JP2002345077A - Stereophonic sound field creating system by ultrasonic wave speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system that can create an audible sound filed at an optional point in a space without the need for a mechanical drive mechanism. SOLUTION: Two speakers 11, 12 emit ultrasonic waves whose frequency f1 is the same but whose phases differ from each other so as to create an intense linear ultrasonic wave sound field only in a particular direction (shown in dotted lines) through the interference between them. Similarly two speakers 21, 22 emit ultrasonic waves whose frequency f2 is the same but whose phases differ from each other so as to create an intense linear ultrasonic wave sound field only in a particular direction (shown in dotted lines) through the interference between them. When a difference between the frequencies f1, f2 is selected to be a frequency within an ultrasonic wave band (20 kHz or over), an ultrasonic wave sound field with a frequency f3=|f1-f2| is created only at cross points of both the interference ultrasonic wave sound fields (auditory area). When other ultrasonic wave speaker 31 emits an ultrasonic wave resulting from superimposing an audible sound wave on the ultrasonic wave with the frequency f3, an audible tone by beat can be created in the auditory area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional sound which uses an ultrasonic speaker to supply sound only within a desired narrow range in a three-dimensional space and makes the sound inaudible in other places. Field formation system.

[0002]

2. Description of the Related Art Various methods have been devised for supplying sound only within a certain area in space. One of the methods is to use a directional loudspeaker. Among them, in addition to the usual directional loudspeaker that radiates audible sound waves in a narrow range, there is also a parametric method that superimposes audible sound waves on ultrasonic waves and radiates them in a narrow range. There are also array speakers. For example, JP 2000-36993
“Superdirective speaker device” discloses a superdirective speaker device in which a low sound pressure level, which is a weak point of a parametric array speaker, is improved.

On the other hand, a method of reproducing an audible sound only at a specific point by using a plurality of ultrasonic sound sources has been considered. For example, Japanese Patent Application Laid-Open No. 11-145915 "Ultrasonic directional loudspeaker" uses two directional ultrasonic sound sources, and one of the sound sources modulates an ultrasonic wave modulated by an audible sound, and the other sound source A method of emitting an unmodulated ultrasonic wave to form an audible sound field only at the intersection is disclosed.

[0004]

According to the method using a directional speaker, the range in which sound is supplied is linear regardless of how highly directional the speaker is used, and the sound is supplied only to point-like positions. Can not.

On the other hand, in the method disclosed in Japanese Patent Application Laid-Open No. H11-145915, although the formation of the sound field can be reduced to one point, in order to move the sound field to an arbitrary position, the directions of both ultrasonic speakers must be changed. It has to be changed mechanically and requires a complicated drive.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an audible sound at an arbitrary point in space without requiring a mechanical drive mechanism. It is to provide a system that can form a field.

[0007]

The three-dimensional sound field forming system according to the present invention, which has been made to solve the above-mentioned problems, has three parts.
One embodiment is conceivable. A first aspect is a system including the following elements. a) First transmission group. This includes the following elements: a1) Eleventh ultrasonic transmitting means for transmitting ultrasonic waves of frequency f1 a2) Twelfth transmitting ultrasonic waves having a phase shifted by θ1 from the ultrasonic waves emitted by the eleventh ultrasonic transmitting means at frequency f1 Ultrasonic transmitting means b) Second transmitting group. This includes the following elements: b1) a 21st ultrasonic wave transmitting means for transmitting an ultrasonic wave of a frequency f2 in which the difference from the frequency f1 is an ultrasonic range b2) At a frequency f2, the ultrasonic wave emitted by the 21st ultrasonic wave transmitting means has a phase. The 22nd ultrasonic wave transmitting means for transmitting the ultrasonic wave shifted by θ2 c) The audible sound superimposed transmitting the ultrasonic wave having the frequency difference of the audible sound wave with respect to the ultrasonic wave having the frequency of | f1−f2 | Sound wave transmitting means.

[0008] The second aspect is the following system. That is, a) a wide-area ultrasonic wave transmitting unit that emits a synthetic ultrasonic wave in which an audible sound is superimposed on a carrier ultrasonic wave in a wide space, and b) a portable ultrasonic wave that emits an ultrasonic wave having the same frequency as the carrier ultrasonic wave in a narrow space. And transmitting the audible sound by interference between the two ultrasonic waves only in the vicinity of the user by moving in the wide space while holding the portable ultrasonic wave transmitting means.

A third aspect is a system including the following elements. a) First transmission group. This includes the following elements: a1) The 101st ultrasonic wave transmitting means for transmitting the ultrasonic wave of the frequency f6. a2) A 102nd ultrasonic wave transmitting means for transmitting an ultrasonic wave whose phase is shifted by θ4 from the ultrasonic wave emitted by the 101st ultrasonic transmitting means at the frequency f6. b) Audible sound superimposed ultrasound transmission group. This includes the following elements: b1) 111th ultrasonic wave transmitting means for transmitting an ultrasonic wave in which an audible sound is superimposed on the ultrasonic wave of the frequency f6. b2) The phase of the ultrasonic wave emitted from the 111st ultrasonic wave transmitting means is θ5
112th ultrasonic wave transmitting means for transmitting ultrasonic waves shifted by only

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the first aspect of the present invention are as follows. Ultrasonic waves having the same frequency f1 and a phase difference of θ1 are transmitted from the two ultrasonic transmitting means (the eleventh ultrasonic transmitting means and the twelfth ultrasonic transmitting means) of the first transmitting group. . Both ultrasonic waves interfere in the space in front of them, and the intensity (amplitude) of the ultrasonic waves increases only in a certain direction. The direction K1 is determined by the following equation according to the distance L1 between the two ultrasonic wave transmitting means (the eleventh ultrasonic wave transmitting means and the twelfth ultrasonic wave transmitting means) and the phase difference θ1 (c is the speed of sound). K1 = sin ^-1 ((c ・ θ1) / (2 ・ π ・ L1 ・ f1))

Similarly, ultrasonic waves having the same frequency f2 and a phase difference of θ2 from the two ultrasonic wave transmitting means (the 21st ultrasonic wave transmitting means and the 22nd ultrasonic wave transmitting means) of the second transmission group. Are transmitted, and the two ultrasonic waves interfere with each other in the space in front of them, and the intensity (amplitude) increases only in the next direction K2 (L2 is the intensity of the 21st ultrasonic wave transmitting means and the 22nd ultrasonic wave transmitting means). Distance between). K2 = sin ^-1 ((c ・ θ2) / (2 ・ π ・ L2 ・ f2))

At the point where the interference waves from both transmission groups intersect, a beat (interference) of both interference waves occurs. Since the frequency of the interference wave from the first transmission group is f1 and the frequency of the interference wave from the second transmission group is f2, the frequency f3 of the beat generated at the intersection (referred to as “localized interference wave”) is The difference | f1−f2 |. In the present invention, since the frequency f3 is also in the ultrasonic range (ie, about 20 kHz or more), the localized interference wave itself cannot be heard by humans.

In the first aspect of the present invention, an ultrasonic transmitting means (audible sound superimposed ultrasonic transmitting means) is provided separately from the first and second transmitting groups. From this transmitting means, an ultrasonic wave in which an audible sound wave to be supplied is superimposed on the ultrasonic wave of the frequency f3 is transmitted to the same front space. As a result, at the intersection, the audible sound superimposed ultrasonic wave further interferes with the localized interference wave (causes a beat), and an audible sound that is the difference between the two ultrasonic waves is reproduced at the intersection.

In the second embodiment of the present invention, it is considered that the wide-area ultrasonic wave transmitting means is generally used in a fixed manner at a predetermined place. It is also conceivable to use it temporarily at an event venue or the like. Further, it may be one that moves together with the user holding the portable ultrasonic wave transmitting means (for example, installed on a train, a bus, or the like).

It is also possible to adopt a method of limiting the existing range of the synthesized ultrasonic wave by incorporating the concept of the first aspect of the present invention. However, in this case, unlike the case of the first embodiment, the audible sound wave to be reproduced is superimposed in advance on the synthetic ultrasonic wave.

An embodiment of the third aspect of the present invention is as follows. From the two ultrasonic transmission means (the 101st ultrasonic transmission means and the 102nd ultrasonic transmission means) of the first transmission group, the same frequency f6 as in both the transmission groups of the first embodiment. The ultrasonic wave having a phase difference of θ4 is transmitted, and the two ultrasonic waves interfere with each other in the space in front of the ultrasonic wave, and the intensity (amplitude) increases only in the next direction K3 (L3 is the 101st ultrasonic wave transmitting means And the distance between the 102nd ultrasonic wave transmitting means). K3 = sin ^-1 ((c ・ θ4) / (2 ・ π ・ L3 ・ f6))

An audible sound is superimposed from two ultrasonic transmitting means (the 111st ultrasonic transmitting means and the 112th ultrasonic transmitting means) of the audible sound superimposed ultrasonic transmitting group and has the same frequency.
An ultrasonic wave having a phase difference of θ5 at f6 (the same frequency as above) is transmitted. Both ultrasonic waves interfere with each other in the space in front of them, and the intensity (amplitude) increases only in the next direction K4 (L4 is the distance between the 111st ultrasonic transmitting means and the 112th ultrasonic transmitting means). K4 = sin ^-1 ((c ・ θ5) / (2 ・ π ・ L4 ・ f6))

At the point where the interference waves from both transmission groups intersect, a localized interference wave occurs at the intersection as in the case of the first embodiment. In this case, the generated localized interference wave itself becomes an audible sound, and is reproduced at the intersection.

Since the system according to the present invention can include various other variations in any aspect, the details will be described in detail in the following embodiments.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the first aspect of the present invention will be described with reference to FIGS. In the three-dimensional sound field forming system of the present embodiment, two groups of ultrasonic speaker sets are arranged toward a space in which a sound field is to be formed (hereinafter, referred to as a target space). The first group of speaker sets consists of two ultrasonic speakers 11 and 12, and the second group of speaker sets also consists of two ultrasonic speakers 21 and 22. In addition, separately from them, the fifth ultrasonic speaker 31 is arranged facing the target space. Each speaker 11, 1
Ultrasonic amplification means 13, 14,
23, 24 and 33 are connected respectively.

Two ultrasonic speakers [1] of each group
[1, 12] and [21, 22] receive ultrasonic signals of the same frequency from the same ultrasonic signal generating means 15, 25. Assuming that the frequencies of the ultrasonic waves generated by the ultrasonic signal generating means 15 and 25 are f1 and f2, respectively, the two frequencies have a difference | f1
−f2 | is also set in the ultrasonic range (that is, 20 kHz or more).

Also, of the two ultrasonic speakers of each group, phase delay circuits 16 and 26 are provided between one of the speakers 12 and 22 and the ultrasonic signal generating means 15 and 25, respectively.

The fifth ultrasonic speaker 31 is connected to a means 35 for inputting a target audible sound signal via a frequency modulation means 37. Note that a storage unit for storing the audible sound signal may be provided before the audible sound input unit 35.

The operation of this system will be described specifically.
For example, the first group of ultrasonic signal generating means 15 generates ultrasonic waves having a frequency f1 = 40 kHz (wavelength λ1) shown in FIG. This ultrasonic signal is transmitted to the ultrasonic amplification unit 13.
Is sent to the first speaker 11 as it is. The ultrasonic wave of the same frequency f1 = 40 kHz (wavelength λ1) is transmitted to the second speaker 1
2, but the phase is delayed by θ1 (rad) by the phase delay circuit. As shown in FIG. 3, when these ultrasonic waves are emitted from the first and second speakers, the two ultrasonic waves interfere with each other, and their amplitudes only in the direction of the emission angle K1 calculated by the following equation based on the phase difference θ1. And cancel each other out. K1 = sin ^-1 ((c.theta.1) / (2.pi.L1.f1)) (where L1 is the distance between the speakers 11 and 12)

On the other hand, the ultrasonic signal generating means 25 of the second group generates ultrasonic waves having a frequency f2 = 60 kHz (wavelength λ2) shown in FIG. Difference from frequency f1 of first group |
f1−f2 | = f3 is 20 kHz. In the second group, the phase difference between the ultrasonic waves transmitted by the two speakers 21 and 22 is represented by θ2 (r
ad), a strong interference wave is emitted from the speaker set of the second group in the direction of the emission angle K2 according to the following equation. K2 = sin ^-1 ((c.theta.2) / (2.pi.L2.f2)) (where L2 is the distance between the speakers 21 and 22)

An area where these two interference waves intersect (hereinafter, referred to as
This is called an audible region. In the hatched portion in FIG. 1), sound waves from the speaker sets of both groups generate beats (interference), and form a sound wave (ultrasonic) field of | f1−f2 | = f3, which is the difference between the two frequencies. In this case, the frequency f1 of the ultrasonic wave from the speaker set of the first group is 40 kHz, and the frequency f2 of the ultrasonic wave from the speaker set of the second group is 40 kHz.
Since the frequency is 60 kHz, a sound field (ultrasonic field) of 20 kHz is formed in the audible region. In other target spaces, 40 kHz
And 60kHz ultrasound is prevalent.

As is clear from FIG. 3, the emission direction of the interference wave from the speaker set of each group may be not one but a plurality of directions. In the case of FIG. 3, interference occurs in two directions. However, by making the interval L1 between the speakers sufficiently shorter than the wavelength, the directions of the two interference waves are separated. Therefore, the interference wave from one group in FIG. 3 does not intersect with the interference wave from another group. Further, even if they are geometrically emitted in the intersecting directions, they intersect at a very distant place, so they are out of the room or the ultrasonic waves are attenuated, so that substantially no audible area is formed. However, of course, the reverse
By arranging L1 appropriately long, it is possible to positively use the audible area at a plurality of places at the same time.

Also, from the fifth ultrasonic speaker 31,
An ultrasonic wave having a frequency f3 (= | f1−f2 |) was used as a carrier wave and modulated with a target audible sound signal (the audible sound wave was superimposed).
Ultrasound is transmitted throughout the target space. Assuming that the frequency of the audible sound signal is f4, the frequency f5 of the ultrasonic wave transmitted from the fifth ultrasonic speaker 31 is f3 + f4. For example, if the frequency f4 of the audible sound wave is 1 kHz, the frequency f5 of the ultrasonic wave transmitted from the fifth ultrasonic speaker 31 is 21 kHz.

In the audible region, the ultrasonic wave (frequency f3) generated by the beat and the ultrasonic wave (frequency f5) from the fifth speaker 31 further generate a beat, and a sound wave having a difference between the two frequencies is generated. Here, the difference between the two ultrasonic waves is | f5−f3 | =
f4, which is exactly the frequency of the audible sound. That is, the target audible sound wave is demodulated in the audible region, and the audible sound can be heard only in the audible region.

An important point in the present system is that the position of the audible area can be freely moved in the target space without physically moving the speaker. That is, the phase delay circuit 1 provided in each of the first and second groups
6, 26, the phase difference θ1 and / or θ2 of each group
, The emission angle K1 and / or K2 of the interference wave from each speaker set can be arbitrarily changed by the above equation. Therefore, the audible area, which is the intersection area, can also be moved arbitrarily.

In the above example, even though the audible area can be freely moved, the moving range is two-dimensional.
The following method can be used to freely move the audible region three-dimensionally in the target space. As shown in FIG. 4, three (or more) ultrasonic speakers (1
1, 12, 17 and 21, 22, 27), and by providing a phase difference between the ultrasonic waves emitted from the three (or more) loudspeakers, the emission range of the interference wave falls within a predetermined solid angle range. It can be in the form of a beam. Therefore, an audible area can be formed at the intersection by directing the beam-like interference waves emitted from both speaker sets to a target area.

Another embodiment of the first aspect of the present invention will be described with reference to FIG. In this embodiment, one additional speaker (speaker 31 in the embodiment of FIG. 1) for transmitting audible sound superimposed ultrasonic waves is added to the embodiment shown in FIG. 1 (the added ultrasonic speaker is 41). . In the present embodiment, it is possible to demodulate two different types of audible sound waves in the audible region. The main use of this effect is stereo, but it is also conceivable that the main use and the sub-use are simultaneously supplied as in the case of TV multiplex broadcasting.

When the stereo effect is used, there are various methods for giving a listener a stereo feeling. One is a method of changing the volume of two kinds of sound waves. In the case of this embodiment,
For example, the volume of one audible-wave modulated ultrasonic speaker 31 is set higher than that of the other audible-wave modulated ultrasonic speaker 41. Accordingly, a person who listens in the audible region feels that sound is heard from a direction close to the audible wave modulated ultrasonic speaker 31 on the high volume side.

It is also possible to adopt a method of shifting the phases of both audible waves instead of the volume. Specifically, as shown in FIG. 6, the audible sound signal input means of one audible wave modulated ultrasonic speaker 41 is provided with a phase delay means 46. By making the phase of the audible wave signal of the audible wave modulated ultrasonic speaker 41 a little slower than that of the audible wave modulated ultrasonic speaker 31, a direction closer to the audible wave modulated ultrasonic speaker 31 to a person listening in the audible region. It feels like you can hear the sound.

FIGS. 7, 8, and 9 show examples of other system configurations (speaker arrangement examples) for obtaining a stereo effect or a surround effect.

Another embodiment of the first aspect of the present invention will be described with reference to FIG. In the present embodiment, a plurality of audible regions are formed in the target space. As described above, it is possible to form a plurality of audible regions even in the system of FIG.
However, these multiple locations cannot be independently located at any location. Therefore, in the system of the present embodiment, a plurality of ultrasonic waves for generating audible sound superimposed ultrasonic waves are transmitted. For example, from the ultrasonic speakers 51 and 52 of the first group, the frequency f21 = 60 kHz and the frequency f22 = 100 kHz
An ultrasonic wave on which ultrasonic waves of two frequencies are superimposed is transmitted. Then, from the ultrasonic speakers 61 and 62 of the second group, ultrasonic waves having waves of different phases superimposed at a frequency of f31 = 40 kHz are transmitted.

More specifically, an ultrasonic wave having a frequency f11 = 60 kHz (FIG. 11) is output from one of the speakers 51 of the first group.
(a)) and an ultrasonic wave (FIG. 12 (a)) in which an ultrasonic wave having a frequency f12 = 100 kHz (FIG. 11 (c)) is superimposed. From the other speaker 52, an ultrasonic wave having the same frequency f11 = 60 kHz and a phase shifted from the ultrasonic wave by θ11 (FIG. 11B), and a phase shifted by θ12 from the ultrasonic wave at the same frequency f12 = 100 kHz. The ultrasonic wave (FIG. 12) superimposed on the ultrasonic wave (FIG. 11 (d))
(b)). Due to the phase shifts θ11 and θ12,
Two emission angles K1 from the speaker set of the first group
1, beat (interference) ultrasonic waves can be transmitted to K12. K11 = sin ^-1 ((c ・ θ11) / (2 ・ π ・ L1 ・ f11)) K12 = sin ^-1 ((c ・ θ12) / (2 ・ π ・ L1 ・ f12))

Next, one of the speakers 61 of the second group
Then, an ultrasonic wave having a frequency of f21 = 40 kHz (FIG. 13A) is transmitted. The same frequency f21 = 40 kHz from the other speaker 62
The ultrasonic wave having a phase difference of θ21 with the ultrasonic wave (FIG. 13)
(b)) and an ultrasonic wave (FIG. 13 (d)) superimposed with an ultrasonic wave (FIG. 13 (c)) having a phase difference of θ22 is transmitted. Due to the phase shifts θ21 and θ22, beat (interference) ultrasonic waves can be transmitted from the speaker sets of the second group to the two emission angles K21 and K22. K21 = sin ^-1 ((c ・ θ21) / (2 ・ π ・ L1 ・ f21)) K22 = sin ^-1 ((c ・ θ22) / (2 ・ π ・ L1 ・ f21))

These four emission angles (K11, K12) × (K2
1, K22), four audible regions can be formed as shown in FIG. Of these four locations, two can be independently located at any location by appropriately setting θ11, θ12, θ21, and θ22, while the other two locations are formed at positions associated therewith.

In the above embodiment, the first group and the second group are used as a method for emitting an interference wave from each group in two directions.
Although different methods are used for the groups, it is of course possible to use the same method for both.

Each of the various systems described above includes means for forming a sound field in a specific area in the target space (aerial sound field forming means 8).
1), as shown in FIG. 14, by combining this with means for recognizing the position of the sound source of the audible sound reproduced in the sound field (sound source position recognition means 82), the sound field formation according to the present invention is achieved. The system opens up various practical applications. For example, as shown in FIG. 15, it is possible to configure a system that allows a person in a different room to have a conversation with a natural feeling as if they are sitting there. When the speaker moves in the room, the position of the speaker is recognized by the sound source position recognizing means, and the position of the audible area, which is the sound source reproduction area, is moved accordingly.

FIG. 16 shows a specific configuration of this system. As the sound source position recognizing means 82, two sound detecting means 83 and 84 are used. This is because the two-tone detection means 83
And the position of the sound source is recognized using the difference in the arrival time of the sound to the sound sources 84 and 84. For the recognition of the sound source position, various other methods conventionally used can be used. For example, when not only a speaker but also other unrelated people or sound sources are present in the room, only a specific person must be recognized as a speaker. In such a case, it is also effective to register the speaker's voice in advance and extract only the target voice by the speaker recognition method.

In addition to the system of FIG. 16, means for recognizing the position of the interlocutor who listens to the speaker's voice is added, and if the interlocutor moves, the position of the audible area which is the reproduced sound field is correspondingly moved. Can be moved.

FIG. 17 shows the first embodiment of the second aspect of the present invention.
This will be described below. First, an ultrasonic wave (synthetic ultrasonic wave) modulated by an audible sound to be transmitted to a user is emitted from a wide-area ultrasonic speaker 91 serving as a wide-area ultrasonic wave transmitting means toward a target space. As the ultrasonic speaker 91, an omnidirectional speaker is used when the area of the target space is to be widened, and a directional speaker is used when the target space is a relatively limited area. . Here, the frequency of the ultrasonic wave emitted from the ultrasonic speaker 91 is, for example, 20 kHz.
z.

The user carries a small portable ultrasonic speaker 92, which is a portable ultrasonic wave transmitting means, by hanging it on a neck or in a breast pocket. This portable ultrasonic speaker 92
The frequency of the ultrasonic wave emitted by the
(20 kHz in the above example)
The output is set so that the ultrasonic wave reaches a radius of about several tens of cm.

By adopting such a system configuration, the audible sound superimposed on the synthesized ultrasonic wave emitted from the wide-range ultrasonic speaker 91 is affected by interference only within a range of several tens cm around the portable ultrasonic speaker 92. The audio is reproduced and substantially transmitted only to the user holding it. Even if the user moves in the target space, sound is always transmitted as long as the user holds the portable ultrasonic speaker 92.

The ultrasonic speaker for wide area 91 need not always be fixedly installed at a specific place. It is of course possible to make it portable or mobile.

As shown in FIG. 18 (second embodiment), a plurality of directivity wide area ultrasonic speakers 911, 912, and 913 are provided, and different synthetic ultrasonic waves are emitted to different target spaces. It can also be kept. As a result, the user can hear different sounds (for example, descriptions of paintings) for each target space.

Next, an embodiment (third embodiment) of a method for restricting the existence area of the synthetic ultrasonic wave will be described with reference to FIG. Two ultrasonic speakers 91a and 91b are provided for the wide-area ultrasonic wave transmitting means.
By transmitting ultrasonic waves of the same frequency with different phases from both, a strong ultrasonic sound field is formed only in a specific direction as described with reference to FIG. This direction can be freely controlled by changing the phase difference between the ultrasonic speakers for wide area 91a and 91b. In the system of this embodiment, as in the case of the second embodiment, the wide-area ultrasonic speakers 91a and 91b
Audible sound is superimposed on the person.

FIG. 20 shows a configuration example (fourth embodiment) of a system for further restricting the existence range of the synthesized ultrasonic wave. In this system, the wide-area ultrasonic speakers 91c, 91d, 91
e and 91f are similar in structure and operation to the system of FIG. 5 or FIG. 6 and limit the reproduction range of the interfering ultrasonic wave in a similar manner, but in this system, the wide-range ultrasonic speakers 91c and 91d , 91e, 91f, a point where an audible sound to be transmitted is superimposed on the side of the ultrasonic wave emitted from the portable ultrasonic speaker, and a demodulating ultrasonic wave for extracting the audible sound is held by a user. It differs in that it is supplied from 92.

With these systems, it is possible to realize a use mode in which an audible sound can be heard only when the user enters a specific area.

In each embodiment of the second aspect, the ultrasonic speaker is held by the user on the moving side. However, the ultrasonic speaker may reproduce audible sound by electric means. I do not care. FIG. 21 shows a configuration example of such a portable audible sound reproducing unit 93. The audible sound reproducing unit 93 includes a microphone that collects the synthesized ultrasonic waves emitted from the wide-area ultrasonic wave transmitting unit 91, for example, a sound wave / electric signal converting unit that converts sound waves into electric signals by a piezoelectric bimorph ultrasonic sensor, and The amplification means is provided. Also provided are an electric oscillating means for generating an electric signal having the same frequency as the carrier of the synthetic ultrasonic wave, and means for amplifying the same. When these two signals are mixed by the mixing means, an audible sound frequency component, which is a difference component between the frequencies of the two electric signals, beats the electric signal (FIG. 22).
(a)). This is rectified by half-wave rectification means (FIG. 22 (b)), and high-frequency components are removed by a low-pass filter (FIG. 22 (c)). The audio signal of the audible sound frequency thus extracted is amplified by the amplifying means, and is provided as audible sound to a user holding the electric signal. This may be output by a small speaker or an earphone. Thus, in addition to the method of generating an acoustic beat (interference) and demodulating by the non-linear effect of air (parametric effect), an electrical beat (interference) is generated and only low frequency components are extracted and demodulated. There are also ways to do this.

An embodiment according to the third aspect of the present invention will be described with reference to FIG. The first transmission group is composed of two ultrasonic speakers 101 and 102 and two ultrasonic amplification units connected to each of the two speakers, similarly to the two transmission groups of the first aspect.
One ultrasonic signal generating means connected to both, and
It has a phase delay circuit connected to one ultrasonic speaker 102.

On the other hand, the audible sound superimposed ultrasonic wave transmission group
Two ultrasonic speakers 111 and 112, two ultrasonic amplification means connected to each of them, one frequency modulation means connected to both of them, an audible sound input means connected to the frequency modulation means, and one ultrasonic speaker It has a phase delay circuit leading to 112.

The operation of this system will be described specifically.
The ultrasonic wave having the frequency f6 (for example, 40 kHz) generated from the ultrasonic signal generating means of the first transmission group is transmitted to the first speaker 101 via the ultrasonic amplifying means 13 as it is. On the other hand, the ultrasonic wave having the same frequency f6 = 40 kHz is also transmitted to the second speaker 102, but in this case, the phase is delayed by θ4 (rad) by the phase delay circuit. As in the first embodiment of the first aspect, when these ultrasonic waves are emitted from the first and second speakers, they interfere with each other, and their phase difference θ4
Therefore, the amplitude increases only in the direction of the emission angle K3 calculated by the following equation, and cancels out in other directions. K3 = sin ^-1 ((c ・ θ4) / (2 ・ π ・ L3 ・ f6))

On the other hand, in the audible sound superimposed ultrasonic wave transmission group, the audible sound from the audible sound input means is transmitted to the ultrasonic wave having the frequency f6 (the same as the frequency of the ultrasonic wave in the first transmission group) by the frequency modulation means. Is superimposed on The ultrasonic wave on which the audible sound is superimposed is sent to the first speaker 111 as it is via the ultrasonic amplifier, and the ultrasonic wave whose phase is delayed by θ5 (rad) by the phase delay circuit is transmitted to the second speaker 112. Sent. As described above, a strong interference wave is emitted in the direction of the emission angle K4 from the speaker set of the audible sound superimposed ultrasonic wave transmission group by the following equation. K4 = sin ^-1 ((c ・ θ5) / (2 ・ π ・ L4 ・ f6))

In the region where these two interference waves intersect, the sound waves from the speaker sets of both groups generate localized interference waves, forming a sound field. In this case, the local interference wave formed from the carrier of the first transmission group (ultrasonic wave of frequency f6) and the carrier of the audible sound superimposed ultrasonic wave group (superimposition of audible sound on the ultrasonic wave of frequency f6) is , An audible wave corresponding to the difference between the two carrier waves. That is, unlike the case of the first aspect, the formed sound wave field itself becomes the target audible wave.

Also in the present system, by changing the phase difference θ4 and / or θ5 of each group, the position of the audible area can be freely moved in the target space without physically moving the speaker.

Further, by providing three (or more) ultrasonic speakers in each group and providing a phase difference to the ultrasonic waves emitted from the three (or more) speakers, the audible area can be three-dimensionally set in the target space. You can also move freely.

[0060]

The system according to the present invention for transmitting sound information only to a person who wants to convey the sound information is overflowing, and various application developments can be considered. For example, it can be applied to the description of an exhibit in an exhibition. In this case, the presence of a person in front of the exhibit is sensed, and only the person can hear the explanation. Similarly, in a large exhibition hall, the present invention can be used for a system for providing guidance at a branch point in a corridor. Alternatively, it can also be used as a three-dimensional sound field forming means of a virtual reality system. In addition, a wide range of applications can be considered for welfare purposes, such as a guide system for the visually impaired and a system for providing care for elderly people living alone by talking.

At present, the pedestrian ITS (Intelligent Transp.
A traffic safety system for protecting pedestrians called an ort system) has become an important issue. As an information providing service of the pedestrian ITS, for example, the following is required. 1) Providing location information: bus stop locations and bus schedules,
Guidance in public facilities (reception places, etc.), guidance in commercial facilities (entrances, sales floors, etc.), and notify the relevant parties of accidents during walking or wandering or getting lost of elderly people. Warning: Notification of steps, pedestrian crossings, construction points, steps at station platforms and public facilities, presence of obstacles 3) Route guidance: Appropriate route guidance to the destination, guidance on barrier-free routes with few obstacles, disaster Guides emergency evacuation routes at times 4) Providing various information ... Explanation of art objects and exhibits at museums

The three-dimensional sound field forming system according to the present invention can be suitably applied to these pedestrian ITS information providing services, and furthermore, these systems can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a three-dimensional sound field forming system according to a first embodiment of the first aspect of the present invention.

FIG. 2 is a waveform diagram of ultrasonic waves transmitted by each ultrasonic speaker of the system of the first embodiment.

FIG. 3 is an explanatory diagram of an interference sound field formed by two ultrasonic speakers.

FIG. 4 is a configuration diagram of an example of a system for restricting an audible area to a point-like area.

FIG. 5 is a configuration diagram of a system for supplying a plurality of audible sounds according to a second embodiment of the first aspect of the present invention.

FIG. 6 is a block diagram of another system for supplying a plurality of audible sounds.

FIG. 7 is a configuration diagram of a system for obtaining a stereo effect or a surround effect.

FIG. 8 is a configuration diagram of another system for obtaining a stereo effect or a surround effect.

FIG. 9 is a configuration diagram of still another system for obtaining a stereo effect or a surround effect.

FIG. 10 is a configuration diagram of a system for forming a plurality of audible regions according to a third embodiment of the first aspect of the present invention.

FIG. 11 is an original waveform diagram of an ultrasonic wave transmitted by each ultrasonic speaker of the system of the third embodiment.

FIG. 12 is a waveform diagram of an ultrasonic wave transmitted by each ultrasonic speaker of the system of the third embodiment.

FIG. 13 is an original waveform diagram and a transmission waveform diagram of an ultrasonic wave transmitted by each ultrasonic speaker of the system of the third embodiment.

FIG. 14 is a schematic configuration block diagram of a system in which a sound source position recognition unit is added to the system according to the present invention.

FIG. 15 is an explanatory diagram showing an equivalent concept of one application example of the sound field forming system according to the present invention.

FIG. 16 is a specific configuration diagram of a system to which a sound source position recognition unit is added.

FIG. 17 is a configuration diagram of a three-dimensional sound field forming system according to a first embodiment of the second aspect of the present invention.

FIG. 18 is a configuration diagram of a three-dimensional sound field forming system according to a second embodiment of the second aspect of the present invention.

FIG. 19 is a configuration diagram of a three-dimensional sound field forming system according to a third embodiment of the second aspect of the present invention.

FIG. 20 is a configuration diagram of a three-dimensional sound field forming system according to a fourth embodiment of the second aspect of the present invention.

FIG. 21 is a block diagram showing a configuration example of portable audible sound reproducing means for electrically reproducing audible sound in the three-dimensional sound field forming system according to the second embodiment of the present invention.

FIG. 22 is a waveform chart showing a state of demodulation of an electric signal in the above example.

FIG. 23 is a configuration diagram of a three-dimensional sound field forming system that is an example of the third embodiment of the present invention.

Claims (11)

[Claims] 1. An eleventh ultrasonic wave transmitting means for transmitting an ultrasonic wave having a frequency f1, and an ultrasonic wave having a phase shifted by θ1 from the ultrasonic wave emitted from the eleventh ultrasonic wave transmitting means at a frequency f1. A first transmission group comprising twelfth ultrasonic transmission means for transmitting, and b) a twenty-first ultrasonic transmission means for transmitting an ultrasonic wave having a frequency f2 whose difference from the frequency f1 is in an ultrasonic range. A second transmission group including: a second transmission unit that transmits an ultrasonic wave having a frequency f2 and a phase shifted by θ2 from the ultrasonic wave generated by the twenty-first ultrasonic transmission unit; c) | An audible sound superimposed ultrasonic wave transmitting means for transmitting an ultrasonic wave having a frequency difference of an audible sound wave with respect to an ultrasonic wave having a frequency of f1−f2 |. 2. The three-dimensional sound field forming system according to claim 1, further comprising means for changing the phase difference θ1 and / or θ2. 3. The first transmitting group includes a seventeenth ultrasonic transmitting unit that transmits an ultrasonic wave having a phase shifted by θ12 from the ultrasonic wave generated by the eleventh ultrasonic transmitting unit, and a second transmitting group. To
The three-dimensional ultrasonic wave transmitting means according to claim 1 or 2, further comprising a twenty-seventh ultrasonic wave transmitting means for transmitting an ultrasonic wave having a phase shifted by θ22 from the ultrasonic wave emitted from the twenty-first ultrasonic wave transmitting means. Sound field formation system. 4. A second audible sound superimposed ultrasonic wave transmitting means for transmitting an ultrasonic wave having a frequency difference of another audible sound wave to an ultrasonic wave having a frequency of | f1-f2 | The three-dimensional sound field forming system according to claim 1, wherein: 5. A third audible sound superimposed ultrasonic transmission for transmitting an ultrasonic wave having a frequency difference of an audible sound wave having a phase difference with respect to an ultrasonic wave having a frequency of | f1−f2 | The three-dimensional sound field forming system according to any one of claims 1 to 3, further comprising a wave means. 6. The three-dimensional sound field forming system according to claim 1, wherein ultrasonic waves in which ultrasonic waves of different frequencies are superimposed are transmitted from each transmission group. 7. A wide-area ultrasonic wave transmitting means for emitting a synthesized ultrasonic wave in which an audible sound is superimposed on a carrier ultrasonic wave to a wide area, and b) a portable phone for emitting an ultrasonic wave having the same frequency as the carrier ultrasonic wave to a narrow area. Type ultrasonic wave transmitting means, and reproduces an audible sound by interference between both ultrasonic waves only in the vicinity of the user by moving in a wide area while holding the portable ultrasonic wave transmitting means. A three-dimensional sound field forming system, characterized in that: 8. The 31st ultrasonic wave transmitting means for transmitting ultrasonic waves of frequency f3, said wide-area ultrasonic wave transmitting means,
And the phase of the ultrasonic wave emitted from the 31st ultrasonic wave transmitting means is θ3.
8. The three-dimensional sound field forming system according to claim 7, further comprising a 32nd ultrasonic wave transmitting means for transmitting ultrasonic waves shifted by only a distance. 9. A) No. 101 transmitting an ultrasonic wave having a frequency f6
A first transmission group including an ultrasonic transmission unit and a 102nd ultrasonic transmission unit that transmits an ultrasonic wave having a frequency f6 and a phase shifted by θ4 from the ultrasonic wave generated by the 101st ultrasonic transmission unit; B) an 111th ultrasonic transmitting means for transmitting an ultrasonic wave obtained by superimposing an audible sound on the ultrasonic wave of the frequency f6, and an ultrasonic wave having a phase shifted by θ5 from the ultrasonic wave emitted by the 111th ultrasonic transmitting means. A three-dimensional sound field forming system, comprising: an audible sound superimposed ultrasonic wave transmitting group comprising: a 112th ultrasonic wave transmitting means for transmitting a sound wave. 10. The three-dimensional sound field forming system according to claim 9, further comprising means for changing the phase difference θ4 and / or θ5. 11. An audible sound superimposed ultrasonic wave, wherein a 107th ultrasonic wave transmitting means for transmitting an ultrasonic wave having a phase shifted by θ42 from the ultrasonic wave emitted from the 101st ultrasonic wave transmitting means to the first transmitting group. No. 117 transmitting an ultrasonic wave whose phase is shifted by θ52 from an ultrasonic wave emitted from the 111st ultrasonic wave transmitting means to the transmission group.
11. The three-dimensional sound field forming system according to claim 9, wherein ultrasonic wave transmitting means are provided.