JP2005247181A - Vehicle-mounted handsfree system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable echo canceling processing during hands-free communication at an automobile phone and a mobile phone and the like to be positively carried out by a simple configuration. <P>SOLUTION: This vehicle-mounted handsfree system has a first microphone 12, a second microphone 13, amplifier circuits 14, 15 for amplifying output levels of these first and second microphones 12, 13 and a differential amplifying circuit 16 for synthesizing output signals outputted from the amplifier circuits 14, 15. A speaker 11 is arranged at a position equally spaced apart in distance from each of the first microphone 12 and the second microphone 13 so as to eliminate travel noise and an echo signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an in-vehicle hands-free device that is used for a hands-free call such as a car phone system and cancels an echo sound generated between a received voice and a transmitted voice during communication and a running noise generated during driving. is there.

  FIG. 5 shows a configuration of an echo canceling device conventionally used in a hands-free device. Hereinafter, it demonstrates according to drawing.

  This hands-free device has a microphone 2 for inputting a driver's voice signal, and an output side thereof is connected to a radio 10 via an A / D converter 3, an echo canceller 7, and a D / A converter 8. Yes. The wireless device 10 is connected to a speaker 1 that outputs a received voice signal via an A / D converter 9, an echo canceller 7, and a D / A converter 4. The echo canceller 7 eliminates an acoustic echo from the speaker 1 to the microphone 2 and includes an adaptive filter (ADF) 6 and an adder 5.

  Next, the operation will be described. During a hands-free call, the driver can listen to the other party's voice transmitted through the wireless device 10 through the A / D converter 9, the echo canceller 7, the D / A converter 4 and the speaker 1 as a received signal. . The voice signal of the speaker is sent to the wireless device 10 via the microphone 2, the A / D converter 3, the echo canceller 7, and the D / A converter 8, and is transmitted to the speaker.

  In the case of this hands-free call, there is a problem that the sound from the speaker 1 echoes in the vehicle and is input to the microphone 2 to become an acoustic echo and return to the far-end speaker again, making it difficult to make a call. In particular, when the level of acoustic echo is high, howling occurs and the speech quality deteriorates. For this reason, the echo canceller 7 eliminates acoustic echoes and suppresses deterioration in call quality. In the echo canceller 7, the speech signal from the far-end speaker output from the A / D converter 9 is input to the adaptive filter (ADF) 6 as a reference signal, and the echo path is transmitted by the adaptive filter (ADF) 6. The characteristics are adaptively estimated and an echo cancellation signal is output to the adder 5. The adder 5 cancels the acoustic echo by subtracting the echo cancellation signal from the signal from the microphone 2.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP-A-6-153289

  However, the conventional echo cancellation apparatus requires the adaptive filter (ADF 6) for performing echo cancellation processing, the A / D conversion circuit 3, and the D / A conversion circuit 4, and the signal processing scale and apparatus scale increase. There was a drawback.

  The present invention solves such a problem in the conventional technology, and can cancel echo during hands-free calling such as an in-vehicle hands-free device, and also realizes cost reduction of the device by reducing the echo cancel circuit. be able to.

  In order to achieve the above object, the invention described in claim 1 of the present invention, in particular, is a speaker for outputting a received voice signal and a first for collecting a transmitted voice signal as a desired input signal. , A second microphone, an amplifier circuit for amplifying the output levels of the first and second microphones, and a differential amplifier circuit for synthesizing an output signal output from the amplifier circuit, An in-vehicle hands-free device that removes running noise and echo signals by disposing the speakers at positions equal to each other from the microphone and the second microphone, whereby the differential amplifier circuit is connected via the microphone. It is possible to remove the running noise and echo voice signal input in this way, and to obtain the desired voice input voice signal with high accuracy. .

  The invention according to claim 2 of the present invention is characterized in that, in particular, the first and second microphones and the speaker are arranged at a position where the voice of the caller is sufficiently collected in the front of the vehicle interior, As a result, when the noise source is generated in front of the passenger compartment, the noise component can be reliably reduced or removed, and the acoustic echo component output from the front speaker can also be reduced or eliminated. On the other hand, when the caller is seated in the front of the passenger compartment, the transmission voice signal is easily collected.

  The invention described in claim 3 of the present invention is characterized in that, in particular, the first and second microphones and the speaker are arranged at positions where the voice of the caller is sufficiently collected in the rear of the vehicle interior. Thus, when the noise source is generated behind the vehicle interior, the noise component can be reliably reduced or removed, and the acoustic echo component output from the rear speaker can be reduced or eliminated. On the other hand, when the caller is seated in the back of the passenger compartment, the transmission voice signal is easily collected.

  In the invention according to claim 4 of the present invention, in particular, the speaker and the first and second microphones are arranged in both the front and the rear of the vehicle interior, and the speaker and the microphone to be used can be switched between the front and the rear. As a result, it is possible to obtain an effect that the caller can talk regardless of the boarding position.

  The invention described in claim 5 of the present invention is characterized in that, in particular, a microphone used in a system other than the hands-free system is used as the first and second microphones for hands-free use. The effect of reducing the overall cost and reducing the number of wires can be obtained.

  The invention described in claim 6 of the present invention is characterized in that, in particular, a speaker used in a system other than a hands-free system is used as a speaker for a hands-free application, thereby reducing the cost of the entire system and wiring. The effect that the number can be reduced is obtained.

  The in-vehicle hands-free device of the present invention collects a speaker for outputting a received voice signal, a transmission voice signal as a desired input signal, a running noise as a disturbance input signal, and an echo voice signal from the speaker. The first and second microphones, an amplifier circuit for amplifying the output levels of the first and second microphones, and a differential amplifier circuit for synthesizing the output signals output from the amplifier circuit, The speaker is arranged at a position that is equal to each other from each of the first microphone and the second microphone, and the acoustic echo from the speaker can be obtained with a simple configuration without using a complicated configuration such as an acoustic echo canceller circuit. Noise sources generated during operation can be canceled sufficiently.

(Embodiment 1)
Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of an in-vehicle hands-free device according to Embodiment 1 of the present invention, in which a first microphone 12 and a second microphone 13 are arranged at equal distances from a speaker 11 to collect sound. In order to amplify the signal, the first microphone 12 is connected to the first amplifier circuit 14, and the second microphone 13 is connected to the second amplifier circuit 15. Further, the first and second amplifier circuits 14 and 15 are configured to be connected to a differential amplifier circuit 16 which is a combining means for combining the amplified outputs.

  Next, the operation will be described. First, the reception voice signal from the far-end speaker is output from the speaker 11, and the first and second acoustic echoes from the speaker 11, running noise generated during driving, and the transmission voice signal from the near-end speaker are first and second. Sound is collected by the microphones 12 and 13. The collected signals are amplified by the first and second amplifier circuits 14 and 15, and the differential value between the amplified first and second signals 17 and 18 is calculated by the differential amplifier circuit 16. Output.

  In the present invention, since the distances from the speaker 11 to the first microphone 12 and the second microphone 13 are equal, the received voice signal of the far-end speaker is in phase and phase even if it is output to the vehicle interior as an acoustic echo by the speaker 11. Sound is collected at the level. Further, since the differential amplifier circuit 16 calculates and outputs the difference value between the signals 17 and 18, the acoustic echo component from the speaker 11 is canceled and reduced or eliminated. Further, engine noise generated during driving, and traveling noise such as road noise are similarly canceled and reduced or eliminated.

  On the other hand, the transmitted voice signal of the near-end speaker is collected by the first microphone 12 and the second microphone 13, but usually between the speaking position and the first microphone 12 and the second microphone 13. Therefore, transmitted voice signals having different amplitudes and phases arrive at the microphone 12 and the microphone 13. Therefore, even if the near-end speaker's transmitted voice signal input to the microphones 12 and 13 is input to the differential amplifier circuit 16 and the difference value is calculated, the amount of attenuation is smaller than that of the far-end speaker's acoustic echo. The output of the differential amplifier circuit 16 can be used as a transmission signal for the near-end speaker with very little.

  Next, the actual acoustic echo attenuation effect according to the configuration of the first embodiment will be described with reference to FIG. In FIG. 2, the speaker 11 is disposed on the front center panel 20 of the vehicle interior 22, and the first microphone 12 and the second microphone 13 are the front ceiling portions directly above the driver seat and the passenger seat, which are equidistant from the speaker 11. 24.

  Here, a signal source 21 to be a pseudo echo signal is connected to the speaker 11, and the oscillation frequency of the signal source 21 is continuously swept from 20 Hz to 20000 Hz. Then, output is performed by the speaker 11, and sound output from the speaker 11 is collected by the first microphone 12 and the second microphone 13.

  Further, the transmission frequency and phase characteristics of the output signals 17 and 18 obtained by amplifying the signals collected by the first microphone 12 and the second microphone 13 by the amplifier circuits 14 and 15 are compared. As a result, in the frequency range up to 3000 Hz, it was confirmed that substantially the same characteristics were obtained for the output levels and phase characteristics of the output signals 17 and 18 obtained by amplifying the signals from the microphone inputs.

  Next, the transmission frequency characteristic of the acoustic echo reduction effect in Embodiment 1 of the present invention will be described using FIG. In FIG. 3, the transmission frequency characteristics of the output signals 17 and 18 obtained by amplifying the signals from the microphone inputs are indicated by broken lines, and in order to confirm the attenuation effect of the acoustic echo according to the configuration of the present invention, The transmission frequency characteristics of the differential output signal 19 when the output signals 17 and 18 are input to the differential amplifier circuit 16 are indicated by solid lines.

  In FIG. 3, the frequency region applied in the present invention is 20 to 3400 Hz that is a frequency region in a telephone line, so the output signals 17 and 18 in the frequency region and the transmission frequency of the differential output signal 19 are compared. Then, the attenuation amount of the acoustic echo can be secured up to 25 dB by adopting the configuration of the present invention, and the effect that the acoustic echo can be reduced is obtained.

  With the above configuration, it is possible to reduce the running noise and echo sound signal input through the first and second microphones 12 and 13, and to output the transmitted sound signal as the desired input signal with high accuracy. it can.

  In the first embodiment, as shown in the configuration diagram of the automobile using the in-vehicle hands-free device in FIG. 4, since the voice of the caller in front of the passenger compartment 22 is sufficiently collected, the speaker 11 Are arranged on the front center panel 20 of the vehicle interior 22 and the first and second microphones 12 and 13 are arranged on the front ceiling portion 24. However, the speaker 11 is connected to the front ceiling portion 24 of the vehicle interior 22 and the front overhead console portion 26. The first and second microphones 12 and 13 are placed at any of the positions of the front seat portion 23 of the driver seat and the passenger seat, the front headrest portion 25, the front overhead console portion 26, the front door portion 27, and the front seat belt portion. You may arrange | position in either.

  In addition, the speaker 11 is placed at any one of the rear tray part 34 and the rear ceiling part 30 located in the rear center of the car interior so that the voice of the caller in the car interior 22 is sufficiently collected. The second microphones 12 and 13 may be arranged at any position of the rear rear seat portion 29, the rear ceiling portion 30, the rear headrest portion 31, the rear door portion 32, and the rear seat belt portion 33.

  It is also possible to arrange the speaker 11 and the first and second microphones 12 and 13 in front and rear of the vehicle interior 22 so that the front and rear can be switched depending on the situation.

  Furthermore, a microphone used in a non-hands-free device such as a voice recognition device for navigation and a sound reproducing device for correcting ambient noise masking, and a speaker used in a device other than a hands-free device such as a sound reproducing device, respectively. It can also be used as a hands-free application.

  The in-vehicle hands-free device according to the present invention can sufficiently cancel the acoustic echo from the speaker and the noise source generated during operation with a simple configuration without using a complicated configuration such as an acoustic echo canceller circuit, This has the effect that the caller can talk regardless of the boarding position in the passenger compartment, and is useful as a hands-free system such as a car phone.

Configuration diagram of in-vehicle hands-free device in Embodiment 1 of the present invention Configuration diagram of in-vehicle hands-free device in the embodiment Transmission frequency characteristic diagram of acoustic echo reduction effect in the same embodiment Configuration diagram of an automobile using the in-vehicle hands-free device in the embodiment Configuration diagram of conventional in-vehicle hands-free device

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Speaker 12 1st microphone 13 2nd microphone 14 1st amplifier circuit 15 2nd amplifier circuit 16 Differential amplifier circuit 17 1st signal 18 2nd signal 19 Differential output signal 20 Center panel 21 Signal source 22 Car interior 23 Front seat part 24 Front ceiling part 25 Front headrest part 26 Overhead console part 27 Front door part 28 Front seat belt part 29 Rear seat part 30 Rear ceiling part 31 Rear headrest part 32 Rear door part 33 Rear seat belt part 34 Rear tray part

Claims (6)

A speaker for outputting a received voice signal, first and second microphones for collecting a transmitted voice signal as a desired input signal, and amplification for amplifying the output levels of the first and second microphones A speaker and a differential amplifier circuit that synthesizes an output signal output from the amplifier circuit, and the speaker is disposed at a position that is equal to each other from the first microphone and the second microphone. An in-vehicle hands-free device that removes running noise and echo signals. The first and second microphones are connected to the front seat portion of the driver's seat and front passenger seat where the voice of the caller in front of the vehicle interior is sufficiently collected, the front ceiling portion of the front seat, the front headrest portion, the overhead console portion, The speaker is disposed at any position of the front door portion and the front seat belt portion, and the speaker is disposed at any one of the center panel portion, the overhead console portion, and the front ceiling portion located in the front center of the vehicle interior. The in-vehicle hands-free device according to Item 1. Position of the first and second microphones at any one of a rear seat part, a rear ceiling part of the rear seat, a headrest part, a rear door part, and a rear seat belt part where the voice of the caller is sufficiently collected in the rear of the vehicle interior The hands-free device according to claim 1, wherein the speaker is disposed at any one of a rear tray part and a rear ceiling part located in the rear center of the automobile interior. The hands-free device according to claim 1, wherein the speaker and the first and second microphones are respectively arranged in front and rear of the vehicle interior so that switching between the front and rear speakers and the microphone is possible. The in-vehicle hands-free device according to claim 1, wherein a microphone used in a system other than the hands-free system is used as the first and second microphones for hands-free use. The in-vehicle hands-free device according to claim 1, wherein a speaker used in a system other than the hands-free system is used as a speaker for hands-free use.

Images