JPH06204771A - Pickup sound wave device - Google Patents

Abstract

PURPOSE:To improve the S/N by executing pickup sound waves while emphasizing the object sound to be subjected to pickup in a direction, thereby enhancing a level of the object sound relatively more than an undesired sound level in the sound pickup method by using plural microphones. CONSTITUTION:Plural unidirectional microphones 1-4 are used for the pickup, and sound source direction detection means 5 detects the direction of an object sound based on an output signal of the microphones subjected to the pickup and a signal control means 6 adjusts the gain of the output signal of the microphones and the frequency characteristic based on the signal indicating direction detection. Then the pickup sound waves are executed while the sound is emphasized in the direction of the object sound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound pickup device for picking up sound by a microphone, such as a video recording device with a built-in camera and a high-definition television.

[0002]

2. Description of the Related Art In recent years, a system capable of transmitting a plurality of channels for audio as seen in high-definition has been developed. In addition, there is an increasing demand for a camera-integrated video recording device to collect only a desired sound.

A conventional sound collecting device will be described below with reference to the drawings. FIG. 11 is a block diagram showing a conventional sound collecting device. FIG. 12 is a diagram showing a maximum sensitivity direction of a microphone of a conventional sound collecting device that collects sound by the MS stereo system.

In FIG. 11, 100 is a unidirectional microphone for the left channel, 101 is a unidirectional microphone for the right channel, 102 is a unidirectional microphone for the center channel, and 103 is a unidirectional microphone for the left channel. Subtraction means for taking the difference between the output L of 100 and the output R of the right channel unidirectional microphone 101,
104 is a gain adjusting means for adjusting the gain, 105 is an adding means for adding the gain-adjusted signal and the output signal M of the central channel unidirectional microphone 102, and 106 is a signal whose gain is adjusted by the gain adjusting means 104. And subtracting means for subtracting the output signal M of the unidirectional microphone 102 for the center channel, 107 is an output terminal for the L'signal to be reproduced in the left channel, and 108 is an R'signal to be reproduced in the right channel. Output terminal.

The operation of the conventional sound collecting device configured as described above will be described. First, the MS microphone including the unidirectional microphones 100, 101 and 102 is installed in the sound field to be picked up. The configuration of the MS microphone will be described later. The signal L from the unidirectional microphone 100 for the left channel and the signal from the signal R from the unidirectional microphone 101 for the right channel are subtracted by the subtracting means 103, and become equivalent to the bidirectional microphone. The output of the subtraction means 103 is gain-adjusted by the gain adjustment means 104, the gain-adjusted signal is added to the output M of the central channel unidirectional microphone 102 by the addition means 105, and the gain-adjusted signal is subtracted by the subtraction means 106. To the output M of the unidirectional microphone 102 for the center channel
Subtract.

Next, the structure of the MS microphone will be described. FIG. 12 is a diagram showing the configuration of the MS microphone. In FIG. 12, the microphone is installed so that the maximum sensitivity direction is in the direction of the arrow. In FIG. 11, 1
00, 101, and 102 are unidirectional microphones. The unidirectional microphone 102 is called a Mid microphone, and the bidirectional microphone composed of the unidirectional microphones 100 and 101 is called a Side microphone.

The operation of the MS stereo type sound collecting device configured as described above will be described.

As shown in FIG. 12, a single unit for the center channel is used.
Set the maximum sensitivity direction of the unidirectional microphone 102 to the positive direction of the Y axis.
Directionally unidirectional microphone for left channel 1
00 directional axis and unidirectional microphone for right channel
The axis connecting the directional axes of 101 is the X axis, for the right channel
The direction of maximum sensitivity of the unidirectional microphone 101 is positive
Take to the other side. Also, the positive direction of the X-axis is set to 0 °, and it is rotated counterclockwise.
If the angle θ is defined so that
Directivity D of the black phones 100, 101, 102
_L(Θ), D_R(Θ), D_M(Θ) is shown in FIG.
Shown in (b) and (c), (Equation 1), (Equation 2), Equation 3)
It is represented by.

[0009]

[Equation 1]

[0010]

[Equation 2]

[0011]

[Equation 3]

As shown in FIG. 12, the output of the unidirectional microphone 100 for the left channel and the output of the unidirectional microphone 101 for the right channel are subtracted by the subtracting means 103, and the output is represented by (Equation 4). Directional characteristics D _LR (θ)
have.

[0013]

[Equation 4]

This is equivalent to the directional characteristics of the bidirectional microphone having the directional characteristics shown in FIG. Subtraction means 103
Is multiplied by α by the gain adjusting means 104, and the adding means 10
At 5, the sum is added to the output of the unidirectional microphone 102 to form the left channel side output signal L '. Further, the output of the gain adjusting means 104 and the output of the unidirectional microphone 102 are subtracted by the subtracting means 106 to become the right channel side output signal R '. The directivity characteristics D _L ′ (θ) and D _R ′ (θ) of the left channel side signal L ′ and the right channel side signal R ′ are
It is expressed by (Equation 5) and (Equation 6).

[0015]

[Equation 5]

[0016]

[Equation 6]

When α is changed, the sensitivity of the signals L'and R'changes. FIG. 14 shows D _L ′ (θ) and D _R ′ (θ). However, α = 1/2.

[0018]

However, in the above-mentioned conventional configuration, there is a drawback that the target sound to be picked up and the unnecessary sound are picked up at the same level and the S / N is deteriorated. That is, it was not possible to pick up only a specific sound like the cocktail party effect.

The present invention solves the above-mentioned conventional problems. By emphasizing the gain in the direction of the target sound to be collected, the target sound level is relatively higher than the unnecessary sound level. Since it becomes higher, S / N can be improved. Furthermore, the S / N can be further improved by controlling not only the gain adjustment in the direction of the target sound but also the directional characteristics. further,
An object of the present invention is to provide a sound pickup device that can further emphasize a target sound by giving unnecessary sound a frequency characteristic.

[0020]

In order to solve the above-mentioned problems, a sound collecting device of the present invention inputs a plurality of unidirectional microphones and the output signals of the plurality of unidirectional microphones to generate a sound source. A sound source direction detecting means for detecting a direction; and a signal control means for controlling the gains of the output signals of the plurality of unidirectional microphones with the output signal of the sound source direction detecting means as an input. It is a thing.

Further, the signal control means controls the gains of the output signals of the plurality of unidirectional microphones, or the signal control means controls the gains of the output signals of the plurality of unidirectional microphones. The frequency characteristics are controlled.

Further, the sound collecting device of the present invention has a plurality of unidirectional microphones, an omnidirectional microphone, and a sound source for inputting output signals of the plurality of unidirectional microphones and detecting the direction of the sound source. And a matrix device for calculating the plurality of unidirectional microphones and the omnidirectional microphone signals and controlling the calculated signals by using the output signal of the sound source direction detecting means as an input. It is characterized by that.

Further, the matrix device is characterized by controlling the gain of the calculated signal, or the matrix device is characterized by controlling the gain and frequency characteristic of the calculated signal. .

[0024]

According to the present invention, with the above-described structure, a plurality of unidirectional microphones collect sound, the sound source direction detecting means detects the direction of the target sound, and the signal processor adjusts the microphone gain and frequency characteristics. The target sound direction can be emphasized to collect the sound. In addition, a plurality of unidirectional microphones and omnidirectional microphones are used to pick up the sound, and the sound source direction detecting means detects the direction of the target sound, and the matrix device not only adjusts the gain and frequency characteristics but also the directional characteristics of the output signal. By controlling also, it is possible to further emphasize the target sound direction and collect the sound.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The first embodiment is a sound pickup device that picks up sound by using four unidirectional microphones.

FIG. 1 is a block diagram showing the structure of a sound collecting device according to the first embodiment of the present invention. FIG. 2 is a diagram showing the maximum sensitivity direction of the microphone. Install so that the maximum sensitivity of the microphone comes in the direction of the arrow.

In FIG. 1, 1 is a unidirectional microphone for the left channel, 2 is a unidirectional microphone for the right channel, 3 is a unidirectional microphone for the center channel, and 4 is a unidirectional microphone for the surround channel. A unidirectional microphone, 5 is a sound source direction detecting means for detecting a direction of a target sound to be picked up from outputs L, R, C, S signals of the unidirectional microphones 1 to 4, and 6 is a sound source direction detecting means 5.
The signal control means 26, 27, 28 and 29 for controlling the output signals of the unidirectional microphones 1 to 4 according to the output of the sound pickup signals L ', R', and
C'and S '.

The sound source direction detecting means 5 is composed of the following elements. Reference numerals 7, 8, 9, 10 denote full-wave rectification circuits for full-wave rectifying the output signals of the unidirectional microphones 1, 2, 3, 4 respectively, and 11 has a logarithmic difference D _LR between the L signal and the R signal. Logarithmic difference circuit, 12 is a logarithmic difference D between the C signal and the S signal
_A logarithmic difference circuit taking _CS , a threshold switch 13 for judging whether the output of the logarithmic difference circuit 11 or the logarithmic difference circuit 12 is within a predetermined range, 14
Is a dual time constant circuit that processes the output D _LR of the logarithmic difference circuit 11 with a low-pass filter having a time constant of 22 [ms] or 484 [ms] according to the determination result of the threshold switch 13, and 15 is the determination of the threshold switch 13. This is a bi-time constant circuit that processes the output D _CS of the logarithmic difference circuit 12 with a low-pass filter having a time constant of 22 [ms] or 484 [ms] according to the result.

Further, the signal control means 6 is composed of the following elements.
Is made. 16 is a coefficient according to the output of the bi-time constant circuit 14.
E_L, E_RTo generate a coefficient according to the output of the bi-time constant circuit 15.
Number E _C, E_SA gain adjusting means control circuit for producing
Coefficient F according to the output of the time constant circuit 14_L, F_RCreate
Coefficient F according to the output of the bi-time constant circuit 15_C, F_SCreate
A frequency characteristic adjusting means control circuit, 18 is a gain adjusting means control circuit.
Coefficient E of control circuit 16_LGain that multiplies the L signal by a constant
The adjusting means 19 is a coefficient E of the gain adjusting means control circuit 16._R
A gain adjusting means for multiplying the R signal by a constant in accordance with
Coefficient E of adjusting means control circuit 16_CConstant C signal according to
Gain adjusting means for doubling, 21 is a gain adjusting means control circuit 16
Coefficient E of_SAccording to the gain adjustment means for multiplying the S signal by a constant
is there. Further, 22 is a frequency characteristic adjusting means control circuit 17.
Coefficient F_LThe frequency of the output signal of the gain adjusting means 18 according to
Frequency characteristic adjusting means for adjusting the characteristic, 23 is a frequency characteristic
Coefficient F of adjusting means control circuit 17_RGain adjustment means according to
Frequency characteristic adjustment for adjusting frequency characteristic of 19 output signal
Means 24 is a coefficient F of the frequency characteristic adjusting means control circuit 17
_CAccording to the frequency characteristic of the output signal of the gain adjusting means 20.
Frequency characteristic adjusting means for adjusting, 25 is a frequency characteristic adjusting hand.
Coefficient F of the stage control circuit 17_SOf the gain adjusting means 21 according to
With the frequency characteristic adjusting means for adjusting the frequency characteristic of the output signal
is there.

The operation of the sound collecting device configured as described above will be described below.

The outputs L, R, C, S of the unidirectional microphones 1, 2, 3, 4 take the logarithmic difference of the signal level with respect to the LR axis or the CS axis by the sound source direction detecting means 5, and the difference is calculated. Originally, the signal from which direction is dominant is detected. Then, the signal control means 6 outputs the signal in the dominant direction as it is, attenuates the signal in the other directions, and passes only the low-frequency component to make it feel like a sound. Emphasize the sense of sound direction.

First, the microphone will be described.
Here, for convenience, the directional axis of the unidirectional microphone 3 for the center channel (or the directional axis of the unidirectional microphone 4 for the surround channel) is taken as the y-axis, and the unidirectional microphone 3 for the center channel and the unidirectional microphone for the surround channel are used. With the middle point connecting the unidirectional microphone 4 as the origin,
The axis orthogonal to the y axis at the origin is defined as the x axis. At this time, the maximum sensitivity direction of the unidirectional microphone 3 for the center channel and the maximum sensitivity direction of the unidirectional microphone 2 for the right channel are defined as positive directions of the respective axes. Further, θ is an angle in which the positive direction of the x axis is 0 ° and the counterclockwise direction is positive.

For example, as shown in FIG. 2, the directivity characteristic D _L (θ) of the L signal is in the 135 ° direction, and the directivity characteristic D of the R signal is
_It is assumed that _R (θ) has the maximum sensitivity in the direction of 45 °, the directivity characteristic D _C (θ) of the C signal in the direction of 90 °, and the directivity characteristic D _S (θ) of the S signal in the direction of 270 °. . The respective directional characteristics are shown in (Equation 7), (Equation 8), (Equation 9), (Equation 10).

[0034]

[Equation 7]

[0035]

[Equation 8]

[0036]

[Equation 9]

[0037]

[Equation 10]

The directional characteristics of (Equation 7) to (Equation 10) are shown in FIG. 3A shows the directivity characteristic D _L (θ) of the L signal, FIG. 3B shows the directivity characteristic D _R (θ) of the R signal, and FIG.
Shows the directivity characteristic D _C (θ) of the C signal, and FIG. 3D shows the directivity characteristic D _S (θ) of the S signal.

Next, the sound source direction detecting means 5 will be described. The L, R, C, and S signals are full-wave rectifier circuits 7 to 10.
Is full-wave rectified. After full-wave rectification, logarithmic difference circuit 1 for each pair of L signal and R signal and C signal and S signal
1 and 12 to obtain outputs D _LR and D _CS . The processes of the logarithmic difference circuits 11 and 12 are represented by (Equation 11) and (Equation 12), respectively.

[0040]

[Equation 11]

[0041]

[Equation 12]

The output D _LR indicates which of the LRs is dominant with respect to the LR axis, and the output D _CS indicates which of the CSs is dominant with respect to the CS axis.

The threshold switch 13 has an L signal and an R signal.
When the level difference between the signal or the C signal and the S signal is large, the short time constant 22 [ms] of the bi-time constant circuits 14 and 15 is selected in order to change each signal of the outputs L, R, C and S quickly. Conversely, when the level difference is small, a long time constant 48
4 [ms] is selected and the L, R, C, and S signals are gently changed. The threshold switch 13 is a dual time constant circuit 1 if the outputs D _LR and D _CS of the logarithmic difference circuits 11 and 12 are both within the threshold level ± Lth.
The time constant of 484 [ms] of 4 and 15 is selected, and when either one is out of the range, the time constant of 22 [ms] is selected. The time constant ([ms]) selected by the threshold switch 13 is shown in (Table 1).

In order to realize (Table 1), the threshold switch 13 has the outputs D _{LR of} the logarithmic difference circuits 11 and 12,
It is composed of four comparators for comparing D _CS with the threshold level ± Lth and an OR circuit for ORing the outputs of the comparators.

[0045]

[Table 1]

The dual time constant circuit 14 integrates the output D _LR of the logarithmic difference circuit 11 with a time constant of 484 or 22 [ms] according to the determination result of the threshold switch 13. The integrator circuit needs an RC integrator or one having a transient characteristic equivalent thereto. The bi-time constant circuit 14 and the logarithmic difference circuit 12 are also included.
The same processing is performed on the output D _CS of the above.

Next, the signal control means 6 will be described. The gain adjusting means control circuit 16 generates control voltages E _L , E _R , E _C , and E _S according to the polarities of D _LR integrated by the bi-time constant circuit 14 and D _CS integrated by the bi-time constant circuit 15. To do. The control voltages E _L , E _R , E _C , and E _S are (Equation 13), (Equation 14),
It is represented by (Equation 15) and (Equation 16).

[0048]

[Equation 13]

[0049]

[Equation 14]

[0050]

[Equation 15]

[0051]

[Equation 16]

(Equation 13), (Equation 14), (Equation 15),
Control voltage E _L of the gain adjusting means control circuit 16 represented by the equation _{(16), E R, E C} , the gain adjusting means in accordance with the E _S 18,1
The gains of 9, 20, 21 are determined, and the outputs of the unidirectional microphones 1, 2, 3, 4 are multiplied.

[0053] Frequency characteristics adjustment means control circuit 17, a control voltage according to the polarity of the integrated D _CS in D _LR and bi time constant circuit 15, which is integrated by double time constant circuit _{14 F L, F R, F} C ，
Generate F _S. Control voltage _{F L, F R, F C} , F S is (number 1
7), (Equation 18), (Equation 19), (Equation 20).

[0054]

[Equation 17]

[0055]

[Equation 18]

[0056]

[Formula 19]

[0057]

[Equation 20]

Here, the frequency characteristic adjusting means will be described. As shown in FIG. 4, the input signal is selectively passed by the control voltage of the frequency characteristic adjusting means control circuit 17 as it is, or is passed through the low-pass filter 30 that passes only the low-frequency component. You can In (Equation 17) to (Equation 20), “1” selects the signal that has passed through the low-pass filter 30, and “0” selects the input signal. Gain adjusting means 18, 19, 20, 2
The output of 1 is the frequency characteristic adjusting means 22, 23, 24, 2
5, the frequency characteristic is adjusted by L ', R', C ',
It is output as each signal of S '.

As described above, it is detected from which direction the signal is dominant on the LR axis or the CS axis. Then, when the dominant direction is detected, the signal in that direction is output as it is, and the signals in the other directions are attenuated,
Furthermore, the sense of direction of the target sound is emphasized by allowing only the low frequency components to pass and making it feel as if it is surrounded by the sound. Therefore, a sound with a clear direction such as a dialogue gives a clear sense of direction. On the other hand, when the dominant direction cannot be obtained, a normal stereo feeling can be obtained.

In this embodiment, the frequency characteristic adjustment is
There are only two types: the input signal is taken out as it is or passed through a low pass filter.
The cutoff frequency of the low pass filter may be changed smoothly depending on the value of the output signal of 15.

Next, a second embodiment of the present invention will be described. In the above-described first embodiment, the signal control means 6 is used as the unidirectional microphone 1 as means for emphasizing the directivity.
The outputs of 4 to 4 were adjusted in gain so that the direction of the target sound was emphasized and the frequency characteristics were adjusted. However, in the second embodiment, a unidirectional microphone and an omnidirectional microphone are used. By calculating the output with a matrix device, not only the gain adjustment but also the directional characteristic is adjusted, and further the frequency characteristic is adjusted to emphasize the directionality of the target sound. FIG. 5 shows a second embodiment.

In FIG. 5, 51 is an omnidirectional microphone and 52, 53, 54 and 55 are unidirectional microphones, and their outputs are represented by O, L, R, C and S, respectively. The outputs L, R, C, S of the unidirectional microphones 52 to 55 are input to the sound source direction detecting means 5 to detect the direction of the target sound, and according to the control signal, omnidirectional and unidirectional. The output of the microphones 51 to 55 is controlled, and the direction of the target sound is emphasized by the gain adjustment and the adjustment of the directional characteristic and the frequency characteristic to collect the sound.

First, the microphone will be described. FIG. 6A is a directional characteristic of the omnidirectional microphone 51, and FIG.
6B is a directional characteristic of the unidirectional microphone 52, FIG.
6C is a directional characteristic of the unidirectional microphone 53, FIG.
(D) is the directional characteristic of the unidirectional microphone 54, FIG.
(E) shows the directional characteristics of the unidirectional microphone 55. As shown in FIG. 6, unidirectional microphones 52, 5
3, the maximum sensitivity directions are arranged opposite to each other, and the unidirectional microphones 54 and 55 are also arranged in the same manner. The directional axes of the unidirectional microphones 52 and 53 and the directional axes of the unidirectional microphones 54 and 55. Are arranged so as to be orthogonal to each other.

Here, the unidirectional microphones 52, 5
The axis connecting the maximum sensitivity directions of 3 is the X axis, the axis connecting the maximum sensitivity directions of the unidirectional microphones 54 and 55 is the Y axis, and the maximum sensitivity direction of the unidirectional microphone 53 and the unidirectional microphone 54 are respectively. The maximum sensitivity direction of is taken to be the positive direction. Further, θ is an angle in which the positive direction of the X axis is 0 ° and the counterclockwise direction is positive. Microphones 51, 52, 53, 5
4, 55 directional characteristics D _O (θ), D _L (θ), D
_R (θ), D _C (θ), and D _S (θ) are given by (Equation 21) and (Equation 2)
2), (Equation 23), (Equation 24), (Equation 25).

[0065]

[Equation 21]

[0066]

[Equation 22]

[0067]

[Equation 23]

[0068]

[Equation 24]

[0069]

[Equation 25]

The above is the description of the microphone. The sound source direction detecting means 5 is the same as that in the first embodiment.

Next, the matrix device 50 will be described.
To do. 56 is a coefficient E according to the output of the sound source direction detecting means 5.
_O, E_C, E_S, E_L, E_RTo create gain adjustment means control times
, 57 from the output L of the unidirectional microphone 52
Bidirectional by subtracting the output R of the unidirectional microphone 53
Output B equivalent to a sex microphone_XSubtraction means for obtaining
Is unidirectional from the output C of the unidirectional microphone 54.
The output S of the microphone 55 is subtracted to obtain a bidirectional microphone.
Output B equivalent to Rohon_YIs a subtraction means for obtaining. 59 is
Output B of subtraction means 57_XAnd the output B of the subtraction means 58_YSubtract
Subtracting means 60, 60 is the output B of the subtracting means 57_XAnd subtraction hands
Output B of stage 58_YIs an addition means for adding. 61 is profit
Coefficient E of the gain adjusting means control circuit 56_ODepending on the omnidirectional
Adjust the gain of the output O of the microphone 51 to E₀Go GO
A gain adjusting means 62, and 62 an output E of the gain adjusting means 61.₀G
63 is an addition means for adding O and the output of the subtraction means 59.
Output E of gain adjusting means 61₀Output of GO and addition means 60
And 64 is an output of the gain adjusting means 61.
E₀Output B of GO and subtraction means 58_YAdder that adds and
And 65 is the output E of the gain adjusting means 61.₀Hand subtracted from GO
Output B of stage 58_YSubtraction means for subtracting, 66 is addition means
The output of 62 is the coefficient E of the gain adjusting means control circuit 56._LIn response
Gain adjusting means 67 for adjusting the gain, and 67 of the adding means 63.
The output is the coefficient E of the gain adjusting means control circuit 56._RAccording to
Gain adjusting means for obtaining and adjusting, 68 is an output of the adding means 64
Coefficient E of gain adjusting means control circuit 56_CGain adjustment according to
A gain adjusting means 69 for adjusting the output of the adding means 65.
Coefficient E of the adjusting means control circuit 56_SProfit adjusted according to
The gain adjusting means, 74 corresponds to the output of the sound source direction detecting means 5.
Coefficient F_C, F_S, F_L, F_RFrequency characteristic adjusting means
A control circuit 70 controls the output of the gain adjusting means 66 as a frequency characteristic.
Coefficient F of adjusting means control circuit 74_LFrequency characteristics according to
Frequency characteristic adjusting means for adjustment, 71 is gain adjusting means 67
Of the frequency characteristic adjusting means control circuit 74 as an output of_RTo
Frequency characteristic adjusting means for adjusting the frequency characteristic in accordance with 72
Outputs the output of the gain adjusting means 68 to the frequency characteristic adjusting means control circuit.
Coefficient F of path 74_CFrequency to adjust frequency characteristics according to
Characteristic adjusting means 73 indicates the frequency of the output of the gain adjusting means 69.
Coefficient F of the characteristic adjusting means control circuit 74 _SDepending on the frequency
Frequency characteristic adjusting means for adjusting the
L'signal output terminal for outputting the output of the adjusting means 70, 76
R'signal output for outputting the output of the frequency characteristic adjusting means 71
The terminal 77 outputs the output of the frequency characteristic adjusting means 72.
C'signal output terminal, 78 is an output of the frequency characteristic adjusting means 73.
This is an S'signal output terminal for outputting force. As above
The operation of the configured matrix device 50 will be described.
It

Subtraction means 5 equivalent to a bidirectional microphone
The directional characteristic D _BX (θ) of the output of No. 7 and the directional characteristic D _BY (θ) of the output of the subtraction unit 58 are (Equation 26) and (Equation 27).
It is represented by.

[0073]

[Equation 26]

[0074]

[Equation 27]

FIG. 7A shows the directional characteristic of the output B _X of the subtracting means 57, and FIG. 7B shows the output B _{Y of the} subtracting means 58.
FIG. 7C is a diagram showing the directional characteristic of the omnidirectional microphone 51. FIG. X <0 in FIG. 7 (a)
A broken line in the curve indicating the directional characteristics in the area of (1) and the area of y <0 in FIG. 7 (b) indicates that this area has an opposite phase.

The outputs B _X and B _Y of the subtraction means 57 and 58 are subtracted by the subtraction means 59 and added by the addition means 60. The output O of the omnidirectional microphone 51 is multiplied by E _O in the gain adjusting unit 61 according to the control voltage E _O of the gain adjusting unit control circuit 56, and the subtracting units 57 and 58 and the subtracting unit 59,
The output of the adding means 60 is added by the adding means 62, 63, 64, and subtracted by the subtracting means 65. The gain adjusting means control circuit 56 will be described later. Then, the adding means 62
Is output by the gain adjusting means 66 to the gain adjusting means control circuit 5
It is multiplied by E _L according to the control voltage E _{L of} 6 and output from the output terminal 75 as an output signal L ′. Similarly, addition means 63,
The output of 64 is multiplied by E _R and E _C by gain adjusting means 67 and 68, respectively, and output terminals 7 are output signals R ′ and C ′.
6 and 77 respectively. Further, the output of the subtracting means 65 is multiplied by E _S by the gain adjusting means 69 and output from the output terminal 78 as the output signal S ′.

The relationships between the signals of the bidirectional microphones and the omnidirectional microphones of the matrix device 50 as described above and the respective outputs are expressed by (Equation 28) to (Equation 31).

[0078]

[Equation 28]

[0079]

[Equation 29]

[0080]

[Equation 30]

[0081]

[Equation 31]

The directivity characteristic of the output signal of the matrix device 50 formed as shown in (Equation 28) to (Equation 31) is (Equation 3).
2) to (Equation 35).

[0083]

[Equation 32]

[0084]

[Expression 33]

[0085]

[Equation 34]

[0086]

[Equation 35]

FIG. 8 shows the directional characteristics shown in (Expression 32) to (Expression 35). FIG. 8A shows the directivity D _L ′ of the L ′ signal.
8 (b) is the directivity characteristic D _R ′ of the R ′ signal in FIG.
8C, the directivity characteristic D _C ′ of the C ′ signal is shown in FIG.
8 (d), the directivity D _S ′ of the S ′ signal in FIG.
(Θ) is shown. However, E _O = 1 and E _L , E _R , E _C and E _S
= 1/2.

As can be seen from FIG. 8, the directivity characteristic D _L ′ (θ) of the L ′ signal is in the 135 ° direction, the directivity characteristic D _R ′ (θ) of the R ′ signal is in the 45 ° direction, and the directivity characteristic of the C ′ signal is Directivity D _C ′
(Θ) is in the 90 ° direction, and the directivity characteristic D _S ′ of the S ′ signal
(Θ) has maximum sensitivity in the 270 ° direction.

Next, the gain adjusting means control circuit 56 will be described. The gain adjusting means control circuit 56 adjusts the directivity of the output signal and adjusts the gain of the output signal in order to emphasize and collect the target sound.

The gain adjusting means control circuit 56 receives the output signals D _LR and D _CS of the sound source direction detecting means 5 as inputs, and receives the control signal E.
Outputs _O , E _L , E _R , E _C , and E _S. Control signal E _O is supplied to the gain adjusting means 61 for controlling the directional characteristic of the output signal, the control signal _{E L, E R, E C} , supplied to the E _S each gain adjusting means 66, 67, 68, 69 And is adjusted so as to emphasize the output in the direction of the target sound.

The specific operation of the gain adjusting means control circuit 56 will be described. D _LR and D _CS input from the sound source direction detecting means 5 are as expressed by (Equation 11) and (Equation 12).

First, the control signal E _O for adjusting the gain of the omnidirectional microphone 51 and controlling the directional characteristics of the output signals L ', R', C ', S'will be described. For example, paying attention only when the target sound is in front, when the target sound exists at an angle of ± 15 ° around the maximum sensitivity direction of each output as shown in FIG. 9, the output signals L ′, R ', C',
The direction of the target sound is emphasized by making the directional characteristic of S ′ steep.

[0093] In this embodiment, when the target sound comes from the direction indicated by oblique lines in FIG. 9, E a gain adjustment means control circuit 56 _O
= 1 to E _o = 0.8. (Equation 1
1), (Equation 12) and (Equation 21) to (Equation 25), the relationship between the arrival angle of the target sound and D _LR , D _CS shown in FIG. 9 is shown in (Table 2).

[0094]

[Table 2]

Next, the control signals E _L , E _R , E _C , and E _S for adjusting the gains of the output signals L ', R', C ', and S'to emphasize the target sound direction will be described. Consider when the target sound is ahead. When the target sound arrives from the direction indicated by the diagonal lines in FIG. 10, the gain of the output signals L ', R', C ', S'is adjusted to emphasize the target sound direction.
Table 3 shows the relationship between the arrival direction of the target sound and D _LR , and the correspondence between the control signals E _L , E _R , and E _C at that time. Since the target sound is limited to the front, E _S does not change, and D _{CS at} which other control signals change is in the range of D _CS (θ) <0.

[0096]

[Table 3]

The frequency characteristic adjusting means control circuit 74 and the frequency characteristic adjusting means 70, 71, 72, 73 operate in the same manner as in the first embodiment.

As described above, the present invention uses the outputs of a plurality of unidirectional microphones to detect the direction of the target sound by the sound source direction detecting means, adjusts the gain of the microphone output by the signal control means, and The direction of the target sound can be emphasized by adjusting the characteristics. Furthermore, by using a plurality of unidirectional microphones and omnidirectional microphones and calculating the output with a matrix device, not only the gain adjustment and frequency characteristic adjustment but also the directional characteristic of the output signal can be adjusted. The directionality of the target sound can be further emphasized to collect the sound. In this way, by emphasizing the direction of the target sound to be collected and collecting the sound,
Since the level of the target sound is relatively higher than the unnecessary sound level, the S / N ratio can be improved, and by passing only the low frequency component of the unnecessary sound, the feeling of being wrapped in the sound becomes and The effect that it can be emphasized is obtained.

[0099]

As described above, according to the present invention, the direction of the target sound is detected by the sound source direction detecting means using the outputs of the plurality of unidirectional microphones, and the gain of the microphone output is adjusted by the signal controlling means. Thus, the direction of the target sound can be emphasized. Furthermore, by using a plurality of unidirectional microphones and omnidirectional microphones and calculating the output with a matrix device, not only the gain adjustment but also the directional characteristics of the output signal are adjusted so that the directionality of the target sound is Can be more emphasized and picked up. Further, by passing only the low frequency component of the unnecessary sound, the sound becomes wrapped in the sound and the target sound is emphasized. As described above, by emphasizing the direction of the target sound to be collected and collecting the target sound, the level of the target sound becomes relatively higher than the unnecessary sound level, and the S / N ratio can be improved. By passing only the low-frequency component of the sound, the sound is surrounded by the sound, and as a result, the target sound is emphasized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a sound collecting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a maximum sensitivity direction of the microphone in the first embodiment.

FIG. 3 is a characteristic diagram showing directional characteristics of the microphone according to the first embodiment.

FIG. 4 is a block diagram showing an internal configuration of frequency characteristic adjusting means in the first embodiment.

FIG. 5 is a block diagram showing a configuration of a sound collecting device according to a second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing directional characteristics of a microphone according to the second embodiment.

FIG. 7 is a characteristic diagram showing a directivity characteristic of the output of the subtracting means in the second embodiment.

FIG. 8 is a characteristic diagram showing a directivity characteristic of an output signal of the matrix device according to the second embodiment.

FIG. 9 is an explanatory diagram showing a range of a target sound arrival direction in which directivity characteristic control is performed in the second embodiment.

FIG. 10 is an explanatory diagram showing a range of a target sound arrival direction in which gain adjustment is performed in the second embodiment.

FIG. 11 is a block diagram showing a configuration of a conventional sound collecting device.

FIG. 12 is an explanatory diagram showing a maximum sensitivity direction of a microphone in a conventional sound pickup device.

FIG. 13 is a characteristic diagram showing directional characteristics of a microphone in a conventional sound pickup device.

FIG. 14 is a characteristic diagram showing directivity of an output signal in a conventional sound collecting device.

[Explanation of symbols]

 1 to 4, 52 to 55 Unidirectional microphone 5 Sound source direction detecting means 6 Signal control means 7 to 10 Full wave rectifying circuit 11, 12 ... Logarithmic difference circuit, 13 Threshold switch 14, 15 Bi-time constant circuit 16, 56 Gain Adjusting means control circuit 17,74 Frequency characteristic adjusting means control circuit 18-21, 61, 66-69 Gain adjusting means 22-25, 70-73 Frequency characteristic adjusting means 26-29, 75-78 Output terminal 30 Low pass filter 50 matrix device 51 omnidirectional microphone 57-59,65 subtracting means 60,62-64 adding means

Claims (6)

[Claims] 1. A plurality of unidirectional microphones, a sound source direction detecting means for inputting output signals of the plurality of unidirectional microphones and detecting a direction of a sound source, and an output signal of the sound source direction detecting means. A sound pickup device comprising, as an input, signal control means for controlling output signals of the plurality of unidirectional microphones. 2. The sound pickup device according to claim 1, wherein the signal control means controls gains of output signals of the plurality of unidirectional microphones. 3. The sound collecting device according to claim 1, wherein the signal control means controls gains and frequency characteristics of output signals of the plurality of unidirectional microphones. 4. A plurality of unidirectional microphones, an omnidirectional microphone, a sound source direction detecting means for inputting output signals of the plurality of unidirectional microphones and detecting a direction of a sound source, the sound source direction A sound pickup device comprising: a matrix device that receives the output signal of the detection means as an input, calculates the plurality of unidirectional microphones and the omnidirectional microphone signal, and controls the calculated signals. . 5. The sound collecting device according to claim 4, wherein the matrix device controls a gain of the calculated signal. 6. The matrix device controls a gain and a frequency characteristic of the calculated signal.
The sound collecting device described.