JPS6024637B2 - stereo zoom microphone - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a stereo zoom microphone whose directivity can be continuously varied, and in particular, by linking it with the zooming function of a video camera or an 8m/m camera, it can be used to capture images. This makes it possible to collect sound appropriately and match the video and sound image during playback.

FIG. 1 shows a configuration block of an MS (Mid-Side) type stereo microphone.

In Figure 1, 1 is a unidirectional microphone unit (
Mid microphone unit), and the axis of this unidirectional microphone unit is oriented in the X-axis direction. 2
is a bidirectional microphone unit (Side microphone unit), and the axis of this bidirectional unit 2 is at a Z angle different from the axis of the unidirectional unit 1 by 90 degrees.
oriented in the axial direction.

3 and 3' are amplifiers; 4 is an adder that adds the outputs of the amplifiers 3 and 3'; and 5 is a subtracter that subtracts the outputs of the amplifiers 3 and 3'.

In FIG. 1, the X direction is the main axis direction (front direction) of the microphone, and the directivity of the above-mentioned unidirectional unit is generally on a single U board (however, it is a to 1).

Note that a is the direction of the sound source viewed from the X-axis 10a.

On the other hand, the directivity of the bidirectional unit 2 is generally expressed as sin8. The directivities of the output of the adder 4 and the output of the subtractor 5 in FIG. 1 are as follows, respectively.

Note that b is the level ratio during addition and subtraction. Figure 2A
, B, C, and D are point A, point B, and C in Figure 1, respectively.
It shows the directivity pattern of the signal at point and point D (
However, within the xy plane). 2 in Figure 2 C and D
indicate the angle at which the sensitivity of the R channel and the L channel are maximum, respectively, and the angles , and 2 are the wings n4 of the
{t￥2} of 2 knees, and by a and b, the angle of the directional axis is 2 of , .
is determined.

FIG. 3 shows the stereo zoom in one embodiment of the present invention.
A configuration block diagram of a microphone is shown.

The main axis of the microphone in this example is the Z direction. In FIG. 3, 2 is a bidirectional microphone unit,
The axis of this bidirectional unit 2 is different from the main axis by 9 points.

1 is a unidirectional microphone unit, and the axis of this unidirectional unit 1 coincides with the hand axis.

Note that the units 1 and 2 are arranged with a distance d between them. Note that the interval d is d because peaks and valleys occur in the frequency characteristics at high frequencies where d is an integer multiple of the half wavelength of the sound wave.
, the distance is about 300 meters. Reference numeral 6 denotes an iron directional microphone unit such as a super-directional microphone unit, and this unit 6 is arranged at a distance from the center point of the unit 2.

Note that since peaks and valleys occur in the frequency characteristics at high frequencies where an integral multiple of the half wavelength of the sound wave is d3, the interval is preferably about 3 degrees. 7, 7', 7'' are units 2, 1
, 6, an adder 4 that adds the outputs of the amplifiers 7 and 7', and a subtracter 5 that subtracts the outputs of the amplifiers 7 and 7'.

8, 9, 10' are variable resistors that respectively vary the levels of the output of the adder 4, the output of the subtracter 5, and the output of the amplifier 7''. Unlike the resistors 8 and 9, whose resistance value changes similarly and the output level changes as shown in FIG. 4A, the variable resistor 10
is inversely proportional to 8 and 9.

1 1 is an adder that adds the outputs of variable resistors 8 and 10, 12 is an adder that adds the outputs of variable resistors 9 and 10, and the outputs of adders 11 and 12 are variable for volume adjustment. R channel output, L via resistors 13 and 14
This is the channel output.

The variable resistors 13, 14 are the variable resistors 8, 9, 1.
0, and the output level is similarly adjusted as shown in FIG. 4B. 5A to 5E show the directivity patterns of signals at points A, B, C, D, and E of the embodiment shown in FIG. 3.

6A, B and 7A, B show the directivity patterns of the signals at point F and point G when adjusting variable resistors 8 to 10, 13, and 14, respectively. 8-1
When adjusting the variable resistors 0, 13, and 14 to the wide side, the directional pattern becomes wider as shown in Fig. 6A and B, and on the other hand, adjusting the variable resistors 8 to 10, 13, and 14 to the telephoto side. In this case, the width becomes narrower as shown in FIGS. 7A and 7B.

FIG. 8 shows the state of the stereo zoom microphone of the present invention during sound collection.

×, Y, and Z are the sound sources, and M is the stereo zoom microphone of the present invention.As mentioned above, by adjusting the variable resistor, the directivity can be changed continuously from "wide" to "telephoto". 9A.
As shown in , when the left and right speakers S, , S2 reproduce the sound, the sound images of the sound sources ×, Y, and Z ×′, Y, and Z′ are
．． , S2. On the other hand, when the sound is collected by the telephoto J and reproduced by the speakers S, .S2, the sound image Y' of the sound source Y is magnified and localized between the speakers S, , S2. As described above, the stereo zoom microphone of the present invention allows the directivity pattern to be varied continuously, and when the microphone is moved to match the zooming of a video camera or 8h/m camera, it is possible to collect sound that matches the image. be.

The present invention has the above configuration, and according to the present invention, the directivity can be continuously changed with a simple configuration.

[Brief explanation of drawings]

Figure 1 is a block diagram of the M-S type stereo microphone.
Figure 2 A, B, C, and D are signal directivity pattern diagrams at points A, B, C, and D in Figure 1, and Figure 3 is a block diagram of a stereo zoom microphone in an embodiment of the present invention. , Figures 4A and B are characteristic diagrams of the variable resistor used in the same microphone, and Figures 5A, B, C, D, and E are the 3rd resistor characteristics, respectively.
Directivity pattern diagrams of signals at points A, B, C, D, and E in the figure; A, B in Figure 6 and A, B in Figure 7 are diagrams of directivity patterns of signals at points F and G in Figure 3; FIG. 8 is a diagram showing the sound collection state by the stereo zoom microphone of the present invention, and FIGS. 9A and B show the localization of the sound image when the signal collected by the stereo zoom microphone of the present invention is reproduced. It is a diagram. 1...unidirectional microphone unit, 2.
．．・...bidirectional microphone unit, 4...adder,
5... Subtractor, 6... Iron directional microphone unit, 7, 7', 7''... Amplifier, 8, 9,
10...Variable resistor, 11,12...Adder, 13,1
4...Variable resistor. Figure 1 Figure 2 Figure 4 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1 A unidirectional microphone unit and a sharply directional microphone unit arranged along the main axis, a bidirectional microphone unit arranged oriented in a direction 90° different from the main axis, and the unidirectional microphone unit a first adder and a subtracter for adding and subtracting the output of the microphone unit and the output of the bidirectional microphone unit; a first level variable means for varying the output level of the first adder; Adding the outputs of a second level variable means for varying the output level of the subtracter, a third level variable means for varying the output level of the sharply directional microphone unit, and the first and third level variable means. and a third adder that adds the outputs of the second and third level variable means, the first, second and third level variable means are interlocked, and , the level change by the third level variable means is controlled by the first,
A stereo zoom microphone in which the level change by the second level variable means is reversed.