JP2003284179A - Microphone system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stereophonic microphone system employing four non- directional microphones that avoids the directive angle from being restricted to one angle so as to select two directive angles. <P>SOLUTION: Switches 15, 16 for selecting output signals of the four non- directional microphones 11 to 14 are positioned at a pre-stage of directivity composite circuits 17, 18 to change the arrangement of the four non-directional microphones used for composing the directivity so as to permit the selection of two directive angles. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereo microphone device built in a video integrated camera or the like.

[0002]

2. Description of the Related Art In recent years, a stereo microphone has been built into a video-integrated camera or the like, and has been widely used as a means for recording a sound with a sense of presence at the same time as an image.

A conventional stereo microphone will be described below.

A stereo microphone is a microphone in which two unidirectional microphones are arranged such that their directional axes form a constant opening angle, and their respective outputs are left and right two-channel signals. In a stereo microphone built into a video-integrated camera, it is common to combine a unidirectional microphone with a plurality of omnidirectional microphones.

First, a so-called directional synthesis method for obtaining unidirectionality by using a plurality of omnidirectional microphones will be described. FIG. 8 is a schematic view showing a state in which two omnidirectional microphones are arranged in a device such as a video camera. The upper side in the figure shows the front side of the device and the lower side shows the inner side of the device. FIG. 9 is a block diagram showing a configuration in which unidirectionality is synthesized from two omnidirectional microphones, and FIGS. 10A to 10C are characteristic diagrams when a sound source is located on the 83a side of the directional axis of the microphones. , (D) to (f) are characteristic diagrams when the sound source is located on the 83b side of the directional axis.

In FIG. 8 and FIG. 9, 84 is a sound source,
Reference numeral 4a indicates a sound source located on the front side of the device, and 84b indicates a sound source located on the opposite side of the device. Reference numerals 81 and 82 denote first and second microphones formed of omnidirectional microphones, respectively. The first microphone 81 is arranged on the front side of the device, and the second microphone 82 is arranged on the inner side of the device. Reference numeral 83 indicates a directional axis formed by the first and second microphones 81 and 82, and the upper tip 83a has a directional angle of 0 ° and the lower tip 83b has a directional angle of 180 ° as shown in the drawing. 85 is a phase shifter for shifting the phase of the output sound of the second microphone 82, and 86.
Is an adder for synthesizing the output voice of the first microphone 81 and the output voice of the phase shifter 85, and the output voice of the phase shifter 85 is synthesized with its phase being opposite phase. In FIG. 10, a solid line characteristic of 91 is an audio signal picked up by the first microphone 81, and a dotted line characteristic of 92 is a second microphone 82.
It is a voice signal picked up by.

The operation of directional synthesis using the omnidirectional microphone configured as described above will be described below.

First, in order to obtain unidirectionality by using two omnidirectional microphones, first and second microphones 81 and 82 are arranged as shown in FIG. Specifically, the first microphone 81 is arranged on the front side of the device, and the second microphone 82 is arranged on the inner side of the device. Then, the directional axis 83 is generated on the line connecting the centers of the first and second microphones 81 and 82. In the illustrated case, the upper end of the directional axis 83 corresponds to the end side of the device.

In this structure, the position of the sound source 84 is 84
When the angle θ with respect to the directional axis 83 is at a position of 0 ° as shown in a, the phase relationship between the audio signals of the first and second microphones 81 and 82 is the characteristics 91 and 92 of FIG.
become that way. That is, since the characteristic 92 of the audio signal picked up by the second microphone 82 is located farther from the sound source 84 than the first microphone 81,
The phase is delayed by t1. The voice signal picked up by the second microphone 82 is input to the phase shifter 85, and its phase is t
It is moved two times and becomes as shown in FIG. Next adder 8
6, the audio signal from the phase shifter 85 is added in the opposite phase to the audio signal from the first microphone 81, and FIG.
As shown in, the audio signal whose amplitude has been amplified is output.

On the other hand, when the sound source 84 is at a position where the angle θ is 180 ° with respect to the tip 83a of the directional axis 83 as shown at 84b, the input voice becomes as shown in FIG. 10 (d). In other words, since the positional relationship is opposite to that when the angle θ is 0 °,
The phase of the input voice of the second microphone 82 advances by t1. Next, the phase shifter 85 delays the phase of the audio signal of the second microphone 82 by t2, so that the characteristics 91 and 92 become substantially in phase, as shown in FIG. Next, the adder 86 converts the audio signal from the first microphone 81 into
The audio signals from the phase shifter 85 are added in opposite phase, and
As shown in (f), the output has a value close to zero.

Thus, when the sound source 84 is on the front side of the device as shown at 84a, an audio signal is output as shown in FIG. 10C, and when it is on the opposite side of the device, as shown in FIG.
As shown in 0 (f), the audio signal has a minute value close to 0. Therefore, it is possible to obtain a unidirectional microphone in the direction of the tip 83a of the directional axis 83.

FIG. 7 shows an example of a stereo microphone using four omnidirectional microphones.

In FIG. 7, 71, 72, 73 and 74 are omnidirectional microphones. 75 and 76 are directivity synthesis circuits. The omnidirectional microphones 71 and 73 and the omnidirectional microphones 72 and 74 are arranged so as to form a diagonal of a rectangle.

The operation of the conventional stereo microphone configured as described above will be described below.

First, the voices picked up by the omnidirectional microphones 71 and 73 are input to the directivity synthesis circuit 75, and the voices having the unidirectionality based on the above-described directivity synthesis method are Lch voices. Is output. On the other hand, the voice picked up by the omnidirectional microphones 72 and 74 is input to the directivity synthesis circuit 76, and the voice having the unidirectionality is output as the Rch voice based on the above-described directivity synthesis method. .

As a result, the angle θ1 formed by the left and right directional axes
(Hereinafter, referred to as "directivity angle") is an intersection angle of diagonal lines as shown in FIG. In the conventional case, this directivity angle is about 120.
It is set to °, and good stereo sound can be picked up when the sound source is located in front of the camera.

[0017]

However, in the above-mentioned conventional structure, the pattern having the directional angle as shown in FIG. 3 can be obtained even though the four omnidirectional microphones are used.
With the directional angle as shown in FIG. 3, sound can be picked up well for a sound source located in front of the camera, but when the sound source covers a wide range (such as when shooting scenery such as the sea or sports in a stadium, etc.). In shooting competitions, etc.), there is a problem in that the directivity angle is insufficient, and sound cannot be picked up to obtain a realistic sound spread.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a microphone device capable of selecting two directional angles by using four omnidirectional microphones.

[0019]

In order to achieve this object, a microphone device of the present invention comprises first and second omnidirectional microphones arranged at adjacent vertices of a rectangle.
A third diagonally arranged third omnidirectional microphone
Omnidirectional microphone, a fourth omnidirectional microphone diagonally arranged to the second omnidirectional microphone, an output signal of the second omnidirectional microphone, and the third omnidirectional microphone. Of the output signal of the first omnidirectional microphone and the output signal of the fourth omnidirectional microphone in conjunction with the first selection means for switching the output signal of A selection means, a first directivity combining means for generating directivity from an output signal of the first omnidirectional microphone and an output signal of the first selection means, and the second omnidirectional microphone. It has a configuration including second directivity combining means for generating directivity from the output signal and the output signal of the second selecting means.

With this configuration, a microphone device having two directivity angles can be obtained.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises a pair of first and second omnidirectional microphones arranged at adjacent vertices of a rectangle, and the first omnidirectional microphone. A third omnidirectional microphone placed in the corner,
A fourth diagonally arranged fourth omnidirectional microphone
Omnidirectional microphone, first selecting means for switching between the output signal of the second omnidirectional microphone and the output signal of the third omnidirectional microphone, and the first selecting means in conjunction with the first selecting means. A second selecting means for switching between an output signal of the first omnidirectional microphone and an output signal of the fourth omnidirectional microphone; an output signal of the first omnidirectional microphone and the first selecting means. First directivity synthesizing means for generating directivity from the output signal, and second directivity for generating directivity from the output signal of the second omnidirectional microphone and the output signal of the second selecting means. The present invention is characterized in that the directivity angle can be selected from two angles of 180 degrees and a crossing angle of diagonal lines.

According to a second aspect of the present invention, the directivity synthesizing means includes phase shifting means capable of changing the amount of phase shifting.
It has the effect of optimizing the amount of phase shift of the phase shifter of the directional synthesis circuit in accordance with the distance between the two omnidirectional microphones used for directional synthesis.

According to a third aspect of the present invention, there is provided a first structure in which two diagonal lines and an upper base are arranged at both ends of an upper base of an isosceles trapezoid having the same length.
And a second omnidirectional microphone, a third omnidirectional microphone arranged diagonally to the first omnidirectional microphone, and a fourth omnidirectional microphone arranged diagonally to the second omnidirectional microphone. An omnidirectional microphone, a first selecting means for switching between an output signal of the second omnidirectional microphone and an output signal of the third omnidirectional microphone, and the first selecting means in conjunction with the first selecting means. A second selecting means for switching between an output signal of the first omnidirectional microphone and an output signal of the fourth omnidirectional microphone; and an output signal of the first omnidirectional microphone and the first selecting means. First directivity synthesizing means for generating directivity from the output signal, and second directivity for generating directivity from the output signal of the second omnidirectional microphone and the output signal of the second selecting means. Sex hand It is characterized in that the directivity angle can be selected from two angles, that is, a diagonal intersection angle and 180 degrees, and that the distance between the two omnidirectional microphones used for directivity synthesis is always constant. Since the phase shift amount of the phase shifter of the sex combining circuit is always the same, there is an effect that it is not necessary to change the setting of the phase shift amount.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a microphone device according to Embodiment 1 of the present invention.
Is a schematic diagram when the directivity angle is about 120 °, FIG. 4 is a schematic diagram when the directivity angle is about 180 °, and the arrows in FIGS. 3 and 4 indicate the directivity axis.

In FIG. 1, 11 and 12, 13, 1
Reference numeral 4 denotes first to fourth omnidirectional microphones, which are arranged so as to be located at the vertices of a rectangle as shown in the drawing, and the first and second microphones 11 and 12 are arranged on the front side of the camera. Reference numerals 15 and 16 denote first and second switches which are first and second selection means, and the first switch 15
Switches the second and third omnidirectional microphones 12 and 13 and connects them to a first phase shifter 17a, which will be described later.
Switch 16 switches the first and fourth omnidirectional microphones 11 and 14 to switch a second phase shifter 18a described later.
Connected to. Reference numerals 17a and 18a denote first and second phase shifters, which are first and second phase shift means, respectively.
And the voices from the second switches 15 and 16 are moved by a predetermined phase. Reference numerals 17b and 18b denote first and second adders which are first and second adding means, and are the first adder 17
b is the sound from the first omnidirectional microphone 11 and the first
Of the opposite phase voice from the phase shifter 17a. Further, the second adder 18b is used for the second omnidirectional microphone 12
From the second phase shifter 18a is synthesized. The first and second adders 17b and 1b
8b may have a configuration other than an adder, and may be a subtractor if the signals from the first and second omnidirectional microphones 11 and 12 are combined in antiphase. Reference numeral 17 is a first directivity combining circuit which is a first directivity combining means composed of a first phase shifter 17a and a first adder 17b, and 18
Is a second directivity synthesizing circuit which is a second directivity synthesizing means composed of the second phase shifter 18a and the second adder 18b.

The operation of the microphone device configured as described above will be described with reference to FIGS. 1, 3, and 4.

First, the switch 15 is switched to the A side to select the third omnidirectional microphone 13, and the switch 16
Is switched to the A side and the fourth omnidirectional microphone 14 is selected, the sound picked up by the third omnidirectional microphone 13 is input to the first phase shifter 17a, and based on the above-described directivity synthesis method. After the phase is shifted, the first adder 1
In 7b, it is synthesized with the voice from the first omnidirectional microphone 11. Further, the voice picked up by the fourth omnidirectional microphone 14 is input to the second phase shifter 18a, and the phase thereof is shifted based on the above-described directivity synthesis method, and then the second adder 18b outputs it. It is synthesized with the voice from the two omnidirectional microphones 12. At this time, the respective directional axes are as shown in FIG. 3, and the directional angles are the angle of intersection of the diagonal lines (about 120 °) as in the conventional stereo microphone. With this directivity angle, sound can be favorably picked up by a sound source located in the front direction of the camera.

Next, the switch 15 is switched to the B side to select the second omnidirectional microphone 12, and the switch 16
Is switched to the B side and the first omnidirectional microphone 11 is selected, the sound picked up by the second omnidirectional microphone 12 is input to the first phase shifter 17a, and based on the above-described directivity synthesis method. After the phase is shifted, the first adder 1
In 7b, it is synthesized with the voice from the first omnidirectional microphone 11. Further, the voice picked up by the first omnidirectional microphone 11 is input to the second phase shifter 18a, and the phase thereof is shifted based on the above-described directivity synthesis method, and then the second adder 18b outputs it. It is synthesized with the voice from the two omnidirectional microphones 12. At this time, the respective directional axes are as shown in FIG. 4, and the directional angles are about 180 degrees. At this angle,
A sound source located around the camera (wide range) can be picked up well.

Here, in order to switch the first and second switches 15 and 16, a mechanical switch such as a slide switch may be provided in the camera body, and a setting menu standardly provided in recent video cameras. May be switched by software. In any case, the user can set it arbitrarily.

As described above, according to this embodiment, the first
And by switching the second switches 15 and 16,
Since the directional axis shown in FIG. 3 and the directional axis shown in FIG. 4 can be switched, a sound source located in front of the camera and a sound source over a wide range around the camera can be picked up well.

In this embodiment, the amount of phase shift in the first and second phase shifters 17a and 18a is the same between the case of FIG. 3 and the case of FIG. The distance between the two omnidirectional microphones used for directional synthesis is different between the case of 4 and the case of 4 (L4> L5).
Therefore, if the first and second phase shifters 17a and 18a switch the amount of phase shift corresponding to the intervals L4 and L5, respectively, better unidirectionality can be obtained. That is, since the distances of the two omnidirectional microphones are different between the intervals L4 and L5, the phase difference t1 shown in FIGS. 10A and 10D described above is different. Therefore, the amount of the phase shift amount (t2 in FIGS. 10B and 10E) in the phase shifter may be changed according to this phase difference.

(Second Embodiment) FIG. 2 is a block diagram showing a configuration of a microphone device according to a second embodiment of the present invention. In FIG. 2, 21 and 22, 23, and 24 are the first
~ Fourth omnidirectional microphone, 25 and 26 are first and second switches, and 27 and 28 are first and second directivity combining circuits, which are omitted in the drawing but moved to the inside similarly to FIG. It has a phaser and an adder. The above is the same as the configuration of FIG. 1 (reference numerals are different). The difference from the configuration of FIG. 1 is that the first to fourth omnidirectional microphones 21, 22, 2
Arrange 3, 24 to form a quadrangle as shown,
And first and third omnidirectional microphones 21 and 23
Diagonal line L3, the diagonal line L2 of the second and fourth omnidirectional microphones 22 and 24, and the diagonal line L1 of the first and second omnidirectional microphones 21 and 22 all have the same length (L1 = L2 = L3) is a point placed at the apex of an isosceles trapezoid having a diagonal line.

The operation of the microphone device of the present embodiment configured as described above will be described with reference to FIGS. 2, 5, and 6.

Similar to the configuration of FIG. 1, the first and second switches 25 and 26 are switched to select the directivity angle of FIG. 5 or 6. At this time, 2 used for the directional synthesis shown in FIG.
Since the interval (L2, L3) between the two omnidirectional microphones is the same as the interval L1 between the two omnidirectional microphones shown in FIG. 6, the first and second directivity combining circuits 27 and 2 are provided.
The amount of phase shift of the phase shifter (not shown) in 8 may have the same characteristics.

As described above, according to the present embodiment, the four omnidirectional microphones are arranged at the apexes of the isosceles trapezoid and the switch for switching the omnidirectional microphones used for the directional synthesis is provided. It is possible to select two directivity angles without changing the setting of the amount of phase shift in the first and second directivity combining circuits 27 and 28.

[0037]

As described above, according to the present invention, in the stereo microphone device using the four omnidirectional microphones, two directivity angles are selectable, so that the sound source located in front of the camera is mainly used. Also in stereo recording, when the sound source is over a wide range (such as scenery shooting of the sea,
Stereo recording, which mainly focuses on the spread of the sound when shooting sports competitions at stadiums, etc., also has the excellent effect of being able to pick up the sound satisfactorily.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a configuration of a microphone device according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a microphone arrangement and a directional axis of the microphone device according to the first embodiment of the present invention and the prior art.

FIG. 4 is a schematic diagram showing a microphone arrangement and a directional axis of the microphone device according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a microphone arrangement and a directional axis of the microphone device according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram showing a microphone arrangement and a directional axis of a microphone device according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional microphone device.

FIG. 8 is a schematic diagram showing an arrangement configuration of omnidirectional microphones for explaining a directional synthesis method.

FIG. 9 is a block diagram showing a configuration of directivity synthesizing means.

FIG. 10 is a characteristic diagram of a sound signal when the sound source is 0 ° and 180 ° with respect to the directional axis.

[Explanation of symbols]

11,21 1st omnidirectional microphone 12,22 Second omnidirectional microphone 13,23 Third Omnidirectional Microphone 14, 24 Fourth omnidirectional microphone 15,25 First switch 16,26 Second switch 17, 27 First directivity synthesis circuit 18, 28 Second directivity synthesis circuit 17a First phase shifter 18a Second phase shifter 17b First adder 18b Second adder

Claims (3)

[Claims] 1. A first device arranged at adjacent vertices of a rectangle.
And a second omnidirectional microphone, a third omnidirectional microphone arranged diagonally to the first omnidirectional microphone, and a fourth omnidirectional microphone arranged diagonally to the second omnidirectional microphone. An omnidirectional microphone, a first selecting means for switching between an output signal of the second omnidirectional microphone and an output signal of the third omnidirectional microphone, and the first selecting means in conjunction with the first selecting means. Second selection means for switching between the output signal of the first omnidirectional microphone and the output signal of the fourth omnidirectional microphone; the output signal of the first omnidirectional microphone and the output of the first selection means A first directivity synthesizing means for generating directivity from the signal; and a second directivity generating means for generating directivity from the output signal of the second omnidirectional microphone and the output signal of the second selecting means.
And a directivity synthesizing means for the microphone device. 2. The microphone device according to claim 1, wherein the directivity synthesizing means includes a phase shifting means capable of changing a phase shifting amount. 3. A first and a second omnidirectional microphones arranged at both ends of an upper leg of an isosceles trapezoid having two diagonals and an upper bottom having the same length, and a diagonal of the first omnidirectional microphone. A third omnidirectional microphone arranged in a diagonal direction, a fourth omnidirectional microphone arranged diagonally to the second omnidirectional microphone, an output signal of the second omnidirectional microphone and the third omnidirectional microphone. Selecting means for switching the output signal of the omnidirectional microphone, and the output signal of the first omnidirectional microphone and the output signal of the fourth omnidirectional microphone in cooperation with the first selecting means. And a second directivity synthesizing means for generating directivity from an output signal of the first omnidirectional microphone and an output signal of the first selection means. Omnidirectional microphone output A microphone device comprising: a second directivity synthesizing means for generating directivity from a force signal and an output signal of the second selecting means.