JP2001069591A - Directional loudspeaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a directional loudspeaker with a simple configuration, where sound is hardly heard or a sound of other contents is heard depending on an area over a wide range of sounds. SOLUTION: In this directional loudspeaker, a midrange loudspeaker and a woofer 5a, 5b are placed side by side at an interval of 1/8 to one wavelength of emitted sound wave and emit a sound wave which includes medium and low sound frequency components of 1st channel and 2nd channel acoustic signals A, B. A sound source controller SC including an acoustic signal control circuit 2 is inserted between both acoustic signal sources (A, B) and both the loudspeaker 5a, 5b, so as to cancel each channel component emitted from both the loudspeakers by the interference of the sound waves in different areas in an acoustic space. Directional array tweeters 9a, 9b emit high sound frequency components of the 1st and 2nd channel acoustic signals A, B via high-pass filters 6a, 6b, power amplifiers 7a, 7b and distribution circuits 8a, 8b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional loudspeaker capable of listening to sounds of different signal sources in different regions with respect to a pair of speakers, more specifically, a signal source in a predetermined listening area. Making it difficult to hear the sound of
The present invention relates to a directional loudspeaker capable of transmitting different sound information to a plurality of listening areas so that different sounds can be heard in different listening areas.

[0002]

2. Description of the Related Art Conventionally, as a device for simultaneously listening different sounds in different regions of the same space, the directivity of sound radiated from a speaker is controlled in two or more desired directions. There was something. For example, Japanese Unexamined Patent Publication
Japanese Patent Publication No. 205496 (“speaker device”) discloses FIG.
As shown in (1), each input signal (IN1, IN2) supplied to an array speaker (AS) in which a plurality of speakers are linearly arranged is converted into a digital filter (DF1 to DF1).
m), digital signal processing for making the delay time and the like different is individually performed, whereby the array speaker (A
S), the directivity (D1, D1) of each input signal sound emitted from
Although a technique for controlling 2) is described, this technique has a disadvantage that the device becomes large-scale.

In general, an array speaker physically arranged in an array provides acoustic signal power in the same phase,
Due to the sound wave interference, the sound pressure other than at the front becomes very low, and the directivity becomes very sharp. However, in order to obtain sufficiently sharp directivity, the longitudinal direction (array direction) of the array speaker
Dimensions require several wavelengths of sound waves. For this reason, in the low-middle tone range, it is difficult to keep it within practical dimensions. For example, one wavelength of a sound wave having a frequency of 1 kHz is 34c
m, a large size of 1 m to several m is required to obtain sufficient directivity at frequencies lower than this.

Japanese Patent Laid-Open No. Hei 5-344579 ("Speaker system and a television receiver using the speaker system") discloses, as shown in FIG.
An acoustic partition (P) is provided on an acoustic tube (ST) for guiding sound waves radiated from the speaker diaphragms of the two speaker units (SU).
P) and a sound-absorbing panel (AP) are provided to give the speaker directivity in an arbitrary direction structurally. However, in this technology, the suppression ratio effect is small and the directivity direction can be switched. It has the disadvantage of not being easy.

On the other hand, the present inventors cancel digital sound processing of predetermined sound wave components radiated from two speakers arranged in close proximity to each other, thereby enabling two persons (or 2 persons) in different areas of the same space. Groups)
Japanese Patent Application No. 10-39378 (hereinafter referred to as "the proposal") proposes a speaker device which enables a listener to listen to the sounds of different sound sources at the same time. There is a drawback that the frequency band is narrow, and in particular, the controllable region of the high frequency range is narrowed.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention makes it difficult to hear the radiated sound from a speaker in a space where the radiated sound from a pair of left and right speaker systems is listened, particularly in a certain area. Or, in different areas, the sounds of different sound sources can be heard simultaneously, and the areas that are difficult to hear or the areas that can be heard individually are expanded regardless of the frequency band, and An object of the present invention is to provide an improved directional loudspeaker in which the controllable area of the loudspeaker can be further improved, and the structure can be simplified and the size can be reduced.

[0007]

According to the present invention, two middle and low-frequency speakers (5a, 5b) juxtaposed at an interval of 1/8 to 1 wavelength of a sound wave in a control frequency band, and an acoustic signal source (C) a middle / low sound canceling control means (SC) interposed between (A, B) and the middle / low sound speaker to cancel sound waves radiated from the middle / low sound speaker in the listening space by interference between sound waves. And a directional loudspeaker (9a, 9b) for emitting a sound based on a high-range sound signal from the sound signal source, or one-eighth of a sound wave in a control frequency band. Two low-mid speakers (5a, 5b) juxtaposed at an interval of one wavelength to one wavelength
And between the two acoustic signal sources (A, B) and the speaker for middle and low-frequency sounds to cancel sound waves radiated from the speaker for middle and low-frequency sounds in different regions in the listening space by interference between the sound waves. Medium bass cancellation control means (SC)
And a directional loudspeaker (9a, 9b) for emitting a sound based on a high-range sound signal from the sound signal source.

According to another feature of the present invention, the directional treble speaker can be constituted by an array loudspeaker (SA, SB), and according to another feature, a middle / low sound loudspeaker and a directional treble speaker can be constituted. Speaker for array speaker (S
A, SB). Furthermore,
In the latter case, the middle / low-range speaker is divided into a middle-range speaker unit (SM) and a low-range speaker unit (SL), and the middle-range speaker unit (SM) is located at the center of the array speakers (SA, SB). And a bass speaker (S
L) can be located.

[Operation] According to a first feature of the present invention,
Two loudspeakers (5a, 5b) are arranged close to each other at an interval of 1/8 wavelength to 1 wavelength of the sound wave in the frequency region to be controlled, and a sound wave of a middle / low range sound signal in this frequency region is emitted. Intermediate / low-pitched sound canceling control means (SC) is interposed between the acoustic signal source (for example, A) and one of the speakers (5b). The sound waves in the low-middle range radiated from the speaker are canceled out by the interference between the sound waves. For the treble sound signal of the sound signal source, the corresponding treble sound wave is
Sound is emitted from a directional treble speaker (for example, 9a) in a direction avoiding the cancellation region. Therefore, using a small-sized speaker device, in the above-mentioned cancellation area and the listening area in the vicinity thereof, both the sound in the middle and low range and the sound in the high range are both
It can make it difficult to hear enough.

According to a second feature of the present invention, two loudspeakers (5a, 5b) are arranged close to each other via an interval of 1/8 wavelength to 1 wavelength of a sound wave in a controlled frequency range, and the control frequency range is controlled. And each has a different content type (that is,
Sound waves in the low-middle range including the first and second channel sound signal components (without correlation) are emitted from both speakers. Intermediate / low-frequency sound canceling control means (SC) is interposed between the second channel and first channel sound signal sources (B, A) and the first and second speakers. In different first or second regions of
In each case, the second channel or first channel acoustic signal component of the sound wave in the middle and low range radiated from each speaker is canceled by the interference between sound waves. Regarding the high-range sound signal of the first channel or second-channel sound signal source (A, B), the corresponding high-range sound wave is transmitted from the directional high-range speakers (9a, 9b) to the medium-low range sound wave, respectively. Sound is emitted in a direction toward the region where the second channel or first channel acoustic signal component is canceled. Therefore, using a small-sized speaker device, separate sounds from the first channel or the second channel sound signal source (A, B) are sent to each of the cancellation areas and each of the listening areas in the vicinity thereof by using the middle / low range. Both the high-pitched sound and the high-pitched sound can be heard effectively.

According to the present invention, as described above, the middle and low range is controlled by the middle and low range canceling control means (SC).
The sounds emitted from the two speakers (5a, 5b) are mutually canceled using the interference of sound waves, and the sound in only a specific direction toward the listening area using the directional treble speakers (9a, 9b) in the treble range. By increasing the pressure level, it is possible to effectively transmit different sound information to a plurality of listening areas including a high-frequency range. According to another feature of the present invention, the directional treble speaker (9a, 9
By using a highly directional sound source such as an array speaker in b), effective transmission of separate sound information to each listening area including a high sound range can be realized with a simple configuration.

Further, according to another feature of the present invention, a speaker for middle and low-pitched sound is also included in the array speakers (SA, SB), and a part or the whole of the array speaker is cancelled by middle-low-pitched sound canceling means (SC). The speaker structure can be further simplified by using the speaker as a medium / low-frequency speaker driven through the speaker. In this case, the speaker for the middle and low frequency is replaced by the speaker for the medium tone (SM) and the speaker for the low tone (SL)
The middle speaker unit (SM) is located at the center of the array speaker (SA, SB), and the bass speaker unit (SL) is located outside of the middle speaker unit (SM). Method can be adopted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. The following embodiment is merely an example, and various modifications can be made without departing from the spirit of the present invention.

[System Configuration] FIG. 2 is a block diagram showing the configuration of a directional loudspeaker according to an embodiment of the present invention. In this example, the first and second channel audio signals A and B having different content types (that is, no correlation) are input to the directional speaker.
These two audio signals A and B are converted into digital signals by analog-to-digital conversion circuits (ADCs) 1a and 1b, and then supplied to the audio signal control circuit 2.

The audio signal control circuit 2 includes first and second delay units 21 and 22 and first and second digital filters 2.
A first channel sound signal A is supplied to the first delay unit 21 and the first digital filter 23;
The second channel sound signal B is supplied to the second delay unit 22 and the second digital filter 24. Output signals of the first delay unit 21 and the second digital filter 24 in the audio signal control circuit 2 are respectively passed through digital-to-analog conversion circuits (DACs) 31 and 34 and first and second attenuators AT. The output signals of the second delay unit 22 and the first digital filter 23 in the acoustic signal control circuit 2 are added to the DACs 32 and 3 respectively.
The signals are added by the second adder circuit AD via the third and third and fourth attenuators AT.

The added output signal of each adder circuit AD is amplified by the first and second power amplifiers 4a and 4b, respectively, and then input to the first and second middle bass speakers 5a and 5b. The two middle bass speakers 5a and 5b are arranged at an interval (d0) of 1/8 wavelength to 1 wavelength of the sound wave in the main control frequency region of the first and second channel acoustic signals A and B, respectively. , First and second power amplifier 4
a, and emits a sound wave based on the signal input from 4b.

The ADCs 1a and 1b, the acoustic signal control circuit 2, the DACs 31 to 34, the attenuator AT, the adder circuit AD, and the first and second power amplifiers 4a and 4b are, as shown in FIG. The apparatus SC is configured, and the first and second middle and low-frequency speakers 5a and 5b are driven by the sound source control apparatus SC to provide a proximity sound source control (PSC: Proximate Sourse Control) method [hereinafter, the "PSC method". Simplified representation. ] Is realized. When the speakers 5a and 5b are driven by the PSC method, two different points Pa and Pb in the listening space (not shown. For example, in FIG. 2, the first and second middle and low speakers 5a and 5b are placed in a back position). ,
Left front and right front, respectively. ), Only the first channel or second channel audio signal component (A, B) is heard, respectively, and the second channel or first channel audio signal B,
A can be prevented from hearing the crosstalk sound derived from A. Such a proximity control sound source has already been described in the above proposal, but its principle will be described later.

In one embodiment of the present invention, as shown in FIG. 2, first and second channel audio signals A and B are provided.
Of the middle and low range of about 100 Hz to 2500 Hz (or 3000 Hz) of the first and second middle and low range speakers 5a and 5b by the sound source control device SC using the PSC method.
, And 3 kHz (or 2.5 kHz) to 1 kHz of the first and second channel acoustic signals A and B.
For high-tone sounds of about 5 kHz, high-pass filters 6a and 6b, power amplifiers 7a and 7b, distribution circuits 8a and 8b, and high-directivity high-tone speakers 9a and 9b, respectively.
b is provided to obtain a desired directivity for sounds in a high-frequency range. That is, the first channel and second channel audio signals A and B are respectively converted to the high-pass filters 6a and 6a.
b, the treble signals of the first channel and the second channel obtained through the first and second channels are amplified by the power amplifiers 7a and 7b and subjected to a predetermined signal intensity gradient by the distribution circuits 8a and 8b. , 9b.

Here, directional treble speakers 9a, 9b
As shown in FIG. 2, 3 kHz (or 2.5 kHz
z) It is preferable to use an array speaker having a narrow (high) directivity in a band of １５15 kHz. However,
A speaker having the same directivity (for example, a structure having the same directivity as shown in FIG. 1A, if possible) may be used. FIG. 3 is a diagram showing an appearance of a directional loudspeaker according to one embodiment of the present invention. The speakers 5a and 5b are driven by the PSC system so that only the first channel or second channel sound signal components (A and B) can be heard at the listening points Pa and Pb, respectively. In this case, each of the treble array speakers 9a and 9b tilts the physical arrangement direction as shown in FIG. 2 and FIG. 3 and adjusts the intensity gradient of the signal supplied to the sounding unit. Listening points Pa, P
A predetermined directional characteristic is given in the direction toward b.

[Principle of the PSC system] Now, in the acoustic listening space for both middle and low-frequency speakers 5a and 5b, a certain point Pa (not shown; for example, in FIG. Considering this point Pa
Are heard by the first and second middle bass speakers 5
The sound pressures of the sounds emitted from a and 5b are linearly superposed. Accordingly, the sound pressure S (ω) at the listening point Pa is obtained by converting the voltage of the first channel sound signal A by X
(Ω), if the voltage of the second channel acoustic signal B is Y (ω) (ω is the angular frequency of the sound signal), it can be expressed by the following equation (1): S = (αX + βY) + (γX + δY) (1) where α is the circuit element 1a → 21 → 31 → 4a → 5a
And elements 1a to 5a to Pa having a path from space 5a to Pa
The transfer function β between the circuit elements 1b → 24 → 34 → 4a
→ 5a and space 5a → Elements 1b to 5a with a path of Pa
, The transfer function between Ｐａ and Pa is the circuit element 1a → 23 → 33
→ 4b → 5b and space 5b → 1a to 5 with the path of Pa
The transfer function δ between b and Pa is represented by the circuit element 1b → 22 → 32
→ 4b → 5b and space 5b → 1b to 5 with Pa as a route
This is a transfer function between b and Pa.

That is, the first term on the right side represents the sound radiated from the first speaker 5a and heard at the listening point Pa, and the second term on the right side is emitted from the second speaker 5b. The sound heard at the listening point Pa is shown. Therefore, when the digital coefficient of the second digital filter 24 is adjusted to change the coefficient β to satisfy β = −δ, the equation (2) is obtained from the equation (1) and includes the second channel acoustic signal voltage Y. Terms can be deleted. S = αX + γX = (α + γ) X (2)

This means that at the listening point Pa, the first
Only the sound derived from the channel sound signal A (signal voltage X) is heard, and the second channel sound signal B (signal voltage Y)
Indicates that the crosstalk sound [(β + δ) Y] derived from the sound cannot be heard.

The same operation is performed by another point Pb (not shown in FIG. 2) symmetrical with respect to the center line between the middle and low bass speakers 5a and 5b at the listening point Pa. For example, in FIG. 5b as the back and right front.), The filter of the first digital filter 23 is also adjusted to α = −γ, so that the second channel acoustic signal B (signal voltage Y ) Can be heard, and the crosstalk sound [(α + γ) X] derived from the first channel acoustic signal A (signal voltage X) cannot be heard.

With such a configuration, each digital filter 2
According to 3, 24, only one point in the listening space can satisfy β = −δ or α = −γ, and at that point (hereinafter referred to as “cancellation point”), the crosstalk is zero. Become. In addition, an area with a small amount of crosstalk is generated around the cancellation point.

For example, if the crosstalk at the listening point Pa is made zero by adjusting the filter coefficient of the second digital filter 24 to satisfy β = −δ, the crosstalk in the area near the listening point Pa is reduced. Reduced
When the crosstalk at the listening point Pb is set to zero by adjusting the filter coefficient of the first digital filter 23, the crosstalk is reduced in a symmetrical area near the listening point Pb. This, as explained below,
The present invention has been elucidated by the present inventors, and the invention utilizing this phenomenon is described in detail in the above proposal.

In general, when speakers are sufficiently separated from each other in a diffuse sound field, crosstalk is -10 dB.
It is said that such a space is substantially circular and has a size of about one tenth of the wavelength of the sound wave in the control band (for example, “A. David and SJ Elliot 1993 applied
acoustics 41, 63-79. Numerical studies of activel
y generated quiete zones ”). Conversely,
1/8 of the wavelength of the sound wave at the control frequency
It is known that when approaching the following, the area where the crosstalk becomes -10 dB or less spreads out in front of both the two speakers, and in the case of a two-channel configuration, the areas where the crosstalk is reduced overlap.

As shown in FIG. 2, the speakers 5a and 5b for middle and low frequency sounds
In a system with juxtaposed
Then, the crosstalk reduction region where the crosstalk becomes −10 dB when the speaker spacing is changed changes as a function of the speaker spacing for a predetermined wavelength λ.
When the loudspeakers 5a and 5b are sufficiently separated from each other so as to satisfy the relationship of "speaker distance d1> wavelength λ", crosstalk is reduced in a substantially circular small area [see FIG. 2A of the above proposal. ]. In addition, when the two speakers 5a and 5b are brought closer to each other so as to satisfy the relationship of “speaker distance d2> (1/8) × wavelength λ”, the crosstalk reduction region is greatly expanded, but the first channel and the second channel are reduced. The crosstalk reduction regions for the audio signal components overlap each other [see the proposed FIG. 2 (C). ].

However, when the speaker interval d0 is (1/8) × λ <d0 <λ (3) as in the present invention, the crosstalk reduction regions of the respective audio signal components are independent. This also results in a large volume [see FIG. ]. In FIG. 2, the sound field according to the PSC method is the first sound field by the sound source control device SC.
And the second middle and low range speakers 5a and 5b (for example, the distance d0 between the centers of the middle and low range speakers 5a and 5b is approximately 40
cm or less. ) Is realized by the proximity control sound source that drives

[Outline of formation of sound field in middle and low range and high range]
According to such a PSC system, 100 Hz to 2500
With respect to the sound in the middle and low frequency range of about Hz (or 3000 Hz), the sound pressure in a specific direction can be lowered, and the region where the crosstalk can be reduced favorably can be made independent. For a sound in a high frequency range of about 3000 Hz or more, the controllable crosstalk reduction region is narrow, and it is difficult to achieve a desired effect.

Therefore, in one embodiment of the present invention, FIG.
As shown in FIG. 3, the sound source control device SC for the middle and low range sounds of the first and second channel sound signals A and B is provided.
1st and 2nd low mid speaker 5
a and 5b, and high-pass filters 6a and 6b and power amplifiers 7a and 7b for high-frequency sounds of the first and second channel acoustic signals A and B, respectively.
b, distribution circuits 8a and 8b and high-directivity high-tone speakers 9a and 9b are provided.

FIGS. 4 and 5 show the PSC according to the present invention.
FIG. 6 is a diagram for explaining formation of a middle and low range sound field by the middle and low range speakers 5a and 5b, and FIG. 6 illustrates formation of a high range sound field by the directional high range speakers 9a and 9b in the present invention. FIG. For example, it is assumed that a broadcast sound signal of “English” is input to the sound source control device SC as the first channel sound signal A, and a broadcast sound signal of “Spanish” is input as the second channel sound signal B.

In the present invention, for example, 100 Hz
For the sound in the low-middle range of up to 2500 Hz (or 3000 Hz), a pair of two low-middle speakers 5
The PSC method is applied to a and 5b to create a direction (DA) where sound of one channel is hard to hear, and similarly, a direction (DB) where sound of the other channel is hard to hear. For example, regarding “Spanish” of the second channel sound signal B, the direction that is hard to hear is “D” in FIG.
A sound field having a direction indicated by “A” is generated, and for “English” of the first channel sound signal A, a sound field in which the hard-to-hear direction is the direction indicated by “DB” in FIG. 4B is generated. Thus, the proximity control sound source including the sound source control device SC is set. When the sound signals A and B of these two channels are superimposed and reproduced by the proximity control sound source,
As shown in FIG. 5, there are two directions DA and DB in which only “English” or “Spanish” is easy to listen to, so that bilingual Spanish and English broadcasts can be sorted into the two directions DA and DB.

In one embodiment of the present invention, for example,
For sounds in the high frequency range of 2500 Hz (or 3000 Hz) or higher, array speakers 9a and 9b physically arranged in an array are used. The array speakers 9a and 9b are sound sources with extremely sharp directivity, and have a characteristic that when power is applied to the same phase, the sound pressure other than at the front becomes very low due to sound wave interference. Therefore, each array speaker 9a, 9b
As shown in FIG. 6, the directivity of the first channel is adjusted to the directions DA and DB of FIG.
The "Spanish" of the channel can be heard only in the listening areas of the desired directions DA and DB, respectively, even in the treble range. Therefore, according to the present invention, bilingual broadcasts can be effectively distributed to the two directions DA and DB for the entire sound range.

In order to obtain a sufficiently sharp directivity with an array speaker, a longitudinal dimension for several wavelengths of a sound wave is required.
It is difficult to keep the middle and low range within practical dimensions. However, in the present invention, as described above, the PSC method is applied to the middle and low range sound, and the high range sound is driven by the in-phase drive of the array speaker. Is applied, the size of the speaker mechanism can be reduced.

[Other Configuration Examples] In the present invention, not only the directional treble speakers 9a and 9b but also the middle and low-tone speakers 5a and 5b can be constituted by array speakers. FIG. 7 is a block diagram showing the configuration of a directional loudspeaker according to another embodiment of the present invention. The same reference numerals as those in FIG. 2 indicate the same components as those in FIG. In this embodiment, the functions of the middle and low-frequency speakers 5a and 5b and the directional high-frequency speakers 9a and 9b in FIG. 2 are realized by the array speakers SA and SB, thereby further simplifying the configuration of the speaker device. Can be. FIG. 8 is a diagram showing an appearance of a directional loudspeaker according to another embodiment of the present invention.

In the example shown in FIGS. 7 and 8, the array speakers SA and SB are driven in-phase by the distribution circuits 8a and 8b, respectively, with a predetermined intensity gradient by high-range sound signals of the first and second channels. Instead, some of the sounding units on the center side (in the case shown, the inner three units)
The outputs of the power amplifiers 4a and 4b are supplied via the adder circuit AD, and the output is driven by the PSC method. When used in combination with an array speaker as a PSC drive speaker, the center-side sounding unit driven by the PSC method is the eighth sound wave of the control frequency band of the middle and low frequency components of the first and second channel sound signals A and B. It is necessary to satisfy the interval of one wavelength to one wavelength, and depending on the condition, as shown in a development view of both speaker output surfaces in FIG. May be unused.

FIG. 9 (2) shows an example of another loudspeaker configuration when part or all of an array loudspeaker used as a directional treble loudspeaker is commonly used as a PSC type loudspeaker for a low-mid range. Also in the array speakers SA and SB shown in FIG. 9 (2), all the sounding units are driven in-phase with a predetermined intensity gradient by a high-range sound signal, and some sounding units near the center employ the PSC method. The function of a speaker for low and mid frequencies is provided.

As described above, both array speakers SA, SB
Is driven in-phase not only by the first channel and the second channel high-range sound signal, but also by PSC driving by the middle-low range sound signal, basically, the PSC middle-range sound signal drives the inner unit of the array speaker. Used, whereas the PSC bass sound signal uses the outer unit of the array speaker. In the example of FIG. 9 (2), the function of the speaker for middle / low frequency is divided into the speaker section SM for middle frequency and the speaker section SL for low frequency, and the middle speaker section SM is located on the center side of the array speaker. The bass speaker SL is located outside the speaker. In this case, for example, the sound source control device SC
Of the power amplifiers 4a and 4b can be supplied through an appropriate filter.

It should be noted that the function of the speaker for the middle and low range for the PSC system middle and low range sound signal can be divided not only into the above-mentioned two ranges but also into many ranges. Further, it is not necessary to use all the sounding units for the high-range sound signal, and some
It may be driven only by the system or not used.

[Other Embodiments] In the PSC system, the sound wave canceling area (position and direction) is controlled, for example, by using the filter coefficient control already proposed by the present inventors (Japanese Patent Application No. 11-101805, 102110). However, such filter coefficient control is adopted in the sound source control device of the present invention, and the arrangement and directional characteristics of high directivity speakers such as array speakers are changed accordingly. Can be configured.

Further, the directional sound loudspeaker according to the present invention comprises:
For example, it is possible to intentionally create an area in the same room where the volume of a television broadcast or a radio broadcast is lower than the surroundings in an arbitrary direction or position. It can be used as a speaker of a receiver for television audio multiplex broadcasting, and it is possible to enjoy the main and sub-channels of audio multiplex broadcasting such as bilingual broadcasting with two persons (or two groups) simultaneously with separate sounds. A region can be intentionally created in any direction or position. In addition, the present invention is not limited to broadcasting such as television and radio, and is used in various directional loudspeaker systems where a small volume is created in a certain area or a different broadcasting is performed in two areas indoors or the like. be able to.

[Effects of the Invention] As described above, according to the present invention, one-eighth of the sound wave in the frequency region to be controlled is provided.
The two speakers (5a, 5a)
b) is arranged in close proximity to radiate the sound wave of the middle and low range sound signal in this frequency range, and the middle and low range canceling control means is interposed between the sound signal source and one of the speakers, whereby In a certain region of the listening space, sound waves in the middle and low frequency range radiated from both speakers are canceled by interference between sound waves, and a high-range sound signal of an acoustic signal source is canceled out by a directional treble speaker. Since the sound was emitted in a direction avoiding the area, using the small-sized speaker device, in the above-described canceling area and the listening area in the vicinity thereof, both the sound in the low-middle range and the sound in the high-range range were sufficient. You can make it difficult to hear.

Further, according to the present invention, the sound waves in the controlled frequency range are separated from each other by an interval of 1/8 wavelength to 1 wavelength.
Two speakers are arranged in close proximity to each other, and sound waves in the low-middle range including the first and second channel sound signal components having different (uncorrelated) content types in the frequency range are radiated from the two speakers, respectively. Between the channel and the first channel acoustic signal source and the first and second speakers;
By inserting the middle / low-tone canceling control means, the second channel or the first channel of the middle / low-range sound wave radiated from each speaker in the different first or second regions in the listening space of both speakers, respectively. The acoustic signal component is canceled by interference between sound waves, and the high-range sound signal of the first channel or the second channel sound signal source is transmitted from the directional treble speaker to the second or first channel of the medium-low range sound wave, respectively. Since the sound is emitted in the direction toward the area where the channel acoustic signal component is canceled, the first channel or the second channel is used in each canceling area and each listening area in the vicinity thereof using a small-sized speaker device. With respect to the different sounds from the acoustic signal source, the sound in the middle and low range and the sound in the high range can be effectively heard.

According to the present invention, for the low midrange sound, the sounds emitted from the two speakers are mutually canceled out using the interference of the sound waves by using the low midrange sound canceling control means. By increasing the sound pressure level only in a specific direction toward the listening area using the speaker, it is possible to effectively transmit different sound information to a plurality of listening areas including the high-frequency range. In addition, the directional treble speaker uses a highly directional sound source such as an array loudspeaker so that the effective transmission of separate sound information to each listening area including the treble range can be further simplified. Can be realized.

Further, according to the present invention, the speaker for middle / low-pitched sound is also included in the array speaker, and part or all of the array speaker is used as a speaker for middle / low-pitched sound driven through the middle / low-pitched sound canceling control means. By using it, the speaker structure can be further simplified. In this case, the listening environment is such that the middle / low-range speaker is divided into a middle-range speaker and a low-range speaker, and the middle-range speaker is positioned at the center of the array speaker and the low-range speaker is positioned outside the array speaker. , Various effective methods can be adopted.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a conventional technique regarding a directional loudspeaker;

FIG. 2 is a block diagram showing a system configuration of a directional loudspeaker according to one embodiment of the present invention.

FIG. 3 is an external view of a directional loudspeaker according to an embodiment of the present invention.

FIG. 4 is a part of a diagram for explaining a sound field formation by a proximity control sound source according to the present invention.

FIG. 5 is another part of the diagram for explaining the sound field formation by the proximity control sound source in the present invention.

FIG. 6 is a diagram for explaining a sound field formation by a directional sound source according to the present invention.

FIG. 7 is a block diagram showing a system configuration of a directional loudspeaker according to another embodiment of the present invention.

FIG. 8 is an external view of a directional loudspeaker according to another embodiment of the present invention.

FIG. 9 is a diagram showing another example of an array speaker array according to another embodiment of the present invention.

[Explanation of symbols]

 2 Acoustic signal control circuit, 5a, 5b Loudspeaker, 9a, 9b Loudspeaker, ADC analog / digital converter, AT attenuator, AD addition (mixing) circuit, DAC digital / analog converter, SC sound source controller, SA , SB Array speaker. SM Medium tone speaker, SL Low tone speaker.

Claims (5)

[Claims] 1. An eighth to one wavelength of a sound wave in a control frequency band.
Two low-mid speakers arranged side by side at a wavelength interval, and interposed between the acoustic signal source and the low-mid speakers, and the sound waves emitted from the low-mid speakers in the listening space interfere with each other. A directional loudspeaker, comprising: a medium / low-frequency sound canceling control unit for canceling the sound by the directional high-frequency sound signal from the acoustic signal source. 2. An eighth-wavelength of a sound wave in a control frequency band.
Two low-mid speakers arranged side by side at a wavelength interval, and a sound wave interposed between the two acoustic signal sources and the low-mid speakers and emitted from the low-mid speakers in different regions in the listening space. And a directional treble speaker that emits a sound based on a high-range sound signal from the sound signal source. Directional loudspeaker. 3. The directional loudspeaker according to claim 1, wherein the directional treble speaker comprises an array speaker. 4. The directional loudspeaker according to claim 1, wherein the middle and low-frequency speakers and the directional high-frequency speaker are arrayed speakers. 5. The low-mid speaker includes a mid-tone speaker and a low-tone speaker. The mid-tone speaker is located at the center of the array speaker, and the low-tone speaker is positioned outside the center speaker. The directional loudspeaker according to claim 4, characterized in that: