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DESCRIPTION JP2008270858

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DESCRIPTION JP2008270858
An object of the present invention is to provide a directional sound system capable of realizing
surround sound effects by performing virtual sound source control in consideration of the
arrangement of surrounding buildings and objects. An ultrasonic speaker having a variable angle
mechanism for changing an angle of an acoustic emission axis of an ultrasonic transducer so as
to scan an acoustic transducer in a desired spatial area; sound of acoustic output emitted from
the ultrasonic speaker A detection intensity profile generation means for generating a detection
intensity profile in the detection target space based on the intensity of the sound output detected
by the microphone; storage means for storing the detection intensity profile; And control means
for controlling the movable range of the ultrasonic transducer with reference to the intensity
profile. [Selected figure] Figure 1
Directional sound system and projector
[0001]
The present invention uses an ultrasonic speaker capable of reproducing the signal sound of the
audio frequency band using non-linearity of the medium (air) with respect to the ultrasonic wave
and controlling the range in which the signal sound of the audio frequency band is reproduced.
The present invention relates to a directional sound system and a projector equipped with the
directional sound system.
[0002]
Currently, there are several types of sound systems that can reproduce real sounds.
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1
One of them is a surround system using a DVD (Digital Versatile Disk) as a sound source and an
image source. Since this DVD system is recorded in Dolby Digital format, if it reproduces
according to Dolby Digital format, a realistic sound can be realized.
[0003]
However, this system requires a total of five speakers below the screen for displaying an image,
behind the listener, for deep bass, and for left and right. Therefore, in the case of playing in the
Dolby Digital system, the cost becomes expensive to procure the equipment, and a space for
installing a large number of speakers is required, and the wiring with the installed speakers also
becomes complicated. Met.
[0004]
Therefore, voice output devices and methods have been proposed that can produce realistic
effects such as a speaker displayed on the screen can be realized with a small number of
speakers, and are attached to a projector that projects an image. The audio | voice output
apparatus and method which a viewer can experience a surround sound effect easily by the
speaker with high directivity are proposed (for example, refer patent document 1). Japanese
Patent Laid-Open No. 2000-23281
[0005]
In general, in a speaker system using ultrasonic waves, there are a method of applying ultrasonic
waves directly so that only the viewer can hear, and a method of applying sound waves to a
screen or a wall and listening to the sound reflected there ( Patent Document 1). In the latter
method, if the size of the screen is predetermined, the sound waves will fly within a limited range.
Therefore, it is difficult to create a surround effect accurately and efficiently by moving the
position of a virtual sound source generated by ultrasonic waves in a wide range.
[0006]
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For example, even if it is possible to freely change the position of the virtual sound source, if
there is an object with poor reflectivity or an object with a complicated shape around the screen,
the sound wave is reflected in an unexpected direction, It causes the sound effects to be
disturbed. In particular, when sound waves are applied to the inner wall or the like of a house,
there are many cases in which an object is placed along the wall or an object is suspended from
the wall, which may cause disturbance of the acoustic effect.
[0007]
The present invention has been made in view of such circumstances, and realizes surround sound
effects by performing virtual sound source control in consideration of the arrangement of
surrounding structures and objects using an ultrasonic transducer. It is an object of the present
invention to provide a directional sound system that can be used and a projector equipped with
the same.
[0008]
In order to achieve the above object, the directional sound system of the present invention has a
variable angle mechanism for changing the angle of the sound emission axis of the ultrasonic
transducer so as to scan the acoustic output of the ultrasonic transducer in a desired spatial area
It is characterized by having an ultrasonic speaker.
[0009]
In the directional sound system according to the present invention of the above configuration,
the desired angular space of the ultrasonic speaker is changed to scan the acoustic output of the
ultrasonic speaker in a desired spatial region by the variable angle mechanism. The sound
pressure of the reflected wave of the sound output in the area is detected, and the detected
intensity profile is acquired.
The movable range of the ultrasonic transducer is controlled based on the detected intensity
profile.
Therefore, by performing virtual sound source control in consideration of the arrangement of
surrounding buildings and objects, surround sound effects can be realized in the desired spatial
region.
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[0010]
Further, according to the directional sound system of the present invention, there is provided an
ultrasonic speaker having a variable angle mechanism for changing an angle of a sound wave
emission axis of the ultrasonic transducer so as to scan the ultrasonic transducer in a desired
spatial region; And a microphone for detecting the sound pressure of the reflected wave of the
sound wave emitted from the microphone.
[0011]
In the directional sound system according to the present invention of the above configuration,
the desired angular space of the ultrasonic speaker is changed to scan the acoustic output of the
ultrasonic speaker in a desired spatial region by the variable angle mechanism. The sound
pressure of the reflected wave of the sound output in the area is detected by the microphone, and
the detected intensity profile is acquired.
The movable range of the ultrasonic transducer is controlled based on the detected intensity
profile. Therefore, by performing virtual sound source control in consideration of the
arrangement of surrounding buildings and objects, surround sound effects can be realized in the
desired spatial region.
[0012]
Further, according to the directional sound system of the present invention, there is provided an
ultrasonic speaker having a variable angle mechanism for changing an angle of a sound wave
emission axis of the ultrasonic transducer so as to scan the ultrasonic transducer in a desired
spatial region; A microphone for detecting the sound pressure of the sound output emitted from
the light source, and detection intensity profile generation means for generating a detection
intensity profile in the detection target space based on the intensity of the sound output detected
by the microphone. Do.
[0013]
In the directional sound system according to the present invention of the above configuration,
the desired angular space of the ultrasonic speaker is changed to scan the acoustic output of the
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ultrasonic speaker in a desired spatial region by the variable angle mechanism. The sound
pressure of the reflected wave of the sound output in the area is detected by the microphone.
The detection strength profile generation means generates a test strength profile in the space to
be detected based on the strength of the sound output detected by the microphone, and acquires
the detection strength profile. The movable range of the ultrasonic transducer is controlled based
on the detected intensity profile. Therefore, by performing virtual sound source control in
consideration of the arrangement of surrounding buildings and objects, surround sound effects
can be realized in the desired spatial region.
[0014]
Further, according to the directional sound system of the present invention, there is provided an
ultrasonic speaker having a variable angle mechanism for changing an angle of a sound wave
emission axis of the ultrasonic transducer so as to scan the ultrasonic transducer in a desired
spatial region; A microphone for detecting the sound pressure of the sound output emitted from
the target, detection intensity profile generation means for generating a detection intensity
profile in the detection target space based on the intensity of the sound output detected by the
microphone, and the detection intensity profile And storage means for storing.
[0015]
In the directional sound system having the above configuration, the sound emission axis of the
ultrasonic speaker is changed to scan the acoustic output of the ultrasonic speaker in a desired
spatial region by the variable angle mechanism, thereby obtaining the desired spatial region. The
sound pressure of the reflected wave of the sound output is detected by the microphone.
The detection intensity profile generation means generates a test intensity profile in the space to
be detected based on the intensity of the sound output detected by the microphone, and the
detection intensity profile is stored in the storage means. The movable range of the ultrasonic
transducer is controlled based on the detected intensity profile stored in the storage means.
Therefore, by performing virtual sound source control in consideration of the arrangement of
surrounding buildings and objects, surround sound effects can be realized in the desired spatial
region.
[0016]
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Further, according to the directional sound system of the present invention, there is provided an
ultrasonic speaker having a variable angle mechanism for changing an angle of a sound wave
emission axis of the ultrasonic transducer so as to scan the ultrasonic transducer in a desired
spatial region; A microphone for detecting the sound pressure of the sound output emitted from
the target, detection intensity profile generation means for generating a detection intensity
profile in the detection target space based on the intensity of the sound output detected by the
microphone, and the detection intensity profile It has a storage means to preserve | save, It is
characterized by having a control means which controls the movable range of the said ultrasonic
transducer with reference to the said detection intensity profile.
[0017]
The sound pressure of the reflected wave of the acoustic output in the desired space area is
changed by changing the sound emission axis of the ultrasonic speaker to scan the sound output
of the ultrasonic speaker in the desired space area by the variable angle mechanism. It detects by
the said microphone.
The detection intensity profile generation means generates a test intensity profile in the space to
be detected based on the intensity of the sound output detected by the microphone, and the
detection intensity profile is stored in the storage means. The movable range of the ultrasonic
transducer is controlled based on the detected intensity profile stored in the storage means.
Therefore, by performing virtual sound source control in consideration of the arrangement of
surrounding buildings and objects, surround sound effects can be realized in the desired spatial
region.
[0018]
Also, the projector according to the present invention projects an image onto a projection
surface, an ultrasonic speaker having a variable angle mechanism that changes the angle of the
sound wave emission axis of the ultrasonic transducer so as to scan the ultrasonic transducer in a
desired spatial area. And a projection optical system.
[0019]
In the projector according to the present invention of the above configuration, the sound
emission axis of the ultrasonic speaker is changed so as to scan the acoustic output of the
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ultrasonic speaker in a desired spatial region by the variable angle mechanism. The sound
pressure of the reflected wave of the sound output is detected, and the detected intensity profile
is acquired.
The movable range of the ultrasonic transducer is controlled based on the detected intensity
profile. Therefore, by performing virtual sound source control in consideration of the
arrangement of surrounding buildings and objects, surround sound effects can be realized in the
desired spatial region.
[0020]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings. FIG. 2 shows the appearance of a directional sound system according to an
embodiment of the present invention. In the present embodiment, as an example of a directional
sound system, a case is described where it is applied to a projector that outputs sound and
displays an image on a screen. FIG. 2A is a front view of the projector, and FIG. 2B is a side view
of the projector.
[0021]
In FIG. 2, the projector 1 is provided with ultrasonic speakers 2A and 2B. The ultrasonic speakers
2A and 2B are beam-like sound sources having very strong directivity, and can generate
relatively small sound waves having a relatively wide spread, as indicated by dotted arrows a in
the figure. In addition, an image is projected forward from the projector 1 from a built-in
projection optical system as indicated by a symbol c.
[0022]
The ultrasonic speakers 2A and 2B have a transducer angle varying mechanism 6 which can
change the direction of the sound wave. The transducer angle varying mechanism 6 has a
function of varying the angle of the sound wave emission axis of the ultrasonic speaker 2 housed
in the holder 7.
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[0023]
Next, FIG. 1 shows the electrical configuration of the projector shown in FIG. In FIG. 1, the
projector 1 includes a transducer angle variable mechanism 6, an audio / video signal
reproduction unit 10, an audio signal processing unit 11, a carrier wave oscillation source 12,
modulators 13A and 13B, and a power amplifier 14A, 14B, ultrasonic transducers 15A, 15B,
speaker setting unit 16, volume control units 17A, 17B, virtual sound source control unit 20,
sound pressure measurement microphone 21, detection intensity profile generation circuit 22,
data storage The projector 23 includes an image generation unit 250 that generates an image
built in the projector 1, and a projection optical system 251 that projects the generated image.
Although only one transducer angle varying mechanism 6 is shown in FIG. 1 for convenience of
explanation, it is assumed that the transducer angle varying mechanism 6 is actually provided in
each of the ultrasonic transducers 15A and 15B. The carrier wave oscillation source 12, the
modulator 13A, the power amplifier 14A and the ultrasonic transducer 15A constitute an
ultrasonic speaker 2A. The carrier wave oscillation source 12, the modulator 13B, the power
amplifier 14B and the ultrasonic transducer 15B constitute an ultrasonic speaker 2B.
[0024]
The audio / video signal reproduction unit 10 has a function of reproducing an audio signal and
a video signal. The audio signal processing unit 11 has a function of analyzing the generation
position, frequency, sound effect and the like of audio from the input audio signal, and
transmitting it to the signal system of the ultrasonic speaker 2. The audio signal processing unit
11 includes a sound source direction analysis unit 110, a frequency analysis unit 111, and an
acoustic effect analysis unit 112.
[0025]
The sound source direction analysis unit 110 has a function of detecting from the audio signal
the generation position of each sound, that is, the front, rear and side sound positions with
reference to the position of the viewer. The frequency analysis unit 111 has a function of
analyzing the frequency band of the input audio signal, for example, whether it is a low
frequency region or a high frequency region. The sound effect analysis unit 112 has a function of
analyzing the sound effect from the input audio signal. Specifically, signal detection is performed
on the presence of fade-in, fade-out, Doppler effect, loud sound, silent noise and the like.
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[0026]
The carrier wave oscillation source 12 has a function of generating a carrier wave in an
ultrasonic frequency band. The modulators 13A and 13B modulate the carrier wave output from
the carrier wave oscillation source 12 with the audio signal (signal wave) in the audible
frequency band output from the audio signal processing unit 11. An example of a specific
configuration of the ultrasonic transducers 15A, 15B constituting the ultrasonic speakers 2A, 2B
is shown in FIG. FIG. 3A is a view showing a cross-sectional structure of the electrostatic
ultrasonic transducer. The electrostatic ultrasonic transducer shown in FIG. 3A is sandwiched
between a pair of fixed electrodes 40 and 41 including a conductive member formed of a
conductive material functioning as an electrode, and a pair of fixed electrodes 40 and 41, A
vibrating membrane 42 having a conductive layer (diaphragm electrode) 421 and a support
member 45 for holding the pair of fixed electrodes 40 and 41 and the vibrating membrane 42
are included.
[0027]
The vibrating film 42 has an insulating layer 420 and a conductive layer 421 formed of a
conductive material, and the conductive layer 421 has either a single polarity (positive or
negative polarity) by the DC bias power supply 46. Or the like) may be applied.
[0028]
Further, the pair of fixed electrodes 40 and 41 have the same number and a plurality of through
holes 44 at the positions facing each other through the vibrating film 42, and between the
conductive members of the pair of fixed electrodes 40 and 41, the signal source 48A, An
alternating current signal is applied by 48B.
Capacitors are formed on the fixed electrode 40 and the conductive layer 421, and the fixed
electrode 41 and the conductive layer 421, respectively.
[0029]
In the above configuration, the electrostatic ultrasonic transducer 15A (or 15B) applies a DC bias
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voltage of a single polarity (in this example, a positive polarity) to the conductive layer 421 of the
diaphragm 42 by the DC bias power supply 46. . On the other hand, an alternating current signal
is applied to the pair of fixed electrodes 40 and 41 by the signal sources 48A and 48B. As a
result, in the positive half cycle of the alternating current signal output from the signal sources
48A and 48B, a positive voltage is applied to the fixed electrode 40, so the surface portion 43A
of the vibrating film 42 not held by the fixed electrodes is The electrostatic repulsion acts on the
surface portion 43A, and the surface portion 43A is pulled downward in FIG. Further, at this
time, since a negative voltage is applied to the fixed electrode 41 opposed thereto, an
electrostatic attractive force acts on the back surface portion 43B which is the back surface side
of the vibrating film 42, and the back surface portion 43B is In FIG. 3, it is pulled further
downward.
[0030]
Therefore, the film portion of the vibrating film 42 which is not sandwiched by the pair of fixed
electrodes 40 and 41 receives electrostatic repulsion and electrostatic attraction in the same
direction. The same applies to the negative half cycle of the alternating current signal output
from the signal sources 48A and 48B, in the surface portion 43A of the vibrating membrane 42,
in FIG. In Fig. 3, electrostatic repulsion acts on the upper side, and the membrane part of
diaphragm 42 not held by the pair of fixed electrodes 40 and 41 has electrostatic repulsion and
electrostatic attraction in the same direction. receive. In this manner, the diaphragm 42 receives
the electrostatic repulsion and the electrostatic attraction in the same direction according to the
change of the polarity of the AC signal, and the direction in which the electrostatic force acts
alternately changes, so that a large membrane vibration That is, an acoustic signal at a sound
pressure level sufficient to obtain a parametric array effect can be generated.
[0031]
As described above, the ultrasonic transducer shown in FIG. 3 is called a push-pull type because
the vibrating membrane 42 vibrates by receiving a force from the pair of fixed electrodes 40 and
41. Push-pull electrostatic ultrasonic transducers have the ability to simultaneously satisfy
broadband and high sound pressure, compared to pull-type electrostatic ultrasonic transducers
that only act on the vibrating film. have.
[0032]
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As described above, in the push-pull type electrostatic ultrasonic transducer, a high voltage DC
bias voltage is applied to the vibrating film, and an alternating voltage is applied to the fixed
electrode, whereby the fixed electrode-vibration film is obtained. The membrane portion vibrates
due to the electrostatic force (attractive force and repulsive force) acting on the In this case, in
order to realize the vibration of the ultrasonic band, it is necessary to set the hole diameter of the
vibrating portion to several mm or less. For example, as shown in FIG. By providing the vibration
hole 44, it is necessary to configure a transducer having a high tracking ability and a large
output.
[0033]
In addition, the speaker setting unit 16 takes in the voice signal input from the voice signal
processing unit 11 and each analysis result of the sound source direction analysis unit 110, the
frequency analysis unit 111, and the sound effect analysis unit 112, While setting to select a
speaker for generating this, and sending volume control information for setting the volume of
each speaker to the volume control units 17A and 17B, the ultrasonic transducer 15A (or 15B) is
variable in transducer angle. Control information for performing drive control via the mechanism
unit 6 is sent to the virtual sound source control unit 20. The ultrasonic transducers 15A, 15B
have a transducer angle varying mechanism 6. The transducer angle varying mechanism 6 has a
function of changing the angle of the sound wave emission axis of the ultrasonic transducer so as
to scan the acoustic transducer 15 in a desired step in a predetermined step under the control of
the virtual sound source control unit 20. doing.
[0034]
FIG. 4 shows an example of an electromagnetic actuator system as an example of the transducer
angle variable mechanism 6 that changes the angle of the sound wave emission axis of the
ultrasonic transducer, and shows the center cross section of the transducer angle variable
mechanism 6 It is a thing. The mechanical configuration is the same for both ultrasonic speakers
2A and 2B, so only ultrasonic speaker 2A will be described here. The ultrasonic speaker 2A has
an ultrasonic transducer 15A for emitting ultrasonic waves, and the ultrasonic transducer 15A is
housed in a spherical holder 7 made of nonmagnetic material, and a small portion of a small
piece is formed at the center of the back surface of the holder 7 A magnetic plate 33 which is a
soft magnetic material is embedded. The back surface of the holder 7 is provided with a
magnetizing device 34 capable of magnetizing a desired position at a predetermined interval.
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[0035]
Therefore, when it is desired to rotate the ultrasonic transducer 15A in the direction of the arrow
A and change it to a specific direction, the magnetic plate 33 embedded in the holder 7 is
attracted by moving the magnetizing position by the magnetizing device 34. To the desired
position.
[0036]
FIG. 4B is an example in which the ultrasonic transducer 15A is rotated 45 degrees left and held,
and FIG. 4C is an example in which the ultrasonic transducer 15A is held at the central position,
and FIG. Shows an example in which the ultrasonic transducer 15A is rotated 45 degrees to the
right and held.
[0037]
The transducer angle variable mechanism 6 shown in FIG. 4 is an example of an electromagnetic
actuator system using the magnetic plate 33 and the magnetizing device 34, but may be a
mechanism using a motor and a gear.
Further, FIG. 4 shows the ultrasonic transducer 15A only in the example of FIG. 4 rotating only in
the direction of arrow A, but the ultrasonic transducer 15 is not only in the direction of arrow A,
but also in the direction perpendicular to the paper It is also easy to use a mechanism that can
rotate.
[0038]
The volume control units 17A and 17B set the gains of the power amplifiers 14A and 14B based
on the volume control information output from the speaker setting unit 16, and thereby control
the volume of the ultrasonic speakers 2A and 2B.
The sound pressure measurement microphone 21 detects the sound pressure of the sound
output emitted from the ultrasonic speakers 2A and 2B. The sound pressure measurement
microphone 21 corresponds to the microphone of the present invention.
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[0039]
The detection intensity profile generation circuit 22 generates a detection intensity profile in the
detection target space based on the intensity of the acoustic output detected by the sound
pressure measurement microphone 21. The detection intensity profile generation circuit 22
corresponds to the detection intensity profile generation means of the present invention.
[0040]
The data storage unit 23 has a function of storing the detected intensity profile. The data storage
unit 23 corresponds to the storage unit of the present invention. The virtual sound source control
unit 20 controls the movable range of the ultrasonic transducer 15 with reference to the
detected intensity profile via the transducer angle variable mechanism unit 6. The virtual sound
source control unit 20 corresponds to the control means of the present invention.
[0041]
Next, the flow of detection intensity profile generation will be described. In the above
configuration, by driving and controlling the transducer angle variable mechanism 6, the angle of
the sound wave emission axis of the ultrasonic transducer 15A (or the ultrasonic transducer 15B)
is changed in predetermined angular steps via the transducer angle variable mechanism 6. The
ultrasonic waves emitted from the ultrasonic transducer 15A (or the ultrasonic transducer 15B)
are scanned in a desired spatial area by causing them to be transmitted. The ultrasonic wave
transmitted from the ultrasonic transducer 15A (or the ultrasonic transducer 15B) at each setting
position is usually reflected by a screen, a wall or the like, and the sound pressure is measured by
the sound pressure measurement microphone 21. Based on this, the detection intensity profile
generation circuit 22 generates a detection intensity profile. The generated detection intensity
profile is stored in the data storage unit 23.
[0042]
Here, as shown in FIG. 5, when the above measurement is performed on a wall having a general
U-shaped structure, it is perpendicular to the wall (= a scanning angle of 0 degree, the starting
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point is here) When an ultrasonic wave is emitted from the ultrasonic transducer 15A (or the
ultrasonic transducer 15B), the reflected wave is detected by the sound pressure measurement
microphone 21 with an extremely high sound pressure. Also, if the sound is not emitted
perpendicularly to the wall, the sound pressure is measured by the sound pressure measurement
microphone 21 after repeated reflections by the surrounding wall or object, so attenuation of
ultrasonic waves due to repeated reflections occurs, but it is stable. Sound pressure that can be
measured.
[0043]
On the other hand, as shown in FIG. 6, when there is an ultrasonic absorber such as a urethane
type object that absorbs ultrasonic waves or a cloth that is difficult to reflect in the measurement
area, the ultrasonic waves are significantly attenuated and stable. Detection is difficult, and the
detection intensity is very low. Also, even if there is no device that absorbs ultrasonic waves in
the direction in which the ultrasonic waves are transmitted, if there is a device that absorbs
ultrasonic waves before the reflection is repeated, the sound pressure measurement microphone
The sound pressure intensity detected at 21 may significantly decrease, and the pressure
measurement state also becomes unstable.
[0044]
As described above, it is not possible to form a sufficient sound field even when sound waves are
transmitted to the position (angle) at which the sound detection intensity significantly decreases
by the sound pressure measurement microphone 21. Therefore, the virtual sound source control
unit 20 controls the transducer angle variable mechanism unit 6 that changes the angle of the
sound wave emission axis of the ultrasonic transducers 15A and 15B in the ultrasonic speaker 2
while avoiding this position (angle). Based on the detected intensity profile thus generated and
stored, the sound source radiation axis of the ultrasonic transducers 15A and 15B through the
transducer angle variable mechanism 6 while considering the surrounding structure in the
virtual sound source control unit 20. By changing the angle of, it is possible to localize the sound
source according to the surrounding environment, and create a reliable surround effect.
[0045]
FIG. 7A shows the case where the sound waves of the left and right ultrasonic speakers 2A and
2B are generated at a right angle to the projector 1 (similar to FIG. 4A), and the individual
ultrasonic speakers 2A and 2B are generated. The sound wave of is reflected at each arrival
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position, and the sound wave of the audible range like f in the figure is reproduced.
[0046]
FIG. 7 (b) shows the case where the sound waves of the left and right ultrasonic speakers 2A and
2B are generated by inclining both the projector 1 inward, and the sound waves of the respective
ultrasonic speakers 2A and 2B reach the same The sound is reflected at the position, and as
shown by g in the figure, the sound wave in the audible range concentrated in the front area to
the projector 1 is reproduced.
Thus, the volume of the reproduced sound can be increased, which is effective in creating a sense
of reality.
[0047]
FIG. 7C shows the case where the sound waves of the left and right ultrasonic speakers 2A and
2B are generated by being inclined outward with respect to the projector 1, and the sound waves
of the individual ultrasonic speakers 2A and 2B reach their respective Sound waves in the audible
range that are reflected at positions and diffuse further outward as shown by h in the figure are
reproduced. Therefore, when the position of the sound source of a certain video scene is
diagonally forward, sound image localization can be performed by the above method.
[0048]
Further, in a certain video scene, when the sound source is at the upper side or the side, the
ultrasonic wave reflected by the front wall is largely inclined by largely generating the sound
wave of the ultrasonic speaker 2A (or the ultrasonic speaker 2B). It can also be reflected by the
ceiling or side walls to reproduce sound waves in the audible range.
[0049]
In addition, by using the transducer angle variable mechanism 6 of two or one ultrasonic
speaker, it is possible to produce a state in which sound flows up and down or left and right, or a
state in which sound circulates.
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Further, in the transducer angle variable mechanism portion of the ultrasonic speaker according
to the embodiment of the present invention, it is possible to directly irradiate ultrasonic waves
not only to the wall behind the viewer but also to the wall up and down or to the side. It is also
possible to produce more complex and colorful sound effects.
[0050]
FIG. 1 is a block diagram showing the configuration of a projector as a directional sound system
according to an embodiment of the present invention. FIG. 2 is an explanatory view showing an
appearance configuration of the projector shown in FIG. 1; FIG. 2 is a view showing an example
of a specific configuration of the ultrasonic transducer in FIG. 1; FIG. 2 is an explanatory view
showing a configuration of a transducer angle variable mechanism in FIG. 1; Explanatory drawing
which shows one Example of the measurement for acquiring the detection intensity profile of the
reflected wave of the acoustic output radiated from the ultrasonic transducer in the desired space
area | region. Explanatory drawing which shows the other Example of the measurement for
acquiring the detection intensity profile of the reflected wave of the acoustic output radiated
from the ultrasonic transducer in the desired space area | region. Explanatory drawing which
shows the various reproduction | regeneration states in, when the direction of the sound wave
radiated | emitted from the ultrasonic speaker in the projector which concerns on embodiment of
this invention is made changeable.
Explanation of sign
[0051]
DESCRIPTION OF SYMBOLS 1 ... Projector, 2A, 2B ... Ultrasonic speaker, 6 ... Transducer angle
variable mechanism part, 10 ... Audio / video signal reproduction part, 11 ... Audio signal
processing part, 12 ... Carrier wave oscillation source, 13A, 13B ... Modulator, 14A, 14B: power
amplifier, 15A, 15B: ultrasonic transducer, 16: speaker setting unit, 17A, 17B: volume control
unit, 20: virtual sound source control unit, 21: microphone for measuring sound pressure, 22:
detection intensity profile generation Circuit, 23: data storage unit, 250: image generation unit,
251: projection optical system
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