JPH08140183

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DESCRIPTION JPH08140183
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
diaphragm employed in an acoustic device such as a dynamic type small speaker or microphone.
[0002]
2. Description of the Related Art This type of diaphragm is manufactured by forming an
extremely thin polymer film, and as can be inferred from FIGS. 4 and 5, the general shape is
generally circular. The sub dome portion 2 bulged in the same direction as the main dome
portion 1 integrally around the main dome portion 1, and the outer peripheral portion of the sub
dome portion 2 is fixed to the rim 3 made of metal. The sub dome portion 2 is provided with a
large number of narrow grooves 4 radially at equal intervals. In such a diaphragm A, the
boundary portion 5 between the main dome portion 1 and the sub dome portion 2 is annular as
shown in FIG. 4 and is formed as a narrow flat portion as shown in FIG. The voice coil 6 is held
by adhesion to the portion 5 as shown in FIG.
[0003]
And, in the conventional diaphragm A, all the inner ends 41 of the large number of narrow
grooves 4 are located in the immediate vicinity of the boundary portion 5 as shown in FIGS. 4
and 5. .
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[0004]
By the way, the large number of the thin grooves 4 ... serve to reinforce the diaphragm A, and the
linearity of the vibration is improved as compared with the diaphragm A provided with the thin
grooves 4 ... without the thin grooves 4. And acoustic characteristics have also been found to be
desirable characteristics.
Here, the linearity of the vibration means that the range of vibration with a uniform amplitude
becomes large, and the whole diaphragm vibrates with a uniform amplitude when the amplitude
is large, but the desired amplitude when the frequency becomes large. There will be places where
vibration does not occur.
[0005]
However, when the frequency characteristics of the sensitivity of the diaphragm A in which the
voice coil 6 was fixed simply by adhesion to the boundary portion 5 were examined, as indicated
by the broken line in FIG. Dip in the relative sensitivity of It is considered that this is probably
because the phenomenon in which the portion near the boundary 5 in the sub dome 2 shown in
FIG. 5 and the boundary 5 do not vibrate together has occurred.
[0006]
Therefore, as one of the measures to eliminate the dip of the relative sensitivity generated in the
frequency band of 4 to 8 kHz conventionally, as shown in FIG. 5, the boundary portion 5 holding
the voice coil 6 and By applying the adhesive 72 so as to straddle the sub dome portion 2, the
bending rigidity of the portion has been enhanced. In the prior art, the adhesive 71 used when
bonding the voice coil 6 to the boundary portion 5 is used more and the surplus is used as the
adhesive 72 straddling the boundary portion 5 and the sub dome portion 2 or Alternatively, after
the voice coil 6 is adhered to the boundary portion 5 with the adhesive 71, the adhesive 72 is
separately applied across the boundary portion 5 and the sub dome portion 2 or the like.
[0007]
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However, even if the surplus portion of the adhesive 71 used for bonding the voice coil 6 is used
as the adhesive 72 straddling the boundary portion 5 and the sub dome portion 2, an adhesive
separately is used. Even when 72 is applied across the boundary portion 5 and the sub dome
portion 2, a countermeasure is taken to reinforce the portion across the boundary portion 5 and
the sub dome portion 2 with the adhesive 72 as in the prior art. There are problems with
workability and uniformity of the effect of improving the characteristics. That is, in the case
where the portion extending over the boundary portion 5 and the sub dome portion 2 is
reinforced with the adhesive 72, the amount of the adhesive 72 is the most appropriate amount
to keep the vibration characteristics optimum. If the amount of the agent 72 is insufficient,
uniform improvement of the vibration characteristics can not be achieved. On the other hand, it
is difficult to apply the optimum amount of adhesive 72 even to the skilled person.
[0008]
The present invention has been made in view of the above problems and circumstances, and the
reinforcing action by a large number of narrow grooves provided in the sub dome portion
extends to the portion straddling the boundary portion and the sub dome portion described
above. By taking measures, the location is reinforced, so that the part near the boundary part of
the sub dome and the boundary part are vibrated integrally, and the sound of the relative
sensitivity does not occur in the 4 to 8 kHz frequency band. The purpose is to provide a
diaphragm of the device.
[0009]
In the diaphragm of the acoustic device according to the invention as set forth in claim 1, the sub
dome portion is continuously provided around the main dome portion, and a large number of
narrow grooves are radially provided in the sub dome portion. In the diaphragm of the device,
the inner end of the narrow groove reaches the boundary between the main dome portion and
the sub dome portion.
[0010]
The diaphragm of the acoustic device according to the second aspect of the present invention is
such that the boundary is formed flat and the narrow groove crosses the boundary.
[0011]
According to the first aspect of the present invention, since the inner end of the narrow groove
reinforcing the sub dome portion reaches the boundary portion between the main dome portion
and the sub dome portion, the boundary portion and the sub dome portion The straddling
portion is reinforced by the narrow groove, and the portion near the boundary portion of the sub
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dome portion and the boundary portion easily vibrate integrally.
[0012]
According to the second aspect of the present invention, since the narrow groove crosses the
boundary, not only the portion straddling the boundary and the sub dome but also the boundary
is reinforced by the narrow groove.
For this reason, the action that the portion near the boundary portion of the sub dome portion
and the boundary portion easily vibrate integrally is further promoted.
[0013]
1 is a plan view of a diaphragm A according to an embodiment of the present invention, FIG. 2 is
an end view when the diaphragm A is cut at the center, and FIG. 3 is along the line III-III of FIG. It
is the schematic sectional drawing which expanded the part.
In these figures, 1 is a main dome portion, 2 is a sub dome portion, 3 is an edge frame, 5 is a
boundary portion between the main dome portion 1 and the sub dome portion 2, and 6 is a voice
coil. Since this is the same as the one described in FIG. 4 and FIG. 5, the detailed description
thereof is omitted.
[0014]
In this diaphragm A, as shown in FIG. 1 and FIG. 3, a large number of radially extending narrow
grooves 4 provided in the sub dome portion 2 extend across the boundary portion 5 and the
inner end 41 thereof. Reaches the inner peripheral edge 51 of the boundary 5.
Further, the adhesive 71 bonding the voice coil 6 to the boundary 5 is used only for bonding the
voice coil 6 and there is no excess or deficiency of the amount.
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[0015]
When the sensitivity frequency characteristics of the diaphragm A configured in this way were
examined as an invention, as shown by the solid line in FIG. 6 showing the characteristics, the
relative sensitivity in the 4 to 8 kHz frequency band is flat. Not to generate dips (represented by
broken lines) as in the prior art.
[0016]
Similar investigations were carried out also in the case where the inner end of the narrow groove
4 was located at the place where the boundary portion 5 was reached (in a state where the
narrow groove 4 did not cross the boundary portion 5). The relative sensitivity in the frequency
band of
[0017]
In this embodiment, the inner ends 41 of all of the multiple grooves 4 are made to reach the
boundary 5, or all the grooves 4 are made to cross the boundary 5, but one or It has been found
that the relative sensitivity in the frequency band of 4 to 8 kHz can also be flattened by doing so
for every two narrow grooves 4.
That is, in order to achieve the object of the present invention, the inner end 41 of the large
number of narrow grooves 4 may reach the boundary 5 or the boundary 5 may be crossed. Good.
[0018]
In the diaphragm A of the illustrated example, a large number of narrow grooves 4 are arranged
radially extending tangentially to a virtual circle smaller in diameter than the boundary portion 5.
It may be arranged radially extending in the radial direction.
[0019]
The boundary 5 is not necessarily flat as in the embodiment, and may be bent in a valley shape,
for example.
[0020]
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According to the present invention, the narrow groove provided in the sub dome portion is
extended inwards at the portion straddling the boundary portion and the sub dome portion and
the reinforcement of the boundary portion. This is achieved by making the inner end reach the
boundary or making the groove cross the boundary, so when forming the groove simultaneously
performed in forming the main dome portion and the sub dome portion, The above-mentioned
places and boundaries are reinforced without carrying out the above process.
Therefore, there is no need to apply the adhesive to the portion crossing the boundary portion
and the sub dome portion as in the prior art, and furthermore, there is no variation in the
characteristic improvement effect, and the acoustic characteristics are homogenized. Has the
effect of being able to
[0021]
Brief description of the drawings
[0022]
1 is a plan view of a diaphragm according to an embodiment of the present invention.
[0023]
2 is an end view when the same diaphragm is cut at the central portion.
[0024]
3 is a schematic cross-sectional view enlarging a portion along the line III-III in FIG.
[0025]
4 is a plan view of the conventional diaphragm.
[0026]
5 is a schematic cross-sectional view enlarging the main part of the conventional diaphragm.
[0027]
6 is a graph showing the sensitivity frequency characteristics of the invention and the
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conventional product.
[0028]
Explanation of sign
[0029]
A diaphragm 1 main dome portion 2 sub dome portion 4 narrow groove 5 boundary portion 41
inner end of narrow groove
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