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JP2010093769

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DESCRIPTION JP2010093769
A speaker system integrated with a display panel is provided so that the thickness of the display
panel portion can be sufficiently reduced. A display panel (40) is inserted inside a bezel (10), and
the bezel (10) is supported on the display panel (40). The laminated piezoelectric actuator 70L is
attached to the back side of the left side plate portion 13 of the bezel 10, and the laminated
piezoelectric actuator 70R is attached to the back side of the right side plate portion 14. The
displacement direction (vibration direction) of the laminated piezoelectric actuators 70L and 70R
is set to be the plate surface direction of the bezel 10. The vibrations of the laminated
piezoelectric actuators 70L and 70R are transmitted to the bezel 10 as longitudinal vibrations
along the plate surface of the bezel 10, and sound waves are emitted in the front direction
perpendicular to the plate surface of the bezel 10. [Selected figure] Figure 2
Speaker system and speaker driving method
[0001]
The present invention relates to a loudspeaker system integrated with a display panel, such as a
video display and audio output device of a flat screen television receiver, and a method of driving
the loudspeaker system.
[0002]
Television receivers are becoming thinner and thinner.
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1
In October 2007, the applicant has put on the market an organic EL display in which the display
panel portion is thinned to a thickness of 3 mm.
[0003]
On the other hand, as a speaker device, not a normal speaker unit having a voice coil and a cone,
but one that generates vibration by applying vibration to an acoustic diaphragm by an actuator
such as a super magnetostrictive actuator is considered.
[0004]
Specifically, Japanese Patent Laid-Open Nos. 4-313999 and 2005-177688 disclose a speaker
apparatus as shown in FIGS. 18A and 18B. There is.
[0005]
In the speaker device of FIG. 18, the drive rod 2 a of the magnetostrictive actuator 2 is abutted
against the central portion of the flat acoustic diaphragm 1 so that the displacement direction is
perpendicular to the plate surface of the acoustic diaphragm 1. The acoustic diaphragm 1 is
vibrated in the direction perpendicular to the plate surface.
[0006]
However, in the speaker device of FIG. 18, the amplitude of the vibration is maximum at the
central portion of the acoustic diaphragm 1 as shown by the arrow 3a, and the amplitude of the
vibration is smaller as shown by the arrow 3b at a point away from the excitation point. As a
result, uniform vibration can not be obtained in each part of the acoustic diaphragm 1.
[0007]
On the other hand, the speaker apparatus as shown to FIG. 19 (A) (B) is shown by patent
document 3 (Unexamined-Japanese-Patent No. 2007-166027).
[0008]
In the speaker device shown in FIG. 19, the cylindrical acoustic diaphragm 4 is vertically
supported, and a plurality of actuators 5 such as super magnetostrictive actuators are disposed
on the lower end side of the acoustic diaphragm 4, and the drive rods 5a are acoustic
diaphragms. The acoustic diaphragm 4 is made to vibrate in a direction perpendicular to the
lower end face by bringing the acoustic diaphragm 4 into contact with the lower end face 4.
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2
[0009]
In the speaker apparatus of FIG. 19, the lower end face of the acoustic diaphragm 4 is excited by
the longitudinal wave, but the vibration elastic wave propagates in the direction of the plate
surface of the acoustic diaphragm 4 to become a wave in which the longitudinal wave and the
transverse wave are mixed. Thus, the acoustic wave is emitted by the transverse wave in the
direction perpendicular to the plate surface of the acoustic diaphragm 4.
[0010]
Therefore, in the speaker device of FIG. 19, as indicated by the arrow 6 a, sound waves are
emitted at a uniform level at any position in the axial direction of the acoustic diaphragm 4, and a
sound image is localized uniformly throughout the acoustic diaphragm 4.
[0011]
The prior art documents mentioned above are as follows.
JP-A-4-313999 JP-A-2005-177688 JP-A-2007-166027
[0012]
Since the application has not been published yet, it is not shown as a prior art document, but
Japanese Patent Application No. 2007-304010 proposes a speaker device as shown in FIGS. 20
(A) and (B).
[0013]
In the speaker apparatus of FIG. 20, the square hole 7a is formed in the flat acoustic diaphragm
7, the actuator 8 having the drive rod 8a is mounted in the square hole 7a, and the vibration in
the plate surface direction is applied to the acoustic diaphragm 7. .
[0014]
Also in the loudspeaker apparatus of FIG. 20, as in the loudspeaker apparatus of FIG. 19, the
sound wave is emitted at a uniform level from any part of the acoustic diaphragm 7 as indicated
by the arrow 9a.
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[0015]
Furthermore, in the speaker device of FIG. 20, the thickness of the speaker can be made as small
as the thickness of the acoustic diaphragm 7.
[0016]
As described above, when the display panel portion is thinned to about several mm or less, a
normal speaker unit is incorporated in the display panel portion to maintain the thickness of the
display panel portion to about several mm or less. Have difficulty.
[0017]
Also in the case where a speaker device for vibrating the acoustic diaphragm 1 in a direction
perpendicular to the plate surface as shown in FIG. 18 is incorporated in the display panel
portion, the longitudinal direction of the giant magnetostrictive actuator 2 is the direction
perpendicular to the panel surface Therefore, it is difficult to maintain the thickness of the
display panel portion to about several millimeters or less.
[0018]
Therefore, the present invention is a speaker system integrated with a display panel so that the
thickness of the display panel can be sufficiently reduced.
[0019]
A speaker system according to the present invention includes: a display panel having a display
screen; a plate portion located outside the periphery of the display screen and functioning as an
acoustic diaphragm; a structure supported by the display panel; An actuator attached to the
structure such that a displacement direction of the actuator is in a direction of a plate surface of
the plate portion.
[0020]
In the speaker system according to the present invention described above, for example, actuators
are provided on the left and right sides of the display screen of the frame plate-like structure, and
the length direction thereof corresponds to the plate surface direction of the structure. Attached
to the
[0021]
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4
Therefore, even if the length of the actuator as the excitation unit is large, the thickness of the
display panel can be sufficiently reduced.
[0022]
As described above, according to the present invention, the thickness of the display panel portion
of the speaker system integrated with the display panel can be sufficiently reduced.
[0023]
[1.
First Embodiment: FIGS. 1 to 9] In the first embodiment of the speaker system according to the
present invention, the laminated piezoelectric actuators are attached to the left and right plate
portions of the display screen of the bezel as a structure. Indicates
[0024]
(1−1.
Example of First Embodiment: FIGS. 1 to 6) <1-1-1.
Overall Configuration: FIGS. 1 to 3> FIGS. 1, 2 and 3 show an example of a speaker system
according to the first embodiment.
[0025]
1 is a back view of the bezel, FIG. 2 is a back view of the bezel supported by the display panel,
and FIG. 3 is a perspective view of the actuator in FIGS. 1 and 2 It is a figure which shows the
cross section of a part.
[0026]
In the following, the upper side is the upper side of the display screen, the lower side is the lower
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5
side of the display screen, the left side is the left side of the display screen viewed from the front
side, and the right side is the display screen viewed from the front side On the right.
[0027]
As shown in FIGS. 1 and 2, the bezel 10 has a frame plate shape (frame shape) having an upper
side plate portion 11, a lower side plate portion 12, a left side plate portion 13 and a right side
plate portion 14.
[0028]
Since the bezel 10 functions as an acoustic diaphragm, it is desirable that the bezel 10 be made
of a material having good acoustic characteristics.
For example, if it is a metal, magnesium is suitable.
[0029]
A strip-shaped rubber piece 15 is attached to the back side of the upper side plate portion 11,
and a ring-shaped rubber piece 16 is attached to the back side of the lower side plate portion 12,
the left side plate portion 13 and the right side plate portion 14.
[0030]
Screw holes 17 for attaching the bezel 10 to the display panel 40 are formed on the back side of
the left side plate 13 and the right side plate 14.
[0031]
Screw holes 18 and 19 for attaching a rear cover 60 shown in FIG. 3 are formed on the back side
of each corner of the bezel 10 and on the back side of the upper side plate portion 11 and the
lower side plate portion 12.
[0032]
Furthermore, the laminated piezoelectric actuators 70L and 70R are attached to the back side of
the left side plate portion 13 and the right side plate portion 14 of the bezel 10.
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[0033]
In this example, the left side plate portion 13 is provided with the receiving portions 21 and 22
projecting to the back side, and the receiving portion 21 and the receiving portion 22 are
arranged such that the displacement direction (vibration direction) of the laminated piezoelectric
actuator 70L is the screen vertical direction. Attach between.
[0034]
Similarly, the right side plate 14 is provided with the receiving parts 21 and 22 projecting to the
back side, and the laminated piezoelectric actuator 70R is arranged so that the displacement
direction (vibration direction) thereof is the screen vertical direction. Attach between
[0035]
The receiving portions 21 and 22 are formed integrally with the bezel 10, or are formed
separately from the bezel 10 and attached to the bezel 10 by screws or an adhesive.
The laminated piezoelectric actuators 70L and 70R are attached to the bezel 10, for example, via
an adhesive between the receiving portions 21 and 22, respectively.
[0036]
The vibrations of the laminated piezoelectric actuators 70L and 70R are transmitted to the bezel
10 through the receiving portions 21 and 22, respectively, as longitudinal vibrations along the
plate surface.
As a result, sound waves are emitted in the front direction perpendicular to the plate surface of
the bezel 10.
[0037]
Therefore, it is desirable that the receiving parts 21 and 22 be made of a hard material in order
to propagate the vibration efficiently.
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[0038]
Further, a tape-like buffer member 31 is attached to the back side of the upper side plate portion
11, the lower side plate portion 12, the left side plate portion 13 and the right side plate portion
14 with a double-sided tape or the like.
As the buffer member 31, non-woven fabric such as Hemelon (trade name) can be used.
[0039]
The display panel 40 is a flat display panel such as an organic EL display panel, and an image is
displayed on the display screen.
[0040]
A chassis 50 is attached to the back of the display panel 40.
Although not shown, a circuit board or the like is attached to the chassis 50.
[0041]
As shown in FIG. 2, the display panel 40 to which the chassis 50 is attached is inserted on the
back side of the bezel 10 so as to be sandwiched by the rubber pieces 15 and 16, and the screws
51 are inserted from the outside of the chassis 50. The bezel 10 is supported on the display
panel 40 by tightening the screw holes 17 shown in FIG.
[0042]
At this time, the rubber pieces 15 and 16 are slightly indented and elastically abut on the
peripheral end face of the display panel 40, thereby absorbing the relative positional variation in
the surface direction of the display screen of the bezel 10 and the display panel 40. As a result,
damage to the display panel 40 due to impact is prevented.
[0043]
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Further, at this time, the buffer member 31 is interposed between the bezel 10 and the
peripheral portion of the display panel 40 to improve acoustic characteristics as described later.
[0044]
After the bezel 10 is supported by the display panel 40, the rear cover 60 is placed on the back
side of the bezel 10 as shown in FIG. 3 and screws are tightened from outside the rear cover 60
into the screw holes 18 and 19 shown in FIG. Then, attach the rear cover 60 to the bezel 10.
[0045]
In this case, when the receiving portions 21 and 22 constituting the actuator attachment portion
are close to the rear cover 60, the buffer member 32 is attached also to the receiving portions 21
and 22, and the space between the receiving portions 21 and 22 and the rear cover 60 And the
buffer member 32 is interposed.
[0046]
<1−1−2.
Laminated Piezoelectric Actuator: FIG. 4> FIG. 4 shows an example of a laminated piezoelectric
actuator used as the laminated piezoelectric actuator 70L or 70R.
FIG. 4A is a schematic perspective view, and FIG. 4B is a schematic cross-sectional view.
[0047]
In the laminated piezoelectric actuator element of this example, external electrodes 72 and 73
are formed on the facing side surfaces of the piezoelectric ceramic thin plate laminate 71.
[0048]
The piezoelectric ceramic thin plate laminate 71 is formed by laminating a large number of
piezoelectric ceramic thin plates and alternately sandwiching internal electrodes 74 and 75
therebetween.
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The internal electrode 74 is connected to the external electrode 72, and the internal electrode 75
is connected to the external electrode 73.
[0049]
When the signal voltage Vs obtained from the signal source 76 is applied between the external
electrodes 72 and 73, the individual piezoelectric ceramic thin plates are displaced in the
thickness direction by polarization, and the piezoelectric ceramic thin plate laminate 71
corresponds to the total of the respective displacements, It displaces in the stacking direction and
vibrates.
[0050]
The laminated piezoelectric actuator can have a width W of about 3.5 mm and a depth D of about
2 mm in the direction in which the external electrodes 72 and 73 face each other.
[0051]
Therefore, the laminated piezoelectric actuator element is attached to the bezel 10 so that the
direction of the width W is parallel to the display screen and the direction of the depth D is
perpendicular to the display screen.
[0052]
By this, the speaker system of the example of FIGS. 1-3 can be about several mm or less in
thickness.
[0053]
As described above, unlike the magnetostrictive actuator, since the laminated piezoelectric
actuator does not require a magnetic field bias, the actuator can be configured more simply and
can be miniaturized.
[0054]
Moreover, the laminated piezoelectric actuator has a large generated stress and a high response
speed, like the magnetostrictive actuator.
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10
[0055]
<1−1−3.
Action: FIG. 5 and FIG. 6> In the speaker system of the example of FIGS. 1 to 3, as described
above, the vibration of the laminated piezoelectric actuators 70L and 70R is transmitted to the
bezel 10 as longitudinal vibration, and is perpendicular to the plate surface of the bezel 10 Sound
waves are emitted in the front direction.
[0056]
Furthermore, by interposing the buffer member 31 between the bezel 10 and the peripheral
portion of the display panel 40, variations in acoustic characteristics due to individual differences
of the bezel 10 are absorbed as described below, and the acoustic characteristics are improved.
[0057]
FIG. 5 shows differences in sound pressure level frequency characteristics due to individual
differences of the bezel 10 when the cushioning member 31 is not present and the bezel 10 is in
direct contact with the peripheral portion of the display panel 40.
[0058]
Sample A, sample B, sample C and sample D are slightly different in warping degree and the like
in four bezels manufactured from the same material (magnesium) by the same manufacturing
method and in the same size.
[0059]
In this case, it was found that the frequency characteristics of the sound pressure level fluctuated
depending on the individual differences of the bezel, and in the sample A, the sound pressure
level significantly decreased around 8 kHz.
[0060]
On the other hand, FIG. 6 shows the case where the buffer member 31 is interposed between the
bezel 10 and the peripheral portion of the display panel 40 as in the above example.
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11
[0061]
In this case, the transmission of the vibration of the bezel 10 to the display panel 40 is blocked,
so that the difference in sound pressure level frequency characteristics due to the individual
difference of the bezel 10 becomes extremely small, and the sound pressure level of a certain
sample becomes middle and high. There is no significant drop around certain frequencies in the
region.
[0062]
In addition, since the laminated piezoelectric actuator is capacitive, when the laminated
piezoelectric actuators 70L and 70R are attached to the bezel 10 as shown in the example of
FIGS. 1 to 3, as shown in FIGS. The sound pressure level increases as the
This can be dealt with as described later.
[0063]
<1−1−4.
Driving Method> In the speaker system of the example of FIGS. 1 to 3, the laminated piezoelectric
actuators 70L and 70R can be driven by the same audio signal.
[0064]
Also, the laminated piezoelectric actuator 70L is driven by the left channel signal of the stereo
audio signal, and the laminated piezoelectric actuator 70R is driven by the right channel signal of
the stereo audio signal, etc., and the laminated piezoelectric actuators 70L and 70R are driven by
another audio signal. You can also
[0065]
Furthermore, as described later, the laminated piezoelectric actuators 70L and 70R can also be
driven by mid-high frequency components in the audio signal.
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12
[0066]
In any case, the sound image is localized outside the left side and the right side of the display
screen in terms of hearing.
[0067]
(1−2.
Example of Adding Preload: FIG. 7) In the speaker system of the example of FIGS. 1 to 3, for
example, when the bezel 10 is formed of a metal such as magnesium, when the bezel 10 is
elongated due to the temperature increase, the laminated piezoelectric actuator 70L and 70R are
pulled.
[0068]
However, the piezoelectric element is mechanically weak against tension.
Therefore, it is desirable to apply a preload to the laminated piezoelectric actuators 70L and 70R.
The sound quality is also improved by applying a preload to the laminated piezoelectric actuators
70L and 70R.
[0069]
Therefore, it is desirable to apply a preload to the laminated piezoelectric actuators 70L and 70R
by using an eccentric cam ring, a disk cam, or the like for the actuator mounting portion.
[0070]
An example is shown in FIG.
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13
FIGS. 7A, 7B, and 7C are views of the left side plate portion and the right side plate portion of the
bezel 10 as viewed from the back side.
[0071]
In this example, one end portion of the laminated piezoelectric actuator element is inserted into
the receiving portion 24 so that the receiving portion 24 is shaped such that one end portion of
the laminated piezoelectric actuator element is inserted from above.
[0072]
When one end of the laminated piezoelectric actuator element is inserted into the receiving
section 24, as shown in FIG. 7A, the eccentric cam ring 23 is attached to the shaft section 23a of
the bezel 10 at the other end of the laminated piezoelectric actuator element.
[0073]
From this state, through the state of FIG. 7B, as shown in FIG. 7C, the eccentric cam ring 23 is
rotated so that the eccentric cam ring 23 presses the laminated piezoelectric actuator element in
the displacement direction (vibration direction). .
[0074]
After adjustment, the eccentric cam ring 23 may be fixed to the bezel 10 with an adhesive or the
like so that the eccentric cam ring 23 does not rotate to the adjusted rotational position due to
external vibration or impact.
[0075]
(1−3.
Other Examples of Actuator Attachment: FIGS. 8 and 9) The actuator attachment of the bezel 10
can also be configured as follows.
[0076]
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14
An example is shown in FIG.
FIG. 8A is a view of the left side plate portion and the right side plate portion of the bezel 10 as
viewed from the back side, and FIG. 8B is a cross-sectional view thereof.
[0077]
In this example, a groove 25 is formed on the back side of the left side plate portion and the right
side plate portion of the bezel 10, and the laminated piezoelectric actuator element is attached
with the adhesive 26 in the groove 25.
[0078]
In order to efficiently transmit the vibration of the laminated piezoelectric actuator element to
the bezel 10, the adhesive 26 is preferably made of a hard material.
[0079]
Another example is shown in FIG.
FIG. 9 (A) shows an actuator mounting plate to which the laminated piezoelectric actuator is
attached, and FIG. 9 (B) is a side view in which a bezel portion is sectioned.
[0080]
In this example, an actuator mounting plate 27 having a hole 28 for passing a screw is prepared
separately from the bezel 10, and the laminated piezoelectric actuator element is attached to the
actuator mounting plate 27 with an adhesive or double-sided tape.
[0081]
The actuator mounting plate 27 to which the laminated piezoelectric actuator element is attached
as described above is attached to the back side of the left side plate portion and the right side
plate portion of the bezel 10 with screws 29 respectively.
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[0082]
In this example, since the laminated piezoelectric actuator element is made into an adapter, the
laminated piezoelectric actuator element can be efficiently attached to the bezel 10, and the mass
productivity of the speaker system is improved.
[0083]
[2.
Second Embodiment: FIG. 10 and FIG. 11] In the first embodiment described above, as shown in
FIG. 10A, the bezel 10 of the displacement direction (vibration direction) indicated by the arrow
79 of the laminated piezoelectric actuator element. The angle α with respect to the extension
direction (screen left-right direction) of the end face 10a is a right angle.
[0084]
Therefore, the longitudinal wave propagated from the excitation point Pa of the bezel 10 to the
point Pr on the end face 10a is reflected at the point Pr in the displacement direction of the
laminated piezoelectric actuator element and reflected at the point Pr and the longitudinal wave
propagating to the point Pr It generates resonance with the longitudinal wave.
The same applies to the end face opposite to the end face 10a.
[0085]
Therefore, in the second embodiment, as shown in FIG. 10B, an angle with respect to the
extension direction (screen lateral direction) of the end face 10a of the bezel 10 in the
displacement direction (vibration direction) indicated by the arrow 79 of the laminated
piezoelectric actuator element. Is between 0 ° and 90 °, not at right angles.
[0086]
According to this, the longitudinal wave propagated from the excitation point of the bezel 10 to a
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point on the end face 10a is mainly reflected at a point on the end face 10a in a direction
different from the displacement direction of the laminated piezoelectric actuator element. The
resonance due to waves is reduced.
The same applies to the end face opposite to the end face 10a.
[0087]
FIG. 11 shows an example of a speaker system according to the second embodiment.
FIG. 11 is a front view of the speaker system, and the laminated piezoelectric actuator is
indicated by a broken line.
[0088]
In this example, the laminated piezoelectric actuator 70L is attached to the back side of the left
side plate portion of the bezel 10 with its displacement direction slightly inclined to the screen
vertical direction, and the laminated piezoelectric actuator 70R is mounted to the back side of the
right side plate portion of the bezel 10. Are mounted symmetrically with respect to the laminated
piezoelectric actuator 70L.
[0089]
[3.
Third Embodiment: FIGS. 12 and 13] As a third embodiment of the speaker system according to
the present invention, a case where four laminated piezoelectric actuators are attached to a bezel
is shown.
[0090]
(3−1.
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17
Example of Third Embodiment: FIG. 12 FIG. 12 shows an example of a speaker system according
to a third embodiment, and is a view of the speaker system as viewed from the front side, as in
FIG.
[0091]
In this example, the laminated piezoelectric actuator 70L is attached to the back of the central
portion of the left side plate of the bezel 10 in the vertical direction of the screen, and the
laminated piezoelectric actuator is mounted on the rear of the central portion of the right side of
the bezel 10 in the vertical direction Install the 70R.
[0092]
Furthermore, the laminated piezoelectric actuator element Cu is attached to the rear side of the
central portion of the upper side plate portion of the bezel 10 in the left and right direction of the
screen, and the laminated piezoelectric actuator is formed on the rear side of the central portion
of the lower side plate portion of the bezel 10 in the horizontal direction Attach Cd.
[0093]
In this example, the sound image can be moved and localized in conjunction with the movement
of an object or the like displayed on the display screen 41 by controlling the level and the phase
of the audio signal supplied to each laminated piezoelectric actuator.
[0094]
For example, the level of the signal supplied to the laminated piezoelectric actuator 70L is
equalized to the level of the signal supplied to the laminated piezoelectric actuator 70R, and the
level of the signal supplied to the laminated piezoelectric actuator Cu is supplied to the laminated
piezoelectric actuator Cd. Greater than the level of the signal being
Thus, the sound image can be localized at the upper position in the vertical direction of the
center of the display screen 41 in the horizontal direction.
[0095]
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18
(3−2.
Another Example of Third Embodiment: FIG. 13 FIG. 13 shows another example of the speaker
system according to the third embodiment, and is a view of the speaker system as viewed from
the front side as in FIG.
[0096]
In this example, the laminated piezoelectric actuator 70Lu is attached to the back side of the
upper left corner of the bezel 10 with its displacement direction inclined 45 ° with respect to
the screen horizontal direction and the screen vertical direction. The laminated piezoelectric
actuator 70Ld is mounted vertically symmetrically with respect to the laminated piezoelectric
actuator 70Lu.
[0097]
The laminated piezoelectric actuators 70Ru and 70Rd are attached to the back side of the upper
right corner and the lower right corner of the bezel 10 in left-right symmetry with respect to the
laminated piezoelectric actuators 70Lu and 70Ld, respectively.
[0098]
Also in this example, the sound image can be moved and localized in conjunction with the
movement of the object or the like displayed on the display screen 41 by controlling the level
and the phase of the audio signal supplied to each laminated piezoelectric actuator.
[0099]
For example, the levels of the signals supplied to the laminated piezoelectric actuators 70Lu and
70Ru are increased, and the levels of the signals supplied to the laminated piezoelectric actuators
70Ld and 70Rd are reduced.
Thus, the sound image can be localized at the upper position in the vertical direction of the
center of the display screen 41 in the horizontal direction.
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19
[0100]
Furthermore, in this example, since the angle of the displacement direction (vibration direction)
of each laminated piezoelectric actuator with respect to the extension direction of the end face of
the bezel 10 is 45 °, the resonance by the reflected wave is an example of the second
embodiment described above. Is reduced.
[0101]
[4.
Fourth Embodiment: FIG. 14 to FIG. 16] As a speaker system according to the present invention,
as shown in the fourth embodiment below, not only the actuator is attached to the display panel
as described above, but also the normal A speaker unit can be provided.
[0102]
(4−1.
Example of Fourth Embodiment: FIG. 14 and FIG. 15 FIG. 14 shows an example of a speaker
system according to a fourth embodiment.
In this example, the display panel unit 90 is attached to the pedestal box 110 by the support
100.
[0103]
The display panel unit 90 has the laminated piezoelectric actuators 70L and 70R attached to the
back side of the left side plate portion and the right side plate portion of the bezel 10 as in the
speaker system and the like in the example of FIGS.
[0104]
On the pedestal box 110, the usual speaker units 120L and 120R having voice coils and cones
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are attached at the left and right positions as viewed from the front side, with the front sides of
the speakers facing upward.
[0105]
In this example, an excitation type speaker constituted by the laminated piezoelectric actuators
70L and 70R and the bezel 10 functions as a tweeter, and normal speaker units 120L and 120R
function as a woofer.
[0106]
In this case, since the tweeter band has a frequency response specific to the configuration of the
excitation speaker, the frequency characteristic is corrected by a digital signal processor (DSP) as
needed.
[0107]
Specifically, the left channel signal SL and the right channel signal SR, which are converted to
analog signals after digital processing of the stereo audio signal for frequency correction and the
like, are obtained from the DSP 130.
[0108]
The signal SL of the left channel is amplified by the voice amplification circuit 141 and then
separated into the middle high band component and the low band component of the left channel
by the analog HPF (high pass filter) 151 and the analog LPF (low pass filter) 152.
[0109]
The signal of the middle high band component of the left channel from the analog HPF 151 is
supplied to the laminated piezoelectric actuator 70L, and the signal of the low band component
of the left channel from the analog LPF 152 is supplied to the speaker unit 120L.
[0110]
On the other hand, the signal SR of the right channel is amplified by the audio amplification
circuit 145 and then separated into the middle high frequency component and the low frequency
component of the right channel by the analog HPF (high pass filter) 155 and the analog LPF (low
pass filter) 156.
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[0111]
The signal of the middle high band component of the right channel from the analog HPF 155 is
supplied to the laminated piezoelectric actuator 70R, and the signal of the low band component
of the right channel from the analog LPF 156 is supplied to the speaker unit 120R.
[0112]
The laminated piezoelectric actuators 70L and 70R are voltage driven, and the speaker units
120L and 120R are current driven.
Therefore, the entire speaker system is designed such that DCR (direct current resistance) of the
speaker units 120L and 120R is selected so that sound pressure matching between the laminated
piezoelectric actuators 70L and 70R and the speaker units 120L and 120R can be obtained.
[0113]
The frequency characteristics of the analog LPFs 152 and 156 are flat in the low band as shown
in FIG.
[0114]
In the frequency characteristics of the analog HPFs 151 and 155, as shown in FIG. 5 or FIG. In
this case, as shown by the solid line in FIG. 15B, the pass level becomes smaller as the frequency
becomes higher in the middle and high frequency ranges.
[0115]
Note that the process of dropping the high frequency band can be performed not by the analog
HPFs 151 and 155 but by the DSP 130 at the previous stage.
[0116]
(4−2.
Another Example of Fourth Embodiment: FIG. 16 FIG. 16 shows another example of the speaker
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system of the fourth embodiment.
This example is the same as the example of FIG. 14 except for the speaker driving method.
[0117]
As a speaker driving method, in this example, in the DSP 130, the signal of the middle high band
component of the left channel, the signal of the low band component of the left channel, the
signal of the middle high band component of the right channel, and the signal of the low band
component of the right channel , To handle separately.
[0118]
The signal of the middle high frequency component of the left channel is converted to an analog
signal SLH by the DSP 130 after digital processing by the DSP 130, amplified by the audio
amplification circuit 161, and supplied to the multilayer piezoelectric actuator 70L.
[0119]
The low frequency component signal of the left channel is converted to an analog signal SLL by
the DSP 130 after digital processing by the DSP 130, amplified by the audio amplification circuit
162, and supplied to the speaker unit 120L.
[0120]
The signal of the middle high band component of the right channel is converted to an analog
signal SRH by the DSP 130 after digital processing by the DSP 130, amplified by the audio
amplification circuit 165, and supplied to the multilayer piezoelectric actuator 70R.
[0121]
The low frequency component signal of the right channel is converted to an analog signal SRL by
the DSP 130 after digital processing by the DSP 130, amplified by the audio amplification circuit
166, and supplied to the speaker unit 120R.
[0122]
In this example, the DSP 130 performs processing for dropping high frequencies as shown in
FIG.
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[0123]
In this example, for example, a time difference of several milliseconds to several tens of
milliseconds is provided between the signals supplied to the laminated piezoelectric actuators
70L and 70R and the signals supplied to the speaker units 120L and 120R, thereby reducing the
low frequency components. By delaying the signal of (1), it is possible to enhance the sound
image localization effect on the display screen by the Haas effect.
[0124]
[5.
Other Embodiments or Example: FIG. 17] (5-1.
About the Structure: FIG. 17 The above-mentioned examples are the case where the structure
functioning as an acoustic diaphragm is a frame plate-like (frame-like) bezel 10, but the structure
does not necessarily have to be a frame plate-like .
[0125]
FIG. 17 shows an example where the structure is not a frame plate but a rectangular flat plate.
Fig. 17 (A) is a front view of the speaker system, and Fig. 17 (B) shows a cross section at the
position of line Y in Fig. 17 (A).
[0126]
In this example, a transparent rectangular flat plate such as an acrylic plate is provided as the
front panel 80, and the display panel 40 and the laminated piezoelectric actuators 70L and 70R
are attached to the back side thereof.
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The laminated piezoelectric actuators 70L and 70R are attached to the front panel 80 on the left
and right sides of the display screen 41.
[0127]
In this case, the portion of the front panel 80 located in front of the display screen 41 needs to
be transparent, but if it is transparent up to the upper, lower, left and right peripheral portions,
the laminated piezoelectric actuators 70L and 70R etc. can be seen from the front side It's bad, it
looks bad.
[0128]
Therefore, on the front surface of the front panel 80, a film 81 is formed on the peripheral
portion of the display screen 41 to make the portion opaque.
[0129]
(5−2.
Regarding the Actuator Each of the examples described above is the case where a laminated
piezoelectric actuator is used as the actuator, but a super-magnetostrictive actuator, an
electrostatic actuator, or the like can also be used as the actuator.
[0130]
Further, as a mounting configuration of the actuator, for example, a square hole may be formed
in the bezel, and the actuator may be attached to the square hole to apply vibration in the plate
surface direction to the bezel.
[0131]
(5−3.
Speaker Driving Method) As the speaker driving method, a driving method other than the abovedescribed driving method may be used according to the number and mounting position of the
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actuators, and the number and arrangement position of the speaker units when providing a
normal speaker unit. Can.
[0132]
It is the figure which looked at the bezel of an example of the speaker system of a 1st
embodiment from the back side.
It is the figure which looked at the bezel and display panel of an example of the speaker system
of 1st Embodiment from the back side.
It is a figure which shows the cross-section along the central axis of the laminated piezoelectric
actuator of an example of the speaker system of 1st Embodiment.
It is a figure showing an example of a lamination piezoelectric actuator.
It is a figure which shows the difference in the frequency characteristic by the individual
difference of a bezel.
It is a figure which shows the case where the difference of the frequency characteristic by the
individual difference of a bezel becomes small.
It is a figure which shows an example of the speaker system in the case of adding a pre-load to a
lamination | stacking piezoelectric actuator.
It is a figure which shows the actuator attachment structure of the other example of the speaker
system of 1st Embodiment.
It is a figure which shows the actuator attachment structure of the other example of the speaker
system of 1st Embodiment.
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It is a figure where it uses for description of the difference between 1st Embodiment and 2nd
Embodiment.
It is a figure which shows an example of the speaker system of 2nd Embodiment.
It is a figure which shows an example of the speaker system of 3rd Embodiment.
It is a figure which shows the other example of the speaker system of 3rd Embodiment.
It is a figure which shows an example of the speaker system of 4th Embodiment.
It is a figure which shows an example of the frequency characteristic of the filter in FIG.
It is a figure which shows the other example of the speaker system of 4th Embodiment.
It is a figure showing an example of the speaker system of this invention.
It is a figure showing the speaker apparatus shown by patent documents 1 and 2.
It is a figure which shows the speaker apparatus shown by patent document 3. FIG.
It is a figure which shows the speaker apparatus proposed by the unopened patent application.
Explanation of sign
[0133]
The main part is described in the figure, so it is omitted here.
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