JP2003153367

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DESCRIPTION JP2003153367
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker unit, and more particularly to one using a cone speaker.
[0002]
2. Description of the Related Art An important characteristic of cone speakers is directivity. In the
case of using a cone speaker, for example, for amplification, the directivity may be narrowed. In
order to narrow the directivity, the directivity angle of the sound output from the cone speaker is
narrowed. Therefore, it is necessary to widen the vibration area of the cone of the cone speaker
or the area of the considered vibration plane to a theoretically decided size. As a method of
increasing the vibration area, there are cases where the speaker unit itself is enlarged and the
cone is enlarged. On the other hand, there is a method of attaching a horn to the front of a cone
speaker as a method of enlarging the considered vibration surface.
[0003]
However, in any of the methods, the size of the cone when viewed from the front becomes
considerably large. Therefore, the directivity can not be narrowed when there is a restriction in
the radial size of the cone aperture and the horn aperture in relation to the installation location
and the like.
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[0004]
An object of the present invention is to provide a speaker unit using a cone speaker which has a
small size and a narrow directivity.
[0005]
The loudspeaker unit according to the invention comprises a cone loudspeaker.
For the cone speaker, for example, a conventional one having a cone, a magnetic circuit, and a
voice coil can be used. A directional controller is disposed in front of this cone speaker. The
directivity controller has a rear end facing the front of the cone speaker and a front end located
forward of the rear end. The rear end is concavely curved toward the front, and the front end is
convexly curved toward the front. When the directional controller is viewed from the front, it is
desirable that the diameter of the rear end be larger than the diameter of the front end. A
circumferential surface may be provided between the front end and the rear end. For example,
the directional controller can be configured in an oval shape. The maximum diameter of the
directional controller when viewed from the front thereof is approximately equal to or larger
than the effective diameter of the cone speaker.
[0006]
In general, the directivity of the cone speaker is determined from the sound wave emitted from
the first point on the vibrating surface and the second point of the vibrating surface at a
symmetrical position with respect to the first point and the central axis of the cone speaker. The
emitted sound waves are guided by a phenomenon that is canceled by the phase difference
between the sound waves at a third point in front of the cone speaker. Therefore, in a speaker
having a small cone aperture and a small distance difference between the first and second points,
the third point at which the phase difference is a half wavelength of the sound is a position
considerably distant from the speaker central axis, Sex becomes wider. However, in the speaker
unit according to the present invention, since the directional controller is provided in front of the
cone speaker, the sound wave emitted from the first point propagates forward along the
directional controller. The propagation distance is longer than the sound wave emitted from the
second point. Therefore, the third point at which the phase difference between both sound waves
is a half wavelength of both sound waves is a position closer to the central axis of the speaker
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than in the case where no directivity controller is provided. Therefore, the speaker unit of the
present invention has narrow directivity. In particular, if the maximum diameter of the directivity
controller is approximately equal to or larger than the effective vibration diameter, the distance
traveled by the sound wave along the directivity controller becomes longer, and narrow
directivity can be achieved more efficiently. it can.
[0007]
The rear end of the directional controller can be positioned close to the front of the cone speaker.
For example, they can be disposed close to each other in a range in which the vibration surface of
the cone speaker and the rear end of the directivity controller do not contact. Specifically, it is a
range which does not contact the vibration surface of the cone speaker at about 10% or less of
the effective vibration diameter of the cone speaker.
[0008]
When configured in this manner, good control of directivity can be performed. If the distance
between the vibration surface of the cone speaker and the rear end of the directivity controller is
large, for example, at the first point, the first point is more than the sound that wraps around to
the front end of the directivity controller. The sound traveling toward the second point side
around the rear end of the directivity controller is greater, and good control of directivity can not
be performed. When the vibration surface of the cone speaker and the rear end of the directivity
controller are close to each other, the sound coming around the front end of the directivity
controller at the first point mentioned above is the rear end of the directivity controller , And the
directionality can be well controlled.
[0009]
The rear end portion of the directivity controller can be formed in a shape approximate to the
vibration plane of the cone speaker opposed thereto. With this configuration, the distance
between the rear end of the directivity controller and the vibration surface of the cone speaker
can be made close, and the directivity can be favorably controlled as described above.
Furthermore, it is possible to prevent the deterioration of the high range. That is, in general, the
area of the cross section perpendicular to the traveling direction of the sound in the passage of
sound gradually increases, so that the deterioration of the sound quality can be prevented. When
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a bag-like space is formed halfway through the passage of sound, an equalizer for cutting the
high range is formed, and the high range is degraded. By approximating the shape of the rear
end portion of the directivity controller to the vibration surface of the cone speaker, a space for
cutting such a high range is not formed, and the deterioration of the high range can be
prevented.
[0010]
The circumferential surface between the rear end and the front end of the directional controller
may also be non-concave. Because of the non-recessed shape, the circumferential surface portion,
for example, gradually increases in diameter toward the front from the front end of the rear end
portion to a constant value, and then goes forward while maintaining the constant diameter, and
then The diameter gradually decreases toward the front end, and the diameter gradually
increases from the rear end toward the front, and then gradually increases to a constant value
(the diameter at the end of the front end). The head is shaped to be connected forward to the rear
end of the front end. In any case, there is no narrowed portion with a reduced diameter in the
circumferential surface portion. Since there are no constricted portions in this way, the sound
wave surface is not deformed while propagating the sound wave forward along the
circumferential surface, and the directivity is not adversely affected.
[0011]
The center-to-center distance between the front end and the rear end of the directivity controller
may be larger than the maximum diameter of the directivity controller as viewed from the front.
In this way, the propagation distance along which the sound wave travels along the directivity
controller becomes long, and narrow directivity can be achieved more efficiently.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION A speaker unit according to an embodiment
of the present invention has a cone speaker 2 as shown in FIG. The cone speaker 2 has a
diaphragm or cone 4. A dust cap 6 is provided at the center of the cone 4. Although not shown, a
voice coil is provided inside the dust cap 6. The magnet is indicated by 8 and the base portion of
the pole piece by 10. A voice coil is located around the pole piece, and a magnet 8 is located
around the voice coil.
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[0013]
A directional controller 12 is disposed on the front side of the cone speaker 2. The directivity
controller 12 is a hollow body made of, for example, a synthetic resin, and has a generally oval
shape including a front end portion 14, a circumferential surface portion 16 and a rear end
portion 18.
[0014]
The rear end portion 18 is located inside the front opening of the cone 4 and has a recess 18 a
formed in the center thereof at the inside of the directivity controller 12 so as to be concave
toward the inside. The concave portion 18 a has a hemispherical concave surface similar to the
shape of the dust cap 6, and the center thereof is disposed coincident with and close to the top of
the dust cap 6 (the central axis of the cone speaker 2) It is done. For example, the distance is set
to approximately 0.1 times the effective vibration diameter of the cone speaker (the distance
between the central portions of the bellows portions at the outermost periphery of the cone
surface of the cone speaker 2). The curved portion 18b is formed concentrically with the recess
18a. The curved portion 18 b is formed in an annular shape whose diameter gradually increases
toward the front. Furthermore, the curved portion 18 b is formed to be concave toward the inside
of the directional controller 12.
[0015]
The circumferential surface portion 16 has a bending portion 16a connected to the bending
portion 18b. The curved portion 16a is also formed in an annular portion concentric with the
recess 18a, and the diameter gradually increases toward the front. However, when viewed from
the inside of the directional controller 12, it is formed to be convex outward. A body portion 16b
is formed continuously with the front edge of the curved portion 16a. The body portion 16b is
also formed in an annular shape concentric with the recess 18b, and the diameter thereof is
distracted by a predetermined distance toward the front while maintaining a constant value (a
length equal to the diameter of the front edge of the bending portion 18a). doing. A curved
portion 16c is formed in communication with the body portion 16b. The curved portion 16c is
also formed in an annular shape concentric with the recess 18a, and the diameter gradually
decreases from the value of the diameter of the body portion 16b toward the front, and from the
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inside to the outside of the directivity controller 12 It is convexly formed. As described above, the
circumferential surface portion 16 has a non-concave shape without a narrowed portion whose
diameter decreases.
[0016]
The front end portion 14 is formed continuously with the curved portion 16c of the
circumferential surface portion 16, is a curved body formed concentrically with the recess 18b,
and has a cap shape formed to be convex toward the front.
[0017]
The longitudinal cross-sectional shape of the directivity controller 12 is formed as a straight line
connecting the center of the front end portion 14 and the center of the rear end portion 18, that
is, symmetrical with the central axis of the directivity controller 12 as an axis of symmetry. There
is.
[0018]
The directivity controller 12 is formed to be smooth from the rear end 18 toward the front end
14.
In the directivity controller 12, the maximum diameter (maximum diameter of the curved portion
16 a) D of the rear end 18 is formed larger than the maximum diameter of the front end 14.
The maximum diameter D of the directivity controller 12 is the diameter of the body portion 16
b, which is set larger than the effective vibration diameter of the cone 4 of the cone speaker 2.
Further, a length dimension L of the directivity controller 12 which is a distance from the center
of the front end portion 14 of the directivity controller 12 to the center of the rear end portion
18 is set larger than the maximum diameter D.
[0019]
In the speaker unit configured as described above, if the directivity controller 12 is not provided,
as shown in FIG. 2, it is at the outermost part of the space formed by the rear end 18 of the
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directivity controller 12 and the cone speaker 2. It is assumed that a sound wave of a certain
frequency emitted from points a and b symmetrical to each other with respect to the central axis
causes a half-wave phase difference at a point c1 and causes a dip. The directivity is determined
by the position where this dip occurs, and the directivity becomes wider as the dip occurs at a
point farther from the central axis of the cone speaker 2, and the directivity becomes more
pronounced as the dip occurs at a position closer to the central axis of the cone speaker 2 Sex
becomes narrow. When the directivity controller 12 is provided, sound waves of a certain
frequency from the point a are similarly emitted, but a part of the sound waves radiated from the
point b is the rear end of the directivity controller 12 18, through the circumferential surface
portion 16 and the front end portion 14, wrap around to the point a side, and at the point c
closer to the center side of the directivity controller 12 than the point c1, a phase difference of
half wave with the sound wave from the point a occurs A dip occurs. That is, the propagation
distance of the sound wave from the point b is increased by the directivity controller 12, and the
point at which the dip occurs is close to the central axis of the speaker 2 and has narrow
directivity. Therefore, by providing the directivity controller 12, narrow directivity can be
achieved without increasing the diameter of the cone speaker 2.
[0020]
Moreover, in this cone speaker, since the effective diameter of vibration of the cone 4 and the
maximum diameter D of the directivity controller 12 are set to substantially the same size, the
sound wave emitted from the cone speaker 2, particularly the point b. The sound wave emitted
from the part that must travel around the directional controller 12 to reach the point c
propagates more propagation distance and produces a half-wave phase difference, so It can be
narrow directional. Further, since the length dimension L of the directivity controller 12 is made
longer than the maximum diameter D of the directivity controller 12, the propagation distance
can be similarly extended, and narrow directivity can be ensured more reliably. Can.
Furthermore, since no necking exists in the entire circumferential surface portion 16, directivity
is not disturbed. In addition, since the shape of the rear end 18 of the directivity controller 12 is
similar to the opposing surface of the cone 4 and the rear end 18 is disposed close to the cone 4,
the high-pitched range may deteriorate Absent.
[0021]
In the directivity controller 12 of the above-described embodiment, the peripheral surface
portion 16 is shown to have the body portion 16b, but instead of removing the body portion 16b,
the curved portion 16a may be extended.
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[0022]
As described above, in the speaker unit according to the present invention, since the directivity
controller is provided in front of the cone speaker, narrow directivity can be obtained without
increasing the diameter of the cone speaker. .
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