JPH0722364B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus that allows a video tape recorder to function also as a recording tape recorder.

(Prior Art) In recent years, in a video tape recorder, a method has been adopted in which an FM-modulated audio signal is recorded at high speed on the same tape track as that of the video signal by a rotary head to remarkably improve the sound quality of reproduced audio. .

FIG. 2A shows the structure of a recording circuit in a conventional magnetic recording / reproducing apparatus, for example, a video tape recorder.
1 is a waveform shaping circuit for shaping the waveform of an input audio signal, 2
Is an FM modulation circuit that FM-modulates the waveform-shaped audio signal, 3
Is a rotary head for recording the FM-modulated audio signal in the audio signal recording area of the tape 4, 5 is a waveform shaping circuit for shaping the waveform of the input video signal, and 6 is an FM modulation circuit for FM-modulating the waveform shaped video signal. , 7 are rotary heads for recording the FM-modulated video signal in the video signal recording area of the tape 4.

In the conventional example configured as described above, when an audio signal and a video signal are input, the audio signal is waveform-shaped by the waveform shaping circuit 1, FM-modulated by the FM modulation circuit 2, and then the tape 4 is recorded by the rotary head 3. It is recorded in the audio signal recording area.
At the same time, the video signal is waveform-shaped by the waveform shaping circuit 5, FM-modulated by the FM modulation circuit 6, and then recorded in the video signal recording area of the tape 4 by the rotary head 7.

Further, FIG. 2 (b) shows the structure of a reproducing circuit in a conventional magnetic recording / reproducing apparatus, for example, a video tape recorder, in which 8 also reproduces an FM-modulated audio signal from the audio signal recording area of the tape 4. A rotary head, 9 is an FM demodulation circuit that FM demodulates an FM-modulated audio signal, and 10 is a waveform shaping circuit that waveform-shapes the FM-demodulated audio signal and outputs the audio signal,
Reference numeral 11 is a rotary head for reproducing the FM-modulated video signal from the video signal recording area of the tape 4, 12 is an FM demodulation circuit for FM demodulating the FM-modulated video signal, and 1 is a waveform shaping for the FM-demodulated video signal. Is a waveform shaping circuit that outputs a video signal.

In the conventional example thus configured, when the tape 4 is run, the FM-modulated audio signal reproduced from the audio signal recording area of the tape 4 by the rotary head 8 is FM demodulated by the FM demodulation circuit 9, The waveform is shaped by the waveform shaping circuit 10 and then output as an audio signal. At the same time, the rotating head 11
Is reproduced from the video signal recording area of the tape 4 by
The FM-modulated video signal is FM-demodulated by the FM demodulation circuit 12, waveform-shaped by the waveform shaping circuit 13, and then output as a video signal.

(Problems to be Solved by the Invention) By the way, with a conventional video tape recorder, a tape 4 in which an audio signal is recorded in an audio signal recording area but a video signal is not recorded in the video signal recording area is used. When played back, a normal television device outputs only sound.

However, in a television device with an audio muting circuit, unless a video signal is input, the audio signal reproduction function stops and the audio signal is not output either, so that the video tape recorder cannot function as a recording tape recorder. There was a problem.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a magnetic recording / reproducing apparatus capable of outputting only audio even in a television apparatus having an audio muting circuit.

(Means for Solving Problems) According to the present invention, it is determined whether or not a video signal is input during recording of an audio signal, and when the video signal is not input, the sync signal generation circuit attached thereto outputs the signal. The synchronizing signal is simultaneously recorded in the video signal recording area of the tape.

(Operation) When the tape is played back, the audio signal is played back from the audio signal recording area and the video signal is played back from the video signal recording area, and the audio muting circuit does not operate. Therefore, even in a television device with an audio muting circuit. Only voice can be output.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 (a) shows the structure of a recording circuit according to an embodiment of the present invention. The same reference numerals as those in FIG. 2 (a) denote the same parts, and 14 denotes horizontal synchronization. A horizontal synchronizing signal generation circuit for outputting a signal, 15 determines whether or not a video signal is input to the waveform shaping circuit 5, and a changeover switch
A discriminating circuit that outputs either the waveform-shaped video signal or the horizontal synchronizing signal by switching 16; 17 is an FM modulation circuit that FM-modulates the waveform-shaped video signal or the horizontal synchronizing signal; 18 is an FM The rotary head records a modulated video signal or a horizontal synchronizing signal on the tape 4.

In this embodiment having such a configuration, when the audio signal is input to the waveform shaping circuit 1 and the video signal is input to the waveform shaping circuit 5, the changeover switch 16 is switched by the determination circuit 15, and the waveform shaping circuit 5 and FM are input. The modulation circuit 17 is connected. Therefore, the voice signal is waveform-shaped by the waveform shaping circuit 1 and FM-modulated by the FM modulation circuit 2 as in the conventional example.
It is recorded in the audio signal recording area of the tape 4 by the rotary head 3. At the same time, the video signal is waveform-shaped by the waveform shaping circuit 5 as in the conventional example, FM-modulated by the FM modulation circuit 17, and then recorded in the video signal recording area of the tape 4 by the rotary head 18. However, if the video signal is not input to the waveform shaping circuit 5, the discrimination circuit 15 causes the changeover switch.
Since 16 is switched and the horizontal synchronizing signal generating circuit 14 and the FM modulating circuit 17 are connected, the horizontal synchronizing signal FM-modulated by the FM modulating circuit 17 is recorded by the rotary head 18 in the video signal recording area of the tape 4. To be done.

Further, FIG. 1 (b) shows the structure of the reproducing circuit in one embodiment of the present invention, the same reference numerals as those in FIG. 2 (b) indicate the same parts, and 19 is A rotary head that reproduces an FM-modulated video signal or a horizontal synchronization signal from the video signal recording area of the tape 4, 20 is an FM demodulation circuit that demodulates the FM-modulated video signal or the horizontal synchronization signal, and 21 is an FM demodulation A waveform shaping circuit that waveform-shapes a video signal or a horizontal sync signal and outputs a video signal or a horizontal sync signal. 22 is a vertical sync signal generation circuit that outputs a vertical sync signal in synchronization with a rotary head switching signal. 23 is a waveform shaper. A discrimination circuit for discriminating whether or not there is a vertical synchronizing signal in the signal input to the circuit 5 and turning on / off the changeover switch 24. 25 is a signal outputted from the waveform shaping circuit 21 via the changeover switch 24. Vertical sync signal It is an adder that superimposes the vertical synchronization signal output from the raw circuit 22.

In the present embodiment having such a configuration, when the tape 4 is run, the FM-modulated audio signal reproduced from the audio signal recording area of the tape 4 by the rotary head 8 is FM demodulated by the FM demodulation circuit 9. The waveform is shaped by the waveform shaping circuit 10 and then output as an audio signal. At the same time, the FM-modulated video signal or horizontal sync signal reproduced from the video signal recording area of the tape 4 by the rotary head 19 is
The FM demodulation circuit 12 performs FM demodulation and the waveform shaping circuit 13 shapes the waveform. When the FM demodulation circuit 12 outputs the FM demodulated video signal, the determination circuit 23 determines the vertical synchronization in the video signal. Since the signal is discriminated and the changeover switch 24 is turned off, the waveform-shaped video signal is directly output from the adder 25. However, when the FM demodulation circuit 12 is outputting the FM demodulated horizontal sync signal, the discrimination circuit
Since the vertical sync signal cannot be distinguished for 23, the changeover switch 24
Is turned on to output the vertical synchronizing signal, the vertical synchronizing signal is superimposed on the waveform-shaped horizontal synchronizing signal by the adder 25 and output.

(Effects of the Invention) As described above, according to the present invention, if a video signal is not input during recording of audio only, the synchronization signal is recorded in the video signal recording area of the tape and is output during reproduction. Therefore, only the audio can be output even in the television device having the circuit for controlling the audio output depending on the presence / absence of the video signal.

Further, when the tape in which the horizontal synchronizing signal is recorded in the video signal recording area is reproduced, the vertical synchronizing signal is superimposed, so that the switching noise can be prevented from being generated on the screen of the television device.

[Brief description of drawings]

1A is a block diagram of a recording circuit according to an embodiment of the present invention, FIG. 1B is a block diagram of a reproducing circuit according to an embodiment of the present invention, and FIG. 2A is a conventional magnetic field. FIG. 2B is a block diagram of the recording circuit in the recording / reproducing apparatus, and FIG. 2B is a block diagram of the reproducing circuit in the conventional magnetic recording / reproducing apparatus. 4 ... tape, 14 ... synchronization signal generation circuit, 15 ... discrimination circuit, 16 ... selection switch.

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus capable of recording video and audio or only audio on a tape, comprising a sync signal generating circuit for outputting a sync signal, and an input video signal or the sync signal. The changeover switch means for outputting and whether or not the video signal is inputted are discriminated, and when the video signal is not inputted, the synchronizing signal is outputted from the changeover switch means, and the video tape is outputted together with the audio signal. A magnetic recording / reproducing apparatus comprising: a discriminating circuit for recording the synchronization signal.