JP2864790B2 - Recording audio switching circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recorded audio signal switching circuit in a VCR (video cassette recorder) having a stereo audio track.

[0002]

2. Description of the Related Art Conventionally, as a technique in this field, a technique in which only main audio is taken out from an audio multiplex demodulation circuit and used as a normal track signal is used, and a signal from an external input terminal is recorded. In such a case, it has been the mainstream that the main audio from the audio multiplex demodulation circuit and a signal passed through a circuit for synthesizing a normal track signal provided exclusively for an external input terminal are switched by a switch.

[0003]

However, in the circuit having the above configuration, a switching circuit for a normal track audio signal is required in addition to the two-channel audio signal switching circuit for the main audio and the sub audio. It becomes complicated and also routes many signal lines.

[0004] It is an object of the present invention to eliminate the above-mentioned problems and to provide a recorded audio switching circuit capable of synthesizing audio signals of a normal track with a simple circuit configuration.

[0005]

According to the present invention, in order to solve the above-mentioned problems, in a two-channel audio signal selected by a signal selection switch, only the right channel can be independently muted. The left and right channels are added, and in the audio multiplexing mode of the television broadcast, the mute state of the signal of the right channel is switched to synthesize the signal of the normal track.

[0006]

According to the present invention, as described above, the right channel audio signal that can be silenced and the left channel audio signal that is not silenced are added by the left and right signals selected by the signal changeover switch, and 2 The right channel is muted during multilingual broadcasting, and is not muted during stereo broadcasting, so that it is used as a normal track audio signal.Therefore, no separate signal changeover switch is required for normal tracks, and the accompanying audio signal The noise due to the routing of the wire can be suppressed and the configuration can be made at low cost. It should be noted that mute is not normally performed during external input.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a recording audio signal switching circuit according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a recording audio signal switching circuit according to an embodiment of the present invention. It is a block diagram.

In FIG. 1, 1 is a signal changeover switch, 2 is a left channel audio output terminal, 3 is a right channel audio output, 4, 6, and 7 are impedance conversion circuits, 5 is a mute circuit, 8 is an addition circuit, and 9 is an addition circuit. Normal track audio signal output terminal.

First, when the audio signal selected by the changeover switch 1 is an audio signal of a stereo broadcast, the mute circuit 5 is not operated and the output of the circuit 4 is directly input to the circuit 6 and the adder circuit 8 is operated. Then, the left and right audio signals are added and output from a normal track audio output terminal as a monaural audio signal. Next, when the selected audio signal is an audio signal of a bilingual broadcast, no signal is output from the circuit 6 in order to operate the mute circuit 6, and the left channel audio which is the main audio is output from the output terminal 9. Only the signal is output.

In FIG. 2, reference numeral 10 denotes a signal switching integrated circuit having two output terminals, 11 denotes an impedance conversion circuit, and 12 denotes an addition circuit.

First, when the audio signal selected by the 10 integrated circuits is an audio signal of a stereo broadcast, the mute circuit in the integrated circuit is not operated, and the same right channel audio signal as 13 is output from the terminal 15. The output signal is added to the audio signal of the left channel of the terminal 14 which has passed through the circuit 16 by an adding circuit 17 and is output from the normal track audio output terminal 18 as a monaural audio signal. Next, if the selected audio signal is an audio signal of a bilingual broadcast, no signal is output from the terminal 15 to operate the muffling circuit in the integrated circuit, and the main audio left signal is output from the output terminal 18. Only the audio signal of the channel is output.

It should be noted that the present invention is not limited to the above embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0014]

As described above in detail, according to the present invention, since an audio signal for a normal track is created from an audio signal after signal selection, no extra changeover switch is required. The circuit configuration is simplified, and the configuration can be made inexpensively. In addition, noise is reduced because signal routing is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a recording audio signal switching circuit according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a recording audio signal switching circuit according to an embodiment of the present invention;

FIG. 3 is a schematic configuration diagram of a conventional circuit.

[Explanation of symbols]

Reference Signs List 1 signal changeover switch 2 left channel audio signal output terminal 3 right channel audio signal output terminal 4 low output resistance impedance conversion circuit 5 silence circuit 6 low output resistance impedance conversion circuit 7 low output resistance impedance conversion circuit 8 addition circuit 9 normal Audio signal output terminal for truck 10 Signal switching integrated circuit having two output terminals 11 Output terminal group capable of independent silencing 12 Non-silencing output terminal group 13 Right channel audio signal output terminal 14 Left channel audio signal output terminal 15 Right Channel audio signal output terminal 16 Impedance conversion circuit with low output resistance 17 Adder circuit 19 Audio signal output terminal for normal track

Claims (2)

(57) [Claims] 1. A signal changeover switch for two channels, three low output resistance impedance conversion circuits, a muffling circuit, and a signal addition circuit, wherein two output terminals of the signal changeover switch are connected to left and right of a stereo. The left and right signals are directly extracted from the output terminals thereof, and the left channel signal to which the impedance conversion circuit is connected and the impedance conversion circuit are connected, and the output of the impedance conversion circuit is input. A silencing circuit and a right channel signal to which the impedance conversion circuit having an output of the silencing circuit as an input are connected are added by the signal adding circuit to obtain a normal track audio signal, and the left and right signals are stereo. Addition without silencing, output as monaural signal, left and right signals are bilingual Performed the silencing of the right channel when the transmission of the signal, only the left channel is the main voice was characterized by the fact that output recorded voice switching circuit 2. An output terminal having two output terminals having a low output resistance.
A signal selection integrated circuit having two systems, an input signal switching circuit capable of independently muting only one of the output terminals, an impedance conversion circuit with a low output resistance, and a signal addition circuit; Distribute each system as stereo left and right channels, always output the left and right signals to the output terminal that can not mute, to the left channel of the output terminal that can mute and the right channel of the output terminal that can not mute The output of the connected impedance conversion circuit is used as a one-channel signal by the signal addition circuit. When the left and right signals are stereo, the signals are added without silencing and output as a monaural signal. A recorded audio switching circuit characterized in that when a bilingual broadcast signal is output, the right channel is muted and only the left channel, which is the main audio, is output.