JP2009088727

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DESCRIPTION JP2009088727
PROBLEM TO BE SOLVED: To provide a diaphragm of a substantially dome-shaped
electroacoustic transducer which has a good sound quality. SOLUTION: In a diaphragm for an
electroacoustic transducer in which the outer peripheral shape is formed in a circular shape and
the entire shape is formed in a substantially dome shape, a ridge line 2 having a substantially S
shape from the dome apex 0 toward the outer periphery in the radial direction It was formed and
it was set as the curved-surface shape asymmetrical to the boundary with this ridgeline 2.
[Selected figure] Figure 1
Electroacoustic transducer diaphragm
[0001]
The present invention relates to a diaphragm for an electroacoustic transducer, and more
particularly, to a substantially dome-shaped diaphragm having an irregular cross section.
[0002]
There are various diaphragms, such as a cone shape and a flat plate shape depending on for lowpitched sound reproduction, medium sound reproduction, etc., and there are diaphragms formed
in a dome shape for high-frequency reproduction.
[0003]
The dome-shaped diaphragm has a circular planar shape and a semicircular side shape, and is
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formed in a semispherical shape as a whole.
Then, as is well known, a driving voice coil placed in a magnetic circuit is coupled to the
diaphragm so that the vibration of the voice coil is transmitted to the diaphragm to emit sound to
the front.
Unexamined-Japanese-Patent No. 5-328488
[0004]
However, since such a dome-shaped diaphragm has the same length between the top of the
diaphragm and the outer peripheral portion to which the voice coil is coupled at any position on
the circumference, Since the transmitted vibrations are concentrated at the top of the diaphragm
in the same phase, resonance is apt to occur, and it is difficult to obtain good sound quality.
[0005]
The present invention has been proposed in view of the above, and an object thereof is to provide
a substantially dome-shaped electro-acoustic transducer diaphragm having good sound quality.
[0006]
According to the first aspect of the present invention, in the diaphragm for an electro-acoustic
transducer in which the outer peripheral shape is formed in a circular shape and the entire shape
is formed in a substantially dome shape, a substantially S shape is formed from the dome apex 0
toward the outer periphery. A ridge line (2) is formed, and it is characterized in that it has a
curved surface shape which is asymmetrical to the left and right with the ridge line (2) as a
boundary.
[0007]
In the present invention, the ridgeline passing through the dome apex can be made substantially
S-shaped to form a left and right asymmetrical curved surface to disperse the resonance, so that
the high peak in the high region can be reduced and the frequency characteristic can be
improved. Yes, there is an effect that the sound quality is good.
[0008]
Hereinafter, an embodiment of the present invention will be described with reference to the
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drawings.
[0009]
1 is a perspective view of a substantially dome-shaped diaphragm according to the present
invention, FIG. 2 is a plan view, FIG. 3 (a) is a sectional view taken along line AA in FIG. 2, and
FIG. 3 (b) is B- in FIG. B line sectional drawing, FIG.3 (c) shows CC sectional drawing in FIG.
[0010]
As shown in FIG. 1, the diaphragm 1 for electro-acoustic transducer of the present invention has
a circular outer shape, and the entire shape is formed into a circular dome shape, and the ridge
line extending to the outer periphery through the dome apex is approximately S-shaped. In the
illustrated state, the left and right diaphragms bordering the ridge line 2 are shaped as a leftright asymmetric curved surface.
[0011]
Radially extending ridge lines 4 passing through the dome apex portion 0 with respect to the
ridge line 2 and substantially orthogonal to each other are, as shown in the cross section of FIG.
0 is located, and the length and the curvature radius of the left and right first and second ridge
lines 4a and 4b are equal.
[0012]
In FIG. 2, in the AA cross section on the right side of the dome center 0, as shown in FIG. 3 (a),
the ridgeline 3 consists of the third and fourth ridgelines 3a and 3b on the left and right, and the
radius of curvature is The radius of curvature of the long first ridge line 3a is small, and the short
second ridge line 3b is formed with a large radius of curvature.
[0013]
Further, in FIG. 2, in the cross section taken along the line C-C on the left side of the dome apex
0, as shown in FIG. 3C, the ridgeline 5 is composed of left and right fifth and sixth ridgelines 5a
and 5b The radius of curvature is such that the radius of curvature of the fifth ridge line 5a with
a short length is large, and the radius of curvature of the sixth ridge line 5b with a long length is
small.
[0014]
Therefore, the vibration transmitted through the voice coil is not concentrated in the same phase
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at the top of the diaphragm, and resonance hardly occurs.
[0015]
Preferably, the diaphragm 1 for an electroacoustic transducer of this shape is manufactured by
molding and processing an aluminum foil or a magnesium foil as its material, and a voice coil
(the other end of which is arranged to be able to vibrate in the magnetic gap of the magnetic
circuit) One end of not shown) is coupled.
In addition, the outer peripheral portion is incorporated into the speaker by being fixed to a
frame (not shown) via an edge.
[0016]
In a simple dome-shaped diaphragm, when the vibration mode is measured by simulation of a
free vibration mode by the finite element method, a substantially ring-shaped axially symmetric
mode is generated at the outer periphery of the vertex because the shape is dome-shaped.
However, since the diaphragm according to the present invention has an asymmetrical crosssectional shape, the axisymmetric mode extending radially from the top is not seen, and the
resonance points are dispersed.
[0017]
FIG. 4 shows the frequency characteristics of a speaker provided with a diaphragm according to
the present invention.
The horizontal axis is frequency, and the vertical axis is sound pressure.
FIG. 5 shows the frequency characteristics of a conventional loudspeaker provided with a mere
dome-shaped diaphragm.
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[0018]
In the conventional product, a large peak is observed on the high band side, but in the present
invention, the large peak in the high band is reduced, the peak dip is reduced as compared to the
conventional product, the flat characteristic is obtained, and the sound quality is improved.
[0019]
Of course, the present invention can also be applied to a diaphragm in which an inverted dome
shape is curved toward the back surface side, that is, the magnetic circuit side.
[0020]
The perspective view of the diaphragm for electroacoustic transducers concerning one example
of the present invention is shown.
The top view of the diaphragm for electroacoustic transducers concerning one example of the
present invention is shown.
(A) is a sectional view taken along the line AA in FIG. 2, (b) is a sectional view taken along the line
BB in FIG. 2, (c) is a sectional view taken along the line CC in FIG.
The frequency characteristic of the speaker in which the diaphragm for electroacoustic
transducers of this invention was integrated is shown.
The frequency characteristic of the conventional product is shown.
Explanation of sign
[0021]
DESCRIPTION OF SYMBOLS 0 dome top part 1 diaphragm 2, 3, 4, 5 ridgeline 3a 1st ridgeline 3b
2nd ridgeline 4a 1st ridgeline 4b 2nd ridgeline 5a 1st ridgeline 5b 2nd ridgeline
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