JPH0518149U - Hand-free phone for car phone - Google Patents

Abstract

(57) [Abstract] [Purpose] In a hands-free telephone for car phones used in automobiles equipped with audio equipment such as radio and car stereo, input to the microphone of the hands-free telephone without turning off the power of the audio equipment. The audio signal component from the audio device to be removed is removed. A voice signal component from the audio device 10 that is input to a microphone of a hands-free telephone, using the audio signal of the audio device 10 as a reference signal of the adaptive filter 30, is provided in the preceding stage of a circuit that prevents the other speaker signal Sr from wrapping around. The audio signal erasing circuit 20 for removing the signal is provided to prevent the other party's speaker signal Sr from wrapping around and prevent the audio signal from being mixed into the transmission signal.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hand-free telephone for a car phone used in a car equipped with an audio device such as a radio or car stereo, and removes an audio signal from the audio device input to the microphone of the hand-free phone. It is a thing.

[0002]

[Prior Art]

 As a method of reducing the volume of an audio device in a hands-free telephone for a car phone equipped with an audio device, there are methods described in Japanese Utility Model Publication No. 62-51847 and Japanese Utility Model Publication No. 62-68376. In Japanese Utility Model Laid-Open No. 62-51847, a control circuit for reducing the volume of the audio device according to the outgoing and incoming calls of the telephone is provided, so that the volume of the audio device is automatically reduced during the call of the hands-free telephone. Therefore, it is not necessary to manually operate the volume switch for each call. Further, Japanese Utility Model Laid-Open No. 62-68346 discloses a hand-free telephone for an automobile equipped with an audio device, which includes a power switch for turning on / off the power of the audio device regardless of the operation control mode selected by the changeover switch. It has been proposed that the audio control device be equipped with an operation control circuit, and that the audio device can be turned on and off during a telephone call of a hands-free telephone.

[0003]

[Problems to be solved by the device]

 However, in the method of reducing the volume of the audio device by the control circuit described above, even if the volume of the audio device is reduced when using the hands-free telephone in the vehicle, the sound from the audio device enters the microphone of the hands-free telephone, and The other party's speaker becomes very hard to hear because it is transmitted to the other party's speaker along with the speaker's voice. Also, when the power of the audio device is turned on / off during a call on a hands-free telephone, the other party's talker can hear the other party's ear easily because the other party's talker hears no sound from the other party's talker. If a passenger other than the passenger is listening to the voice or music from the audio device, the voice or music may be temporarily interrupted, which may cause discomfort to the passenger, or may be listening to road information. You may miss it. Therefore, an object of the present invention is to remove a voice signal component from the audio device input to the microphone of the hands-free telephone without turning off the power of the audio device.

[0004]

[Means for Solving the Problems]

 The present invention comprises an audio signal erasing circuit 20 which is activated by a hands-free operation signal provided from a control unit of a telephone, and is connected between a control unit and an audio signal erasing circuit. The hand-free operation signal is set to the operating state, and the other-speaker anti-wraparound circuit 50 for preventing the other-speaker voice from turning around is provided. This audio signal erasing circuit uses an addition means 31 for outputting a difference signal between the output of the hands-free microphone and the output of the adaptive filter, and a difference signal of the addition means for using the audio signal from the audio device as a reference signal. And the adaptive filter whose coefficient is updated according to the signal output.

[0005]

[Action]

 In a hands-free telephone for a car phone used in a car equipped with an audio device such as a radio or car stereo, the audio signal of the audio device is used as a reference signal of the adaptive filter in the preceding stage of the circuit that prevents the other party's signal from wrapping around. An audio signal erasing circuit that removes the voice signal component from the audio device that is input to the microphone of the hand-free telephone is provided, so that the sneak of the other party's signal is prevented and the audio signal is not mixed into the transmission signal. Can be prevented.

[0006]

【Example】

 FIG. 1 is a block diagram showing an embodiment of a hands-free telephone for an automobile telephone according to the present invention. Referring to FIG. 1, when the hands-free telephone main body 100 for a car telephone is not connected to a call, an audio signal Sa from an audio device 10 such as a radio or car stereo is connected to an audio speaker 12 and output. Only. In the start operation of the hands-free telephone main body 100, after the control unit Cu confirms the call connection from the wireless device 40, the hand-free operation signal Cs from the control unit Cu is turned on, the audio signal erasing circuit 20 is operated, and the switch SW1 Is turned on and the audio signal Sa from the audio device 10 is used as the reference audio signal Sas of the adaptive filter 30. The adaptive filter 30 also starts operation. The audio signal Sa is input to a hands-free microphone (hereinafter referred to as a microphone) 13 under the influence of the propagation path and becomes a reception audio signal Sai. The speaker voice Sm is also input to the microphone 13.

The partner speaker signal Sr is output from the partner speaker signal sneak-in prevention circuit (echo canceller or voice switch) 30 and is output from the handsfree telephone speaker 14. The other party's speaker signal Sr is input to the microphone 13 under the influence of the propagation path. The received audio signal Sai, the speaker voice Sm, and the wraparound partner speaker signal Sri input to the microphone 13 serve as an adder input signal of the adder 31. The pseudo audio signal San from the adaptive filter 30 becomes the differential input signal of the adder 31, and the pseudo audio signal San from the audio signal Sai, the speaker voice Sm, and the wraparound partner speaker signal Sri input to the adder 31. The result of subtracting is output from the adder 31 as a speaker signal Smo. The speaker signal Smo is sent to the wireless device 40 through the partner speaker signal wraparound prevention circuit 30 of the hands-free telephone 100.

The speaker signal Smo is input to the adaptive filter 30 as an estimated error signal Smoe of the adaptive filter 30. The adaptive filter 30 uses the reference audio signal Sas as the reference signal and the speaker signal Smo as the estimated error signal Smoe, and updates the coefficient of the adaptive filter 30 so that the estimated error signal Smoe becomes smaller. To end the operation of the hands-free telephone 100, the control unit Cu confirms the call disconnection call disconnection by the control signal Cd from the radio 40 or the handset, etc., and then the control unit Cu turns off the hands-free operation signal Cs and outputs the audio signal. This is done by disconnecting the switch SW1 of the erasing circuit 20 from the adaptive filter 30 and stopping the operation of the adaptive filter 30.

FIG. 2 is a block diagram showing another embodiment of the hands-free telephone for a car telephone according to the present invention. In this configuration, the other-speaker signal Sr output from the other-speaker signal wraparound prevention circuit 30 is output from the audio speaker 12 through the adder 32 without being output from the hands-free telephone speaker 14. Is.

[0010]

[Effect of the device]

 As described above, by using the hands-free telephone for a car telephone of the present invention, it is possible to provide a hands-free telephone for removing the audio signal from the audio device input to the microphone for hands-free telephone. The S / N ratio for the other speaker can be improved, and when passengers other than the speaker in the car are listening to voice or music from the audio device, voice, music, road information, etc. are temporarily interrupted. You can listen without any problems.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

 10 audio device 13 hands-free microphone 20 audio signal erasing circuit 30 adaptive filter 31 adder 32 adder 40 radio device 50 radio signal prevention circuit for other party signal Cu control unit Sas reference audio signal Sai received audio signal San pseudo audio signal Sm speaker Voice Smo Speaker signal Smoe Estimated error signal Sr Opposite speaker signal Cd Control signal Cs Hand-free operation signal

Claims (1)

[Scope of utility model registration request] 1. A hand-free telephone for a car telephone used in an automobile equipped with an audio device such as a radio or a car stereo, and an audio signal erasing circuit which is activated by a hands-free operation signal given from a control unit of the telephone ( 20), which is connected between the control unit and the audio signal erasing circuit, is activated by the hands-free operation signal, and prevents the wraparound of the other party's voice. A circuit (50), the audio signal erasing circuit uses an adding means (31) for outputting a difference signal between the output of the hands-free microphone and the output of the adaptive filter, and an audio signal from the audio device as a reference signal, Coefficients are updated according to the difference signal output of the adding means. A hands-free telephone for a car telephone, comprising the adaptive filter.