JPH0458700

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DESCRIPTION JPH0458700
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
dome-shaped diaphragm effective as a diaphragm for middle and high-tone speakers. 2.
Description of the Related Art In recent years, dome-shaped speakers are widely used as midhigh pitched speakers, and it is desirable to increase the high frequency reproduction limit
frequency as much as possible. Heretofore, among various dome shapes, one having the same
dome weight and having the same spherical surface is considered to have the highest high
frequency reproduction limit frequency, and the dome having the spherical shape as shown in
FIG. Could be used. Hereinafter, a conventional dome-shaped diaphragm will be described. As
shown in FIG. 2, the voice coil bonding portion 2 is a vertical portion to which the bobbin of the
voice coil is fitted and bonded, and the voice coil vibration is transmitted to the dome portion.
The edge bonding portion 3 is a horizontal collar for bonding an edge that supports the entire
diaphragm to which the voice coil is bonded. The dome portion 1 has a shape in which a part of a
spherical surface formed by a constant diameter is cut. FIG. 3 shows the sound pressure
frequency characteristics of a conventional dome-shaped high-sounding speaker with a diameter
of 2 cm using a spherical dome portion in dotted lines. This diaphragm material is a 50-micronthick laminated mica, and the dome shape is a spherical surface with a diameter of 32 mm cut at
a height of E 3.4 mm. The weight of the diaphragm is 70 mg in total of the dome part, the voice
coil bonded part, the work and the toe bonded part. As shown in the figure, there is a peak at 30
KHz, which is the first order high frequency resonance frequency. In the case of a dome-shaped
speaker, since the first high-frequency resonance frequency is regarded as a high-frequency
reproduction limit frequency, the high-frequency reproduction limit of this 2.5 cm-diameter
dome-type high-sound speaker using a conventional spherical dome-shaped diaphragm The
frequency is 30 KHz. Problems to be Solved by the Invention In the dome-shaped speaker using
such a conventional dome-shaped diaphragm, the material of the diaphragm is thickened in order
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to increase the high-frequency reproduction limit frequency, ie, the first high-frequency
resonance frequency. If the shape of the dome portion has to be made a deeper spherical surface,
then the weight of the diaphragm is increased and the sound pressure level of the speaker is
lowered. The present invention solves the above problems, and provides a dome-shaped
diaphragm in which the high frequency reproduction limit frequency is increased without
increasing the weight of the diaphragm. Means for Solving the Problems In order to achieve the
above object, the present invention can make an ellipse whose major axis is 1.1 to 2 times longer
than the minor axis, with the minor axis as the axis of rotation. A small portion of the flat
ellipsoidal rotor surface, which can be cut by a plane perpendicular to the rotation axis, has a
dome shape.
The present invention has the above-described configuration, while the weight of the
conventional spherical dome is the same, but the strength of the inner circumferential portion of
the dome is lowered, and the slope of the dome outer circumferential portion is further reduced
within 0 range It can be made larger and the first higher resonance frequency can be raised.
Embodiment An embodiment of the present invention will be described below with reference to
FIGS. 1 and 3. FIG. As shown in FIG. 1, the voice coil bonding portion 2 is a vertical portion to
which the bobbin of the voice coil is fitted and bonded, and the voice coil vibration is transmitted
to the dome portion 4. Mata and edge bonding portions 3 are horizontal collars for bonding
edges supporting the entire diaphragm to which the voice coil is bonded, and these are the same
as conventional ones. On the other hand, the dome portion 4 is a flat elliptical rotary body
surface formed by using an ellipse whose major axis is 1.1 to 2 times longer than the minor axis
and whose minor axis is the rotational axis, the plane perpendicular to the rotational axis The
small part that can be cut by using is the shape. The operation of the above configuration will be
described. First, it is well known that it is necessary to increase the slope of the dome near the
voice coil, that is, the slope of the dome outer periphery, in order to increase the first high-order
resonance frequency of the dome-shaped diaphragm. However, simply increasing the slope of the
dome periphery increases the weight of the entire dome. That is, if the inner peripheral portion is
not lightened by an increase in the weight of the outer peripheral portion due to an increase in
the slope of the dome at the outer peripheral portion, the overall weight is increased. However, in
the present invention, since the dome section cross-sectional shape is a flat ellipse, in addition to
the large gradient of the dome outer peripheral part, the gradient of the dome inner peripheral
part becomes small conversely, the weight of the dome inner peripheral part is reduced. It is
possible. In addition, if the slope of the inner peripheral part of the dome is too small, the
strength of the inner peripheral part may be reduced to cause abnormal resonance at a low
frequency or to lower the first high-resonance frequency. In the present invention, since the
length of the major axis is 1.1 to 2 times the length of the minor axis, the slope of the inner
periphery of the dome does not become too small. As a result, although having the same weight
as the conventional spherical dome, the strength of the inner peripheral portion of the dome is
lowered, and the first high-resonance frequency can be increased without occurrence of
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abnormal resonance or the like. The solid line in FIG. 3 shows the sound pressure frequency
characteristics of the dome-shaped high-tone speaker of 2.5 cm in diameter using the domeshaped diaphragm of the embodiment of the present invention. The diaphragm material is a 50
micron thick laminated mica as in the prior art.
The dome shape is a small portion formed by cutting an ellipse having a major axis of 27.74 mm
5 and a minor axis of 19 ° 62 mm with the minor axis direction as the rotational axis, in a plane
perpendicular to the rotational axis of the flat ellipsoid rotary body surface, Its height is 6.02
mm. The weight of the diaphragm is <70 mg, which is the same as that of the conventional
example, as a total of the dome portion 4, the voice coil bonding portion 2 and the edge bonding
portion 3. As shown in the figure, it can be seen that the first order high resonance frequency
extends to 33 KHz. Not only that, in the prior art there is a second peak around 50 KHz, and the
sound pressure frequency characteristics are uneven above the first higher resonance frequency,
whereas the one according to the present invention is the first The sound pressure frequency
characteristic is gently attenuated above the high resonance frequency, and there is also an effect
that the unnecessary resonance sound is small. In the embodiment of the present invention, the
dome-shaped diaphragm includes the dome portion 4, the voice coil bonding portion 2, and the
edge bonding portion 3, but the type without the edge bonding portion or the voice coil bobbin
and the dome portion are integrally molded. It goes without saying that other types of dome
diaphragms and other types of dome diaphragms are also effective. As apparent from the
embodiments of the present invention as described above, according to the present invention,
although the weight of the conventional spherical dome is the same, the strength of the inner
periphery of the dome is lowered to cause abnormal resonance and the like. Since the slope of
the dome outer peripheral portion can be made larger within the range where there is no noise, it
is possible to raise the high frequency reproduction limit frequency without increasing the
diaphragm weight. In addition, the sound pressure frequency characteristic is gently attenuated
above the first high-order resonance frequency, and there is also an effect that the unnecessary
resonance sound is small, and the practical effect is extremely large.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a sectional view of a dome-shaped diaphragm according to an embodiment of the
present invention, FIG. 2 is a sectional view of a conventional dome-shaped diaphragm, and FIG.
3 is an aperture using the dome-shaped diaphragm according to an embodiment of the present
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invention It is a sound pressure frequency-characteristics figure of a 2.5 cm-diameter domeshaped high-sound speaker using a 2.5-cm dome-shaped high-sound speaker and a conventional
dome-shaped diaphragm.
2 ... voice coil bonding portion, 3 ... edge bonding portion, 4 ... dome portion. Agent's Name
Attorney Attorney Kanno Weight Ha or 1 Person C Su Ibaraki
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