JPS5836874B2 - Method for recording and reproducing color video signals and recording device thereof - Google Patents

Description

[Detailed Description of the Invention] For example, when recording a luminance signal (monochrome video signal) on a magnetic tape in a VTR (magnetic recording/reproducing device), the following method can significantly increase the recording amount. can.

That is, as shown in FIG. 1, rotating magnetic heads 1 and 2 are provided with an angular spacing of 180 degrees from each other, and are rotated at a rate of 30 times per second, and a magnetic tape 3 is rotated approximately 180 degrees along a tape guide drum 4. run diagonally over an angular range of

Further, in this case, as shown in FIG. 2, the width directions, that is, the azimuth angles of the operating gaps g1 and g2 of the heads 1 and 2 are made different from each other.

Then, the brightness signal is converted into an FM signal that occupies the Takagi side of the recordable band, and this FM brightness signal is supplied to the heads 1 and 2.

Therefore, according to such a recording method, one field of the luminance signal is recorded diagonally on the tape 3 as one magnetic track 5, as shown in FIG.

Therefore, let us consider a case where such a recorded pattern is reproduced using a magnetic head similar to that described above.

Then, since the azimuth angle is different between the playback head for track 5A and the playback head for track 5B, and the FM brightness signal is recorded on the Takagi side, crosstalk between tracks due to azimuth loss will not occur.<FM brightness Can reproduce the signal.

Also, even if some crosstalk occurs between tracks,
Since the luminance signal is an FM signal, its crosstalk is suppressed by the limiting action of the limiter in the reproduction system.
Therefore, an FM luminance signal without inter-track crosstalk can be obtained.

In this way, since inter-track crosstalk does not occur in the reproduced FM luminance signal, the width of the guard band between adjacent tracks 5A and 5B is narrowed during recording.
Alternatively, as shown in FIG. 3, the FM luminance signal can be recorded so that there is no guard band, and furthermore, the adjacent tracks 5A and 5B partially overlap, so that the amount of recording can be greatly increased.

On the other hand, in order to magnetically record a color video signal, the luminance signal is generally converted into an FM luminance signal, and the carrier color signal is frequency-converted to the lower frequency side of the FM luminance signal, and the frequency-converted carrier color signal is The sum signal of the FM luminance signal and the FM luminance signal is magnetically recorded.

Therefore, when recording the luminance signal using the recording method shown in FIGS. 1 to 3, it is conceivable to frequency-convert the carrier color signal to a lower frequency band, add it to the FM luminance signal, and record the signal simultaneously.

However, simply recording in this way will not cause inter-track crosstalk for the luminance signal due to the azimuth loss of the reproducing head during playback, but since the carrier chrominance signal has a low frequency band, the carrier chrominance signal of the adjacent magnetic track will not occur. In contrast, the azimuth loss of the reproducing head is small, and therefore inter-track crosstalk occurs in the carrier color signal.

The present invention takes these points into account and provides a recording device that can significantly increase the recording amount of color video signals and that does not cause inter-track crosstalk in the carrier color signals during playback. .

For this reason, in the present invention, the luminance signal is converted to an FM signal so as to occupy the high frequency side of the recordable band, the carrier color signal is frequency-converted to the lower frequency side of the FM luminance signal, and the frequency-converted carrier color A multiplexed signal of the signal and the FM luminance signal is recorded, and in this case, the carrier frequency of the carrier color signal is interleaved in every other magnetic track 5A and every other remaining magnetic track 5B. Create a relationship.

Further, in this case, the alternating signal for low-frequency conversion of the carrier color signal is synchronized in phase with the synchronization pulse of the luminance signal.

That is, as shown in the frequency spectrum of the recording signal in FIG. 4, in every other vertical period Ta (FIG. 4A), F
M luminance signal Sy and carrier frequency f.

The multiplexed signal with the carrier color signal Sc of a is sent to the magnetic track 5A.
On the other hand, in every other remaining vertical period Tb (FIG. 4B), the FM luminance signal Sy and the carrier frequency f are recorded.

The multiplexed signal with the carrier color signal Sc of b is transferred to the magnetic track 5B.
Record as.

And in this case, This is the case.

That is, the NTSC color video signal is supplied to the low-pass filter 2 through the terminal 11, and the luminance signal is extracted.
This luminance signal is supplied to the FM modulation circuit 13 to become an FM luminance signal Sy, and this signal Sy is passed through the high-pass filter 4.
After removing unnecessary signal components, the signal is supplied to the adder circuit 15.

Further, oscillation circuits 16 and 17 are provided, and from the oscillation circuit 1 16 a frequency (f8 - fh) (for example, f83.5
sMHZ) is taken out, and this oscillation signal is supplied to one contact of the switch circuit 18, and the oscillation circuit 17 outputs the frequency (f5+, fh).
The oscillation signal is taken out, and this oscillation signal is supplied to the other contact of the switch circuit 18.

Further, the color video signal from the terminal 11 is supplied to a vertical synchronization separation circuit 21 to extract a vertical synchronization pulse, and this pulse is supplied to a flip-flop circuit 22, from which it is divided into one vertical period as shown in FIG. 8A. An inverted pulse Pa is generated, and this pulse Pa is applied to the switch circuit 18.
is supplied as its control signal.

Therefore, from the switch circuit 18, as shown in FIG. 8B, a signal at the frequency (f5--li-fh) and a signal at the frequency (fs+7th) are alternately taken out every vertical period.

The oscillation signal from this switch circuit 18 is then supplied to a frequency converter 23.

A variable frequency oscillation circuit 25 is also provided, and this For example, the reference frequency is f.

--H (foa+feb) -44fh (approximately 6
An oscillation signal of 93 KHz) is taken out, and this oscillation signal is supplied to a down-down circuit 26 to produce a signal with a frequency of one frequency, that is, a frequency fh. The color video signal is supplied to the horizontal synchronization separation circuit 28 to extract the horizontal synchronization pulse, and this pulse is sent to the comparison circuit 2.
7.

Then, in the comparator circuit 27, the signal from the down-down circuit 26 and the horizontal synchronizing pulse from the separation circuit 28 are compared in phase and frequency, and the comparison output is sent to the variable frequency oscillation circuit 25.
is supplied as its control signal.

In this way, an oscillation signal having a frequency f=44fhC, which is locked to a frequency 44 times the horizontal frequency fh, is extracted from the oscillation circuit 25.

This oscillation signal is then supplied to the converter 23.

Therefore, from the converter 23, an alternating signal with a frequency (fo+f, 1l-fh) and a frequency (fo+f5+7) which are in phase synchronization with the horizontal synchronizing pulse and are interleaved with each other as shown in FIG.
fh)4 alternating signals are obtained alternately every vertical period.

The alternating signal from the converter 23 is supplied to the frequency converter 31, and the color video signal from the terminal 11 is supplied to the C-shaped comb filter 32 to provide the carrier color signal S.
s (carrier frequency f,) is extracted, and this carrier color signal S
s is supplied to the converter 31.

Therefore, the converter 31 outputs the carrier color signal Sc that has been low-frequency converted, that is, the carrier frequency is f, as shown in FIG. 8D.

a=fc 4', a carrier color signal Sc of h, and a carrier frequency of f.

A carrier color signal Sc of b=fo+7fh is obtained alternately every vertical period.

The carrier color signal Sc from the converter 31 is supplied to the adder circuit 15 after unnecessary signal components are removed by a low-pass filter 33 .

In this way, from the adder circuit 15, a multiplexed signal with the frequency spectrum shown in FIG. 4A and a multiplexed signal with the frequency spectrum shown in FIG. 4B are obtained alternately every vertical period.

The multiplexed signal from the adder circuit 15 is supplied to the heads 1 and 2 through the recording amplifier 34, and one field thereof is recorded as one magnetic track 5 on the tape 3 in the pattern shown in FIG.

In this case, the pulse Pa (FIG. 8A) from the flip-flop circuit 22 is supplied to the servo circuit 35 to perform servo control during recording, and the pulse Pa is supplied to the magnetic head 36, as shown in FIG. Like, tape 3
is recorded as a magnetic track 6 on one side of the .

When track 5 recorded in this manner is reproduced by heads 1 and 2, as mentioned above, the FM luminance signal sy occupies a high frequency band, so it is possible to extract it without causing inter-track crosstalk due to azimuth loss. can.

However, since the carrier color signal Sc has a low occupied frequency band,
A reduction in inter-track crosstalk due to azimuth loss such as in the FM luminance signal Sy cannot be expected, and therefore, as shown in FIG. 5A, the carrier frequency f is changed from the track 5A.

During the vertical period Ta during which the carrier color signal Sc of a is being reproduced, the carrier frequency f is transmitted from the adjacent track 5B.

During the vertical period Tb, the carrier color signal Sc of carrier frequency feb is simultaneously reproduced as the crosstalk component Sk, and as shown in FIG. 5B, the carrier color signal Sc of carrier frequency feb is reproduced from track 5B. , the carrier frequency f from the adjacent track 5A.

The carrier color signal (shown by the dotted line) of a is simultaneously reproduced as the crosstalk signal Sk.

However, in this case, the carrier frequency of the carrier color signal Sc in the adjacent magnetic tracks 5A and 5B is f.

a, feb and are interleaved with each other, so when the carrier color signal Sc is frequency converted to the carrier color signal Ss of the original carrier frequency f, then this carrier color signal S
The crosstalk component Sk included in s becomes a carrier frequency interleaved with the signal Ss.

If the crosstalk component Sk is interleaved, the crosstalk component Sk can be removed by supplying the carrier color signal Ss to, for example, a C-comb filter.

FIG. 7 shows an example of such a reproduction system, which will be explained below.

That is, as the head 36 reproduces the track 6, the head 36 outputs a pulse Pa as shown in FIG. 8E.
A differential pulse Pe of
Head 1, so that the relationship with 5B is the same as during recording.
Tracking servo is performed for the second track 5.

In this way, from the heads 1 and 2, the multiplexed signal and crosstalk component Sk of the frequency spectrum shown in FIG.
The multiplexed signal and crosstalk component Sk of the frequency spectrum shown in FIG. B are alternately extracted every vertical period.

The signals from the heads 1 and 2 are supplied to a high-pass filter 43 through a reproducing amplifier 42, where an FM brightness signal sy is extracted from the multiplexed signal, and this FM brightness signal Sy is sent to a demodulation circuit 45 through a limiter 44. The original luminance signal is extracted, and this luminance signal is supplied to an adder circuit 47 through an amplifier 46.

Further, the signal from the amplifier 42 is supplied to a low-pass filter 52, and a carrier color signal Sc (including the crosstalk component Sk) is extracted.

In this case, as described above and as shown in Figure 8F,
For example, in one vertical period Ta, the carrier frequency f.

a=fc 4fh carrier color signal Sc and carrier frequency f
.

The crosstalk component Sk of b=fo+8fh is extracted, and the carrier frequency f is extracted during the vertical period Tb.

b carrier color signal Sc and carrier frequency f.

The crosstalk component Sk of a is extracted.

The carrier color signal Sc and crosstalk component Sk from this filter 52 are supplied to a frequency converter 51.

Furthermore, in this playback system as well, the recording system circuits 16 to 2
The same circuits 16-28 as 8 are provided.

However, in this case, the oscillation circuits 16 and 17 are variable frequency oscillation circuits, and the synchronization separation circuits 21 and 28 have an amplifier 4.
A luminance signal is supplied from 6.

In this way, the oscillation frequency of the reference 1"f), (f5+8fh) is transmitted from the oscillation circuit 16.17 as in the recording system.
fs4h signal is taken out, and therefore, these oscillation signals are output from the switch circuit 18 by the pulse Pa as 1 as shown in FIG. 8B.
Since it is taken out alternately for each vertical period, converter 2
3, as shown in FIG. 8C, a signal with a frequency (fo + f, ---j f h) is extracted in the vertical period Ta, and a signal with a frequency (fo +'f, +7 fh) is extracted in the vertical period Tb. signal is extracted.

The signal from this converter 23 is transmitted to the converter 51.
supplied to

Therefore, from the converter 51, as shown in FIG. 8G,
In the vertical period Ta, a carrier color signal Ss with a carrier frequency f5 and a crosstock component Sk with a carrier frequency 1 (fs-ifh) are obtained,
In the vertical period Tb, a carrier color l signal Ss with a carrier frequency fs and a crosstalk component Sk with a carrier frequency (f5+-Hfh) are obtained.

That is, from the converter 51, the carrier color signal Ss of the original carrier frequency f5 is continuously obtained, and at the same time, the carrier color signal Ss of the original carrier frequency f5 is obtained continuously. A talk component Sk is obtained.

The carrier color signal Ss and crosstalk component Sk from this converter 51 are supplied to a C-shaped comb filter 54 through a bandpass filter 53.

In this case, since the carrier frequency (f, - z1 fh) or (f5 + Hfh) of the crosstalk component Sk is in an interleaved relationship with the carrier frequency f8 of the carrier color signal Ss, this filter 54 removes the crosstalk component. Sk is removed and only the carrier color signal Ss is taken out.

This carrier color signal Ss is then supplied to an adding circuit 47,
Therefore, the original NTSC color video signal without inter-track crosstalk components is obtained at the terminal 55.

In this case, if the phase of the reproduction system pulse Pa is reversed and the switching phase of the switch circuit 18 is reversed, the frequency-related carrier color signal Ss and crosstalk component Sk as described above cannot be obtained from the converter 51. .

To prevent this, in this example, the pulse P from the head 36 is
e is supplied to the waveform shaping circuit 61, and its shaped output is supplied to the flip-flop circuit 22 as its control signal to control the inversion operation of the flip-flop circuit 22 by the vertical synchronizing pulse. The switching phase of is assumed to be in the correct state.

Further, an oscillation circuit 63 is provided, and from this the oscillation frequency f5
The oscillation signal is supplied to the phase comparison circuit 64, and the carrier color signal Ss from the filter 54 is supplied to the burst gate circuit 65 to extract a burst signal.This burst signal is supplied to the comparison circuit 64 and then the oscillation circuit The phase of the carrier color signal Ss from the filter 54 is stabilized.

In this manner, according to the present invention, color video signals can be recorded with the width of the guard band between the adjacent magnetic tracks 5A and 5B narrowed, or with no guard band, or even with the guard band partially overlapping. The amount of recording can be significantly increased.

Further, since all the carrier color signals Ss are recorded and there is no crosstalk between tracks, the S/N of the reproduced carrier color signals Ss is good and a clear color screen can be reproduced.

Furthermore, even if the color video signal to be recorded is, for example, a reproduction signal from another VTR and there is a time axis error (jitter) in the luminance signal, during recording, the carrier color signal Ss will change to the carrier color signal Sc.
Since the alternating signal that performs the frequency conversion is synchronized with the horizontal synchronizing pulse, the carrier color signal Sc and the luminance signal have the same time axis fluctuation, and therefore no hue fluctuation occurs in the reproduced image. .

FIG. 9 shows another example of the present invention, and this example is a case of.

That is, a variable frequency oscillation circuit 71 is provided, from which an oscillation signal with a reference frequency of 4 fob is supplied to one contact of the switch circuit 18, and is also supplied to a step-down circuit 72, where the frequency is divided by 7.
feb signal and then supplied to the multiplier circuit 73.
20 is supplied to the switch circuit 18 to produce a signal with a frequency of 5 times higher than that of 7''cb-4fca, and this signal is supplied to the other contact of the switch circuit 18.

The switch circuit 18 is switched every vertical period by the pulse Pa, so that a signal with a frequency of 4 feb and a signal with a frequency of 4 foa are alternately taken out from the switch circuit 18 every vertical period.

The signal from this switch circuit 18 is supplied to a step-down circuit 74, where it is stepped down to a frequency of 4, and the signal from the step-down circuit 74 is given a frequency of f.

b signal and frequency f.

A signal is taken out alternately every vertical period, and is supplied to the converter 23.

Further, this converter 23 is supplied with a frequency f from an oscillation circuit 75.
8 oscillation signals are supplied.

Therefore, a signal at frequency (f8+fob) and a signal at frequency (f8+foa) are alternately taken out from the converter 23 every vertical period, and these signals are supplied to the converter 31, so that the signal at the carrier frequency f is output from the converter 31.

b's carrier color signal Sc and the abduction frequency f.

The carrier color signal Sc of a and the carrier color signal Sc are obtained alternately every vertical period.

Thereafter, recording on the tape 3 is performed in the same manner as in the example shown in FIG.

In this case, the signal from the down-down circuit 72 is supplied to the down-down 1 circuit T6 and converted into a signal of the west frequency, that is, the frequency fh, and this signal and the horizontal synchronizing pulse from the separation circuit 28 are sent to the phase comparison circuit 27. The comparison output is supplied to the variable frequency oscillation circuit 71 as its control signal, and its oscillation frequency is maintained at 4 feb.

FIG. 10 shows a reproduction system corresponding to the recording system of FIG. 9, in which a down-down circuit 74 outputs a signal of frequency fcb and a signal of frequency f, similar to the recording system.

The signal a is taken out alternately every vertical period.

The signal from the down-down circuit 74 is supplied to the converter 23, and the oscillation signal with a reference frequency of f5 is supplied from the variable frequency oscillation circuit 81 to the converter 23. A signal of (f5+foa) is taken out alternately every vertical period, and this signal is supplied to the converter 51.

Therefore, a carrier color signal Ss without a crosstalk component Sk is obtained from the filter 54.

In this example as well, the burst signal from the burst gate circuit 65 and the oscillation signal from the oscillation circuit 63 are phase-compared in the comparison circuit 64, and the comparison output is supplied to the variable frequency oscillation circuit 81 as its control signal. The reference phase of the carrier color signal Ss from the filter 54 is stabilized.

As described above, according to the present invention, color video signals can be magnetically recorded at high density, and the recording amount can be significantly increased.

Furthermore, the S/N of the reproduced carrier color signal Ss is good, and a clear color image can be reproduced.

In the above description, the C-shaped comb filters 32 and 54 are
This can be done by using a delay circuit that delays an input signal by one horizontal period and a subtraction circuit that subtracts one of the input signal and the delayed signal from the delay circuit.

For example, when recording a PAL color video signal, f c bf ca = 4 ( 2 k
l) f h.

Furthermore, although the above description deals with recording color video signals on a magnetic tape, the present invention can also be applied to recording on a recording medium such as a magnetic sheet.

[Brief explanation of drawings]

FIG. 1 is a plan view of an example of a rotating magnetic head device, FIG. 2 is a diagram showing an operating gap of the magnetic head, FIG. 3 is a diagram showing a magnetic track, and FIGS. 4 and 5 explain the present invention. FIGS. 6 and 9 are system diagrams showing an example of the present invention, FIGS. 7 and 10 are system diagrams showing an example of the reproducing system, and FIG. 8 is a system diagram showing an example of the reproduction system, and FIG. FIG. 32 is a C-shaped comb filter, 13 is an FM modulation circuit, 23
．． 31 is a frequency converter.

Claims (1)

[Claims] 1. During recording, a color video signal is separated into a luminance signal and a carrier color signal, the separated luminance signal is converted into an angle-modulated signal, and a synchronization pulse is generated from the separated luminance signal. The variable frequency oscillation circuit is oscillated synchronously so that the extracted synchronous pulse and the oscillation signal of the variable frequency oscillation circuit are synchronized, and the frequency of the oscillation signal is converted to form an alternating signal. The frequency of the separated carrier color signal is converted to the lower frequency side of the angle-modulated signal so that the frequencies are substantially interleaved with each other in adjacent tracks, and the frequency-converted carrier color signal and the frequency-modulated signal are The angle modulated signal is added to the angle modulated signal, this added signal is recorded on a recording medium, and when reproduced, the angle modulated signal and the low frequency converted carrier color signal are separated from the reproduced added signal. The original luminance signal is demodulated from the distorted angle-modulated signal, a synchronization pulse is extracted from this demodulated luminance signal, and the above-mentioned variable frequency oscillator is A frequency oscillation circuit is synchronously oscillated, the frequency of the oscillation signal is converted to form an alternating signal, and the separated carrier color signal is re-frequency-converted to the original frequency band by this alternating signal, and this re-frequency conversion is performed. The resulting carrier color signal is supplied to a comb filter to remove crosstalk from adjacent tracks, and the carrier color signal from which crosstalk has been removed is added to the original luminance signal to produce the original color image. A method for recording and reproducing color video signals in which a signal is obtained. 2. A separation circuit that separates a color video signal into a luminance signal and a carrier chrominance signal, an angle modulation circuit that converts the separated luminance signal into an angle-modulated signal, and a separation circuit that converts the separated luminance signal into an angle-modulated signal; and a converter circuit that converts the frequency of the angle-modulated signal to the lower frequency side so that the frequency is substantially interleaved with each other. At the same time as recording on a recording medium, a synchronization pulse is extracted from the separated luminance signal, and the variable frequency oscillation circuit is synchronously oscillated so that the extracted synchronization pulse and the oscillation signal of the variable frequency oscillation circuit are synchronized. The color video signal according to claim 1, characterized in that the frequency of the oscillation signal is converted to form an alternating signal, and the alternating signal is used to perform the frequency conversion in the converter circuit. A recording device for color video signals used in recording and playback methods.