JP2001237975A - Loudspeaker type calling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm the degree of internal echo from an external speaking person by canceling the occurrence of howling through the use of a simple device. SOLUTION: A planar speaker 15 and a window 10 are arranged on an acoustically separated wall K1, microphones 11 and 12 are independently disposed in the front and rear parts of the wall K1 and a mixer 13 for adding the outputs of the both microphones and an amplifier 14 for amplifying the outputs from the mixer 13 to drive the planar speaker are arranged. The speaker 15 is symmetrical in the front and rear parts and also provided with a directional characteristic in the normal area of a speaker surface. Then the microphones on the front and rear parts of the wall K1 are positioned in areas with little sound wave of the planar speaker and, in addition to it, the sound wave of an equal amplitude reverse phase radiated from the front and rear parts of the speaker are added by the mixer and cancelled even when they are respectively inputted to the microphones so that howling is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker system, and more particularly to a loudspeaker system installed at an acoustically isolated window.

[0002]

2. Description of the Related Art Conventionally, when a speaker in a room and a speaker outside have a conversation through a window provided on the wall with a wall acoustically isolated from the outside, a speaker and a microphone are mounted on the wall. A conversational conversation is held with a loudspeaker-type communication device provided. As shown in FIG. 4, the loudspeaker-type communication apparatus includes an external device 2 provided on an outer surface of a wall K2 for acoustically isolating a room R2 from the outside.
The external device 29 includes a microphone 21 and a speaker 2
8 are provided. The microphone 21 is connected to the room R via a microphone amplifier 22 and a speaker amplifier 23 provided in the room R2.
Receiver 2 of the headset worn by speaker H22 in 2
4 is connected. The microphone 25 of the headset worn by the speaker H22 is connected to the speaker 28 of the external device 29 via the microphone amplifier 26 and the speaker amplifier 27. In such a loudspeaker-type communication apparatus, the internal speaker voice S25 of the speaker H22 in the room R2 is amplified by the microphone amplifier 26 to become a microphone output signal S26, and the speaker amplifier 27 outputs the speaker amplifier output signal S27 for driving the speaker 29. And the audio signal S from the speaker 28
281 is output.

On the other hand, the external speaker's voice S21 of the speaker H21 outside the wall K2 is input to the microphone 21 of the external device 29, amplified by the microphone amplifier 22, and converted into a microphone output signal S22. And an audio signal is output from the receiver 24.

[0004] Here, in the speaker H21, the speaker H21
Of the speaker H21 is output from the microphone 2 of the room R2 when the sound of the speaker H21 is emitted by the loudspeaker toward the room R2.
When the sound is picked up by the speaker 5, its own sound is emitted from the speaker 28 of the external device 29, that is, howling occurs. In order to prevent this howling from occurring, the room R
In 2, the conversation is performed using the receiver 24 of the headset worn by the speaker H22 without using the speaker so that the microphone 25 does not pick up the voice of the external speaker H21.
Further, as a conventional loudspeaker apparatus which prevents howling from occurring without using such a headset, FIG.
As shown in the figure, the wall K that acoustically isolates the room R3 from the outside
3 is provided with an external device 31 provided on the outer surface and an internal device 32 provided on the inner surface. The external device 31 is provided with a microphone 311, a microphone amplifier 312, and an echo canceller 313 in that order.
3, a speaker amplifier 314 connected to the speaker amplifier 314 and a speaker 315 connected to the speaker amplifier 314 are sequentially provided.
In the internal device 32, a microphone 321, a microphone amplifier 322, and an echo canceller 323 are sequentially provided, and a speaker amplifier 324 connected to the echo canceller 323 and a speaker 325 connected to the speaker amplifier 324 are sequentially provided. The speaker amplifier 324 of the internal device 32 is connected to the echo canceller 313 of the external device 31, and the echo canceller 323 of the internal device 32 is connected to the speaker amplifier 314 of the external device 31, respectively.

In such a loudspeaker type communication device, the wall K
3 is input to the microphone 311 of the external device 31 and amplified by the microphone amplifier 312 to become the microphone amplifier output signal S312. The internal speaker amplifier input signal S3 is output from the echo canceller 313.
24 and the echo canceller 313
The external echo feedback electric quantity signal S313 corresponding to the detected sound pressure is output to the speaker amplifier 314. The internal speaker amplifier input signal S324 drives the speaker amplifier 324, and is output from the speaker 325 as an external speaker voice output S325. The external speaker voice output S325 is input to the microphone 321 together with the internal speaker voice S321 as the internal feedback voice S326, amplified by the microphone amplifier 322, input to the echo canceller 323 as the microphone amplifier output signal S322, and drives the speaker amplifier 314. External speaker amplifier input signal S31
4 is output. Here, the difference between the external speaker amplifier input signal S314 and the external echo feedback electric quantity signal S313 from the echo canceller 313 is equal to the speaker amplifier 31.
4 and the external speaker voice S3 from the speaker 315
Only the internal speaker voice from which 11 has been removed is output.

Similarly, the internal speaker voice S321 of the speaker H32 in the room R3 is input to the microphone 321 of the internal device 32, amplified by the microphone amplifier 322 to become a microphone amplifier output signal S322, and output from the echo canceller 323 to the external speaker. The sound pressure is output as the amplifier input signal S314, the sound pressure is detected by the echo canceller 323, and the internal echo feedback electric quantity signal S323 corresponding to the detected sound pressure.
Is output to the speaker amplifier 324. The external speaker amplifier input signal S314 drives the speaker amplifier 314 and is output from the speaker 315 as an internal speaker voice output S315. The internal speaker voice output S315 is input to the microphone 311 together with the external speaker voice S311 as the external feedback voice S316, and is amplified by the microphone amplifier 312 as the microphone amplifier output signal S312.
3, an internal speaker amplifier input signal S324 for driving the speaker amplifier 324 is output. Here, the external speaker amplifier input signal S324 and the external echo feedback electric quantity signal S313 from the echo canceller 323 are output.
Is input to the speaker amplifier 324, and only the external speaker's voice from which the internal speaker's voice S321 has been removed is output from the speaker 325, and a good loudspeaker conversation is performed.

[0007]

However, such a loudspeaker-type communication apparatus requires two sets of speakers and a driving amplifier, and requires a headset or two echo cancellers which burden the user. Was. In addition, since the external speaker cannot confirm how much the sound pressure of the external speaker is in the room, the external speaker tends to speak with an unnecessarily loud voice.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned disadvantages, and does not use a headset that imposes a burden on a user, or eliminates the need for two echo cancellers to prevent the occurrence of howling by a simple configuration, and to reduce external noise. It is an object of the present invention to provide a loudspeaker apparatus capable of confirming to a speaker how much sound pressure the speaker's voice has inside and speaking with an appropriate voice.

[0009]

In order to achieve the above object, a loudspeaker system according to the present invention comprises a planar speaker having a symmetrical directional characteristic disposed on an acoustically isolated window or the like. One microphone is arranged on each of the front and back sides of the surface, and an amplifier for amplifying the sum of the outputs of both microphones and driving the flat speaker is provided.

In this loudspeaker type communication device, a plane speaker having directional characteristics symmetrical to the front and back is provided at an acoustically isolated window, and microphones are installed in the speaker surface direction of the plane speaker, that is, microphones are installed at the front and back of the window. Place the microphone in an area where sound waves radiated from the speaker are small,
Since the sound waves radiated from the planar speakers input to the two microphones are symmetrical, the sound waves radiated from the planar speakers input to the two microphones are added together and are eliminated, thereby completely reducing the occurrence of howling. Can be removed. For this reason, it is not necessary to force the user to wear a headset, and a simple configuration can be achieved without the need for two echo cancellers, a speaker, and an amplifier. Also, since the external speaker emits his / her own voice from the flat speaker, it is possible to confirm how much sound pressure is inside the speaker, and therefore, it is possible to speak with an appropriate volume of voice.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a loudspeaker type communication apparatus according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, the loudspeaker apparatus of the present invention is a loudspeaker apparatus which has a conversation through a window 10 inside and outside a room R1 which is acoustically isolated,
A flat speaker 15 is provided on the wall K1 on which the window 10 is provided.
Are provided, and microphones 11 and 12 are provided on the front and back of the wall K1 on which the planar speaker 15 is provided. Further, microphones 11 and 12 have microphone preamplifiers 11a and 11a, respectively.
2a is connected, and a mixer 13 for mixing the audio signals S11a and S12a respectively output from the microphone preamplifiers 11a and 12a, and an amplifier 14 for amplifying the sum signal from the mixer 13 and outputting the sum signal to the flat speaker 15 are sequentially provided.

As shown in FIGS. 2 (a) and 2 (b), the flat speaker 15 of such a loudspeaker-type communication device has a magnetic housing 15a formed of a front housing 15c and a rear housing 15d. A magnet 15e is provided on the front housing 15c and the rear housing 15d, respectively.
15f, and the planar voice coil 15 formed on the housing flexible board between the magnets 15e and 15f.
b.

The plane speaker 15 has directivity only on the normal line of the speaker surface, and the front area 17 of the plane speaker 15
The sound pressure is high, and the sound wave propagation is small in the direction 18 parallel to the speaker surface except for the front region 17.
Therefore, the direction 18 parallel to the speaker surface of the flat speaker 15
Microphones 11 and 12 are located in an area where the sound wave transmitted from the planar speaker 15 is extremely small.

Further, as shown in FIG.
The sound waves emitted from the front and back of No. 5 are equal in amplitude and opposite in phase.

The operation of the loudspeaker apparatus having such a configuration will be described.

The external speaker voice S of the speaker H11 outside the wall K1
11 is input to the microphone 11 and subjected to acoustoelectric conversion, and then amplified by the microphone preamplifier 11a to obtain the audio signal S1.
1a is input to the mixer 13. On the other hand, room R1
The internal speaker's voice S12 of the speaker H12 is input to the microphone 12 and subjected to acoustoelectric conversion.
Is amplified by the mixer 1 as an audio signal S12a.
3 is input. In the mixer 13, the audio signal S1
2a and the audio signal S11a are added to form a sum signal S13. The sum signal S13 is amplified by the amplifier 14 and output to the flat speaker 15 as the speaker drive signal S14. Audio outputs S151 and S152 having the same amplitude and opposite phases are output from the front and back of the planar speaker 15, respectively.
For this reason, the audio signal S15 of both the external speaker voice S11 input to the microphone 11 and the internal speaker voice S12 input to the microphone 12 is output from the planar speaker 15.
1. Since the sound is emitted in step S152, the external speaker H11 is output.
Can see the loudness of his voice and does not speak unnecessarily loud.

Here, the sound waves of the audio outputs S151 and S152 output from the flat speaker 15 are
Because of the characteristics described above, the sound waves are mainly propagated to the front region 17 and only a small amount of sound waves are propagated in the direction 18 parallel to the speaker surface of the planar speaker 15, so that the microphone 11, which is attached to the wall K1 on the same surface as the planar speaker 15, 12 are small, the feedback signals S153 and S1 are small even if slight feedback voices S153 and S154 are input from the front and back microphones 11 and 12 of the wall K1.
Numeral 54 is equal in amplitude and opposite in phase, and when these are input to the mixer 13 via the microphone preamplifiers 11a and 12a and added, they are completely deleted. As a result, voices without howling in the external speaker H11 and the internal speaker H12 are amplified from the planar speaker 15. When the volume of the room R1 is small, the flat speaker 1
Since the audio signal S152 output from 5 may hit the wall K1a and be reflected and input to the microphone 12 again, howling may occur. Therefore, it is preferable that the reflection portion of the audio output S152 of the wall K1a be the sound absorbing wall 16.

[0018]

As is apparent from the above description, according to the loudspeaker apparatus of the present invention, a flat speaker having symmetrical directional characteristics is provided at an acoustically isolated window, and the speaker surface of the flat speaker is provided. By installing microphones installed in the direction, that is, on the front and back of the window, the microphones are installed in an area where sound waves radiated from the speaker are small, and symmetrical sound waves radiated from the flat speaker are input from two microphones respectively. The summing eliminates the howling completely, so that the user is not forced to wear a headset, and the simple construction eliminates the need for two echo cancellers, speakers and an amplifier. Occurrence can be completely eliminated. Also, since an external speaker can check how much the sound pressure of his / her own voice is inside, he / she can speak with a voice of an appropriate volume.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a loudspeaker type communication apparatus according to the present invention.

FIG. 2 (a) is a cross-sectional view of a flat speaker in a loudspeaker apparatus of the present invention. (B) The top view of the flat speaker in the loudspeaker apparatus of the present invention.

FIG. 3 is a diagram for explaining the operation of the loudspeaker type communication apparatus of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional loudspeaker apparatus.

FIG. 5 is a diagram showing a configuration of a conventional loudspeaker apparatus.

[Explanation of symbols]

 10 Window 11 and 12 Microphone 14 Amplifier 15 Planar speaker K1 Wall (surface of window)

Claims (1)

[Claims] A flat loudspeaker (15) having symmetrical directional characteristics is placed on a surface (K) of an acoustically isolated window (10) or the like.
1), one microphone (11, 12) is arranged on each of the front and back surfaces thereof, and an amplifier (14) for amplifying the sum of the outputs of both microphones and driving the flat speaker is provided. Characteristic loudspeaker.