JPH1188980A - Terminal voice noise reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise received by a built-in microphone with high accuracy at a low cost with a simple configuration. SOLUTION: A voice uttered from the operator at a side of a front panel 32a of a terminal equipment is picked up by a microphone 42 provided to the front panel 32a and sneaked to the rear side of the front panel 32a and picked up by a microphone 43 provided in a case. Noise sound such as wind break sound of a cooling fan in the terminal equipment is picked up by the microphone 43 and sneaked to the front panel 32a and picked up by the microphone 42. A voice signal extract circuit 50 mixes output signals of the two microphones 42, 43 to cancel the noise component and extracts only the voice uttered by the operator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal voice noise reduction device for a network terminal such as a personal computer.

[0002]

2. Description of the Related Art In various terminal devices such as a network terminal device typified by a personal computer, etc., applications using voice (for example, electronic conference,
Voice mail, etc.) has become widespread. Internet telephones and the like using the Internet have also been put into practical use and are being used instead of conventional telephones. Therefore, if you talk naturally to a terminal device such as a small personal computer while looking at the other person's face,
Instead of an external microphone (hereinafter simply referred to as a "microphone"), the microphone itself is built into the terminal device so that it can be conveyed to the other party and that the user can talk with his hands while operating the keyboard and mouse. In order to talk while watching the other party on the display (display unit) of the terminal device, the microphone part is further embedded near the display,
There is a small hole for microphone input. When talking to the display, audio is input through a small hole. In this type of terminal device, for example, when the device is a personal computer class or the like and high-speed processing is required, a cooling fan is used inside, and the noise is circulated into the microphone,
Sufficient audio signal-to-noise (hereinafter "S / N")
In many cases, various terminal voice noise reduction devices have been proposed to prevent such problems.

FIG. 2 is a schematic diagram showing an example of a conventional terminal noise reduction device. FIG. 2 shows a cross section of a microphone attachment portion of the terminal device. The terminal device 10 includes a housing 1 molded from plastic or the like.
1, a small hole 12 for inputting sound A is formed in a front panel located on the operator side of the housing 11. A microphone 13 is embedded inside the hole 12, and the microphone 13 is connected to an audio circuit of an electronic device in the terminal device 10 via a cable 14. Further, a fan 20 for cooling the electronic device is provided in the housing 11. When the fan 20 rotates, the wind noise is reflected intricately inside the housing and reverberated, resulting in noise B
Since the input is made from the back side of the microphone 13, the back side of the microphone 13 is covered with a sound absorbing material 15 for soundproofing such as rubber to prevent this. In this type of terminal device 10, when an operator generates sound A from the front panel side of the housing 11, the sound A is input to the microphone 13 through the sound input hole 12 and is converted into an audio signal by the microphone 13. Are input to the audio circuit in the terminal device 10 via the cable 14.

For example, in the case of a terminal device 10 such as a personal computer or an integrated terminal employing a cathode ray tube (hereinafter referred to as "CRT") type display,
The periphery is a large space, and the wind noise of the fan 20 for cooling the built-in control board and the central processing unit (CPU) reverberates in the space around the CRT, and noise B with complicated reverberation is generated. This noise B generated in the housing 11
Is fed into the microphone 13 together with the voice A of the operator. Therefore, the noise B significantly deteriorates the voice A of the operator, and the voice which is hard to hear is
This is sent to the other party connected to the terminal device 10. On the other side, even if the content of the voice can be heard, the voice becomes unpleasant sound that is not suitable for enjoying an electronic conference or a conversation. If an external microphone is used, the problem of noise B due to the wind noise of the fan 20 can be avoided, but in this case, problems such as unnecessarily picking up surrounding sounds and requiring an installation space for the external microphone are required. Occurs. Therefore, in the conventional terminal noise reduction device, a hole 12 for voice input is formed in the front panel of the housing 11 as standard, and a microphone 13 is attached from the back side of the hole 12, and the entire back surface of the microphone 13 is Is covered with a sound absorbing material 15 such as rubber to prevent the noise B from entering the microphone 13.

[0005]

However, the conventional terminal noise reduction device of FIG. 2 has the following problems. In order to prevent the noise B from entering the microphone 13, the back side of the microphone 13 is covered with a sound absorbing material 15 having a simple structure. Therefore, the soundproof effect is small, and it is not possible to obtain a sufficient sound quality. In particular, although the voice used in Internet telephones and the like has been improved with the progress of audio data compression technology, high-quality voice can be exchanged at the same level as an optical compact disc (CD) player. There is a problem that the performance cannot be fully utilized due to the noise B that is picked up. In order to solve these problems, the microphone 13 is completely embedded in the mode part of the front panel of the housing 11, and the audio A is input only through the hole 12 formed in the front panel. I have. In this case, the noise B generated inside the housing 11 cannot be directly picked up, but the replacement of the microphone 13 becomes impossible, and the manufacturing process for embedding in the mode part becomes complicated and the cost increases. Occurs. Therefore, it has been difficult to provide a terminal audio noise reduction device that is technically sufficiently satisfactory. The present invention solves the problems of the prior art, and in various terminal devices using a microphone built in a terminal such as a personal computer, the noise input to the microphone has a simple structure and low cost. Therefore, an object of the present invention is to provide a terminal voice noise reduction device capable of reducing the noise with high accuracy.

[0006]

Means for Solving the Problems In order to solve the above problems, a first invention of the present invention relates to a terminal voice noise reduction device, comprising: a housing having a front panel located on the operator side; A terminal device in which electronic equipment capable of voice input is accommodated, and a terminal device attached to the front panel facing the operator side, and a voice generated from the operator side and a voice generated from inside the housing and turned into the operator side. A first microphone that converts the noise into a first audio signal, and a first microphone that is attached to the housing toward the inside of the housing. The noise generated in the housing and the noise emitted from the operator side are inserted into the housing. A second microphone that converts the wraparound sound into a second sound signal, and a second microphone that reverses the phase of the second sound signal with respect to the first sound signal. Wrap noise component An audio signal extraction circuit that cancels out the noise component in the audio signal of No. 2 and extracts only the audio component and the bypass audio component in the first and second audio signals and inputs the extracted audio component and the loop-in audio component to the electronic device. Have. The second invention is
In the terminal audio noise reduction device according to the first invention, the first microphone is exposed to the outside of the housing on a surface of a removable substrate that covers an audio input opening provided in a part of the front panel. And the second microphone is mounted on the back surface of the substrate so as to be exposed inside the housing.

By adopting such a configuration, when noise is generated from a cooling fan or the like in the housing of the terminal device, this noise is directly input to the second microphone and is transmitted to the operator outside the housing. It turns around and is input to the first microphone. The voice generated by the operator is directly input to the first microphone and is also sneak into the housing and input to the second microphone. The first microphone converts the input voice and the loop noise into a first voice signal and sends it to a voice signal extraction circuit. Further, the second microphone converts the input noise and the bypass sound into a second sound signal and sends it to the sound signal extraction circuit. The audio signal extraction circuit cancels the repetitive noise component in the first audio signal and the noise component in the second audio signal, and outputs the audio component and the reentrant audio in the first and second audio signals. Only the components are extracted and input to the electronic device in the terminal device. Thus, high-quality audio can be extracted by the audio signal extraction circuit without the complicated noise generated from inside the terminal device being picked up by the electronic device.

[0008]

FIG. 3 is a perspective view showing the appearance of a terminal device according to an embodiment of the present invention. This terminal device 30
A keyboard 31 for data input is provided, and the keyboard 31 is connected to an electronic device in the housing 32 via a cable. The housing 32 is formed, for example, by molding with plastic or the like, and a display 33 for displaying images is provided on a front panel 32 a of the housing 32. An opening (for example, a small hole) 34 for audio input is formed in a front panel portion above the display 33, and a microphone unit is embedded and mounted on the back side of the hole 34. FIG. 4 is a schematic cross-sectional view of the microphone unit portion of FIG. The microphone unit 40 is embedded and mounted on the back side of the hole 34 formed in the front panel 32a. In the internal space 32b of the housing 32, electronic devices having an audio circuit are accommodated, and a fan 60 for cooling these electronic devices is provided.
The sound A emitted from the operator and the noise B reflected by the wind noise generated by the fan 60 reflected in the internal space 32b in a complicated manner are input to the microphone unit 40.

FIG. 1 is a schematic configuration diagram of a terminal voice noise reduction apparatus according to an embodiment of the present invention. In this FIG.
An enlarged view of the microphone unit 40 part of FIG. 4 is shown. The microphone unit 40 embedded and mounted on the back side of the hole 34 of the front panel 32a has a removable board (for example, a printed board) 41 for closing the hole 34 for voice input. In addition, a first microphone (for example, an inexpensive and small condenser microphone) 42 exposed from the hole 34 is mounted, and a second microphone (for example, an inexpensive , A small condenser microphone) 43 is mounted. Further, an audio signal extraction circuit 50 connected to the condenser microphones 42 and 43 is mounted on the back surface of the printed circuit board 41, and the audio signal extraction circuit 50 is connected to an input side of an audio circuit in the electronic device via a cable 58. It is connected. The condenser microphone 42 attached to the surface of the printed circuit board 41 inputs voice A and the like from the operator side,
Further, the condenser microphone 43 on the back side of the printed circuit board 41 inputs noise B and the like in the internal space 32b. The audio signal extraction circuit 50 has a function of extracting an audio component from the output signals of the condenser microphones 42 and 43 and providing the audio component to the audio circuit via the cable 58.

FIG. 5 is a schematic circuit diagram showing a configuration example of the audio signal extraction circuit 50 of FIG. The two condenser microphones 42 and 43 each have a field effect transistor (hereinafter, referred to as a field effect transistor).
42a and 43a, respectively. The drain of the FET 42a is connected to the power supply potential VCC via the drain resistor 51, and the source of the FET 42a is connected to ground (hereinafter, referred to as "GND"). The drain of the FET 43a is connected to the power supply potential VCC, and the source thereof is connected to the GN via the source resistor 52.
D. The drain of the FET 42a is connected to a node N via a mixing resistor 53, and this node N is connected to the source of the FET 43a via a mixing resistor 54. The resistance value of the mixing resistor 54 is set to be larger than the resistance value of the mixing resistor 53 so as to effectively cancel noise components. Node N
Are connected to the base of an amplifying bipolar transistor 56 via a base resistor 55. Transistor 5
6 is connected to the power supply potential V via the collector resistor 57.
It is connected to the DCC and to the cable 58 via the output terminal OUT. The emitter of the transistor 56 is connected to GND.

Next, the operation of the terminal audio noise reduction device configured as described above will be described. Keyboard 31 of FIG.
Is generated toward the front panel 32a, the voice A is transmitted to the voice input hole 34.
, And the sound A is routed to the back side of the front panel 32 a, and the circulated sound is input to the condenser microphone 43. At this time,
A fan 60 in the housing 32 rotates to cool the internal electronic device. The wind noise of the fan 60 is reflected and reflected in the internal space 32b in a complicated manner, and this noise B is input to the condenser microphone 43, and at the same time, vibrates the housing 32 or leaks out from the gap to the outside so that the front panel 32
a, and the noise is also input to the condenser microphone 42. In the audio signal extraction circuit 50 shown in FIG. 5, the condenser microphone 42 directed to the front side of the front panel 32a outputs the audio A emitted from the operator,
Noise B generated in the internal space 32b is
Is converted into a first audio signal. Further, the condenser microphone 43 directed to the internal space 32b side outputs the noise B generated in the internal space 32b and the sound A generated by the operator on the front panel 3.
The second audio signal is converted into the second audio signal. Of the FETs 42a and 43a constituting these condenser microphones 42 and 43, the F
A first audio signal is output from the drain of the ET 42a, and a second audio signal is output from the source of the FET 43a.

The first audio signal and the second audio signal have opposite phases, are mixed by the mixing resistors 53 and 54, and appear on the node N. At this node N, the noise component in the first audio signal and the noise component in the second audio signal cancel each other, and the audio component and the noise component in the first and second audio signals cancel each other. Only audio components are extracted and appear. The extracted voice component and the bypass voice component are converted into a base signal by a transistor 56 through a base resistor 55.
, The transistor 56 amplifies only the operator's voice signal and outputs it from the output terminal OUT. The audio signal output from the output terminal OUT is sent to an audio circuit in the electronic device via the cable 58, and is transmitted to the other device connected to the terminal device 30. As described above, in the present embodiment, the following (a) to
There is an effect as shown in FIG.

(A) Since the noise B due to the wind noise of the fan 60 in the terminal device 30 can be significantly reduced, low-priced, high-quality sound extraction and provision of the sound can be performed. (B) Since it is not necessary to use an external microphone, the installation space of the device is small, and the terminal device 30 having good usability can be provided. (C) Since the noise B generated on the side of the terminal device 30 is small, the present invention can be applied to, for example, a high-quality voice communication system with an increased compression ratio in voice communication such as the Internet. (D) Since the micro unit 40 can be built in the terminal device 30 with a simple structure, the device can be realized at low cost. (E) The microphones 42 and 43 to be used do not require any special one, and sufficient quality can be obtained even with an inexpensive and small condenser microphone, so that the terminal device 30 can be provided at a low price. (F) Case 32 molded with plastic or the like
Since there is no need to incorporate special parts, the manufacturing process is simplified, and a low-cost molded casing 32 can be used. (G) Since the S / N of the voice is improved, not only the voice but also the voice including BGM etc. in the background can be transmitted with high quality, so that it is possible to cope with a wide range of applications.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications (i) and (ii). (I) The microphones 42 and 43 may use microphones other than the condenser microphone. Also, this microphone 4
The mounting positions 2 and 43 may have mounting positions or mounting structures other than those shown in FIGS. (Ii) The audio signal extraction circuit 50 in FIG. 5 may have a circuit configuration using other transistors or the like. Further, the audio signal extraction circuit 50 may not be provided on the back side of the printed circuit board 41 but may be provided on the audio circuit side in the electronic device. By doing so, the microunit 40 can be made more compact, and the mounting structure on the housing 32 becomes simpler.

[0015]

As described in detail above, according to the first and second inventions, the first and second microphones and the audio signal extraction circuit are provided, so that the following effects are obtained. (A) Since the noise due to the wind noise of the fan in the terminal device can be significantly reduced by the audio signal extraction circuit, low-cost, high-quality audio extraction and its provision can be performed. (B) Since there is no need to use an external microphone, the installation space of the device is reduced, and a terminal device that is easy to use can be provided. (C) Since the noise generated inside the terminal device is small, the present invention can be applied to a high-quality voice communication system with an increased compression ratio in voice communication such as the Internet. (D) Since the first and second microphones can be built in the device with a simple structure, the device can be realized at low cost. (E) As the first and second microphones to be used, no special one is required, and sufficient quality can be obtained even with an inexpensive and small condenser microphone, so that the apparatus can be provided at a low price. (F) Since there is no need to incorporate special components into the housing of the terminal device, the manufacturing process is simplified, and a low-cost housing can be used. (G) Since the S / N of the sound is improved, not only the sound but also the sound including BGM in the background can be transmitted with high quality, so that it is possible to cope with a wide range of applications.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a terminal audio noise reduction device showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional terminal voice noise reduction device.

FIG. 3 is a perspective view of an external appearance of a terminal device according to the embodiment of the present invention.

FIG. 4 is a transverse sectional view showing a microphone unit part of FIG. 3;

FIG. 5 is a schematic circuit diagram showing the audio signal extraction circuit of FIG. 1;

[Explanation of symbols]

 Reference Signs List 30 terminal device 32 housing 32a front panel 34 sound input hole 40 microphone unit 41 printed circuit board 42, 43 capacitor microphone 42a, 43a FET 50 sound signal extraction circuit 53, 54 mixing resistor 55 base resistor 56 transistor 60 fan A sound B noise

Claims (2)

[Claims] 1. A terminal device in which an electronic device capable of voice input is accommodated in a housing having a front panel located on an operator side, wherein the terminal device is mounted on the front panel facing the operator side, A first microphone for converting a sound emitted from the loudspeaker and a turn-around noise generated from the inside of the housing to the operator side and converted into a first audio signal; and a first microphone attached to the housing toward the inside of the housing. A second microphone that converts a noise generated in the housing and a turn-around sound emitted from the operator side and turned into the housing into a second audio signal; The second audio signal is inverted in phase to cancel the loop noise component in the first audio signal and the noise component in the second audio signal to cancel the first and second audio signals. Speech components and wraparound An audio signal extraction circuit for extracting only an audio component and inputting the extracted audio component to the electronic device. 2. The terminal audio noise reduction device according to claim 1, wherein said terminal is exposed to the outside of said housing on a surface of a removable substrate which closes a voice input opening provided in a part of said front panel. Attach the first microphone, and on the back of the substrate,
A terminal audio noise reduction device, wherein the second microphone is mounted so as to be exposed inside the housing.