JP2005322953A - Microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a 4-channel microphone capable of providing senses of spread and presence even when the microphone is connected to a 2-channel acoustic apparatus. <P>SOLUTION: Sound signals FL1, FR1, RL1, RR1 picked up by a 4-channel microphone unit are received from input terminals 21<SB>I</SB>to 24<SB>I</SB>. When a 4-channel acoustic apparatus is connected to the 4-channel microphone unit, a changeover switch 15 is opened and the input signals are output as 4-channel sound signals FL, FR, RL, RR. When a 2-channel acoustic apparatus is connected to the 4-channel microphone unit, the changeover switch 15 is closed and a left channel sound signal L resulting from mixing an inverted signal (by RR2) of the rear right sound signal and a noninverted signal (by RL1) of the 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 L resulting from mixing an inverted signal (by RL2) of the rear left sound signal and a noninverted signal (by RR1) of the rear right sound signal to the front right sound signal FR1 is output to an output terminal 22<SB>O</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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.

Also, as described in Patent Document 2 below, a so-called MS system that obtains a 4-channel audio signal using two unidirectional microphone units and one bidirectional microphone unit. A microphone has been proposed.
Japanese Patent Laid-Open No. 5-191887 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.

  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. An object of the present invention is to provide a microphone that can provide a sense of spaciousness and realism by effectively using the.

  In the 2-channel playback of 2-channel audio equipment, in order to obtain a sense of breadth and presence, it has been 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.

  As described above, the method of obtaining a sense of spread and presence in two channels is a method of processing a two-channel sound source.

  On the other hand, in the present invention, among the four-channel sound sources (front left / right, rear left / right), the sound source of the left / right rear two channels is processed as described above and added to the two channels of front / left / right, thereby generating the sound source of four channels. It is configured to be able to express both the sense of expanse and presence more effectively than the method using two channels as a sound source effectively.

  That is, the present invention has a plurality of microphone units, 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. It comprises a 2-channel signal circuit to be created and output, and switching means for switching the output of the 4-channel sound signal and 2-channel sound signal.

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

  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 reverse phase signal of the rear left channel introduced from a plurality of microphone units with the sound signal of the front right channel, and converts the reverse phase signal of the rear right channel to the front left channel. A 2-channel sound signal is created and output by mixing with the sound signal. As a result, two-channel reproduction is performed.

  At this time, since the sound of the reverse phase of the rear left channel is mixed in the front right channel, and the sound of the reverse phase of the rear 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. Furthermore, since the mixed-phase sound sources are recorded from the rear, it becomes 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. 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, since the level of the mixed anti-phase signal does not exceed the level of the mixed in-phase signal, the left rear sound is forward right, the right rear It is reliably prevented that the sound is localized left frontward and the sense of direction is impaired.
(3) According to the invention described in claim 5, 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.
(4) According to the invention described in claim 6, 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 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. 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 act 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 operates when the changeover switch 15 is closed (when the 2-channel audio equipment use mode is selected), and the 2-channel sound signals L, R from the 4-channel sound source recorded by the directional microphone units 11-14. Create and output. 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 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 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 , is connected to one end of a level adjusting resistor 26RL1, and is connected to an input terminal of an inverting amplifier 27RL that inverts the phase.

The input terminal 24 _I is connected to the output terminal 24 _O , is connected to one end of a level adjusting resistor 26RR1, and is connected to an input terminal of an inverting amplifier 27RR that inverts the phase.

  The output terminal of the inverting amplifier 27RL is connected to one end of the level adjusting resistor 26RL2, and the output terminal of the inverting amplifier 27RR is connected to one end of the level adjusting resistor 26RR2.

  A common connection point between the other ends of the resistor 26RL1 and the resistor 26RR2 is connected to the other input end 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 26RL2 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 RR2 whose level is adjusted by the phase inversion resisting 26RR2 by inverting amplifier 27RR a rear right audio signal RR1 input from the input terminal 24 _I, 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 (RR2 minutes) of the rear 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 RL2 whose level is adjusted by the phase inversion resisting 26RL2 by inverting amplifier 27RL the rear left audio signal RL1 input from the input terminal 23 _I, a rear right audio signal RR1 input from the input terminal 24 _I 26RR1 The in-phase signal whose level has been adjusted in (5) is applied to the adder 25R via the contact 15R.

For this reason, the output terminal 22 _O has a right channel sound signal obtained by mixing the front right audio signal FR1 with the reverse phase signal (RL2 minutes) of the rear left audio signal and the in-phase signal (RR1 minutes) of the rear right audio signal. 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 mixed anti-phase signals RL2 and RR2 are recorded from the rear, so that the presence is more realistic.

  Note that the levels of the anti-phase signals RL2 and RR2 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.degree. The resistors 26RL1 and 26RR1 are adjusted so as not to exceed the level of the in-phase signal of the mixed channels.

  Next, 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 RL2 and RR2 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 ° on the left and right.

  That is, in the R channel, the in-phase signal level of 115 ° is 2.0> 245 °, the in-phase signal level is 2.05, the in-phase signal level of 120 ° is 2 = 240 °, and the in-phase signal level is 2 The in-phase signal level of 125 ° is 1.8 <235 °, and the anti-phase signal level is 1.9.

  In the L channel, the in-phase signal level of 245 ° is 2.2> 115 °, the in-phase signal level is 2.05, the in-phase signal level of 240 ° is 2 = 120 °, and the in-phase signal level is 2. The in-phase signal level at 235 ° is 1.8 <125 °, and the anti-phase signal level is 1.9.

  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 of 120 ° is 2> 240 ° and the in-phase signal level is 1.5, and the in-phase signal level of 160 ° is 0.75> 200 ° and the in-phase signal level is 0. .7.

  In the L channel, the in-phase signal level of 240 ° is 2> 120 ° and the in-phase signal level is 1.5, and the in-phase signal level of 200 ° is 0.65> 160 ° and the in-phase signal level 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 3.1 <270 ° and the out-of-phase signal level is 3.2, and the 100 ° in-phase signal level is 2.8 <260 °. 3.3, the in-phase signal level at 160 ° is 2.2, and the reverse phase signal level at 0.25 <200 ° is 2.2.

  In the L channel, the in-phase signal level of 270 ° is 3.1 <90 °, the in-phase signal level is 3.2, and the in-phase signal level of 260 ° is 2.8 <100 °. 3.3, the in-phase signal level at 200 ° is 2.1, and the reverse phase signal level at 0.2 <160 ° is 2.1.

  In the present invention, when the two-channel sound signals L and R are generated from the four-channel audio signals FL1, FR1, RL1 and RR1, the in-phase components RL1 and RR1 of the rear left and right channels are mixed as shown in FIG. You may comprise so that it may not. That is, in FIG. 7, the resistors 26RL1 and 26RR1 of FIG. 3 connected to the adders 25L and 25R are removed, and the other parts are configured in the same manner as in FIG.

  In FIG. 7, when a 4-channel audio device is connected, the operation is the same as in FIG. If the changeover switch 15 is closed when the two-channel audio equipment is connected, only the reverse phase signals RR2 and RL2 obtained by inverting the phase of the rear right and left audio signals RR1 and RL1 to the front left and right audio signals FL1 and FR1, respectively. The signals are added and output as 2-channel sound signals L and R.

Therefore, the sound reproduced by the two-channel audio device 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, as in FIG. The sound localization is blurred and the left and right speakers are spread. Further, since the mixed anti-phase signals RL2 and RR2 are recorded from the rear, it becomes more realistic.

  According to the circuit of FIG. 7, the circuit configuration is simplified and the number of parts can be reduced as compared with the circuit of FIG. 3.

  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 in which the present invention is applied to an M-S (Mid-Side) type microphone provided with a bi-directional third microphone unit will be described with reference to FIG.

  In FIG. 8, 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 (arithmetic unit of the present invention) adds and subtracts the outputs of the three microphone units 31 to 33 to obtain 4 for front left (FL), front right (FR), rear left (RL), and rear right (RR). Get channel audio signal. 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. 3 or FIG. The microphone 30 shown in FIG. 8 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 acts to create and output 2-channel sound signals L and R from the 4-channel audio signals calculated by the encoder 2 in the same manner as the operations described in FIGS. At this time, the sound signals RL and RR of the rear left channel and the rear right channel are not used.

  Also in the microphone 30 of FIG. 8, the balance between the in-phase signal and the in-phase signal of the 2-channel sound signals L and R (pseudo 4-channel stereo) of the present invention created by mixing the anti-phase signals RL2 and RR2 is the same as that shown in FIG. The pattern is the same as in FIGS.

  The 2-channel signal circuit that generates and outputs a 2-channel sound signal from the 4-channel sound signal according to the present invention is not limited to the use of the inverting amplifiers 27RL and 27RR and the resistors 26RL2 and 26RR2, but the rear left and right audio signals RL1. , RR1 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.

  Further, the rear left and right audio signals RL1 and RR1 may be added to the differential amplifier, the output level thereof may be adjusted, the phase delayed, and added to the front left and right audio signals FL1 and FR1, respectively.

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 circuit diagram which shows the other embodiment example of the principal part 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, 26RL2, 26RR2 ... resistors, 27RL, 27RR ... inverting amplifiers, 30 ... microphones, 31 ... unidirectional first microphone unit, 32 ... unidirectional first 2 microphone units, 33... Bidirectional third microphone unit.

Claims (6)

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 2-channel signal circuit for generating and outputting a 2-channel sound signal from the 4-channel sound signal input by the 4-channel sound signal introducing means;
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 reverse phase signal of the rear left channel with the sound signal of the front right channel and mixes the reverse phase signal of the rear right channel with the sound signal of the front left channel. The microphone according to claim 1. The two-channel signal circuit has 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. The microphone according to claim 2. 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 3. 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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