JPH0129356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a directional microphone device using a microphone array.

(Prior art) Microphones with sharp directional characteristics are constructed using microphone array-type microphones in which a plurality of microphone elements are arranged in a desired arrangement, and outputs from individual microphone elements in a microphone array. Research and development has begun on microphone devices that allow the direction of the main lobe to be changed freely by giving a predetermined amount of time delay to each signal, and recently these devices have been put into practical use. It also began to be attempted.

FIG. 1 is a block diagram showing a configuration example of a microphone device in which the direction of the main lobe can be freely changed by giving a predetermined amount of time delay to each output signal from each microphone element in a microphone array. In FIG _. 1, A ₁ , A ₂ . The microphone array MA is configured by arranging the microphones in the following manner.

The output signals from each microphone element A ₁ , A ₂ ...An are transferred to individual changeover switches SW ₁ , SW ₂ ...
Each microphone element A ₁ , A ₂ ...An
are applied to circuits that apply a predetermined amount of time delay to the output signals from the respective output signals.

The aforementioned changeover switches SW _{1 , SW 2} . ~SWn
The movable contacts a are switched all at once to the fixed contacts l or r labeled with the same reference numerals.

A switching control signal applied via the input terminal 1 causes the movable contacts a in each of the changeover switches SW ₁ to SWn to switch between the respective changeover switches SW ₁ to SWn.
When SWn is switched to the fixed contact l side, the output signal of microphone element A ₁ is sent to output terminal 2 without any delay, and the output signal of microphone element A ₂ is The delay circuit D ₁ delays the time τi and sends it to the output terminal 2, and the output signal of the microphone element A ₃ is sent to the output terminal 2 by the delay circuit D _2.
and the delay circuit _D1 , the signal is sent to the output terminal 2 with a delay of time 2τi applied thereto. Similarly, the output signal from microphone element An-2 is processed by (n-3) delay circuits.
The signal is sent to the output terminal 2 with a time delay of τi, and the output signal from the microphone element An-1 is delayed by (n-2) delay circuits.
2) A time delay of τi is given and sent to the output terminal 2, and the output signal from the microphone element An is further delayed by (n-1) delay circuits.
1) Sent to output terminal 2 with a time delay of τi.

As mentioned above, at predetermined equal intervals d approximately on a straight line
The delay times of each of the delay circuits _D1 , _D2 ...D(n-1) used to delay the output signal from each microphone element arranged in are all set to the same value τi. However, when the delay time τi described above is gradually increased from 0, the direction of the main lobe of the microphone array MA becomes orthogonal to the straight line on which the microphone elements A ₁ to An are arranged, Also, from the state facing the front of the microphone array MA (0° state), move 90° to the left along arrow L in the figure showing the movement mode of the main lobe, which is described for reference in FIG. It gradually changes until it is facing the direction of.

Next, each changeover switch is controlled by a changeover control signal.
When _the movable contacts a of SW ₁ to SWn are switched to the fixed contacts r side, each microphone element is
The amount of time delay given to the output signals of A ₁ to An is determined by the amount of time delay given to the output signals of the plurality of microphone elements of the microphone array MA when the movable contacts a of the changeover switches SW ₁ to SWn are switched to the fixed contacts l side.
This is different from the amount of time delay given to each output signal of A ₁ to An. That is, the output signal from the microphone element An in this case is sent to the output terminal 2 without delay, and
The output signal of the microphone element An-1 is sent to the output terminal ₂ after being given a time delay of τi by the delay circuit D1, and in the same manner, the output signal of the microphone element An-2... _A3 , _A2 , A The amount of time delay given to the output signal of ₁ is 2τi..., (n-3)
τi, (n-2)τi, and (n-1)τi.

Then, in a state where the movable contact a of each changeover switch SW ₁ to SWn is switched to the fixed contact r side, the delay time τi of each delay circuit D ₁ to D(n-1) described above is gradually increased from 0. When the direction of _the main lobe of the microphone array MA is changed as shown in FIG. From the condition
The main lobe gradually changes to a state in which it faces 90 degrees to the right along arrow R in the figure showing the movement mode of the main lobe, which is shown for reference in FIG.

Therefore, each changeover switch SW ₁ to SWn is controlled by the changeover control signal supplied via the input terminal.
means for selectively switching the movable contact a to either the fixed contacts l or r, and each delay circuit _D1 to D(n-
By applying 1) the means for varying the delay time τi, the direction of the main lobe of the microphone array MA can be changed as required within a range of 180° in front of the microphone array MA.

FIG. 2 is a block diagram showing an example of the configuration of a delay circuit configured such that the delay time is variably controlled. In FIG. 2, Da to Dd indicate respective delay times. τ, 2τ,
4τ and 8τ, and individual switches S ₁ , S ₂ , S ₃ , and S ₄ are provided between the input and output terminals of each of the delay circuit elements Da to Dd.
is connected.

The delay circuit shown in FIG. 2 has each delay circuit element Da
~ Switch S ₁ connected between the input and output terminals of Dd
The 16 combinations of on and off states of ~ _S4 create a delay circuit that exhibits 16 delay times. In other words, when all switches S ₁ to _{S 4} are on, the delay circuit has a delay time of 0.
In addition, when only switch S ₁ is off, the delay circuit has a delay time of τ, and when only switch S ₂ is off, the delay circuit has a delay time of 2τ, and so on. To,
Depending on the on/off combination of switches _S1 to _S4 , the delay time of the delay circuit is 0, τ, 2τ, 3τ, 4τ.
...It can be changed in 16 steps like 15τ.

The on/off control of the four switches _S1 to _S4 described above is easily performed by a delay amount control signal in the form of a 4-bit digital signal applied to the delay circuit via the line _l2 . Naturally, if the delay circuit is constructed using a larger number of delay circuit elements than the delay circuit shown in FIG. 2, the number of switchable delay times in the delay circuit can be increased.

Assuming that the delay time τi in each delay circuit _D1 to D(n-1) is changed in 16 steps as described above,
This, in combination with the left and right switching action by the switching control signal applied to input terminal 1 via line _l1 , allows the main lobe of microphone array MA to be oriented within 180° in front of the microphones. It will be changed in the direction of 31.

i.e. via the line l ₁ to the changeover switch SW ₁ ~
A 1-bit switching control signal given to SWn,
The 4-bit delay amount control signal given to the delay circuits _D1 to D(n-1) via the line _l2 is the angle at which the main lobe of the microphone MA is set within a range of 180° in front of the microphone MA. It determines where it will occur.

The switching control signal and delay amount control signal described above are
Generated in the control signal generation circuit CSG,
This control signal generation circuit CSG can easily generate a required control signal if it is configured to include, for example, a microcomputer.

In the example shown in the first diagram, the controller CR is composed of a variable resistor VR and an analog-to-digital converter A/D, and the operator
Microphone array MA by adjusting VR slider
Sets the orientation of the main lobe of.

By adjusting the slider described above, a voltage between the +B voltage and the ground voltage appears on the slider of the variable resistor VR, and the voltage obtained at the slider is applied to the analog-to-digital converter A. /D performs analog-to-digital conversion so that the entire range of voltage change in the slider corresponds to an appropriate value, for example 256, and the analog-to-digital converter A/D outputs the voltage of the slider of the variable resistor VR. An 8-bit main lobe direction indicating signal corresponding to the position is generated and applied to the control signal generating circuit CSG described above.

Now the variable resistor VR in the controller CR
Microphone array
It corresponds to the change range of the direction of the main lobe of the microphone array MA over a range of 180° in front of the MA, and also corresponds to the displacement of the slider of the variable resistor VR over the entire adjustment range. Accordingly, the voltage value appearing on the slider is given to the control signal generation circuit CSG as an 8-bit main lobe direction indication signal by the analog-to-digital converter A/D, and furthermore, the voltage value appearing on the slider is given to the control signal generation circuit CSG as an 8-bit main lobe direction indication signal. Delay circuits _{D1 to} D(n-
An example configuration of the control signal generation circuit CSG described above will be explained by taking as an example a case in which the delay time τi in 1) is controlled to be switched in 16 steps by a 4-bit switching control signal. do.

By adjusting the slider of the variable resistor VR of the controller CR, the operator can adjust the microphone array MA.
The direction of the main lobe is perpendicular to the front center of the microphone array MA (the straight line where microphone elements A ₁ to An are arranged), and the main lobe is facing in front of the microphone array MA...This is the direction of the main lobe. is 0°), the position of the slider of variable resistor VR in controller CR is at the center of the range of change of the slider of variable resistor VR, and in this case, The numerical value indicated by the output digital signal from the analog-to-digital converter A/D is 128.

By the way, each delay circuit D ₁ to D(n
Since it is necessary to set the delay signal τi in -1) to 0, the microphone array is
In the control signal generation circuit CSG, each of the delay circuits D ₁ to D (n-1)
A 4-bit delay amount control signal that can bring the delay time τi of
A delay amount control signal is generated to turn on all the switches _S1 to _S4 . When the main lobe direction of microphone array MA is 0°,
The movable contacts a of the changeover switches SW ₁ to SWn may be connected to either the fixed contacts l or r, so
In this case, the switching control signal may be set so that the movable contact a is switched to a predetermined one of the fixed contacts l and r.

By adjusting the slider of the variable resistor VR of the controller CR, the direction of the main lobe of the microphone array MA can be set within the ranges of 90° to the right from the 0° direction and 90° to the left from the 0° direction. is set. Therefore, if the value indicated by the 8-bit main lobe direction indication signal generated by the analog-to-digital converter A/D corresponding to the adjustment position of the slider of the variable resistor VR of the controller CR is between 1 and 128. For example, on the left
Corresponds to the range from 90° orientation to 0° orientation,
In addition, if the numerical value indicated by the above-mentioned 8-bit main lobe direction indication signal is 128 to 256, it should be made to correspond to the range from, for example, 0° to 90° to the right, and the above-mentioned Analog digital converter A/
If the direction of the main lobe indicated by the numerical value of the 8-bit output digital signal from D is, for example, θ° to the left, the control signal generation circuit CSG selects the changeover switch.
Create a switching control signal that switches the movable contacts a of SW ₁ to SWn to the fixed contact l side, and connect it to the wire.
A delay amount control signal is applied to the changeover switches _SW1 to SWn via line _l1 , and a delay amount control signal is generated so that the direction of the main lobe is θ°, and the signal is sent to the delay circuit via line _l2 .
If the direction of the main lobe, which is applied to D ₁ to D(n-1) and is represented by the numerical value of the 8-bit output digital signal from the analog-to-digital converter A/D described above, is, for example, right α°, then the control The signal generating circuit CSG generates a switching control signal that switches the movable contacts a of the changeover switches SW ₁ to SWn to the fixed contact r side, and sends it to the changeover switches SW _{1 to} SWn via the line l1.
In addition, a delay amount control signal can be created so that the direction of the main lobe is α°, and can be applied to the delay circuits _D1 to D(n-1) via the line _l2 . In the control signal generation circuit CSG, a required switching control signal and a required delay amount control signal are generated based on the main lobe direction indication signal sent from the controller CR, and these are connected to the lines l ₁ and l ₂ . It is clear that the main lobe of the microphone array MA is oriented as set by the operator by adjusting the slider of the variable resistor VR of the controller CR.

(Problems to be Solved by the Invention) Now, in the microphone device configured as described above, the main lobe of the microphone device can be set in front of the microphone array MA by adjusting the slider of the variable resistor VR of the controller CR. Although it can be set to point in any desired angular direction within a range of 180°, in the directivity characteristics of the microphone array MA, which is constructed using multiple microphone elements, the main lobe is oriented in the 0° direction, i.e. , the directional characteristics of the microphone array MA when it is configured to face the front of the microphone array MA are as shown in FIG. For example, in the case of a so-called cardioid, as shown in a of FIG. 4, and in the case of a so-called hypercardioid, as shown in a of FIG. becomes.

As is clear from FIG. 3 a and b and FIG. 4 a and b, the main lobe (front lobe) in the microphone array is larger than the main lobe (front lobe) in the microphone element. However, the front lobe of a microphone array becomes increasingly sharp as the number of microphone elements used to construct the microphone array increases.

However, when looking at the front-to-back sensitivity ratio of the microphone array as a whole, it is found that it is the same as the front-to-back sensitivity ratio of the microphone elements used to configure the microphone array.

Also, the direction of the front lobe is
The 0° direction shown in figure b, that is, within the range of 90° to the right (or left) from the front of the microphone array MA {within the range of 90° clockwise (or counterclockwise) from the 0° direction }, the directional characteristics of the microphone array MA change to states as shown in c, d, e in FIG. 3 and c, d, e in FIG. 4.

In other words, when the direction of the main lobe of the microphone array MA is tilted in the 0° direction, that is, in the clockwise (or counterclockwise) direction from the front of the microphone array MA, the line 90° −
A rear lobe is generated at a mirror-symmetrical position about 270°.

The above-mentioned main lobe (front lobe) and rear lobe are the directional characteristic curves (indicated by dotted lines in b to e in Figure 3 and b to e in Figure 4) of the microphone elements constituting the microphone array MA. The main lobe (front lobe) rotates clockwise (or counterclockwise) from the 0° direction.
When the direction is changed within a range of 90°, as the angle β increases, the ratio of the sizes of the front lobe and the rear lobe decreases.
Therefore, when the direction of the front lobe (main lobe) of the microphone array is gradually tilted from the 0° direction, a problem arises in that the directivity of the microphone array MA becomes substantially dull.

(Means for Solving the Problems) The present invention uses a microphone element having unidirectionality as a microphone element constituting a microphone array, and uses a straight line toward the front of the microphone array within a plane including the main axis of the microphone element. A microphone element whose main axis is tilted by an angle θ within 90° clockwise with respect to the reference line, and a microphone element whose main axis is tilted by an angle θ within 90° with respect to the reference line, and a microphone element whose main axis is tilted clockwise with respect to the reference line. A microphone array is constituted by a plurality of microphone element pairs, each pair being a microphone element whose main axis is tilted by an angle θ within 90° in the opposite direction. When the direction of the lobe is oriented clockwise within 90 degrees with respect to the above reference line, each microphone element pair making up the microphone array is oriented counterclockwise with respect to the above reference line. A microphone array consisting only of microphone elements whose principal axes are inclined at an angle θ in the circumferential direction is used, and the direction of the main lobe of the microphone array is 90 degrees with respect to the reference line mentioned above. When the main axis of each microphone element pair constituting the microphone array is tilted clockwise by an angle θ with respect to the reference line described above, By using a microphone array consisting only of elements, the rear lobe in the microphone array is generated near the insensitive part of the directivity of the microphone element, and the rear lobe in the microphone array is eliminated or has achieved a significant reduction.

(Example) FIG. 5 is a block diagram of an embodiment of the directional microphone device of the present invention, and in FIG. 5, components corresponding to those in the microphone device shown in FIG. The same drawing numerals as those used in FIG. 1 are used.

In Fig. 5, A ₁ l, A ₂ l, A ₃ l...Anl indicates that the microphone array MA has its main lobe (front lobe) directed in the 0° direction, that is, in the direction in front of the microphone array. n microphone elements with unidirectionality used as a microphone array when changing the angle within 90 degrees counterclockwise from
A ₁ r, A ₂ r, A ₃ r…Anr is the microphone array
An MA is used as a microphone array when the direction of its main lobe (front lobe) is to be varied within an angular range of 90° clockwise from the 0° direction, i.e. the direction in front of the microphone array. The above-mentioned 2n microphone elements are n microphone elements having unidirectionality, and the microphone elements A ₁ l and A ₁ r are 1
In such a manner that a pair of microphone elements is configured, and microphone elements A ₂ l and A ₂ r are configured as a pair of microphone elements, a total of n This constitutes a microphone element pair.

2n microphone elements in a microphone array MA in which n microphone element pairs are configured by a total of 2n microphone elements.
A ₁ l, A ₁ r, A ₂ l, A ₂ r...Anl, Anr are arranged so that each microphone pair is arranged on a straight line on the same plane with a predetermined interval apart, or
As shown in the figure, each microphone pair is arranged on a circular arc on the same plane at a predetermined interval, or as shown in the seventh figure, each microphone pair is arranged on a broken line on the same plane at a predetermined distance. They may be placed at intervals of . The arrangement shown in Figures 6 and 7 prevents the directivity characteristics at high frequencies from becoming too sharp even when the main lobe is oriented at a large angle from the 0° direction. It is effective for

The n microphone element pairs constituting the microphone array MA are required to be spaced apart by a distance d that is shorter than a half wavelength of the sound at the upper limit frequency in the frequency range targeted for sound collection in the microphone array MA. However, depending on the size of the microphone elements used, there may be cases where it is not possible to arrange the microphone element pairs at the distance d described above.

In such a _case , as _shown in the plan view of FIG.
and microphone elements A ₁ r, A ₂ r...Anr arranged in separate rows, respectively, may be arranged offset in a direction perpendicular to the direction in which the microphone elements are arranged, or alternatively, the perspective view of Fig. 9 may be arranged. Each pair of microphone elements is shown in
Anr, Anl, A(n-1)r, A(n-1)l,...
The arrangement may be such that A ₁ r and A ₁ l are stacked vertically.

Each microphone element with unidirectionality in the microphone array MA A ₁ l, A ₂ l...Anl, A ₁ r,
Microphone element A ₁ l, A ₂ l… within A ₂ r…Anr
Anl is an angle within 90° clockwise in a plane that includes the principal axis of each microphone element, with the straight line facing the front of the microphone array (the straight line indicating the 0° direction) as the reference line. The main axis is inclined by θ, and each microphone element A ₁ r, A ₂ r...Anr is arranged in a straight line (0 The main axis is inclined by an angle θ within 90° in the counterclockwise direction when the reference line is a straight line indicating the direction of 90°.

The angle θ at which the main axis of the microphone element is tilted clockwise or counterclockwise with respect to the reference line depends on the shape of the directional characteristics of the microphone element with unidirectionality used in the configuration of the microphone array. Is there a microphone array?
It should be determined depending on the angle range in which the direction of the main lobe is to be changed in MA, etc. Next, how to determine the angle θ described above with reference to Fig. 10. and a microphone array MA configured using microphone elements whose principal axes are tilted by an angle θ as described above.
We will explain the directional characteristics of.

FIG. 10 shows an example in which the microphone elements used in the configuration of the microphone array MA have a cardioid directivity characteristic as shown in FIG. FIG. 2 is a reference diagram for explaining points such as what angle of inclination θ should the main axis of the microphone element be inclined with respect to the front of the microphone array when configuring the microphone array.

A ₁ r (~Anr) in the diagram shown in Figure 10 a is a microphone element shown for reference, and A ₁ l (~Anl) in the diagram shown in Figure 10 b
is also a microphone element shown for reference, and is indicated by dotted lines in a of FIG. 10 and b of FIG. 10.
Kr−Kr and Kl−Kl are the principal axes of the microphone elements A ₁ r (~Anr) and A ₁ l (~Anl), respectively,
Microphone element A ₁ r~ with unidirectional characteristics
Anr has a cardioid directivity characteristic as shown by the imaginary line Ra in a in Fig. 10, and a microphone element A ₁ l (~Anl) has a unidirectional directivity characteristic.
has a cardioid directivity characteristic as shown by the imaginary line Lb in FIG. 10b.

In FIG. 10a and FIG. 10b, the line - is the direction in which the microphone elements are arranged in the microphone array MA, and the 0° direction in the figures indicates the front direction of the microphone array MA.

Microphone element A ₁ r (~
Anr), the direction of its principal axis Kr−Kr is tilted counterclockwise by an angle θ with respect to the direction in front of the microphone array MA, that is, the 0° direction, and In the microphone element A ₁ l (~Anl) shown in , the direction of its principal axis Kl−Kl is tilted clockwise by an angle θ with respect to the direction in front of the microphone array MA, that is, the 0° direction. Therefore, for example, as in the microphone element A ₁ r (~Anr) shown in Figure 10a, the direction of its principal axis Kr−Kr is counterclockwise with respect to the front direction of the microphone array. Microphone element A ₁ r~ tilted by θ degrees
When using a microphone array configured with an array of Anr and changing the direction of its main lobe over a range of 180° in front of the microphone array, the main lobe of the microphone array becomes
In the curve Ra shown in Figure 10 a -
The size changes along the part above the line, and the direction of its principal axis Kl−Kl, as in the microphone element A ₁ l (~Anl) shown in Fig. 10b. Using a microphone array configured by an array of microphone elements A ₁ l to Anl, which are tilted by θ degrees in a clockwise direction with respect to the front direction of the microphone array,
When the direction of its main lobe is changed over a range of 180° in front of the microphone array,
The main lobe of the microphone array is b in Figure 10.
The size changes along the portion above the - line in the curve Lb shown in .

By the way, in the microphone array, the rear lobe is generated at a position mirror-symmetrical to the main lobe (front lobe) with the - line as the axis of symmetry, as already mentioned in the explanation of FIGS. 3 and 4. If a rear lobe that occurs at a position mirror-symmetrical to the front lobe with the - line as the symmetry axis is located in an insensitive region of the microphone element, the rear lobe will not actually appear.

Therefore, in the directional microphone device of the present invention, the rear lobe, which occurs at a mirror-symmetrical position with respect to the front lobe within the moving range of the front lobe, is located near the insensitive region of the microphone element, with the - line as the axis of symmetry. So that
The rear lobe can be eliminated or This resulted in a significant reduction. Note that when the arrangement of the microphone elements is as shown in FIGS. 6 and 7, the angle θ may be determined with a direction orthogonal to the direction in which the microphone elements are arranged as a reference direction.

That is, in the directional microphone device of the present invention, the direction of the front lobe is changed clockwise from the direction in front of the microphone array (0° direction).
The microphone array used to change the angle within a range of 90 degrees, that is, the direction of the principal axis Kr-Kr is rotated counterclockwise from the direction in front of the microphone array (0 degree direction), as shown in Figure 10a. Microphone element tilted by the required angle θ in the direction
A ₁ A microphone array configured using r~Anr and the direction of the front lobe counterclockwise from the front direction of the microphone array (0° direction).
A microphone array used to change the angle within a range of 90 degrees, that is, the direction of the principal axis Kl-Kl is rotated clockwise from the front direction of the microphone array (0 degree direction), as shown in Figure 10b. A microphone array constructed using microphone elements A ₁ l−Anl tilted by a required angle θ in the direction of By switching the usage according to the range of change, the rear lobe can be eliminated,
Or, a significant reduction has been achieved.

A microphone array used to change the direction of the front lobe of the microphone array within an angular range of 90° clockwise from a reference line indicating the direction in front of the microphone array (0° direction). Configuring microphone element A ₁ r
~Anr, as shown in Figure 10 a,
The above-mentioned microphone is element
A ₁ For a microphone array configured using r~Anr, the front lobe of the microphone array is calculated when the direction of the front lobe is changed within an angle range of 90° clockwise from the reference line. The size changes according to the curve between the straight line 0-0° and the straight line 0-90° within the curve Ra shown by the imaginary line in Figure 10a, and, A microphone array used to change the direction of the front lobe of a microphone array within an angular range of 90° in a counterclockwise direction from a reference line indicating the direction in front of the microphone array (0° direction). Microphone element A ₁ l~
As shown in Figure 10b, Anl has its principal axis Kl-Kl clockwise with respect to the reference line indicating the front direction (0° direction) of the microphone array. By being tilted by the required angle θ, the aforementioned microphone element A ₁ l
~The size of the front lobe of a microphone array configured using Anl when the direction of the front lobe is changed within an angle range of 90° counterclockwise from the reference line. is the curve shown as an imaginary line in Figure 10b.
Within Lb, it changes according to the curve between the straight line 0-0° and the straight line 0-270°.

Then, the front lobe is changed in size and direction according to the curve between the straight line 0-0° and the straight line 0-90° in the curve Ra shown in Figure 10a. When the axis of symmetry is the - line, the rear lobe that should occur at a position mirror-symmetrical to the front lobe is the insensitivity of the microphone elements A ₁ r to Anr between the straight line 0-90° and the straight line 0-180°. It does not occur in the part of , and only when the forward lobe is oriented at an angle close to 90 degrees clockwise from the reference line, it will occur with a magnitude that follows the curve Ra.

In addition, the front lobe is changed in size and direction according to the curve between the straight line 0-0° and the straight line 0-270° in the curve Lb shown in Fig. 10b. The rear lobe that should be generated at a position mirror-symmetrical to the front lobe with the _- line as the axis of symmetry is the It does not occur in some parts, and only when the forward lobe is oriented at an angle close to 90° counterclockwise from the reference line, it will occur with a magnitude that follows the curve Lb.

In the examples shown in Figures 10a and 10b, the rear lobe is generated when the front lobe is oriented at an angle close to 90 degrees from the reference line. , This is an example of a case where the tilt angle θ of the microphone element is determined even on the - line in order to make it possible to vary the direction of the front lobe in the microphone array up to an angle of 90 degrees from the front of the microphone array. This is why, in implementation, corresponding to a predetermined movement range of the direction of the front lobe, so that a state in which no rear lobe is generated is achieved.
Of course, the inclination angle θ of the microphone element may be set.

In the directional microphone device of the present invention shown in FIG. 5, the microphone elements A ₁ l to Anl in the microphone array MA have the front lobes of the microphone array directed within 90 degrees counterclockwise from the front direction of the microphone array. It constitutes a microphone array used when trying to change the angle in the angular range of A1 _r to Anr in the microphone array MA.
is the direction of the front lobe of the microphone array,
The microphone array is used when changing the angle within 90 degrees clockwise from the front direction of the microphone array, so the direction of the front lobe (main lobe) of the microphone array MA is in front of the array
In order to change within the range of 180°, it is necessary to switch the movable contacts a of the changeover switches SW ₁ to SWn to the fixed contact l side and the fixed contact r side,
This takes place in the same manner as in the first illustration described above, by means of a switching control signal which is supplied to input terminal 1 via line _l1 .

In addition, the switching control signal described above and the delay circuit D ₁
A control signal generation circuit for generating a delay amount control signal to be applied to ~D(n-1) via line _l2
The configuration and operation of the CSG, the controller CR consisting of the variable resistor VR and the analog-to-digital converter A/D, etc. are also as explained with reference to FIG.

(Effects) As is clear from the detailed explanation above, the directional microphone device of the present invention has the advantage that the directional microphone device of the present invention has the advantage of providing the following effects: By varying the respective predetermined delay amounts to be given to the output signals individually,
In a directional microphone device in which the direction of the main lobe can be freely changed while keeping the spatial position of the microphone itself constant, it is possible to eliminate or significantly eliminate the rear lobe that occurs at a position mirror-symmetrical to the front lobe. In order to reduce the amount of light, a microphone array is constructed using microphone elements whose principal axes are tilted by a required angle θ in a clockwise direction from the front of the microphone array, and a microphone element whose principal axis is tilted by a required angle θ clockwise from the front of the microphone array, and a microphone element whose main axis is tilted by a predetermined angle θ clockwise from the front of the microphone array. A microphone array composed of microphone elements whose principal axes are inclined by a required angle θ in the surrounding direction is provided, and the direction of the front lobe of the microphone array is within 90° from the direction in front of the microphone array. When the microphone is oriented in a counterclockwise direction, a microphone array composed of microphone elements whose principal axes are tilted by a required angle θ clockwise from the direction in front of the microphone array is used. and when the direction of the front lobe of the microphone array is oriented in a clockwise direction within 90° from the direction in front of the microphone array, the required angle θ in the counterclockwise direction from the direction in front of the microphone array. This has been realized by applying an extremely simple means of using a microphone array constituted by microphone elements whose principal axes are inclined by . An excellent directional microphone device can be easily provided.

[Brief explanation of drawings]

Figure 1 is a block diagram of the microphone device, Figure 2
The figure is a block diagram of an example configuration of a delay circuit, FIGS. 3 and 4 are directional characteristic curve diagrams, FIG. 5 is a block diagram of an embodiment of the directional microphone device of the present invention, and FIGS. 6 to 9 The figure is a diagram for explaining the arrangement of microphone elements, and FIG. 10 is a diagram for explaining the state of inclination of the microphone elements constituting the microphone array in the apparatus of the present invention. MA……Microphone array, A ₁ ~ An, A ₁ r
~Anr, A ₁ l~Anl……Microphone element, SW ₁
~SWn...Changing switch, _D1 ~D(n-1)...
Delay circuit, CSG...control signal generation circuit, CR...
controller.

Claims (1)

[Claims] 1. In a microphone array formed by arranging a plurality of microphone elements having unidirectionality, a predetermined amount of delay to be individually given to the output signal from each microphone element is varied, and the space of the microphone itself is In a directional microphone device in which the direction of the main lobe can be freely changed while the main lobe remains constant, the microphone array is A microphone element whose main axis is inclined by an angle θ within 90° clockwise with respect to the reference line, and a microphone element whose main axis is tilted by an angle θ within 90 degrees with respect to the reference line, with the straight line facing the front as the reference line. A microphone array is constituted by a plurality of pairs of microphone elements, each pair being a microphone element whose main axis is tilted by an angle θ within 90 degrees in the counterclockwise direction, and the main lobe of the microphone array is is oriented in a clockwise direction within 90 degrees with respect to the above-mentioned reference line, in each microphone element pair making up the microphone array, the direction is counterclockwise with respect to the above-mentioned reference line. A microphone array consisting only of microphone elements whose principal axes are inclined by an angle θ is used, and the direction of the main lobe of the microphone array is within 90° counterclockwise with respect to the reference line mentioned above. When facing in the circumferential direction, each microphone element pair constituting the microphone array is composed of only microphone elements whose principal axes are inclined by an angle θ in a clockwise direction with respect to the reference line described above. A directional microphone device using a microphone array.