil 27b, the voice coil is driven in the vertical direction according to the direction of the current according to Fleming's law, and the total winding width of the voice coil in the magnetic gap 15 regardless of the amplitude. Is constant at Lc / 2,
There is no change in the driving force of the voice coil 27. Here, assuming that the magnetic flux in the magnetic gap 15 is b, the total winding width of the voice coil 27 inserted in the magnetic gap 15 is Lc / 2, so the driving force of the voice coil 27 is 0.5b · Lc. Is proportional to and becomes constant.

[0007]

However, 1 of the conventional example 2
A voice coil consisting of two voice coils, an upper voice coil and a lower voice coil in one magnetic gap, has half the driving force compared to the case where one voice coil is used in one magnetic gap.
Becomes less efficient.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a linear voice coil for a dual gap in which the driving force does not change regardless of the amplitude and the efficiency is improved. To do.

[0009]

In order to solve the above problems, the dual gap linear voice coil of the present invention is
Two magnetic gaps, which have opposite voice directions and two voice coils, an upper voice coil and a lower voice coil, whose winding width is equal to or smaller than the thickness of the top plate, and the magnetic flux directions of the dual gap magnetic circuits are opposite to each other. It is to be inserted and placed inside. The lower part of the upper voice coil inserted in the upper magnetic gap and the upper part of the lower voice coil inserted in the lower magnetic gap have the same winding width, and the total winding width of one voice coil is By making them equal to, the driving force of the dual-gap linear voice coil does not fluctuate, and the efficiency is further improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The dual-gap linear voice coil of the present invention is provided with a top plate 2 and a bottom plate 3 having the same plate thickness on the upper and lower parts of a magnet 1, respectively, and a yoke 4 on the outer periphery thereof. The gap 5 which is installed and has an upper magnetic gap 5a and a lower magnetic gap 5b
A dual-gap magnetic circuit for forming a dual-gap linear voice coil 7 that is inserted into the gap 5 and is connected to each other in the dual-gap linear voice coil 7. The lower part of the upper voice coil 7a, which is composed of the voice coil 7b and has a winding width equal to or smaller than the plate thickness of the top plate 2, is inserted into the upper magnetic gap 5a and the lower part is inserted into the lower magnetic gap 5b. Voice coil 7b
Is characterized in that the winding width is the same as that of the upper part and the total width is the same as the winding width of one voice coil.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view of a dual gap magnetic circuit and a dual gap linear voice coil according to the present invention. In the figure, 1 is the same magnet as the conventional example, 2 is the same top plate as the conventional example installed on the upper part of the magnet 1, and 3 is a bottom plate with a plate thickness Tp installed at the lower part of the magnet 1. Is. Reference numeral 4 is a yoke installed on the outer periphery of the magnet 1, top plate 2 and bottom plate 3, 5a is an upper magnetic gap between the top plate 2 and the yoke 4, and 5b is a lower magnetic gap between the bottom plate 3 and the yoke 4. Is a gap,
Reference numeral 5 is a gap having the upper magnetic gap 5a and the lower magnetic gap 5b.

Reference numeral 7 is a dual-gap linear voice coil consisting of an upper voice coil 7a and a lower voice coil 7b inserted in the gap 5, and the winding width Lc of the upper voice coil 7a and the lower voice coil 7b is a top plate. Although it is equal to or smaller than the plate thickness Tp of No. 2, it is desirable that it is substantially the same as the plate thickness Tp. However, the upper voice coil 7a and the lower voice coil 7b have winding directions opposite to each other and are connected to each other.

The magnetic flux generated in the magnet 1 makes one circuit in the order of top plate 2 → upper magnetic gap 5a → yoke 4 → lower magnetic gap 5b → magnet 1 to form a magnetic circuit. Here, when a current is passed through the upper voice coil 7a and the lower voice coil 7b, the current is driven in the vertical direction according to the direction of the current according to Fleming's law. A voice having the same winding width between the lower part of the upper voice coil 7a inserted in the upper magnetic gap 5a and the upper part of the lower voice coil 7b inserted in the lower magnetic gap 5b, and having a total of one voice By making the winding width of the coil equal, the total winding width of the voice coils in the two magnetic gaps 5a and 5b is constant as Lc regardless of the amplitude, and the driving force of the dual gap linear voice coil 7 varies. Moreover, the efficiency is further improved.

In the embodiment shown in FIG. 1, for comparison with the conventional examples 1 and 2, the magnet and the top plate are the same as those of the conventional example, and the unit of the winding width of the voice coil is also the same. In the embodiment, there are two magnetic gaps, and the magnetic flux density is reduced by that amount as compared with the conventional example. here,
The magnetic flux in the upper magnetic gap 5a and the lower magnetic gap 5b is set to 0.9 of the magnetic gap 15 in the conventional example,
The effective winding width is set to 0.8 by shortening the total length of each winding of the upper voice coil 7a and the lower voice coil 7b. Therefore, the magnetic flux in the magnetic gaps 5a and 5b is 0.9b, and the total winding width of the upper voice coil 7a and the lower voice coil 7b inserted in the magnetic gaps 5a and 5b is 0.8Lc. The driving force of the linear voice coil 7 for use is constant in proportion to 0.72b · Lc.

In the conventional example 1 (see FIG. 2), the magnetic gap is 1
On the other hand, when the voice coil has one winding portion, the driving force of the voice coil is proportional to the product of the magnetic flux b and the coil winding width Lc, that is, b · Lc. In the case of the conventional example 2 (see FIG. 3) having one magnetic gap and two voice coil winding portions, the driving force of the voice coil is the product of the magnetic flux b and the total effective coil winding width Lc / 2. That is, it is constant in proportion to 0.5b · Lc. In the embodiment of the present invention (see FIG. 1), when there are two magnetic gaps and the voice coil has two winding portions, the driving force of the voice coil is a total of 0.8Lc of the magnetic flux 0.9b and the effective coil winding width. Product with, that is, 0.72b
・ Proportion to Lc, which is constant and is more efficient than the conventional example.

[0016]

The dual-gap linear voice coil of the present invention is composed of an upper voice coil 7a and a lower voice coil 7b which are connected to each other and have the same winding width but opposite winding directions. And the lower magnetic gap 5 which is equal to or smaller than the plate thickness of the upper voice coil 7a inserted in the upper magnetic gap 5a.
Since the winding width of the upper part of the lower voice coil 7b inserted in b is the same, and the total is the same as the winding width of one voice coil, the linear voice coil 7 for dual gap is oscillated. The driving force can be made constant, and the current flowing through the upper voice coil 7a and the current flowing through the lower voice coil 7b are in opposite directions, so that the inductances can be canceled out from each other, thereby suppressing the increase in impedance at high frequencies. This has the effect of improving high frequency characteristics and reducing current distortion. Further, compared with the conventional example in which a coil having two winding portions is installed in one magnetic gap, the present invention has two
It is efficient because two winding parts are installed in each magnetic gap.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a dual gap magnetic circuit and a dual gap linear voice coil according to the present invention.

FIG. 2 is a half cross-sectional view of a magnetic circuit and a voice coil in Conventional Example 1.

FIG. 3 is a half sectional view of a magnetic circuit and a voice coil in Conventional Example 2.

[Explanation of symbols]

 1 magnet 2 top plate 3 bottom plate 4,14 yoke 5,15 gap 5a upper magnetic gap 5b lower magnetic gap 7 dual gap linear voice coil 7a, 27a upper voice coil 7b, 27b lower voice coil 17, 27 voice coil

Claims (1)

[Claims] 1. A top plate (2) and a bottom plate (3) having the same plate thickness are installed on the upper and lower parts of a magnet (1), respectively, and a yoke (4) is installed on the outer periphery of these plates, and the upper magnet (1) is attached. A dual gap magnetic circuit for forming a gap (5) having a gap (5a) and a lower magnetic gap (5b) is provided, and a dual gap linear voice coil (7) inserted and arranged in the gap (5).
In, the upper voice coil (7a) and the lower voice coil (7b) are connected to each other and have the same winding width but opposite winding directions.
And the winding width is equal to or smaller than the plate thickness of the top plate (2), and the lower part of the upper voice coil (7a) and the lower magnetic gap (5) are inserted into the upper magnetic gap (5a).
b) A linear voice for a dual gap, which has the same winding width as the upper part of the lower voice coil (7b) inserted in b) and has the same total winding width as one voice coil. coil.