JP3095553U - Audio signal circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To select one of audio signals of stereo signals from a plurality of AV apparatuses having different dynamic ranges incorporated in a composite AV apparatus, convert the selected audio signals into monaural audio signals, and perform RF signal conversion. To output a monaural audio signal and an audio signal of a selected stereo signal line signal. SOLUTION: One of the audio signals of the stereo signal from the composite AV device is selected, the audio signal of the selected stereo signal is mixed and converted to a monaural audio signal, and the signal level of the audio signal is automatically adjusted. After the adjustment, the converted monaural audio signal is amplified, and the amplified monaural audio signal is frequency-modulated, converted to an RF signal, and output. Further, one of the audio signals of the stereo signal from the composite AV device is selected, and the audio signal of the selected stereo signal is amplified to output the audio signal of the line signal.

Description

[Detailed description of the device]

[0001]

TECHNICAL FIELD The present invention relates to a DVD (Digital Versati). le Disk) device and VCR (Video Cassette Record) er) device and a combined AV (Audio-Visual) device incorporated therein. , A reproduced stereo signal is converted into a monaural signal RF (Radio Freq. The present invention relates to an audio signal circuit for converting and outputting an audio signal.

[0002]

2. Description of the Related Art A video signal and an audio signal reproduced by a composite AV device are respectively provided. Video sound that is input to the line input terminal of the TV device and played by the composite AV device You can listen to the voice. In addition, the video signal and sound reproduced by the composite AV device A voice signal and a free channel of TV broadcasting, for example, 1 channel or 3 channels. Channel to the RF input signal and input to the antenna input terminal of the TV device, It is also possible to view the reproduced video and audio reproduced by the device. But the signal Input a high level audio signal to the RF modulator and convert it into an RF audio signal However, when input to the antenna input terminal of the TV device, the audio signal interferes with the video signal. Then, there is a problem that the image displayed on the television device is distorted. Therefore, It is possible to directly input an audio signal with a large dynamic range to the RF modulator. Didn't come In addition, a composite AV device with a different dynamic range can be used. Convert audio signals from several AV devices into monaural audio signals of RF signals When outputting to a Levi device, a signal that the audio signal does not interfere with the video signal and the video signal is not distorted Signal level of the reproduced audio signal must be adjusted to the signal level There was a problem.

As a conventional technique, one of audio signals from a plurality of video / audio signal sources is used. Select one, adjust the level of the selected signal and memorize the adjusted volume level However, no matter which of the multiple audio signal sources is selected, the proper volume is always obtained. There was a thing (for example, refer patent document 1).

Further, it is determined whether the input signal is a stereo signal or a monaural signal. If the input signal is a stereo signal, that signal is output as a through signal as it is. Output, and if the input signal is a monaural signal, that signal becomes a pseudo stereo signal. Converted and output the converted signal as a pseudo stereo signal to the outside There was (for example, refer to Patent Document 2).

The first from the input stereo audio bitstream , The signals on the frequency axis corresponding to the second channel are respectively decoded and decoded. The signals on the frequency axis corresponding to the first and second channels are generated, and the generated signals are generated. It is also possible to convert the signal on the frequency axis for normal to the signal on the time axis and output it. There was a problem (see Patent Document 3, for example).

[0006]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-112145

[Patent Document 2] Japanese Unexamined Patent Publication No. 2002-118897

[Patent Document 3] Japanese Patent Laid-Open No. 2002-169593

[0007]

[Problems to be Solved by the Invention] However, among those described in the prior art, In the first one, select one of the audio signals from multiple video / audio sources Adjust the level of the selected signal, store the adjusted volume level, Ensure proper volume at all times regardless of which audio source is selected However, the signal level is stored for each of the multiple audio signal sources, and the selected audio signal is stored. The problem is that you have to adjust the signal level stored for each source. It was

In the following, the input signal is a stereo signal or a mono signal. If the input signal is a stereo signal, the signal is passed through. If the input signal is a monaural signal, it is output as it is, and the signal is simulated. Convert to a similar stereo signal and output the converted signal as a pseudo stereo signal to the outside. Input the audio signal with high signal level to the RF modulator. When converted to an audio signal of the RF signal and input to the antenna input terminal of the TV device , The problem that the image displayed on the TV device is distorted by the interference of the audio signal with the video signal. It did not solve the subject.

Further, in the following, the input stereo audio is used. The signals on the frequency axis corresponding to the first and second channels are transmitted from the bitstream. Each is decoded and the signals on the frequency axis corresponding to the decoded first and second channels are decoded. Signal and convert the generated signal on the frequency axis for monaural to a signal on the time axis However, similarly to the above, an audio signal with a high signal level was It is input to the dulator and converted into an audio signal of the RF signal and input to the antenna of the TV device. When input to the terminal, the audio signal interferes with the video signal and is displayed on the TV device. It did not solve the problem that the image was distorted.

The present invention has been made in view of the above problems of the prior art. The purpose of this is the dynamics built into the composite AV device. Select one of the audio signals of stereo signals from a plurality of AV devices with different cleanses Convert it to a monaural audio signal and output an RF monaural audio signal. Audio signal of the line signal of the selected stereo signal that can be output It is intended to provide an audio signal circuit capable of outputting

[0011]

In order to achieve the above-mentioned object, a voice according to the present invention is used. The signal circuit is used for the audio signal of one channel of the first stereo signal or the second stereo signal. A first changeover switch for selecting an audio signal of one channel of the stereo signal, Audio signal of the other channel of the first stereo signal, or the second stereo signal Second selector switch for selecting the audio signal of the other channel of the The audio signal selected by the changeover switch and the sound signal selected by the second changeover switch. And a MIX circuit that mixes the audio signal with the converted audio signal into a monaural audio signal, The monaural signal converted by the MIX circuit is automatically adjusted by adjusting the signal level of the signal. A first amplifying circuit for amplifying the voice signal of the signal, and amplified by the first amplifying circuit. The audio signal of the monaural signal is frequency-modulated and converted into the RF signal, and the audio signal of the RF signal is converted. And an RF modulator that outputs a signal.

Also, an audio signal of one channel of the first stereo signal, or Or a third selector switch for selecting the audio signal selected by the first selector switch. Switch and the audio signal of the other channel of the first stereo signal, or A fourth changeover switch for selecting the audio signal selected by the second changeover switch; , The sound of the line signal by amplifying the audio signal selected by the third changeover switch. Selected by the second amplifier circuit for outputting a voice signal and the fourth changeover switch A third amplifier circuit for amplifying the audio signal and outputting the audio signal of the line signal .

With the above-mentioned configuration, the DA built in the composite AV apparatus is One of audio signals of stereo signals from multiple AV devices with different dynamic ranges Select to convert the monaural signal to the audio signal and convert the RF signal to the monaural signal audio. It is possible to output the signal and the line signal of the selected stereo signal. An audio signal can be output.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings as appropriate. To do. FIG. 1 is a block diagram showing a configuration of an audio signal circuit according to an embodiment of the present invention. 2 is an audio signal circuit according to an embodiment of the present invention. 2 is a block diagram showing the configuration of an embodiment of an audio signal circuit according to the present invention. FIG.

First, the configuration of the audio signal circuit according to the embodiment of the present invention in FIG. 1 will be shown. Description will be given based on a block diagram.

The audio signal circuit 10 is an audio signal of one channel of a stereo signal. Through input terminal P1 for amplifying and outputting the signal and the other channel of the stereo signal. A through input terminal P2 for amplifying and outputting a channel audio signal, and a stereo signal The input terminal P3 for inputting the audio signal of one channel and the other of the stereo signals Input terminal P4 for inputting the audio signal of this channel and one channel of the stereo signal Amplify the audio signal of the channel and output the audio signal of the line signal to the line output terminal P5 And the amplifier circuit 11 for amplifying the audio signal of the other channel of the stereo signal. An amplifier circuit 12 for outputting an in-audio signal to the line output terminal P6, and a stereo circuit A MIX circuit 13 that mixes the audio signals of the signals and converts the audio signals into a monaural audio signal; , ALC (Autom) that automatically adjusts the signal level of the audio signal and amplifies the audio signal atic level control) built-in amplifier circuit 14 and audio signal Number-modulate and convert to RF signal, and output audio signal of RF signal to RF output terminal P7 RF modulator 15 and an input signal from the through input terminal P1 or an input terminal From the switch K1 for selecting the input signal from the child P3 and the through input terminal P2 Changeover switch K2 for selecting the input signal of or the input signal from the input terminal P4. , Input signal from the through input terminal P1 or selected by the changeover switch K1 Input signal from the through input terminal P2 and the changeover switch K3 for selecting the input signal Alternatively, the changeover switch K for selecting the input signal selected by the changeover switch K2 It is composed of 4 and.

The operation of the audio signal circuit configured as described above will be described below. And explain.

Stereo input to the through input terminal P1 and the through input terminal P2 The audio signal of the signal is mixed and converted into the audio signal of the monaural signal of the RF signal and the RF signal is output. When outputting from the force terminal P7, the changeover switch K1 and the changeover switch K2 are respectively set. Switch to the A side. Changeover switch K1 and changeover switch K2 are switched to A side respectively. When replaced, one channel of the stereo signal input to the through input terminal P1 Channel audio signal and the other channel of the stereo signal input to the through input terminal P2. The channel audio signal is mixed by the MIX circuit 13 into a monaural audio signal. The signal level of the audio signal is converted and automatically adjusted by the ALC built-in amplifier circuit 14. The audio signal of the monaural signal is amplified by the RF modulator 15 and the monaural signal is transmitted. The audio signal of the signal is frequency-modulated and converted into an RF signal, which is a monaural signal of the RF signal. Is output from the RF output terminal P7.

Audio signals of stereo signals input to the input terminals P3 and P4 Signal is mixed and converted into an audio signal of a monaural signal of the RF signal, and the RF output terminal P7 Output from the switch, switch the changeover switch K1 and the changeover switch K2 to the B side respectively. Change. The changeover switch K1 and the changeover switch K2 are respectively changed over to the B side. And the audio signal of one channel of the stereo signal input to the input terminal P1 The audio signal of the other channel of the stereo signal input to the input terminal P2 is MIX It is mixed by the circuit 13 and converted into a monaural audio signal, and ALC built-in amplification The signal level of the audio signal is automatically adjusted by the circuit 14 so that the audio signal of the monaural signal is obtained. Is amplified, and the RF modulator 15 frequency-modulates the monaural audio signal. RF signal is converted into RF signal, and RF output as audio signal of monaural signal of RF signal It is output from the terminal P7.

Stereo input to the through input terminal P1 and the through input terminal P2 Line output terminal P5 and line output as the audio signal of the signal as the audio signal of the line signal When outputting from the terminal P6 respectively, the changeover switch K3 and the changeover switch K4 To the A side respectively. When the changeover switch K3 is switched to the A side, the switch The audio signal of one channel of the stereo signal input to the route input terminal P1 is increased. Amplified by the width circuit 11 and output from the line output terminal P5, and the through input terminal The audio signal of the other channel of the stereo signal input to P2 is input to the amplifier circuit 12. It is further amplified and output from the line output terminal P6.

Audio signals of stereo signals input to the input terminals P3 and P4 The line output terminal P5 and the line output terminal P6 as audio signals of the line signal. When each of them is output, the changeover switch K1 and the changeover switch K3 are respectively set to B. To the B side and switch the changeover switch K2 and the changeover switch K4 to the B side respectively. Get The changeover switch K1 and the changeover switch K3 are respectively switched to the B side. And the audio signal of one channel of the stereo signal input to the input terminal P3 increases. The signal is amplified by the width circuit 11 and output from the line output terminal P5. 2 and the changeover switch K4 are respectively switched to the B side, the input terminal P4 is turned on. The audio signal of the other channel of the input stereo signal is amplified by the amplifier circuit 12. And output from the line output terminal P6.

Next, one example of the audio signal circuit according to the embodiment of the present invention shown in FIG. Description will be given based on a block diagram showing the configuration.

The composite AV device 20 equipped with the audio signal circuit 10 is recorded on a DVD. DVD device 21 for reproducing the recorded audio / video signal and the image recorded on the video cassette. It controls the system of the VCR device 22 that reproduces the image / audio signal and the composite AV device 20. And a microcomputer 24.

The audio signal of the right channel of the stereo signal from the DVD device 21 is output. The left channel of the stereo signal input to the through input terminal P1 of the voice signal circuit 10 Is input to the through input terminal P2 of the audio signal circuit 10. Also, The audio signal of the right channel of the stereo signal from the VCR device 22 is the audio signal circuit 1 0 is input to the input terminal P3, and the audio signal of the left channel of the stereo signal is the audio signal. The signal is input to the input terminal P4 of the signal circuit 10.

Television device for viewing video and audio reproduced by the composite AV device 20 30 receives the RF signal input to the antenna input terminal T1 and outputs a voice signal Of the audio signal of the monaural signal received by the receiving circuit 31 Input and input of the audio signal of the stereo signal input to the line input terminals T1 and T2 Select and amplify the audio signal of the selected input signal to output the sound from the speakers 33 and 34. It is composed of an audio signal amplifier circuit 32 that outputs a voice.

The composite AV apparatus 20 and the television apparatus 30 are connected to the audio signal circuit 10. Output terminal P5 is the right channel of the audio signal amplifier circuit 32 of the television device 30. The line output terminal P6 of the audio signal circuit 10 is connected to the IN input terminal T2, and Connected to the line input terminal T3 of the left channel of the audio signal amplifier circuit 32 of the device 30 The RF output terminal P7 of the audio signal circuit 10 is connected to the receiving circuit 31 of the television device 30. Is connected to the antenna input terminal T1. It should be noted that the composite AV device 20 and the TV device The unit 30 includes a video signal circuit, but is not shown.

An embodiment of the audio signal circuit configured as above will be described below. The operation will be described with reference to FIG.

The audio signal of the stereo signal reproduced by the DVD device 21 is transmitted as an RF signal. No. 1 monaural signal is converted into an audio signal and the antenna input terminal T1 of the television device 30 is converted. Input to the speaker 33, 34 to output a monaural sound. Then, the microcomputer 24 switches the changeover switch K1 and the changeover switch K2 to A, respectively. Switch to the side. Switch the changeover switch K1 and the changeover switch K2 to the A side respectively. If replaced, the stereo from the DVD device 21 input to the through input terminal P1 The audio signal of the right channel of the signal and the DVD device 2 input to the through input terminal P2 The left channel audio signal of the stereo signal from 1 is input to the MIX circuit 13. , The MIX circuit 13 mixes the audio signals of the stereo signals to produce the sound of the monaural signals. It is converted into a voice signal and the signal level of the voice signal is automatically adjusted by the ALC built-in amplifier circuit 14. The adjusted audio signal of the monaural signal is amplified, and the RF modulator 15 monitors the audio signal. The sound signal of the noral signal is frequency-modulated and converted into the RF signal, and the The audio signal of the Ral signal is output from the RF output terminal P7 and is input to the antenna input terminal T1. Entered in. Sound of monaural signal of RF signal input to antenna input terminal T1 The voice signal is received by the receiving circuit 31, and the received monaural signal voice signal is output. A monaural sound is amplified from the speakers 33 and 34 by being amplified by the voice signal amplifier circuit 32. Is output.

Further, the audio signal of the stereo signal reproduced by the VCR device 22 is The RF signal is converted into a monaural signal and converted into an audio signal, and the antenna input terminal of the television device 30 is converted. The mode in which the sound is input to the child T1 and the monaural sound is output from the speakers 33 and 34 is When selected, the microcomputer 24 switches the changeover switch K1 and the changeover switch K2. Switch to B side respectively. The changeover switch K1 and the changeover switch K2 are respectively on the B side. To the stereo from the VCR device 22 input to the input terminal P1. From the audio signal of the right channel of the signal and the VCR device 22 input to the input terminal P2 The left-channel audio signal of the stereo signal of is input to the MIX circuit 13, The X circuit 13 mixes the audio signals of the stereo signals to obtain the audio signals of the monaural signals. And the signal level of the audio signal is automatically adjusted by the ALC built-in amplifier circuit 14. The audio signal of the monaural signal is amplified and monaural by the RF modulator 15. The audio signal of the signal is frequency-modulated and converted into the RF signal, and the monaural signal of the RF signal is received. Is output from the RF output terminal P7 as an audio signal of the signal and input to the antenna input terminal T1. To be done. Audio signal of monaural signal of RF signal input to antenna input terminal T1 Is received by the receiving circuit 31, and the received audio signal of the monaural signal is an audio signal. Amplified by the amplifier circuit 32, monaural sound is output from the speakers 33 and 34. To be done.

Further, the audio signal of the stereo signal reproduced by the DVD device 21 is Input to the line input terminals T2 and T3 of the television device 30 as audio signals of line signals Then, when the mode for outputting stereo sound from the speakers 33 and 34 is selected , The microcomputer 24 switches the changeover switch K3 and the changeover switch K4 to the A side, respectively. Replace. The changeover switch K3 and the changeover switch K4 are changed to the A side respectively. Then, the stereo signal from the DVD device 21 input to the through input terminal P1 The audio signal of the right channel is input to the amplifier circuit 11 and amplified by the amplifier circuit 11. DVD output from the line output terminal P5 and input to the through input terminal P2 The audio signal of the left channel of the stereo signal from the device 21 is input to the amplifier circuit 12. Is amplified by the amplifier circuit 12 and output from the line output terminal P6. It is input to the line input terminal T1 and the line input terminal T2 of the device 30, respectively. La Of the stereo signals input to the IN input terminal T1 and the line input terminal T2, respectively. The audio signals are respectively amplified by the audio signal amplifier circuit 32, and the speaker 33, 34 outputs a stereo signal sound.

Further, the audio signal of the stereo signal reproduced by the VCR device 22 is Input to the line input terminals T2 and T3 of the television device 30 as audio signals of line signals Then, when the mode for outputting stereo sound from the speakers 33 and 34 is selected , The microcomputer 24 switches the changeover switch K1 and the changeover switch K3 to the B side, respectively. In exchange, the changeover switch K2 and the changeover switch K4 are respectively changed over to the B side. When the changeover switch K1 and the changeover switch K3 are respectively changed to the B side, The right channel sound of the stereo signal from the VCR device 22 input to the input terminal P3. The voice signal is input to the amplifier circuit 11, is amplified by the amplifier circuit 11, and is output to the line output terminal. It is output from the child P5 and input to the line input terminal T1 of the television device 30. Also, When the changeover switch K2 and the changeover switch K4 are respectively changed to the B side, The left channel sound of the stereo signal from the VCR device 22 input to the input terminal P4 The voice signal is input to the amplifier circuit 12, is amplified by the amplifier circuit 12, and is output to the line output terminal. It is output from the child P6 and input to the line input terminal T2 of the television device 30. line Audio of stereo signals input to the input terminal T1 and the line input terminal T2, respectively The signals are respectively amplified by the audio signal amplifier circuit 32, and the speakers 33, 34 Outputs a stereo signal sound.

The embodiment of the present invention has been described in detail above, but the present invention is not limited to this. Of course, modifications and improvements can be made within the ordinary knowledge of those skilled in the art. For example, 2 Select the audio signals of the three stereo signals, and select the audio signals of the RF signal and the line. The output of the audio signal and the signal has been explained, but the sound of multiple stereo signals The voice signal is selected by the multi-contact changeover switch, and the voice signal of the RF signal is selected. You may make it output the audio | voice signal of a line signal.

[0033]

As described above, according to the audio signal circuit of the present invention, Select one of the audio signals of the stereo signal from the composite AV device and select the selected audio signal. The audio signal of the Leo signal is mixed and converted into the audio signal of the monaural signal, and the signal of the audio signal is mixed. The signal level is automatically adjusted to amplify and convert the converted monaural audio signal. The audio signal of the generated monaural signal is frequency-modulated and converted into an RF signal, An audio signal can be output. Also, the sound of the stereo signal from the composite AV device Select one of the voice signals and amplify each of the selected stereo signal's voice signals. The audio signal of the line signal can be output. This allows the composite AV equipment From a plurality of AV devices with different dynamic ranges built into the equipment Select one of the audio signals of the No. signal and convert it to a monaural audio signal, It is possible to output a monaural audio signal and select the selected stereo. The audio signal of the line signal of the signal can be output.

The audio signal circuit according to the first aspect of the present invention is provided with the first stereo signal. Select the audio signal or the audio signal of the second stereo signal and select the selected stereo. The audio signal of the O signal is mixed and converted into the audio signal of the monaural signal, and the signal of the audio signal The level is automatically adjusted to amplify the converted monaural audio signal and Sound signal of monaural signal is frequency-modulated and converted into RF signal, It is possible to output a voice signal, and the voice of the first stereo signal is output. Signal, or the audio signal of the second stereo signal, and the selected stereo signal It is possible to output each line signal audio signal by amplifying each audio signal I am sorry.

The audio signal circuit according to the second aspect of the present invention is the audio signal circuit for the first stereo signal. Select the audio signal or the audio signal of the second stereo signal and select the selected stereo. The audio signal of the O signal is mixed and converted into the audio signal of the monaural signal, and the signal of the audio signal The level is automatically adjusted to amplify the converted monaural audio signal and Sound signal of monaural signal is frequency-modulated and converted into RF signal, A voice signal can be output.

An audio signal circuit according to a third aspect of the present invention is the audio signal circuit for a first stereo signal. Select the audio signal or the audio signal of the second stereo signal and select the selected stereo. It is possible to amplify the audio signal of each signal and output the audio signal of line signal. I am trying to do it.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an audio signal circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an example of an audio signal circuit according to an embodiment of the present invention.

[Explanation of symbols]

10 Audio signal circuit 11, 12 amplifier circuit 13 MIX circuit 14 ALC built-in amplifier circuit 15 RF modulator K1, K2, K3, K4 selector switch P1, P2 through input terminals P3, P4 input terminals P5, P6 line output terminals P7 RF output terminal 20 Compound AV equipment 21 DVD device 22 VCR device 24 Microcomputer 30 TV equipment 31 Receiver circuit 32 audio signal amplifier circuit 33, 34 speakers T1 antenna input terminal T2, T3 line input terminals

Claims (3)

[Scope of utility model registration request] 1. A first changeover switch for selecting an audio signal of one channel of a first stereo signal or an audio signal of one channel of a second stereo signal, and a first switch.
Second changeover switch for selecting the audio signal of the other channel of the stereo signal or the audio signal of the other channel of the second stereo signal, and the audio signal of the one channel of the first stereo signal, or A third selector switch for selecting the audio signal selected by the first selector switch, an audio signal of the other channel of the first stereo signal, or an audio signal selected by the second selector switch. A fourth changeover switch to
A MIX circuit that mixes the audio signal selected by the first changeover switch and the audio signal selected by the second changeover switch to convert the audio signal into a monaural signal, and automatically adjusts the signal level of the audio signal. Then, the MIX
A first amplifier circuit that amplifies the audio signal of the monaural signal converted by the circuit, and frequency-modulates the audio signal of the monaural signal amplified by the first amplifier circuit to convert it into an RF signal, and the audio of the RF signal. An RF modulator that outputs a signal, a second amplifier circuit that amplifies the audio signal selected by the third changeover switch and outputs an audio signal of a line signal, and an audio selected by the fourth changeover switch. An audio signal circuit comprising: a third amplifier circuit for amplifying a signal and outputting an audio signal of a line signal. 2. A first changeover switch for selecting an audio signal of one channel of the first stereo signal or an audio signal of one channel of the second stereo signal, and a first switch.
Second changeover switch for selecting the sound signal of the other channel of the stereo signal or the sound signal of the other channel of the second stereo signal, the sound signal selected by the first changeover switch, and the second And a MIX circuit for mixing the audio signal selected by the selector switch and converting it into a monaural audio signal, and automatically adjusting the signal level of the audio signal to convert the monaural audio signal converted by the MIX circuit. A first amplifier circuit for amplifying; and an RF modulator for frequency-modulating the audio signal of the monaural signal amplified by the first amplifier circuit to convert it into an RF signal and outputting the audio signal of the RF signal. A voice signal circuit characterized by. 3. A third selector switch for selecting an audio signal of one channel of the first stereo signal or an audio signal selected by the first selector switch,
A fourth changeover switch for selecting the sound signal of the other channel of the first stereo signal or a sound signal selected by the second changeover switch, and a sound signal selected by the third changeover switch. A second amplifier circuit that amplifies and outputs a line signal audio signal;
The audio signal circuit according to claim 2, further comprising a third amplifier circuit for amplifying the audio signal selected by the changeover switch and outputting the audio signal of the line signal.