JP3046109B2 - Video signal recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction in which a video signal is FM-modulated, and a digital audio signal (hereinafter referred to as "PCM audio signal") is recorded and reproduced in a time-division multiplex manner during a blanking period of the FM video signal. And a video signal recording and reproducing apparatus.

[0002]

2. Description of the Related Art FIG. 17 shows an example of a conventional video signal recording / reproducing apparatus which records and reproduces a PCM audio signal in a time-division multiplex manner in a part of a vertical blanking period of an FM-modulated video signal. Apparatus (hereinafter, referred to as VTR)
FIG. In the figure, reference numeral 1 denotes an A / D for converting an input video signal from an analog signal to a digital signal
The converter 2 is a first sync separation circuit for performing sync separation from the input video signal, and 3 is a recording signal processing circuit, which is based on the sync signal output from the first sync separation circuit 2 and serves as a reference. To perform recording signal processing such as insertion of blanking data. In the recording signal processing circuit 3, the FM
A timing pulse for inserting a PCM audio signal into a video signal is also generated and output. 4 is a D / A converter for converting a digital signal into an analog signal, 5 is a pre-emphasis circuit for emphasizing the high frequency component of the video signal, 6 is an FM modulator for FM modulating the video signal, and 7 is a PCM encoder. After performing a shuffling process, adding an error correction code, and the like to the input audio signal, the digital audio signal of one field period is converted into a signal of the FM modulator 6 based on the timing pulse output from the recording signal processing circuit 3. A time axis compression process is performed for insertion into a vertical blanking period of an FM video signal which is an output, and digitally modulated and output.
Reference numerals 8 and 9 denote switches, 10 an adder for adding the outputs of the switches 8 and 9, 11 a recording amplifier, 12a and 12b rotary heads, and 13 a magnetic tape.

[0003] Each of the rotary heads 12a and 16b has a rotary head 12a.
And a head amplifier for amplifying the reproduction signal from 12b,
A head switching circuit 17 for switching the outputs from the head amplifiers 16a and 16b based on a head switching signal;
Reference numeral 18 denotes a reproduction equalizer that compensates for the frequency characteristics of the reproduction FM video signal, 19 denotes a limiter that removes an amplitude fluctuation component of the reproduction FM video signal output from the reproduction equalizer 18, and 20
Is an FM demodulator, 21 is a de-emphasis circuit having the reverse characteristic of the pre-emphasis circuit 5 , 22 is a clamp circuit, 23 is an A / D converter for converting a reproduced video signal from an analog signal to a digital signal, 24 Is a second sync separation circuit that separates a sync signal from the playback video signal, and 25 is playback based on the sync separation signal output from the second sync separation circuit 24, such as time axis correction and dropout compensation of the playback video signal. A reproduction signal processing circuit for performing signal processing;
A / A converter 27 is a PCM decoder which detects the PCM audio signal of the one field period inserted in the vertical blanking period of the reproduction signal, and performs error correction, deshuffling processing, error correction processing, and the like. Restore and output audio signal.

FIG. 18 is a top view of a rotary head used in a VTR.
a rotating drum wherein b is mounted at 180 ° intervals,
15a and 15b are guide pins for winding the magnetic tape 13 around the rotary drum 14.

Next, the operation will be described. In the block diagram of FIG. 17, an input video signal is A / D-converted by an A / D converter 1 and then, in a recording signal processing circuit 3, based on a sync separation output from a first sync separation circuit 2. Recording signal processing such as insertion of blanking data is performed. The recording signal processing circuit 3 also generates and outputs a timing pulse for inserting a PCM audio signal into an FM video signal. The output of the recording signal processing circuit 3 is converted from a digital signal to an analog signal by a D / A converter 4 and input to a pre-emphasis circuit 5. The pre-emphasis circuit 5 emphasizes the high frequency component of the video signal and outputs it to the FM modulator 6. The FM modulator 6 performs FM modulation on the video signal. On the other hand, the audio signal is input to the PCM encoder 7 and subjected to shuffling processing, addition of an error correction code and the like, and then, based on the timing pulse output from the recording signal processing circuit 3, converts the digital audio signal for one field period into the above-mentioned signal. FM which is the output of the FM modulator 6
A time axis compression process is performed to insert the video signal during the vertical blanking period of the video signal, and the resultant signal is digitally modulated and output.

Thereafter, the PCM audio signal output from the PCM encoder 7 during the one field period is FM
For example, the modulated video signal (FM video signal) is inserted into the vertical blanking period at the timing shown in FIG. A timing pulse output from the recording signal processing circuit 3 is sent to the switches 8 and 9, and the FM video signal and the PCM audio signal are switched and added by the adder 10 to create a recording signal. Then, the recording amplifier 11 outputs the recording signal FM
The video signal and the PCM audio signal are amplified and the rotating head 12
a and 12b are recorded on the magnetic tape 13.

At this time, the magnetic tape 13 is
18, the recording is performed on the magnetic tape 13 even if the recording current always flows through the rotary heads 12 a and 12 b, because the rotary head is in contact with the magnetic tape 13. Only during the period. Therefore, the recording pattern on the magnetic tape 13 is recorded separately in two areas a and b as shown in FIG. 20, and the recording signal of one field is recorded on one track. In addition,
In the figure, a indicates a track recorded by the rotary head 12a, and b indicates a track recorded by the rotary head 12b. Also, since the PCM audio signal is recorded by time division multiplexing during the vertical blanking period of the FM video signal,
The portion where the PCM audio signal is recorded is the hatched portion.

Next, the operation at the time of reproduction will be described. The reproduced FM video signal reproduced from the rotary heads 12a and 12b and the PCM audio signal mixed at the time of recording are amplified by the head amplifiers 16a and 16b, respectively. A reproduced signal, which is an output of each of the head amplifiers 16a and 16b, is selected in a head switching circuit 17 based on the head switching signal from a rotating head in contact with the magnetic tape 13 as shown in FIG. And is switched to one reproduction signal (FIG. 21C). And
The playback signal from the head switching circuit 17 is sent to the playback equalizer 18 and to the PCM decoder 27. In the PCM decoder 27, the PCM of one field period inserted in the vertical blanking period of the reproduction signal is used.
The audio signal is detected, and error correction, deshuffling processing, error correction processing, and the like are performed to restore and output the original audio signal.

In general, when an FM signal is recorded and reproduced by an electromagnetic conversion system using a tape and a head, the lower sideband is emphasized, the upper sideband is suppressed, and the modulation index changes, and at the same time, the imbalance of the sideband occurs. Therefore, the reproduced FM signal corresponding to the rising portion (FIG. 22A) of the video signal in which the high-frequency component is emphasized by the pre-emphasis circuit 5 is
It is largely confined as shown in FIG. Therefore, the reproduction equalizer 18 suppresses the lower band and enhances the upper band to compensate for the frequency characteristics of the reproduced FM video signal with the frequency characteristics shown in FIG. Is reduced as shown in FIG. 22 (c). Then, the output of the reproduction equalizer 18 is sent to the limiter 19 to remove the amplitude fluctuation component of the reproduction FM video signal, and the output is as shown in FIG.

Next, the reproduced signal output from the limiter 19 is input to an FM demodulator 20 and FM-demodulated. Then, when the high frequency component emphasized at the time of recording is attenuated by the de-emphasis circuit 21, a reproduced video signal with reduced high frequency noise is obtained. Next, the reproduced video signal is input to the clamp circuit 22 and is clamped so as to have an input voltage level of the A / D converter 23. The clamp circuit 22 separates the synchronization signal of the reproduced video signal to generate a clamp pulse, and clamps the leading end of the synchronous signal of the reproduced video signal to a predetermined DC voltage level. The reproduced video signal clamped by the clamp circuit 22 is converted from an analog signal to a digital signal by an A / D converter 23 and sent to a reproduced signal processing circuit 25. Further, the second sync separation circuit 24 separates a sync signal from the reproduced video signal. The reproduction signal processing circuit 25 performs reproduction signal processing such as time axis correction and drop-out compensation on the reproduction video signal based on the sync separation output from the second sync separation circuit 24, and the D / A converter 26 The digital reproduction video signal is D / A converted and output.

[0011]

In the conventional video signal recording / reproducing apparatus as described above, during recording, a PCM audio signal is multiplexed and recorded in a time-division manner during a vertical blanking period of an FM-modulated video signal. During reproduction, the reproduced FM video signal and the mixed PCM audio signal are FM-demodulated as they are.
On the other hand, the PCM audio signal has a broadband signal component because it has a pulse waveform, so that the PCM audio signal band overlaps the video signal band as shown in FIG.
As described above, the reproduced FM video signal and the PCM audio signal are
After demodulation, the output waveform of the FM demodulator 20 becomes a signal waveform such as noise in the PCM audio signal area, as shown in FIG.

The reproduced signal shown in FIG.
Before demodulation, as shown in FIG. 26 (b), the FM video signal and the PCM audio signal in the reproduction signal are separated, and the reproduction FM video signal (FIG. The PCM audio signal area period in (b)) is a non-signal portion, and when the reproduced FM video signal having the non-signal portion is subjected to FM demodulation, FIG.
As shown in FIG. 6C, the FM demodulated waveform in the PCM audio signal area, which is a non-signal portion, becomes a signal waveform like noise.

On the other hand, if the clamp circuit 22 before the A / D converter 23 is configured to separate the synchronizing signal of the reproduced video signal and generate a clamp pulse to clamp the leading end of the synchronizing signal, If there is noise as shown in FIGS. 25 and 26 (c) in the middle PCM audio signal area, normal synchronization separation cannot be performed, and a clamp operation will be performed at the lower end of the noise portion in the PCM audio signal area.
There has been a problem that the signal level of the input reproduced video signal of the A / D converter 23 is not clamped to a normal value and the reproduced video signal is broken.

Further, in the PCM audio signal area of the reproduced video signal, it is not known how the output waveform of the FM demodulator 20 is demodulated. As shown in FIG. Is output or a signal having a DC component causes sag, and there is a problem that a good reproduction video signal cannot be obtained due to a change in hue in a part of the reproduction video signal. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to accurately perform synchronous separation of a reproduced video signal, perform normal operation of a clamp circuit, and reduce sag. It is an object of the present invention to obtain a video signal recording / reproducing apparatus which can obtain a good reproduced video signal.

[0016]

According to the present invention, there is provided a video signal recording / reproducing apparatus comprising: a PCM area signal generator for generating a control signal indicating a PCM audio signal area in a reproduction signal during reproduction; And a switch circuit for switching between the reproduction signal and the output of the delay element in accordance with the PCM area signal output from the PCM area signal generator. The output of the switch circuit is FM demodulated. It is something to do.

Further, the video signal recording / reproducing apparatus according to the present invention provides a PCM area signal generator for generating a control signal indicating a PCM audio signal area in a reproduction signal during reproduction, and delays the reproduction signal for a predetermined horizontal scanning period. A delay element is provided, and a switch circuit for switching between the reproduced signal and the output of the delay element is provided according to a PCM area signal output from the PCM area signal generator, so that the output of the switch circuit is FM demodulated. It was done.

A video signal recording / reproducing apparatus according to the present invention comprises a PCM area signal generator for generating a control signal indicating a PCM audio signal area in a reproduced signal during reproduction, and an FM signal obtained by FM-modulating a signal of a constant frequency. And an FM signal generator for generating the reproduction signal and the FM signal according to the PCM area signal output from the PCM area signal generator.
A switch circuit for switching the output of the signal generator is provided,
The output of the switch circuit is FM-demodulated.

Further, the video signal recording / reproducing apparatus according to the present invention comprises a PCM area signal generator for generating a control signal indicating a PCM audio signal area in the reproduction signal during reproduction, and a reproduction signal reproduced from each head. A delay circuit for delaying a predetermined period by τ, and a switch circuit for switching a reproduction signal from each head and an output of each of the delay elements according to a PCM area signal which is an output of the PCM area signal generator, A head switching circuit for selecting and switching the output of each switch circuit is provided, and the output of the head switching circuit is FM-demodulated.

[0020]

The video signal recording / reproducing apparatus according to the present invention comprises a PC
A switch circuit is provided for switching between a reproduction signal and a signal obtained by delaying the reproduction signal by a predetermined period τ based on a PCM area signal indicating the M audio signal area, and the output of the switch circuit is FM-demodulated. Replacing the signal in the audio signal area with the reproduced video signal of the previous field, accurately separating and synchronizing the reproduced video signal, the operation of the clamp circuit can be performed normally, the reproduced video signal does not break down, and a good reproduced image is obtained. Can be obtained. In addition, clamping can be applied even in the PCM audio signal area, and sag can be reduced.

Further, the video signal recording / reproducing apparatus according to the present invention is provided with a switch circuit for switching between a reproduced signal and a signal obtained by delaying the reproduced signal by a predetermined horizontal scanning period based on a PCM area signal indicating a PCM audio signal area. Since the output of the switch circuit is FM-demodulated, the signal in the PCM audio signal area in the reproduced video signal is replaced with a video signal obtained by repeating the data of the last line of the previous field, and the synchronous separation of the reproduced video signal is accurately performed. The operation of the circuit can be performed normally, the reproduced video signal does not break down,
A good reproduced image can be obtained. In addition, clamping can be applied even in the PCM audio signal area, and sag can be reduced.

In the video signal recording / reproducing apparatus according to the present invention, a switch circuit capable of switching based on a PCM area signal indicating a PCM audio signal area switches between a reproduced signal and an FM signal obtained by FM-modulating a signal of a constant frequency. Since the signal in the PCM audio signal area in the reproduced video signal after the output of the switch circuit is FM-demodulated is converted into a signal of a constant frequency, the synchronous separation of the reproduced video signal is accurately performed, and the operation of the clamp circuit is normally performed. As a result, the reproduced video signal is not broken and a good reproduced image can be obtained. Further, since the signal switched in the PCM audio signal area is not a signal having only a DC level, sag can be reduced.

Further, the video signal recording / reproducing apparatus according to the present invention provides a reproduction signal reproduced from each head and a signal obtained by delaying each reproduction signal by τ for a predetermined period based on a PCM area signal indicating a PCM audio signal area. Are switched by a switch circuit, and the outputs of the respective switch circuits are selected and switched by a head switching circuit to form one reproduction signal, and the output of the head switching circuit is FM-demodulated. The signal is replaced with the reproduced video signal of the previous field, the sync separation of the reproduced video signal is accurately performed, and the operation of the clamp circuit can be performed normally, so that the reproduced video signal is not broken and a good reproduced image can be obtained. . In addition, clamping can be applied even in the PCM audio signal area, and sag can be reduced.

[0024]

[Embodiment 1] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the VTR according to the first embodiment. In FIG. 1, recording systems 1 to 13
Since the reproducing systems 16 to 26 are exactly the same as those of the above-mentioned conventional apparatus, detailed description will be omitted.

Reference numeral 28 denotes a PCM decoder which detects a PCM audio signal of one field period inserted in a vertical blanking period of a reproduction signal, and performs error correction, deshuffling processing, error correction processing, etc., and converts the original audio signal. Restore and output. 29 is a PCM area signal generator for generating a PCM area signal indicating the PCM audio signal area of the reproduction signal in the PCM decoder 28, and 30 is a delay period τ
Is a switch circuit which can be switched by the PCM area signal output from the PCM area signal generator 29.

Next, the operation will be described. At the time of recording, the input video signal is A / D-converted by the A / D converter 1, and the recording signal processing circuit 3 converts the blanking data based on the sync separation output from the first sync separation circuit 2. Recording signal processing such as insertion is performed. The recording signal processing circuit 3 also generates and outputs a timing pulse for inserting a PCM audio signal into an FM video signal. The output of the recording signal processing circuit 3 is converted from a digital signal into an analog signal by a D / A converter 4 and sent to a pre-emphasis circuit 5. The pre-emphasis circuit 5 emphasizes the high frequency component of the video signal and outputs it to the FM modulator 6. The FM modulator 6 performs FM modulation on the video signal.
On the other hand, the audio signal is input to the PCM encoder 7 and subjected to shuffling processing, addition of an error correction code and the like, and then, based on the timing pulse output from the recording signal processing circuit 3, converts the digital audio signal for one field period into the above-mentioned signal. F
In order to insert the FM video signal, which is the output of the M modulator 6, into the vertical blanking period, a time axis compression process is performed, digitally modulated, and output.

Thereafter, the PCM audio signal output from the PCM encoder 7 in the one-field period is FM
The modulated video signal is inserted into the vertical blanking period at the timing shown in FIG.
1 is output. A timing pulse output from the recording signal processing circuit 3 is sent to the switches 8 and 9, and the FM video signal and the PCM audio signal are switched and added by the adder 10 to generate a recording signal. Then, the recording amplifier 11 records the FM video signal and the PCM as the recording signals.
The audio signal is amplified and recorded on the magnetic tape 13 by the rotary heads 12a and 12b. At this time, the magnetic tape 13 is strongly wound around the rotary drum 14 by 180 ° as shown in FIG. 18, and even if the recording current always flows through the rotary heads 12a and 12b, the magnetic tape 13 is not recorded on the magnetic tape 13. This is only during the period when the rotating head is in contact with the magnetic tape 13. Therefore, the recording pattern on the magnetic tape 13 is recorded separately in two areas a and b as shown in FIG. 20, and the recording signal of one field is recorded on one track. In the drawing, a indicates a track recorded by the rotary head 12a, and b indicates a track recorded by the rotary head 12b. The PCM audio signal is F
Since time-division multiplexing and recording are performed during the vertical blanking period of the M video signal, the portion where the PCM audio signal is recorded is a hatched portion. The operation at the time of recording so far is the same as in the above-described conventional example.

Next, the operation at the time of reproduction will be described. The reproduced FM video signal reproduced from the rotary heads 12a and 12b and the PCM audio signal mixed at the time of recording are output to the head amplifier 1
Amplified at 6a, 16b. Then, the reproduced signals, which are the outputs of the head amplifiers 16a and 16b,
In the head switching circuit 17, as shown in FIG. 21, a reproduction signal from the rotating head in contact with the magnetic tape 13 is selected and switched based on the head switching signal, and one reproduction signal (FIG. 21C) is generated. Become. The playback signal from the head switching circuit 17 is sent to the playback equalizer 18 and to the PCM decoder 28. The PCM decoder 28 detects the PCM audio signal of one field period inserted in the vertical blanking period of the reproduced signal, and performs error correction, deshuffling processing, error correction processing, and the like to restore and output the original audio signal. . On the other hand, the reproduction equalizer 18 compensates for the frequency characteristics of the reproduction FM video signal of the input reproduction signal, sends it to the limiter 19, and removes the amplitude fluctuation component of the reproduction FM video signal.

When the reproduced FM video signal and the PCM audio signal multiplexed during the vertical blanking period are FM-demodulated by the FM demodulator 20 as in the conventional example,
The reproduced video signal waveform in the PCM audio signal area is shown in FIG.
The signal is output as a signal waveform like noise as shown in FIG.

Then, the reproduction signal output from the limiter 19 is sent to the switch circuit 31 and the delay element 30,
As shown in FIG. 2B, the signal in the PCM audio signal area is switched to the reproduced FM video signal of the previous field. Here, a PCM area signal generated by a PCM area signal generator 29 in the PCM decoder 28 is sent to the switch circuit 31. Note that the PCM area signal generator 29
In the CM decoder 28, a PCM area signal indicating the PCM audio signal area is generated by detecting the end timing of the PCM audio signal area of the reproduction signal and predicting the start time of the next PCM audio signal area from the above detection result. doing.

In the PCM area signal generator 29, PC
A pulse indicating the M audio signal area and the video signal area is generated and sent to the switch circuit 31. In the switch circuit 31,
In the video signal area, the reproduced signal output from the limiter 19 is selected as shown in FIG. 3A, while in the PCM audio signal area, the output of the delay element 30 having a delay time τ as shown in FIG. Switch to From the delay element 30, P
Since the reproduced FM signal obtained by delaying the signal of the previous field of the CM audio signal area by τ is output, the signals of the PCM audio signal area are A1, A2 delayed by τ period of the previous field as shown in FIG. It becomes the reproduced FM signal of the part .

Therefore, as shown in FIG. 3C, the reproduced FM signal output from the switch circuit 31 input to the FM demodulator 20 has the PCM audio signal inserted in the PCM audio signal area. Since a reproduced FM signal obtained by delaying the signal of the previous field of the vertical blanking period by τ period is inserted, the output of the switch circuit 31 is FM-demodulated by the FM demodulator 20, and the output of the pre- When the high-frequency component emphasized by the emphasis circuit 5 is attenuated, a reproduced video signal with reduced high-frequency noise as shown in FIG. 2B is obtained. And P
Since the signal of the CM audio signal region will be replaced by the playback video signal of the previous field, the sync separator of the reproduced video signal is accurately performed, the operation of the clamp circuit 22 is to be performed normally. In addition, the synchronization signal is also added to the signal in the PCM audio signal area, so that the signal can be clamped also in the PCM audio signal area, and sag is reduced.

The reproduced video signal output from the de-emphasis circuit 21 is clamped at a predetermined DC voltage level at the leading end of the synchronizing signal in the clamp circuit 22, and is converted from an analog signal to a digital signal by the A / D converter 23. It is A / D converted and sent to the reproduction signal processing circuit 25. The second sync separation circuit 24 separates a sync signal from the reproduced video signal. The reproduction signal processing circuit 25 performs reproduction signal processing such as time axis correction and drop-out compensation on the reproduced video signal based on the sync separation output from the second sync separation circuit 24, and the digital signal is converted by the D / A converter 26. When the digital signal is converted from analog to analog and output, a good reproduced video signal can be obtained.

In the first embodiment, the delay time of the delay element 30 is set to τ corresponding to the period of the PCM audio signal area, and the PCM audio signal is multiplexed in the vertical blanking period of the recording video signal. PC in audio signal area
Although the description has been given of the case where the M audio signal is switched to the reproduced FM video signal for the τ period before the previous field and subjected to FM demodulation, the delay time of the delay element 30 is not limited to this, and the signal in the PCM audio signal area is converted to the PCM audio signal. If it is a delay time for switching to a reproduced FM video signal other than the audio signal area,
The same effects as in the above embodiment can be obtained.

Further, in the first embodiment, at the time of reproduction, FIG.
Although the case where the PCM audio signal mixed with the reproduced FM video signal shown in (a) is processed as the reproduced signal as it is has been described, for example, at the output of the limiter 19, the FM video signal and the PCM audio signal in the reproduced signal are shown in FIG. b) Even if it is configured to be separated as in
The reproduced video signal after demodulation becomes noise in the PCM audio signal area as shown in FIG. 26 (c) and FIG.
Therefore, similar to the above embodiment, based on the PCM area signal output from the PCM area signal generator 29, reproducing the Oite video signal area to the switch circuit 3 1 FM video signal (FIG. 4 (b)) a, PCM audio In the signal area, the reproduction F
By selecting and switching the output (FIG. 4C) obtained by delaying the M video signal by τ by the delay element 30, the same effect as in the above embodiment can be obtained.

In the first embodiment, the PCM area signal generator 29 detects the end timing of the PCM audio signal area in the reproduced signal, and predicts the start time of the next PCM audio signal area from the detection result. P depending on the configuration
The case where the CM area signal is generated has been described.
The method of generating the M-region signal is not limited to this, and may be generated, for example, from the timing of the head switching signal .

In the first embodiment, the PCM audio signal is switched by the switch 8 during the vertical blanking period of the FM video signal.
9, the switching recording is described. However, the present invention is not limited to this. For example, the PCM audio signal may be divided and switched and inserted in the horizontal blanking period. Also, in a VTR that records and reproduces a video signal of one field by dividing it into a plurality of segments as shown in FIG. 5 (FIG. 5 shows a case of two-segment division), each segment blanking period and vertical blanking In the case where a PCM audio signal of one field is divided and inserted during recording and recorded and reproduced, the reproduction F
Identifying a region of the PCM audio signal mixed with the M video signal and generating a control signal indicating the PCM audio signal region;
As long as the switch circuit 31 is switched based on the control signal, a recording format in which the PCM audio signal is recorded during the segment blanking period may be used, and the same effects as those of the first embodiment can be obtained.

In the first embodiment, the magnetic tape is
Although the case where recording is performed on one field and one track by 0 ° winding has been described, the winding angle and the recording format are not limited to this. For example, as in the case of the multi-channel multi-segment recording method, one field is composed of a plurality of tracks. It may be recorded.

Embodiment 2 FIG. In the first embodiment, FM
A case has been described in which the modulated video signal is applied to a magnetic recording / reproducing apparatus (VTR) that records and reproduces the modulated video signal on a magnetic tape by means of a rotary head. Any device may be used as long as it reproduces the video signal. For example, as in the second embodiment shown in FIG. Other video signal recording / reproducing devices, such as a magneto-optical disk and the like, have the same effect as the above embodiment.

Embodiment 3 FIG. In the above embodiment, and τ corresponding to the delay time of the delay element 30 to the PCM audio signal area period, PCM audio playback FM video signal of τ period previous to the previous field blanking period with a PC M sound voice signal Although the case where the FM demodulation is performed by switching in the signal area has been described, as in the third embodiment shown in FIG.
H), the signal in the PCM audio signal area is repeated by the switch circuit 31 to repeat the data of the last line of the previous field in the blanking period in which the PCM audio signal is inserted. Play F
The same effect as in the above-described embodiment can be obtained even when the configuration is changed to the M video signal and FM demodulation is performed.

At this time, the switch circuit 31 selects the reproduced FM video signal output from the limiter 19 in the video signal area based on the PCM area signal from the PCM area signal generator 29 and sends it to the FM demodulator 20 as it is. , On the other hand, P
In the CM audio signal area, switching is performed so as to select the output of the delay element 32 having a delay time of 1H. From the delay element 32, P
The reproduced FM video signal, which is the data of the last line of the previous field of the CM audio signal area, is repeatedly output.
The signal in the audio signal area is a signal in which a reproduced FM video signal, which is data of the last line of the previous field, is repeated.
The output of the switch circuit 31 is output to the FM demodulator 20.
When the high frequency component emphasized by the pre-emphasis circuit 5 in the recording circuit is attenuated by the de-emphasis circuit 21, a reproduced video signal with reduced high-frequency noise is obtained, and the PCM audio signal The signal of the area is repeatedly replaced with the reproduced video signal of the last line of the previous field. Therefore, the sync separation of the reproduced video signal can be accurately performed, and the operation of the clamp circuit 22 is performed normally. In addition, the synchronization signal is also added to the signal in the PCM audio signal area, so that the signal can be clamped also in the PCM audio signal area, and sag is reduced.

In the third embodiment, the delay time of the delay element 32 is set to 1H, the PCM audio signal is multiplexed in the vertical blanking period of the recording video signal, and the PCM audio signal in the PCM audio signal area is reproduced at the time of reproduction. The case where the reproduced FM video signal of the last line of the field is repeatedly replaced and subjected to FM demodulation has been described. However, the delay time of the delay element 32 is not limited to this, and may be a delay time of 2H or more. If the configuration is such that the signal is repeatedly replaced with the reproduced FM video signal of the previous field other than the PCM audio signal area, the same effect as in the above embodiment can be obtained.

Also, in the third embodiment, at the time of reproduction, FIG.
Although the case where the PCM audio signal mixed with the reproduced FM video signal shown in (a) is processed as the reproduced signal as it is has been described, for example, at the output of the limiter 19, the FM video signal and the PCM audio signal in the reproduced signal are shown in FIG. b) Even if it is configured to be separated as in
The reproduced video signal after demodulation becomes noise in the PCM audio signal area as shown in FIG. 26 (c) and FIG.
Therefore, similar to the above embodiment, based on the PCM area signal output from the PCM area signal generator 29, a reproduced FM video signal in Oite video signal area to the switch circuit 3 1, the reproduced FM video in PCM audio signal area The same effect as in the above embodiment can be achieved by selecting and switching the output obtained by delaying the signal by 1H by the delay element 32.

In the third embodiment, the PCM area signal generator 29 detects the end timing of the PCM audio signal area in the reproduced signal, and predicts the start time of the next PCM audio signal area from the detection result. P depending on the configuration
The case where the CM area signal is generated has been described.
The method of generating the M-region signal is not limited to this, and may be generated, for example, from the timing of the head switching signal .

Further, in the third embodiment, the switch 8 is used to switch the PCM audio signal during the vertical blanking period of the FM video signal.
9, the switching recording is described. However, the present invention is not limited to this. For example, the PCM audio signal may be divided and switched and inserted in the horizontal blanking period. Also, in a VTR that records and reproduces a video signal of one field by dividing it into a plurality of segments as shown in FIG. 5 (FIG. 5 shows a case of two-segment division), each segment blanking period and vertical blanking In the case where a PCM audio signal of one field is divided and inserted during recording and recorded and reproduced, the reproduction F
Identifying a region of the PCM audio signal mixed with the M video signal and generating a control signal indicating the PCM audio signal region;
If the switch circuit 31 is switched based on the control signal, a recording format in which a PCM audio signal is recorded during the segment blanking period may be used, and the same effects as those of the above embodiment can be obtained.

In the third embodiment, the magnetic tape is
Although the case where recording is performed on one field and one track by 0 ° winding has been described, the winding angle and the recording format are not limited to this. For example, as in the case of the multi-channel multi-segment recording method, one field is composed of a plurality of tracks. It may be recorded.

Embodiment 4 FIG. In the third embodiment, the FM
A case has been described in which the modulated video signal is applied to a magnetic recording / reproducing apparatus (VTR) that records and reproduces the modulated video signal on a magnetic tape by means of a rotary head. Any device may be used as long as it reproduces the image signal. For example, as in a fourth embodiment shown in FIG. Other video signal recording / reproducing devices, such as a magneto-optical disk and the like, have the same effect as the above embodiment.

Embodiment 5 FIG. FIG. 9 shows a fifth embodiment of the present invention.
In the figure, a recording system 1 to 13 and a reproduction system 16 to 26 are exactly the same as those of the above-mentioned conventional apparatus, and a detailed description thereof will be omitted.

A PCM 33 detects a PCM audio signal of one field period inserted in a vertical blanking period of a reproduced signal, and performs error correction, deshuffling processing, error correction processing and the like to restore and output an original audio signal. A decoder 34 identifies a PCM audio signal area in the reproduced signal in the PCM decoder 33 and generates a PCM area signal indicating the PCM audio signal area. A PCM area signal generator 35 superimposes on a gray level after FM demodulation, for example. and constant frequency f _p, FM signal generator FM signal becomes a signal having an amplitude B (carrier frequency that. to f _c) to output generates, 36 PCM region to be output from the PCM area signal generator 34 A switch circuit for switching a reproduction signal output from the limiter 19 and an output from the FM signal generator 35 based on the signal. A.

Next, the operation will be described. At the time of recording, the input video signal is A / D-converted by the A / D converter 1, and the recording signal processing circuit 3 converts the blanking data based on the sync separation output from the first sync separation circuit 2. Recording signal processing such as insertion is performed. The recording signal processing circuit 3 also generates and outputs a timing pulse for inserting a PCM audio signal into an FM video signal. The output of the recording signal processing circuit 3 is converted from a digital signal into an analog signal by a D / A converter 4 and sent to a pre-emphasis circuit 5. The pre-emphasis circuit 5 emphasizes the high frequency component of the video signal and outputs it to the FM modulator 6. The FM modulator 6 performs FM modulation on the video signal.
On the other hand, the audio signal is input to the PCM encoder 7 and subjected to shuffling processing, addition of an error correction code and the like, and then, based on the timing pulse output from the recording signal processing circuit 3, converts the digital audio signal for one field period into the above-mentioned signal. F
In order to insert the FM video signal, which is the output of the M modulator 6, into the vertical blanking period, the signal is subjected to time axis compression processing, digitally modulated, and output.

Thereafter, the PCM audio signal for one field period output from the PCM encoder 7 is FM
The modulated video signal is inserted into the vertical blanking period at the timing shown in FIG.
1 is output. A timing pulse output from the recording signal processing circuit 3 is sent to the switches 8 and 9, and the FM video signal and the PCM audio signal are switched and added by the adder 10 to generate a recording signal. Then, the recording amplifier 11 records the FM video signal and the PCM as the recording signals.
The audio signal is amplified and recorded on the magnetic tape 13 by the rotary heads 12a and 12b. At this time, the magnetic tape 13 is strongly wound around the rotary drum 14 by 180 ° as shown in FIG. 18, and even if the recording current always flows through the rotary heads 12a and 12b, the magnetic tape 13 is not recorded on the magnetic tape 13. This is only during the period when the rotating head is in contact with the magnetic tape 13. Therefore, the recording pattern on the magnetic tape 13 is recorded separately in two areas a and b as shown in FIG. 20, and the recording signal of one field is recorded on one track. In the drawing, a indicates a track recorded by the rotary head 12a, and b indicates a track recorded by the rotary head 12b. The PCM audio signal is F
Since time-division multiplexing and recording are performed during the vertical blanking period of the M video signal, the portion where the PCM audio signal is recorded is a hatched portion. The operation at the time of recording so far is the same as in the above-described conventional example.

At the time of reproduction, the rotary heads 12a and 12b reproduce the reproduction FM video signal and the PCM audio signal mixed at the time of recording from the magnetic tape 13 as a reproduction signal, and amplify them by the head amplifiers 16a and 16b. A reproduction signal, which is an output of each of the head amplifiers 16a and 16b, is converted by a head switching circuit 17 based on the reproduction signal from the rotating head in contact with the magnetic tape 13 as shown in FIG. To select and switch to one reproduction signal (FIG. 21C). And
Reproduced signal from the head switching circuit 17 is fed to a PCM decoder 3 3 together and sent to the reproduction equalizer 18. In PCM decoder 3 3 detects a PCM audio signal of one field period which is inserted in a vertical blanking period of the reproduced signal, error correction, deshuffling process, to restore the subjecting original audio signal error correcting process like output . On the other hand, the reproduction equalizer 18 compensates for the frequency characteristics of the reproduction FM video signal of the input reproduction signal, sends it to the limiter 19, and removes the amplitude fluctuation component of the reproduction FM video signal.

When the reproduced FM video signal and the PCM audio signal multiplexed in the vertical blanking period are FM-demodulated by the FM demodulator 20 as in the conventional example,
The reproduced video signal waveform in the PCM audio signal area is shown in FIG.
The signal is output as a signal waveform like noise as shown in FIG.

Therefore, in the FM signal generator 35, for example, after FM demodulation, an FM modulated signal (carrier frequency is f _c ) which becomes a signal of constant frequency f _p and amplitude B superimposed on the gray level is generated and output. , This FM signal generator 35
And the reproduced signal output from the limiter 19 are represented by P
The input is switched to a switch circuit 36 which can switch the output according to a PCM area signal indicating a CM audio signal area, and the output is switched.
The reproduced video signal waveform after FM demodulation of the output of the switch circuit 36 is made to be a signal as shown in FIG.
The switch circuit 36 includes a PC in the PCM decoder 33.
The PCM area signal generated by the M area signal generator 34 is sent. The PCM area signal generator 34 detects the end timing of the PCM audio signal area of the reproduced signal in the PCM decoder 33, and predicts the start time of the next PCM audio signal area from the detection result. A PCM area signal indicating an audio signal area is generated.

In the PCM area signal generator 34, the PC
Sending the M audio signal area and generates a pulse indicating a video signal area switching circuit 36, and Save the switch circuit 36
In the video signal area period, the reproduction signal sent from the limiter 19 (FIG. 11A) is selected, and in the PCM audio signal area period, the output of the FM signal generator 35 (FIG. 11B).
Select and output. Therefore, the output of the switch circuit 36 is as shown in FIG. 11C. The output of the switch circuit 36 is sent to the FM demodulator 20 to perform FM demodulation.
The signal in the PCM audio signal area in the reproduced video signal after passing through the emphasis circuit 21 is a signal having a frequency fp and an amplitude B superimposed on a gray level as shown in FIG.

By doing so, the signal in the PCM audio signal area of the reproduced video signal demodulated by FM can be converted into a signal of constant frequency f _p and amplitude B superimposed on the gray level, so that the video signal can be separated in synchronization. Can be performed accurately. Further, since the signal switched in the PCM audio signal area is not a signal having only a DC level, sag can be reduced.

The reproduced signal output from the switch circuit 36 is FM-demodulated by the FM demodulator 20 and the de-emphasis circuit 21 outputs the pre-emphasis circuit 5 in the recording circuit.
When the high-frequency component emphasized in step (1) is attenuated, a reproduced video signal in which high-frequency noise is reduced as shown in FIG. 10 is obtained. Then, the reproduced video signal output from the de-emphasis circuit 21 is input to the clamp circuit 22, where the leading end of the synchronizing signal of the reproduced video signal is clamped to a predetermined DC voltage level. Thereafter, the reproduced video signal is output to the A / D converter 2
At 3, the analog signal is A / D converted to a digital signal and sent to the reproduction signal processing circuit 25. Further, the second sync separation circuit 24 separates a sync signal from the reproduced video signal. The reproduction signal processing circuit 25 performs reproduction signal processing such as time axis correction and dropout compensation on the reproduced video signal based on the sync separation output from the second sync separation circuit 24, and outputs the output to a D / A converter. By performing D / A conversion at 26, a good reproduced video signal is obtained.

In the fifth embodiment, the FM signal generator 3
In 5, constant frequency f _p superimposed on the gray level after FM demodulation, but FM signals become signals of an amplitude B (carrier frequency f _c) has been described a case where outputting generate, is not limited thereto, If an FM modulation signal other than a constant DC level signal and having a certain frequency that reduces sag is generated between the pedestal level and the white level after the FM demodulation, the same as in the above-described embodiment. It works.

In the fifth embodiment, the end timing of the PCM audio signal area in the reproduced signal is detected by the PCM area signal generator 34, and the start time of the next PCM audio signal area is predicted from the detection result. P depending on the configuration
The case where the CM area signal is generated has been described.
The method of generating the M-region signal is not limited to this, and may be generated, for example, from the timing of the head switching signal .

In the fifth embodiment, the reproduction F
Although the case where the PCM audio signal mixed with the M video signal is FM-demodulated and processed as a reproduction signal as described above,
For example, even when the output of the limiter 19 is configured so that the FM video signal and the PCM audio signal in the reproduction signal are separated as shown in FIG. 12B, the reproduction video signal after the FM demodulation is the same as that in FIG. As shown in FIG. 25C and FIG. 25, noise occurs in the PCM audio signal area. Therefore, similar to the above embodiment, based on the PCM area signal output from the PCM area signal generator 34, reproducing the Oite video signal area to the switch circuit 3 6 FM video signal (FIG. 12 (b)) a, PCM audio In the signal area, the above F
By selecting and switching the output of the M signal generator (FIG. 12C), the same effect as in the fifth embodiment can be obtained.

In the fifth embodiment, the PCM audio signal is supplied to the switch 8 during the vertical blanking period of the FM video signal.
9, the switching recording is described. However, the present invention is not limited to this. For example, the PCM audio signal may be divided and switched and inserted in the horizontal blanking period. Also, in a VTR that records and reproduces a video signal of one field by dividing it into a plurality of segments as shown in FIG. 5 (FIG. 5 shows a case of two-segment division), each segment blanking period and vertical blanking In the case where a PCM audio signal of one field is divided and inserted during recording and recorded and reproduced, the reproduction F
Identifying a region of the PCM audio signal mixed with the M video signal and generating a control signal indicating the PCM audio signal region;
As long as the switch circuit is switched based on the control signal, a recording format in which the PCM audio signal is recorded during the segment blanking period may be used, and the same effect as that of the fifth embodiment can be obtained.

In the fifth embodiment, the magnetic tape is 18
Although the case where recording is performed on one field and one track by 0 ° winding has been described, the winding angle and the recording format are not limited to this. For example, as in the case of the multi-channel multi-segment recording method, one field is composed of a plurality of tracks. It may be recorded.

Embodiment 6 FIG. In the fifth embodiment, the FM
A case has been described in which the modulated video signal is applied to a magnetic recording / reproducing apparatus (VTR) that records and reproduces the modulated video signal on a magnetic tape by means of a rotary head. Any device can be used as long as it reproduces the image signal. For example, as in the sixth embodiment shown in FIG. Other video signal recording / reproducing devices, such as a magneto-optical disk and the like, have the same effect as the above embodiment.

Embodiment 7 FIG. FIG. 14 is a block diagram of a VTR according to the seventh embodiment of the present invention. In the figure, the recording systems 1 to 13 and the reproduction systems 16 to 26 are completely the same as those of the above-mentioned conventional apparatus, so that detailed description will be omitted.

A PCM 37 detects a PCM audio signal of one field period inserted in a vertical blanking period of a reproduced signal, and performs error correction, deshuffling processing, error correction processing, and the like to restore and output an original audio signal. A decoder 38 accurately detects a PCM audio signal area of the reproduced signal in the PCM decoder 37 and generates a PCM area signal indicating the PCM audio signal area. 39 denotes an output from the head amplifier 16a. Delay elements I and 40 for delaying a certain reproduction signal by a delay period τ are delay elements II and 41 and 42 for delaying a reproduction signal output from the head amplifier 16b by τ, and outputs from the PCM area signal generator 38. This is a switch circuit that can perform switching control based on a certain PCM area signal.

Next, the operation will be described. At the time of recording, the input video signal is A / D-converted by the A / D converter 1, and the recording signal processing circuit 3 converts the blanking data based on the sync separation output from the first sync separation circuit 2. Processing such as insertion into a recording video signal is performed.
The recording signal processing circuit 3 converts the FM video signal into a PC signal.
A timing pulse for inserting the M audio signal is also generated and output. The output of the recording signal processing circuit 3 is D
The digital signal is converted into an analog signal by the / A converter 4 and sent to the pre-emphasis circuit 5. Puri
The emphasis circuit 5 emphasizes the high frequency component of the video signal and outputs it to the FM modulator 6. The FM modulator 6 performs FM modulation on the video signal. On the other hand, the audio signal is input to the PCM encoder 7 and subjected to shuffling processing, addition of an error correction code and the like, and then, based on the timing pulse output from the recording signal processing circuit 3, converts the digital audio signal for one field period into the above-mentioned signal. In order to insert into the vertical blanking period of the FM video signal which is the output of the FM modulator 6, it is subjected to time axis compression processing, digitally modulated and output.

Thereafter, the PCM audio signal for one field period output from the PCM encoder 7 is FM
The modulated video signal is inserted into the vertical blanking period at the timing shown in FIG.
1 is output. A timing pulse output from the recording signal processing circuit 3 is sent to the switches 8 and 9, and the FM video signal and the PCM audio signal are switched and added by the adder 10 to generate a recording signal. Then, the recording amplifier 11 records the FM video signal and the PCM as the recording signals.
The audio signal is amplified and recorded on the magnetic tape 13 by the rotary heads 12a and 12b. At this time, the magnetic tape 13 is strongly wound around the rotary drum 14 by 180 ° as shown in FIG. 18 , and even if the recording current always flows through the rotary heads 12a and 12b, the magnetic tape 13 is not recorded on the magnetic tape 13. This is only during the period when the rotating head is in contact with the magnetic tape 13. Therefore, the recording pattern on the magnetic tape 13 is recorded separately in two areas a and b as shown in FIG. 20 , and the recording signal of one field is recorded on one track. In the drawing, a indicates a track recorded by the rotary head 12a, and b indicates a track recorded by the rotary head 12b. The PCM audio signal is F
Since time-division multiplexing and recording are performed during the vertical blanking period of the M video signal, the portion where the PCM audio signal is recorded is a hatched portion. The operation at the time of recording so far is the same as in the above-described conventional example.

At the time of reproduction, the rotary heads 12a and 12b reproduce the reproduction FM video signal and the PCM audio signal mixed at the time of recording from the magnetic tape 13, respectively.
a. Amplify at 16b. Then, the reproduced signals from the rotary head amplified by the head amplifiers 16a and 16b, respectively, are switched by the switch circuits 41 and 42 and the delay element 39,
40, and also to the PCM decoder 37. In the PCM decoder 37, the head amplifier 16
PC of one field period inserted in the vertical blanking period in the reproduction signal sent from each of a and 16b
The M audio signal is detected, and the original audio signal is restored and output by performing shuffling processing, error correction processing, and the like.

When the reproduced FM video signal and the PCM audio signal multiplexed in the vertical blanking period are FM-demodulated by the FM demodulator 20 as in the conventional example,
The reproduced video signal waveform in the PCM audio signal area is shown in FIG.
The signal is output as a signal waveform like noise as shown in FIG.

Therefore, the reproduced signal of FIG. 15 (a) output from the head amplifier 16a is input to the switch circuit 41 and the delay element I39, and the reproduced signal of FIG. 15 (b) from the head amplifier 16b is converted to the switch circuit. 42 and the delay element II40. And the switch circuit 4
1 and 42, the signal in the PCM audio signal area in the reproduced video signal after the FM demodulation is converted into the signal shown in FIG.
As described above, the signal is switched to the signal of the line preceding by the PCM audio signal area period of the previous field. The PCM area signal generated by the PCM area signal generator 38 in the PCM decoder 37 is sent to the switch circuits 41 and 42. The PCM area signal generator 38 detects the end timing of the PCM audio signal area of the reproduction signal in the PCM decoder 37, and predicts the start time of the next PCM audio signal area from the detection result. A PCM area signal indicating a PCM audio signal area is generated.

In the PCM area signal generator 38, the PC
A pulse indicating the M audio signal area and the video signal area is generated and sent to the switch circuits 41 and 42. The switch circuit 41 selects the reproduction signal (FIG. 15A) of the rotary head 12a, which is the output of the head amplifier 16a, in the video signal area, while the head amplifier 1 in the PCM audio signal area.
The reproduced signal of the rotary head 16b, which is the output of the rotary head 16b (FIG. 15)
(B)) is switched to select the output of the delay element II40 delayed by τ period as shown in FIG. 15 (d). Then, the switch circuit 42 selects the reproduction signal (FIG. 15B) of the rotary head 12b, which is the output of the head amplifier 16b, in the video signal area, and the rotation signal, which is the output of the head amplifier 16a, in the PCM audio signal area. Head 16a
15 (a) is switched to select the output of the delay element I39 delayed by τ period as shown in FIG. 15 (c). The delay element I 39 outputs a reproduced FM video signal obtained by delaying the signal of the previous field of the PCM audio signal area in the reproduced signal from the head amplifier 16 a by τ, and the delay element II 40 outputs the reproduced FM video signal from the head amplifier 16 b. The reproduced FM video signal obtained by delaying the signal of the previous field of the PCM audio signal area in the reproduced signal of by τ is output.
As shown in (e), the output from the switch circuit 42 is as shown in FIG. 15 (f). Therefore, the signals in the PCM audio signal area in the reproduced signals from the respective heads are located before the PCM audio signal area. It becomes a reproduced FM video signal for the τ period of the field.

Therefore, the respective outputs of the switch circuits 41 and 42 are input to the head switching circuit 17,
Assuming that a reproduction signal from the rotary head in contact with the magnetic tape 13 is selected and switched based on the head switching signal and one reproduction signal is output, the output is as shown in FIG. The reproduced signal output from the head switching circuit 17 is sent to a reproducing equalizer 18 where the frequency characteristic of the reproduced FM video signal is compensated and sent to a limiter 19 where the amplitude of the reproduced FM video signal is amplified. Remove the fluctuation component. The output of the limiter 19 is then input to an FM demodulator 20 where it is FM-demodulated, and the de-emphasis circuit 21 attenuates the high-frequency component emphasized by the pre-emphasis circuit 5 in the recording circuit. A reproduced video signal with reduced high-frequency noise as shown in b) is obtained. Then, since the signal in the PCM audio signal area is replaced with the reproduced video signal of the previous field, the synchronous separation of the reproduced video signal can be accurately performed, and the operation of the clamp circuit 22 is performed normally. In addition, since the synchronization signal is also added to the signal in the PCM audio signal area, clamping can be applied also in the PCM audio signal area, and sag is reduced.

The reproduced video signal output from the de-emphasis circuit 21 is clamped to a predetermined DC voltage level at the leading end of the synchronizing signal by the clamp circuit 22.
A / D converter 23 converts analog signals to digital signals.
/ D converted and sent to the reproduction signal processing circuit 25. The second sync separation circuit 24 separates a sync signal from the reproduced video signal. The reproduction signal processing circuit 25 performs reproduction signal processing such as time axis correction and drop-out compensation on the reproduced video signal based on the sync separation output from the second sync separation circuit 24, and the digital signal is converted by the D / A converter 26. When the digital signal is converted from analog to analog and output, a good reproduced video signal can be obtained.

In the seventh embodiment, the delay time of the delay elements 39 and 40 is set to τ corresponding to the PCM audio signal area period, and the reproduced FM video signal before the τ period of the previous field of the PCM audio signal area is output. Although the case where the switching is performed in the PCM audio signal area has been described, the delay time of the delay elements 39 and 40 is not limited to this.
If the delay time is such that the signal in the PCM audio signal area is switched to a reproduced FM video signal other than the PCM audio signal area in the previous field, the same effect as in the above embodiment can be obtained.

In the seventh embodiment, the end timing of the PCM audio signal area in the reproduction signal is detected by the PCM area signal generator 38, and the start time of the next PCM audio signal area is predicted from the detection result. P depending on the configuration
The case where the CM area signal is generated has been described.
The method of generating the M-region signal is not limited to this, and may be generated, for example, from the timing of a head switching signal.

In the seventh embodiment, the reproduction F
The case has been described where the PCM audio signal mixed with the M video signal is processed as it is as a reproduction signal by switching between the switch circuits 41 and 42. For example, at the output of the head amplifier, the FM video signal and the PCM audio signal in the reproduction signal are 16 (c) and 16 (d), even when the switch circuit is switched based on the PCM area signal by inputting to the switch circuit and the delay element, the output of the head switching circuit is as shown in FIG. As shown in (g), the same effect as in the above embodiment can be obtained.

In the seventh embodiment, the PCM audio signal is supplied to the switch 8 during the vertical blanking period of the FM video signal.
9, the switching recording is described. However, the present invention is not limited to this. For example, the PCM audio signal may be divided and switched and inserted in the horizontal blanking period. Also, in a VTR that records and reproduces a video signal of one field by dividing it into a plurality of segments as shown in FIG. 5 (FIG. 5 shows a case of two-segment division), each segment blanking period and vertical blanking In the case where a PCM audio signal of one field is divided and inserted during recording and recorded and reproduced, the reproduction F
Identifying a region of the PCM audio signal mixed with the M video signal and generating a control signal indicating the PCM audio signal region;
As long as the switch circuit is switched based on the control signal, a recording format in which the PCM audio signal is recorded during the segment blanking period may be used, and the same effects as in the above embodiment can be obtained.

In the seventh embodiment, the magnetic tape is
Although the case where recording is performed on one field and one track by 0 ° winding has been described, the winding angle and the recording format are not limited to this. For example, as in the case of the multi-channel multi-segment recording method, one field is composed of a plurality of tracks. It may be recorded.

[0079]

As described above, according to the present invention, PCM
The audio signal is multiplexed in a time-division manner during the blanking period of the FM video signal and recorded and reproduced. Based on the PCM area signal indicating the PCM audio signal area at the time of reproduction, the reproduced signal before FM demodulation and this reproduced signal are fixed for τ. A switch circuit for switching a signal delayed by only one time is provided, and the signal of the PCM audio signal area in the reproduced video signal after the FM output of the switch circuit is demodulated is converted to a period before the blanking period in which the PCM audio signal is inserted. Since it is configured to replace the playback video signal, the sync separation of the playback video signal is performed accurately,
Clamping can also be performed in the PCM audio signal area, sag can be reduced, and a good reproduced video signal can be obtained.

As described above, according to the present invention, P
The CM audio signal is multiplexed and recorded and reproduced in a time-division manner during the blanking period of the FM video signal. Based on the PCM area signal indicating the PCM audio signal area at the time of reproduction, the reproduced signal before FM demodulation and this reproduced signal are horizontally reproduced. A switch circuit for switching the signal delayed in the scanning period is provided, and the signal in the PCM audio signal area in the reproduced video signal after FM demodulation of the switch circuit output is converted to a signal before the blanking period in which the PCM audio signal is inserted. Since the playback video signal of the last line of the period is configured to be replaced with a repeated signal, the synchronization of the playback video signal can be accurately performed, the clamp can be applied even in the PCM audio signal area, and sag can be reduced. Thus, there is an effect that a good reproduced video signal can be obtained.

As described above, according to the present invention, P
The CM audio signal is multiplexed in a time-division manner during the blanking period of the FM video signal, recorded and reproduced. Based on the PCM area signal indicating the PCM audio signal area during reproduction, the reproduction signal and the FM signal obtained by FM-modulating the signal of a fixed frequency are converted A switching circuit is provided for switching, and a signal in a PCM audio signal area in a reproduced video signal after FM demodulation of the output of the switching circuit becomes a signal of a constant frequency superimposed on a video signal level from a pedestal level to a white level. With such a configuration, it is possible to accurately perform synchronous separation of the reproduced video signal, perform the operation of the clamp circuit normally, reduce sag, and obtain a good reproduced video signal.

As described above, according to the present invention, P
The CM audio signal is recorded and reproduced in a time-division multiplexed manner during the blanking period of the FM video signal, and based on the PCM area signal indicating the PCM audio signal area during reproduction, each reproduced signal from each rotary head and each reproduced signal are reproduced. Is switched by a switch circuit, and the output of each switch circuit is selected and switched by a head switching circuit, and the output of the head switching circuit is
Since the signal in the PCM audio signal area in the reproduced video signal after the M demodulation is replaced with the reproduced video signal in the period before the blanking period in which the PCM audio signal is inserted, the synchronization separation of the reproduced video signal is performed. Do exactly, P
Clamping can also be performed in the CM audio signal area, sag can be reduced, and there is an effect that a good reproduced video signal can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a magnetic recording / reproducing apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a waveform chart showing an example of an output waveform of a reproduced video signal after FM demodulation according to the embodiment of the present invention.

FIG. 3 is a waveform chart for explaining operations of a PCM area signal generator, a delay element, and a switch circuit according to the first embodiment of the present invention.

FIG. 4 is a waveform diagram for explaining operations of a delay element and a switch circuit when an FM video signal and a PCM audio signal of a reproduction signal are separated and processed in the first embodiment of the present invention.

FIG. 5 is a diagram showing an example of a case where a PCM audio signal is multiplexed in a time-division manner in each segment blanking period of an FM video signal in a VTR of two-segment recording.

FIG. 6 is a block diagram showing a video signal recording / reproducing apparatus according to Embodiment 2 of the present invention.

FIG. 7 is a block diagram showing a magnetic recording / reproducing apparatus according to Embodiment 3 of the present invention.

FIG. 8 is a block diagram showing a video signal recording / reproducing apparatus according to Embodiment 4 of the present invention.

FIG. 9 is a block diagram showing a magnetic recording / reproducing apparatus according to Embodiment 5 of the present invention.

FIG. 10 is a waveform chart showing an example of an output waveform of a reproduced video signal in Embodiment 5 of the present invention.

FIG. 11 is a waveform chart for explaining operations of a PCM area signal generator, an FM signal generator, and a switch circuit in Embodiment 5 of the present invention.

FIG. 12 is a waveform diagram for explaining operations of an FM signal generator and a switch circuit when separating and processing an FM video signal and a PCM audio signal of a reproduction signal in a fifth embodiment of the present invention.

FIG. 13 is a block diagram showing a video signal recording / reproducing apparatus according to Embodiment 6 of the present invention.

FIG. 14 is a block diagram showing a magnetic recording / reproducing apparatus according to Embodiment 7 of the present invention.

FIG. 15 is a waveform chart for explaining the operation of a PCM area signal generator, each delay element, and each switch circuit in Embodiment 7 of the present invention.

FIG. 16 is a waveform diagram for explaining the operation of each delay element and switch circuit when separating and processing an FM video signal and a PCM audio signal of a reproduction signal in the seventh embodiment of the present invention.

FIG. 17 is a block diagram illustrating an example of a conventional magnetic recording / reproducing apparatus.

FIG. 18 is a view of the rotating drum as viewed from above.

FIG. 19 is a diagram illustrating an example of a case where a PCM audio signal is multiplexed in a time-division manner during a blanking period of an FM video signal.

FIG. 20 is a diagram showing a recording pattern on a magnetic tape.

FIG. 21 is a diagram for explaining the operation of the head switching circuit.

FIG. 22 is a diagram for explaining operations of a reproduction equalizer and a limiter.

FIG. 23 is a characteristic diagram showing an example of a frequency characteristic of a reproduction equalizer.

FIG. 24 is a characteristic diagram showing an FM video signal band and a PCM audio signal band during reproduction.

FIG. 25 is a waveform diagram showing an output waveform of a reproduced video signal after FM demodulation in a conventional magnetic recording / reproducing apparatus.

FIG. 26 shows a conventional magnetic recording / reproducing apparatus which separates and processes an FM video signal and a PCM audio signal of a reproduction signal.
FIG. 7 is a waveform diagram showing an output waveform of a reproduced video signal after FM demodulation.

[Explanation of symbols]

 29, 34, 38 PCM area signal generator 30, 32 Delay element 31, 36, 41, 42 Switch circuit 35 FM signal generator 39 Delay element I 40 Delay element II 17 Head switching circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-91471 (JP, A) JP-A-5-7357 (JP, A) JP-A-4-310080 (JP, A) JP-A-4-191 212583 (JP, A) JP-A-1-296783 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/91-5/956 G11B 20/12 103

Claims (3)

(57) [Claims] 1. A video signal recording / reproducing apparatus for FM-modulating a video signal and time-divisionally multiplexing a digital audio signal in a blanking period of the FM-modulated recording video signal for recording / reproduction. Area signal generating means for determining the area of the digital audio signal in the above, and generating a control signal indicating the area of the digital audio signal; delay means for delaying the reproduction signal for a predetermined period; and an output signal of the area signal generating means. A video signal recording / reproducing apparatus, comprising: a switching means for switching between the reproduced signal and an output of the delay means. 2. A video signal recording / reproducing apparatus which FM-modulates a video signal and multiplexes a digital audio signal in a time-division multiplex manner during a blanking period of the FM-modulated recording video signal for recording / reproduction. The delay time of the delay means for delaying the recording signal is a predetermined horizontal scanning period in the recording signal, and the output of the delay means delayed by the predetermined horizontal scanning period is switched between the reproduction signal and the delay based on the control signal indicating the area of the digital audio signal. 2. The video signal recording / reproducing apparatus according to claim 1, wherein: 3. A video signal recording / reproducing apparatus for FM-modulating a video signal and multiplexing and digitally reproducing a digital audio signal in a time-division manner during a blanking period of the FM-modulated recording video signal to reproduce and reproduce the reproduced signal. Area signal generating means for determining a region of the digital audio signal in the above, and generating a control signal indicating the area of the digital audio signal; FM signal generating means for generating a signal obtained by FM-modulating a signal of a predetermined frequency; A video signal recording / reproducing apparatus comprising: a switching unit that switches between the reproduction signal and the output of the FM signal generation unit based on an output signal of the signal generation unit.