JP2009296160

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DESCRIPTION JP2009296160
[PROBLEMS] To provide a small-sized and thin speaker with high mass productivity by utilizing
the characteristics of a plastic magnet which can be easily processed into a desired shape. A
speaker (1) includes a magnetic circuit (3), a vibration system (4) having a diaphragm (22)
attached to a voice coil (21), and a frame (2) supporting the magnetic circuit and vibration
system The magnetic circuit 3 is constituted by a plastic magnet 16 having a T-shaped cross
section and a yoke 10 continuously provided on the bottom side and the periphery of the plastic
magnet 16 and is a component of a magnetic circuit conventionally having a three-piece
structure. Increase the mass productivity of small and thin speakers by reducing the number of
points. [Selected figure] Figure 1
スピーカ
[0001]
The present invention relates to a small and thin speaker used for a mobile phone or the like.
[0002]
Conventionally, a speaker (a dynamic type speaker) using a plastic magnet for a magnetic circuit
is known, for example, in Patent Document 1 and the like.
However, in terms of the component configuration and assembly of the magnetic circuit, it was
the same as a speaker using a general (ferrite, alnico, rare earth, etc.) metal-based magnet. The
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magnetic circuit was assembled by bonding the magnet and the yoke and the three parts of the
pole piece regardless of the type of the magnet.
[0003]
JP 2000-32589 A
[0004]
In the conventional speaker, the effect of the adhesive used for assembling the magnetic circuit is
so large that there is a problem that it is difficult to improve mass productivity.
[0005]
The present invention has been made in view of the above problems, and an object thereof is to
provide a small-sized and thin speaker with high mass productivity by utilizing the characteristics
of a plastic magnet which can be easily processed into a desired shape.
[0006]
In order to achieve the above object, the present invention is a speaker comprising a magnetic
circuit, a vibration system in which a diaphragm is attached to a voice coil, a frame supporting
the magnetic circuit and the vibration system, and the voice coil disposed in a magnetic gap The
magnetic circuit is constituted by a plastic magnet having a T-shaped cross section and a yoke
continuously provided on the bottom side and the periphery of the plastic magnet, and the
magnet itself has a role of three pieces. A two-piece structure of the magnetic circuit which was
conventionally a three-piece structure, that is, the number of parts, while using a larger volume
magnet for space saving and increasing the driving force of the voice coil compared to the
conventional magnetic circuit of the structure. To reduce.
[0007]
In the present invention, preferably, the top surface of the plastic magnet is formed to be
concave, and the central portion of the diaphragm is formed to be an inverted dome.
[0008]
In the present invention, a cylindrical portion raised by burring from a yoke on the bottom side
of the plastic magnet and a through hole for penetrating the cylindrical portion to the central
portion of the plastic magnet are provided, and the plastic magnet is used as the cylindrical
portion. It is preferable to connect with the said yoke by crushing the front-end ¦ tip part of.
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[0009]
According to the present invention, since the magnetic circuit is constituted by the plastic magnet
having a T-shaped cross section and the yoke continuously provided on the bottom side and the
periphery of the plastic magnet, The reduction can improve the mass productivity of small and
thin speakers.
[0010]
In the present invention, since the top surface of the plastic magnet is formed in a concave shape
and the central portion of the diaphragm is formed in an inverted dome shape, sufficient
amplitude of the vibration system is secured, and the acoustic performance is not deteriorated. It
is possible to realize further thinning of the thin speaker.
[0011]
In the present invention, a cylindrical portion raised by burring from a yoke on the bottom side
of the plastic magnet and a through hole for penetrating the cylindrical portion to the central
portion of the plastic magnet are provided, and the plastic magnet is used as the cylindrical
portion. Since it is connected to the above-mentioned yoke by crushing the tip portion of the
above, it is not necessary to use an adhesive in the assembly of the magnetic circuit, and the
mass productivity of a small and thin speaker can be further enhanced.
[0012]
Hereinafter, embodiments of the present invention will be described based on the drawings.
FIG. 1 is a cross-sectional view of a speaker according to an embodiment of the present invention,
and FIG. 2 is a plan view in which a diaphragm of the speaker according to the embodiment of
the present invention is transparent.
[0013]
The speaker 1 shown in FIGS. 1 and 2 includes a yoke-integrated frame 2 made of a magnetic
material, a magnetic circuit 3, and a vibration system 4.
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[0014]
The frame 2 is formed in a low-profile bottomed cylindrical shape, and has a circular bottom
plate 5 and an outer wall 6 rising from the outer peripheral edge of the bottom plate 5.
A horizontal step surface 7 is provided on the outer wall 6, and the upper surface of the outer
wall 6 is formed larger in diameter than the lower portion by the step surface 7.
[0015]
From the bottom plate 5, a yoke sidewall 8 which is an inner wall opposite to the lower portion
of the outer wall 6 with a predetermined gap is raised, and a circular shape comprising the yoke
sidewall 8 and the central portion of the bottom plate 5 inside the yoke sidewall 8. The yoke
bottom plate 9 forms a bottomed cylindrical yoke 10 having a lower height than the frame 2.
[0016]
A pair of lead wire outlet holes 11 which cut out the yoke side wall 8 to the lower end are
provided at two right and left places of the yoke side wall 8, and a pair of circles for inserting
lead wire forming jigs on the bottom plate 5 on the bottom side of the lead wire drawing position.
A hole 12 is provided, and a pair of substantially semi-circular back sound holes 13 are formed in
the bottom plate 5 on the bottom side other than the lead wire extraction position, which is the
outside of the bottom plate 5 between the outer wall 6 and the yoke side wall 8 It is provided.
The upper rear sound hole 13 in FIG. 2 continuously opens the lower surface of the outer wall 6
and the step surface 7 from the bottom plate 5.
[0017]
On the back side of the step surface 7 opened in the upper rear sound hole 13 in FIG. 2, a
substantially semi-circular insulating terminal plate 14 whose inner peripheral edge is in contact
with the yoke side wall 8 is fixed. While attaching a pair of external connection terminals (not
shown) to the back side of the speaker 1, a pair of lead wire contact pad portions 15 electrically
connected to the external connection terminals are formed exposed on both end surfaces of the
terminal plate 14 The lead wire contact pad portion 15 is exposed to the inside of the frame 2
through the upper rear sound hole 13 of FIG.
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[0018]
The magnetic circuit 3 is composed of a plastic magnet 16 and a yoke 10.
[0019]
The plastic magnet 16 is formed in a cylindrical shape having an outer diameter slightly smaller
than the inner diameter of the yoke side wall 8 at substantially the same height as the yoke side
wall 8 and concentrically disposed on the yoke bottom plate 9. The upper outer peripheral
surface of the plastic magnet 16 is opposed to the upper inner peripheral surface with the
magnetic gap 17 therebetween.
[0020]
Here, taking advantage of the property of the plastic magnet 16 that it can be easily processed
into a desired shape, the plastic magnet 16 is molded in a T-shaped cross section so that the
upper part has a larger diameter than the lower part.
As a result, the upper portion of the plastic magnet 16 is made closer to the yoke sidewall 8 than
the lower portion, and the magnetic flux is concentrated on the magnetic gap 17.
That is, the upper part of the plastic magnet 16 serves as a pole piece, uses a magnet of larger
volume in a space saving space as compared with the conventional magnetic circuit of the threepiece structure, and enhances the driving force of the voice coil 21 described later. The two-piece
structure of the magnetic circuit, which has conventionally been a three-piece structure, is to
reduce the number of parts.
[0021]
Further, the top surface (upper surface) of the plastic magnet 16 is formed not as a flat surface
but as a reverse dome-shaped concave surface 18 in order to realize the further thinning of the
speaker 1.
[0022]
Further, in order to connect the plastic magnet 16 and the yoke 10 without using an adhesive, a
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circular through hole 19 vertically penetrating at the center of the plastic magnet 16 is provided,
while the center of the yoke bottom plate 9 is burred. When the cylindrical portion 20 is raised
and the plastic magnet 16 is mounted on the yoke 10, the cylindrical portion 20 is fitted into the
through hole 19 from the lower side, and the tip of the cylindrical portion 20 is the concave 18
of the plastic magnet 16. The plastic magnet 16 and the yoke 10 are integrally integrated by
projecting upward at the central portion (the deepest portion) and crushing the tip of the
cylindrical portion 20.
[0023]
The vibration system 4 comprises a voice coil 21 formed by winding a conductive wire around a
cylindrical voice coil bobbin made of metal or plastic film, and a film made of metal or plastic,
and is stuck concentrically on the voice coil 21 It comprises a circular diaphragm 22.
[0024]
Here, in order to realize further thinning of the speaker 1, the diaphragm 22 is formed in a
reverse dome shape which bulges downward instead of a dome shape in which a central portion
inside the bonding position of the voice coil 21 bulges upward.
[0025]
Then, the outer peripheral edge portion back surface of the annular edge portion 24 around the
inverted dome portion 23 of the diaphragm 22 is a step surface 7 of the outer wall 6 at the outer
portion of the frame 2 through the diaphragm ring 25 having an L-shaped cross section. The
voice coil 21 is disposed within the magnetic gap 17 of the magnetic circuit 3 so as to be
vertically movable.
[0026]
The lead wire 26 drawn from the winding start end and the winding end of the voice coil 21 is
drawn from the lead wire outlet 11 to the outside of the yoke 10 and inserted from the lower
side of the frame 2 through the circular hole 12 into the lead wire drawing position Is hooked
into a round bar-like forming jig and bent into a substantially U-shape (forming) and is led to the
lead wire contact pad portion 15 to be connected, and the tip of the lead wire 26 is spot welded
to lead wire contact to be connected It is connected to the pad unit 15.
[0027]
In the speaker 1 configured as described above, when an audio signal is input to the voice coil 21
from the external circuit through the pair of external connection terminals, the magnetic field
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generated in the magnetic circuit 3 and the current flowing in the voice coil 21 By operation, the
voice coil 21 vibrates up and down, and the surrounding air is vibrated by the diaphragm 22
vibrating up and down in conjunction with it, and a sound is produced.
[0028]
At this time, since the magnetic circuit 3 is constituted by the plastic magnet 16 having a Tshaped cross section and the yoke 10 continuously provided on the bottom side and the
periphery of the plastic magnet 16, The reduction can improve the mass productivity of small
and thin speakers.
[0029]
In addition, since the top surface of the plastic magnet 16 is formed into the concave surface 18
and the central portion of the diaphragm 22 is formed into an inverted dome shape, a sufficient
amplitude of the vibration system 4 is ensured, and the acoustic performance is not deteriorated.
-It is possible to realize further thinning of thin speakers.
[0030]
Furthermore, a cylindrical portion 20 raised by burring from the yoke 10 on the bottom side of
the plastic magnet 16 and a through hole 19 for allowing the cylindrical portion 20 to penetrate
through the central portion of the plastic magnet 16 are provided. Since the front end portion of
20 is bonded to the yoke 10 by crushing, it is not necessary to use an adhesive for assembling
the magnetic circuit 3, and the mass productivity of small and thin speakers can be further
enhanced.
[0031]
Although the embodiment of the present invention has been described using the round speaker 1
in the present embodiment, it may be a square speaker.
The present invention is not limited to the present embodiment, and various modifications can be
made without departing from the scope of the invention.
[0032]
Cross-sectional view of a speaker according to an embodiment of the present invention A plan
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view of a state in which the diaphragm of the speaker according to an embodiment of the present
invention is transparent
Explanation of sign
[0033]
Reference Signs List 1 speaker 2 frame 3 magnetic circuit 4 vibration system 10 yoke 16 plastic
magnet 17 magnetic gap 18 concave 19 through hole 20 tube portion 21 voice coil 22
diaphragm 23 reverse dome portion
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