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JPH0879890

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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 JPH0879890
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
movable iron type speaker. There is a movable iron-piece type speaker which is small and thin
and used for a telephone receiver or a portable OA device, and which drives a diaphragm by an
electromagnetic force acting on a soft magnetic material. This movable iron type speaker is
widely used for acoustics, and is inferior in sound quality and reproducible frequency band to an
electrodynamic speaker utilizing electromagnetic force acting on a movable coil placed in a
magnetic field. However, in this type, the movable part is only the soft magnetic iron piece and
the diaphragm, and the drive coil is on the stationary side, so the structure is simple, the
durability is high, and a small size and a small size are required. It is used as a sound generator
for office automation equipment. In recent years, along with the development of multimedia
equipment in office automation equipment and the improvement of the sound quality of
telephones, it has been desired to miniaturize and improve the sound quality and the
reproducible frequency band while providing the features of the movable iron type speaker.
[0002]
2. Description of the Related Art A conventional movable iron type speaker is constituted by
parts as shown in, for example, (a) to (e) of FIG. A drive coil 33 is wound on a salient pole 32
provided on the soft magnetic magnetic circuit 31. An annular annular permanent magnet 34
magnetized in the thickness direction of the annular ring is disposed outside the drive coil 33.
Furthermore, a nonmagnetic spacer 35 is provided on the outside, and a diaphragm 36 of soft
magnetic soft plate and movable iron piece 37 are assembled to the spacer 35, and the gap size
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between the movable iron piece 37 and the salient pole 32 is appropriate. A spacer 35 holds the
outer periphery of the diaphragm 36 at an interval.
[0003]
FIG. 5 shows a cross-sectional view and a top view of a movable iron-piece type speaker
assembled as described in FIG. The magnetic flux generated from the permanent magnet 34
forms a loop through the movable iron piece 37-salient pole 32-magnetic circuit 31 to generate
an electromagnetic force that attracts the movable iron piece 37 in the direction of the
permanent magnet 34 and the salient pole 32 . The diaphragm 36 to which the movable iron
pieces 37 are joined is assembled in a bent state as illustrated by the attraction force of the
electromagnetic force. When an alternating current corresponding to the voice signal is supplied
to the drive coil 33, the suction force acting between the movable iron piece 37 and the salient
pole 32 is increased or decreased, and the diaphragm 36 vibrates to generate a sound wave.
[0004]
As described above, in the movable iron type speaker, in order to obtain a large output with the
same drive current, it is necessary to make the magnetomotive force of the permanent magnet
34 stronger. When the magnetomotive force of the permanent magnet 34 is increased, the
attraction force for attracting the movable iron piece 37 is also increased by the permanent
magnet 34. As a result, the deformation of the diaphragm 36 holding the movable iron piece 37
becomes large, and the following problem occurs Do.
[0005]
(1) In a large deformation, the proportional relationship between the acting force and the
displacement deviates, and the distortion increases. (2) It becomes difficult to set the gap
between the movable iron piece 37 and the salient pole 32 correctly.
[0006]
(3) If the thickness of the diaphragm 36 is increased to reduce the deformation of the diaphragm
36, the problems of (1) and (2) can be reduced, but the displacement due to the attraction force
becomes smaller Sound output can not be obtained.
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[0007]
(4) Further, the vibration of the central portion of the diaphragm 36 provided with the movable
iron piece 37 is large and the peripheral portions are held so as not to vibrate, so that the
efficiency of outputting the sound wave is bad.
[0008]
In order to solve these problems, the present invention holds the outer peripheral portion of the
diaphragm with an elastic support and vibrates the whole of the diaphragm substantially
uniformly to increase the generation efficiency of the sound wave, and The object is to realize a
movable iron type speaker having a wide high frequency band.
[0009]
Means for Solving the Problems The means for solving the problems will be described with
reference to FIGS. 1 and 3. FIG.
In FIGS. 1 and 3, the movable iron piece 1 vibrates when a current is caused to flow through the
drive coil 7 to generate a magnetic flux, and the movable iron piece 1 is joined to the diaphragm
2.
[0010]
The diaphragm 2 is such that the movable iron piece 1 is joined and vibrates uniformly to
generate sound, and the outer peripheral portion is held by the elastic support 3.
The elastic support 3 holds the outer peripheral portion so that the entire diaphragm 2 vibrates
substantially uniformly.
[0011]
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The salient pole 4 is for providing a predetermined gap between the movable iron piece 1 and
the magnetic circuit 5.
The magnetic circuit 5 is a magnetic circuit for forming a magnetic loop between the permanent
magnet 6, the movable iron piece 1, and the salient pole 4.
[0012]
The permanent magnet 6 generates a magnetic flux in the movable iron piece 1, the salient pole
4 and the loop forming the magnetic circuit 5. The drive coil 7 changes the magnetic flux in the
magnetic loop generated by the movable iron piece 1, the salient pole 4, the magnetic circuit 5,
and the permanent magnet 6 to vibrate the movable iron piece 1.
[0013]
The spacer 8 is a nonmagnetic material, and holds the diaphragm 1 at a predetermined position
via the elastic support 3. The reinforcing portion 11 is for reinforcing when the diaphragm 2 is
made thin.
[0014]
According to the present invention, as shown in FIG. 1, a magnetic loop is formed by the
permanent magnet 6, the movable iron piece 1, the salient pole 4 and the magnetic circuit 5 by
the magnetic flux generated by the permanent magnet 6. A gap is provided in the magnetic loop,
and the movable iron piece 1 joined to the diaphragm 2 is held by the elastic support 3 in a state
where it can be uniformly vibrated. In this state, when an audio current is supplied to the drive
coil 7 to change the magnetic flux generated in the magnetic loop, the movable iron piece 1
vibrates, and this vibration causes the entire diaphragm 2 to vibrate substantially uniformly.
Sound is generated with high efficiency.
[0015]
At this time, the elastic support 3 is made of a ring of elastic material or a hollow ring, and the
whole is held by the outer peripheral portion of the diaphragm 2 so that the whole of the
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diaphragm 2 is vibrated substantially uniformly. ing.
[0016]
Further, the elastic support 3 is made of a ring of elastic material, a hollow ring or a spiral coil,
and a plurality of points on the outer peripheral portion of the diaphragm 2 are held to make the
whole of the diaphragm 2 substantially uniform. It is made to vibrate.
[0017]
Further, as shown in FIG. 3, the diaphragm 2 is made thin, and a ring-shaped or rib-shaped
reinforcing portion 11 is provided to reinforce it.
Therefore, by holding the outer peripheral portion of the diaphragm 2 by the elastic support 3
and vibrating the whole diaphragm 2 substantially uniformly, the generation efficiency of the
sound wave is enhanced, and the small size and the high frequency band are expanded. It has
become possible to realize a movable iron type speaker.
[0018]
Next, the configuration and operation of the embodiment of the present invention will be
sequentially described in detail with reference to FIGS. 1 to 3. FIG.
[0019]
FIG. 1 shows a block diagram of one embodiment of the present invention.
(A) of FIG. 1 shows a cross-sectional view, and (b) to (g) of FIG. 1 show an example of an elastic
support.
[0020]
In FIG. 1A, the movable iron piece 1 is a ring-shaped thin plate of soft iron, and is joined to the
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diaphragm 2.
When a voice current flows through the drive coil 7, the movable iron piece 1 changes the
magnetic flux, and the movable iron piece 1 vibrates. Along with the vibration of the movable
iron piece 1, the whole of the diaphragm 2 joined is vibrated almost uniformly, and the sound is
generated with high efficiency.
[0021]
The diaphragm 2 has an outer peripheral portion held by an elastic support 3 and vibrates
substantially uniformly throughout. The ring-shaped movable iron piece 1 is joined near the
center, and the movable iron piece 1 is When vibrating in accordance with the audio current, the
whole of the diaphragm 2 vibrates substantially uniformly to generate a sound.
[0022]
The elastic support 3 holds the vibrating plate 2 which vibrates substantially uniformly at the
outer peripheral portion, and is a ring of an elastic body such as rubber (see (b) to (g) in FIG. 1).
reference).
The salient pole 4 is for providing a gap in the magnetic loop so that the movable iron piece 1
can be inserted.
[0023]
The magnetic circuit 5 is for forming a closed loop with the movable iron piece 1, the salient pole
4 and the magnetic circuit 5 with respect to the magnetic flux generated by the permanent
magnet 6 and the drive coil 7.
[0024]
The permanent magnet 6 generates a magnetic flux in a magnetic loop composed of the movable
iron piece 1, the salient pole 4 and the magnetic circuit 5.
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The drive coil 7 causes a voice current to flow to fluctuate the magnetic flux generated by the
permanent magnet 6 to vibrate the movable iron piece 1.
[0025]
The spacer 8 is a nonmagnetic spacer which holds the movable iron piece 1 joined to the
diaphragm 2 through the elastic support 3 in a predetermined position so as not to contact the
salient pole 4 in the gap of the magnetic loop.
[0026]
FIG. 1 (b) shows an example of a ring-like elastic support.
This is an elastic support 3 made of a ring-like elastic body (for example, rubber), which is placed
on the portion of the spacer 8 in (a) of FIG. 1, and the diaphragm 2 is placed thereon. When the
movable iron piece 1 joined to the diaphragm 2 vibrates, the whole of the diaphragm 2 vibrates
as dotted lines in FIG. 2 described later due to the vibration at the portion of the elastic support 3
in the outer peripheral portion of the diaphragm 2 Sound is generated from the whole of the
diaphragm 2 and sound can be generated with high efficiency.
[0027]
FIG. 1 (c) shows an example of the cross-sectional shape of the elastic support of FIG. 1 (b). As
the cross-sectional shape, as shown in the figure, it is formed from a polygon or circle consisting
of a rectangle, a triangle, a circle and the like. Also, in the case of hollow, as shown in the figure,
it is made hollow or square like rectangular hollow, triangular hollow, cylinder, square, etc., and
the diaphragm 2 is placed on the elastic support 3 Makes it easy to vibrate.
[0028]
FIG. 1 (d) shows an example of an elastic support cut in a ring shape. In this case, since the shape
of the ring-like elastic support is not fixed, it can be easily inserted into the groove portion of the
spacer 8 in FIG. 1 (a). The cross-sectional shape is the same as (c) of FIG.
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[0029]
FIG. 1 (e) shows an example of a corrugated washer-like elastic support. This is obtained by
cutting a thin spring material into a ring and then forming it into a wave. FIG. 1 (f) shows an
example of an elastic support in which a spring is extended to form a ring. This is an elastic
support in which a spring is extended to be in a ring shape as shown in the enlarged view of (f-1)
in FIG. 1, and the dotted line indicates the contact point with the diaphragm 2. Thus, the elastic
support 3 is formed by stretching the spring into a ring to form the elastic support 3 and using a
good spring material, which is convenient for causing the entire diaphragm 2 to vibrate
substantially uniformly. Can create
[0030]
FIG. 1G shows an example in which the spring is used as an elastic support as it is. In this case, a
spring in which a coil is wound with the size of the outer peripheral portion of the diaphragm 2
is formed, and is used as the elastic support 3.
[0031]
Next, the operation of the configuration of FIG. 1 will be described. (1) In the assembled state as
shown in (a) of FIG. 1, the magnetic flux generated by the permanent magnet 6 forms a closed
loop through the movable iron piece 1, the salient pole 4 and the magnetic circuit 5, and the
movable iron piece 1 Is attracted in the direction of the salient pole 2 and the permanent magnet
6, and the outer peripheral portion of the diaphragm 2 joined with the movable iron piece 1 is
held by the elastic support 3 inserted in the groove of the spacer 8.
[0032]
(2) When an audio current is supplied to the drive coil 7, a change in the generated magnetic flux
causes the attraction of the movable iron 1 to be attracted toward the salient pole 4 and the
permanent magnet 6 to fluctuate. When the movable iron piece 1 is displaced due to this
variation, the diaphragm 2 to which the movable iron piece 1 is joined vibrates at the elastic
support 3 and the whole diaphragm 2 vibrates substantially uniformly, so that sound waves are
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generated. Radiate. The vibration of the diaphragm 2 is such that the whole of the diaphragm 2
vibrates as shown by the dotted line in FIG. 2, so that the sound generation efficiency is
extremely good. In the conventional diaphragm, as shown by the solid line in FIG. 2, since the
outer periphery of the diaphragm is fixed, the central portion joined of the movable iron piece 1
vibrates, and the displacement gradually becomes smaller toward the outer periphery. Will be
completely zero in the department.
[0033]
As described above, in the movable iron type loudspeaker of the configuration of FIG. 1, the
diaphragm 2 can be vibrated substantially uniformly in its entirety by the elastic support 3 at the
outer peripheral portion of the diaphragm 2, so that high efficiency is achieved. It has become
possible to generate audio.
[0034]
FIG. 2 shows a conceptual view of displacement of the diaphragm of the present invention.
Here, the horizontal axis indicates the position of the cross section of the diaphragm 2, and the
vertical axis indicates the displacement of the diaphragm 2. The solid line shows the
displacement of the diaphragm when the outer peripheral part of the conventional diaphragm is
fixed, and the dotted line shows the diaphragm 2 when the outer peripheral part of the
diaphragm 2 of the present invention is held by the elastic support 3 in a vibratable state.
Indicates the amount of displacement of Here, the displacement amount of the movable iron
piece at the center of the diaphragm is the same.
[0035]
In the product of the present invention indicated by the dotted line, as shown in the figure, both
the central portion and the outer peripheral portion of the diaphragm 2 vibrate approximately
uniformly. This is vibrated by the movable iron piece 1 joined near the center of the diaphragm
2, and the outer peripheral portion of the diaphragm 2 is held by the elastic support 3 so that the
whole diaphragm 2 can be vibrated substantially uniformly. Since the entire area of the
diaphragm 2 vibrates as shown by the dotted line when it vibrates near the center of the
diaphragm 2, it is possible to emit the sound extremely efficiently.
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[0036]
On the other hand, in the conventional product of the solid line, as shown in the figure, the outer
peripheral part of the diaphragm 2 is fixed, so that the area around the center vibrates, but the
outer peripheral part has no vibration. For this reason, the sound generation efficiency of the
diaphragm 2 is not as good as that of the product of the present invention indicated by the
dotted line.
[0037]
FIG. 3 shows an example of reinforcement of the diaphragm of the present invention. This is an
example of reinforcing when the diaphragm 2 is made thin and light to increase its rigidity. (A) of
FIG. 3 shows the example which joined the ring-shaped reinforcement part 11 to the outer
peripheral part of a diaphragm. A flat ring-shaped movable iron piece 1 is provided in the vicinity
of the central portion of the diaphragm 2, and a flat ring-shaped reinforcing portion 11 is
provided on the outer peripheral portion. As a result, it is possible to reinforce the outer
peripheral portion in a state in which the diaphragm 2 is made thin and light, to make the whole
as light as possible to increase the rigidity, and to widen the frequency band to the wide side.
[0038]
FIG. 3 (b) shows an example in which a flat ring-shaped reinforcing portion 11 is joined to the
middle of the outer peripheral portion and the center of the diaphragm. A flat ring-shaped
movable iron piece 1 is provided in the vicinity of the central portion of the diaphragm 2, and a
flat ring-shaped reinforcing portion 11 is provided in the middle between the outer peripheral
portion and the center. As a result, it is possible to reinforce the middle portion in a state in
which the diaphragm 2 is made thin and light, and to make the whole as a whole to widen the
frequency band to the wide area side.
[0039]
FIG. 3C shows an example in which a flat ring-shaped reinforcing portion 11 is joined to the
outer peripheral portion and the middle portion of the diaphragm, respectively. A flat ring-
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shaped movable iron piece 1 is provided in the vicinity of the central portion of the diaphragm 2,
and flat ring-shaped reinforcing portions 11 are provided on the outer peripheral portion and the
middle portion respectively as illustrated. As a result, it is possible to reinforce the outer
peripheral portion and the intermediate portion in a state in which the diaphragm 2 is made
thinner and lighter, to make the whole as a whole lighter to increase the rigidity, and to widen
the frequency band to the wide area side.
[0040]
FIG. 3D shows an example in which a reinforcing portion and a rib-like reinforcing portion are
joined to the outer peripheral portion of the diaphragm. A flat ring-shaped movable iron piece 1
is provided in the vicinity of the central portion of the diaphragm 2, a flat ring-shaped reinforcing
portion 11 is provided on the outer peripheral portion, and both are bridged and joined by the
rib-shaped reinforcing portion 11. Thus, the movable iron piece 1 near the center and the
reinforcing portion 11 provided on the outer peripheral portion are connected by the rib-like
reinforcing portion 1 to form a framework as a whole, and a thin nonmagnetic thin film is
attached thereto It is possible to form the diaphragm 2 and to make the diaphragm 22 thinner
and lighter, and as a whole, it is possible to make the diaphragm 2 lighter as a whole to increase
the rigidity and to widen the frequency band to the wide area side.
[0041]
As described above, according to the present invention, a configuration is adopted in which the
outer peripheral portion of the diaphragm 2 is held by the elastic support 3 and the whole of the
diaphragm 2 is vibrated substantially uniformly. Because of this, it is possible to realize a
movable iron-piece type speaker in which the sound wave generation efficiency is enhanced, the
size is small, and the high frequency band is expanded to improve the sound quality. As a result,
(1) in the movable iron type speaker, the ratio of the output sound volume to the input signal can
be increased to greatly improve the efficiency.
[0042]
(2) Since the efficiency can be greatly improved in (1), the size can be reduced to obtain the same
output volume. (3) The weight reduction and rigidity of the diaphragm 2 can be enhanced, and
the frequency band can be expanded to the high frequency side to improve the sound quality.
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[0043]
Brief description of the drawings
[0044]
1 is a block diagram of one embodiment of the present invention.
[0045]
2 is a conceptual view of displacement of the diaphragm of the present invention.
[0046]
3 is an example of reinforcement of the diaphragm of the present invention.
[0047]
4 is an explanatory view (1) of the prior art.
[0048]
5 is an explanatory view (2) of the prior art.
[0049]
Explanation of sign
[0050]
1: movable iron piece 2: diaphragm 3: elastic support 4: salient pole 5: magnetic circuit 6:
permanent magnet 7: driving coil 8: spacer 11: reinforcement
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