JP2004289772

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DESCRIPTION JP2004289772
An object of the present invention is to provide a panel type speaker which can realize
miniaturization of the entire display apparatus including a frame of a peripheral portion when
combined with a thin display apparatus such as a liquid crystal panel. A panel-type speaker
according to the present invention includes a magnetic circuit, a voice coil (V), and a bobbin (B)
for holding the voice coil. The exciter is disposed at both left and right or upper and lower end
portions of a thin display device. (E) and a speaker of a vibration mode system provided with a
translucent flat plate which is disposed on the front surface of the thin display device and which
is also excited by the exciter to generate flexural vibration. Each exciter (E) is composed of a
plurality of exciters (e, e, e) disposed adjacent to each other in the vertical direction or in the left
or right direction of the thin display device and connected in parallel. [Selected figure] Figure 2
Panel type speaker
The present invention relates to a vibration mode (DM) type panel type speaker, and more
particularly to a panel type speaker suitable for thin display devices such as liquid crystal and
plasma. . [0002] The applicant has already filed several patent applications for vibration mode
(DM) type panel speakers (Patent Documents 1, 2 and 3). In this vibration mode speaker, the tip
of the bobbin holding the exciter's voice coil is attached to the back of a flat plate (panel) whose
peripheral part is fixed via a soft elastic body, and the exciter's magnetic circuit is used as an
elastic body. It has a structure fixed to a case etc. The reciprocating motion of the bobbin excites
bending vibration in the panel to which the tip is fixed. This type of sound generation system is
referred to as a distributed mode (DM) system or a vibration mode system because the flexural
vibration is mainly used for sound generation rather than the back and forth reciprocation of the
panel. The advantage of this vibration mode type panel speaker is that high sound quality and a
thin structure can be realized. Furthermore, the present applicant has already filed a patent
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application for a panel type speaker suitable for combination with a thin display device such as a
liquid crystal panel or a plasma panel (Patent Document 4). This panel type speaker is configured
such that a light transmitting flat plate (panel) such as a protective cover or a polarizing filter
disposed on the front surface of a thin display device is also used as a diaphragm of a panel type
speaker of a vibration mode (DM) method. It is done. [Patent Document 1] Japanese Patent
Application Laid-Open No. 10-243491 (FIGS. 1 to 3) [Patent Document 2] Japanese Patent
Application Laid-Open No. 11-331966 (FIGS. 1 to 2) [Patent Document 3] Japanese Patent
Application Laid-Open No. 11- 331969 (FIGS. 1 to 3) [Patent Document 4] JP 2001-189978
(FIGS. 1 to 5). SUMMARY OF THE INVENTION In the vibration mode panel speaker disclosed in
Patent Document 4, a small exciter is disposed between the main body of the liquid crystal panel
or plasma panel and the left and right frames. ing. In this structure, the width of the entire
display including the frame is determined by the size of the exciter of the panel type speaker. As
a result, in order to miniaturize the entire display apparatus including the outer frame, there is a
need for an exciter configuration and arrangement that can further reduce the width of the left
and right and upper and lower sides thereof.
Accordingly, it is an object of the present invention to realize such an exciter configuration and
arrangement. SUMMARY OF THE INVENTION A panel-type speaker according to the present
invention for solving the above-mentioned problems of the prior art comprises a magnetic circuit,
a voice coil, and a bobbin for holding the voice coil. Alternatively, a vibration mode system is
provided that includes exciters disposed at upper and lower end portions and a translucent flat
plate which is disposed on the front surface of the thin display device and is also excited by the
exciter to generate flexural vibration. It is a panel type speaker. The exciters disposed at the left
and right or upper and lower end portions of the thin display device are constituted by a plurality
of small exciters arranged adjacent to and connected in parallel in the vertical or horizontal
direction of the thin display device. The distance between the left and right or upper and lower
end portions of the mold display device and the frame outside thereof is reduced. According to a
preferred embodiment of the present invention, the tip end portions of the bobbins of the
plurality of small exciters are connected by a connecting member, whereby the displacement
amount of each exciter and the amount of displacement of each exciter are obtained. It is
configured to ensure parallel operation regarding timing. According to another preferred
embodiment of the present invention, the connecting member or the tip portion of the bobbin
connected by the connecting member and the light transmitting flat plate disposed on the front
surface of the thin display device are a vibration transmitting member. The connection between
the exciter and the flat plate is facilitated by being connected by According to still another
preferred embodiment of the present invention, the connection portion between the tip end
portion of the connection member or the bobbin connected thereto and the vibration transfer
member is a flat plate transparent to the vibration transfer member. The vibration transmitting
member is bent so as to be positioned at the central portion of the thin display device than the
connecting portion with, further shortening the distance between the left and right or upper and
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lower end portions of the thin display device and the frame outside thereof. Are configured to
FIG. 1 is a perspective view showing a structure of an exciter which constitutes a panel type
speaker according to an embodiment of the present invention, together with a method of
assembling the same. In this exciter, first, small exciters e1, e2 and e3 are press-fit into the
respective openings of the holding plate S made of resin, in which three openings are formed
adjacent to each other, as shown in FIG. Thus, three small exciters are arranged adjacent to one
another. Each of the small exciters e1, e2 and e3 represents a permanent magnet and a magnetic
circuit M comprising inner and outer yokes which hold the air gap to form a space and a bobbin
B which holds a voice coil, as represented by e1. And have.
Next, as shown in FIG. 6B, the tip portions of the bobbins B of the exciters e1, e2 and e3 are
connected by a connecting plate C. Although the tip portion of each small exciter bobbin B is not
shown by a dotted line because the connecting plate C is transparent, the tip portion of each
bobbin exists behind the connecting plate C. Finally, as shown in FIG. 7C, a truncated coneshaped vibration transmitting member t is bonded and fixed to the tip end surface of the bobbin
B of the exciter e2 in the middle, and the exciter E is completed. FIG. 2A is a plan view (partial
cross-sectional view) showing the configuration of a panel type speaker including an exciter E
consisting of three small exciters shown in FIG. 1C together with a liquid crystal panel. An exciter
E is mounted between the left and right end portions of the liquid crystal panel L and a frame F
surrounding the liquid crystal panel L at a central portion in the vertical direction of the liquid
crystal panel L. Only the exciter E on the right side is shown in the figure (A). The three small
exciters e1, e2 and e3 constituting the exciter E are vertically arrayed in the central portion of
the right side surface of the liquid crystal panel L. A protective cover disposed in front of the
liquid crystal panel L is fixed to the frame F as a translucent flat plate P via a cushion c 1 made of
a soft elastic member. The holding plate S of the exciter E is fixed to the frame F via a cushion c2
also made of a softer elastic member. The tip end portion of the vibration transfer member t
shown in FIG. 1C is adhesively fixed to the back surface of the translucent flat plate P also
serving as the diaphragm. The small exciters e1, e2 and e3 constituting the exciter E are
electrically connected in parallel. That is, an electric signal of the same amplitude and phase is
supplied to the voice coil of each small exciter. The bobbin holding the voice coil of each small
exciter vibrates back and forth with the same amplitude and timing, also due to the restraint by
the connecting plate C. This vibration is transmitted through the vibration transmitting member t
to the translucent flat plate P disposed in front of the liquid crystal panel L, and generates a front
and back vibration and a bending vibration of energy larger than this. That is, the translucent flat
plate P operates as a diaphragm of the panel type speaker. FIG. 2B is a plan view (partially
sectional view) showing the configuration of a conventional panel-type speaker in order to
compare it with the configuration of the above embodiment. In this panel type speaker, the
exciters disposed on the left and right sides of the liquid crystal panel L are made up of one
exciter E. As this one exciter E must generate the same vibrational energy as the three small
exciters in the above-described embodiment of the present invention, its size is increased.
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As a result, as shown in comparison with FIGS. 2A and 2B, the width of the frame is increased by
W than that of the above embodiment, and the entire liquid crystal display device provided with
the panel type speaker is so large. become. FIG. 3 is a plan view (partially sectional view) showing
the configuration of a panel type speaker according to another embodiment of the present
invention together with a liquid crystal display device. In this figure, the components given the
same reference numerals as in FIG. 2 are the same as the components described above with
reference to FIG. In this embodiment, an exciter E consisting of three small exciters e1, e2 and e3
as shown in FIG. 1B is attached to an L-axis bracket U fixed to the back surface of the liquid
crystal panel L via a cushion C2. It is attached. The vibration transfer member t is not a truncated
cone as shown in FIG. 1C, but is divided into two parts t1 and t2 fitted together, and one part t1
is bent doing. As a result, the connection portion between the tip portion of the bobbin B of the
small exciter e2 and the vibration transfer member t is disposed at the central portion of the
liquid crystal panel L rather than the connection portion between the vibration transfer member t
and the translucent flat plate P. Ru. By this configuration, the distance between the end portions
of the liquid crystal panel L and the frame F outside thereof is further shortened. D is a cloth
damper. FIG. 4 changes the material of the holding plate S made of resin in the embodiment
shown in FIG. 1 to a metal having good thermal conductivity, and at the same time, the holding
plate S and the metallic casing of the liquid crystal display device. This embodiment is an
embodiment in which a metal foil T is bonded to a metal plate U connected to a body, a frame or
the like. The small exciters e1, e2 and e3 have good heat conduction to the holding plate S by the
respective yokes being pressed into the circular openings formed adjacent to the metal holding
plate S. Hold while holding. The heat generation of each small exciter is transferred to the metal
case, frame, shield plate, etc. of the liquid crystal display through the heat conduction path of
metal holding plate S → metal foil T → metal plate U and heat is released. . In this type of small
exciter, the heat generation density tends to further increase due to the combination of recent
miniaturization and high output. As a result, the temperature of the magnetic circuit of the
exciter rises, and there is a possibility that the magnetic characteristics necessary for achieving
good electrical / mechanical conversion characteristics may deteriorate. In this embodiment, the
material of the holding plate S is metal, and by forming a heat radiation path from the holding
plate to the outside, the temperature rise of the small exciter can be suppressed and good
magnetic characteristics can be ensured.
In order to allow the holding plate S to vibrate, a flexible metal foil T is used. As a material of the
holding plate S, the metal foil T and the metal plate U, aluminum alloy, copper or the like can be
used. Instead of the metal foil T or the metal plate U, a flexible electric wire or conductive rubber
can be used. The connection of each part can be realized by a thermally conductive adhesive. The
outer circumferential surface of the yoke of the small exciter divided into three pieces than the
area of the contact surface between the outer circumferential surface of the single large exciter
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yoke and the opening of the metal holding plate S into which the single large exciter is pressed.
The area of the sum of the contact surfaces with the small openings of the metal holding plates S
into which the respective members are press-fitted is increased, and the heat is efficiently
dissipated. That is, let D be the diameter of a large exciter and d be the diameter of a small
exciter. Assuming that the size of the audio output is proportional to the cross-sectional area of
each exciter, the output of a single large exciter and the output of three small exciters is equal to
D <2> = 3d <2>, that is, D = 3 <1/2> d. Assuming that the contact area between each exciter and
the holding plate is proportional to the length of the outer periphery, the contact area A∞D of a
single exciter and the total contact area of 3 small exciters is 3a = 3d. From this, 3a / A = 3d / D =
3 <1/2> ≒ 1.73 is obtained. As described above, the configuration of the present invention in
which a single large exciter is divided into a plurality of small exciters is effective not only in the
downsizing of the entire apparatus but also in the efficiency of heat dissipation. The
configuration in which the tip end surface of the bobbin of each small exciter is disposed at the
rear of the connecting member has been described above. However, the tip of the bobbin may be
protruded forward from the connecting member, and the vibration transmitting member may be
fixed to the tip of the protruding bobbin. In addition, while the tips of the bobbins of the three
exciters are connected by the connecting member, the configuration in which the vibrations
generated by the exciters are transmitted to the flat plate via the vibration transmitting members
is exemplified. However, the vibration transmission member may be omitted, and a configuration
in which the connection member is directly fixed to a flat plate may be employed. Further, the
connecting member may be omitted, and the tip of the bobbin of each exciter may be directly
fixed to a flat plate. Furthermore, although the case where the number of small exciters is three
has been exemplified, an appropriate number such as two or four or more may be adopted.
Furthermore, the configuration in which the heat radiation path is formed from the metal holding
plate S to the outside through the metal foil, the wire, and the like is illustrated.
However, without forming a heat dissipation path from the holding plate to the outside, heat can
be dissipated directly from the holding plate by convection. It is also possible to adopt a
configuration in which the effect of heat dissipation is enhanced by forming the heat dissipating
fins on the holding plate S. As described above in detail, the panel-type speaker according to the
present invention is constituted by a plurality of small exciters connected in parallel and
connected with voice coils. The distance between both end portions of the frame and the frame
outside thereof is shortened, and the entire thin display apparatus including the frame outside
and the panel type speaker can be miniaturized. According to one embodiment of the present
invention, the vibration transmitting member is bent, thereby achieving further miniaturization of
the thin display device including the frame. The adoption of the panel-type speaker according to
the present invention enables the reduction in size of a thin display device, which has the
advantage of increasing the degree of freedom in its design. According to a preferred
embodiment of the present invention, the small exciter is formed by arranging a plurality of small
exciters adjacent to a metal holding plate or forming a heat radiation path from the holding plate.
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Since the heat generated is dissipated, temperature rise of the exciter can be prevented and
performance can be maintained by good magnetic characteristics under downsizing and high
power. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the
structure and assembling method of an exciter constituting a panel type speaker according to an
embodiment of the present invention. FIG. 2 is a plan view (partial cross-sectional view) showing
a configuration of a panel type speaker (A) according to an embodiment of the present invention
in comparison with a configuration of a conventional panel type speaker (B). FIG. 3 is a plan view
(partially sectional view) showing a configuration of a panel type speaker according to another
embodiment of the present invention. FIG. 4 is a perspective view showing a configuration of a
panel type speaker according to still another embodiment of the present invention. Explanation
of symbols E Exciter e1, e2, e3 Small exciter B Bobbin holding voice coil M Magnetic circuit C
Connecting member t, t1, t2 Vibration transmission member P Translucent flat plate L serving as
diaphragm L Liquid crystal panel F Frame C1, C2 cushion S holding plate T metal foil U metal
plate
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