JPH0832996A - Magnetic recording and reproducing devices for video signal - Google Patents

Abstract

PURPOSE:To provide a VTR Which accurately demodulates an EDTV signal by generating a burst signal synchronized with the burst signal related to a video signal and a reference signal having the same frequency and interposing the reference signal to the luminance signal to record it in the recording system. CONSTITUTION:A counter circuit 3 specifies the period, when the emphasis signal related to an EDTV signal aa is interposed, to supply a signal 3a to a YC separation means 1, and the luminance signal and the color signal are separated from each other. A first recording signal 1a consists of the luminance signal related to a main signal and the emphasis signal, and a second recording signal 1b consists of the color signal related to the main signal. A 3.58MHz reference signal 21a of a single wave synchronized with the phase of the burst signal related to the signal 1b is generated and is supplied to a gate circuit 22. A signal 3b where one line of the vertical blanking period is specified is supplied from the circuit 3 to the circuit 22, and the signal 21a is supplied to an inserting means 20 only in this period. The means 20 adds the recording signal 1a and the signal from the circuit 22 to output a signal 20a to an LPF 4, and the recording signal 1b is supplied to a BPF 5 and is recorded on a magnetic tape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal magnetic recording device and a video signal magnetic reproducing device.

[0002]

2. Description of the Related Art In recent years, EDTV signals for transmitting high-definition images while maintaining compatibility with conventional video signals are being adopted. This EDTV signal is composed of a main signal portion and a reinforcement signal portion having a high frequency component, and the reinforcement signal is modulated by a 3.58 MHz subcarrier in the same manner as a color signal.

Since such a reinforcement signal has no vertical correlation, if the YC separation means for separating the video signal into the luminance signal and the chrominance signal performs the separation using the vertical correlation, it becomes an interference signal. . Also, the luminance signal is FM-modulated and recorded,
When the color signal is converted to the low frequency range and recorded, the frequency characteristics, phase characteristics, relative time error, and relative jitter amount of the luminance signal system and the color signal system are different, so the reinforcement signal is separated into both systems. Interference will occur if recorded and played back.

Therefore, in order to solve such a problem, the applicant of the present invention has previously proposed a magnetic recording / reproducing apparatus for recording all reinforcing signals by a luminance signal system as 1992 Patent Application No. 30145. This proposal will be described with reference to FIGS.

FIG. 6 is a block diagram of a recording system of a conventional video signal magnetic recording / reproducing apparatus. In the figure, the EDTV signal aa is supplied to the YC separation means 1 and the synchronization separation means 2 from a transmission line (not shown). The horizontal synchronizing signal separated by the synchronizing separating means 2 is counted by the counter circuit 3 from the start of the vertical synchronizing signal, and the period in which the reinforcing signal related to the EDTV signal aa is inserted is specified. Then, the signal 3a representing the period is supplied to the YC separation means 1, where the luminance signal and the color signal are separated. In this separation, the main signal is separated into a luminance signal and a chrominance signal, but the reinforcement signal is output to the luminance signal system. That is, the first recording signal 1a is composed of a luminance signal related to the main signal and the reinforcement signal, while the second recording signal 2a is composed of a color signal related to the main signal.

After the high frequency component of the first recording signal 1a is emphasized by the emphasis means 6 through the low pass filter 4, the FM modulation means 8 is passed through a limiter (not shown) to prevent so-called inversion phenomenon. Is supplied to. And
The FM modulating means 8 obtains an unmodulated FM signal having a relatively high frequency component and supplies it to one input of the adding means 9.
On the other hand, the second recording signal 2a is supplied to the low-frequency converting means 7 via the bandpass filter 5, and here, for example, 62
After being converted into a low-frequency converted signal having a center frequency of 9 KHz, it is supplied to the other input of the adding means 9.

Then, a signal obtained by frequency-multiplexing the non-modulated FM signal and the low-frequency converted signal by the adding means 9 is recorded on the magnetic tape T via the magnetic head H.

Next, the reproducing system will be described with reference to FIG. The signal reproduced from the magnetic tape T via the magnetic head H is a high-pass filter 10 and a low-pass filter 14.
And is supplied to the FM demodulation means 11 and the high frequency conversion means 15 via. The signal demodulated by the FM demodulation means 11 is supplied to the de-emphasis means 12 having a complementary relationship with the emphasis means 6. After the high frequency component is attenuated by the de-emphasis means 12, the first reproduction signal 13a corresponding to the first recording signal 1a is supplied to one input of the adding means 17 through the low pass filter 13. There is. In addition, the high frequency conversion means 15 converts the signal converted into the low frequency band into the original frequency band, and then the second recording signal 1b obtained through the band pass filter 16 is obtained.
Is supplied to the other input of the adding means 17. Then, the adding means 17 adds the first and second reproduction signals 13a and 16a to obtain the reproduction video signal bb.

[0009]

By the way, in an EDTV compatible TV, the reinforcement signal is demodulated with reference to the phase of the burst signal as in the case of the color signal. The main part of this demodulation will be described with reference to FIG. 8. The reinforcement signal cc separated from the reproduced video signal bb is supplied to the demodulation means 18. Also, the burst signal dd separated from the reproduced video signal bb
Is supplied to the 3.58 MHz generating means 19, where a single wave of 3.58 MHz synchronized with the burst signal dd is generated and supplied to the demodulating means 18. And the demodulation means 1
Reference numeral 8 demodulates the reinforcement signal cc using the output signal of the 3.58 MHz generating means 19.

However, if the relative time (phase) between the reinforcement signal and the burst signal does not match, a demodulation error will occur. Here, since one cycle of the burst signal of 3.58 MHz is 280 ns, approximately 0.8 ns / deg (= 28
0/360). On the other hand, in a home VTR, it is known that there is a time error of about ± 50 ns between the luminance signal system and the color signal system.

Therefore, in the conventional magnetic recording / reproducing apparatus, if the reinforcement signal is recorded / reproduced by using the luminance signal system and the burst signal is recorded / reproduced by using the color signal system together with the color signal as described above, the reinforcement signal and the burst ± 6 between signal
There is a problem in that a phase error of 2.5 ° is generated, and accurate demodulation cannot be performed, resulting in interference on the screen.

Therefore, it is an object of the present invention to provide a magnetic recording / reproducing apparatus which solves the above-mentioned interference.

[0013]

The present invention provides the following configurations in order to solve the above problems.

A first aspect of the invention is a video signal for recording on a magnetic recording medium a video signal comprising a main screen signal and a reinforcement signal having a high frequency component of the main screen, which is modulated by a color subcarrier associated with the main screen signal. In a magnetic recording device, YC separation means for separating the main screen signal into a luminance signal and a chrominance signal, insertion means for inserting into the luminance signal a reference signal synchronized with a color subcarrier relating to the main screen signal, Provided is a video signal magnetic recording device having a recording means for multiplexing a signal obtained by subjecting an output signal of the inserting means to a predetermined processing and a signal obtained by subjecting the color signal to a predetermined processing to the magnetic recording medium. It is a thing.

A second invention is a video signal reproducing apparatus for reproducing the magnetic recording medium according to the first invention, wherein the signal reproduced from the magnetic recording medium is subjected to a predetermined reproducing process to obtain the above-mentioned reinforcement signal and the above-mentioned signal. Means for reproducing the luminance signal, means for reproducing the color signal by subjecting the signal reproduced from the magnetic recording medium to a predetermined reproduction process, and the reference signal relating to the reproduced luminance signal and the reproduced reference signal. Phase difference detecting means for generating a control signal obtained by detecting a phase difference between the color subcarrier relating to the color signal, and the reproduced reinforcement signal and the luminance signal reproduced based on the control signal. A video signal magnetic reproducing apparatus having a variable delay means for delaying either one of a color signal and a color signal.

[0016]

1 is a block diagram for explaining the main part of a recording system of a video signal magnetic recording / reproducing apparatus according to the present invention, FIG.
1 is a timing chart for explaining FIG. 1, FIG. 3 is a block diagram for explaining a main part of a reproducing system of a video signal magnetic recording / reproducing apparatus according to the present invention, and FIG. 4 is a timing chart for explaining FIG. FIG. 5 is a characteristic diagram for explaining the corrector. Embodiments will be described below with reference to the drawings. It should be noted that the same components as those in FIGS.

The outline of the present invention is to generate a reference signal having the same frequency as a burst signal synchronized with a burst signal relating to a video signal in a recording system, and insert the reference signal into a luminance signal for recording. Further, the phase difference between the reference signal reproduced by the reproducing system and the reproduced burst signal is detected, and the phase of the second reproduced signal and the phase of the first reproduced signal are matched based on this. .

First, the recording system will be described with reference to FIGS. The recording system according to the present embodiment is obtained by replacing the portion surrounded by the dotted line of the conventional video signal magnetic recording / reproducing apparatus shown in FIG. 6 with the configuration shown in FIG.

In FIG. 1, the EDT is connected from a transmission line (not shown).
The V signal aa (shown in FIG. 2A) is supplied to the YC separation means 1 and the synchronization separation means 2. The horizontal synchronizing signal separated by the synchronizing separating means 2 is counted by the counter circuit 3 from the start of the vertical synchronizing signal, and the period in which the reinforcing signal related to the EDTV signal aa is inserted is specified. Then, the signal 3a representing the period is supplied to the YC separation means 1, where the luminance signal and the color signal are separated. In this separation, the main signal is separated into a luminance signal and a chrominance signal, but the reinforcement signal is output to the luminance signal system. That is, the first recording signal 1a is composed of a luminance signal related to the main signal and the reinforcement signal, while the second recording signal 2a is composed of a color signal related to the main signal.

Then, the second recording signal 2a (FIG. 2 (E))
3.58 synchronized with the phase of the burst signal according to FIG.
A reference signal 21a (shown in FIG. 2B) which is a single wave of MHz is generated and supplied to the gate circuit 22. Further, the gate circuit 22 is supplied with the signal 3b specifying one line of the vertical blanking period from the counter circuit 3, and supplies the reference signal 21a to the inserting means 20 only during the period.
Then, the inserting means 20 adds the first recording signal 1a and the output signal of the gate circuit 22 to generate the output signal 20a.

A reference signal 21a representing the phase of the burst signal is superimposed on the output signal 20a thus obtained, and the output signal 20a is replaced by the low-pass filter shown in FIG. 6 in place of the first recording signal 1a. 4 and the second recording signal 1b is supplied to the bandpass filter 5 and recorded on the magnetic tape T as described in the related art.

Next, the reproducing system will be described with reference to FIGS. 3 and 4. The reproducing system according to the present embodiment is obtained by replacing the portion surrounded by the dotted line of the conventional video signal magnetic recording / reproducing apparatus shown in FIG. 7 with the configuration shown in FIG.

In FIG. 3, the low-pass filter 13 shown in FIG. 7 supplies the first reproduction signal 13a (shown in FIG. 4A) to the sync separation circuit 30 and the gate circuit 32. The sync separation circuit 30 separates the horizontal sync signal from the first reproduction signal 13a and supplies it to the counter circuit 31. The counter circuit 31 counts the horizontal synchronizing signal from the start of the vertical synchronizing signal, specifies the line in which the reference signal 21a is inserted at the time of recording, and generates the signal 31a (illustrated in FIG. 4C). Then, the gate circuit 32 supplies the reproduced reference signal related to the first reproduced signal 13a using the signal 31a to one input of the phase difference detection means 33.

The second reproduction signal 16a (shown in FIG. 4B) from the bandpass filter 16 shown in FIG. 7 is transmitted through the variable delay means 34 to the 3.58 MHz generating means 35.
Where a single wave of 3.58 MHz synchronized with the phase of the burst signal related to the second reproduction signal 16a (see FIG.
(Illustrated in (D)) is generated and supplied to the other input of the phase difference detection means 33. Then, the phase difference detecting means 33 controls the control signal 3 corresponding to the time difference between the luminance signal system and the color signal system.
3a is generated by obtaining the phase difference between the output signals of the gate circuits 32 and 33. Then, the delay time of the variable delay means 34 is controlled using the control signal 33a, and the third reproduction signal 34 obtained by delaying the second reproduction signal 16a by a predetermined time.
a (illustrated in FIG. 4 (E)) is supplied to the adding means 17,
And a reproduced video signal bb is generated by adding the reproduced signal 13a.

In this way, the reinforcement signal is recorded / reproduced together with the reference signal using the luminance signal system, and the burst signal is recorded / reproduced together with the color signal using the color signal system to detect the phase difference between the reference signal and the burst signal. Then, based on this, since one reproduction signal was delayed to match the other reproduction signal,
Accurate demodulation can be performed when the EDTV signal is recorded and reproduced, and the image quality can be improved.

(Other Embodiments) Since the level of the reference signal changes depending on the transmission characteristics of the recording / reproducing system, a corrector may be inserted at point A in FIG. 3 to correct this. here,
The transmission characteristic is -3d at 3.58MHz as shown in FIG.
When the characteristic of b is assumed, the characteristic of the compensator may be the characteristic shown in FIG.
The characteristic of the second input signal can be made flat as shown in FIG.

Further, although the variable delay means 34 in FIG. 3 is provided in the color signal system, it suffices if the time difference (phase difference) between the luminance signal system and the color signal system can be eliminated. Of course, it may be provided in the system. However, since the band of the color signal is narrower than the band of the luminance signal, it is possible to simplify the configuration by providing the variable delay means 34 in the color signal system.

Further, it goes without saying that the variable delay means 34 may also serve as a time base collector for correcting the jitter of the reproduced signal.

Since the reference signal is inserted in the luminance signal system in order to obtain the time difference between the luminance signal system and the color signal system at the time of reproduction, the color subcarrier and the frequency or phase recorded in the color signal system. Do not have to match, and a certain phase relationship is sufficient. That is, it is sufficient if the reference signal is synchronized with the color subcarrier.

The input signal of the 3.58 MHz generating means 21 need not be the second recording signal 1b but may be the EDTV signal aa.

[0031]

As described above, according to the configuration of the present invention,
Particularly, since the reference signal synchronized with the color subcarrier relating to the main screen signal is inserted into the luminance signal, it is possible to multiplex and transmit the reference signal serving as the phase reference when demodulating the reinforcement signal to the luminance signal. There is an effect that can be.

As described above, according to the configuration of the present invention, in particular, the control obtained by detecting the phase difference between the reference signal relating to the reproduced luminance signal and the color subcarrier relating to the reproduced color signal. Since it has a phase difference detection means for generating a signal, and a variable delay means for delaying any one of the reproduced reinforcement signal and the reproduced luminance signal and the reproduced color signal based on the control signal, The phase of the reinforcement signal can be matched with the phase of the subcarrier of the color signal, and as a result, there is an effect that a phase error can be eliminated at the time of demodulation of the reinforcement signal and the image quality can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining a main part of a recording system of a video signal magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a timing chart for explaining FIG.

FIG. 3 is a block diagram for explaining a main part of a reproducing system of the video signal magnetic recording / reproducing apparatus according to the present invention.

FIG. 4 is a timing chart for explaining FIG.

FIG. 5 is a characteristic diagram for explaining a corrector.

FIG. 6 is a block diagram of a recording system of a conventional video signal magnetic recording / reproducing apparatus.

FIG. 7 is a block diagram of a reproducing system of a conventional video signal magnetic recording / reproducing apparatus.

FIG. 8 is a block diagram for explaining demodulation of a reinforcement signal in a TV compatible with EDTV.

[Explanation of symbols]

 1 YC separation means 17 Addition means (recording means) 20 Insertion means 33 Phase difference detection means 34 Variable delay means 21a Reference signal 33a Control signal aa Video signal T Magnetic tape (magnetic recording medium) H Magnetic head (recording means)

Claims (2)

[Claims] 1. A video signal magnetic recording device for recording on a magnetic recording medium a video signal comprising a main screen signal and a reinforcement signal having a high frequency component of the main screen, which is modulated by a color subcarrier according to the main screen signal. In YC separating means for separating the main screen signal into a luminance signal and a chrominance signal, an inserting means for inserting into the luminance signal a reference signal synchronized with a color subcarrier relating to the main screen signal, A video signal magnetic recording apparatus comprising: a recording unit that multiplexes a signal obtained by subjecting an output signal to a prescribed process and a signal obtained by subjecting a color signal to a prescribed process to the magnetic recording medium. 2. A video signal magnetic reproducing apparatus for reproducing the magnetic recording medium according to claim 1, wherein the signal reproduced from the magnetic recording medium is subjected to a predetermined reproducing process to obtain the reinforcing signal and the luminance signal. For reproducing the color signal by subjecting the signal reproduced from the magnetic recording medium to a predetermined reproduction process, and the reference signal related to the reproduced luminance signal and the reproduced color signal. Phase difference detecting means for generating a control signal obtained by detecting a phase difference with the color subcarrier according to, and the reproduced reinforcement signal and the luminance signal and the reproduced color signal based on the control signal. And a video signal magnetic reproducing apparatus having a variable delay means for delaying one of the two.