JP2000278793

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DESCRIPTION JP2000278793
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
multifunctional sounding body incorporated in a mobile communication device such as a cellular
phone or a pager to notify a user of an incoming call by sound or vibration.
[0002]
2. Description of the Related Art Generally, these portable devices are configured to be able to
switch between emitting a buzzer sound and a melody sound to notify a user of an incoming call
or generating vibration without emitting a sound. Therefore, a structure has been adopted in
which a sound producing body for generating sound similar to a small speaker and a vibrating
body for generating vibration for rotating an eccentric weight by a small motor are incorporated.
As described above, incorporating both a sound generator and a vibrator was disadvantageous in
terms of downsizing and cost reduction of the device, but in recent years, it has been proposed
that one sound generator generates both sound and vibration. It is done.
[0003]
FIG. 2 is disclosed in Japanese Utility Model Laid-Open Publication No. 5-85192. A case
composed of a cover 1 and a bottom plate 2 supports a circular first diaphragm 3 on the outer
periphery, and a coil is attached to the first diaphragm 3 4 is fixed. In addition, the second
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diaphragm 5 is attached to the case, and the magnet 6 is fixed to the central portion of the
second diaphragm 5. A yoke 7 is fixed to the bottom plate 2. A magnetic circuit is formed by the
magnet 6 and the yoke 7, and the coil 4 is located in a magnetic gap formed by the outer
periphery of the magnet 6 and the inner periphery of the hole at the central portion of the yoke
7.
[0004]
When an electric signal having a certain frequency is supplied to the coil 4, an electromagnetic
force acts between the coil 4 and the magnetic circuit to start oscillating with each other. At this
time, if the frequency of the electric signal is high to a certain extent and in the audible frequency
range, the vibration of the first diaphragm 3 to which the coil 4 is fixed becomes large and
generates a buzzer sound and a melody sound according to the signal configuration. On the other
hand, the second diaphragm hardly vibrates because the natural frequency is low. If the
frequency of the signal is relatively low below the audible frequency band, no sound is produced
from the first diaphragm 3, and instead the vibration of the second diaphragm 5 to which the
magnet is fixed is increased and this vibration is It is transmitted to the portable device
incorporating the sound generator through the case to notify the user of the incoming call.
[0005]
In this way, one sounding body performs two operations of sound generation and vibration, but
in order to transmit a sufficiently large vibration in the vibration mode to the case of the
sounding body and to the device incorporating this sounding body, The energy of vibration must
be large, and the mass of the vibrating part must be large. In the case of the example of FIG. 2, it
is the 2nd diaphragm 5 and the magnet 6 that comprise a vibration part, and mass is not very
large. Japanese Patent Application Laid-Open No. 10-229596, which is a later filed application by
the same applicant as the above-mentioned new invention, shows a configuration in which the
yoke 7 is also mounted on the second diaphragm 5 and added to the vibrating mass. The
increase in mass is not sufficient.
[0006]
FIG. 3 shows a sound generator disclosed in Japanese Patent Application Laid-Open No. 10215499. The outer periphery of the first diaphragm 13 to which the coil 14 is fixed is supported
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on the upper surface side of the cover 11, while the second vibration is applied to the lower
surface of the cover 11. The outer periphery of the plate 15 is fixed. A magnet 16 provided with
a top plate 18, a yoke 17 and a weight 19 are mounted on the second diaphragm 15. As shown
in the figure, the yoke 17 is a deep dish, but the wall thickness is not very large. The weight 19
also has a deep dish shape and houses the yoke 17 inside, but the thickness of the weight 19 is
much larger than that of the yoke 17. Therefore, in the structure of FIG. 3, the addition of the
weight 19 significantly increases the mass of the vibrating portion, thereby increasing the
vibration energy.
[0007]
In the prior art shown in FIG. 3, the purpose of increasing the vibration energy by increasing the
mass of the vibrating portion by arranging the weight 19 on the outer periphery of the yoke 17
has been achieved. Add one weight and increase parts cost. In addition, an increase in labor for
parts management, an assembly process for connecting the yoke 17 and the weight 19 is
required, and a failure in the process results in a decrease in yield and the like, which also
increases the manufacturing cost. Furthermore, when the user receives an impact due to an
external force, for example, when the user accidentally removes the device incorporating the
sound generator, the connection between the yoke 17 and the weight 19 may be shifted or
separated. The present invention solves this problem and realizes a highly reliable multifunctional sounding body with a simple structure.
[0008]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, in the present
invention, the yoke and the weight are manufactured as an integral part from the beginning. As a
result, the number of components is reduced by one component, which has conventionally been
two components, and there is no fear that the joint parts are separated and the components fall
off.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below based on the drawings. FIG. 1 is a cross-sectional view of an embodiment of a
sound generator according to the present invention. A second diaphragm 25 of a metal such as
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stainless steel is fixed to the lower surface side of a cover 21 made of plastic or the like, and a
yoke 27 of a magnetic material such as pure iron or permalloy is jointed thereto by point
welding. A magnet 26 is fixed to the yoke 27, and a top plate 28 made of a magnetic material is
provided on the top surface of the magnet 26. A first diaphragm 23 molded of polyimide,
polyester or the like is attached to the upper surface side of the cover 21 and a coil 24 is fixed to
the lower surface thereof. The coil 24 is located in a magnetic gap formed by the outer periphery
of the top plate 28 and the inner periphery of the yoke 27.
[0010]
The basic operation of the sound generator of FIG. 1 is the same as that of the conventional one,
and when a signal current of audio frequency is supplied to the coil 24, the first diaphragm
vibrates to emit an audible sound such as a buzzer sound, melody or voice. When a lower
frequency signal is used, the second diaphragm 25 in which the yoke 27 and the magnet 26 are
integrated vibrates, and this vibration is transmitted through the cover 21 to the portable device
incorporating the sound producing body.
[0011]
The characteristic of this sound-producing body is that the cross section of the short cylindrical
outer peripheral portion of the yoke 27 is made significantly thicker in both the radial direction
and the vertical direction than the disk-like bottom portion, and this portion is weighted.
In the prior art shown in FIG. 3, the yoke 17 is a thin-walled bowl-like shape, and the weight 19
on the outer periphery is a separate component from the yoke 17. That is, in the case of FIG. 1,
the outer diameter of the yoke 27 is up to about the line 29, and the weight portion on the
outside thereof is joined separately from the yoke. However, in the present invention, the yoke
27 is integrated with the weight to achieve the purpose with a simple structure. The material of
the yoke 27 is a metal of a magnetic substance, so that the specific gravity is large, and the mass
is sufficiently increased by increasing the volume to perform a weight function. The yoke 27
having such a shape can be manufactured without difficulty by press processing or automatic
disc processing.
[0012]
As apparent from the above description, according to the present invention, it is not necessary to
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use separate weights as in the prior art in order to increase the mass of the vibrator, and the
number of parts is reduced to manufacture the parts. There is no need for a process, and no
process for joining a weight to a yoke is also required, and no failure occurs in these processes.
And since the yoke and the weight are an integral part, there is no risk that the joint will separate
and the part will come off when it receives an impact. As a result, a multifunctional sounding
body having two functions of sounding and vibration and having high reliability can be realized
inexpensively with a simple structure.
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