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JPH05344592

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH05344592
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
loudspeaker, and more particularly to a loudspeaker capable of reproducing a wide frequency
range with a simple structure.
[0002]
2. Description of the Related Art As an audio speaker, there is a so-called core-key type speaker
in which a plurality of speakers having different reproduction bands are arranged on the same
axis. As a conventional example of such a core-axial speaker, one having a structure in which a
tweeter is disposed at a position coaxial with the woofer, for example, a space inside a voice coil
is known. In this core speaker, since the woofer and the tweeter are arranged with the same axis,
reproduction is performed as if sound waves from both the low frequency region and the high
frequency region are generated from the same sound source. It has good sound field
reproduction ability.
[0003]
The above-described conventional speaker has a structure in which a tweeter is disposed inside a
woofer's voice coil, so the tweeter's magnet, voice coil, and vibration can be accommodated in
this limited space. There is a problem that it is necessary to provide a plate, and there are many
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design restrictions. Moreover, in this system, since both speakers are disposed in close proximity,
it is inevitable that the strong magnetic circuit of the woofer adversely affects the magnetic
circuit of the tweeter.
[0004]
In view of the above problems, speakers as shown in FIGS. 9 to 11 have been proposed. In the
figure, reference numeral 1 denotes a magnet, 2 denotes a pole piece, 3 denotes a voice coil, 4
denotes a woofer diaphragm, and 5 denotes an elastic suspension for supporting the diaphragm
4. Inside the voice coil 3, a tweeter vibrator 6 as shown in FIGS. 10 and 11 is provided. The
tweeter vibrating body 6 is made of a conductive material such as metal, and includes a spherical
diaphragm portion 7 and a cylindrical skirt portion 8 provided around the diaphragm portion 7.
The tweeter oscillator 6 is supported by a shaft 9 fixed to the pole piece 2 via a tweeter
suspension 10 made of an elastic material. A reflector 11 is fixed to the tip of the shaft 9 so that
the phase correction of the sound wave generated from the tweeter vibrator 6 is performed.
[0005]
In the above-mentioned speaker, the skirt portion 8 of the tweeter vibrating body 6 has a
function as a coil of one turn, and a current is induced by the voice coil 3. That is, a transformer
having the voice coil 3 as a primary coil and the skirt portion 8 as a secondary coil is formed.
[0006]
In the speaker having the above configuration, the signal flowing through the voice coil 3 drives
the woofer diaphragm 4 at a frequency of several thousand kilohertz or less, and in the high
frequency region where the woofer diaphragm 4 hardly vibrates, Since the impedance of the
voice coil 3 decreases, the tweeter oscillator 6 starts to move as the current increases. Therefore,
the low frequency can be reproduced from the woofer diaphragm 4 and the high frequency can
be reproduced from the tweeter vibrator 6 without using a special frequency dividing circuit.
[0007]
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However, since the tweeter vibrating body 6 needs to perform both the function as a diaphragm
and the function as a coil, it has to be a special shape as illustrated, and the shape or material of
the diaphragm is required. There is a problem that the freedom of choice is small. In addition,
when the diaphragm is made of a conductive material such as a diaphragm, an increase in weight
over a certain degree can not be avoided, and it becomes difficult to drive with a single-turn coil,
and a minute signal There is a problem that the responsiveness to Furthermore, there is a
problem that the tweeter diaphragm 6 has to be provided in a limited range inside the voice coil
3.
[0008]
The present invention has been made in view of the above circumstances, and an object thereof
is to reduce the weight of a diaphragm for a high frequency region, and to obtain a speaker with
good response.
[0009]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention
provides a signal to a voice coil placed in a magnetic field to provide a signal to a first diaphragm
connected to the voice coil. In the speaker driven according to the second embodiment, a second
diaphragm is provided in the vicinity of the voice coil so as to be movable with respect to the first
diaphragm, and the second diaphragm is a ferromagnetic member. It is set as the structure
formed by this.
[0010]
The current of the voice coil increases in the region where the impedance of the first diaphragm
becomes low, and the second diaphragm is driven by the magnetic field generated by this
current.
[0011]
Embodiments of the present invention will be described below with reference to the drawings.
The same reference numerals as in the conventional example denote the same parts in the
drawing to simplify the description.
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[0012]
1 and 2 show a first embodiment of the present invention.
Reference numeral 20 denotes a tweeter diaphragm, which is fixed to the upper surface of the
pole piece 2 via a suspension 21.
The diaphragm 20 is formed in a thin plate shape or a film shape by a ferromagnetic material
such as steel, and as shown in FIG. 2, the surface is an S pole and the rear surface (the surface on
the pole piece side) is an N pole. It is magnetized to be The material of the diaphragm 20 is not
only a metal plate or a metal thin film, but any magnetic material that can be magnetized is
sufficient. For example, magnetic powder such as ferrite is adhered to the surface of a resin film
such as polyester. It may be The suspension 21 supports the tweeter diaphragm 20 movably with
respect to the pole piece 2 and the like, and is formed of, for example, an elastically deformable
material such as rubber, a synthetic resin, or the like. Although the suspension 21 in the
illustrated example is formed in a bellows shape provided with a plurality of bending portions so
as to facilitate elastic deformation, as long as the tweeter diaphragm 20 can be movably
supported, other materials, For example, a foamed resin material such as sponge or expanded
polystyrene may be used.
[0013]
In the speaker configured in this manner, the voice coil 3 is excited by the supply of the drive
current, and vibration is caused by the force acting on the voice coil 3 in the magnetic path
between the permanent magnet 1 and the pole piece 2 The plate 4 is driven. The diaphragm 4 is
usually formed to have a diameter of several centimeters to several tens of centimeters, and in
such a diameter, a voice coil is used at frequencies of several thousand kilohertz or less due to its
own mechanical vibration characteristics. It can be vibrated by the signal flowing through three.
Further, at a high frequency exceeding this, the woofer diaphragm 4 becomes difficult to vibrate,
so the impedance of the voice coil 3 is lowered and the current is increased, and the leakage flux
is increased, thereby being made of a ferromagnetic material The tweeter diaphragm 20 starts to
vibrate. Therefore, the low frequency can be reproduced from the woofer diaphragm 4 and the
high frequency can be reproduced from the tweeter diaphragm 20 without using a special
frequency dividing circuit. Further, the crossover frequency between the woofer and the tweeter
can be variously set by appropriately setting the material, weight and shape of each diaphragm
or suspension to obtain necessary compliance.
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[0014]
FIG. 3 shows a second embodiment. In this embodiment, the tweeter diaphragm 20 is not
positively magnetized and is not illustrated, depending on the permanent magnetic pole property
(usually N pole) of the tip of the pole piece 2. It can be polarized and vibrated by the magnetic
field generated from the voice coil 3 as in the first embodiment.
[0015]
FIG. 4 shows a third embodiment. In this third embodiment, the slit 23 is provided in a part of the
tweeter diaphragm 22 to eliminate the effect of the one-turn coil when the tweeter diaphragm 22
is formed of a conductor, and the current flowing through the coil is eliminated. Thus, it is
possible to prevent the loss due to the loss of the woofer diaphragm 4 itself which is driven by
the coil 3.
[0016]
FIG. 5 shows a fourth embodiment. In the fourth embodiment, a tweeter vibrating plate 24 whose
front side is convex is used, and by making such a shape, high-frequency sound waves generated
from the tweeter vibrating plate 24 can be widely diffused. Can.
[0017]
FIG. 6 shows a fifth embodiment. In the fifth embodiment, the tweeter vibrating plate 25 whose
front side is concave is used. By adopting such a shape, high frequency sound waves generated
from the tweeter diaphragm 24 are directed in a specific direction. It can be made to have sex.
[0018]
7 and 8 show a sixth embodiment. In the sixth embodiment, a hole 27 is provided at the center of
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the tweeter diaphragm 26 and a super tweeter diaphragm 28 is provided in the hole 27 to
provide a three-way structure.
[0019]
The tweeter diaphragm 26 and the super tweeter diaphragm 28 are supported on the tip of the
pole piece 2 via the suspensions 29 and 30, respectively, so that they can vibrate independently.
The tweeter diaphragm 26 and the super tweeter diaphragm 28 can be set to various
reproduction frequency bands by appropriately setting the materials, weights, and shapes of the
respective diaphragms or suspensions and setting the required compliance.
[0020]
In the above embodiment, the second diaphragm is supported by the pole piece by the
suspension, but another structure may be adopted without departing from the scope of the
present invention. Of course, the specific shape of each diaphragm is not limited to the above
embodiment.
[0021]
As is apparent from the above description, according to the present invention, the present
invention is characterized in that the present invention comprises a ferromagnetic member
movably relative to a first diaphragm integral with the voice coil in the vicinity of the voice coil of
a speaker Since the diaphragm 2 is provided, the current of the voice coil is increased in the
region where the impedance of the first diaphragm becomes low as well as having a good
acoustic specification that the conventional coaxial speaker has. When the second diaphragm is
driven by the magnetic field generated by the above, the following effects can be obtained based
on the operation based on the movement principle. a. Since the second diaphragm vibrates in
a region where the impedance of the first diaphragm decreases, the first and second diaphragms
are each set to a predetermined frequency band without providing a special frequency dividing
circuit in the drive circuit. , And thus, can be a simple multi-way speaker. b. The second
diaphragm may be of any material or shape as long as it is ferromagnetic and elastically
deformable, so that it is easy to process and has a low production cost. c. The freedom of
selection of the shape and material of the second diaphragm is high, so that the weight can be
easily reduced, and therefore the response to a minute signal is good. d. Not only two-way
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systems, but also multi-band systems such as three-way and four-way systems can be easily
manufactured.
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