JPH05122654A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To correctly execute the vertical synchronizing signal separation of a reproducing video signal in a video signal recording and reproducing device providing a non-signal section between a PCM sound signal and at least a signal vertically synchronizing with the sound signal in the part of the vertical blanking period of a video signal and recording/reproducing. CONSTITUTION:In the non-signal section provided between the PCM sound signal and the vertical synchronizing signal, which are inserted into the part of the vertical blanking period of the video signal, the signal of a single frequency outputted from a signal generator 40 is inserted by switching a switch 41 by a control signal outputted from a switch controlling circuit 43 based on the output of a synchronization separating circuit A4 so as to be recorded A PCM sound signal section in a reproducing video signal which is FM- demodulated at the time of reproducing and the non-signal section including the section inserted with the single frequency are clipped to the reproducing video signal over a black level with a PCM area signal as reference. Thus, the reproducing video signal is correctly synchronizing signal separated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing in which a video signal is FM-modulated and a PCM audio signal is inserted and recorded in a part of a vertical blanking period or a segment blanking period of the FM video signal. Equipment (hereinafter VTR
It refers to)).

[0002]

2. Description of the Related Art As one of the methods for recording a digital audio signal (PCM audio) on a VTR, there is a method of time-division multiplexing the PCM audio during the vertical blanking period of a recorded video signal. In the following, a wideband component color TV signal of one field is color signal line sequential time division multiplexed color TV
A VTR that converts into a signal (hereinafter referred to as a TCI signal) and divides into three segments for recording and reproduction will be described.

FIG. 24 shows a conceptual diagram of a signal processing system in which a component color TV signal of one field is converted into a TCI signal and then divided into three segments and recorded on three different tracks on a magnetic tape (note that the signal processing method is described below). 1H shown in the figure represents one horizontal scanning period). The input color TV signal is shown in FIG. First, two color difference signals (R-
Y) and (B-Y) signals are subjected to line-sequential processing as shown in FIG. 9B to be converted into a line-sequential color signal C of 1 channel. Thereafter, the luminance signal Y and the line-sequential color signal C are time-axis compressed, time-division multiplexed, and converted into a TCI signal as shown in FIG. Further, FIG. 3D shows the recording format of the TCI signal within the 1H period.

Then, by increasing the number of rotations of the drum, the video signal of one field is divided into three segments and recorded as shown in FIG. Therefore, the video information of one field is recorded on three tracks on the magnetic tape as shown in FIG. It should be noted that the numbers shown in the drawing indicate the tracks on which the video information of the first, second and third segments are recorded, respectively. Also, the shaded portion shown in the figure is the vertical blanking period of the recording signal, that is, the period in which PCM audio is inserted.

In the VTR adopting the segment recording method, a blanking period is provided in advance between each segment in order to absorb the skew generated in the head switching period (hereinafter, the blanking period is referred to as segment blanking). Referred to as the period).

FIG. 25 shows a recorded video signal in one field. As shown in the figure, an area for recording PCM audio data for one field period is provided in a part of the vertical bunking period. Hereinafter, this area is referred to as a PCM area.

FIG. 26 shows a block diagram of the present VTR for time-division multiplexing and recording / reproducing PCM audio in the vertical blanking period of the TCI signal.

First, the recording signal processing system will be described.
Reference numeral 1 is a magnetic tape, 2a, 2b and 2c are video signal input terminals, 3a, 3b and 3c are A / D converters for converting analog video signals into digital video signals, and 4 is a synchronization for performing synchronization separation from a luminance signal Y. Separation circuits A and 5 are recording signal processing circuits, which convert the input color TV signal into the TCI signal and add a synchronization signal based on the synchronization signal output from the synchronization separation circuit A4. The recording signal processing circuit 5 also performs signal processing and the like during the segment blanking period.
Done in. Reference numeral 6 is a D / A converter for converting a digital signal into an analog signal, and 7 is an F for performing FM modulation on the recording TCI signal.
M modulator.

Reference numeral 8 is an audio signal input terminal, 9 is an A / D converter for converting an analog audio signal into a digital audio signal,
Reference numeral 10 adds a shuffling process, an error correction code, a synchronizing signal, an ID signal, etc. to a digital voice signal,
This is a PCM encoder that performs time-axis compression so that a recorded digital audio signal for one field period is contained in the PCM area described above, performs digital modulation, and outputs.

11 and 12 are switches A and B and 32 are switch control circuits for controlling the switches A11 and B12 based on the outputs of the sync separation circuit A4, and 13 is an addition of the outputs of the switches A11 and B12. Adder circuit, 14 is a recording amplifier, 15a,
15b and 16a, 16b are rotary heads.

Next, the reproduction signal processing system will be described. 1
7a and 17b are head amplifiers, 18 is a head amplifier 17 based on a head switching signal (hereinafter referred to as HSW signal) output from a reference signal generating circuit 19 described later.
a head switching circuit for switching the outputs of a and 17b, 1
Reference numeral 9 is a reference signal generation circuit for outputting the HSW signal, which serves as a reference signal at the time of reproduction, to the head switching circuit, and 20 is a reproduction audio signal in the PCM area in the reproduction signal output from the head switching circuit 18 as digital data. It is a PCM decoder that performs conversion, digital demodulation, and conversion into a reproduced digital audio signal, and then performs time-axis expansion, error detection, error correction, error correction, deshuffling processing, and the like. Further, 24 is P detected in the PCM decoder.
A PCM clip circuit 25, which will be described later, outputs a signal indicating the CM area.
It is a PCM domain signal generator for outputting to. 21 is a D for converting a reproduced digital audio signal into a reproduced analog audio signal
An A / A converter 22 is an output terminal for an audio signal.

Reference numeral 23 is an FM demodulator for FM demodulating the reproduction signal output from the head switching circuit 18. In addition,
This FM demodulator 23 adopts a pulse counting method. Reference numeral 25 is a PCM clip circuit for clipping the signal in the PCM area in the reproduced video signal output from the FM demodulator 23 based on the signal output from the PCM area signal generator 24, and 26 is a clamp for the reproduced video signal. A clamp circuit 27 is a sync separation circuit B for separating a sync signal from the reproduced video signal output from the clamp circuit 26, 28 is an A / D converter for converting an analog signal into a digital signal, and 29 is a sync separation circuit B 27. Based on the output of the above, the reproduction TCI signal is subjected to time axis correction, dropout compensation, etc., and then restored and synchronized with the original luminance signal Y and two color difference signals (RY) and (BY). This is a reproduction signal processing circuit for adding signals and the like. 30a,
Reference numerals 30b and 30c are D / A converters for converting a digital signal into an analog signal, and reference numerals 31a, 31b and 31c are video signal output terminals.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit 5. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. In the recording signal processing circuit 5, the sync separation circuit A4
Is converted into a TCI signal on the basis of the output of the above and subjected to a predetermined process such as a process of a segment blanking period, and then a vertical synchronizing signal (hereinafter referred to as V-sync) in each of the vertical blanking period and the horizontal blanking period. ), And a horizontal synchronization signal (hereinafter referred to as H-sync) is added. Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input voice signal is converted into a digital voice signal by the A / D converter 9, and then shuffled, error correction code,
Predetermined processing such as addition of a synchronization signal and an ID signal is performed.
Further, the digital audio signal in one field period is time-axis compressed for being multiplexed in the PCM area provided in the vertical blanking period of the recorded video signal, digitally modulated, and then supplied to the switch B12.

Here, FIG. 27 shows a recording signal of one field and a switching timing chart of the switch A11 and the switch B12. The output of the FM modulator 7 is shown in FIG. 9A, the output of the PCM encoder 10 is shown in FIG.
The control signals output from the switch control circuit 32 to the switch A11 and the switch B12 are shown in FIG.
Shows the output of the adder 13. Each of the switch A11 and the switch B12 is O when the control signal is “H”, for example.
When it is N or "L", it is turned off. Based on the output of the sync separation circuit A4, the switch control circuit 32 outputs a control signal so as to provide a no-signal section before and after the PCM voice signal section, as shown in the figure, and the switch A11 and the switch B12 control the above. ON, OF according to the signal
The operation of F is performed. In adder 13, switch A11
And the output of the switch B12 are added to generate a recording signal as shown in FIG. Here, as shown in FIG. 27, from the end of the video signal data of the previous field to the PCM
The non-signal section provided in the section until the audio data starts (hereinafter referred to as gap A) and the section from the position where the PCM audio signal data ends to the vertical sync signal of the video signal (hereinafter referred to as gap B) It is provided in advance so that the video signal and the audio signal do not overlap when the audio signal or the like is recorded during dubbing. Further, in the following description, the PCM audio signal section and three sections of the gap A and the gap B are defined as the PCM area. This recording signal is amplified by the recording amplifier 14 and then recorded on the magnetic tape 1.

Next, the operation of the reproduction signal processing system of this VTR will be described. The reproduced video FM signal reproduced from the magnetic tape 1 and the PCM audio signal mixed at the time of recording are amplified by the head amplifiers 17a and 17b, and by the head switching circuit 18 based on the HSW signal output from the reference signal generation circuit 19. Switched, FM demodulator 2
3 and the PCM decoder 20.

Here, the FM demodulator 23 adopting the pulse counting method will be described with reference to FIG. Figure 2
8 (a) shows an input signal input to the FM demodulator 23, FIG. 28 (b) shows a square wave generated in the process of FM demodulation, and FIG. 28 (c) shows an output signal of the FM demodulator 23. Shown respectively. Generally, the recording band of the PCM audio signal is FM.
Since it is wider than the modulation signal, the FM demodulation result of the PCM voice signal is unknown as to which signal is demodulated as shown in FIG. Further, since the non-signal section of the gap A and the gap B becomes a signal of a constant DC level as shown in FIG. 28 (b), the FM adopting the pulse counting method is used.
In the demodulator, since there is no zero-cross point of the square wave, the demodulation waveform falls to a level outside the image amplitude as shown in FIG. 28 (c). Further, when starting the FM demodulation from the initial state outside the video amplitude (immediately after the no-signal section),
In order to obtain a predetermined FM demodulation waveform,
That is, the period Tb shown in FIG. 28C is required. Therefore, as shown in the conventional example, V-s is immediately after the no-signal section.
If ync is recorded, FM is displayed on the specified waveform.
Not demodulated, for example, a waveform as shown in FIG.

On the other hand, the PCM decoder 20 detects the PCM audio signal in the reproduced signal, performs digital demodulation, and then performs error detection, error correction, error correction, deshuffling processing, and the like, and D / A. The converter 21 converts the analog audio signal and outputs the analog audio signal.

Here, in the PCM area generator 24 in the PCM decoder 20, a signal indicating the PCM area of the reproduced video signal is converted into a PCM area signal which becomes "H" in the PCM area as shown in FIG. 29 (b). Output to the clip circuit 25. As shown in FIG. 29C, the PCM clip circuit 25 clips a signal below the black level of the reproduced video signal in the PCM area. The reproduced video signal obtained by clipping the signal below the black level in the PCM area is clamped to a predetermined level in the clamp circuit 26 and converted into a digital signal in the A / D converter 28.

In the sync separation circuit B27, the sync signal is separated from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit 29, based on the output of the sync separation circuit B27, the reproduction video signal is subjected to predetermined processing such as time axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y is obtained. Two
The color difference signals (RY) and (BY) are restored, and the sync signal is added to the D / A converters 30a, 30b, and 30c.
Is output to. The digital data of the reproduced video signal is D /
After being converted into analog data in the A converters 30a, 30b, 30c, the data is output from the output terminals 31a, 31b, 31c.

Here, as described above, the FM in the PCM area is
The reason for clipping the demodulated waveform above the black level of the reproduced video signal will be described. Since the frequency band of the PCM audio signal is wider than the frequency band of the recorded FM signal, the FM demodulation result of this portion has a larger amplitude than the video signal amplitude as shown in FIG. I don't know. Therefore, when the FM demodulated waveform in the PCM area falls below the black level of the reproduced video signal, that portion is erroneously detected as a sync signal. Since the reproduced video signal is clamped by the clamp circuit 26 based on the erroneously detected sync signal, it is not clamped at a predetermined level, and the subsequent operations such as sync separation will malfunction.

On the other hand, as shown in FIG. 28 (c), V-sync immediately after the no-signal section has a predetermined FM as described above.
It takes a period of Tb until the demodulated waveform is obtained. This T
In the period of b, the FM demodulation waveform is not demodulated into a predetermined waveform as shown in FIG. 29A, and has a waveform dropped below the black level of the reproduced video signal, for example. Also, during this period, PCM
Since it is not a region, it is not clipped by the PCM clipping circuit 25 above the black level. Therefore, the signal in the Tb period falling below the predetermined level is erroneously detected as V-sync or H-sync. Further, in the case of this conventional example, V-sync itself is not FM-demodulated into a predetermined waveform and good detection is not performed. Therefore, normal sync separation is not performed, and the reproduction signal processing operation is not performed well. Further, V-sync serves as a reference for field-based control, and if V-sync is not properly detected, field-based control in the reproduction signal processing circuit 29 does not operate normally and is unstable. It becomes a reproduced image.

Further, as described above, the VTR for recording / reproducing by dividing the video information of one field into a plurality of segments.
In, as a method of recording a digital audio signal,
There is a method of multiplexing and recording on each segment blanking of a recording video signal. Hereinafter, the VT adopting the above recording method
R will be described.

FIG. 30 shows a conceptual diagram of a recording system in which a PCM audio signal is multiplexed during a segment blanking period of a recorded video signal. FIG. 30A shows a case where the video signal of one field is 3
Fig. 3 shows how it is divided into two segments.
0 (b) shows that the video signal of one field is divided into three segments and recorded on the magnetic tape.

The shaded portion shown in the figure is the segment blanking period of the recording signal, that is, the period in which the PCM voice is inserted. The numbers shown in FIG. 30A indicate tracks on which the video information of the first, second and third segments are recorded.

FIG. 31 shows a recorded video signal in one field in this VTR. As shown in the figure, an area for recording PCM audio data for one field period is provided in a part of the segment blanking period. Hereinafter, this area is referred to as a PCM area in the same manner as above.

FIG. 32 shows a block diagram of this VTR. In the figure, 1-4, 6-9, 11-19, 21-
Since 23, 25, 26, 28, 30, and 31 are the same as those in the conventional example shown in FIG. 26, corresponding parts are designated by the same reference numerals and detailed description thereof will be omitted.

First, the recording signal processing system will be described.
A recording signal processing circuit II 33 converts the input color TV signal into a TCI signal on the basis of the sync signal output from the sync separation circuit A4, and converts the video signal of one field as shown in FIG. After being divided into three segments, a segment synchronization signal (hereinafter, S
(Referred to as -sync) and H-sync are added.

Reference numeral 34 is for adding shuffling processing, error correction code, synchronizing signal, ID signal, etc. to the digital audio signal and for storing the recorded digital audio signal of one field period within the PCM area of the segment blanking period described above. This is a PCM encoder III which performs time-axis compression on, and digitally modulates and outputs.

35 is based on the output of the sync separation circuit A4,
The switch control circuit IV controls the switches A11 and B12.

Next, the reproduction signal processing system will be described. Three
Reference numeral 6 denotes an audio signal in the PCM area within the segment blanking period in the reproduced signal output from the head switching circuit 18, which is converted into digital data, digitally demodulated and converted into a reproduced digital audio signal, and then time-axis expansion, A PCM decoder II that performs error detection, error correction, error correction, deshuffling processing, and the like.

Further, 37 is a signal which indicates a PCM area detected in the PCM decoder II 36 and which is sent to the PCM clip circuit 25.
It is a PCM area generator III for outputting to.

Reference numeral 38 denotes a sync separation circuit C, 3 for separating a sync signal from the reproduced video signal output from the clamp circuit 26.
9 is a reproduction TC based on the output of the sync separation circuit C38.
After performing time-axis correction, dropout compensation, etc. on the I signal, reproduction that restores the original luminance signal Y and the two color difference signals (RY) and (BY) and adds a synchronization signal, etc. The signal processing circuit II.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit II33. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. The recording signal processing circuit II33 converts the input video signal into a TCI signal based on the output of the sync separation circuit A4, and performs a predetermined process such as a process of a segment blanking period. Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input audio signal is converted into a digital audio signal by the A / D converter 9, and then the PCM encoder III 34 performs shuffling processing, error correction code, synchronization signal, ID signal addition, etc. Predetermined processing is performed. Further, since the digital audio signal in one field period is multiplexed in the PCM area provided in the segment blanking period of the recorded video signal, 3
It is divided into two parts, subjected to time-base compression, subjected to digital modulation, and then supplied to the switch B12.

FIG. 33 shows a recording signal for one field and a switching timing chart of the switches A11 and B12. The output of the FM modulator 7 is shown in (a), the output of the PCM encoder III 34 is shown in (b), and the switches A11 and B12 are shown in (c) and (d).
To the control signal output from the switch control circuit IV35,
The output of the adder 13 is shown in FIG. Switch A1
1, the switch B12 is ON when the control signal is "H", and is OFF when the control signal is "L". Based on the output of the sync separation circuit A4, the switch control circuit IV35 outputs a control signal so as to provide a no-signal section before and after the PCM voice signal section, as shown in the figure, and the switch A11 and the switch B12 control the above. ON / OFF operation is performed according to the signal. The adder 13 adds the outputs of the switch A11 and the switch B12 to generate a recording signal as shown in FIG. Here, as shown in the figure, a section from the end of the video signal data of the previous segment to the start of the PCM audio data (hereinafter referred to as gap A) and the position of the end of the PCM audio signal data, The no-signal section provided in the section up to the beginning of the segment (hereinafter referred to as the gap B) is for preventing the video signal and the audio signal from overlapping when recording an audio signal or the like during after-recording. Further, in the following description, the PCM audio signal section and the gap A and the gap B
The three sections are defined as PCM areas. This recording signal is amplified by the recording amplifier 14 and then recorded on the magnetic tape 1.

Next, the operation of the reproduction signal processing system of this VTR will be described. The reproduced video FM signal reproduced from the magnetic tape 1 and the PCM audio signal mixed at the time of recording are amplified by the head amplifiers 17a and 17b, and by the head switching circuit 18 based on the HSW signal output from the reference signal generation circuit 19. Switched, FM demodulator 2
3 and the PCM decoder II 36.

PC in the segment blanking period output from the FM demodulator 23 adopting the pulse counting method
The result of FM demodulation of the signal in the M region is shown in FIG. The figure will be described below. As described above, since the recording band of the PCM audio signal is wider than that of the FM modulated signal,
The FM demodulation result of the M audio signal is unknown as shown in FIG. Further, the demodulated waveforms of the gap A and the gap B, which are non-signal sections, fall to a level outside the video amplitude. Therefore, as described above, when the FM demodulation is started from the initial state outside the video amplitude (immediately after the non-signal section), a certain period of time Tb is required to obtain a predetermined FM demodulation waveform.

Therefore, S-sync immediately after the no-signal section
Is not FM-demodulated into a predetermined waveform, for example, as shown in FIG.
The waveform will be as shown in.

On the other hand, the PCM decoder II 36 detects the PCM audio signal within the segment blanking period in the reproduced signal, performs digital demodulation, and then performs error detection, error correction, error correction, deshuffling processing and the like. Then, the D / A converter 21 converts the analog audio signal and outputs the analog audio signal.

Here, in the PCM area generator III37 in the PCM decoder II36, the signal indicating the PCM area of the reproduced video signal is PCM clipped by the PCM area signal which becomes "H" in the PCM area as shown in FIG. 34 (b). Circuit 25
Output to. In the PCM clip circuit 25, FIG.
As shown in, the signal below the black level of the reproduced video signal in the PCM area is clipped. The reproduced video signal obtained by clipping the signal below the black level in the PCM area is clamped to a predetermined level by the clamp circuit 26, and the A / D converter 28
Is converted into a digital signal at.

In the sync separation circuit C38, the sync signal is separated from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit II39, based on the output of the sync separation circuit C38, the reproduction video signal is subjected to predetermined processing such as time axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y. And two color difference signals (R-Y) and (B-Y), and a sync signal is added to the D / A converters 30a, 30b, 30.
It is output to c. The digital data of the reproduced video signal is D
After being converted into analog data in the A / A converters 30a, 30b, 30c, output terminals 31a, 31b, 31c
Is output by.

However, as shown in FIG. 34 (a), the S-sync immediately after the non-signal section has a predetermined F as described above.
Since it takes a period of Tb until the M demodulation waveform is obtained,
The waveform is not demodulated into a predetermined waveform, and has a waveform dropped below the black level of the reproduced video signal, for example. Also, during this period, PC
Since it is not in the M region, PCM as shown in FIG.
The clip circuit 25 does not clip above the black level. Therefore, the signal in the Tb period falling below the predetermined level is erroneously detected as S-sync or H-sync. Further, in the case of the conventional example, since S-sync is not FM-demodulated into a predetermined waveform, good detection cannot be performed. Therefore, normal sync separation is not performed, and the reproduction signal processing operation is not performed well. Further, since the S-sync is not properly detected, the reproduced signal processing circuit II39
Control does not work properly, resulting in an unstable playback image.

[0042]

In the conventional video signal recording / reproducing apparatus as described above, when the PCM audio signal is inserted and recorded in a part of the vertical blanking period of the FM-modulated video signal at the time of recording, Since a non-signal section is provided between the PCM audio signal and the recorded video signal for recording, when the reproduced FM video signal is subjected to FM demodulation during reproduction, the mixed PCM audio signal and the no-signal section are also recorded. Since the FM demodulation is performed, the vertical blanking data of the reproduced video signal immediately after the non-signal section is not FM demodulated into the original waveform. Therefore, even if the signal in the PCM area of the reproduced video signal is clipped by the PCM clipping circuit 25, Tb shown in FIG.
There is a problem in that the period signal is erroneously detected as a synchronization signal, the synchronization separation is not normally performed, and an unstable reproduced image is generated. Further, if the period from the end of the gap B to V-sync of the recorded video signal is not sufficient, there is a problem that the influence of the non-signal section affects the demodulation waveform of V-sync.

Further, in the video signal recording / reproducing apparatus which records and reproduces the video information of one field by dividing it into a plurality of segments as described above, the PCM of one field period is included in a part of each segment blanking period of the recorded video signal. When dividing the audio signal into multiple blocks and inserting and recording
Since a non-signal section is provided between the PCM audio signal and the recorded video signal for recording, when the reproduced FM video signal is subjected to FM demodulation during reproduction, the mixed PCM audio signal and the no-signal section are also recorded. Since the FM demodulation is performed, the segment blanking data of the reproduced video signal immediately after the non-signal section is not FM demodulated into the original waveform. Therefore, even if the PCM area signal of the reproduced video signal is clipped by the PCM clipping circuit 25, the signal in the Tb period shown in FIG. 34 (c) is erroneously detected as a sync signal, and the sync separation is not normally performed, which is unstable. There was a problem such as a reproduced image. Further, when the period from the end of the gap B to the S-sync of the recorded video signal is not sufficient, there is a problem that the influence of the non-signal section affects the demodulated waveform of the S-sync.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to accurately perform the sync separation of the reproduced video signal immediately after the non-signal section and to perform the stable reproduction in the field unit. An object of the present invention is to obtain a video signal recording / reproducing device which becomes a video signal.

[0045]

A video signal recording / reproducing apparatus according to the present invention is located immediately after a PCM audio signal multiplexed in a vertical blanking period of a recorded video signal, that is, immediately before V-sync of the recorded video signal. Since a signal of a single frequency (corresponding to the white level to the black level of the video signal) within the carrier frequency of the FM-modulated recording signal is generated and multiplexed in the no-signal section, during reproduction , V-sync of the reproduced video signal after FM demodulation has a predetermined waveform so that the synchronous separation of the reproduced video signal is normally performed.

Further, generally, when reproducing the PCM audio signal inserted in the vertical blanking period at the time of recording, a signal (hereinafter referred to as a run-up signal) serving as a reference for the clock pull-in at the time of reproduction is shown in FIG. Before and after the digital audio signal (ie preamble and postamble) as shown
Need to be inserted into.

Here, in the video signal recording / reproducing apparatus according to the present invention, a single signal (corresponding to between the white level and the black level of the video signal) within the carrier frequency of the FM-modulated recording signal of the run-up signal is used. Select the frequency of, PCM at the time of recording
Immediately after the audio signal, that is, V-syn of the recorded video signal
Since it is also inserted in the no-signal section immediately before c, the reproduced video signal can be normally separated by the V-sync FM-demodulated into a predetermined waveform without erroneously detecting the synchronous signal during reproduction. It is the one.

Further, the video signal recording / reproducing apparatus according to the present invention, at the time of reproduction, immediately after the PCM audio signal of the reproduced FM signal,
That is, a signal of a single frequency (corresponding to the white level to the black level of the video signal) within the carrier frequency of the FM-modulated recording signal is generated and multiplexed in the no-signal section immediately before V-sync. Since V-sync of the reproduced video signal after FM demodulation has a predetermined waveform at the time of reproduction, the synchronous separation of the reproduced video signal is normally performed.

Further, the video signal recording / reproducing apparatus according to the present invention is arranged such that V-sync is started from the end of the no signal section of the PCM area.
If a sufficient time period is taken, the region where the period Tb, which is a waveform lower than the black level of the video signal immediately after the non-signal section, is added to the original PCM region is clipped when clipping to the black level of the video signal or more. With this configuration, the reproduction video signal is normally separated in synchronization during reproduction.

Further, in the video signal recording / reproducing apparatus according to the present invention, there is no signal section immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the recording video signal, that is, immediately before S-sync of the recording video signal. Since a signal having a single frequency within the carrier frequency of the FM-modulated recording signal (corresponding to the white level to the black level of the video signal) is generated and multiplexed, the FM demodulation is performed at the time of reproduction. The S-sync of the subsequent reproduced video signal is such that a predetermined waveform is obtained and the synchronous separation of the reproduced video signal is normally performed.

Further, generally, when reproducing a PCM audio signal inserted in a plurality of segment blanking periods of a recorded video signal at the time of recording, FIG. 17A shows a run-up signal which is a reference of a clock pull-in at the time of reproduction. Therefore, it is necessary to insert it before and after the digital audio signal (that is, preamble and postamble).

Here, the video signal recording / reproducing apparatus according to the present invention is a single signal (corresponding to a range from the white level to the black level of the video signal) within the carrier frequency of the FM-modulated recording signal of the run-up signal. PCM multiplexed in multiple segment blanking periods of recorded video signal
Immediately after the audio signal, that is, S-sync of the recorded video signal
Since it is also inserted in the no-signal section immediately before, the reproduction video signal can be normally separated by the S-sync FM-demodulated into a predetermined waveform without erroneously detecting the synchronization signal during reproduction. It was done.

Further, the video signal recording / reproducing apparatus according to the present invention, at the time of reproduction, immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the reproduction FM signal, that is, immediately before S-sync of the reproduction FM signal. F in no signal section
Since a signal having a single frequency (corresponding to the white level to the black level of the video signal) within the carrier frequency of the M-modulated recording signal is generated and multiplexed, during reproduction, after FM demodulation The S-sync of the reproduced video signal is such that a predetermined waveform is obtained and the synchronous separation of the reproduced video signal is normally performed.

Further, the video signal recording / reproducing apparatus according to the present invention is a signalless section immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the record video signal, that is, immediately before S-sync of the record video signal. When the period from the end of the above to S-sync is sufficient, when clipping to a level higher than the black level of the video signal, a period in which the waveform falls below the black level of the video signal immediately after the non-signal section in the original PCM area. Since the region to which Tb is added is clipped, the reproduction video signal is normally separated in synchronization during reproduction.

[0055]

The video signal recording / reproducing apparatus according to the present invention is used immediately after the PCM audio signal during recording, that is, V of the recorded video signal.
Since a signal of a single frequency corresponding to the white level to the black level of the video signal is recorded in the no-signal section immediately before -sync, the sync signal is not detected by mistake and the FM signal is displayed in a predetermined waveform.
The demodulated V-sync can normally perform the sync separation of the reproduced video signal.

Further, the video signal recording / reproducing apparatus of the present invention is inserted into the preamble and the postamble at the time of recording, and at the time of pulling in the clock at the time of reproduction, the reference run-up signal corresponds to the white level to the black level of the video signal. A single frequency to be used is selected, and is inserted into a no-signal section immediately after the PCM audio signal at the time of recording, that is, immediately before V-sync of the recorded video signal. FM-demodulated V-sync waveform
As a result, it is possible to normally perform the sync separation of the reproduced video signal.

Further, the video signal recording / reproducing apparatus of the present invention, when reproducing, immediately after the PCM audio signal of the reproduced FM signal,
That is, since a signal of a single frequency corresponding to the white level to the black level of the video signal is inserted in the no-signal section immediately before V-sync and the FM demodulation operation of the reproduced FM signal is performed, the sync signal is erroneously detected. FM to a predetermined waveform without
The demodulated V-sync can normally perform the sync separation of the reproduced video signal.

Further, the video signal recording / reproducing apparatus according to the present invention starts from V-syn from the end of the non-signal section of the PCM area.
When the period up to c is sufficient, when clipping above the black level of the video signal, the region obtained by adding the period Tb, which is a waveform lower than the black level of the video signal immediately after the non-signal section, to the original PCM region. Since clipping is performed, the sync separation of the reproduced video signal can be normally performed by the V-sync FM-demodulated into a predetermined waveform without erroneously detecting the sync signal.

Further, the video signal recording / reproducing apparatus of the present invention is arranged immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the recording video signal, that is, in the no signal section immediately before S-sync of the recording video signal. Since a signal of a single frequency corresponding to the white level to the black level of the video signal is recorded, the sync signal of the reproduced video signal is separated by S-sync which is FM demodulated into a predetermined waveform without erroneously detecting the sync signal. Can be done normally.

Further, the video signal recording / reproducing apparatus of the present invention is inserted into the preamble and the postamble at the time of recording, and at the time of pulling in the clock at the time of reproduction, the reference run-up signal is changed from the white level of the video signal to the black level. Since a corresponding single frequency is selected and is inserted immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the recorded video signal, that is, also in a no-signal section immediately before S-sync of the recorded video signal, reproduction is performed. At this time, the S-sync is FM-demodulated into a predetermined waveform without erroneously detecting the sync signal.
As a result, it is possible to normally perform the sync separation of the reproduced video signal.

Further, the video signal recording / reproducing apparatus according to the present invention is arranged immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the reproduced FM signal, that is, the reproduced F signal.
Since a signal of a single frequency corresponding to the white level to the black level of the video signal is inserted in the no-signal section immediately before S-sync of the M signal and the FM demodulation operation of the reproduced FM signal is performed, the synchronization signal is changed. FM in a predetermined waveform without false detection
By the demodulated S-sync, the sync separation of the reproduced video signal can be normally performed.

Further, the video signal recording / reproducing apparatus of the present invention is arranged in the no signal section immediately after the PCM audio signal multiplexed in a plurality of segment blanking periods of the record video signal, that is, immediately before S-sync of the record video signal. When the period from the end to the S-sync is sufficient, the original PCM is used when clipping the video signal to the black level or higher.
Since the region added with the period Tb in which the waveform becomes a waveform lower than the black level of the video signal immediately after the no-signal section is clipped to the region, the S-demodulated to the predetermined waveform S- With sync, it is possible to normally perform synchronous separation of reproduced video signals.

[0063]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a VTR according to an embodiment of the present invention. In FIG. 1, 1 to 31 are the same as those in the conventional example shown in FIG. Detailed explanation is omitted.

In FIG. 1, 40 is a signal generator for generating a signal of a single frequency, 41 is a switch C, 42 is an adder, and 43 is a switch A11, a switch B12, and a switch C41 based on the output of the sync separation circuit A4. It is a switch control circuit II for controlling the.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit 5. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. In the recording signal processing circuit 5, the sync separation circuit A
Based on the output of No. 4, it is converted into a TCI signal and subjected to a predetermined process such as a process of a segment blanking period. Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input voice signal is converted into a digital voice signal by the A / D converter 9, and then shuffled, error correction code,
Predetermined processing such as addition of a synchronization signal and an ID signal is performed.
Further, the digital audio signal in one field period is time-axis compressed for being multiplexed in the PCM area provided in the vertical blanking period of the recorded video signal, digitally modulated, and then supplied to the switch B12.

Further, the signal generator 40 generates a signal having a single frequency, for example, a signal having a frequency corresponding to the gray level of the video signal.

Here, the recording signal of one field and the switch A11, the switch B12, and the switch C4 are shown in FIG.
1 shows a switching timing chart of No. 1; In the figure,
Gray is a signal of a single frequency corresponding to the gray of the recorded FM signal. 2 (a) shows the output of the adder 13, FIG. 2 (b) shows the output of the signal generator 40, and FIG.
The switches A11 and B1 are shown in (d) and (e).
2. Switch control circuit II4 output to switch C41
The control signal output from 3 is shown in FIG.
Shows the output of. In the figure, the control signals output to the switches A11 and B12 are the same as in the conventional example. Similarly to the conventional example, the switch C41 is turned on when the control signal is "H" and turned off when it is "L". Based on the output of the sync separation circuit A4, the switch control circuit II43, as shown in the figure, provides a signalless section as in the conventional example, and a signal of a single frequency corresponding to a gray level in the section of the gap B. Output a control signal so that the switch A11, the switch B12, and the switch C41 are turned on and off according to the control signal.
The operation of F is performed. Then, after the outputs of the switch A11 and the switch B12 are added in the adder 13,
In the adder 42, the outputs of the switch C41 and the adder 13 are added, and a signal of a single frequency corresponding to a gray level is added to the non-signal section of the gap B to generate a recording signal as shown in FIG. ..

Then, as in the conventional example, it is amplified by the recording amplifier 14 and recorded on the magnetic tape 1 by the video amplifiers 15a and 15b.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area including the gap A and the gap B to which a signal of a single frequency corresponding to the gray level is added are the same as those in the conventional example. Similarly, the reference signal generating circuit 1 is amplified by the head amplifiers 17a and 17b.
9 is switched by the head switching circuit 18 based on the HSW signal output from the FM demodulator 23 and the PC.
It is output to the M decoder 20.

First, the PCM decoder 20 detects the PCM voice signal in the reproduced signal and digitally demodulates it as in the conventional example, and then performs error detection, error correction, and error correction.
Processing such as deshuffling processing is performed to restore the original digital audio signal. Then, the D / A converter 21
Is converted into an analog audio signal and output.

Next, in the FM demodulator 23, the section of the reproduced FM video signal and the section of the gap B in which the signal corresponding to the gray level is added to a part of the vertical blanking period of the reproduced FM video signal. The containing PCM domain signal is FM demodulated.

The operation of the FM demodulator 23 in the VTR of this embodiment will be described with reference to FIG. FIG.
3A shows the input signal input to the FM demodulator 23, FIG. 3B shows the square wave generated in the process of FM demodulation, and FIG. 3C shows the FM demodulator. The output signals of 23 are shown respectively. Since a signal of a single frequency corresponding to a gray level is inserted in the section of the gap B of the reproduced signal input to the FM demodulator 23 as shown in FIG. Thus, there is a zero-cross point of the square wave. Then, as shown in FIG.
The FM demodulation result in the M audio signal section becomes larger than the video signal amplitude as in the conventional example, and it is not known what kind of waveform is demodulated, but the section in the gap B is demodulated into a gray level signal, and the gap B Since the signal immediately after the section (1) is also FM demodulated following the gray level signal, the demodulated waveform does not drop to a level outside the video amplitude as described in the conventional example.

Therefore, V- immediately after the section of the gap B
As shown in FIG. 4A, sync is FM-demodulated into a predetermined waveform. Next, in the PCM clip circuit 25, as in the conventional example, the PCM region signal as shown in FIG. 4B is used as a reference, and the F in the PCM region is provided as shown in FIG. 4C.
The M demodulation waveform is clipped above the black level of the reproduced video signal. Then, the reproduced video signal in which the signal of the black level or lower in the PCM area is clipped is clamped to a predetermined level in the clamp circuit 26 and converted into a digital signal in the A / D converter 28. Also, the sync separation circuit B27
At, the sync signal is separated from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit 29, based on the output of the sync separation circuit B27, the reproduction video signal is subjected to predetermined processing such as time axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y. And the two color difference signals (RY) and (BY) are restored, and the synchronization signal is added to the D / A converter 30a,
After being converted into analog data in 30b, 30c, it is output by the output terminals 31a, 31b, 31c.

Therefore, the VTR of the present embodiment is P
Since a signal of a single frequency corresponding to the gray level is inserted in the no signal section of the CM area, V-sync is FM demodulated into a predetermined waveform, and the sync separation is normally performed in the sync separation circuit B27. The signal processing operation is performed well. Further, since the signal falling below the black level in the vertical blanking period of the reproduced signal can be reliably clipped, the sync signals such as V-sync and H-sync are detected well, and the sync separation circuit B27 performs the sync separation. Since it is performed normally, the reproduction signal processing circuit 29
The field-by-field control also operates normally, and a stable reproduced image can be obtained.

Example 2. Next, a second embodiment will be described. FIG. 5A shows a PCM audio signal inserted in the vertical blanking period of one field period. As shown in the figure, the structure of the PCM audio signal in the 1-field period is provided with a preamble and a postamble section at the beginning and the end of the original digital audio data. In both sections, a clock is pulled in during reproduction. At this time, a reference run-up signal is inserted. These three periods are combined to form a PCM audio signal section of one field period. Note that the run-up signal is selected to have a single frequency corresponding to the black level of the video signal.

FIG. 6 is a block diagram showing the structure of the VTR of this embodiment. In FIG. 6, 1-9 and 11-31 are the same as those in the conventional example shown in FIG. Therefore, detailed description thereof will be omitted.

In the figure, 50 is a PCM encoder II.
As in the conventional example, the digital audio signal is shuffled, the error correction code, the synchronization signal, the ID signal,
Etc. are added, time-axis compression is performed so that the recorded digital audio signal for one field period is contained in the PCM area, digital modulation is performed, and the signal is output. Also at this time,
Although not described in the conventional example, the run-up signal is inserted in the preamble and the postamble. 51 is a switch A11 and a switch B based on the output of the sync separation circuit A4.
12 is a switch control circuit III for controlling 12.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit 5. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. The recording signal processing circuit 5 is a sync separation circuit A4.
After converting the input video signal into a TCI signal based on the output of, the predetermined processing such as the processing of the segment blanking period is performed. Next, after being converted into an analog signal by the D / A converter 6 and FM-modulated by the FM modulator 7, the switch A
11 is supplied. Similarly, the input audio signal is A / D
After being converted into a digital audio signal by the converter 9, P
It is output to the CM encoder II50. PCM encoder
The II50 inserts a reference run-up signal into the preamble and postamble during reproduction and clock pull-in in a predetermined process similar to the conventional example.

Here, as described in the conventional example, when there is a no-signal section, a signal in the PCM region, that is, a mixed digital audio signal, is subjected to FM demodulation during reproduction.
In addition, since FM demodulation is also applied to the no-signal section, the vertical blanking data of the reproduced video signal immediately after the no-signal section is not FM-demodulated into the original waveform (see FIG. 29). Therefore, as shown in FIG. 5B, a section obtained by adding the section of the gap B described in the conventional example to the section of the original postamble is set as the postamble, and a single level corresponding to the black level from the white level of the video signal is obtained. Insert the run-up signal of frequency.

Therefore, during reproduction, when the reproduced FM video signal and the signal in the PCM area are FM-demodulated in the FM demodulator 23, the signal in the postamble section is FM-demodulated into a signal in the video signal amplitude, and the postamble section is reproduced. The vertical blanking data immediately after is also FM-demodulated into the original waveform.

Further, by changing the signal of a single frequency corresponding to the white level to the black level of the video signal to be inserted in the no-signal section to the run-up signal, a new signal corresponding to the white level to the black level of the video signal is newly added. It is not necessary to provide a circuit for generating a signal of one frequency in the recording signal processing system.

FIG. 7 shows a recording signal of one field and a switching timing chart of the switch A11 and the switch B12. The output of the FM modulator 7 is shown in (a), the output of the PCM encoder II50 is shown in (b), and the switch A11 and the switch B12 are shown in (c) and (d).
The control signal output from the switch control circuit III 51 is shown in FIG. 3, and the output of the adder 13 is shown in FIG. Switch A
The switch 11 and the switch B12 are, for example, ON when the control signal is "H" and OFF when the control signal is "L". Based on the output of the sync separation circuit A4, the switch control circuit III 52 sets a no-signal section at the beginning of the PCM audio signal section, that is, a section of the gap A, and does not set a no-signal section at the end, as shown in FIG. The control signal is output, and the switch A11 and the switch B12 are turned on and off according to the control signal. The adder 13 adds the outputs of the switch A11 and the switch B12 to generate a recording signal as shown in FIG.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area are amplified by the head amplifiers 17a and 17b and output from the reference signal generation circuit 19 as in the conventional example. Based on the signal, it is switched by the head switching circuit 18 and output to the FM demodulator 23 and the PCM decoder 20.

In the PCM decoder 20, the PCM audio signal in the reproduced signal is detected with reference to the run-up signal inserted in the preamble and the postamble as in the conventional example, and after digital demodulation, error detection and error are performed. Processing such as correction, error correction, and deshuffling processing is performed, and the D / A converter 21 converts the analog signal and outputs the analog signal.

In the FM demodulator 23, the reproduced FM video signal and P
The signal in the CM area is FM demodulated. Here, FIG.
As shown in (a), the signal in the PCM region, that is, the demodulation result of the digital audio data is larger than the amplitude of the video signal as in the conventional example, and although it is not known what the waveform is, the postamble including the no signal section is included. Since a run-up signal of a single frequency corresponding to the white level to the black level of the video signal is inserted in the signal, FM demodulation is performed on the signal within the video amplitude, and the vertical blanking data immediately after the non-signal section is also original. The waveform is FM demodulated.

Therefore, similarly to the first embodiment, the demodulation waveform of the signal immediately after the postamble does not drop to a level outside the video amplitude, and V-sync is also FM demodulated into a predetermined waveform. Then, in the PCM clip circuit 25, as shown in FIGS. 8B and 8C, the reproduced video signal obtained by clipping the signal below the black level of the PCM region based on the output of the PCM region generator 24 is clamped by the clamp circuit 26. Is clamped to a predetermined level in the A / D converter 28
Is converted into a digital signal at. Further, the sync separation circuit B27 separates the sync signal from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit 29, based on the output of the sync separation circuit B27, the reproduction video signal is subjected to predetermined processing such as time axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y. And two color difference signals (RY), (B-
Y) is restored, a synchronizing signal is added thereto, converted into analog data in the D / A converters 30a, 30b, 30c, and then output from the output terminals 31a, 31b, 31c.

Therefore, the VTR of the present embodiment is P
Since a run-up signal of a single frequency corresponding to the white level to the black level of the video signal is inserted in the no signal section of the CM area, V-sync has a predetermined waveform FM as in the first embodiment.
Since the signals are demodulated and the normal sync separation is performed in the sync separation circuit B27, the reproduction signal processing operation is favorably performed. Further, since V-sync and H-sync are well detected, normal sync separation is performed in the sync separation circuit B27, and the field-based control in the reproduction signal processing circuit 29 also operates normally and is stable. A reproduced image can be obtained.

Example 3. Next, a third embodiment will be described. FIG. 9 is a block diagram showing the configuration of the VTR of this embodiment. In FIG. 9, 1 to 32 are the same as the conventional example shown in FIG. Is omitted.

In FIG. 9, 60 is a signal generator II for generating a signal of a single frequency, 61 is a switch D, 62 is an adder, and 63 is a PCM area generator II.

Next, the operation of the recording system of this VTR will be described. Since the operation of the recording system is the same as that of the conventional example, it will be briefly described. The input color TV signal is converted into an A / D converter 3
It is converted into a digital video signal by a, 3b, and 3c and output to the recording signal processing circuit 5. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. The recording signal processing circuit 5 converts the input video signal into a TCI signal based on the output of the sync separation circuit A4, and then performs a predetermined process such as a process of a segment blanking period. Next, after being converted into an analog signal by the D / A converter 6 and FM-modulated by the FM modulator 7, the switch A
11 is supplied. Similarly, the input audio signal is A / D
After being converted into a digital audio signal by the converter 9,
The PCM encoder 10 performs predetermined processing such as shuffling processing, error correction code, synchronization signal, and addition of ID signal. Further, the digital audio signal for one field period is P
It is supplied to the switch B12 after being subjected to time-base compression for multiplexing in the CM area, digitally modulated, and then supplied.

Then, according to the control signal output from the switch control circuit 32, the switch A11 and the switch B12 are
Is turned on and off, and a recording signal as shown in FIG. 27 (e) is generated in the adder 13 and recorded on the magnetic tape 1.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area including the gap A and the gap B are amplified by the head amplifiers 17a and 17b as in the conventional example, and the reference signal is generated. Circuit 1
Switching is performed by the head switching circuit 18 based on the HSW signal output from 9.

Further, the signal generator II60 generates a signal having a single frequency, for example, a signal having a single frequency corresponding to the gray level of the FM video signal, as in the first embodiment.

Now, referring to FIG. 10, the switch D61,
The operation of the adder 62 and the PCM area generator II 63 will be described. FIG. 10 shows a reproduction signal of one field and a switch D.
61 shows a switching timing diagram of the switch 61, and the switch D
Similarly to the switches A11 and B12, 61 is turned on when the control signal is "H" and turned off when the control signal is "L". The output of the head switching circuit 18 is shown in (a) of the figure, the output of the signal generator 60 is shown in (b), and the control signal output from the PCM area generator II 63 to the switch D61 is shown in (c). The output of the adder 62 is shown in FIG. The PCM area generator II 63 detects the PCM area from the reproduced FM signal output from the head switching circuit 18, outputs a PCM area signal which becomes "H" in the PCM area to the PCM clip circuit 25, and is shown in the same figure. In this way, the control signal which becomes "H" in the section of the gap B is output to the switch D61. The switch D61 is turned on and off according to the control signal. In addition, in the adder 62, the output of the head switching circuit 18 and the output of the switch D61 are added, and as shown in FIG. 7D, reproduction is performed in which a signal of a single gray level frequency is added to the section of the gap B. An FM signal is generated. This reproduced FM signal is output to the FM demodulator 23 and the PCM decoder 20.

Similar to the conventional example, the PCM decoder 20 detects the PCM audio signal in the reproduced signal with reference to the run-up signals inserted in the preamble and the postamble, performs digital demodulation, and then performs error detection and error. Processing such as correction, error correction, and deshuffling processing is performed, and the D / A converter 21 converts the analog signal and outputs the analog signal.

In the FM demodulator 23, the FM demodulator 23 is similar to the first embodiment.
Since demodulation is performed, the section of the gap B is demodulated into a gray level signal, and the signal immediately after the section of the gap B is also FM demodulated following the gray level signal.
As described in the conventional example, the demodulated waveform immediately after the section of the gap B does not fall to a level outside the video amplitude. Further, V-sync immediately after the section of the gap B is shown in FIG.
As shown in (a), FM demodulation is performed into a predetermined waveform.

Then, in the PCM clip circuit 25, the output from the PCM area generation circuit 24 is shown in FIG.
Based on the PCM area signal as shown in FIG. 4, the reproduced video signal in which the signal below the black level in the PCM area is clipped is clamped to a predetermined level in the clamp circuit 26 as shown in FIG. It is converted into a digital signal in the container 28. Further, the sync separation circuit B27 separates the sync signal from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit 29, based on the output of the sync separation circuit B27, the reproduction video signal is subjected to predetermined processing such as time axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y.
And two color difference signals (RY) and (BY) are restored,
A sync signal is added to the D / A converters 30a, 30b,
After being converted into analog data in 30c, it is output by the output terminals 31a, 31b, 31c.

Therefore, the VTR of this embodiment is set to P
Since a signal having a single frequency corresponding to a gray level is inserted in the no signal section of the CM area to perform the FM demodulation operation of the reproduced FM video signal, the V-sync is performed as in the first embodiment.
Is subjected to FM demodulation into a predetermined waveform, and normal sync separation is performed in the sync separation circuit B27, so that the reproduction signal processing operation is favorably performed. In addition, V-sync and H-s
Since the sync is satisfactorily detected, the sync separation circuit B
Normal sync separation is performed in 27, field-by-field control in the reproduction signal processing circuit 29 also operates normally, and a stable reproduced image can be obtained.

Example 4. Next, a fourth embodiment will be described. FIG. 11 is a block diagram showing the configuration of the present embodiment. In FIG. 11, 1 to 32 are the same as the conventional example shown in FIG.

In the figure, reference numeral 70 denotes a PCM area signal generated from the PCM area generator 24 for a predetermined time.
A delay circuit for delaying, 71 is an OR circuit.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit 5. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. The recording signal processing circuit 5 is a sync separation circuit A4.
After converting the input video signal into a TCI signal based on the output of, the predetermined processing such as the processing of the segment blanking period is performed. Next, after being converted into an analog signal by the D / A converter 6 and FM-modulated by the FM modulator 7, the switch A
11 is supplied. Similarly, the input audio signal is A / D
After being converted into a digital audio signal by the converter 9,
The PCM encoder 10 performs predetermined processing such as shuffling processing, error correction code, synchronization signal, and addition of ID signal. Further, the digital audio signal for one field period is P
It is supplied to the switch B12 after being subjected to time-base compression for multiplexing in the CM area, digitally modulated, and then supplied.

Then, in accordance with the control signal output from the switch control circuit 32, the switch A11 and the switch B12 are
Is turned on and off, and a recording signal as shown in FIG. 27 (e) is generated in the adder 13 and recorded on the magnetic tape 1.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area including the gap A and the gap B are amplified by the head amplifiers 17a and 17b as in the second embodiment, and the reference signal is obtained. Generation circuit 1
Switching is performed by the head switching circuit 18 based on the HSW signal output from 9. The reproduction signal output from the head switching circuit 18 is sent to the FM demodulator 23 and the PCM.
It is output to the decoder 20.

Similar to the conventional example, the PCM decoder 20 detects the PCM audio signal in the reproduced signal with reference to the run-up signals inserted in the preamble and the postamble, performs digital demodulation, and then performs error detection and error. Processing such as correction, error correction, and deshuffling processing is performed, and the D / A converter 21 converts the analog signal and outputs the analog signal.

Next, the operation of the FM demodulator 23 will be described. FIG. 12A shows an output waveform of the FM demodulator 23.
Similar to the conventional example, by performing pulse count type FM demodulation on the gap B which is a no-signal section, the vertical blanking data immediately after the PCM area has a waveform lower than the black level of the video signal (this period Tb as in the example
If the period from the end of the gap B to V-sync is sufficiently long, V-sync is demodulated into a predetermined waveform.

Next, in the PCM area generator 24, as in the conventional example, as shown in FIG.
For example, a PCM region signal that becomes “H” in the M region is output, but as shown in FIG.
The delay circuit 70 delays the PCM region signal so as to include the period b. Then, the P output from the delay circuit 70 is output.
CM area signal and P output from the PCM area generator 24
The CM area signal is generated by the OR circuit 71 into a signal including the Tb period in addition to the PCM region period as shown in FIG.

The PCM clip circuit 25 shown in FIG.
On the basis of the PCM area signal indicated by, the image signal is clipped to the black level or higher as shown in FIG.

Then, the reproduced video signal in which the signal below the black level in the PCM area is clipped is clamped to a predetermined level in the clamp circuit 26 and converted into a digital signal in the A / D converter 28. Further, the sync signal is separated from the reproduced video signal output from the clamp circuit 26 based on the output of the sync separation circuit B27. In the reproduction signal processing circuit 29, based on the output of the sync separation circuit B27, the reproduction video signal is subjected to time axis correction, dropout compensation,
After a predetermined process such as absorption of the segment blanking portion is performed, the original luminance signal Y and two color difference signals (R-
Y), (B-Y), the sync signal is added,
After being converted into analog data in the D / A converters 30a, 30b, 30c, output terminals 31a, 31b, 31
It is output by c.

Therefore, in the VTR of this embodiment, when the period from the end of the non-signal section of the PCM area to V-sync is sufficient, that is, the FM demodulator 23 causes V-
When the sync is demodulated into a predetermined waveform, when clipping above the black level of the video signal, an area obtained by adding a period Tb in which the waveform has a waveform lower than the black level of the video signal immediately after the non-signal section to the original PCM area. Since it is configured to be clipped, V-sync and H-sync are satisfactorily detected, and normal sync separation is performed in the sync separation circuit B27. Therefore, the reproduction signal processing circuit 29 also controls the field unit normally. It is possible to obtain stable reproduced images.

Example 5. Next, a fifth embodiment will be described. FIG. 13 is a block diagram showing the structure of a VTR according to an embodiment of the present invention. In FIG. 13, 1-4, 6-9, 1 are shown.
1-19, 21-23, 25-26, 28, 30-31
Since this is the same as the conventional example shown in FIG. 26, the same reference numerals are given to the corresponding portions, and detailed description thereof will be omitted. Also,
Since 33, 34, 36 to 39 are the same as the conventional example shown in FIG. 32, detailed description thereof will be omitted.

In FIG. 13, as in the first embodiment, 40
Is a signal generator for generating a signal of a single frequency, 41 is a switch C, 42 is an adder, and 100 is a switch control circuit for controlling the switches A11, B12 and C41 based on the output of the sync separation circuit A4. It is V.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit II33. Also,
The sync signal is separated from the color TV signal in the sync separation circuit A4. The recording signal processing circuit II33 converts the input video signal into a TCI signal based on the output of the sync separation circuit A4, and performs predetermined processing such as processing of a segment blanking period (see FIG. 30 (a)). Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input audio signal is converted into a digital audio signal by the A / D converter 9, and then the PCM encoder III 34 performs shuffling processing, error correction code, synchronization signal, ID signal addition, etc. Predetermined processing is performed. Further, the digital audio signal for one field period is P
It is divided into 3 to be multiplexed in the CM area.
After time axis compression and digital modulation, it is supplied to the switch B12.

Further, the signal generator 40 generates a signal having a single frequency, for example, a signal having a frequency corresponding to the gray level of the video signal.

Here, in FIG. 14, the recording signal of one field and the switches A11, B12, and C are shown.
41 shows a switching timing chart of 41. In the figure, gray is a signal of a single frequency corresponding to the gray level of the recorded FM signal. 14 (a) shows the output of the adder 13, FIG. 14 (b) shows the output of the signal generator 40, and FIGS. 14 (c), (d), and (e) show the switch A11, the switch B12, and the switch C41. A control signal output from the switch control circuit V 100 to the output of the adder 42 is shown in FIG. In the figure, switch A1
1. The control signal output to the switch B12 is the same as in the conventional example. Similarly to the conventional example, the switch C41 is ON when the control signal is "H" and OFF when the control signal is "L".
It will be. Based on the output of the sync separation circuit A4,
As shown in the figure, the switch control circuit V 100 provides a control signal so that a no-signal section is provided as in the conventional example and a signal of a single frequency corresponding to a gray level is inserted in the section of the gap B. And the switch A11, the switch B12, and the switch C41 are turned on and off according to the control signal. Then, after the outputs of the switch A11 and the switch B12 are added in the adder 13, the outputs of the switch C41 and the adder 13 are added in the adder 42, and as shown in FIG. Is generated in the recording signal to which the signal of the single frequency corresponding to is added.

Then, as in the conventional example, it is amplified by the recording amplifier 14 and recorded on the magnetic tape 1 by the video amplifiers 15a and 15b.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area including the gap A and the gap B to which a signal of a single frequency corresponding to the gray level is added are the same as those in the conventional example. Similarly, the reference signal generating circuit 1 is amplified by the head amplifiers 17a and 17b.
9 is switched by the head switching circuit 18 based on the HSW signal output from the FM demodulator 23 and the PC.
It is output to the M decoder II 36.

First, in the PCM decoder II 36, the PCM audio signal in the reproduced signal is detected and digital demodulated as in the conventional example, and thereafter, processing such as error detection, error correction, error correction and deshuffling processing is performed. , The original digital audio signal is restored. Then, the D / A converter 21 converts the analog audio signal and outputs the analog audio signal.

Next, in the FM demodulator 23, the section of the reproduced FM video signal and the gap B in which the signal corresponding to the gray level and the gap A is added to a part of the segment blanking period of the reproduced FM video signal. The containing PCM domain signal is FM demodulated.

Now, referring to FIG. 15, the VTR of this embodiment will be described.
The operation of the FM demodulator 23 will be described. FM
Since the demodulator 23 performs FM demodulation as in the first embodiment, the section of the gap B is demodulated into a gray level signal, and the signal immediately after the section of the gap B is also FM demodulated following the gray level signal. Therefore, as described in the conventional example, the demodulated waveform immediately after the section of the gap B does not fall outside the amplitude of the video signal. The S-sync immediately after the section of the gap B is FM-demodulated into a predetermined waveform as shown in FIG.

Then, in the PCM clip circuit 25, the output from the PCM area generation circuit 24 shown in FIG.
Based on the PCM area signal output from the PCM area generator 24 as shown in FIG. 15B, the reproduced video signal in which the signal below the black level of the PCM area is clipped as shown in FIG. Is clamped to a predetermined level at, and converted into a digital signal by the A / D converter 28. Further, the sync separation circuit C38 separates the sync signal from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit II39, based on the output of the sync separation circuit C38, the reproduction video signal is time-axis corrected,
After performing predetermined processing such as dropout compensation and absorption of the segment blanking section, the original luminance signal Y and the two color difference signals (RY) and (BY) are restored, and the synchronization signal is In addition, D / A converters 30a, 30b, 30c
At the output terminal 31 after being converted into analog data at
It is output by a, 31b, and 31c.

Therefore, the VTR of this embodiment is set to P when recording.
Since a signal of a single frequency corresponding to a gray level is inserted in the no-signal section of the CM area, S-sync is FM demodulated into a predetermined waveform and normal sync separation is performed in the sync separation circuit C38. The processing operation is performed well. In addition, since the signal falling below the black level in the segment blanking period of the reproduced signal can be reliably clipped, S-sync and H-sync are satisfactorily detected, and normal sync separation is performed in the sync separation circuit C38. Therefore, the control on a field-by-field basis in the reproduction signal processing circuit II39 also operates normally, and a stable reproduced image can be obtained.

Example 6. Next, a sixth embodiment will be described. The PCM audio signal inserted in the segment blanking period is as shown in FIG. As described in the second embodiment, the structure of the PCM audio signal to be inserted in the segment blanking period is provided with preamble and postamble sections at the beginning and end of the original digital audio data, and both sections are provided at the time of reproduction. A reference run-up signal is inserted when the clock is pulled in. The PCM audio signal section of the segment blanking period is configured by combining these three periods. Note that the run-up signal is selected to have a single frequency corresponding to the black level of the video signal.

FIG. 16 is a block diagram showing the structure of a VTR according to an embodiment of the present invention.
~ 9, 11-19, 21-23, 25-26, 28, 3
Since 0 to 31 are the same as those of the conventional example shown in FIG. 26, corresponding parts are designated by the same reference numerals, and detailed description thereof will be omitted. Further, since 33 and 36 to 39 are the same as the conventional example shown in FIG. 32, detailed description thereof will be omitted.

In the figure, 111 is a PCM encoder.
IV is the same as the conventional example, in which shuffling processing, an error correction code, a synchronizing signal and an ID signal are added to the digital voice, and the recorded digital voice signal of one field period is stored in the PCM area of the segment blanking period described above. As described above, the time base compression is performed, digital modulation is performed, and the result is output. At this time, although not described in the conventional example, the run-up signal is inserted into the preamble and the postamble as in the second embodiment. 110 is a switch A11 and a switch B1 based on the output of the sync separation circuit A4.
2 is a switch control circuit VI for controlling 2.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit II33. Also,
The sync signal is separated from the color TV signal in the sync separation circuit A4. The recording signal processing circuit II33 converts the input video signal into a TCI signal based on the output of the sync separation circuit A4, and then performs a predetermined process such as a process of a segment blanking period (see FIG. 30 (a)). Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input audio signal is converted into a digital audio signal by the A / D converter 9, and then the PCM encoder IV111.
Is output to. The PCM encoder IV111 inserts a reference run-up signal into the preamble and postamble during reproduction and clock pull-in in the same predetermined process as in the conventional example.

Here, as shown in the conventional example, when there is a no-signal section, at the time of reproduction, when FM demodulation is performed, a signal in the PCM area, that is, a mixed digital audio signal,
In addition, since FM demodulation is also applied to the non-signal section, the segment blanking data of the reproduced video signal immediately after the non-signal section is not FM demodulated to the original waveform (see FIG. 34). Therefore, as shown in FIG. 17 (b), a section obtained by adding the section of the gap B described in the conventional example to the section of the original postamble is set as the postamble, and a single level corresponding to the black level from the white level of the video signal is obtained. Insert the run-up signal of frequency.

Therefore, at the time of reproduction, when the reproduced FM video signal and the signal in the PCM area are FM-demodulated in the FM demodulator 23, the signal in the postamble section is FM-demodulated into the signal in the video signal amplitude and the postamble section. The segment blanking data immediately after is also FM demodulated to the original waveform.

Further, by changing the signal of a single frequency corresponding to the white level to the black level of the video signal to be inserted in the no-signal section to the run-up signal, a new signal corresponding to the white level to the black level of the video signal is newly added. It is not necessary to provide a circuit for generating a signal of one frequency in the recording signal processing system.

FIG. 18 shows a recording signal for one field and a switching timing chart of the switches A11 and B12. The output of the FM modulator 7 is shown in (a) of the figure, the output of the PCM encoder IV111 is shown in (b) of the figure, and the switch A11 and the switch B12 are shown in (c) and (d) of the figure.
The control signal output from the switch control circuit VI110 is shown in FIG. 7, and the output of the adder 13 is shown in FIG. Switch A
The switch 11 and the switch B12 are, for example, ON when the control signal is "H" and OFF when the control signal is "L". Based on the output of the sync separation circuit A4, the switch control circuit VI110 controls so as to provide a no-signal section, that is, a section of the gap A at the beginning of the PCM audio signal section and not to provide a no-signal section at the end, as shown in FIG. A signal is output, and the switch A11 and the switch B12 are turned on and off according to the control signal. The adder 13 adds the outputs of the switch A11 and the switch B12 to generate a recording signal as shown in FIG.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area are amplified by the head amplifiers 17a and 17b and output from the reference signal generation circuit 19 as in the conventional example. It is switched by the head switching circuit 18 based on the signal and output to the FM demodulator 23 and the PCM decoder II 36.

Similar to the conventional example, the PCM decoder II36 detects the PCM audio signal in the reproduced signal with reference to the run-up signals inserted in the preamble and the postamble, performs digital demodulation, and then performs error detection and error detection. Processing such as correction, error correction, and deshuffling processing is performed, and the D / A converter 21 converts the analog signal and outputs the analog signal.

In the FM demodulator 23, the reproduced FM video signal and P
The signal in the CM area is FM demodulated. Here, FIG.
As shown in (a), the signal in the PCM region, that is, the demodulation result of the digital audio data is larger than the amplitude of the video signal as in the conventional example, and although it is not known what the waveform is, the postamble including the no signal section is included. Since a run-up signal having a single frequency corresponding to the white level to the black level of the video signal is inserted in the signal, FM demodulation is performed on the signal within the video amplitude, and the segment blanking data immediately after the non-signal section is also the original. The waveform is FM demodulated.

Therefore, similarly to the fifth embodiment, the demodulation waveform of the signal immediately after the postamble does not drop to a level outside the video amplitude, and the S-sync is also FM demodulated to a predetermined waveform. Then, in the PCM clip circuit 25, the output of the PCM area generator 24 (see FIG. 19B).
Signals below the black level in the PCM region (see FIG. 19).
The reproduced video signal clipped (see (c)) is clamped to a predetermined level in the clamp circuit 26, and the A / D
It is converted into a digital signal in the converter 28. Further, the sync separation circuit C38 separates the sync signal from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit II39, based on the output of the sync separation circuit C38, the reproduction video signal is subjected to predetermined processing such as time axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y. And two color difference signals (R-
Y), (B-Y), the sync signal is added,
After being converted into analog data in the D / A converters 30a, 30b, 30c, output terminals 31a, 31b, 31
It is output by c.

Therefore, the VTR of this embodiment is set to P when recording.
Since a run-up signal of a single frequency corresponding to the white level to the black level of the video signal is inserted in the no signal section of the CM area, the S-sync has a predetermined waveform F as in the fifth embodiment.
Since M demodulation is performed and normal sync separation is performed in the sync separation circuit C38, the reproduced signal processing operation is favorably performed. Further, since S-sync and H-sync are satisfactorily detected, normal sync separation is performed in the sync separation circuit C38, and control in the field unit in the reproduction signal processing circuit II39 also operates normally and is stable. A reproduced image can be obtained.

Example 7. Next, a seventh embodiment will be described. FIG. 20 is a block diagram showing the configuration of the VTR of this embodiment. In FIG. 20, 1 to 4, 6 to 9, 11 to 19 and 2 are shown.
Since 1 to 23, 25 to 26, 28, and 30 to 31 are the same as those in the conventional example shown in FIG. 26, corresponding parts are designated by the same reference numerals and detailed description thereof will be omitted. Also 33, 36,
Since 38 to 39 are the same as the conventional example shown in FIG. 32, detailed description thereof will be omitted.

In FIG. 20, reference numeral 60 is a signal generator II for generating a signal of a single frequency, 61 is a switch D, 62 is an adder, and 120 is a PCM area generator IV.

Next, the operation of the recording system of this VTR will be described. Since the operation of the recording system is the same as that of the conventional example, it will be briefly described. The input color TV signal is converted into an A / D converter 3
It is converted into a digital video signal by a, 3b, and 3c and output to the recording signal processing circuit II33. Further, the sync separation circuit A4 separates the sync signal from the color TV signal. The recording signal processing circuit II33 converts the input video signal into a TCI signal based on the output of the sync separation circuit A4, and then performs a predetermined process such as a process of a segment blanking period (see FIG. 30 (a)). Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input audio signal is converted into a digital audio signal by the A / D converter 9, and then the PCM encoder III 3
4, a predetermined process such as a shuffling process, an error correction code, a sync signal, an ID signal is added. Further, the digital audio signal of one field period is divided into three for multiplexing in the PCM area provided in the segment blanking period of the recorded video signal, time-axis compression is performed, digital modulation is performed, and then the switch is performed. It is supplied to B12.

The control signal output from the switch control circuit 32 causes the switches A11 and B12 to
Is turned on and off, and a recording signal as shown in FIG. 33 (e) is generated in the adder 13 and recorded on the magnetic tape 1.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area including the gap A and the gap B are amplified by the head amplifiers 17a and 17b as in the conventional example, and the reference signal is generated. Circuit 1
Switching is performed by the head switching circuit 18 based on the HSW signal output from 9.

Further, the signal generator II60 generates a signal having a single frequency, for example, a signal having a single frequency corresponding to the gray level of the FM video signal, as in the first embodiment.

Now, referring to FIG. 21, the switch D61,
The operations of the adder 62 and the PCM area generator IV 120 will be described. FIG. 21 shows a reproduction signal of one field and a switching timing diagram of the switch D61. The switch D61 is turned on when the control signal is “H” and turned off when the control signal is “L” like the switches A11 and B12. It is a thing. A head switching circuit 18 is shown in FIG.
Output from the PCM area generator IV120 to the switch D61 in the same figure (b).
A control signal output to the adder 62 is shown in FIG. The PCM area generator IV120 detects the PCM area from the reproduced FM signal output from the head switching circuit 18, outputs the PCM area signal which becomes "H" in the PCM area, for example, to the PCM clip circuit 25. As shown, the control signal which becomes "H" in the section of the gap B is output to the switch D61. Switch D61
Performs ON and OFF operations according to the control signal. In addition, in the adder 62, the output of the head switching circuit 18 and the output of the switch D61 are added, and as shown in FIG. 7D, reproduction is performed in which a signal of a single gray level frequency is added to the section of the gap B. An FM signal is generated. This reproduced FM signal is sent to the FM demodulator 23 and the PCM decoder II3.
Output to 6.

In the PCM decoder II 36, the PCM audio signal in the reproduced signal is detected with reference to the run-up inserted in the preamble and the postamble, as in the conventional example.
After digital demodulation, processing such as error detection, error correction, error correction, and deshuffling is performed, and D /
The A converter 21 converts the analog audio signal and outputs the analog audio signal.

In the FM demodulator 23, the FM demodulator 23 is similar to the fifth embodiment.
Since demodulation is performed, the section of the gap B is demodulated into a gray level signal, and the signal immediately after the section of the gap B is also FM demodulated following the gray level signal.
As described in the conventional example, the demodulated waveform immediately after the section of the gap B does not fall to a level outside the video amplitude. In addition, S-sync immediately after the section of the gap B is shown in FIG.
As shown in FIG. 5 (a), FM demodulation is performed into a predetermined waveform.

Then, in the PCM clip circuit 25, the output from the PCM area generation circuit IV120 is shown in FIG.
FIG. 15 is based on the PCM domain signal as shown in (b).
As shown in (c), the reproduced video signal obtained by clipping the signal below the black level in the PCM area is clamped to a predetermined level in the clamp circuit 26 and converted into a digital signal in the A / D converter 28. Further, the sync separation circuit C38 separates the sync signal from the reproduced video signal output from the clamp circuit 26. Reproduction signal processing circuit II
In 39, based on the output of the sync separation circuit C38, the reproduction video signal is subjected to predetermined processing such as time-axis correction, dropout compensation, and segment blanking section absorption, and then the original luminance signal Y and two color differences. Signal (RY), (BY)
To the D / A converter 30 with the sync signal added.
After being converted into analog data at a, 30b, and 30c, the data is output from the output terminals 31a, 31b, and 31c.

Therefore, the VTR of this embodiment has the P
Since a signal of a single frequency corresponding to a gray level is inserted in the no signal section of the CM area to perform the FM demodulation operation of the reproduced FM video signal, the S-sync is performed as in the fifth embodiment.
Is subjected to FM demodulation into a predetermined waveform, and normal sync separation is performed in the sync separation circuit C38, so that the reproduced signal processing operation is favorably performed. In addition, S-sync and H-s
Since the sync detection is performed well, the sync separation circuit C
Normal sync separation is performed in 38, field-by-field control in the reproduction signal processing circuit II 39 also operates normally, and a stable reproduced image can be obtained.

Example 8. Next, Example 8 will be described. FIG. 22 is a block diagram showing the configuration of a VTR according to an embodiment of the present invention.
9, 11-19, 21-23, 25-26, 28, 30
26 to 31 are the same as those of the conventional example shown in FIG. 26, corresponding parts are designated by the same reference numerals, and detailed description thereof will be omitted.
Further, since 33 to 39 are the same as the conventional example shown in FIG. 32, detailed description thereof will be omitted.

Further, in the figure, 70 is a delay circuit for delaying the PCM region signal generated from the PCM region generator III 37 by a predetermined time, and 71 is an OR circuit.

Next, the operation of the recording signal processing system of this VTR will be described. The input color TV signal is converted into a digital video signal by the A / D converters 3a, 3b, 3c and output to the recording signal processing circuit II33. Also,
The sync signal is separated from the color TV signal in the sync separation circuit A4. The recording signal processing circuit II33 converts the input video signal into a TCI signal based on the output of the sync separation circuit A4, and then performs a predetermined process such as a process of a segment blanking period (see FIG. 30 (a)). Next, it is converted into an analog signal by the D / A converter 6, FM-modulated by the FM modulator 7, and then supplied to the switch A11. Similarly, the input audio signal is converted into a digital audio signal by the A / D converter 9, and then the PCM encoder III 3
4, a predetermined process such as a shuffling process, an error correction code, a sync signal, an ID signal is added. Further, the digital audio signal of one field period is divided into three for multiplexing in the PCM area provided in the segment blanking period of the recorded video signal, time-axis compression is performed, digital modulation is performed, and then the switch is performed. It is supplied to B12.

Then, according to the control signal output from the switch control circuit IV35, the switch A11 and the switch B1 are
2 performs ON and OFF operations, and a recording signal as shown in FIG. 33E is generated in the adder 13 and recorded on the magnetic tape 1.

Next, the operation of the reproducing system will be described. The reproduced FM video signal reproduced from the magnetic tape 1 via the rotary heads 16a and 16b and the signal in the PCM area including the gap A and the gap B are amplified by the head amplifiers 17a and 17b as in the conventional example, and the reference signal is generated. Circuit 1
Switching is performed by the head switching circuit 18 based on the HSW signal output from 9. The reproduction signal output from the head switching circuit 18 is sent to the FM demodulator 23 and the PCM.
It is output to the decoder II 36.

Similar to the conventional example, the PCM decoder II36 detects the PCM audio signal in the reproduced signal with reference to the run-up signals inserted in the preamble and the postamble, performs digital demodulation, and then performs error detection and error detection. Processing such as correction, error correction, and deshuffling processing is performed, and the D / A converter 21 converts the analog audio signal and outputs the analog audio signal.

Next, the operation of the FM demodulator 23 will be described. FIG. 23A shows the output waveform of the FM demodulator 23. Similar to the conventional example, by performing pulse count type FM demodulation on the gap B which is a non-signal section, the segment blanking data immediately after the PCM area has a waveform lower than the black level of the video signal (this period Like the example, referred to as Tb), from the end of the gap B to S-sy
If the period up to nc is sufficiently long, S-sync
Is demodulated into a predetermined waveform.

Next, the PCM area generator III 37 outputs the PCM area signal which becomes "H" in the PCM area of the reproduced video signal as shown in FIG. As shown in FIG. 23C, the delay circuit 70 delays the PCM area signal so that the PCM area signal includes the Tb period. The OR circuit 71 outputs the PCM area signal output from the delay circuit 70 and the PCM area signal output from the PCM area generator III 37 by the OR circuit 71.
The signal is generated to include the Tb period in addition to the PCM period period shown in (d).

The PCM clip circuit 25 shown in FIG.
On the basis of the PCM area signal indicated by, the image signal is clipped to the black level or higher as shown in FIG.

Then, the reproduced video signal in which the signal below the black level in the PCM area is clipped is clamped to a predetermined level in the clamp circuit 26 and converted into a digital signal in the A / D converter 28. Also, based on the output of the sync separation circuit C38, the sync signal is separated from the reproduced video signal output from the clamp circuit 26. In the reproduction signal processing circuit II39, based on the output of the sync separation circuit C38, the reproduction video signal is subjected to time axis correction, dropout compensation,
After a predetermined process such as absorption of the segment blanking portion is performed, the original luminance signal Y and two color difference signals (R-
Y), (B-Y), the sync signal is added,
After being converted into analog data in the D / A converters 30a, 30b, 30c, output terminals 31a, 31b, 3
It is output by 1c.

Therefore, in the VTR of this embodiment, when the period from the end of the non-signal section in the PCM region to S-sync is sufficient, that is, the S-sync by the FM demodulator 23.
In the case where sync is demodulated into a predetermined waveform, when clipping above the black level of the video signal, a period Tb in which the waveform falls below the black level of the video signal immediately after the no-signal section is added to the original PCM region. Since the region is clipped, S-sync and H-sync are detected well, and normal sync separation is performed in the sync separation circuit C38. Therefore, control in field units in the reproduction signal processing circuit II39 is performed. Also operates normally and a stable reproduced image can be obtained.

Example 9. Although a signal having a single frequency corresponding to the gray level of the video signal is inserted in the above-mentioned embodiment, which level corresponds to a signal having a frequency corresponding to the level from the black level to the white level of the video signal Signal, and need not be a single frequency signal.

Embodiment 10 In the above embodiment, a signal having a frequency corresponding to the level from the black level to the white level of the video signal is inserted in all the non-signal sections of the gap B, but the demodulated waveform in the Tb period is the video signal. If it is demodulated to a predetermined waveform between the white level and the black level, it is not necessary to insert it in all the non-signal sections of the gap B.

[Embodiment 11] In the above embodiment, a signal having a frequency corresponding to the white level to the black level of the video signal is inserted only in the non-signal section of the gap FM of the reproduced FM signal at the time of reproduction. If the waveform is demodulated into a predetermined waveform between the white level and the black level of the video signal, the signal of the above frequency may be inserted from the section after the postamble of the reproduced FM signal to the section of the gap B.

Example 12. Further, in the above embodiment, the VTR which records and reproduces the TCI signal of one field by dividing it into three segments has been described, but a multi-channel multi-segment VTR may be used, and a part of the vertical blanking period of the video signal may be used. , A PCM signal is recorded by providing a no-signal section at least with the vertical synchronizing signal, or by providing a no-signal section with at least the segment synchronizing signal in a part of the segment blanking period of the video signal.
If TR is used, the same effect is obtained.

Example 11. Also, not limited to the TCI signal,
It may be a composite signal such as an NTSC signal or a component signal such as a high-definition signal.
Even if it is incorporated into another video signal recording / reproducing apparatus, the same effect can be obtained.

[0162]

As described above, according to the present invention, at the time of recording, immediately after the PCM audio signal, that is, V- of the recorded video signal.
Since a signal of a single frequency corresponding to the white level to the black level of the video signal is recorded in the no-signal section immediately before sync,
During reproduction, the V-sync FM-demodulated into a predetermined waveform can be used for normal synchronization separation of the reproduced video signal without erroneously detecting the synchronous signal, and a stable reproduced image can be obtained.

Further, as described above, according to the present invention, the reference run-up signal is inserted from the white level to the black level of the video signal when it is inserted into the preamble and the postamble during recording and the clock is pulled in during reproduction. It is selected as a single frequency to be used, and is also inserted in the no-signal section immediately after the PCM audio signal at the time of recording, that is, immediately before V-sync of the recorded video signal. By FM-demodulated V-sync, the sync separation of the reproduced video signal can be normally performed, and a stable reproduced image can be obtained.

Further, as described above, according to the present invention, immediately after the PCM audio signal of the reproduced FM signal, that is,
Since a signal having a single frequency corresponding to the white level to the black level of the video signal is inserted in the no-signal section immediately before V-sync and the FM demodulation operation of the reproduced FM signal is performed, the sync signal is erroneously detected. Without this, the V-sync FM-demodulated into a predetermined waveform can normally perform the sync separation of the reproduced video signal, and a stable reproduced image can be obtained.

As described above, according to the present invention, in the reproduction, when the period from the end of the non-signal section of the PCM area to the V-sync of the reproduced video signal is sufficient, that is, the FM demodulator 23. When V-sync is demodulated to a predetermined waveform according to, when clipping above the black level of the video signal, a period Tb in which the waveform falls below the black level of the video signal immediately after the non-signal section is added to the original PCM region. Since the region is clipped, the V-sync FM-demodulated into a predetermined waveform can be obtained without erroneously detecting the sync signal.
As a result, the reproduced video signal can be normally separated in synchronization, and a stable reproduced image can be obtained.

Further, as described above, according to the present invention, immediately after the PCM audio signal multiplexed in the segment blanking period of each segment at the time of recording, that is, S of the recorded video signal is recorded.
Since a signal of a single frequency within the video signal band is recorded in the no-signal section immediately before -sync, the reproduced video signal can be reproduced by S-sync FM-demodulated into a predetermined waveform without erroneously detecting the sync signal. The sync separation can be performed normally, and a stable reproduced image can be obtained.

As described above, according to the present invention, the reference run-up signal is inserted from the white level to the black level of the video signal when it is inserted into the preamble and the postamble during recording and the clock is pulled in during reproduction. Since a single frequency to be selected is selected and the PCM audio signal multiplexed in each segment blanking period at the time of recording is also inserted into a no-signal section immediately before S-sync of the recorded video signal, a sync signal at the time of reproduction is selected. It is possible to normally perform the sync separation of the reproduced video signal by the S-sync FM-demodulated into a predetermined waveform without erroneously detecting the above, and to obtain a stable reproduced image.

As described above, according to the present invention, immediately after the PCM audio signal multiplexed in each segment blanking period of the reproduced FM signal during reproduction, that is, S-syn.
Since a signal of a single frequency corresponding to the white level to the black level of the video signal is inserted in the no-signal section immediately before c and the FM demodulation operation of the reproduced FM signal is performed, the sync signal may be erroneously detected. S-s FM demodulated into a predetermined waveform without
The sync can normally perform the sync separation of the reproduced video signal and can obtain a stable reproduced image.

As described above, according to the present invention, the PCs multiplexed in the segment blanking period of each segment.
When the period from the end of the no-signal section in the M region to S-sync is sufficient, that is, when the FM demodulator 23 demodulates S-sync into a predetermined waveform, the video signal is clipped to the black level or higher. At this time, since the region added with the period Tb, which is a waveform lower than the black level of the video signal immediately after the non-signal section, is clipped to the original PCM region, the synchronization signal is not erroneously detected and a predetermined waveform is obtained. By the FM-demodulated S-sync, the sync separation of the reproduced video signal can be normally performed, and a stable reproduced image can be obtained.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a video signal recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the first embodiment of the present invention.

FIG. 3 is a diagram for explaining the first embodiment of the present invention.

FIG. 4 is a diagram for explaining the first embodiment of the present invention.

FIG. 5 is a diagram for explaining a second embodiment of the present invention.

FIG. 6 is a block configuration diagram of a video signal recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 7 is a diagram for explaining a second embodiment of the present invention.

FIG. 8 is a diagram for explaining a second embodiment of the present invention.

FIG. 9 is a block configuration diagram of a video signal recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 10 is a diagram for explaining a third embodiment of the present invention.

FIG. 11 is a block configuration diagram of a video signal recording / reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 12 is a diagram for explaining a fourth embodiment of the present invention.

FIG. 13 is a block diagram of a video signal recording / reproducing device according to a fifth embodiment of the present invention.

FIG. 14 is a diagram for explaining a fifth embodiment of the present invention.

FIG. 15 is a diagram for explaining a fifth embodiment of the present invention.

FIG. 16 is a block configuration diagram of a video signal recording / reproducing apparatus according to a sixth embodiment of the present invention.

FIG. 17 is a diagram for explaining the sixth embodiment of the present invention.

FIG. 18 is a diagram for explaining the sixth embodiment of the present invention.

FIG. 19 is a diagram for explaining the sixth embodiment of the present invention.

FIG. 20 is a block diagram of a video signal recording / reproducing apparatus according to a seventh embodiment of the present invention.

FIG. 21 is a diagram for explaining the seventh embodiment of the present invention.

FIG. 22 is a block configuration diagram of a video signal recording / reproducing apparatus according to Example 8 of the present invention.

FIG. 23 is a diagram for explaining the eighth embodiment of the present invention.

FIG. 24 is a diagram showing a recording format of a VTR that records a TCI signal of one field by dividing it into three segments.

FIG. 25 is a diagram for explaining a conventional video signal recording / reproducing device.

FIG. 26 is a block diagram of a conventional video signal recording / reproducing device.

FIG. 27 is a diagram for explaining a conventional video signal recording / reproducing device.

FIG. 28 is a diagram for explaining a conventional video signal recording / reproducing device.

FIG. 29 is a diagram for explaining a conventional video signal recording / reproducing device.

[Fig. 30] A video signal of one field is divided into three segments, and P is set in a part of the segment blanking period.
It is a conceptual diagram of VTR which records a CM audio signal.

FIG. 31 is a diagram for explaining a conventional video signal recording / reproducing device.

FIG. 32 is a block diagram of a conventional video signal recording / reproducing apparatus.

FIG. 33 is a diagram for explaining a conventional video signal recording / reproducing device.

FIG. 34 is a diagram for explaining a conventional video signal recording / reproducing device.

[Explanation of symbols]

 11 switch A 12 switch B 13 adder 24 PCM area generator 25 PCM clip circuit 37 PCM area generation III 40 signal generator 41 switch C 42 adder 43 switch control circuit II 50 PCM encoder II 51 switch control circuit III 60 signal generation Unit II 61 Switch D 62 Adder 63 PCM region generator II 70 Delay circuit 71 OR circuit 100 Switch control circuit V 111 PCM encoder IV 120 PCM region generator IV

[Procedure amendment]

[Submission date] March 16, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Next, the reproduction signal processing system will be described. 1
7a and 17b are head amplifiers, 18 is a head amplifier 17 based on a head switching signal (hereinafter referred to as HSW signal) output from a reference signal generating circuit 19 described later.
a head switching circuit for switching the outputs of a and 17b, 1
Reference numeral 9 is a reference signal generation circuit for outputting the HSW signal, which serves as a reference signal at the time of reproduction, to the head switching circuit, and 20 is a reproduction audio signal in the PCM area in the reproduction signal output from the head switching circuit 18 as digital data. conversion, converts the reproduction digital audio signal by performing digital demodulation, time axis expansion, error detection, error correction, a PCM decoder for positive error Osamu, and deshuffling process and the like. Further, 24 is P detected in the PCM decoder.
A PCM clip circuit 25, which will be described later, outputs a signal indicating the CM area.
It is a PCM domain signal generator for outputting to. 21 is a D for converting a reproduced digital audio signal into a reproduced analog audio signal
An A / A converter 22 is an output terminal for an audio signal.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideki Kaneko 1 Baba Institute, Nagaokakyo City, Kyoto Prefecture Mitsubishi Electric Corporation Kyoto Factory

Claims (8)

[Claims] 1. A video signal recording / reproducing apparatus for recording / reproducing a digital audio signal of one field period in a part of a vertical blanking period of an FM-modulated recording video signal at the time of recording by providing a no signal section before and after the digital audio signal. During recording, a video signal recording / reproducing apparatus characterized in that a signal having a frequency corresponding to a white level to a black level of the recording FM signal is inserted in a no-signal section immediately after the digital audio signal of the recording signal. 2. A video signal recording / reproducing apparatus for recording / reproducing a digital audio signal of one field period in a part of a vertical blanking period of a recorded video signal FM-modulated at the time of recording, in the section of the digital audio signal of the recording signal. The frequency of the postamble signal inserted immediately after is recorded FM
A video signal recording / reproducing apparatus characterized in that a signal of a corresponding frequency is inserted between a white level and a black level of the signal. 3. A video signal recording / reproducing apparatus for recording / reproducing a digital audio signal of one field period in a part of a vertical blanking period of an FM-modulated recording video signal at the time of recording by providing a no signal section before and after the digital audio signal. At the time of reproduction, a reproduction FM is performed in a no-signal section immediately after the digital audio signal of the reproduction signal.
A video signal recording / reproducing apparatus characterized in that a signal of a corresponding frequency is inserted between a white level and a black level of the signal. 4. A video signal recording for recording / reproducing a digital audio signal of one field period in a part of a vertical blanking period (PCM area) of a recorded video signal FM-modulated at the time of recording by providing a no signal section before and after it. In the playback device,
PCM area detecting means for detecting the PCM area in which the digital audio signal is recorded from the reproduced signal during reproduction,
PCM clip signal generating means for generating a PCM clip signal based on the output of the PCM area detecting means;
A video signal recording / reproducing apparatus comprising at least video signal clipping means for clipping an FM demodulated signal based on a CM clip signal to a signal having a predetermined level or less. 5. A digital audio signal of one field period is divided into a plurality of blocks in a part of a plurality of segment blanking periods of a recording video signal FM-modulated at the time of recording, and a no signal section is provided before and after the recording. In a video signal recording / reproducing apparatus for reproducing, at the time of recording, a signal having a frequency corresponding to between the white level and the black level of the recorded FM signal is inserted in a no signal section immediately after the digital audio signal of the recorded signal. Video signal recording / reproducing device. 6. A video signal recording / reproducing apparatus for dividing a digital audio signal of one field period into a plurality of blocks in a part of a plurality of segment blanking periods of an FM-modulated recording video signal at the time of recording and recording / reproducing. A video signal recording / reproducing apparatus characterized in that the frequency of the postamble signal inserted immediately after the section of the digital audio signal of the recording signal is inserted between the white level and the black level of the recording FM signal. .. 7. A digital audio signal of one field period is divided into a plurality of blocks in a part of a plurality of segment blanking periods of a recording video signal FM-modulated at the time of recording, and a no-signal section is provided before and after the recording. In a video signal recording / reproducing apparatus for reproducing, at the time of reproduction, a signal having a frequency corresponding to between the white level and the black level of the reproduced FM signal is inserted in a no-signal section immediately after the digital audio signal of the reproduced signal. Video signal recording / reproducing device. 8. A digital audio signal of one field period is divided into a plurality of blocks in a part (PCM area) of a plurality of segment blanking periods of a recording video signal FM-modulated at the time of recording, and there is no signal section before and after that. In a video signal recording / reproducing apparatus for recording and reproducing by providing a PC, a PC in which the digital audio signal is recorded from the reproduced signal during reproduction.
PCM area detecting means for detecting the M area, PCM clip signal generating means for generating a PCM clip signal based on the output of the PCM area detecting means, and an FM demodulation signal based on the PCM clip signal to a predetermined level A video signal recording / reproducing apparatus comprising at least video signal clipping means for clipping the following signals.