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JPH08186895

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH08186895
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electromagnetic type sounding body which vibrates a diaphragm by a magnetic circuit in which a
coil and a magnet are arranged on a yoke to generate a sound, and in particular, to the yoke and
the coil. It relates to a short prevention structure.
[0002]
2. Description of the Related Art As shown in FIGS. 6 and 7, an electromagnetic type sounding
body has a disk-like yoke 2 with a center pole portion 2a projecting in the center, and a coil 4
and a ring concentrically disposed thereon. The diaphragm 8 is vibrated by the magnetic circuit
composed of the magnet 6 and the sound is generated. In order to electrically connect the coil 4
in the electromagnetic speaker to the outside, the coil terminal 4 a is soldered to the substrate 10
provided below the yoke 2 to obtain conduction. The coil wire which comprises this coil 4 is
comprised from the conductor 12, such as copper, and the insulating layer 14 and the contact
bonding layer 16 which were formed in piles on the outer periphery, as shown in FIG. For this
reason, when the coil terminal 4a shown in FIG. 7 is pulled to lead to the direction of the
substrate 10 and it is loosened or rubbed, as shown in FIG. 9, the adhesive layer 16 and the
insulating layer 14 of the coil wire of the loosened portion. But the conductor 12 is exposed.
When the exposed conductor 12 comes in contact with the yoke 2, the coil 4 and the yoke 2
short-circuit, which causes trouble in the generation of sound.
03-05-2019
1
[0003]
Conventionally, the following measures have been taken to prevent the short circuit failure as
described above. That is, by using a plastic bobbin 18 as shown in FIGS. 10 and 11 or providing
an insulating spacer 20 between the coil 4 and the yoke 2 as shown in FIGS. It was made not to
contact the yoke 2. Moreover, as shown in FIG.14 and FIG.15, the adhesive agent 22 was apply |
coated to the coil terminal 4a, insulation and fixing were performed, and a short circuit may be
prevented.
[0004]
The use of a bobbin 18 as shown in FIGS. 10 and 11 requires a mold for plastic molding of the
bobbin 18, and maintenance of the mold is also continuously required. turn into. Also in
assembling, in order to prevent the floating of the bobbin 18, an adhesive is applied to the yoke 2
and then the bobbin 18 is attached. At this time, as shown in FIG. After inserting the guide
portion 18a into the guide hole 2b of the yoke 2 and the guide hole 10a of the substrate 10 and
drying the adhesive, the tip of the guide portion 18a is fixed by heat caulking on the lower
surface side of the substrate 10. As described above, the use of the bobbin 18 has many
problems such as the cost and maintenance of the mold, an increase in the number of assembling
steps, and an increase in the cost due to them.
[0005]
Further, as shown in FIGS. 12 and 13, when the insulating spacer 20 is used, a die for pressing
and forming for forming the insulating spacer 20 is necessary, and an adhesive for fixing to the
yoke 2 is used. A coating operation and a drying operation in a drying oven are also required.
Further, since the disk-shaped insulating spacer 20 has no portion interposed between the center
pole portion 2a of the yoke 2 and the inner diameter portion of the coil 4, the inner diameter
portion of the coil 4 can not be protected. Also, due to the generation of static electricity, the
insulating spacers 20 may overlap with each other at the time of assembly, resulting in inability
to remove them or dust may be attached. As described above, even when the insulating spacer
20 is used, the workability is poor due to the mold, the adhesive, the cleaning, the static
electricity, and the like, and there are problems in the number of processes, the yield, and the
cost.
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2
[0006]
Furthermore, as shown in FIG. 14 and FIG. 15, when the adhesive 22 is used, the dispersion of
the application amount due to the dispenser, the scattering of the adhesive, the floating of the
magnet 6 caused by these, and the adhesion due to the dispersion of the application amount It
requires many operations such as coil shorting due to uneven thickness of the agent, the
necessity of drying operation, etc., and there are problems in terms of man-hour, yield and cost.
[0007]
Moreover, although the adhesive agent is used also in any of these measures, when the drying
was not enough, the curing defect may arise.
[0008]
The present invention has been made in view of the above problems, and an object thereof is to
improve the workability, reliability and yield without using a special member, and to reduce the
number of steps and cost of the coil and the yoke in an electromagnetic speaker. To provide a
short protection structure.
[0009]
SUMMARY OF THE INVENTION The structure for preventing a short circuit between a coil and a
yoke in an electromagnetic type sounding body according to the present invention is an
electromagnetic wave generating vibration by vibrating a diaphragm by a magnetic circuit in
which a coil and a magnet are arranged on the yoke. In the type sound generator, an insulating
film is formed on the surface of the yoke.
[0010]
The outer periphery of the yoke in the present invention is covered with an insulating film.
For this reason, even if the coil contacts the yoke, it does not electrically conduct, and it is
possible to prevent the short circuit with certainty.
In particular, since the insulating coating is formed by vapor phase coating, the edge portion and
the like are uniformly coated as well as the flat portion, and the magnet and the like placed on
the yoke do not float, and the magnet and the like The adhesion at the time of adhesion can also
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be enhanced.
[0011]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a cross-sectional view of
an electromagnetic speaker according to an embodiment of the present invention.
This electromagnetic type sounding body has a cylindrical cover 24, a diaphragm 26 supported
in the inside, and a disk-shaped yoke arranged such that a center pole portion 28a projecting
from the center faces the diaphragm 26. 28, a coil 30 and a magnet 32 arranged concentrically
on the yoke 28, and a substrate 34 for closing the opening below the cover 24 and supporting
the yoke 28 and the like and for connecting the coil end of the coil 30; It consists of
[0012]
As shown in FIG. 2 and FIG. 3, an insulating film 36 is formed on the surface of the yoke 28 in
this embodiment by vapor phase coating which is one of chemical vapor deposition.
As shown in FIGS. 4 and 5, when the coil 30 is mounted on the yoke 28, the insulating coating 36
intervenes between the coil 30 and the yoke 28, and these are insulated. The entire surface of
the yoke 28 is covered with the insulating film 36. Therefore, the yoke 28 not only insulates
between the main body of the disk-like yoke 28 and the coil 30, but also the center pole portion
28a of the yoke 28 and the coil 30 It intervenes between the inner diameter portion to further
ensure insulation, and also prevents the center pole portion 28a from contacting and damaging
the inner diameter portion of the coil 30. Further, since the space between the yoke 28 and the
substrate 34 is also insulated by the insulating film 36 formed on the lower surface of the yoke
28, even if the connection portion between the coil terminal and the substrate 34 is provided on
the upper surface of the substrate 34 It can be insulated.
[0013]
The vapor-phase coating forming the insulating film 36 can uniformly coat the sharp corners and
edges of the adherend, which has been difficult in conventional liquid coating and powder
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4
coating, in the same manner as a flat surface. It is a method. In addition, the coating thickness is
easy to control, and has many excellent features such as moisture resistance, rust prevention, and
corrosion prevention. For this reason, this vapor phase coating is most suitable for coating a
three-dimensional structure such as the yoke 28 made of a special metal that is soft and easily
corroded.
[0014]
In this embodiment, the coil 30 wound and formed in advance is attached to the yoke 28.
However, since the coil 30 and the yoke 28 are reliably insulated by the insulating film 36, It is
also possible to form a coil 30 by winding a coil wire directly on the center pole portion 28 a of
the yoke 28.
[0015]
According to the present invention, the insulating film is formed on the surface of the yoke to
insulate the coil, so that it is possible to prevent the short circuit between the coil end and the
yoke, as well as the conventional bobbin and the insulation. Workability and reliability can be
improved without requiring an extra space or member as in the case of preventing a short circuit
by a spacer or an adhesive.
[0016]
Further, since the bobbin, the insulating spacer and the like can be eliminated, the space in the
cover can be effectively utilized, and the electromagnetic speaker can be miniaturized and
thinned.
[0017]
Furthermore, it is also possible to wind the coil directly on the yoke, which can eliminate the
assembly operation of bonding the preformed coil and the yoke.
[0018]
Brief description of the drawings
[0019]
1 is a cross-sectional view of an electromagnetic speaker according to an embodiment of the
present invention showing a short prevention structure.
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[0020]
2 is a perspective view of the yoke shown in FIG.
[0021]
3 is a front view of the yoke shown in FIG.
[0022]
4 is a perspective view showing a state in which a coil and a magnet are attached to the yoke
shown in FIG.
[0023]
5 is a cross-sectional view of the yoke etc. shown in FIG.
[0024]
6 is a perspective view showing a conventional yoke and coil.
[0025]
7 is a cross-sectional view of a conventional electromagnetic type sounding body incorporating
the yoke shown in FIG.
[0026]
8 is a cross-sectional view of the coil wire shown in FIG.
[0027]
9 is a cross-sectional view of the coil wire showing a state in which the coating of the coil end
portion shown in FIG. 6 is peeled off.
[0028]
10 is a perspective view showing a conventional short prevention structure using a bobbin.
[0029]
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11 is a cross-sectional view of an electromagnetic speaker according to the structure shown in
FIG.
[0030]
12 is a perspective view showing a conventional short prevention structure using the insulating
spacer.
[0031]
13 is a cross-sectional view of an electromagnetic speaker using the structure shown in FIG.
[0032]
14 is a perspective view showing a conventional short prevention structure using an adhesive.
[0033]
15 is a cross-sectional view of an electromagnetic speaker according to the structure shown in
FIG.
[0034]
Explanation of sign
[0035]
28 yoke 30 coil 36 insulation film
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