JP2006303839A - Microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microphone from which a spread sense and a presence can be obtained even when a 4-channel microphone is connected to a 2-channel acoustic apparatus. <P>SOLUTION: Sound signals FL1. FR1, RL1, RR1 picked up by the 4-channel microphone unit are introduced from input terminals 21<SB>I</SB>to 24<SB>I</SB>. In the case of connection of a 4-channel acoustic apparatus, a changeover switch 15 is opened to output input signals as 4-channel sound signals FL, FR, RL, RR. In the case of connection of the 2-channel acoustic apparatus, a changeover switch 15 is closed and a front left channel sound signal L1 resulting from mixing an inverse signal (a FR2 component) of a front right sound signal and an in-phase signal (a RL1 component) of a rear left sound signal to the front left sound signal FL1 is output to an output terminal 21<SB>O</SB>, and a right channel sound signal R resulting from mixing an inverse signal (a FL2 component) of a front left sound signal and an in-phase signal (a RR1 component) of a rear right sound signal to the front right sound signal FR1 is output to an output terminal 22<SB>O</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microphone having a function capable of adapting a 4-channel microphone to a 2-channel audio device.

Conventionally, in a four-channel microphone that records sound signals corresponding to four channels of the front left channel, the front right channel, the rear left channel, and the rear right channel, for example, as described in Patent Document 1 below, It has been proposed to obtain a surround sound signal.
In addition, as described in Japanese Patent Laid-Open No. 5-191877, a four-channel audio signal is obtained by using two unidirectional microphone units and one bidirectional microphone unit. A so-called M-S type microphone has been proposed. JP 57-42296 A

  The 4-channel microphone has only a function category corresponding to a 4-channel audio device. Therefore, when a 4-channel microphone is connected to a 2-channel audio device, only 2 channels out of 4 channels can be used effectively, and the function as a 4-channel microphone cannot be fully utilized.

  That is, when 2-channel reproduction is performed using a 4-channel microphone, it is impossible to obtain a sense of spaciousness or realism.

  Therefore, for example, the sound signal of the front right channel of the 4-channel microphone is mixed with the right phase signal of the rear right channel and the reverse phase signal of the rear left channel is mixed, and the sound signal of the front left channel is mixed with the rear left channel. By mixing the right-phase signal of the rear and the reverse-phase signal of the right rear channel, even in normal 2-channel playback, the 4-channel sound source can be used effectively to provide a sense of breadth and presence. Conceivable.

  However, when configured in this way, there are the following contradictory phenomena in the direction reproducibility. That is, for example, if the right-phase backward normal phase component sound is small in the synthesized right signal component, the right-phase backward reverse phase component of the synthesized left signal is localized in the sound field. A phenomenon occurs in which the sound that should be heard can be heard from the front left, and the sound that should be located in the rear left can be heard from the front right as well. This is because there are few output components of the positive phase of an antiphase sound source.

  Therefore, the synthesis amount of the reverse phase component cannot be increased. Moreover, when there are few reverse phase components, the effect of a feeling of spread and a feeling of presence will decrease.

  The present invention has been made in view of the above points, and an object of the present invention is to utilize a 4-channel function even when a 4-channel microphone is connected to a 2-channel audio device, and to generate a 4-channel sound source even in normal 2-channel playback. It is an object of the present invention to provide a microphone that can provide a sense of expanse and a sense of realism, and has excellent direction reproducibility.

  In order to obtain a sense of breadth and presence in 2-channel playback of 2-channel audio equipment, it has been generally realized by processing a 2-channel sound source. This processing includes a method of inverting the phase of the sound sources of the two channels L and R and adding the sound whose level is adjusted to the original L and R in reverse, and a sound source of the two channels L and R as a differential amplifier. In addition, the output level is adjusted and added to the original L and R so that they are out of phase, and the 2-channel L and R sound sources are added to the differential amplifier to adjust the output level. There is a method of delaying the phase and adding it to the original L and R.

  On the other hand, in the present invention, among the four-channel sound sources (front left and right, rear left and right), the sound source of the left and right front two channels is processed as described above, and the left and right two channels are respectively processed as the left channel and the rear left channel. By adding the rear right channel to the right channel, the 4-channel sound source is effectively used, and the sense of breadth and presence can be expressed more effectively than the method using the 2-channel sound source.

  Furthermore, the phenomenon that the sound that should be on the rear left can be heard from the front right, and the sound that should be on the rear right can be heard from the front left as well, and good direction reproducibility can be obtained.

  That is, the present invention has a plurality of microphone units, and a 4-channel sound signal introducing means for inputting sound signals corresponding to four channels of the front left channel, the front right channel, the rear left channel, and the rear right channel; A 4-channel signal circuit for outputting a sound signal corresponding to the four channels input by the sound signal introducing means as a 4-channel sound signal; and a 2-channel sound signal from the 4-channel sound signal input by the 4-channel sound signal introducing means. A circuit that mixes the front left channel sound signal with the front left channel sound signal and mixes the front left channel sound signal with the front right channel sound signal. The two-channel signal circuit, and the output of the four-channel sound signal and the two-channel sound signal. It is characterized in that a changing switch means.

  The two-channel signal circuit includes a circuit that mixes the in-phase signal of the rear left channel with the sound signal of the front left channel and mixes the in-phase signal of the rear right channel with the sound signal of the front right channel. It is characterized by being.

  In addition, the anti-phase signal level of each channel to be mixed is set to a level that does not exceed the level of the in-phase signal of each of the mixed channels within the range of main directivity angles of the plurality of microphone units. It is a feature.

  Further, the four-channel sound signal introducing means is characterized by having first to fourth microphone units having directivity and arranged by shifting the central axis by 90 ° from each other.

  The four-channel sound signal introducing means is shifted by 90 ° with respect to the directions of the unidirectional first and second microphone units directed in opposite directions and the first and second microphone units. A bi-directional third microphone unit directed in the direction and the outputs of the first and third microphone units are added to obtain a sound signal of the front left channel, and the first and third microphone units The output is subtracted to obtain the sound signal of the front right channel, and the outputs of the second and third microphone units are added to obtain the sound signal of the rear left channel, and the outputs of the second and third microphone units are obtained. And an arithmetic unit that obtains a sound signal of the rear right channel by subtraction.

  In the above configuration, when the microphone of the present invention is connected to a 4-channel audio device, the switching means is switched to the 4-channel sound signal output side. Then, the sound signals of the four channels of the front left channel, the front right channel, the rear left channel, and the rear right channel introduced from the plurality of microphone units are output as they are through the four channel signal circuit, and four channel reproduction is performed. .

  When the microphone of the present invention is connected to a 2-channel audio device, the switching means is switched to the 2-channel sound signal output side. Then, the two-channel signal circuit, for example, mixes the front left channel reverse phase signal introduced from a plurality of microphone units with the front right channel sound signal and the front right channel reverse phase signal to the front left channel. The sound signal is mixed, the rear right channel signal is mixed with the front right channel sound signal, the rear left channel signal is mixed with the front left channel sound signal, and a two-channel sound signal is generated and output. As a result, two-channel reproduction is performed.

  At this time, since the sound of the opposite phase of the front left channel is mixed in the front right channel and the sound of the opposite phase of the front right channel is mixed in the front left channel, the sound is not localized in the center of the left and right speakers, The feeling of localization of the sound is blurred and the feeling of localization is as if the left and right speakers are spread. In addition, the sound recorded from the back will be more realistic.

(1) According to the present invention, it is possible to obtain a two-channel sound signal that effectively uses all four-channel sound sources. For this reason, when a two-channel audio device is connected and played back, a sense of spaciousness and presence is effectively expressed.

  In particular, compared with the conventional method of processing a two-channel sound source, a sense of breadth and presence can be obtained, and good direction reproducibility can be obtained. The effect is further enhanced by combining with video.

Furthermore, the microphone of the present invention provides an added value that can be used not only for a 4-channel audio device but also for a 2-channel audio device.
(2) According to the invention described in claim 4, in the microphone including the first to fourth microphone units having directivity and arranged by shifting the central axis by 90 ° from each other, the (1 ) Is obtained.
(3) According to the invention described in claim 5, the unidirectional first and second microphone units oriented in opposite directions to each other and the directions of the first and second microphone units. A so-called M-S (Mid-Mid-M-S), which has a bi-directional third microphone unit oriented in a direction shifted by 90 °, and obtains 4-channel sound signals from the outputs of these three microphone units. Side) type microphones can achieve the same effect as the above (1).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the appearance of an embodiment in which the present invention is applied to a video camcorder capable of recording video and audio. In FIG. 1, a main body 10 of a video camcorder is provided with a four-channel microphone 20 having four directional microphone units 11 to 14 and a changeover switch 15.

  The directional microphone unit 11 is arranged toward the front left side of the camera and records the sound source (FL) of the front left channel.

  The directional microphone unit 12 is arranged toward the front right side of the camera and records a sound source (FR) of the front right channel.

  The directional microphone unit 13 is arranged toward the rear left side of the camera and records a sound source (RL) of the rear left channel.

  The directional microphone unit 14 is arranged toward the rear right side of the camera and records the sound source (RR) of the rear right channel.

  The change-over switch 15 is a change-over switch that switches between a 4-channel audio device use mode and a 2-channel audio device use mode. For example, when the open channel is selected and the 4-channel audio device use mode is selected, the directional microphone units 11 to 14 are selected. The 4-channel sound signal recorded in the above is output as it is, and when the 2-channel sound equipment use mode is selected by closing, the 4-channel sound signal recorded by the directional microphone units 11 to 14 is effectively used to create the sound signal. The two-channel sound signal is output.

  FIG. 2 shows the electrical configuration of the 4-channel microphone 20 and the planar arrangement of the directional microphone units 11 to 14. In FIG. 2, the encoder 1 does not operate when the changeover switch 15 is opened (when the 4-channel audio equipment use mode is selected), and the 4-channel sound source recorded by the directional microphone units 11 to 14 remains as it is. Output as signals FL, FR, RL, RR.

  The encoder 1 acts when the change-over switch 15 (FIG. 3) is closed (when the 2-channel audio equipment use mode is selected), and the 2-channel sound from the 4-channel sound source recorded by the directional microphone units 11-14. Create and output signals L and R. At this time, the sound signals RL and RR of the rear left channel and the rear right channel are not used.

Next, a detailed circuit of the encoder 1 will be described with reference to FIG. In Figure 3, the input terminal 21 _I, directional front left audio signal FL1 was recorded by the microphone unit 11 is input to the input terminal 22 _I, directional front right audio signal FR1 was recorded by the microphone unit 12 Is input to the input terminal 23 _I , and the rear left audio signal RL1 recorded by the directional microphone unit 13 is input to the input terminal 23 _{I. The} rear right audio signal RR1 recorded by the directional microphone unit 14 is input to the input terminal 24 _I. Is entered.

The input terminal 21 _I is connected to the input terminal of the inverting amplifier 27FL for inverting the phase, and is connected to one input terminal of the adder 25L, and the output terminal of the adder 25L is connected to the output terminal 21 _O.

The input terminal 22 _I is connected to the input terminal of the inverting amplifier 27FR that inverts the phase, and is connected to one input terminal of the adder 25R, and the output terminal of the adder 25R is connected to the output terminal 22 _O.

The input terminal 23 _I is connected to the output terminal 23 _O and to one end of a level adjustment resistor 26RL1.

The input terminal 24 _I is connected to the output terminal 24 _O and to one end of a level adjusting resistor 26RR1.

  The output terminal of the inverting amplifier 27FL is connected to one end of the level adjusting resistor 26FL2, and the output terminal of the inverting amplifier 27FR is connected to one end of the level adjusting resistor 26FR2.

  A common connection point between the other ends of the resistor 26RL1 and the resistor 26FR2 is connected to the other input terminal of the adder 25L via a contact 15L of the changeover switch 15.

  A common connection point between the other ends of the resistor 26RR1 and the resistor 26FL2 is connected to the other input end of the adder 25R via a contact 15R of the changeover switch 15.

  The contacts 15L and 15R of the changeover switch 15 are interlocked.

When the circuit configured as described above is connected to a 4-channel audio device, the changeover switch 15 is opened. In this case, the 4-channel sound input from the input terminals 21 _{I to} 24 _I is directly output from the output terminals 21 _{O to} 24 _O as the 4-channel sound signals FL, FR, RL, and RR.

When connecting to a 2-channel audio device, the changeover switch 15 is closed. In this case, the reverse-phase signal FR2 phase-inverting the front right audio signal FR1 input from the input terminal 22 _I in the inverting amplifier 27FR and level adjustment by a resistor 26FR2, input from the input terminal 23 _I rear left audio signal RL1 Is applied to the adder 25L via the contact 15L.

Therefore, a left channel sound signal obtained by mixing the front left audio signal FL1 with the reverse phase signal (FR2 minutes) of the front right audio signal and the in-phase signal (RL1 minutes) of the rear left audio signal at the output terminal 21 _O. L is output.

The resistance inverted signal FL2 whose level is adjusted by the phase inversion resisting 26FL2 by inverting amplifier 27FL a front left audio signal FL1 input from the input terminal 21 _I, a rear right audio signal RR1 input from the input terminal 24 _I 26RR1 The in-phase signal whose level is adjusted in (1) is applied to the adder 25R via the contact 15R.

Therefore, a right channel sound signal obtained by mixing the front right audio signal FR1 with the reverse phase signal (FL2 minutes) of the front left audio signal and the in-phase signal (RR1 minutes) of the rear right audio signal at the output terminal 22 _O. R is output.

For this reason, the sound reproduced by the two-channel audio equipment connected to the output terminals 21 _O and 22 _{O from} which the two-channel sound signals L and R are derived is not localized at the center of the left and right speakers, and the sound localization is blurred. , It feels as if the left and right speakers spread. Further, the signals RL1 and RR1 to be mixed are recorded from the rear, so that the sense of reality is more full.

  Note that the levels of the anti-phase signals FL2 and FR2 of the respective channels mixed in the adders 25L and 25R in FIG. 3 are within the range of the main directivity angles of the microphone units 11 to 14, that is, 90 degrees on the left and right with respect to the main axis. The resistors 26RL1 and 26RR1 are adjusted so as not to exceed the level of the in-phase signal of the mixed channels.

  Next, regarding the balance between the reverse phase signal and the in-phase signal of the two-channel sound signals L and R (pseudo 4-channel stereo) of the present invention created by mixing the reverse phase signals FL2 and FR2 as described above, in all directions. The polar pattern representing the signal level is verified together with FIGS.

  FIG. 4 shows the polar pattern of the stereo microphone when the reverse phase signal is adjusted well. In this case, it can be seen that the level of the reverse phase signal does not exceed the level of the in-phase signal up to 120 ° to the left and right.

  In other words, in the R channel, the in-phase signal level of 115 ° is 1.75> 245 ° and the in-phase signal level is 1.6, and the in-phase signal level of 120 ° is 1.6 = 240 °. Is 1.6, and the in-phase signal level of 125 ° is 1.5, and the reverse phase signal level of 1.4 <235 ° is 1.5.

  In the L channel, the in-phase signal level of 245 ° is 1.75> 115 ° and the in-phase signal level is 1.6, and the in-phase signal level of 240 ° is 1.6 = 120 °. 1.6, the in-phase signal level of 235 ° is 1.4 <125 °, and the anti-phase signal level of 1.5 is 1.5.

  FIG. 5 shows a polar pattern when the level of the reverse phase signal is too small. In this case, the level of the reverse phase signal does not exceed the level of the in-phase signal, but the sense of reality created by the reverse phase signal is lost.

  That is, in the R channel, the in-phase signal level at 120 ° is 1.6> 240 ° and the in-phase signal level is 1.1, and the in-phase signal level at 160 ° is 0.7> 200 °. Is 0.6.

  In the L channel, the in-phase signal level of 240 ° is 1.6> 120 ° and the in-phase signal level is 1.1, and the in-phase signal level of 200 ° is 0.7> 160 °. Is 0.6.

  FIG. 6 shows a polar pattern when the level of the reverse phase signal is too large, contrary to FIG. In this case, since the reverse phase exceeds the level of the in-phase signal within 90 ° left and right, the rear left sound is localized to the front right and the rear right sound is localized to the front left, giving a sense of direction. It will be damaged.

  That is, in the R channel, the 90 ° in-phase signal level is 2.55 <270 ° and the reverse phase signal level is 2.7, and the 100 ° in-phase signal level is 2.3 <260 °. Is 2.85.

  In the L channel, the 270 ° in-phase signal level is 2.55 <90 °, the reverse phase signal level is 2.7, and the 260 ° in-phase signal level is 2.3 <100 °. Is 2.85.

  Therefore, as a more preferred embodiment of the present invention, the balance between the reverse phase signal and the in-phase signal of the two-channel sound signals L and R (pseudo four-channel stereo) is a polar pattern as shown in FIG. The constants of the microphone units 11 to 14, the inverting amplifiers 27FL and 27FR, and the resistors 26FL2, 26FR2, 26RL1, and 26RR1 in FIG. 3 are adjusted.

  Next, the present invention is directed to unidirectional first and second microphone units oriented in opposite directions, and in a direction shifted by 90 ° with respect to the orientation of the first and second microphone units. An embodiment applied to an M-S (Mid-Side) microphone equipped with a third bidirectional microphone unit will be described with reference to FIG.

  In FIG. 7, the microphone 30 of the present embodiment includes unidirectional first and second microphone units 31 and 32 (M1 and M2) arranged in opposite directions (front and rear directions), and those A third microphone unit 33 (S1) that is bi-directional and is oriented in a direction shifted by 90 ° with respect to the direction of the microphone units 31 and 32;

  The encoder 2 adds and subtracts the outputs of the three microphone units 31 to 33 to obtain four-channel audio signals of front left (FL), front right (FR), rear left (RL), and rear right (RR). That is, for example, as disclosed in Patent Document 2, the encoder 2 adds the outputs of the first and third microphone units 31 and 33 to obtain a front left audio signal, and the first and third microphone units 31. , 33 is subtracted to obtain the front right audio signal, and the outputs of the second and third microphone units 32, 33 are added to obtain the rear left audio signal, and the second and third microphone units 32, 33 are obtained. Is obtained by subtracting the output of the rear right audio signal.

  Each output signal of the encoder 2 is introduced into the encoder 1 configured in the same manner as in FIG. Note that the microphone 30 in FIG. 7 is also provided with the same changeover switch 15 (not shown).

  When the microphone 30 configured as described above is connected to a 4-channel audio device, the changeover switch 15 is opened. In this case, the encoder 1 does not act, and the four-channel sound signals recorded by the three microphone units 31 to 33 and obtained by the operation of the encoder 2 are directly used as the four-channel sound signals FL, FR, RL, and RR. Is output.

  When connecting to a 2-channel audio device, the changeover switch 15 is closed. In this case, the encoder 1 operates, and the 2-channel sound signals L and R are generated and output from the 4-channel audio signals calculated by the encoder 2 in the same manner as the operation described in FIG. At this time, the sound signals RL and RR of the rear left channel and the rear right channel are not used.

  The two-channel signal circuit for generating and outputting a two-channel sound signal from the four-channel sound signal of the present invention is not limited to using the inverting amplifiers 27FL and 27FR and the resistors 26FL2 and 26FR2, but the front left and right audio signals FL1. , FR1 may be added to the differential amplifier, the output level thereof may be adjusted, and added to the front left and right audio signals FL1, FR1 so as to be in opposite phases.

The perspective view of the embodiment which applied this invention to the video camcorder. 1 is a configuration diagram of a four-channel microphone 20 according to an embodiment of the present invention. The circuit diagram which shows one Example of the principal part of this invention. The characteristic view which shows the polar pattern of the L channel and R channel in the example of embodiment of this invention in case the balance of a negative phase signal is good. The characteristic view which shows the polar pattern of the L channel and R channel in case the reverse phase signal is too weak in the example of embodiment of this invention. The characteristic view which shows the polar pattern of the L channel and R channel in the case of excessive antiphase signal in the example of embodiment of this invention. The block diagram of the microphone 30 of the other embodiment of this invention.

Explanation of symbols

1,2 ... encoder, 10 ... video camcorder body, 11 to 14 ... directional microphone unit, 15 ... change-over switch, 20 ... 4-channel microphone, 21 _I to 24 _I ... input terminal, 21 _O to 24 _O ... Output terminal 25L, 25R ... adders, 26RL1, 26RR1, 26FL2, 26FR2 ... resistors, 27FL, 27FR ... inverting amplifiers, 30 ... microphones, 31 ... unidirectional first microphone unit, 32 ... unidirectional first 2 microphone units, 33... Bidirectional third microphone unit.

Claims (5)

A four-channel sound signal introducing means that has a plurality of microphone units and inputs sound signals corresponding to four channels of a front left channel, a front right channel, a rear left channel, and a rear right channel;
A 4-channel signal circuit for outputting, as a 4-channel sound signal, a sound signal corresponding to the 4-channel input by the 4-channel sound signal introducing means;
A circuit that creates and outputs a two-channel sound signal from the four-channel sound signal input by the four-channel sound signal introduction means, and mixes the sound signal of the front right channel with the reverse phase signal of the front left channel; A two-channel signal circuit having a circuit for mixing a sound signal of the front left channel with a reverse phase signal of the front right channel;
A microphone comprising: switching means for switching output of the 4-channel sound signal and 2-channel sound signal. The two-channel signal circuit has a circuit that mixes the in-phase signal of the rear right channel with the sound signal of the front right channel, and mixes the in-phase signal of the rear left channel with the sound signal of the front left channel. The microphone according to claim 1. The reverse phase signal level of each channel to be mixed is set to a level that does not exceed the level of the in-phase signal of each mixed channel within a range of main directivity angles of the plurality of microphone units. The microphone according to claim 1. 2. The four-channel sound signal introducing means includes first to fourth microphone units that have directivity and are arranged so as to be shifted from each other by 90 ° with respect to the central axis. Microphone. The 4-channel sound signal introducing means includes:
Unidirectional first and second microphone units oriented in opposite directions;
A bi-directional third microphone unit oriented in a direction shifted by 90 ° with respect to the direction of the first and second microphone units;
The outputs of the first and third microphone units are added to obtain a front left channel sound signal, the outputs of the first and third microphone units are subtracted to obtain a front right channel sound signal, and the first An arithmetic unit that adds the outputs of the second and third microphone units to obtain a sound signal of the rear left channel, and subtracts the outputs of the second and third microphone units to obtain a sound signal of the rear right channel. The microphone according to claim 1, wherein:

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