JP2760447B2 - Microphone device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microphone device that reduces noise, vibration, and wind noise generated by a video-integrated camera body.

2. Description of the Related Art In recent years, a video-integrated camera has been increasingly used as a device capable of easily recording audio and video. As a result, the functions of video-integrated cameras have been expanded, and their size and weight have been reduced. Hereinafter, a typical example of a microphone device incorporated in a conventional video integrated camera will be described with reference to the drawings.

FIG. 9 shows the appearance of a conventional video-integrated camera, in which 31 is a microphone unit, 32 is a main unit, 33 is a viewfinder, and 34 is a lens unit. Microphone section 31
In order to avoid the influence of noise and vibration generated by the main body 32, the unit is fixed via a vibration-proof material such as rubber and is installed at a position distant from the main body. Further, a windshield is provided to reduce wind noise.

However, when the size of the video-integrated camera is further reduced, the configuration of the video-integrated camera as described above poses practical and design problems. On the other hand, as shown in FIG.
In this case, the microphone section 41 is directly affected by the vibration and noise generated by the main body section 42. Therefore, there is a problem that the S / N ratio at the time of sound pickup is reduced and the sound pickup quality is significantly deteriorated. As a powerful countermeasure to this S / N ratio reduction problem, a method using super-directivity and a method to remove noise using signal processing technology can be considered, but it is difficult in terms of space restrictions and cost. .

For the above reasons, a microphone device satisfying in terms of performance, design and cost has not been developed yet. The present invention provides a microphone device that uses an omnidirectional microphone and a unidirectional microphone to reduce noise, vibration, and wind noise in the direction opposite to the main axis of the microphone unit and that can collect sound with a good S / N ratio. The purpose is to:

Means for Solving the Problems To achieve the above object, a microphone device of the present invention has an omnidirectional microphone unit of the same polarity and a unidirectional microphone unit, and the omnidirectional microphone unit has a main axis that is a video. Aiming at the direction of the integrated camera body, the unidirectional microphone unit has its main axis oriented in the opposite direction to the video-integrated camera main body so that both main axes are parallel to each other, and vibration is applied to the unit. When applied, both units are fixed so as to vibrate together, and the output signal of the omnidirectional microphone unit is passed through a low-pass filter, and the output signal of the unidirectional microphone unit is passed through a high-pass filter and then added.

Further, the present invention has an omnidirectional microphone unit and a unidirectional microphone unit having mutually different polarities, and the omnidirectional microphone unit has its main axis directed toward the video-integrated camera body, and has a unidirectional microphone unit. The main axis is oriented in the opposite direction to the video-integrated camera body, and these two main axes are arranged so as to be opposite to each other.When vibration is applied to the units, both units are fixed so that they vibrate together, and omnidirectional The output signal of the microphone unit is passed through a low-pass filter, and the output signal of the unidirectional microphone unit is passed through a high-pass filter and then subtracted.

However, the polarity of the microphone unit is determined by the sign of the output voltage generated when a positive sound pressure is applied from the front of the unit.

Operation According to the present invention, it is possible to reduce noise, vibration, and wind noise generated by the video-integrated camera main body by the above-described configuration, and sound can be collected with a good S / N ratio.

Embodiment The microphone device of the present invention uses a unit of an omnidirectional microphone and a unit of a unidirectional microphone as a pair. For the low-frequency component of the output of the omnidirectional unit and the high-frequency component of the output of the unidirectional unit, add the signal if both units have the same polarity, and subtract the signal if both units have different polarities. The output of the microphone device.

The difference between the characteristics of the omnidirectional microphone and the unidirectional microphone for sound, vibration, and wind noise will be described below.

First, the sound will be described. When a microphone is used near a sound source, if the sound source is a point sound source, the wavefront of the sound wave will be a spherical wave, and the unidirectional microphone will have a lower frequency range than the case where the wavefront is far from the sound source and a plane wave. Sensitivity in the 0 degree and 180 degree directions with respect to the main axis of the unit is increased. Due to this proximity effect, the unidirectional microphone exhibits a directional characteristic close to bidirectionality. On the other hand, in the high frequency range, the unidirectional microphone has low sensitivity to sound in the direction opposite to the main axis of the unit due to its directivity regardless of the distance from the sound source. On the other hand, the omnidirectional microphone shows a flat frequency characteristic regardless of the distance from the sound source. Therefore, when there is a noise source near the main axis of the unit in the opposite direction, the omnidirectional microphone is more advantageous for noise than the unidirectional microphone in the low frequency range, and the high frequency range In this case, the unidirectional microphone is more advantageous for noise than the non-directional microphone.

Next, vibration will be described. FIG. 8 shows frequency characteristics of vibration sensitivity to sound pressure sensitivity of the non-directional microphone and the unidirectional microphone. In FIG. 8, a solid line indicates an omnidirectional microphone, and a dotted line indicates a unidirectional microphone. As can be seen from FIG. 8, the unidirectional microphone has high sensitivity with respect to vibration in a low frequency range, while the omnidirectional microphone exhibits flat frequency characteristics with respect to vibration. Therefore, an omnidirectional microphone is more advantageous for vibration than a unidirectional microphone.

Next, wind noise will be described. The frequency components of the wind noise are concentrated in the low frequency range, and the omnidirectional microphone is generally less affected by wind noise than the directional microphone. Therefore, an omnidirectional microphone is more advantageous against wind noise than a unidirectional microphone.

From the characteristics of the omnidirectional and unidirectional units described above, the output of the omnidirectional microphone passes through a low-pass filter, the output of the unidirectional microphone passes through a high-pass filter, By using an omnidirectional microphone and a unidirectional microphone in a high frequency range, noise, vibration, and wind noise generated by the video-integrated camera body can be reduced.

When the main axis of the omnidirectional microphone and the main axis of the unidirectional microphone are directed in opposite directions, if both units vibrate integrally, the vibrating membranes of both units will not move together in the main axis direction of the unit. Vibrates in opposite phase.
Therefore, when the polarities of the omnidirectional microphone unit and the unidirectional microphone unit are the same, the output signals of both units are added, and when the polarities are opposite to each other, the output signals of both units are subtracted, whereby the low-pass is obtained. It is possible to cancel the influence of vibration in the main axis direction of the unit at a frequency at which the transmission frequency characteristics of the filter and the high-pass filter overlap.

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

FIG. 1 shows the configuration of a microphone device according to a first embodiment of the present invention, in which 11 is a video-integrated camera body, 12 is an omnidirectional microphone unit, 13
Is a unidirectional microphone unit, 14 is a low-pass filter, 15 is a high-pass filter, 16 is an adder, and 17 is a fixture. The microphone units 12 and 13 are fixed by a fixture 17 so that when vibration is transmitted to the units, both units vibrate integrally. FIG. 3 shows the directional frequency characteristics of a unidirectional microphone when a sound source is located far away, and FIG. 4 shows the directional frequency characteristics of a unidirectional microphone when a sound source is located nearby. 3 and 4, solid lines, broken lines, and dashed lines indicate sensitivities in the directions of 0, 90, and 180 degrees with respect to the main axis of the microphone unit, respectively. In the unidirectional microphone unit 13, when the sound source is close as shown in FIG. 4, the sharpness in the low frequency range due to the proximity effect is larger than when the sound source is far as shown in FIG. An increase in sensitivity occurs. The cut-off frequencies of the low-pass filter 14 and the high-pass filter 15 are set to 1 to 2 kHz, which is the upper limit frequency at which the proximity effect appears. The transfer characteristics of filters 14 and 15 with cutoff frequency set to 1kHz
Shown in the figure. In FIG. 5, the dotted line indicates the low-pass filter 1.
4. The solid line indicates the transfer characteristic of the high-pass filter 15. The output signal of the omnidirectional microphone 12 passes through the low-pass filter 14, and the output signal of the unidirectional microphone unit 13 passes through the high-pass filter 15, and then the outputs of the filters 14, 15 are added to the microphone device of the present embodiment. Get the output of
FIG. 6 shows the directional frequency characteristics of the microphone device of the present embodiment when a sound source is located at a distance, and FIG. 7 shows the directional frequency characteristics of the microphone device of the present embodiment when a sound source is nearby. 6 and 7, solid lines, broken lines, and dashed lines indicate sensitivities in the directions of 0, 90, and 180 degrees with respect to the front of the video integrated camera, respectively. As shown in FIGS. 6 and 7, the microphone device of this embodiment outputs a low-frequency component of the output of the omnidirectional microphone and a high-frequency component of the unidirectional microphone. Further, in the present embodiment, since the omnidirectional microphone 12 and the unidirectional microphone 13 vibrate integrally, near the cutoff frequency of the low-pass filter 14 and the high-pass filter 15 as described above, the vibration component in the main axis direction of the unit is Canceled. As described above, according to the microphone device of the present embodiment, it is possible to reduce noise, vibration, and wind noise generated by the video-integrated camera main body, and sound can be collected with a good S / N ratio.

FIG. 2 shows the configuration of a microphone device according to a second embodiment of the present invention. In FIG. 2, reference numeral 21 denotes a video-integrated camera body, 22 denotes an omnidirectional microphone unit,
Is a unidirectional microphone unit, 24 is a low-pass filter, 25 is a high-pass filter, 26 is a subtractor, and 27 is a fixture. The difference from FIG. 1 is that the polarities of the unit 22 and the unit 23 are opposite to each other and a subtracter 26 is provided. As described above, according to the microphone device of the present embodiment, it is possible to reduce noise, vibration, and wind noise generated by the video-integrated camera main body, and sound can be collected with a good S / N ratio.

As described above, the present invention provides a unidirectional microphone unit having a unidirectional microphone unit and a unidirectional microphone unit having the same polarity, and the main axis of the omnidirectional microphone unit is directed to a video-integrated camera body. The unit has its main axis arranged in parallel with the video-integrated camera body facing in the opposite direction, and is fixed so that both units vibrate when vibration is applied to the unit.The output signal of the omnidirectional microphone unit is a low-pass filter. And the output signal of the unidirectional microphone unit is added after passing through a high-pass filter, so it is possible to reduce the noise, vibration, and wind noise generated by the video-integrated camera body, and reduce the S / N ratio. Good sound pickup can be realized.

In addition, the omnidirectional microphone unit and unidirectional microphone unit with different polarities are oriented to each other with the main axis of the omnidirectional microphone unit facing the video-integrated camera body, and the main axis of the unidirectional microphone unit is integrated with the video. It is arranged in parallel to the camera body in the opposite direction, and when the unit is vibrated, both units are fixed so that they vibrate together.The output signal of the omnidirectional microphone unit passes through a low-pass filter, and the unidirectional microphone is Since the output signal of the unit is subtracted after passing through the high-pass filter, it is possible to reduce noise, vibration and wind noise generated by the video integrated camera body,
Sound pickup with a good S / N ratio can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a microphone device according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of a microphone device according to a second embodiment of the present invention, and FIG. Directional frequency characteristic diagram of unidirectional microphone, 4th
FIG. 5 is a directional frequency characteristic diagram of a unidirectional microphone when a sound source is in the vicinity, FIG. 5 is a frequency characteristic diagram showing a transfer characteristic of a filter according to the first embodiment of the present invention, and FIG. FIG. 7 is a directional frequency characteristic diagram of the microphone device according to the first embodiment of the present invention when a sound source is present. FIG. 7 is a directional frequency characteristic diagram of the microphone device according to the first embodiment of the present invention when a sound source is present in the vicinity. FIG. 8 is a frequency characteristic diagram of vibration sensitivity with respect to sound pressure sensitivity of an omnidirectional microphone and a unidirectional microphone, FIG. 9 is an external view of a conventional video-integrated camera, and FIG. 10 is a microphone incorporated in a main body. It is an external view of the integrated video camera. 11,21… Video integrated camera body, 12, 22… Omni-directional microphone unit, 13, 23… Unidirectional microphone unit, 14, 24… Low-pass filter, 15, 25…
High-pass filter, 16 ... Adder, 26 ... Subtractor, 17,2
7 ... Fixture.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroyuki Naono 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (72) Inventor Yuji Yamashina 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-64-39194 (JP, A) JP-A-61-196698 (JP, A) JP-A-2-41099 (JP, A) JP-A-62-123899 (JP, A) JP-A-63-84272 (JP, A) JP-A-61-40075 (JP, U) (58) Survey ⁶ (Int. Cl. ⁶ , DB name) H04R 3/00 5D020 BB01 + BB05 + BB07 + BB09

Claims (2)

(57) [Claims] An omnidirectional microphone unit having the same polarity and a unidirectional microphone unit, wherein the omnidirectional microphone unit has its main axis directed toward a video-integrated camera body, The unit has its main axis oriented in the opposite direction to the video-integrated camera body, and the main axis of the omnidirectional microphone unit and the main axis of the unidirectional microphone unit are arranged in parallel, and vibration is applied to the unit. When both units are fixed so that they vibrate together, the output signal of the omnidirectional microphone unit is passed through a low-pass filter, and the output signal of the unidirectional microphone unit is passed through a high-pass filter and then added. Microphone device. 2. An omnidirectional microphone unit and a unidirectional microphone unit having different polarities from each other, wherein the omnidirectional microphone unit has its main axis directed toward the video-integrated camera body, and has the unidirectional microphone unit. The microphone unit arranges the main axis of the omnidirectional microphone unit and the main axis of the unidirectional microphone unit in parallel with the main axis facing in the opposite direction to the video-integrated camera body, and when vibration is applied to the unit. The two units are fixed so as to vibrate integrally, the output signal of the omnidirectional microphone unit is passed through a low-pass filter, and the output signal of the unidirectional microphone unit is subtracted after passing through a high-pass filter. Microphone device.