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JP2009164734

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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
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DESCRIPTION JP2009164734
The present invention provides a flat speaker with flat frequency characteristics over a wide
band. A flat speaker according to the present invention includes a flexible diaphragm 2 and a
plurality of actuator units 3 disposed on the back side of the diaphragm 2. The actuator unit 3
includes a diaphragm 2. And an actuator 5 for vibrating the diaphragm 2 in contact with the
diaphragm 2, and the actuator 5 is suspended by a suspension member 6 extending inward from
the frame 4. It is characterized by being suspended. [Selected figure] Figure 1
Flat speaker
[0001]
The present invention relates to a flat speaker, and more particularly to a flat speaker in which
an entire flexible diaphragm is vibrated by a plurality of actuators.
[0002]
Conventionally, there is known a flat speaker which generates sound by driving a plurality of
actuators disposed on the rear side of a diaphragm using a flexible member such as a screen as a
diaphragm (for example, see Patent Document) 1).
[0003]
The flat speaker has a plurality of actuators attached to the back side of the screen, and can
function as a multi-channel speaker.
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1
In addition, a plurality of actuators are attached to each channel to enable high output.
The actuator attached to the screen is a so-called voice coil type actuator, and includes a bobbin
around which the voice coil is wound and a yoke in which a permanent magnet is stored, and the
diaphragm is vibrated by the voice coil vibrating back and forth. Transmitting vibration to the
[0004]
JP 2000-236595 A
[0005]
In the flat loudspeaker described above, a plurality of actuators attached to the respective
channels are collectively fixed by a single attachment substrate from the rear of the yoke.
In addition, in the actuator to be fixed, when driven, the yoke receives a reaction force against the
vibration of the bobbin, and the yoke also vibrates. For this reason, when the speaker is driven,
vibrations generated in the yoke in one actuator are easily transmitted to the other adjacent
actuators through the mounting plate, and mutual interference is likely to occur between the
adjacent actuators. In addition, the difference in vibration mode also occurs due to the deviation
of the degree of perpendicularity between the actuator and the diaphragm (assembly error, error
between products), and from this point as well, mutual interference between the actuators is
likely to occur. Therefore, the sound output tends to be reduced in the low frequency band, and it
becomes difficult to obtain flat frequency characteristics over a wide band, and it is possible to
obtain a constant sound pressure level only in a narrow range in front of the flat speaker.
[0006]
Therefore, the present invention has been made in view of such circumstances, and provides a
flat speaker having flat frequency characteristics over a wide band and capable of maintaining a
constant sound pressure level in a wide range in the front direction. The purpose is to
[0007]
The flat speaker of the present invention for solving the above problems comprises a flexible
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diaphragm and a plurality of actuator units disposed on the back side of the diaphragm, and the
actuator unit is separated from the diaphragm And an actuator for contacting the diaphragm and
vibrating the diaphragm, wherein the actuator is suspended by a suspension member extending
inward from the frame. .
[0008]
Further, the flat speaker of the present invention includes a flexible diaphragm and a plurality of
actuators in contact with the back side of the diaphragm, wherein the actuator is in contact with
the diaphragm to vibrate the diaphragm. And suspended by a suspension member.
[0009]
Further, according to the flat speaker of the present invention, preferably, the frames in the
plurality of actuator units are polygons of the same shape.
[0010]
Moreover, according to the flat speaker of this invention, it is preferable that the said diaphragm
consists of a resin film, fiber cloth, or a non-fiber cloth.
[0011]
Furthermore, according to the flat speaker of the present invention, preferably, the plurality of
actuator units can appropriately adjust audio signals supplied to the individual actuators.
[0012]
According to the present invention, since the plurality of actuators constituting the flat speaker
are suspended by the frame via the suspension member, the vibration transmitted from the
actuator to the suspension member is attenuated and the other actuators are vibrated. Is difficult
to communicate.
Therefore, low-order resonance modes due to mutual interference between the actuators are
suppressed, acoustic output in the low frequency band is improved, and flat frequency
characteristics can be obtained over a wide band.
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[0013]
In addition, since each of the plurality of actuators constituting the flat speaker is suspended by
the frame via the suspension member, the deviation of the verticality between the actuator and
the diaphragm (assembly error, error between products) It is less likely to occur, and it is
possible to prevent the difference in vibration mode between the actuators and the occurrence of
mutual interference resulting therefrom.
[0014]
Furthermore, according to the present invention, since the plurality of actuators vibrate the
entire diaphragm such as the screen uniformly, the directivity is wide and the sound pressure
level is constant regardless of the position in front of the diaphragm. The listening range in a
good state is wider than in other types of speakers.
[0015]
The findings of the present invention can be readily understood in view of the following detailed
description with reference to the accompanying drawings, which are presented for the purpose
of illustration only.
Subsequently, embodiments of the present invention will be described with reference to the
accompanying drawings.
Where possible, the same parts will be denoted by the same reference symbols, without
redundant description.
[0016]
FIG. 1 is a schematic perspective view showing an embodiment of a flat loudspeaker according to
the present invention and a partially enlarged view of the same.
[0017]
As shown in FIG. 1, a flat speaker 1 according to an embodiment of the present invention has a
flexible diaphragm 2.
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The diaphragm 2 has a rectangular shape, and the material is appropriately selected according to
the desired acoustic characteristics.
For example, a resin film, fiber cloth, non-woven cloth, etc. can be used suitably.
In addition, if such a flexible member is selected, a screen for displaying an image, a panel of a
thin display device, or the like can be used as a diaphragm.
Further, since the present invention is characterized in that the entire diaphragm 2 is uniformly
vibrated by the plurality of actuators 5, the diaphragm 2 such as a screen vibrates the entire
diaphragm 2 in synchronization and uniformly. Hardness is desirable.
[0018]
Four actuator units 3 are arranged in two rows and two columns in the surface direction of the
diaphragm 2 at a substantially central portion on the back side of the diaphragm 2.
Each actuator unit 3 has a rectangular frame 4, and an actuator 5 for transmitting vibration to
the diaphragm 2 is suspended by a wire (suspension member) 6 at a substantially central portion
of the frame 4. The actuator 5 is in contact with the back of the diaphragm 2 via the excitation
plate 12.
Further, the diaphragm 2 is in contact with the actuator 5 only via the excitation plate 12 but not
in contact with the frame 4, and the predetermined distance L (see the partially enlarged view in
FIG. 1, L in FIG. ), And the method of supporting the frame 4 itself will be described later.
[0019]
Here, the actuator unit 3 will be described in detail with reference to FIGS. 2 and 3. FIG. 2 is a
front view showing only the actuator unit of FIG. 1 (the diaphragm 2 and the excitation plate 12
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are not shown) enlarged from the diaphragm side. 3 is a cross-sectional view taken along the line
III-III in FIG. 2, and FIG. 2 shows the configuration (positional relationship) in the case of being
attached to the diaphragm 2 and the excitation plate 12 not shown. .
[0020]
As shown in FIGS. 2 and 3, the actuator 5 suspended from the frame 4 is a known voice coil type
actuator. That is, the actuator 5 is provided with the yoke 7 which has the recessed part 7a
opened circularly, and the cylindrical bobbin 8. As shown in FIG. A disk-like permanent magnet
(not shown) having an outer diameter smaller than the inner diameter of the recess 7a is
accommodated in the recess 7a of the yoke 7, and a magnetic gap is formed by the gap between
the yoke 7 and the permanent magnet. There is.
[0021]
A voice coil (not shown) is wound around the outer peripheral surface of the bobbin 8, and a tip
end of the bobbin 8 is formed with a flange portion 8 a for transmitting vibration to the outside.
The flange portion 8a protrudes on the diaphragm side (left side in FIG. 3) with respect to the
end 4a of the frame 4 in order to reliably transmit the vibration to the diaphragm. Also, the
bobbin 8 is disposed to extend into the magnetic gap. Further, a bellows-like dustproof cover 9 is
mounted between the yoke 7 and the bobbin 8.
[0022]
The wire 6 is attached at one end to the upper side wall 4 b of the frame 4 and at the other end
to the yoke 7 of the actuator 5. The actuator 5 is supported only by the wire 6 and is disposed
substantially at the center of the frame 4 by its own weight. Therefore, the wire 6 can be freely
moved in the vertical direction with respect to the diaphragm 2, that is, in the expansion and
contraction (axial) direction of the actuator 5 by bending the wire 6 with the attachment position
of the wire 6 on the frame 4 side It is in the state. Furthermore, by suspending the actuator 5
with the wire 6, wrinkles and distortions are caused by the weight of the actuator 5 on the
diaphragm 2 such as a screen and the acoustic effect is reduced, and an image displayed on the
surface of the diaphragm 2 etc. Is prevented from being distorted. In particular, the wire 5
prevents the actuator 5 and the excitation plate 12 from hanging on the flexible diaphragm 2,
and the directions of expansion and contraction (axial) of the plurality of actuators 5 with respect
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to the diaphragm 2 are By being fixed in the vertical direction with respect to the diaphragm 2
and vibrating only in the vertical direction, the vibration directions among the plurality of
actuators 5 can be made to coincide, and the whole diaphragm 2 is uniformly made by the
plurality of actuators 5. It is possible to vibrate to obtain good acoustic characteristics.
[0023]
In addition, as a suspension member, not only a wire but a cord, a wire, etc. can also be used. As
for the actuator 5, not only the suspension of the actuator 5 by the wire 6 but also the diameter
of the actuator 5 is 30 mm to 60 mm in order to prevent the diaphragm 2 from being wrinkled
or distorted by the own weight of the actuator 5. As a matter of course, it is possible to prevent
the increase in size and weight and to minimize the influence on the diaphragm 2.
[0024]
Therefore, in order to transmit the vibration to the diaphragm efficiently, the direction of the axis
of the actuator 5 is adjusted such that the expansion (axial) direction (left and right direction in
FIG. 3) is perpendicular to the diaphragm. . This adjustment can be made by appropriately
selecting the attachment position of the wire 6 and the weight of the balance weight 11 provided
at the rear end of the yoke 7. By this adjustment, deviation of the verticality between the actuator
5 and the diaphragm 2 (assembly error, error between products) is less likely to occur, and the
difference in vibration mode between the actuators and the occurrence of mutual interference
resulting therefrom are prevented.
[0025]
Further, a hexagonal excitation plate 12 is provided on the back surface of the diaphragm 2 at a
position corresponding to the mounting position of the actuator 5, and the flange portion of the
actuator 5 is in contact with the excitation plate 12. The excitation plate 12 preferably has a
rigidity higher than that of the diaphragm 2. Thereby, even if it is the flexible diaphragm 2, the
vibration from the actuator 5 can be reliably transmitted to the diaphragm 2, and the acoustic
characteristic can be further improved. The shape of the excitation plate 12 is not particularly
limited, and may be rectangular or circular.
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[0026]
In the present embodiment, the actuator 5 is suspended by one wire, but may be suspended by a
plurality of wires. FIG. 4 is a schematic perspective view showing a modified example of the
actuator unit (the diaphragm 2 and the excitation plate 12 are not shown). As shown in FIG. 4,
the actuator unit 3 is suspended by two wires 6. That is, the actuator 5 is suspended above the
yoke 7 at two places in the axial direction of the actuator 5. As described above, by supporting
the actuator 5 at two points in the axial direction, the direction of the axis is further stabilized,
and it is reliably moved only in the expansion / contraction (axial) direction of the actuator 5, ie,
the direction perpendicular to the diaphragm 2. This enables the vibration directions of the
plurality of actuators 5 to coincide with one another, and it is further possible to uniformly
vibrate the entire diaphragm 2 to obtain good acoustic characteristics. Also, in order to vibrate
the entire diaphragm 2 such as a screen uniformly, the directivity is wide and the sound pressure
level is constant no matter where in the front of the diaphragm 2 the user listens. The listening
range in good condition is wider than that in
[0027]
Returning to FIG. 1, in the four actuator units 3, the frame bodies 4 of the same shape (rectangle)
are mutually connected in the vertical and horizontal directions by bolts, nuts, adhesives, etc.
Form. The shape of the frame 4 is not limited to a rectangle, and may be a hexagon or an
octagon. As described above, by using a polygonal frame having the same shape, connection of
the frames is facilitated, and an array structure can be easily formed.
[0028]
Here, as described above, the frame 4 of the actuator unit 3 is not in contact with the diaphragm
2 but is separated as indicated by L in FIGS. 1 and 3 and the supporting method is shown in FIG.
Shown in. 5A and 5B are a schematic perspective view and a partial enlarged view of the flat
speaker of FIG. 1 showing a method of supporting the actuator unit, wherein the outer peripheral
portion on the back side of the diaphragm 2 abuts on the diaphragm 2 and vibrates. A ring 13 is
arranged to surround the plate 2. Further, the elastic holding body 14 is disposed so as to cross
or longitudinally cut the inside of the housing 13 from the position corresponding to the end of
the outermost periphery of the plurality of frames 4 in the connected state inside the housing 13.
The frame 4 is supported by the outer peripheral portion of the frame 4 of the plurality of (four
in FIG. 5) connected actuator units 3 being in contact with the elastic holding body 14. Further,
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as apparent from M in the partial enlarged view in FIG. 5, the diaphragm 2 and the elastic
holding body 14 are separated by a predetermined distance, and the frame 4 of the actuator unit
3 is the elastic holding body 14 and the housing 13. , And is fixed to the diaphragm 2. By
adopting this configuration, the actuator 5 is in contact with the diaphragm 2 only via the
excitation board 12, and the plurality of actuators 5 constituting the flat speaker are other
members due to the presence of the wire 6 in the frame 4. Vibration is less likely to be
transmitted to the actuator 5, low-order resonance modes due to mutual interference between
the actuators 5 are suppressed, acoustic output in the low frequency band is improved, and flat
frequency characteristics are obtained over the entire diaphragm 2 such as a screen. can get.
[0029]
Moreover, in this embodiment, although arranged in 2 rows and 2 columns, the number of the
actuator units 3 may be increased according to the size of the diaphragm and desired acoustic
characteristics. 6 and 7 are schematic perspective views of modifications of the flat loudspeaker
of FIG. In the modification shown in FIG. 6, nine actuator units 3 (three rows and three columns)
are provided, and FIG. 7 shows a configuration including sixteen actuator units 3 (four rows and
four columns). . Even if the number of arrangement of the actuator units 3 is increased, since
mutual interference among the actuators 5 is small, it is possible to obtain an acoustic output
according to the increase in the number of arrangement while maintaining a wide band and flat
frequency characteristics. .
[0030]
In the flat speaker 1 configured as described above, when an audio signal is supplied to the voice
coils of the plurality of actuators 5 via the signal line (not shown), the bobbin 8 vibrates in the
axial direction. This vibration is transmitted to the excitation plate 12 through the flange portion
8a of the bobbin 8 and further transmitted to the diaphragm 2, whereby the entire diaphragm 2
is uniformly vibrated and is emitted forward. Here, if the audio signals supplied to the individual
actuators 5 are appropriately adjusted, it can also be driven as a multi-channel flat speaker. For
example, with regard to the three rows and three columns in total of nine actuator units 3 shown
in FIG. 6, it is also possible to provide a 3CH speaker by appropriately adjusting the audio signal
for each of the right column, center column, left column and the column. Further, if the acoustic
correction such as the signal of the reflected sound (noise) elimination is added according to the
acoustic environment such as the installation place, the selection range of the installation place
can be expanded.
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[0031]
As described above, in the flat speaker 1, since the actuator 5 constituting the flat speaker 1 is
suspended from the frame 4 via the wire 6, the vibration transmitted from the actuator 5 to the
wire 6 is attenuated. Vibration is less likely to be transmitted to the other actuators 5. Therefore,
low-order resonance modes due to mutual interference are suppressed between the actuators 5,
sound output in the low frequency band is improved, and flat frequency characteristics can be
obtained over a wide band.
[0032]
In addition, since the plurality of actuators 5 vibrate the entire diaphragm 2 such as a screen
uniformly, the directivity is wide and the sound pressure level is constant regardless of the
position in front of the diaphragm 2. The listening range in a good state is wider than that of
other type speakers.
[0033]
An experiment was conducted to confirm that the acoustic characteristics are improved for the
flat speaker according to the present invention.
Hereinafter, the present invention will be described in more detail by way of examples, but the
present invention is not limited to these examples.
[0034]
Example 1 A flat loudspeaker (example) in which four speaker units were disposed on the back
side of the diaphragm as shown in FIG. 1 was prepared, and the acoustic characteristics were
examined. Also, for comparison, a conventional flat speaker, ie, a flat speaker in which actuators
are arranged in 2 rows and 2 rows on the back side of the diaphragm and these actuators are
collectively fixed by a single mounting plate from behind The acoustic characteristics were
examined by preparing (conventional example).
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[0035]
FIG. 8 shows experimental data indicating acoustic characteristics of the flat speakers of the
example and the conventional example. In FIG. 8, the horizontal axis is frequency (Hz), the
vertical axis is amplitude of sound output (dBSPL), and a curve indicated by a solid line is an
acoustic characteristic of the flat speaker of this embodiment. Further, a curve indicated by a
broken line is an acoustic characteristic of the flat speaker of the conventional example.
[0036]
In this experiment, a signal of 1 W was input to a speaker, and the sound pressure [dB] was
measured 1 m ahead of the center of the speaker, which is in accordance with the SPL (Sound
Pressure Level) method.
[0037]
When these acoustic characteristics are compared, it can be seen that the acoustic characteristics
of the flat speaker according to the present embodiment extend to the bass range compared to
the conventional flat speaker, and the frequency characteristics are wider and flat.
[0038]
(Example 2) The acoustic characteristic of the flat speaker when the arrangement number of the
actuator unit arranged on the back side of the diaphragm prepares 4, 9, 25 flat speakers and
changes the arrangement number of the actuator unit I examined.
In addition, the flat speaker in which one actuator unit was arrange | positioned as a reference
was also prepared, and the acoustic characteristic was similarly investigated.
The experimental method is the same as in Example 1.
[0039]
FIG. 9 is experimental data showing acoustic characteristics when the number of arrangement of
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actuator units is changed. In FIG. 9, the horizontal axis is the frequency (Hz), and the vertical axis
is the amplitude of the sound output (dBSPL). Here, a curve shown by a solid line is an acoustic
characteristic of the flat speaker when driven by one actuator unit. A curved line indicated by a
broken line is an acoustic characteristic of the flat speaker when driven by four (two rows and
two columns) actuator units. A curved line indicated by an alternate long and short dash line is
an acoustic characteristic of the flat speaker when driven by nine (three rows and three columns)
actuator units. Curves shown by dotted lines are acoustic characteristics of the flat speaker when
driven by 25 (5 rows and 5 columns) actuator units.
[0040]
Comparing these acoustic characteristics, the acoustic output is improved while maintaining flat
frequency characteristics in a wide band according to the number of arrangement of the actuator
units. For example, the acoustic output at 1000 Hz represents 70 dB in the case of one actuator
unit, 76 dB in the case of four, 80 dB in the case of nine, and 84 dB in the case of 25. Indicated.
This is approximately the theoretical efficiency improvement, and is considered to be because the
mutual interference between the actuators is reduced.
[0041]
On the other hand, with the fixed structure of the actuator in the conventional flat loudspeaker,
even if the number of arranged actuators is changed to 1, 4, 9, 25 as in the above, the efficiency
improvement according to the theoretical value can only be obtained up to four. The This is
presumed to be due to mutual interference occurring between adjacent actuators.
[0042]
The experiments according to the first and second embodiments are based on the SPL method in
which a signal of 1 W is input to a speaker and the sound pressure [dB] is measured 1 m ahead
of the center of the speaker, but the present invention According to the above, since the plurality
of actuators 5 vibrate the whole diaphragm 2 such as a screen uniformly, the directivity is good
even when listening not only at the center of the front of the diaphragm 2 but also at other
positions on the front. The sound pressure level is wide, and the listening range in a good state is
wide.
[0043]
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It is the schematic perspective view which shows one Embodiment of the flat speaker which
concerns on this invention, and the elements on larger scale of the figure.
It is a front view which expands and shows the actuator unit of FIG. 1 from the balance weight
side. It is the III-III sectional view taken on the line of FIG. It is a perspective view which shows
the modification of an actuator unit. It is the schematic perspective view which shows the
support method of the frame of an actuator unit about the planar speaker of FIG. 1, and the
elements on larger scale of the figure. It is a schematic perspective view of the modification of
the flat speaker of FIG. It is a schematic perspective view of the other modification of the flat
speaker of FIG. It is experimental data which shows the acoustic characteristic of the planar
speaker of an Example and a prior art example. It is experimental data which shows the acoustic
characteristic at the time of changing the arrangement | positioning number of an actuator unit.
Explanation of sign
[0044]
DESCRIPTION OF SYMBOLS 1 flat speaker 2 diaphragm 3 actuator unit 4 frame 4 a end 4 b side
wall 5 actuator 6 wire 7 yoke 8 bobbin 8 a flange portion 9 dustproof cover 11 balance weight
12 excitation plate 13 conductor 14 elastic holder
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