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JP2006339954

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DESCRIPTION JP2006339954
PROBLEM TO BE SOLVED: To provide an acoustic screen capable of providing a realistic sound
effect without making a hole in the screen. SOLUTION: A screen has a screen surface for
displaying image information, a piezoelectric layer formed on the back surface of the screen
surface, a means for supplying power to the piezoelectric layer, and a means for modulating the
supplied power according to an acoustic signal. And [Selected figure] Figure 1
Screen and image projection system
[0001]
The present invention relates to an acoustic screen that projects an optical image from a
projector such as a liquid crystal projector and the like and simultaneously emits sound, and an
image projection system that displays an image using this screen.
[0002]
An image projection system such as a projection apparatus that displays an image by projecting
an optical image using a high brightness CRT or a liquid crystal projector can easily display a
large screen and a high definition image, so information with a plurality of users can be obtained.
It has come to be used in various ways as a communication tool.
The projector screen has a structure in which a white material having a high light reflectance or
a light reflection film is coated on the surface to improve light utilization efficiency, or beads are
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dispersed on the surface to diffuse light by a plurality of observers. Devices have been devised to
improve the visibility of
[0003]
In addition, audio information, which is important information at the same time as video, is
supplied by a speaker provided behind the screen or a speaker placed on the ceiling or floor
avoiding the screen. In particular, when a speaker is placed behind the screen, a realistic video
can be produced because the video source and the sound source match, but the screen does not
block the sound and the clear audio is supplied. In order to do this, there is disclosed a technique
for forming a hole on the screen surface corresponding to the speaker positions disposed on the
left and right (for example, Patent Document 1). Furthermore, techniques such as using a screen
or a textile screen in which innumerable micro holes are formed on the entire screen have been
known from old times. JP-A-9-325421 public information (page 3, FIG. 1)
[0004]
However, the conventional acoustic screen has a problem that the image projection area becomes
narrow in order to perform processing for making holes in the screen. Furthermore, opening
innumerable micro holes on the entire screen surface has been a cause of increasing the cost of
the screen because it is technically advanced. Furthermore, when using a textile screen, it had the
subject that it was difficult to control optical characteristics, such as screen gain and directivity.
Thus, the present invention provides an acoustic screen that can provide a realistic sound effect
without making holes in the screen.
[0005]
In order to solve the above problems, the screen of the present invention comprises a screen
surface for displaying image information, a piezoelectric layer formed on the back surface of the
screen surface, means for supplying power to the piezoelectric layer, and a piezoelectric layer
Means for modulating the power supplied to the signal in accordance with the acoustic signal.
With such a configuration, it is possible to output sound directly from the screen surface without
making a hole in the screen surface, and it is possible to create a realistic sound effect because
the sound source is on the screen .
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[0006]
Further, the area where the piezoelectric layer is formed is divided into a plurality of areas on the
back surface of the screen surface, and sound signals independent of each other are given to the
divided areas. With such a configuration, it is possible to generate an arbitrary acoustic signal
from an arbitrary position on the screen surface, and as a result, a more realistic acoustic effect
can be realized.
[0007]
As the piezoelectric layer, a polymer film having piezoelectricity, in particular, a piezoelectric
fluoride resin film such as PVDF or PVF 2 is used. By using these piezoelectric polymer films,
sound can be output while maintaining the flexibility of the screen. Furthermore, since the
fluoride resin film is a translucent film, the use of the screen of the present invention as a
transmission screen does not affect the optical characteristics.
[0008]
Since the screen of the present invention can output an acoustic signal directly from the screen
surface, it can create a highly realistic sound effect. Further, as a result, since the speaker
installation place is not necessary, there is also an effect that the screen environment space can
be efficiently used.
[0009]
In addition, by dividing the piezoelectric layer on the back surface of the screen surface, sound
can be generated from any place on the screen, which has an effect of enhancing the sense of
reality. For example, this effect can be further enhanced by previously setting the
correspondence between the sound generation place and the image information to be displayed
at the time of production of the video information. Of course, it is also possible to obtain a threedimensional sound effect by inputting a stereo signal to a sound generation position shifted to
the left and right.
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[0010]
In the screen of the present invention, a piezoelectric layer and an electrode for supplying power
to the piezoelectric layer are formed on the back side of the screen surface on which image
information is displayed. The modulation circuit supplies to the electrode a voltage modulated
according to the audio signal supplied from the sound source circuit. As a result, the piezoelectric
layer vibrates according to the modulation voltage to generate sound.
[0011]
The electrode includes a first drive electrode and a second drive electrode sandwiching the
piezoelectric layer, and at least one drive electrode may be divided into a plurality of regions. In
that case, the same audio signal may be supplied to some of the electrodes divided into a
plurality of regions, or different audio signals may be supplied to each other.
[0012]
Further, the image projection system of the present invention includes the screen having the
above-described configuration, and an optical image projector which projects an optical image on
the screen. In such an image projection system, it is not necessary to install a speaker, and an
acoustic effect with a high sense of reality can be obtained.
[0013]
Hereinafter, embodiments of the screen will be described in detail.
[0014]
The acoustic screen of the present embodiment will be described based on FIG.
Fig.1 (a) is a schematic diagram which shows the structure of the side of an acoustic screen, FIG.1
(b) is a schematic diagram which shows the structure of the front side of an acoustic screen. As
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shown in FIG. 1B, in the acoustic screen of this embodiment, a piezoelectric layer 2 is provided
on the back surface of the screen surface 1, and the piezoelectric layer 2 is opposed to each
other by a first drive electrode 3 and a second drive electrode. It has a structure sandwiched by
four. As the piezoelectric layer 2, inorganic piezoelectric ceramics such as PZT and PLZT having a
large piezoelectric constant, and piezoelectric polymer films such as PVDF and PVF 2 can be
used. By using a transparent piezoelectric material such as PLZT, PVDF, or PVF 2 for the
piezoelectric layer 2 and using transparent electrodes for the first drive electrode 3 and the
second drive electrode 4, sound is not affected by the optical characteristics of the screen. Can be
generated. The use of this transparent piezoelectric layer is effective when the screen of the
present invention is used as a rear screen for displaying an image by irradiating projection light
from the back side. In addition, by using the above-mentioned piezoelectric polymer film as the
piezoelectric layer 2, it is possible to obtain a screen having excellent mechanical strength and
which can be rolled up.
[0015]
The piezoelectric layer 2 can generate an arbitrary sound by applying a signal voltage from an
external sound signal source between the first drive electrode 3 and the second drive electrode 4.
As shown in FIG. 1, the drive circuit is constituted by the power supply 5, the modulation circuit
6, the sound source circuit 7, and the connections 9 to 13 which electrically connect these. And
one end of this drive circuit is dropped to the ground 8. The sound source circuit 7 is an audio
circuit of a projector (not shown), an audio circuit of an audiovisual disk driver, or the like, and
supplies an audio signal corresponding to an image projected on the screen to the modulation
circuit 6. The modulation circuit 6 modulates the voltage applied to the piezoelectric layer 2 in
accordance with the audio signal supplied from the sound source circuit 7. As a result, the
piezoelectric layer 2 vibrates in accordance with the modulation voltage to generate audio. The
power supply 5 supplies power to this drive circuit.
[0016]
As described above, in the screen of this embodiment, it is not necessary to dispose a speaker on
the side surface or the back surface of the screen in order for the piezoelectric layer formed on
the back surface of the screen to vibrate to generate sound. In addition, since the sound source is
the entire screen, the same effect as direct sound generation from the image projected on the
screen can be produced, and a highly realistic sound effect can be created.
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[0017]
The configuration of the acoustic screen of this embodiment is schematically shown in FIG. FIG. 2
shows the view from the opposite side of the projection plane. In the screen of this embodiment,
the sectional structure is the same as the sectional structure of Embodiment 1, but the first drive
electrode is divided into a plurality of parts in a plane, and these divided first drive electrodes are
formed. Wirings are formed so that drive voltages are independently applied between 3a, 3b, 3c,
and 3d and the second drive electrode 4. That is, in accordance with the connection switching
signal carried on the audio signal from the sound source circuit 7, the modulation circuit 6
switches the audio signal to the wires 10a to 10c and transmits the audio signal independently.
As the transmission method, different voice signals can be sent to all the wires, or the same voice
signal can be sent to a plurality of wires. For example, the right audio signal of the stereo signal
is connected to the wirings 10a and 10d, and the left audio signal is connected to the wirings
10b and 10c. As a result, the right audio signal is applied to the right side area of the
piezoelectric layer 2 sandwiched between the first drive electrode 3a and the second drive
electrode 4 and between the first drive electrode 3d and the second drive electrode 4, and the
first drive electrode A left audio signal is applied to the left side area of the piezoelectric layer 2
sandwiched between the first drive electrode 3c and the second drive electrode 4 and the second
drive electrode 4b. In this way, the acoustic screen of the present invention can produce stereo
acoustic effects.
[0018]
Here, the case of producing stereo sound effects has been described, but using the same method,
it is possible to emit audio only from the upper part of the screen or audio from only the lower
part. For example, it is possible to determine in advance a piezoelectric layer region from which
sound is to be output corresponding to image information and to perform screening. That is, it is
also possible to move the sound emitting area according to the movement of the person on the
screen. With such a configuration, as the screen becomes larger, it becomes possible to change
the sound generation position corresponding to the finer area, and it is possible to obtain a more
natural sound effect with realism.
[0019]
Although the piezoelectric layer is divided into four rectangular regions in FIG. 2, the number of
divisions may be two or more. Furthermore, the shape of the area may not be rectangular, and
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may be triangular, hexagonal or other polygonal or circular. Furthermore, although the second
drive electrode 4 is an electrode common to all of the first drive electrodes 3a to 3d, the second
drive electrode 4 may be divided in correspondence with the first drive electrodes 3a to 3d.
Similarly, the piezoelectric layer 2 may be divided and formed corresponding to the first drive
electrodes 3a to 3d.
[0020]
As described above, since the acoustic screen of the present invention can directly generate
sound from the piezoelectric layer formed on the screen, it is possible to produce a highly
realistic acoustic effect and, at the same time, used conventionally. Speakers can be omitted.
Furthermore, by dividing the excitation region of the piezoelectric layer, it becomes possible to
select the sound generation region on the screen, and it becomes possible to obtain a highly
realistic sound effect.
[0021]
It is a schematic diagram which shows the structure of the acoustic screen by this invention. FIG.
1 is a schematic view of an acoustic screen according to the invention.
Explanation of sign
[0022]
1 screen surface 2 piezoelectric layer 3 first drive electrode 4 second drive electrode 5 power
supply 6 modulation circuit 7 sound source circuit 8 grounding
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