JPH0865784

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DESCRIPTION JPH0865784
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the
structure of a repulsive magnetic circuit type speaker, and more particularly to a speaker
structure suitable for reducing the weight and thickness and improving the reproduction
frequency band.
[0002]
2. Description of the Related Art Conventionally, as shown in FIG. 8, two magnets 5 and 5
magnetized in the thickness direction are disposed so that the same poles face each other as a
magnetic circuit 1, as shown in FIG. A repulsive magnetic circuit type speaker B has been
proposed, which constitutes a repulsive magnetic circuit utilizing a magnetic field due to
repulsive magnetic flux generated on the outer peripheral side of the magnet and arranges the
voice coil 3 in the magnetic field. We proposed various types of speakers. In the figure, 2 is a
cone diaphragm, 4 is a damper, 6 is a center plate made of a magnetic material sandwiched
between the magnets 5 and 5, and is for increasing the magnetic flux density of repulsive
magnetic flux. The reference numeral 7 denotes a frame, and 8 denotes a support for coupling
and fixing the magnetic circuit member.
[0003]
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In the conventional general repulsion magnetic circuit type speaker, as shown in FIG. 8, the
upper end side of the coil bobbin 3b of the voice coil 3 or the outside of the coil portion 3a. Since
the inner peripheral portion (neck portion) of the diaphragm 2 is connected to the above, there is
a restriction in reducing the overall height of the diaphragm 2, and there is a limit in thinning the
overall height of the speaker. For example, as shown by the phantom line in the figure, when the
total height h1 of the speaker is reduced to h2 by reducing the total height of the diaphragm 2,
the half apex angle 2θ1 formed by the junction of the voice coil 3 and the diaphragm 2 is 2θ2.
It became large and was restricted by the expansion of the reproduction frequency band of the
high-pitched part.
[0004]
In order to reduce the overall thickness without increasing the half apex angle of the speaker
very much, the magnetic circuit is provided in front of the diaphragm 2 and the coil portion 3a of
the voice coil 3 is joined to the coil bobbin 3b and the diaphragm 2. It can be considered to be
positioned in front of the part, but as shown in FIGS. 9A and 9B, when a general external
magnetic circuit or an internal magnetic circuit is used as the magnetic circuit 21. In the
structure shown in the figure, the front of the diaphragm 2 is covered with a large magnetic
circuit component such as the magnet 25 or the yoke 23 so that sound wave interference occurs
and smooth frequency characteristics can not be obtained. In FIGS. 9A and 9B, 22 is a center pole
and 26 is a top plate.
[0005]
There is also proposed a speaker in which the thickness reduction is achieved by directly
bonding the inner peripheral portion of the diaphragm to the voice coil by using the abovedescribed repulsive magnetic circuit (for example, Japanese Patent Laid-Open No. 5-219592).
Gazette).
[0006]
The object of the present invention is to secure the entire height of the diaphragm for promoting
the expansion of the reproduction frequency band, and to reduce the weight and thickness of the
whole, and to cover the front part of the diaphragm with a magnetic circuit. It is an object of the
present invention to provide a speaker structure which can expand the reproduction band of the
speaker according to the above-described conventional proposal, in particular, the high sound
range according to the above-described conventional proposal.
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[0007]
SUMMARY OF THE INVENTION The structure of the speaker according to the present invention
is produced by arranging two magnets magnetized in the thickness direction so that the same
poles face each other and forming them on the outer peripheral side of the magnet In a repulsive
magnetic circuit type speaker configured to arrange a voice coil in a magnetic field due to
repulsive magnetic flux, the coil portion of the voice coil is positioned forward of the junction of
the coil bobbin and the diaphragm and the coil bobbin has an outer diameter of the diaphragm It
has a smaller diameter subcone attached.
[0008]
The coil portion of the voice coil is located forward of the junction between the coil bobbin and
the diaphragm.
In other words, since the position of the junction between the coil bobbin and the inner
peripheral portion of the diaphragm is located rearward (lower) than the coil portion of the voice
coil, the coil portion that restricted the overall height of the cone speaker vibrates. It will be
located within the height range of the board and there will be no restriction on the overall height
of the speaker.
[0009]
Further, when compared with the conventional one in which the overall height of the speaker is
h2 in FIG. 8, most of the entire width (turning width) of the coil portion is taken within the height
range of the diaphragm, Since the angle is not so large, the expansion effect of the reproduction
high frequency can be expected.
[0010]
Furthermore, since the magnetic circuit uses a repulsion magnetic circuit, the front surface of the
diaphragm is provided with the front surface of the diaphragm as in the case of arranging a
conventional internal or external magnetic circuit. Since there is nothing to block the side and
there is no interference of sound waves etc., better frequency characteristics can be obtained.
[0011]
Further, since a sub-cone having a diameter smaller than the outer diameter of the diaphragm is
attached to the coil bobbin, reproduction of a high sound range becomes possible, which is
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effective as a full range speaker.
[0012]
EXAMPLES A specific example of the structure of a speaker according to the present invention
will be described based on FIGS. 1 to 7 and 10, but the same components as those of the
conventional one described based on FIG. 8 are identical. The reference numerals are attached
and the detailed description is omitted.
FIG. 1 shows a basic configuration in the case of making a thin speaker by using a repulsion type
magnetic circuit, and as described above, a similar type has been proposed.
A indicates the entire speaker, and as the magnetic circuit 1, two ring-shaped magnets 5 and 5
magnetized in the thickness direction are disposed such that the same poles face each other, and
the center plate 6 is interposed between the two magnets. And a repulsive magnetic circuit that
uses a repulsive magnetic flux radiated in a radial manner.
[0013]
The vibration system of the speaker A is composed of a cone-shaped diaphragm 2, a voice coil 3
having a coil portion 3a, and a damper 4 for supporting the voice coil 3.
The magnetic circuit 1 is attached to a mounting portion 7a protruding from the bottom of the
frame 7, and a sleeve-like support 8 having a screw portion at the lower part is inserted into the
center of the magnetic circuit and the fixing screw 9 is inserted from the lower surface of the
mounting 7a. It is fixed.
[0014]
In the present invention, the inner peripheral portion of the diaphragm 2 is joined to the lower
side of the coil bobbin 3b. Therefore, the coil portion 3a of the voice coil 3 is joined to the inner
peripheral portion of the diaphragm 2 and the coil bobbin 3b. It will be located ahead rather than
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the part 2a.
Further, as shown in FIG. 2, in order to obtain better frequency characteristics, a sub-cone 11
mainly responsible for medium to high frequency sound reproduction and having a diameter
smaller than the outer diameter of the diaphragm 2 is attached to the coil bobbin 3b of the voice
coil 3. ing.
Further, a dustproof cloth 10 is attached for dustproofing of the upper surface portion of the
magnetic circuit 1, the inside of the voice coil 3 and the coil portion 3a, and the damper 4 has a
conductive portion 4a on the surface side to facilitate wiring. Those equipped with are used.
[0015]
In FIG. 2, the sub cone 11 is attached above the coil portion 3a located above the diaphragm 2,
and FIG. 3 is the structure where the sub cone 11 is attached below the coil portion 3a. The
dustproof cloth 10 is joined to the upper portion of the sub-cone 11, and as is apparent from the
figure, the dustproof cloth 10 can be reduced as much as possible when it is upward. The
diaphragm 2 and the sub cone 11 are joined to the coil bobbin 3 b so as not to be in contact with
the coil portion 3 a.
[0016]
In FIGS. 4 and 5, the dustproof cloth 10 has a composite shape including a semispherical central
portion 10a and a semicircular outer peripheral portion 10b, and the connecting portion 10c
between the central portion 10a and the outer peripheral portion 10b is a magnet The total
height of the speaker is reduced by fixing to 5 and reducing the portion projecting to the front of
the speaker A as much as possible. In FIGS. 6 and 7, the dustproof cloth 10 is only semicircular
and the tip of the support 8 fixing the magnetic circuit portion is mushroom-shaped, and the
outer circumference of the dustproof cloth 10 is the inner circumference. By fixing the end, the
total height of the speaker is reduced by minimizing the portion projecting to the front of the
speaker A as in FIGS. 4 and 5.
[0017]
In the configurations shown in FIGS. 2 to 7, the diaphragm 2 and the sub cone 11 are joined to
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the coil bobbin 3b so as not to contact the coil portion 3a, and the diaphragm 2 and the sub cone
11 are attached to the coil portion 3a when vibrating. Even if the contact causes abnormal noise
or the coil portion 3a generates heat, the heat is not directly transmitted to the diaphragm or the
sub cone.
[0018]
FIG. 10 compares the frequency characteristics of the speaker A according to the present
invention according to the embodiment of FIG. 2 with the conventional thinned (with a total
height h2 of the speaker) repulsive magnetic circuit type speaker B shown in FIG. As compared
with the conventional speaker B, the speaker A according to the present invention has a
significantly improved frequency characteristic of the high sound portion.
[0019]
According to the structure of the speaker of the present invention, the overall height of the
speaker can be made smaller than that of the conventional repulsion magnetic circuit type
speaker, and the thickness can be reduced.
In addition, the same diaphragm as the conventional one can be used, and there is no
deterioration of the frequency characteristic particularly in the high range.
Furthermore, the depth of the diaphragm can be made deeper compared to the conventional one,
and the half apex angle formed by the junction of the voice coil and the diaphragm can be made
smaller, and the reproduction frequency characteristic band can be expanded. . And, by providing
the sub-cone, the high range can be reproduced, and the excellent effect as a full range speaker
having the whole range compared to the conventional one is exhibited.
[0020]
Brief description of the drawings
[0021]
1 is a cross-sectional view showing the basic structure in the case of thin speaker using a
repulsive type timing circuit.
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[0022]
2 is a cross-sectional view showing an embodiment of the speaker structure according to the
present invention.
[0023]
3 is a cross-sectional view showing another example of the attachment form of the sub-cone.
[0024]
4 is a cross-sectional view showing an example of changing the shape of the dustproof cloth.
[0025]
5 is a cross-sectional view showing another example of changing the shape of the dustproof
cloth.
[0026]
6 is a cross-sectional view showing an example in which the shape of the support is changed.
[0027]
7 is a cross-sectional view showing another example of changing the shape of the support
column.
[0028]
8 is a cross-sectional view of a conventional repulsive magnetic circuit type speaker.
[0029]
9 shows an example in the case of using a normal external magnetic type magnetic circuit or an
internal magnetic type magnetic circuit as the magnetic circuit, (A) is a cross-sectional view of an
example using the external magnetic type magnetic circuit, (B) is an internal magnetic Sectional
view of an example using a magnetic circuit.
[0030]
Fig. 10 Frequency characteristics comparing characteristics of the speaker according to the
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present invention and the conventional repulsive magnetic circuit type speaker.
[0031]
Explanation of sign
[0032]
A Speaker 1 Magnetic circuit 2 Diaphragm 3 Voice coil 3a Coil part 3b Coil bobbin 4 Damper 4a
Conductive part 5 Magnet 6 Center plate 7 Frame 8 Support post 9 Fixing screw 10 Dustproof
cloth 11 Sub cone
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