JP2000350281A - Microphone device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microphone device which can pick up a sound rich in presence and is advantageous in making equipment compact and inexpensive. SOLUTION: This device is equipped with switch means 21a and 21b which selects the output signals of 1st or 3rd microphone elements, a delay means 17 which delays the output signal of the switch means 21b, a composing means 15 which puts together the output signals of the switch means 21a and delay means 17, a selecting means 22 which selects the states of the switch means 21a and 21b, a delay means 18 which delays the output signal of a 4th microphone element, and a composing means 16 which puts together the output signals of the 2nd microphone element and the delay means 18; and the output signal of the composing means 15 is used for the 1st channel signal of a stereophonic signal and the output signal of the composing means 16 is used for the 2nd channel signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microphone device mounted on, for example, a video camera or the like.

[0002]

2. Description of the Related Art Conventionally, in stereo recording with a microphone built in a video camera, a directional characteristic of a microphone element is set for the purpose of recording a sound source in front. Therefore, as shown in FIG. 10, a method of arranging two unidirectional microphone elements 100a and 100b at a certain angle has been adopted. This increases sensitivity to sound from the front direction (subject direction), works favorably for the sound of the subject moving to the lens of the video camera, and conversely, sensitivity to sound from the back direction opposite to the subject. And the video camera has advantages such as no noise. FIG. 11 shows polar patterns of both the left and right channels in this case, and FIG. 12 shows polar patterns of only the right channel.

[0003]

However, in the above-described conventional example, since the sensitivity to the sound in the back direction is low as described above, the positional relationship between the photographer and the microphone is shown in FIG. In such a state, there is a problem in that a so-called narration sound in which the photographer speaks about a photographing situation or the like is difficult to enter, and depending on the video, a sense of reality may be lacking.

FIG. 13 is a side view showing a shooting state of the video camera, and FIG. 14 is a plan view showing a shooting state of the video camera. 13 and 14, 1301 is a video camera, 1302 is a lens, 1303 is a microphone, 1304 is a monitor screen, 1305 is a photographer,
Reference numeral 1306 denotes a photographer's mouth.

In order to solve the above problem, another microphone is additionally arranged in a portion of the video camera 1301 located near the mouth 1306 of the photographer 1305 so that only the sound of the narration can be recorded well. However, this method is disadvantageous in reducing the size and cost of the video camera due to the increase in the volume of a microphone to be added and the number of microphone amplifiers.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to realize a recording with a rich sense of reality, to reduce the size of the equipment and to reduce the cost. It is an object of the present invention to provide a microphone device that is advantageous in achieving this.

[0007]

According to a first aspect of the present invention, there is provided a microphone device comprising:
Third and fourth four omnidirectional microphone elements,
The positional relationship between the four microphone elements is an angle between a straight line connecting the first microphone element and the third microphone element and a straight line connecting the second microphone element and the fourth microphone element. And a first switching means for switching between an output signal of the first microphone element and an output signal of the third microphone element, and an output signal of the first microphone element. And second switching means for switching the output signal of the third microphone element; first delay means for delaying the output signal of the second switching means; and output signals of the first switching means and the second switching means. A first synthesizing means for synthesizing an output signal of the first delay means, and a switching state of the first switching means and the second switching means. And a second delay unit that delays the output signal of the fourth microphone element, and a second unit that combines the output signal of the second microphone element and the output signal of the second delay unit. And an output signal of the first synthesizing means as a first channel signal of a stereo signal, and an output signal of the second synthesizing means as a second channel signal of a stereo signal. It is characterized by.

Further, in order to achieve the above object, a second aspect is provided.
The described microphone device comprises first, second, third, fourth
And the positional relationship between the four microphone elements is such that a straight line connecting the first microphone element and the third microphone element, the second microphone element, and the In a microphone device arranged at an angle with a straight line connecting to a fourth microphone element, a first delay means for delaying an output signal of the third microphone element;
Second delay means for delaying the output signal of the first microphone element, switching means for switching between the output signal of the first delay means and the output signal of the second delay means, and the output of the first microphone element First combining means for combining the signal and the output signal of the switching means, third delay means for delaying the output signal of the fourth microphone element, and the output signal of the second microphone element and the second combining means. A second synthesizing means for synthesizing an output signal of the third delay means, and a selecting means for selecting a switching state of the switching means, wherein the output signal of the first synthesizing means is converted to a first stereo signal. A channel signal, and an output signal of the second synthesizing means is a second channel signal of a stereo signal.

[0009] In order to achieve the above object, a third aspect is provided.
The described microphone device comprises first, second, third, fourth
And the positional relationship between the four microphone elements is such that a straight line connecting the first microphone element and the third microphone element, the second microphone element, and the In a microphone device arranged at an angle with a straight line connecting to a fourth microphone element, first delay means for delaying an output signal of the third microphone element;
First combining means for combining the output signal of the microphone element and the output signal of the first delay means, and switching for switching between the output signal of the first combining means and the output signal of the third microphone element. Means, selection means for selecting a cut-off state of the switching means, second delay means for delaying an output signal of the fourth microphone element, output signal of the second microphone element, and the second delay Second combining means for combining the output signal of the switching means with the output signal of the switching means.
And the output signal of the second synthesizing means is a second channel signal of a stereo signal.

[0010] Further, in order to achieve the above object, a fourth aspect is provided.
The microphone device according to the first aspect of the present invention is the microphone device according to the first aspect, wherein a delay characteristic of the first delay unit and a delay characteristic of the second delay unit are different from each other.

[0011] In order to achieve the above object, the present invention provides a fifth aspect.
The microphone device according to any one of claims 1 to 3, wherein the first delay unit and the second delay unit are low-pass filters.

[0012] In order to achieve the above object, the present invention provides a semiconductor device comprising:
The microphone device according to any one of claims 1 to 3, wherein the first delay unit and the second delay unit are transfer units.

[0013] In order to achieve the above object, the present invention is directed to claim 7.
The microphone device according to the present invention is characterized in that, in the microphone device according to any one of claims 1 to 3, the first delay unit and the second delay unit perform delay processing by digital signal processing.

[0014]

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

(First Embodiment) First, a first embodiment of the present invention will be described.
An embodiment will be described with reference to FIGS.

FIG. 1 is a diagram showing the arrangement of microphone elements in the microphone device according to the present embodiment. In the figure, reference numerals 1, 2, 3, and 4 denote omnidirectional microphone elements, a microphone element 1 is a right front part in a sound source direction (arrow direction in the figure), a microphone element 2 is a left front part in a sound source direction, The microphone element 3 is disposed on the left rear side toward the sound source direction, and the microphone element 4 is disposed on the right rear side toward the sound source direction. A straight line l1 connecting the microphone element 1 and the microphone element 3 and a straight line l2 connecting the microphone element 2 and the microphone element 4
Is defined as θ. The distance between the microphone element 1 and the microphone element 3 and the distance between the microphone element 2 and the microphone element 4 are L.

FIG. 2 is a block diagram showing a configuration of a correction circuit in the microphone device according to the present embodiment. In the figure, 11 is an input terminal for inputting an output signal of the microphone element 1, 12 is an input terminal for inputting an output signal of the microphone element 2, and 13 is an input terminal for inputting an output signal of the microphone element 3. Terminal, 1
Reference numeral 4 denotes an input terminal for inputting an output signal of the microphone element 4.

15 is a first synthesizing means, 16 is a second synthesizing means, 17 is a first delay means for giving a first delay characteristic,
Reference numeral 18 denotes a second delay unit that provides a second delay characteristic, 19 denotes an output terminal of the first synthesizing unit 15, 20 denotes an output terminal of the second synthesizing unit 16, and 21 denotes a switching unit. It has a (first switching means) 21a and a second switching unit (second switching means) 21b. First
The switching unit 21a switches the input signal of the first synthesizing unit 15 between the input signal from the input terminal 11 and the input signal from the input terminal 13. Also, the second switching unit 21b
Switches the input signal of the first delay means 17 between the input signal from the input terminal 11 and the input signal from the input terminal 13. The first switching unit 21a controls the first combining unit 15
Is switched so that the input signal from the input terminal 11 becomes the input signal from the input terminal 11, the first switching unit 21b causes the input signal of the first delay unit 17 to become the input signal from the input terminal 13. Switch. Reference numeral 22 denotes a selection means (switch) for selecting the switching state of the switching means 21. The input signal of the first synthesizing means 15 is on the input terminal 11 side, and the input signal of the first delay means 17 is on the input terminal. The state where the input signal of the first synthesizing means 15 is on the input terminal 13 side and the state where the input signal of the first delay means 17 is on the input terminal 11 side are the narration state. I do.

First delay means 17 and second delay means 1
As 8, the case where a low-pass filter is used and the selection unit 22 is in the standard state will be described.

The first synthesizing means 15 includes a switching means 21
The second synthesizing means 16 subtracts the output signal of the second delay means 18 from the input signal input from the input terminal 12 by performing a synthesizing process of subtracting the output signal of the first delay means 17 from the output signal of the first delay means 17. Perform synthesis processing.

The distance between the microphone element 1 and the microphone element 3 in FIG. 1 is i, and the sound source is a sine wave sinω
The output signals of the microphone elements 1 and 3 when t is input are as follows.

The output signal a of the microphone element 1 is given by the following equation (1).

A = sin ωt (1) The output signal b of the microphone element 3 is given by the following equation (2), where t1 represents a time difference at a distance i between the microphone element 1 and the microphone element 3.

B = sin (ωt + t1) (2) Since a low-pass filter is used as the first delay means 17 and the second delay means 18, if the gain is K and the phase characteristic is ψ, the first The output signal α of the combining means 15 is given by the following equation (3).

Α = sin ωt + K (sin ωt + t1 + ψ + π) (3) Further, the gain K of the low-pass filter given by the transfer function N / 1 + Ts is given by the following equation (4).

K = 20 log [N / {1+ (ωT) ² }] (4) Further, the phase characteristic ψ is given by the following equation (5).

Ψ = −arctan ωT (5) When these are substituted, α is given by the following equation (6).

Α = √ (A ² + B ² ) sin (ωt + arctanB / A) (6) where A = 1 + Kcos (t1 + ψ + π) B = Ksin (t1 + ψ + π) Is i = 15 (mm) The passband gain N of the low-pass filter is N = 1 The time constant T of the low-pass filter is T = 3E- ⁵ , and the polar pattern obtained by changing the incident angle of the sound source from 0 deg to 360 deg Fig. 4 shows the polar pattern of only the right channel as a result of computer simulation.
Shown in As can be seen from the figure, the characteristics of the microphone formed by the pair of the microphone element 1 and the microphone element 3 show the same characteristics as the unidirectionality. Similarly,
The characteristics of the microphone formed by the pair of the microphone element 2 and the microphone element 4 show the same characteristics as the unidirectionality, and the straight line l1 connecting the microphone element 1 and the microphone element 3, the microphone element 2 and the microphone element 4
A stereo microphone arranged at an angle .theta. Formed by a straight line l2 connecting the right and left lines can be realized, and the left and right combined polar patterns are shown in FIG.

Next, the case where the selecting means 22 is in the narration state will be described. This state is switched between the microphone element 1 and the microphone element 3 by the switching means 21.
When the same processing is performed, the characteristics are in a form in which the polar pattern of the above result is inverted. This is the photographer 13 of the straight line l1 in FIGS.
This means that a unidirectional microphone with the mouth direction 05 facing forward is formed. FIG. 5 shows a polar pattern of only the right channel in this case.

As described in detail above, according to the microphone device of the present embodiment, of the output signals of the four microphone elements, the output signals of the first microphone element and the second microphone element are processed. A first unidirectional microphone is formed, and output signals of the third microphone element and the fourth microphone element are processed to form a second unidirectional microphone. As a result, the stereo feeling (realism) is expressed by the angle of the directivity axis formed by the straight line formed by the first microphone element and the second microphone element and the straight line formed by the third microphone element and the fourth microphone element. Becomes Then, the first unidirectional microphone has an action of switching the front direction, and switches to a characteristic in which the mouth of the photographer in the back direction of the video camera is directed to the front, so that narration is very advantageous, and furthermore, Sound can be collected while removing the sound, thereby enabling recording with emphasis on sound collection characteristics.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS. 6 and 7. FIG.

The arrangement of the microphone elements in the microphone device according to the present embodiment is the same as that of the first embodiment shown in FIG. 1, and therefore will be described with reference to FIG.

FIG. 6 is a block diagram showing a configuration of a correction circuit in the microphone device according to the present embodiment. In FIG. 6, the same parts as those in FIG. 2 of the first embodiment are denoted by the same reference numerals. It is attached.

FIG. 6 differs from FIG. 2 in that a third delay means 23 for providing a third delay characteristic is added to the configuration of FIG. 2 and a switching means 24 is provided instead of the switching means 21 of FIG. That is.

The third delay means 23 is connected to the input terminal 13 and the switching means 24. The switching means 24
The first delay unit 17, the third delay unit 23, and the first combining unit 15 are connected to each other. Switching means 24
Switches between a state in which an input signal to the first synthesizing means 15 becomes an output signal of the first delay means 17 and a state in which it becomes an output signal of the third delay means 23. 22. Switching means 2
4, the state where the input signal to the first synthesizing means 15 is switched to the output signal of the first delay means 17 is a standard state, and the state where the output signal of the third delay means 23 is switched is a narration state. And

The standard state is the same as the standard state in the above-described first embodiment, and the characteristics of the microphone are as shown in FIGS.

Next, the narration state will be described.

In the narration state, the output signal of the microphone element 3 connected to the input terminal 13 is transmitted from the third delay unit 23 to the first synthesizing unit 1 via the switching unit 24.
The state has been switched to the state of inputting to 5. Similar to the first embodiment described above as a third delay means 23, in Figure 7 the computer simulation results in the case of setting the time constant T of the low-pass filter T = 1E ⁷ in the case of using a low-pass filter Show. As can be seen from the figure, the characteristic is switched to a characteristic in which the sensitivity of the straight line l1 in FIGS.

As described in detail above, according to the microphone device of the present embodiment, of the output signals of the four microphone elements, the output signals of the first microphone element and the second microphone element are processed. A first unidirectional microphone is formed, and output signals of the third microphone element and the fourth microphone element are processed to form a second unidirectional microphone. As a result, the stereo feeling (realism) is expressed by the angle of the directivity axis formed by the straight line formed by the first microphone element and the second microphone element and the straight line formed by the third microphone element and the fourth microphone element. Becomes And it has the effect of changing the directional characteristics of the first unidirectional microphone, and enables recording with increased sensitivity near the photographer's mouth in the back direction of the video camera.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS.

The arrangement of the microphone elements in the microphone device according to the present embodiment is the same as that in FIG. 1 of the first embodiment, and therefore will be described with reference to FIG.

FIG. 8 is a block diagram showing a configuration of a correction circuit in the microphone device according to the present embodiment. In FIG. 8, the same reference numerals as those in FIG. 2 of the above-described first embodiment denote the same parts. It is attached.

FIG. 8 differs from FIG. 2 in that a switching means 25 is provided in place of the switching means 21 in FIG.

The switching means 25 is connected to the input terminal 13 and the first
Output unit and output terminal 19 of the synthesizing means 15 and selecting means 22
And connected to. The switching means 25 includes an input terminal 1
3 is switched between a state in which the output signal of the microphone element 3 input to the input terminal 3 is input to the output terminal 19 and a state in which the signal output from the first synthesizing means 15 is input to the output terminal 19. Selected by means 22.

The first combining means 1 is switched by the switching means 25.
The state where the signal output from the microphone element 3 is switched so as to be input to the output terminal 19 is referred to as a standard state.
The state where the input is switched to is input is referred to as a narration state.

The standard state is the same as the standard state in the first embodiment described above, and the characteristics of the microphone are as shown in FIGS.

Next, the narration state will be described.

In the narration state, the output signal of the microphone element 3 connected to the input terminal 13 is directly input to the output terminal 19. Microphone element 3
Is an omnidirectional microphone element, so that it exhibits uniform sensitivity characteristics over the entire circumference and can increase the sensitivity in the rear direction of the video camera, which has been attenuated in the standard state.

FIG. 9 shows the characteristics of the microphone device according to the present embodiment.

As described in detail above, according to the microphone device of the present embodiment, the output signals of the first microphone element and the second microphone element among the output signals of the four microphone elements are processed. A first unidirectional microphone is formed, and output signals of the third microphone element and the fourth microphone element are processed to form a second unidirectional microphone. As a result, the stereo feeling (realism) is expressed by the angle of the directivity axis formed by the straight line formed by the first microphone element and the second microphone element and the straight line formed by the third microphone element and the fourth microphone element. Becomes Then, it has an effect of returning one of the four microphone elements to the characteristics of the omnidirectional microphone element, and enables recording with increased sensitivity near the photographer's mouth in the back direction of the video camera. Compared with the first and second embodiments described above, it is possible to increase the sensitivity near the mouth of the photographer in the back direction of the video camera with a very inexpensive configuration, which is effective in reducing the cost of the device. is there.

[0051]

As described above in detail, according to the microphone device of the present invention, the stereo microphone required for normal recording is used as it is, and the sensitivity characteristic is changed at the time of narration recording, so that the narration of the photographer located behind can be obtained. Can be easily picked up, and recording with a sense of reality can be achieved. Further, since the present invention can be realized without adding a new microphone element, the cost increases little and the volume for the microphone does not increase, which is effective in reducing the cost and size of the device.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement configuration of microphone elements in a microphone device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a correction circuit in the microphone device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a polar pattern in a standard state in the microphone device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a polar pattern in a standard state in the microphone device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a polar pattern in a narration state in the microphone device according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a correction circuit in a microphone device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a polar pattern in a narration state in a microphone device according to a second embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a correction circuit in a microphone device according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a polar pattern in a narration state in a microphone device according to a third embodiment of the present invention.

FIG. 10 is a diagram showing an arrangement configuration of microphone elements in a conventional microphone device.

FIG. 11 is a diagram showing a polar pattern in a narration state in a conventional microphone device.

FIG. 12 is a diagram showing a polar pattern in a narration state in a conventional microphone device.

FIG. 13 is a side view showing a relationship between a video camera equipped with a microphone device and a photographer.

FIG. 14 is a plan view showing a relationship between a video camera equipped with a microphone device and a photographer.

[Explanation of symbols]

 1 microphone element 2 microphone element 3 microphone element 4 microphone element 11 input terminal 12 input terminal 13 input terminal 14 input terminal. Reference Signs List 15 first combining means 16 second combining means 17 first delay means 18 second delay means 19 output terminal 20 output terminal 21 switching means 21a first switching unit (first switching means) 21b second Switching unit (second switching unit) 22 Selection unit (switching switch) 23 Third delay unit 24 Switching unit 25 Switching unit 1301 Video camera 1302 Lens 1303 Microphone 1304 Monitor screen 1305 Photographer 1306 Photographer's mouth

Claims (7)

[Claims] A first microphone element that is connected to the first microphone element and the third microphone element, the first microphone element and the third microphone element having a positional relationship between the first microphone element and the third microphone element; And a straight line connecting the second microphone element and the fourth microphone element, the output signal of the first microphone element being arranged at an angle. First switching means for switching between an output signal of the third microphone element and an output signal of the third microphone element; second switching means for switching between an output signal of the first microphone element and an output signal of the third microphone element; A first delay means for delaying an output signal of the second switching means;
First combining means for combining the output signal of the switching means and the output signal of the first delay means, selecting means for selecting a switching state of the first switching means and the second switching means, A second delay unit for delaying an output signal of the fourth microphone element; and a second combining unit for combining an output signal of the second microphone element and an output signal of the second delay unit. A microphone device wherein the output signal of the first synthesizing means is a first channel signal of a stereo signal, and the output signal of the second synthesizing means is a second channel signal of a stereo signal. 2. The apparatus according to claim 1, further comprising: a first, a second, a third, and a fourth omnidirectional microphone element, wherein a positional relationship between the four microphone elements is defined by the first microphone element and the third microphone element. And a straight line connecting the second microphone element and the fourth microphone element, the output signal of the third microphone element being arranged at an angle. , A second delay means for delaying the output signal of the third microphone element, and an output signal of the first delay means and an output signal of the second delay means. Switching means for switching, first synthesizing means for synthesizing the output signal of the first microphone element and the output signal of the switching means, and delaying the output signal of the fourth microphone element Third delay means for causing
A second synthesizing means for synthesizing an output signal of the microphone element and an output signal of the third delay means, and a selecting means for selecting a switching state of the switching means. A microphone device, wherein an output signal is a first channel signal of a stereo signal, and an output signal of the second synthesizing means is a second channel signal of a stereo signal. 3. The apparatus according to claim 1, further comprising: a first, a second, a third, and a fourth omnidirectional microphone element, wherein a positional relationship between the four microphone elements is defined by the first microphone element and the third microphone element. And a straight line connecting the second microphone element and the fourth microphone element, the output signal of the third microphone element being arranged at an angle. First delay means for delaying the output signal of the first microphone element and the output signal of the first delay means, and an output signal of the first synthesis means. Switching means for switching between the output signal of the third microphone element, selection means for selecting a cut-off state of the switching means, and a delay means for delaying the output signal of the fourth microphone element. And a second synthesizing means for synthesizing an output signal of the second microphone element and an output signal of the second delay means, wherein an output signal of the switching means is a stereo signal. A microphone device comprising: a first channel signal; and an output signal of the second combining means as a second channel signal of a stereo signal. 4. The microphone device according to claim 1, wherein a delay characteristic of said first delay means and a delay characteristic of said second delay means are different from each other. 5. The apparatus according to claim 1, wherein said first delay means and said second delay means are low-pass filters.
The microphone device according to any one of claims 3 to 4. 6. The microphone device according to claim 1, wherein said first delay means and said second delay means are transfer devices. 7. The microphone device according to claim 1, wherein said first delay means and said second delay means perform delay processing by digital signal processing.