JP2004343362

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DESCRIPTION JP2004343362
A flat speaker capable of stereo reproduction with a single diaphragm is provided. A diaphragm 2
is elastically supported via elastic supporting portions 4 a and 4 b provided on a display panel 3.
Drive means 10a and 10b are provided inside the elastic support parts 4a and 4b, and rigid
support parts 5a and 5b are provided inside the drive means 10a and 10b. When the drive
means 10a and 10b are driven to vibrate the diaphragm 2, each vibration is blocked by the rigid
support portions 5a and 5b, and the region of the diaphragm 2 in the region Q1 does not vibrate.
[Selected figure] Figure 2
Flat speaker
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
planar speaker capable of stereo reproduction, and more particularly to a planar speaker capable
of outputting sound individually with a sheet-like diaphragm. [0002] As a conventional flat
speaker, there is one shown in Patent Document 1 below. In this document, driving means
comprising a yoke, a magnet and a voice coil each formed thin on the back side of a diaphragm
provided on the surface is provided. The driving means are arranged at four places on the back
side of the diaphragm. When each voice coil is energized, the diaphragm is reciprocated in the
direction perpendicular to the surface to generate a sound. However, in the above-described
conventional flat speaker, when each driving means is driven to vibrate the diaphragm, the
above-mentioned conventional flat speaker is used. It was difficult for the sound pressure of each
other to mix, and to output each sound separately from a different position. For this reason, in
the case of stereo reproduction, it was necessary to separately provide and arrange the
diaphragms and to provide driving means to each diaphragm. Further, in the conventional flat
speaker, the drive means is provided to cover almost the entire back side of the diaphragm, so
the installation place is limited to the place where other members such as the operation member
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of the case are not incorporated. It was being done. An object of the present invention is to solve
the above-mentioned conventional problems, and it is an object of the present invention to
provide a flat speaker which can reproduce sound three-dimensionally and which is not limited in
installation location. SUMMARY OF THE INVENTION The present invention comprises a
diaphragm formed in a sheet shape provided on a base, and a plurality of drive means for
vibrating the diaphragm to generate sound pressure. The driving means are spaced apart from
each other by a predetermined distance in a direction along the vibration plane of the diaphragm,
and the driving means are divided between the base and the diaphragm to form the driving
means. A rigid support is configured to block or damp the vibration of the diaphragm when one
drive means is driven is transmitted to the diaphragm when the other drive means is driven It is
characterized in that it is provided. For example, in the diaphragm, a pair of driving means are
provided apart from each other in the direction along the vibrating surface, and a pair of the rigid
body support portions are provided at a predetermined interval opposite to each other of the
driving means. Sound pressure is individually generated outside the rigid support portions.
By providing the rigid support as described above, the sound pressure of the diaphragm vibrated
by one driving means is not mixed with the sound pressure of the other driving means, so that
the sound can be individualized. It becomes possible to output to stereo playback. Further, an
elastic supporting portion is provided on the opposite side to the rigid body supporting portion
across the driving means, and the diaphragm is elastically supported on the base via the elastic
supporting portion. it can. In addition, you may make it support in a free state, without providing
the said elastic support part. In addition, the thickness dimension of a part of the diaphragm
positioned outside the rigid body support may be thin, or the thickness dimension of the
diaphragm positioned outside the rigid body support may be It may be formed thinner than the
thickness dimension of the diaphragm located inside the said rigid body support part. As a result,
the diaphragm in the area driven by the driving means is easily vibrated, and the output of the
sound pressure can be increased. Further, the base is a display panel, and an image display area
of the display panel is provided in a predetermined area on the inner side of the rigid support or
on the driving means of each other. it can. As described above, when provided on the front
surface of the display panel, it is not necessary to provide a space for housing a speaker at
another position of the housing, and the device can be thinned and miniaturized. Further, since
the sound is emitted from the front of the display screen, it is easier to hear the sound than those
provided on the side of the housing. The present invention is not limited to the display panel, and
may be an operation panel. FIG. 1 is a perspective view showing the appearance of a flat speaker
according to a first embodiment, FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1,
and FIG. 3 is a drive means It is sectional drawing which shows. The flat speaker 1 according to
the present embodiment is installed on the surface of a display panel (base) 3 as shown in FIG.
The display panel is mounted on, for example, a portable information terminal such as a PDA
(Personal Digital Assistant), or a home appliance such as a microwave oven or a refrigerator.
Alternatively, instead of being provided on the front of the display panel, it may be provided on
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the front of the operation panel provided with a pressing operation button or the like. As shown
in FIG. 1, the flat speaker 1 of the present embodiment has a diaphragm 2 formed in a
rectangular shape and in a sheet shape. The diaphragm 2 is made of, for example, a highly
transparent material such as acrylic resin, polycarbonate, and glass.
The display panel 3 is formed to be thin such as liquid crystal or organic EL
(electroluminescence). As shown in FIG. 2, elastic support portions 4a and 4b are provided on the
surface (surface on the Z1 side) of the display panel 3, and the elastic support portions 4a and 4b
are the X1 side and the X2 side of the diaphragm 2. It is fixed at each end of the side. Further, as
shown in FIG. 1, the elastic support portions 4a and 4b are formed so as to extend from the end
on the Y1 side to the end on the Y2 side of the diaphragm 2, respectively. The elastic support
portions 4a and 4b can be selected from synthetic rubber, silicone rubber, foam of synthetic
resin, and the like. Therefore, the diaphragm 2 is elastically supported on the display panel 3 by
the elastic support portions 4a and 4b. As shown in FIGS. 1 and 2, on the back surface (Z2 side)
of the diaphragm 2, driving means 10a and 10b are provided in the vicinity of the inner side of
the elastic support portions 4a and 4b. As shown in FIG. 3, a drive coil 11 is provided on the side
of the diaphragm 2 in the drive means 10a (the same applies to the drive means 10b). The drive
coil 11 is formed by winding a wire made of a conductor such as copper in a square ring along
the vibration surface of the diaphragm 2 and fixing it to the diaphragm 2 with an adhesive.
Alternatively, a drive coil may be formed by fixing a bobbin made of a synthetic resin to the
diaphragm 2 and winding the wire around the bobbin. On the surface of the display panel 3 on
the Z 1 side, a yoke 12 is fixed at a position facing the drive coil 11. As shown in FIG. 3, the yoke
12 is formed on the bottom of the bottom 12a extending along the Y direction with a
predetermined width along the surface of the display panel 3, and perpendicular to both edges of
the bottom 12a in the Z direction. And the side portion 12b extending along the Y direction, and
the cutting surface in the ZX plane is formed to be concave. Further, on the bottom 12a of the
yoke 12, a magnet 13 formed of a permanent magnet is fixed. The magnet 13 is also formed to
extend in the Y direction in the same manner as the yoke 12. For example, as shown in FIG. 3, the
Z1 side is magnetized to the N pole, and the Z2 side is magnetized to the S pole. A gap G is
formed between the side portion 12 b of the yoke 12 and the magnet 13, and the tip of the drive
coil 11 is inserted in the gap G. In the drive means 10a (also 10b) formed in this manner, a
magnetic circuit passing through the N pole of the magnet 13, the drive coil 11, the yoke 12 and
the S pole of the magnet 13 is formed.
For example, in the case shown in FIG. 3, when current is applied to the current path 11a on the
right side of the drawing of the drive coil 11 so that the current flows from the front side to the
back side of the drawing, A driving force F1 directed to the Z2 side acts on the. The current path
11b on the left side of the paper surface of the drive coil 11 is energized so that current flows
from the back side to the front side of the paper surface, and similarly, the driving force F2 acts
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on the current path 11b in the Z2 direction. Accordingly, since the driving force in the same
direction is generated in both current paths 11a and 11b, the diaphragm 2 is deformed in the Z2
direction. Further, by reversing the current flowing through the drive coil 11, a driving force is
generated to deform the diaphragm 2 in the Z1 direction. The drive means 10a and 10b are not
limited to the above embodiment, and the shapes of the yoke 12 and the magnet 13 can be
changed as appropriate. Further, the magnet may be a moving magnet type fixed to the
diaphragm 2 side, or driving means using a piezoelectric element instead of the above magnetic
circuit may be used. In the present embodiment, as shown in FIGS. 1 to 3, rigid body support
portions 5a and 5b are provided inside the drive means 10a and 10b. The rigid support portions
5a and 5b are formed to extend to end portions on the Y1 side and the Y2 side. The rigid support
portions 5a and 5b are made of a highly rigid synthetic resin, metal or the like, and made of a
material that is not easily deformed. The rigid support portions 5a and 5b are fixed to the rear
surface of the diaphragm 2 on the Z1 side and the front surface of the display panel 3 on the Z2
side with an adhesive or the like. When rigid body support portions 5 a and 5 b are provided as
described above, when a predetermined signal is given to the drive coil 11 from a control portion
(not shown) and the diaphragm 2 is vibrated, the rigid body support portion 5 a and the rigid
body The diaphragm 2 in the region Q1 (see FIG. 1) sandwiched by the support portions 5b is
difficult to vibrate. That is, since the rigid support portions 5a and 5b are formed of high rigidity
members, they are difficult to deform, and the vibration of the diaphragm 2 generated by the
respective driving means 10a and 10b at the positions of the rigid support portions 5a and 5b. Is
interrupted or attenuated, so that the vibration is less likely to be transmitted to the central
portion of the diaphragm 2. Therefore, as shown in FIG. 2, only the diaphragm 2 of the portion
positioned on the outer side of the rigid support portions 5a and 5b is vibrated, and sound is
separately emitted on the X1 side and the X2 side of the diaphragm 2, Stereo playback becomes
possible.
In the present embodiment, the display panel 3 is mounted on the back side of the diaphragm 2
formed in a transparent color, but the image display area of the display panel 3 is in the range
indicated by the symbol Q 2 in FIG. . When the display area Q2 is thus set to the area between
the rigid body support 5a and the rigid body support 5b, the entire image displayed on the
display panel 3 can be viewed through the diaphragm 2. Therefore, the flat speaker 1 of the
present embodiment can be disposed so as to overlap the front surface of the display panel 3. As
described above, even if the display panel is provided behind the diaphragm, it can be placed on
the display panel in an overlapping manner, so that thinning and downsizing of the device can be
achieved. Moreover, the installation place of the flat speaker 1 is not limited largely. Further,
even if the diaphragm 2 is provided to cover the front surface of the display panel 3 as described
above, the portion of the diaphragm 2 facing the display area Q 2 of the display panel 3 vibrates.
Therefore, the image on the display panel 3 is not disturbed or the visibility is not impaired. FIG.
4 is a cross-sectional view showing a flat loudspeaker according to the second embodiment. In
the flat loudspeaker 1B shown in FIG. 4, the thickness dimension of a part of the outside of the
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rigid support portions 5a and 5b of the diaphragm 2 is formed thin. That is, concave notches 2a
and 2b are formed on the back surface of the diaphragm 2 positioned between the driving means
10a and 10b and the rigid support portions 5a and 5b. The notches 2a and 2b extend in the Y
direction along the rigid support portions 5a and 5b, respectively, and are formed thinner than
the other thickness dimension D of the diaphragm 2. The other configuration is the same as that
of the flat loudspeaker 1A, and therefore, the same reference numerals are given and the
description thereof is omitted. Therefore, in the flat loudspeaker 1B shown in FIG. 4, the
diaphragm 2 located outside the rigid body support portions 5a and 5b can be easily vibrated in
the Z direction with the position of the rigid body support portions 5a and 5b as a fulcrum. As a
result, the sound pressure output can be increased. FIG. 5 is a cross-sectional view showing a flat
loudspeaker according to a third embodiment. In this flat loudspeaker 1C, the thickness
dimension of the diaphragm 2 on the outside of the rigid support portions 5a and 5b is thinly
formed not entirely but partially as shown in FIG. The diaphragm 2 is set such that D2> D1 when
the thickness dimension inside the rigid body support portions 5a and 5b is D1 and the thickness
dimension outside is D2. Therefore, also in this case, the diaphragm 2 located outside the rigid
body support portions 5a and 5b can be vibrated to a large extent, so that sound can be output
more largely.
Further, as in the fourth embodiment shown in FIG. 6, the elastic support portions 4a and 4b are
removed, and the respective end portions on the X1 side and the X2 side of the diaphragm 2 are
set in free states. It is also good. Also in this case, the sound pressure can be increased because
the rigid body supporting portions 5a and 5b can be largely vibrated on the outer side of the
rigid body supporting portions 5a and 5b with the supporting points. In each of the abovedescribed embodiments, although the description has been given of the case where the pair of
driving means is provided on both sides of the sheet-like diaphragm, the present invention is not
limited to this. By installing the above, each driving means may be divided into three by the rigid
body support. As described above, according to the present invention, sound can be individually
output from different regions using a single sheet-like diaphragm. Further, the sound pressure
output can be increased by making it easy to vibrate the diaphragm corresponding to each drive
means. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the
appearance of a flat speaker according to a first embodiment, FIG. 2 is a cross-sectional view
taken along line 2-2 in FIG. 1, FIG. FIG. 4 is a sectional view showing a flat speaker according to a
second embodiment, FIG. 5 is a sectional view showing a flat speaker according to a third
embodiment, and FIG. 6 is a fourth embodiment 1A, 1B, 1C, 1D Flat panel 2 Diaphragm 2a, 2b
Notch 3 Display panel 4a, 4b Elastic support 5a, 5b Rigid body support 10a, 10b Driving means
11 drive coil 12 yoke 13 magnet
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