CN105323679A - Microphone device - Google Patents

Abstract

The invention relates to a microphone device which is capable of outputting sound signals with less noise under a noise generating environment. The microphone device comprises a first uni-directional microphone (10), a second uni-directional microphone (20), wherein the directional axis of the second microphone (20) is virtually identical with the directional axis of the first microphone (10), and the second microphone (20) and the first microphone (10) are arranged in a front and back sequence along the axis; a noise detection part (30) which is used for detecting noise contained in output signals of the first microphone (10); and a control part (40) which is used for controlling the output of the first microphone (10) and the second microphone (20) based on the detection result of the noise detection part (30).

Description

Microphone device

technical field

The present invention relates to microphone devices.

Background technique

There is known a composite microphone device in which a plurality of microphones are mounted in one microphone case. In many composite microphone devices, two microphones are built into one microphone case. Among the composite microphone devices, a composite microphone device in which two microphones are built in one microphone case is also called a dual microphone.

The composite microphone device can output an audio signal from any one of a plurality of microphones. Therefore, even when one of the plurality of microphones is unusable due to failure or the like, the composite microphone device can be used by switching to an output signal from another microphone.

A unidirectional electret condenser microphone is often used in a composite microphone device used on a podium or the like. The electret condenser microphone can prevent howling and the like even when a plurality of microphones are arranged adjacent to each other. In addition, an electret condenser microphone does not require a power source for generating a polarization voltage.

In a composite microphone device having a structure in which a plurality of microphones are arranged in a width direction, the sound quality of the plurality of microphones hardly differs, but the outer shape of the housing increases in proportion to the number of microphones mounted therein.

In a composite microphone device having a structure in which a plurality of unidirectional microphones are arranged in a row on the directional axis of the composite microphone device, the outer shape of the housing can be reduced.

However, the unidirectional condenser microphone tends to generate noise caused by wind from an air conditioner or the like (wind noise), pop noise caused by air flow such as plosive sounds of a speaker, and noise caused by air flow.

In a composite microphone device in which unidirectional microphones are mounted in a row along the longitudinal direction on the directional axis, the microphone mounted in front (closer to the speaker) tends to pick up the speaker's voice, so it is used as the main microphone. However, the microphone mounted on the front also tends to pick up the above-mentioned noise caused by the airflow.

Therefore, in the conventional composite microphone device, if the front microphone picks up noise, an audio signal with little noise cannot be output.

In addition, there is disclosed a technique for switching and outputting two types of signals, that is, outputting the output signal of one of two omnidirectional microphones, or outputting a signal obtained by adding an output signal of one microphone to an inverted signal of the other microphone. (For example, refer to Patent Document 1).

In the technique disclosed in Patent Document 1, when ambient noise is low, an output signal of one microphone is added to an output signal of the other microphone to output a signal with strong directivity. In addition, in the technique disclosed in Patent Document 1, when the surrounding noise is high, only the output signal of one microphone is output.

In the technique disclosed in Patent Document 1, when high noise is generated in the vicinity of one microphone, the noise is easily picked up. Therefore, even the technique disclosed in Patent Document 1 cannot output an audio signal with little noise.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 9-149490

Contents of the invention

An object of the present invention is to provide a microphone device capable of outputting an audio signal with less noise even in an environment where noise is generated.

The present invention is characterized in that it has: a unidirectional first microphone; a unidirectional second microphone whose directional axis is substantially in the same direction as the directional axis of the first microphone, and the 2nd microphone and the 1st microphone are on the same axis. Arranged along the upper edge; a noise detection unit that detects noise contained in the output signal of the first microphone; and a control unit that controls the output of the first microphone and the second microphone based on the detection result of the noise detection unit.

Invention effect

According to the present invention, even in an environment where noise is generated, it is possible to output an audio signal with little noise.

Description of drawings

FIG. 1 is a partial cross-sectional view showing an embodiment of a microphone device according to the present invention.

FIG. 2 is an enlarged sectional view of a microphone housing of the microphone device of FIG. 1 .

FIG. 3 is a graph showing directivity characteristics of a first microphone of the microphone device of FIG. 1 .

FIG. 4 is a graph showing the directivity characteristics of a second microphone of the microphone device of FIG. 1 .

FIG. 5 is a graph showing the directional frequency characteristics of a first microphone of the microphone device shown in FIG. 1 .

FIG. 6 is a graph showing the directional frequency characteristics of the second microphone of the microphone device of FIG. 1 .

FIG. 7 is a circuit diagram of the microphone device of FIG. 1 .

FIG. 8 is a circuit diagram showing another embodiment of the microphone device according to the present invention.

Explanation of reference signs

1 microphone unit

2 microphone housings

3 support pipe

4 flexible tubes

5 base frame

6 openings

7 openings

8 tail pipes

9 covers

10 1st microphone

11 sound department

12 circuit substrate

20 2nd microphone

21 sound department

22 circuit substrate

30 low pass filter

40 switch drivers

50 volume driver

100 Microphone Unit

SW1 switch

SW2 switch

VR digital volume controller

detailed description

●Microphone unit (1)●

Hereinafter, embodiments of the microphone device according to the present invention will be described with reference to the drawings.

FIG. 1 is a partial cross-sectional view showing an embodiment of a microphone device according to the present invention. As the microphone device according to the present embodiment, a gooseneck-type dual microphone is shown in FIG. 1 as an example. As shown in the figure, the microphone device 1 has a microphone case 2 that accommodates the first microphone 10, the second microphone 20, and the like.

Also, the microphone device 1 includes a support pipe 3 that supports the microphone housing 2 , a flexible pipe 4 that supports the support pipe 3 , and a base housing 5 that supports the flexible pipe 4 having an output connector (not shown) and the like.

FIG. 2 is an enlarged cross-sectional view of a portion of the microphone case 2 of the microphone device 1 . As shown in the figure, the microphone case 2 has a cylindrical shape having openings at both ends. The microphone case 2 has an inner diameter and a length capable of accommodating the first microphone 10 and the second microphone 20 therein.

The microphone case 2 has an opening 6 for collecting sound from the outside in a peripheral wall portion corresponding to the sound collecting portion 11 of the first microphone 10 . The microphone case 2 has an opening 7 for collecting sound from the outside in a peripheral wall portion corresponding to the sound collecting portion 21 of the second microphone 20 .

A tailpiece 8 is attached to the opening end of the microphone case 2 on the support pipe 3 side so as to close the opening end. In addition, a cover 9 covering the opening end of the microphone case 2 is attached to the opening end on the opposite side (front end side) to the side on which the tail pipe 8 is attached. An opening for collecting sound from the front end side of the microphone device 1 is provided on the cover 9 .

The first microphone 10 is accommodated near the front end of the microphone case 2 so that the sound collecting unit 11 is located near the opening 6 as described above. In addition, the second microphone 20 is accommodated in the microphone housing 2 at a position close to the tail pipe 8 so that the sound collecting portion 21 is located near the opening 7 as described above. The first microphone 10 and the second microphone 20 are arranged front and rear in the longitudinal direction of the microphone case 2 .

The first microphone 10 and the second microphone 20 are unidirectional electret condenser microphones. The directing axes of the first microphone 10 and the second microphone 20 may be substantially in the same direction, for example, the directing axes may be coaxial. Both the first microphone 10 and the second microphone 20 are directed toward the direction of the cover 9 of the microphone case 2 . That is, the microphone device 1 is oriented with the direction of the cover 9 of the microphone case 2 (the front end direction) as the direction of the directional axis.

In addition, in the microphone device according to the present invention, there may be three or more microphones whose directional axes are substantially in the same direction.

In the microphone device 1 , the first microphone 10 is arranged near the front end of the microphone case 2 . In the microphone device 1 , a cover 9 having an opening is provided on the front end side of the microphone case 2 .

FIG. 3 is a graph showing the directivity characteristics of the first microphone 10 of the microphone device 1 . In addition, FIG. 4 is a graph showing the directivity characteristics of the second microphone 20 of the microphone device 1 . According to FIGS. 3 and 4, compared with the second microphone 20 stored at a position close to the tail pipe 8, the direction of the first microphone 10 disposed near the front end of the microphone housing 2 is directed toward the front end of the microphone device 1. stronger features.

That is, in the microphone device 1 , the first microphone 10 is more likely than the second microphone 20 to pick up the voice of the speaker located in the forward direction.

FIG. 5 is a graph showing the directional frequency characteristic of the first microphone 10 of the microphone device 1 . In addition, FIG. 6 is a graph showing the directional frequency characteristic of the second microphone 20 of the microphone device 1 . According to FIG. 5 and FIG. 6, it can be seen that the output levels of the first microphone 10 and the second microphone 20, which are both shown by thick solid lines, hardly change at 0 degrees. In contrast, the output levels of 90 degrees, 180 degrees, and 120 degrees The output level has decreased.

A circuit board 12 constituting an electrical circuit of the first microphone 10 is accommodated in the first microphone 10 . In addition, a circuit board 22 constituting an electrical circuit of the second microphone 20 is housed in the second microphone 20 .

FIG. 7 is a circuit diagram of the microphone device 1 of FIG. 1 . As shown in this figure, a low-pass filter (lowpass filter) 30 is provided in the microphone device 1, and this low-pass filter 30 makes only the sound signal of a predetermined range (low-range sound signal) in the sound signal acquired by the first microphone 10 )pass.

The low-pass filter 30 functions as a noise detection unit that detects a sound component corresponding to noise contained in the output signal of the first microphone 10 . Here, as described above, since the first microphone 10 is located close to the speaker, it is easy to pick up noise components caused by air flow, such as wind noise and blast noise. Therefore, the low-pass filter 30 functions as a noise detection sensor.

The microphone device 1 is provided with a switch driver (SWD) 40 that switches the switch SW1 based on the detection result of the low-pass filter 30 , that is, the detected low-range sound signal.

The switch driver 40 compares the level of the low-range audio signal passing through the low-pass filter 30 with a predetermined cutoff signal level. Here, the predetermined cutoff signal level is a critical level (threshold value) of noise components (for example, a frequency of about 100 Hz) obtained from the first microphone 10 due to airflow such as wind noise and air explosion noise, and is stored in the switch. An unillustrated storage unit of the drive 40 .

The switch driver 40 determines which of the first microphone 10 and the second microphone 20 to switch the microphone outputting the audio signal from the comparison result of the level of the cutoff signal and the level of the low-range audio signal.

In addition, the microphone device 1 is provided with a switch SW1 for switching the output from the first microphone 10 and the output from the second microphone 20 based on a comparison result of the cutoff signal level and the low-range audio signal level.

The switch SW1 corresponds to a control unit, switches the output signal from the first microphone 10 and the output signal from the second microphone 20, and outputs only the signal from one of the microphones.

For example, an electronic digital switch capable of switching is used for the switch SW1. The switch SW1 can switch the output of the first microphone 10 and the second microphone 20 by the switch driver 40 .

Furthermore, the microphone device 1 is provided with a switch SW2 for the user to manually switch between the output of the first microphone 10 and the output of the second microphone 20 . The switch SW2 is used for selecting one of the normally operating microphones when one of the first microphone 10 and the second microphone 20 cannot be used due to a failure.

In the microphone device 1 , the outputs of the first microphone 10 and the second microphone 20 are switched by the switch SW1 based on the result of noise detected by the low-pass filter 30 from the detected low-range sound signal.

Therefore, according to the microphone device 1 , when the noise is small, it is possible to output a sound with good sound quality from the sound signal of the first microphone 10 located close to the speaker's mouth. In addition, according to the microphone device 1 , when the noise is large, it is possible to output a sound with little noise using the sound signal from the second microphone 20 which is far from the speaker's mouth.

In particular, according to the microphone device according to the present embodiment, it is possible to output sound with little noise even when noise due to air currents such as wind noise and blast noise is generated.

●Microphone units (2)●

Next, with respect to other embodiments of the microphone device according to the present invention, only differences from the embodiments described above will be described.

FIG. 8 is a circuit diagram showing another embodiment of the microphone device according to the present invention. As shown in the figure, the microphone device 100 according to the present embodiment includes a digital volume controller (electronic volume controller including semiconductors) VR controlled by a volume driver 50 . The digital volume controller VR is different from the microphone device 1 described above in that it replaces the switch SW2 of the microphone device 1 described above.

During the period from the output from only the first microphone 10 to the output from only the second microphone 20, the digital volume controller VR can make the output ratio of the first microphone 10 and the second microphone 20 stepwise or non-stepwise. sex change. That is, the digital volume controller VR has the function of making the first microphone 10 output the output of the first microphone 10 and the second microphone 20 as follows: only the first microphone 10 is output, or the first microphone 10 and the second microphone 20 are output. The output is mixed and output, or only the second microphone 20 is output.

As described above, the digital volume controller VR is controlled by the volume driver 50 . An output signal of the microphone device 100 is output from a terminal corresponding to a variable output terminal of the digital volume controller VR.

The volume driver 50 replaces the switch driver 40 described above. The volume driver 50 controls the digital volume controller VR according to the level of the low-range audio signal output from the low-pass filter 30 .

Therefore, the microphone device 100 can control the output ratio of the first microphone 10 and the second microphone 20 based on the level of the low-range audio signal from the first microphone 10 .

Unlike the microphone device 1 described above, the microphone device 100 can mix the output of the first microphone 10 and the output of the second microphone 20 at a ratio corresponding to the value of the digital volume controller VR to output an audio signal of the microphone device 100 .

●Effect of implementation ●

As described above, according to the microphone device according to the present embodiment, the following effects can be obtained.

In the microphone device according to the present embodiment, noise is detected from the sound signal of the first microphone, and outputs of the first microphone and the second microphone are controlled. Therefore, according to the microphone device according to the present embodiment, even in an environment where noise is generated, it is possible to output an audio signal with little noise.

In addition, according to the microphone device according to the present embodiment, even when noise caused by air currents such as wind noise and blast noise is generated, it is possible to output an audio signal with little noise.

In addition, according to the microphone device according to the present embodiment, the ratio of the outputs of the first microphone 10 and the second microphone 20 (mixing ratio of audio signals) can be adjusted to a state with less noise according to the presence or absence and magnitude of noise.

Claims (8)

1. A microphone device having: Unidirectional 1st microphone; A second microphone with a single directivity, the pointing axis of which is substantially the same direction as the pointing axis of the first microphone, and the second microphone and the first microphone are arranged along the front and rear in the axial direction; a noise detection unit that detects noise contained in the output signal of the first microphone; and A control unit that controls outputs of the first microphone and the second microphone based on the detection result of the noise detection unit. 2. The microphone arrangement according to claim 1, wherein, The control unit outputs only the output of the first microphone, or outputs a mixture of the output of the first microphone and the output of the second microphone. 3. The microphone arrangement according to claim 1, wherein, The control unit outputs only one of the output of the first microphone and the output of the second microphone. 4. The microphone arrangement according to claim 1, wherein, The control unit controls a ratio of outputs of the first microphone and the second microphone based on the detection result. 5. The microphone arrangement according to claim 1, wherein, The noise detection unit detects noise caused by airflow included in the output signal of the first microphone. 6. The microphone arrangement according to claim 1 , wherein: The noise detection unit includes a low-pass filter. 7. The microphone arrangement according to claim 1 , wherein: The microphone device has a housing that houses the first microphone and the second microphone therein, The housing includes openings for introducing sound into the first microphone and the second microphone. 8. The microphone arrangement according to claim 1 , wherein: A directivity characteristic of the first microphone toward the distal direction is stronger than a directivity characteristic of the second microphone toward the distal direction.