JPH04108246A - Hand-free telephone set - Google Patents

Abstract

PURPOSE:To avoid the effect of external noise by providing a noise microphone picking up external noise and a filter having an undesired component elimination means eliminating an echo from a transmission signal by a reception signal to a talking speaker at talking to the telephone set. CONSTITUTION:The telephone set is provided with a noise microphone 35 picking up external noise and an adaptive digital filter(ADF) 37 as a filter in common use for a noise canceller function and an echo canceller function. Then in the case of voice dialing, the ADF 37 acts like a noise canceller and eliminates noise inputted from a talking microphone 1 based on the external noise collected by the noise microphone 35. Moreover, the ADF 37 acts like the echo canceller during talking, the echo is eliminated without being effected by the external noise and talking is implemented in a natural and excellent quality voice.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hands-free telephone device that allows telephone calls without using hands.

[Prior Art] Hands-free telephones have been used in the past, such as car phones, which allow drivers to make calls without using their hands in consideration of safety and operability when making calls while driving. The device is known. As this hands-free telephone device, for example, the one described in "Oki Research and Development VOL, 56, No. 1, No. 44" is known. This hands-free telephone device will be briefly explained below using FIG. 2.

In the figure, reference numeral 1 denotes a microphone for telephone calls, which is used by a person 2 who makes a hands-free telephone call (hereinafter referred to as a "near-end speaker") to input his or her voice. 3 is an A/D converter, and this A/D converter 3 converts an analog signal from the telephone microphone 1 into a digital signal and outputs it to the voice recognition circuit 4. This voice recognition circuit 4 recognizes registered words input from the telephone microphone 1 via the A/D converter 3. 5 is a control section, and this control section 5 exchanges commands and responses with the voice recognition circuit 4, and controls the entire system.

6 is a voice response circuit, and this voice response circuit 6 is connected to the control unit 5.
A voice message signal is output to the D/A converter 7 in response to a command from the D/A converter 7, and a voice message is generated from a speaker 10, which will be described later. The voice recognition circuit 4, control section 5, and voice response circuit 6 constitute a voice dialing device.

Reference numeral 8 denotes a radio device which transmits a transmission signal from the near-end speaker 2 inputted from the microphone 1 for communication to the other party via the antenna 9. The above-mentioned speaker 10 mainly includes an antenna 9
, the reception signal from the other party captured via the radio 8 is converted into voice and uttered.

11 is a handset, and this handset 11 is connected to a transmitting signal line 12 and a receiving signal line 13 via handset changeover switches 14 and 15. The handset changeover switch 14.15 connects the handset 11 to the radio 8 side when the handset 11 is lifted up, and connects the telephone microphone 1 and speaker 10 to the radio 8 side when the handset 11 is put down. It is set as follows.

17 is an audio switch control circuit for preventing acoustic echo; this audio switch control circuit 17 is connected to the transmission signal line 1;
It is connected to echo prevention changeover switches 18 and 19 provided on the receiving signal line 13 and the receiving signal line 13, respectively, and controls to close the dominant switch 18, 19 by comparing the sending signal and the receiving signal.

Note that 20 is a changeover switch for switching the connection between the speaker 10 and the voice response circuit 6 side or the radio device 8 side.

When making a hands-free call, the near-end speaker 2 first utters registered words into the call microphone 1. The voice emitted by the near-end speaker 2 is input as an analog signal from the telephone microphone 1, and is converted into a digital signal by the A/D converter 3. This signal is input to the voice recognition circuit 4, recognized by the voice recognition circuit 4, and outputted to the control section 5. The control unit 5 receives the output signal from the voice recognition circuit 4 and outputs the voice recognition signal to the voice response circuit 6, and the voice response circuit 6 that receives the voice recognition signal transmits the voice message signal to the D/A converter 7. , is output to the speaker 10 via the changeover switch 20, and the speaker 10 issues a confirmation voice message to the near-end speaker 2. Then, by repeating the input of registered words and the sending and receiving of voice messages, confirming the call destination and receiving and receiving commands to start calling, etc., a call is made, and a call signal for line connection is sent to the wireless device 8. , is automatically transmitted via antenna 9 and the line is connected,
A hands-free call will begin.

During a call, the voice of the near-end talker 2 is sent as a transmission signal to the call microphone 1, the radio 8, and the antenna 9.
The transmitted voice of the other party reaches the near-end speaker 2 via the antenna 9, the radio 8, and the speaker 10 as a reception signal.

In the case of this hands-free call, the sound emitted from the speaker 10 reaches the near-end talker 2 and also reaches the call microphone 1.
When the sound reaches the microphone 1, it becomes an acoustic echo and returns to the other party, making it difficult to talk.
Furthermore, when the level of this acoustic echo is high, howling occurs and the call quality deteriorates, so the audio switch control circuit 17 closes the switches 18 and 19 that are dominant for the transmitting signal and the receiving signal. Suppress echo or howling.

Further, in the case of an incoming call operation, a call is started in response to the ringing tone.

[Problems to be Solved by the Invention] By the way, while the vehicle is running, external noises such as engine noise and the sound of tires hitting the ground while the vehicle is running are transmitted into the interior of the vehicle. If a voice dial operation is performed while these noises are occurring inside the vehicle, these noises will be input from the speaker 10 along with the voice, causing the voice dial device to misrecognize the call and prevent the correct call operation from being performed. There is a problem that there is.

Further, even if the calling operation is normal, if these noises and acoustic echoes are large, the voice switch control circuit 17 may become activated during a call, resulting in poor call quality.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a hands-free telephone device that is not affected by external noise and has excellent call quality.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a telephone microphone and a telephone speaker for making calls without using hands, and a voice dialing device for making a call by voice. Applies to hands-free telephone devices with

Such a hands-free telephone device includes a noise microphone that is provided separately from a telephone microphone and picks up external noise, and a noise canceller that removes noise from a transmission signal from the telephone microphone using a noise signal from the noise microphone. The device is equipped with a filter that functions as an echo canceller that removes echo from a transmitted signal using a received signal sent to a telephone speaker.

[Operation] With the above configuration, when making a call, external noise is input from the noise microphone, and the filter functions as a noise canceler based on this noise. As a result, even when the external noise is large, the external noise input from the telephone microphone is removed by the filter, and the calling operation is reliably performed without the voice dialing device erroneously recognizing the voice dialing device.

Furthermore, during a call, the filter functions as an echo canceller, making it possible to achieve excellent quality calls without any echo or howling.

[Example 1] An example of the present invention will be described below based on FIG. 1. Note that this embodiment will also be described using a hands-free car telephone device as an example of the hands-free telephone device. The overall configuration of this hands-free car phone device is almost the same as that of the conventional hands-free car phone device described above, so the same members are given the same reference numerals and their explanations will be omitted.

In the hands-free car telephone device of this embodiment, an A/D converter 3 that converts the audio signal from the microphone 1 into a digital signal is provided directly on the transmission signal line 12, and this transmission to the voice recognition circuit 4 is connected directly to the transmission signal line 12. Talk signal &! 12. Furthermore, a D/A converter 7 to which the voice message signal from the voice response circuit 6 is input is provided directly on the reception signal line 13. In addition, in FIG. 1, the control unit 5
The wiring is omitted.

31 is a D/A provided on the radio device 8 side of the transmission signal line 12
This D/A converter 31 converts the digital signal converted by the A/D converter 3 into an analog signal again and outputs it to the radio device 8. 32 is the radio device 8 of the reception signal line 13
This A/D converter 32 is an A/D converter provided on the side.
converts the analog reception signal input via the antenna 9 and radio device 8 into a digital signal.

Reference numeral 35 is a noise microphone that is provided separately from the telephone microphone 1 and picks up external noise such as the sound of an engine while driving and the sound of tires hitting the ground.
is installed at a location away from the telephone microphone 1, particularly at a location where external noise is likely to be collected, for example, outside the vehicle interior. 36 is an A/D converter, and this A/D converter 36 converts the analog audio signal inputted through the noise microphone 35 into a digital signal, and outputs this digital signal to the ADF 37 side, which will be described later.

Reference numeral 37 denotes an adaptive digital filter (hereinafter referred to as "rADF") which functions as a noise canceler and an echo canceller.The transversal type ADF 37 is generally used, and the number of taps is from 10 speakers to 1 microphone for talking. is determined according to the impulse response length of Furthermore, adaptive control of the ADF 37 is performed by a learning identification method or the like so that the root mean square value of the estimated residual is minimized. And ADF
37 is connected to the transmit signal line 12 via an adder 38 (described later), to the receive signal line 13 side or to the noise microphone 35 side via a control mode changeover switch 39 (described later), and to the noise microphone 35 side. When connected, an estimated noise is created based on the noise signal from this microphone 35, which is added by the adder 38, and functions as a noise filter that removes the noise component of the transmission signal input from the microphone l. let

When connected to the reception signal line 13 side, an estimated echo is created based on the branch signal of the reception signal, and the acoustic echo component of the transmission signal input from the microphone 1 is added by an adder 38. It functions as an echo filter that removes the Further, the ADF 37 feeds back the transmission signal from which the noise component or the acoustic echo component has been removed by the adder 38 to efficiently remove the noise component or the acoustic echo component.

Here, the control mode changeover switch 39 is switched to the noise microphone 35 side during the calling operation, and the ADF 3 is switched to the noise microphone 35 side.
7 functions as a noise canceller, and during a call, it switches to the receiver signal line 13 side and causes the ADF 37 to function as an echo canceller.

Further, a changeover switch 20 and a control mode changeover switch 39 for switching between the speaker lO and the voice response circuit 6 or the radio 8 are controlled by the control unit 5, and the changeover switch 20 is controlled by the control unit 5. Switch the control mode changeover switch 39 to the voice response circuit 6 side and the noise microphone 35 side, and when the line is connected by the calling operation, change the changeover switch 20 to the radio 8 side and turn the control mode changeover switch 39 to the noise microphone 35 side. Switch to the receiving signal line 13 side.

Next, the operation of the hands-free car telephone device configured as described above will be explained.

When the handset 11 is placed, the handset changeover switch 14.15 is switched to the microphone l and speaker 10 side, and the changeover switch 20
is switched to the radio device 8 side, and the control mode changeover switch 39 is switched to the noise microphone 35 side, and is in a standby state.

When making a telephone call while the vehicle is running, the near-end speaker 2 first utters registered words into the telephone microphone 1. This registered word is input from the telephone microphone 1. At this time, external noise is also input from the telephone microphone 1. Furthermore, external noise can be detected using the noise microphone 35.
It is also input from And noise microphone 35
The noise signal input from the control mode changeover switch 39
ADF37 that functions as a noise canceller via
is input and calculated to form an estimated noise, and this estimated noise is added to the transmission signal input from the microphone 1 side in an adder 38.

Further, along with feedback control, noise mixed from the telephone microphone 1 side is removed.

The voice signal from which the noise has been removed is operated in the same way as in the past, and the voice confirmation circuit 4, control unit 5, and voice response circuit 6 issue a confirmation voice message to the near-end speaker 2, and the radio device 8 and antenna A calling signal is transmitted via 9.

When the line with the other party is connected, the control unit 5 switches the two switches 20.39 to connect the radio 8 and the speaker 10 side, and also connects the radio 8 and the ADF 37 side. The content of the call is transmitted to the near-end speaker 8 by the speaker 10 in response to the reception signal from the speaker, and a branch signal of the reception signal is input to the ADF 37 which functions as an echo canceller. Then, the echo generated when input from the speaker 10 to the telephone microphone 1 is removed by an estimated echo created based on the branch signal input to the ADF 37.
Prevents acoustic echo and howling.

As described above, in the hands-free car telephone device of the present embodiment, during voice dialing operation, the ADF 37 functions as a noise canceller, and input from the telephone microphone 1 is based on the external noise collected by the noise microphone 35. Since the noise generated by the vehicle is removed, the voice dialing operation can be performed reliably even when the driving noise is large.

Furthermore, during a call, the ADF 37 functions as an echo canceller and removes echoes based on the branch signal of the received signal, so that the call can be made with natural and high-quality voice.

In addition, since only one ADF 37 is provided and serves as both an echo canceler and a noise canceler, the number of parts can be reduced and an inexpensive, high-performance hands-free car telephone device can be provided.

Although the present embodiment has been described using a hands-free car telephone device as an example, the present invention is not limited to this, and the present invention is not limited to this. Further, if the telephone device is used in a place where there is noise surrounding the voice dialing operation, the same functions and effects as described above can be achieved.

[Effects of the Invention] As detailed above, the hands-free telephone device of the present invention provides the following effects.

(1) During voice dialing, the filter functions as a noise canceller and eliminates the noise input from the calling microphone based on the external noise collected by the noise microphone, so even if the driving noise is large, this noise can be removed. To efficiently perform voice dialing without causing a malfunction of a voice dialing device.

(2) During a call, the filter functions as an echo canceller and removes the echo based on the branch signal of the received signal, so that the call can be made with natural and high-quality voice.

(3) Since only one filter is provided and it functions as both an echo canceler and a noise canceler, the number of parts can be reduced, and an inexpensive, high-performance hands-free telephone device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a hands-free car phone device of the present invention, and FIG. 2 is a block diagram showing a conventional hands-free car phone device. 1... Microphone for calling, 4... Voice recognition circuit,
5... Control unit, 6... Voice response circuit, 35... Noise microphone, 36... A/D converter, 37...
...ADF. 1. Display address of the case (105) 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd. Representative Nobumitsu Kosugi 4 Address of agent (4-chome Shibaura, Minato-ku, Tokyo 108) 10 No. 3 No. 5,
``Detailed Description of the Invention'' column and drawings of the specification to be amended. 6. Contents of correction (1) On page 9 of the specification, lines 3 to 4, the A/'D converter 3 that changes the digital signal is changed to ``The A/D converter 3 that converts the digital signal into the digital signal is'' and correct it. (2) “Efficiently” on page 11, line 14 of the specification is F.
6,” he corrected. (3) Amend Figure 1 of the drawing as shown in the attached sheet. that's all

Claims (1)

[Claims] A hands-free telephone device comprising a microphone and a speaker for making calls without using hands, and a voice dialing device for making a call by voice, comprising: A noise microphone is installed separately and picks up external noise. During voice dialing, the noise signal from the noise microphone is used to remove noise components from the transmission signal of the telephone microphone. 1. A hands-free telephone device comprising: a filter having an unnecessary component removing means for removing an echo from a transmitted signal according to a signal.