JPS5983496A - Micophone device - Google Patents

Abstract

PURPOSE:To record sequentially the sound of different talkers, by retrieving the location of a sound source through sweeping, and directing the main axis of the directivity of the entire microphone to the sound source. CONSTITUTION:A delay circuit 8 sweeps the main axis of the directivity pattern, and the delay time of this circuit 8 depends on a frequency of a rectangular wave signal applied via an I/O port 16 by a command signal from a microcomputer 15 set in advance to retrieve the sound source. An analog signal whose amplitude is changed depending on the angle between the sound source and the main axis of the directivity in response to the sweep of the main axis of the directivity pattern is outputted from a mixing circuit 10. The converted digital signal is inputted to the microcomputer 15 via an I/O port 18, and the location of the sound source in the straightly arranged direction involving the microphone 1 is searched. The main axis is directed to the sound source by a delay circuit 9 based on the positional information.

Description

DETAILED DESCRIPTION OF THE INVENTION (Usage!l!r) The present invention relates to a microphone device, and more particularly, to a microphone device that automatically searches for an i-source position at one o'clock and picks up a target sound.

(Prior Art) Needless to say, microphones have conventionally been used to collect audible sounds. In order to capture the relatively distant deviation 5, a uni-directional high-sensitivity microphone or a gun-type narrow-directional microphone is used.

Separately, another method for capturing sounds from relatively far away is to use a device consisting of a concave reflector for collecting sound and a unidirectional microphone installed at its focal point. There is.

Furthermore, apart from the above, sounds other than the target
In order to eliminate as much as possible, microphone (microphone)
Has the ability to think using ideas. This method obtains sharp directivity by arranging multiple microphones at regular intervals in a straight line or on a two-dimensional plane, thereby eliminating noise as much as possible.

In this case, in principle, increasing the number of microbons increases the sharpness of the directivity or the directivity gain. Therefore, according to the idea of using the microphone array, the target sound and other noises can be distinguished and contained.
(for example, recording).

However, conventional microphone devices using a microphone array have a drawback in that the sharper the directivity, the more difficult it becomes to pick up a target sound.

This is because microphone devices using conventional microphone arrays do not have the ability to automatically search and track the sound source, and therefore cannot accurately search for the target sound source, especially when the sound source is moving. , because it cannot be tracked. Therefore, conventionally, microphone devices using microphone arrays have a sharp directivity as a whole, but
Moreover, a microphone device that can automatically search for and track a sound source has been desired.

(Objective) The present invention is intended to meet the above-mentioned needs, and an object of the present invention is to provide a narrow-directional microphone using a microphone array that can automatically search and track a sound source. We are in the process of providing equipment.

(Summary) In order to achieve the above object, the present invention provides (1) a plurality of microphones arranged at predetermined intervals and arranged to form two linear arrays that intersect at the predetermined microphones therein; (2) a plurality of first microphones, which are provided after each of the two microphones forming the two linear arrays, and which delay the output of the microphone by a predetermined time according to a delay time setting signal input thereto; a delay circuit; (3) the first delay circuit so as to periodically sweep (sweep or tL scan) the main axis of the directivity pattern obtained by the microphones forming each of the linear arrays in all directions of the linear array; means for supplying a predetermined delay time setting signal; (4) a first means for mixing each output of the first delay circuit;
(5) a plurality of second mixing circuits provided after the plurality of microphones and delaying the outputs of the plurality of microphones by a scheduled time in accordance with a delay time setting signal input thereto; a delay circuit, (6) which uses the output of the first mixing circuit as an input, detects the sound source position, and also detects the sound source position so that the waves from the sound source that reach the pre-memorized microphones coincide on the time axis. means for supplying a predetermined delay time setting signal to each of the second delay circuits; (7) a second mixer that receives each output of the second delay circuit as an input and outputs a signal obtained by combining the outputs; We decided to provide a circuit and .

Furthermore, in the present invention, in order to achieve the above object, (1)
a plurality of microphones located at known positions; (2) a sample-and-hold circuit provided after at least three microphones among the plurality of microphones to sample and hold output signals of the microphones; (3) an A/D conversion circuit that is provided after each of the sample and hold circuits and converts the output of the sample and hold circuit into a digital signal; (4) converts the digital signal obtained at the scheduled time into data; (5) a plurality of delay circuits provided after the plurality of microphones, each delaying the output of the plurality of microphones by a scheduled time in accordance with a delay time setting signal input thereto; (6) Based on the data stored in the storage means, a predetermined value is applied to each of the i11 delay circuits so that the sound waves from the sound source reaching the plurality of microphones coincide on the time axis. A means for supplying a delay time setting signal; and (7) a mixing circuit that receives each output of the delay circuit as an input and outputs a signal obtained by combining the outputs.

(Embodiment) First, a sound source search method according to a first embodiment of the present invention described below will be explained using the drawings.

FIG. 1 is a directional characteristic diagram showing an example of a directional pattern formed by linearly arranged (linearly arranged) microphones.

On a plane (here, the plane corresponding to the paper surface) including the linear array I formed by arranging a plurality of (five in this case) microphones, the directional pattern superimposed by the plurality of microphones is, for example, It is sharp like B in Figure 1.

On the other hand, in a plane perpendicular to the linear array (r (plane) perpendicular to the plane of paper in this case), a directivity pattern almost the same as - microbons is obtained. In other words, this directivity pattern is generally broad. .

Note that in the figure, b is the main axis of the directional pattern B.

Generally, when d/λ (d is the micro-bon spacing, λ is the wavelength of the sound wave) is less than 1, the side lobes of the directional pattern become small and the pattern becomes almost unidirectional.

Next, an output signal path K and a delay circuit are provided for each of the microbons forming the linear array I, and when the delay time for the output signal is varied at a predetermined rate for each microphone, the linear An image of the array process is, for example, straight lines 3 and 4 shown by broken lines in FIG. That is, the image of the linear array I can be changed to look like straight lines 3 and 4.

For example, in the case of straight line 3, such a change causes a delay time difference O
This can be done by proportionally distributing the maximum value of the delay time difference according to the distance between the microphone (the microphone on the left end of the drawing) and each microphone other than the microphone with the maximum delay time difference (the microphone on the right end of the drawing). The same applies to the Ia line 4. Furthermore, if the same delay time is given to each microphone, then the image of the linear array (2) becomes like the straight line 2.

Therefore, from the above explanation, it can be said that if the delay time of the output signal of each microphone is continuously changed at a predetermined rate, the directivity pattern obtained by the microphones forming the LU wire array 11 , it changes like A-+B-+C or C-3→A in FIG. That is, the main axis of directivity is a−+
It can be changed as follows: l)→C or C→b→a, making it possible to scan a plane including the linear arrangement.

By the way, if the main axis of directivity swings by a maximum of 60 degrees to the left and right due to the change in the image of the linear array of microphones (■) as described above, then the distance between each microphone (provided that the microphone spacing d is 30σ) is The maximum delay time difference is 6.1 m seconds.

By the way, when the sound source S1 is located, for example, at the position marked ■ in FIG.
, f, the amplitude of the output signal of each microphone forming the linear array I becomes the maximum value.

Therefore, the delay time of each microphone is
If the value is fixed to a value that allows formation of the sound source S1, only the sound waves mainly emitted from the sound source S1 can be collected, and other noises etc. can be excluded.

Next, regarding the sweeping force θpe of the principal axis of the directivity pattern,
The crystals will be further explained using FIG.

In addition, in the same figure, ■ indicates microphones M1 to M5.
represents a linear array formed, for example, on the ceiling of a room, and J represents microphones ml, m2, M3 . 1 shows a line between wires formed by m4 + m5. 2 is the linear array I, J
The axis line extends vertically downward from the intersection point (here, microphone M3).

As explained above, the directivity pattern obtained by a linear array of microphones is, for example, first considering a linear array I as an example, a surface (1-Z
However, the lcg is sharp. Also, in the plane perpendicular to this IM line array ■<I-J [drunk, J-Ztdrunk),
It becomes a broad (fan-shaped pattern).

By the way, the sound source position obtained by scanning the 11t1 fan-shaped pattern in the linear array I direction is one-dimensional positional information. In order to obtain two-dimensional sound source position information, after obtaining the one-dimensional position information, the microphones m 1 + m 2 r M 3 + m 4 r forming a linear array J are
m5 creates a sharp directional pattern D on the J-2 plane.
It is necessary to scan the main axis d in the direction of the linear array J.

That is, the exact location of the sound source can only be known through the two-stage scanning described above. Note that, as is clear from the explanation of FIG. 1, the direction of the main axis of directivity is controlled by the delay time of the delay circuit.

By the way, from the perspective of this delay time, the above 2.
The dimensional sound source position information can be obtained by alternately repeating the delay time setting of each microphone forming the linear array III and the delay time setting of each microphone forming the linear array J.

Here, the operating principle of the first embodiment of the present invention, which will be described below, including the method of sound source searching described above, will be summarized.

(1) Use a microphone array to pick up the target sound source.

(2) The output signal of each microphone is divided into two paths, and the output signal of the first path is given a delay whose N delay time changes periodically to obtain the main directivity of 4f from the entire microphone array. 4! Change ll. That is, as described above, f(subtraction) is performed to search for the position j# of the sound source.

(3) Once the position of the f source is determined, a predetermined delay is given to the output signal of the second path based on it, so that the main axis of directivity of the entire microphone points in the direction of the sound source.

FIG. 3 shows the main parts of the first embodiment of the microphone device of the present invention, and in particular, the sound source position search will be specifically explained.

In FIG. 3, a signal output from a microphone 1 is amplified by a microphone amplifier 5 and delayed by a first delay circuit 8 made of, for example, a BBD element. This delay circuit 8 is for scanning the main axis of the directivity pattern, as described above, for the purpose of searching the position of the sound source. By the way, the delay time of this delay circuit 8 is determined by proportionally distributing the maximum value of the delay time difference according to the distance between the microphone 1 and the microphone with a delay time difference of 0, as described above. That is, the microcomputer (c p ) t is set in advance so that the sound source position can be searched by the directivity principal axis scanning obtained by each microphone forming a linear array including microphone 1.
It is determined by the frequency of the rectangular wave signal (delay time setting signal) supplied via the Ilo port 16 by the command signal from 5.

Note that this rectangular wave signal is supplied to the delay circuit 8 via a path 13.

Furthermore, the delay times of the respective delay circuits provided corresponding to the other microphones forming the linear array including microphone 1 are similarly set. Further, the delay time of each delay circuit provided corresponding to each microphone forming a linear array orthogonal to the 1αα line array, which will be described later, is similarly set.

Next, the output signal of the first delay circuit 8 is supplied to the first mixing circuit 1° together with the output signals of each of the other linearly arranged microphone circuit systems including the microphone 1. Therefore, the mixing circuit 1o outputs an analog signal whose amplitude changes depending on the intensity of the sound, that is, the angle between the sound source and the main axis of the directivity, in accordance with the scanning of the main axis of the directivity pattern. Become. Note that the scanning needs to be performed at a faster speed than the change in the sound source position.

This analog signal then goes from 500 flz to 11c
A/I)
The signal is input to a converter (circuit) 19 and converted into a digital signal. This digital signal is Ilo port 1-1
8, the signal is input to C915, where the sound source position H in the linear arrangement direction including the microphone 1 is detected.

By the way, as mentioned above, in order to obtain each directivity pattern necessary for scanning in the planned direction, a set of command signals (digital signals) corresponding to the rectangular wave signals to be supplied to each delay circuit is prepared in advance. Multiple sets (for example, 1 to 100) are set.

Therefore, the detection of the sound source position by this C115 is performed using the digital signal (this is designated as data number l; (where i is one from 1 to 100).

By the way, the above explanation was about the principal axis scanning of the directivity pattern in the direction of the linear array (here, this is referred to as the aforementioned linear array ■) including the microphone 1.
In order to obtain the two-dimensional f source position 1M information, as mentioned above, it is necessary to The directivity pattern QJ gI axis 1 inspection needs to be performed in the same way as the main axis scanning of the directivity pattern in one direction of the linear array.

According to the main axis Rh M of this latter directivity pattern,
The position of the sound source in the J direction of the linear array, the digital signal (data number j, where j is one from 1 to 100) corresponding to the one with the largest amplitude ψM among the analog signals with 4 f and 15 mantissas. Can be detected.

Therefore, the data number i detected as above
, j, it is possible to know the exact location of the sound source.

Next, in FIG. 3, the output signal of the microphone amplifier 5 is
Similarly to the first delay circuit 8, B is connected to the path 6.
The signal is supplied to a second delay circuit 9 consisting of a BD element. This delay circuit 9 is for directing the main axis of the directivity of the microphone 1 in the direction of the position of the sound source, based on the position information of the sound source determined by the above-described main axis scanning of the directivity pattern.

By the way, as will be described later, the delay time of this delay circuit 9 is supplied to the second delay circuit 9 via the Ilo boat 17 and the path 12 based on the command signal obtained as a result of the calculation of C15. It is determined by the frequency of the rectangular wave signal.

In addition, from the Ilo port 17, a signal is supplied to each microphone constituting the microphone device and a delay circuit (a delay circuit equivalent to the second delay circuit 9) provided after the microphone amplifier connected thereto. A rectangular wave signal (delay time setting signal) is output. The frequency of this rectangular wave signal is such that the main axis of the directivity obtained from the entire microphone constituting the microphone device is directed toward the sound source, based on the sound source search results described above.

By the way, the path 14 is for supplying the output signal of the second delay circuit 9 to the second mixing circuit, as is clear from i51ffl described later.

Next, a method for calculating and deriving the frequency of a rectangular wave signal that directs the main axis of directivity of the entire microphone in the direction of the position of the sound source will be described with reference to the drawings.

FIG. 4 is a microphone arrangement diagram showing an example in which 17 microphones are arranged on a two-dimensional plane.

For example, when the position of the sound source SI is (++j+2°) and the position of each microphone is (i'+j''+0), the distance Li'j' between the microphone and fi is expressed by equation (1).

Note that 1 here is the data number 1 (i = 1
．． 2. . . . m), and j is the data number j (j=1. 2.・
・・・・・・・・・ j corresponding to m). In addition, Zo is the surface where the microphones are arranged, that is, I-J
Indicates the distance from the surface to the sound source.

Also, the distance I, il j between each microphone and the sound source
If the maximum value of l is Lmax, then the propagation time difference T I between the microphone of Lmax and other microphones is
l jl is expressed by equation (2).

Ti'j'-(Lrnax-Li'j')/
340.0 (S) --- (2) Once this propagation time difference Ti'j' is derived, the frequency of the rectangular wave signal supplied to each second delay circuit is generally (3) It is expressed by the formula.

fl+ jI=ty/'r11jl+l) ・・・-・
・・・・・・ ・ ・・・・・・・・・・・・ Song use ・
+31 Note that here, a r b is a fixed value determined for each microphone device using a microbon array.

That is, as described above, the frequency σI/Ir9 . can be determined.

Next, a first example of the microphone device of the present invention is shown in a flow side view, and will be explained and explained.3 In the same figure, the same parts as in FIG. Parts are indicated by the same reference numerals.

24 and 25 are the first microphones connected to each microphone system.
and a second delay circuit (corresponding to delay circuit 8.9 in FIG. 3) are grouped together as a first and second delay circuit block.

As described above, the first delay circuit block 24 performs principal axis scanning of the directivity pattern in order to search for a sound source. A rectangular wave (No. 8 is supplied to each delay circuit constituting the delay circuit block 24, as described above, Ilo
Output via port 16. It is clear from the above explanation that the frequency of this rectangular wave signal differs for each microbon system and changes over time.

- The second delay circuit block 25 is for directing the main axis of the directivity pattern of the entire microbon toward the sound source. The rectangular wave signal that sets the delay time of each delay circuit constituting this delay circuit block 25 is C1
5, the signal is supplied from the Ilo port 17 in response to the calculated command signal, as explained in FIG.

γj The frequency of this rectangular wave Ig differs for each microphone system, but is constant over time unless the position of the sound source changes.

The respective output signals of the microbond type delay circuits of the second delay circuit block 25 are supplied to the second mixing circuit 20 and mixed there. The output of this mixing circuit 20 is sent to the speaker system 2 via a bandpass filter 21 having a band of 200H7 to 5kI (corresponding to the z band (corresponding to the high frequency band) and a main amplifier 22.
3. As a result, the speaker system 23 outputs sound.

Next, the input/output of signals and the order of calculations in C115 will be explained using the flowchart shown in FIG.

The alarm source of the microphone device shown in FIG. 5 is turned on, and C
When the calculation starts at step S1, first, as mentioned above, the main axis of the directivity obtained by each microphone forming the linear array 1 is
A command signal for sweeping in the straight line alignment direction is output.

In step S2, data obtained by scanning the IH line array I is input manually in accordance with the first command.

Next, in step S3, as described above, the linear array J
The main axis of directivity obtained by each microphone forming the
A command signal is output that causes scanning to be performed in the J direction of the linear array.

In step S4, data obtained by scanning the linear array J direction in response to the command signal is input.

Next, in step S5, if the maximum value of the data obtained by scanning the 1a line array ■ and the J direction (corresponding to the one with the largest amplitude among the plurality of analog signals described above) is greater than or equal to the predetermined value. It is determined whether there is a sound source or not, and if the expected value has not been reached, it is determined that there is no sound source and the process returns to step S1. If the scheduled value has been reached, the process advances to step S6.

In step S6, the position of the sound source is determined from the maximum value of the data obtained by scanning the curved line arrays I and J directions (specifically, data numbers i and j mentioned in 611).

In step S7, it of the above-mentioned equations (1) to (3) is
Let fi go γS.

In step S8, III'I! of step S7! 4
Based on the results, the main axis of directivity of the entire microphone is
Outputs a command signal 4 to direct toward the sound source.

Note that after that, the process returns to step S1 again.

By the way, when a command signal is output in step S8 to direct the main axis of the directivity of the entire microbon toward the sound source direction based on calculation result #1 in step S7, a new calculation is performed in step S7. The output does not change unless a result is obtained.

In the embodiment shown in FIG. 5 (first embodiment), according to the experimental results of the present inventor, after starting the flowchart shown in FIG. 6, the flowchart shown in FIG. It took about 0.2 seconds.

In addition, in this first embodiment, the position of the sound source is searched by scanning the main directivity axes of the microphones that form a linear array that is orthogonal to each other. Of course, the location can be searched. Furthermore, in this first embodiment, the frequency of the rectangular wave signal that directs the main axis of directivity of the entire microphone toward the sound source is determined by a microcomputer, but this is not necessarily limited to a microcomputer. It can also be done by other circuit systems.

Next, another embodiment (second embodiment) of the microphone device of the present invention is shown in FIG. 7, and will be described. In the figure, A1 to A5 are microphones arranged in a straight line;
31a to 35a are sample/hold amplifiers (S/
HT nbu), 31b-85b is the A/D conversion circuit, 31c
~35c is a delay circuit consisting of BBD or CCD, 4
2.43 is an I10 port, 44 is C2, 45 is a mixing circuit, 46 is an output terminal, and 47 is a memory.

In FIG. 7, the outputs of microphones A1 to A5 are:
After being sampled and held in the S/H amplifiers 31a to 35a, the A/D conversion circuit 31b
~35b is converted into a digital signal. This digital signal is connected to Ilo port 42 and C24.
4 and stored as data in the memory 47. The above operation is performed for a preset time (data addition time) t.
ccontinued.

Next, in C144, a cross-correlation function Cij is calculated according to equation (4) using the data.

C1j(τ)”P, :1 (t)X1g (10τ)
/N ・・・・・・・・・・・・・・・・・・・・・
(4) However, here, E4 is the microphone A1~
The output value of one microphone 1 in A5, Ej is the output value of one microphone j (l~
j) output value, τ is the interval time (lag).

N is the number of data.

As shown in FIG. 8, the cross-correlation function C1j takes a maximum value when the lag τ is equal to jt. Here, T, l are for microphone i at time ti and for microphone j at time t
, j represents the time difference between the arrival of sound waves from the sound source.

Further, as is clear from equation (5), if the time difference Tjl is positive, it indicates that the output of the microphone j lags behind the output of the microphone 1 by Tji. Conversely, if the time difference Tji is negative, it indicates that the output of microphone i lags behind the output of microphone j by Tlj.

Tjl = TjTi ・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・(5) Therefore, with a suitable one of the microphones A1 to A5, for example, microphone i, as a reference, the time difference Ti between this microphone i and the other microphones is
j can be determined from the cross-correlation function.

By the way, in FIG. 7, when the time difference T8j with each other microphone is derived using microphone A3 as a reference, the above Tgj(Tllll + T82 + TB8
+TH4+Tl1s) is, for example, 1j as shown in FIG.

In order to direct the main axis of the directivity of the microphone array from microphones A1 to A5 toward the sound source, precisely, the output of each of the microphones A1 to A5 is directed to the time axis through a delay circuit. Must match above. At this time, the reference is the microphones A1 to A.
Among the microphones 5 and 5, this is the microphone with the maximum negative time difference TIj of 4f.

(In the embodiment of FIG. 7, as is clear from FIG. 9, it is necessary to set the delay time for each microphone based on the time difference T8 of microphone A5. Specifically, is the absolute value of Tss (length of the arrow)
, each T s, 4 (T8, + Ta2 + T0n
r T841T1,), the 10th
The figure shows TT5゜(Ts+1"'521 Tss+
T54 + '14B) for each microphone A1~
It can be set as the delay time of the delay circuits 31c to 35c of A5. That is, the command signals corresponding to each T5j shown in FIG. 10 are sent from C244 to Ilo.
It will be output to port 43.

As mentioned above, in FIG. 7, the delay circuits 31c to 3
Since 5c is composed of a BBD or a CCD, the delay time can be continuously varied depending on the frequency of the rectangular wave signal (delay time setting signal).

That is, when fi is the delay time of one of the delay circuits 31c to 35c and fi is the frequency of the rectangular wave signal, the relationship between them is as shown in equation (6).

τ,=to/f,・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
(6) However, K here is a proportionality constant determined for each delay circuit.

Therefore, from the Ilo port 43, corresponding to the command signal, and in each delay circuit 31c to 35c,
A rectangular wave signal having a frequency that provides a predetermined delay is output.

It goes without saying that the frequency fl of the rectangular wave signal set as described above will not change unless the sound source position moves and, as a result, a corresponding command signal is applied from Cp44. .

Moreover, as is clear from FIG. il1, the frequency fl of the rectangular wave signal is equal to the data acquisition time t.

It can be changed every time tT, which is the addition of the calculation time tD in C944 described above.

By the way, in FIG. 7, each microphone A1 to A5
As mentioned above, the outputs of the delay circuits 31c to 35c
, each signal is delayed by a predetermined time and supplied to the mixing circuit 45. Therefore, at the output terminal 46, the outputs of the microphones A1 to A5 completely match on the time axis, and a superimposed signal is obtained.

Next, nine main operations in the embodiment shown in FIG. 7 will be further explained using the flowchart shown in FIG.

In FIG. 7, when audio signals are output from each of the microphones A1 to A5, in step S1, the outputs are sampled and held in the S/)I amplifiers 31a to 35a.

Next, in step S2, A/D conversion circuits 31b to 3
5b, the outputs of the S/H amplifiers 31a to 35a are converted into digital signals.

In step S3, the digital signal is stored as data in the memory 47 via the I10 port 42 and Cp44.

Next, in step S4, it is determined whether the maximum value of the data stored in the memory 47 in step S3 is greater than or equal to the planned value, and if it has not reached the planned value, it is determined that there is no sound source and the process returns to step S1. . If the planned value has been reached,
Proceed to step S5.

In step S5, based on the data in step S3,
Cp44 performs the following calculations 12 and outputs a command signal.

(1) First, the respective cross-correlation functions C, .

(2) From the calculation results of the cross-correlation function, derive the respective time differences Tlj between the reference microphone 1 and the other microphones j.

(3) Next, by adding the absolute value of the maximum negative value of the time a T 1j to each 'l' 1j, a command signal corresponding to the required delay time of each microphone is generated to the I10 boat 43. Output to.

In step S6, in the I10 boat 43, from the command signal and equation (6), each delay circuit 3]c to 35c
Set and output the frequency of the square wave signal to be output to.

The main operations of the embodiment shown in FIG. 7 are as described above.
I) When steps 81 to S6 described in 11 are completed, the process returns to step S1 and the same operation is repeated.

In the embodiment shown in FIG. 7, there are five microphones, but as is generally well known in a microphone device using a microphone array, any number of microphones may be used as long as it is three or more. , and the arrangement can be arbitrary.

Further, the delay time setting for each microphone may be calculated based on the position of each microphone and the time difference between any three microphones.

In this way, even if there are three or more microphones, three S/H amplifiers and three A/D conversion circuits each are sufficient.

(Effects) As is clear from the above explanation, according to the present invention, in a narrow directional microphone device using a microphone array,
It has the effect of automatically searching and tracking the sound source.

Therefore, if the microphone device of the present invention is used in a small hall, conference hall, etc., it is possible to successively pick up the speeches of different speakers, and to eliminate noises other than the sound source.

[Brief explanation of drawings]

Fig. 1 is a directional characteristic diagram showing an example of a directional pattern formed by linearly arranged microphones; Fig. 2 is an orthogonal microphone arrangement diagram for explaining a method of principal axis scanning of a directional pattern; Figure 4 is a block diagram showing the main parts of the first embodiment of the microphone device of the present invention, Figure 4 is a microphone arrangement diagram showing an example of arranging microphones on a two-dimensional surface, and Figure 5 is the microphone device of the present invention. 1. FIG. 6 is a block diagram showing the first embodiment of the present invention, FIG. A block diagram showing a second embodiment of the microphone device, FIG. 8 is a characteristic diagram showing the relationship between the cross-correlation function and the lag τ, and FIG. 9 is a diagram for clarifying the time 1tjl difference between each microphone. , FIG. 1O is a diagram for explaining the delay time set in each delay circuit, and FIG. 11 is a diagram for explaining the data acquisition time t. A diagram for explaining the relationship between the time tT and the frequency f1 of the rectangular wave signal with the addition of the paralysis time 1)).
FIG. 12 is a flowchart for explaining the operation of FIG. 7. 1, A1-A5...microphone, 8,9...first
and a second delay circuit, 10. ．． 20...First and second mixing circuit, 15.44...Microcomputer, 16-18°42, 43...rlo hole
19, 31 b to 35 b-A/D conversion circuit, 24.25...first and second -i' extending circuit block, 31a to 35a...→non-pull bold amplifier, 31cm35 c. ...Delay circuit, 47...Memory agent Michihito Hiraki-607-n) Figure 5 Figure 6 Figure 7 Figure 8-Tii OTji Figure 9 Figure 1Q
Figure -0+ -0+ Figure 11 Frequency f- of the eyebrow-shaped signal. tTtTtTt4 -----

Claims (2)

[Claims] (1) A plurality of microphones arranged at predetermined intervals to form two linear arrays that intersect at the predetermined microphones, and a rear stage of each microphone forming the two linear arrays. a plurality of first delay circuits, each of which delays the output of the microphone by a predetermined time according to a delay time setting signal input thereto; and a main axis of a directivity pattern obtained by the microphones forming each linear array. A predetermined M is applied to the first delay circuit so as to periodically sweep in the linear arrangement direction.
a first mixing circuit for mixing each output of the first delay circuit; a plurality of second delay circuits that respectively delay the outputs of the plurality of microphones by a predetermined time according to the inputs thereof and the output of the first mixing circuit, detect the position of the sound source, and means for supplying a predetermined delay time setting signal to each of the second delay circuits so that the arriving sound waves from the sound source coincide on the time axis; each output of the second delay circuit is input; A microphone device comprising: a second mixing circuit that outputs a signal obtained by combining the outputs. (2) a plurality of microphones located at known positions; a sample and hold circuit provided after at least three of the plurality of microphones to sample and hold output signals of the microphones; - an A/D conversion circuit provided after each of the hold circuits and converting the output of the sample/hold circuit into a digital signal; and means for storing the Ail digital signal obtained at the scheduled time as data; a plurality of delay circuits each provided after the microphone on the f-counter number side and delaying the output of the plurality of microphones by a scheduled time in accordance with a delay time setting signal input thereto; means for supplying a predetermined delay time setting signal to each of the delay circuits so that the V waves from the sound source reaching the plurality of microphones coincide on the time axis based on the data; 11] A microphone device comprising a mixing circuit which receives each output of the delay circuit as an input and outputs a signal obtained by combining the outputs.