Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electromagnetic
Reexamination Certificate
2001-03-23
2004-12-28
Le, Huyen (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electromagnetic
C381S420000, C381S403000, C381S405000
Reexamination Certificate
active
06836551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin loudspeaker having a relatively low profile.
2. Description of the Related Art
A loudspeaker structure is disclosed in Japanese Laid-Open Patent Publication No. 55-64500, which includes a yoke having slits formed therein, and support members inserted in the slits, such that a voice coil and a diaphragm are coupled via the support members.
FIG. 39
is a cross-sectional view illustrating a conventional loudspeaker
7000
disclosed in Japanese Laid-Open Patent Publication No. 55-64500.
FIG. 40
is a plan view illustrating a magnetic circuit and associated elements, as viewed from above a diaphragm
8
of the loudspeaker
7000
.
The loudspeaker
7000
includes: a bottom plate
23
; a magnet
1
provided on the bottom plate
23
; a center pole
2
provided on the magnetic
1
; a yoke
3
which is provided so as to surround the center pole
2
and which has a plurality of slits
11
in a radial arrangement; a coupling member
37
; a voice coil
39
affixed to the inner periphery of the coupling member
37
; a diaphragm
8
and dampers
10
affixed to the outer periphery of the coupling member
37
; frames
12
A and
12
B; and a cover
34
. The coupling member
37
has support members
35
to be inserted in the plurality of slits
11
, and inner and outer rings
36
and
46
.
The magnet
1
, the center pole
2
, the yoke
3
, and the bottom plate
23
together compose a magnetic circuit. A magnetic flux is generated within a magnetic gap
4
by the magnetic circuit.
As an electric input is supplied to the voice coil
39
in the above structure, a driving force along a vertical direction is generated in the voice coil
39
according to Fleming's left-hand rule, due to the magnetic flux generated within the magnetic gap
4
. Since the diaphragm
8
is coupled to the voice coil
39
by means of the coupling member
37
(i.e., via the support members
35
), the driving force generated in the voice coil
39
is transmitted to the diaphragm
8
, which vibrates and emits sound. Since this structure prevents the diaphragm
8
from contacting an upper face
3
A of the yoke
3
, there is no need to allow for an amplitude margin when designing the total height of the loudspeaker
7000
. As a result, the total height h can be reduced.
FIG. 41
is a plan view showing a cylindrical coupling member
47
disclosed in Japanese Laid-Open Patent Publication No. 55-64500, supra. The cylindrical coupling member
47
is composed of an elongated metal foil which is folded at periodic lengths, so that the folded portions are linked together to form protruding support members
45
of the cylindrical coupling member
47
. A voice coil
39
is affixed to the inner periphery of the coupling member
47
.
However, in accordance with the loudspeaker
7000
shown in
FIGS. 39 and 40
, it is necessary to attach the coupling member
37
to the outer periphery of the voice coil
39
. As the wire diameter for the voice coil
39
is changed in order to obtain various levels of driving force, the outer diameter of the voice coil
39
also varies. This necessitates a change in the inner diameter of the inner periphery of the coupling member
37
to which the voice coil
39
is attached. In other words, for each voice coil
39
, a coupling member
37
having corresponding geometry must be designed. This presents a problem, when mass producing various models, in that costs associated with the production of component parts and the production facility itself are increased, and that the storage and management of varying component parts becomes cumbersome.
On the other hand, in the case where the coupling member
47
with support members
45
as shown in
FIG. 41
is formed by folding a thin metal foil (especially due to mass productivity-related concerns), the support members
45
can only be adhered to the diaphragm
8
and the dampers
10
in an extremely small adhesion area, resulting in a poor adhesion strength. Consequently, peeling associated with the diaphragm
8
moving with a large amplitude or failure of the driving force generated in the voice coil
39
to be transmitted to the diaphragm
8
may occur, thereby unfavorably affecting the sound pressure characteristics of the loudspeaker
7000
.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a loudspeaker including: a bottom plate; a center pole provided upwardly from the bottom plate; a yoke surrounding the center pole and having a plurality of slits; a magnet for providing a magnetic flux for the center pole and the yoke; a coil provided between the center pole and the yoke; a first annular member for supporting the coil; a plurality of support members for supporting the first annular member, the plurality of support members being inserted into the plurality of slits; and a diaphragm supported by the plurality of support members, wherein upper faces of the plurality of support members gradually decrease in height in a direction away from the first annular member, and wherein a lower face of the coil is located below a position at which the diaphragm is supported by the plurality of support members.
In one embodiment of the invention, the lower face of the coil is located below lower faces of the plurality of support members.
In another embodiment of the invention, the coil is provided at an outer periphery of the first annular member.
In still another embodiment of the invention, the loudspeaker further includes a plurality of dampers for supporting the plurality of support members.
In still another embodiment of the invention, the plurality of support members each have a plate-like shape.
In still another embodiment of the invention, the loudspeaker further includes a second annular member provided between the plurality of support members and the first annular member, wherein the plurality of support members support the first annular member via the second annular member.
In still another embodiment of the invention, the plurality of support members and the first annular member are formed as an integral piece.
In still another embodiment of the invention, the plurality of support members and the second annular member are formed as an integral piece.
In still another embodiment of the invention, the loudspeaker further includes a third annular member provided between the plurality of support members and the diaphragm, wherein the plurality of support members support the diaphragm via the third annular member.
In still another embodiment of the invention, the loudspeaker further includes a third annular member provided between the plurality of support members and the plurality of dampers, wherein the plurality of dampers support the plurality of support members via the third annular member.
In still another embodiment of the invention, the plurality of support members and the third annular member are formed as an integral piece.
In still another embodiment of the invention, the loudspeaker further includes a second annular member provided between the plurality of support members and the first annular member, wherein the plurality of support members support the first annular member via the second annular member.
In still another embodiment of the invention, the magnet is provided between the bottom plate and the center pole.
In still another embodiment of the invention, the bottom plate and the yoke are formed as an integral piece.
In still another embodiment of the invention, the magnet surrounds the center pole.
In still another embodiment of the invention, the magnet has a plurality of slits; and the plurality of slits of the magnet are disposed so as to be aligned with the plurality of slits of the yoke.
In still another embodiment of the invention, the bottom plate and the center pole are formed as an integral piece.
In still another embodiment of the invention, the first annular member is supported at a first end of each of the plurality of support members, and the diaphragm is supported at a second end of each of the plurality of su
Koura Satoshi
Kuze Mitsukazu
Saiki Shuji
Takewa Hiroyuki
Le Huyen
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
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