JPS5839434B2 - Color video signal reproduction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for reproducing color video signals, in which it is possible to reproduce a particularly long time, and also to eliminate crosstalk and time axis errors from adjacent recording tracks, thereby producing high-quality color images. The aim is to allow the player to play over a long period of time.

When recording luminance signals on a magnetic tape or the like, the following method allows long-time playback with a small amount of tape usage.

That is, as shown in FIG. 1, rotating magnetic heads 1.2 are provided with an angular spacing of 1800 degrees from each other, rotate at a rate of 30 times per second, and rotate the magnetic tape 3 along the tape guide drum 4 by approximately 180 degrees. run diagonally over an angular range of

Further, in this case, as shown in FIG. 2, the width direction, ie, the azimuth angle, of the operating caps gl+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 high frequency 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 obliquely recorded 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, 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 high frequency side, so the FM brightness can be adjusted without causing crosstalk between tracks due to azimuth loss. 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 limiter action of the recycled yarn limiter.
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 guard band between adjacent tracks 5A and 5B can be narrowed during recording.
Or, as shown in FIG. 3, adjacent tracks 5A, 5
Track 5A is adjacent so that there is no guard band between B.

The FM luminance signal can be recorded so that 5B partially overlaps, and therefore the recording amount can be increased by a large amount.
You can play for a long time with less tape usage.

On the other hand, in order to magnetically record a color video signal, generally the luminance signal is converted to 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 and , and the FM luminance signal are 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. The azimuth loss of the playback head is small, which causes inter-track crosstalk in the conveyed color signal.Furthermore, the reproduced color video signal has a time axis error (jitter) due to uneven rotation of the head. ) will be included.

If there is a time axis error in the conveyed color signal, this will appear as a variation in hue on the reproduced screen, significantly reducing the image quality.

Taking these points into consideration, the present invention aims to enable long-time playback with a small amount of tape used, and also to prevent inter-track crosstalk and time axis fluctuations from occurring in the carrier color signal during playback. It is something.

Therefore, during recording, the luminance signal is converted to an FM signal so as to occupy the high frequency side of the recordable band, and the frequency of the carrier color signal is converted to the low frequency side of the FM luminance signal, and this frequency-converted carrier color signal is and the FM luminance signal, and in this case, the carrier frequency of the carrier color signal is interleaved in every other magnetic track 5A and every other magnetic track 5B. Select in relation.

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 color signal Sc of carrier frequency fca
The FM signal is recorded as the magnetic track 5A, while the FM
luminance signal sy and carrier frequency f.

The signal multiplexed with the carrier signal SC of the signal B is recorded as the magnetic track 5B.

And in this case, shall be.

Figure 6 shows an example of a recording system, teeth, In this example 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 supplied to the bypass 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 the oscillation circuit 16 outputs a frequency (fs-Tfh) (for example, f8=3.5s
An oscillation signal with a frequency of (f5+7fh) is extracted from the oscillation circuit 17 and supplied to one contact of the switch circuit 1B.
The oscillation signal is taken out, and this oscillation signal is supplied to the other contact of the switch circuit 18.

Furthermore, 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 now on, as shown in FIG. 8A, every vertical period An inverted pulse Pa is formed, and this pulse Pa is connected to the switch circuit 18.
is supplied as its control signal.

Therefore, from the switch circuit 18, as shown in FIG. 8B, a signal of frequency (f3-Tfh) and a signal of frequency (f5+T
fh) signals are taken out alternately 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, from which the reference frequency is set to, for example, f.

-2 (foa + fcb) =: 44fh (approximately 69
An oscillation signal of 3kHz) is taken out, and this oscillation signal is supplied to the down-down circuit 26 to obtain the ear frequency, that is, the frequency fh.
This signal is supplied to the phase comparison circuit 27, and at the same time, the color video signal from the terminal 11 is supplied to the horizontal synchronization separation circuit 28 to extract the horizontal synchronization pulse, and this pulse is supplied to the comparison circuit 27. be done.

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, the oscillation circuit 25 outputs a frequency f that is locked to a frequency that is 44 times the horizontal frequency fh.

An oscillation signal of =44fh is extracted.

This oscillation signal is then supplied to the converter 23.

Therefore, as shown in FIG. 8C, from the converter 23,
Frequency (fc + fs a f h% times signal,
A signal of frequency (fc+fs+〒fh) is obtained alternately every vertical period.

The continuous wave 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 extract the carrier color signal Ss (carrier frequency f8). A carrier color signal Ss is supplied to the converter 31.

Therefore, the converter 31 outputs the low frequency converted carrier color signal Sc, that is, as shown in the seventh diagram, the carrier frequency is f.
.

a ” 'c A carrier color signal Sc of 41fh 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 head 1.2 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. As shown, the information is recorded on one side of the tape 3 as a magnetic track 6.

When track 5 recorded in this manner is reproduced using head 1.2, as mentioned above, the FM luminance signal sy occupies a high frequency band, so it can be extracted 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. , the carrier frequency f is transmitted from the adjacent track 5B.

The carrier color signal of track 5B (shown by the dotted line) is simultaneously reproduced as a crosstalk component Sk, and as shown in FIG.

The carrier color signal S of b.

In the vertical period Tb during which the track 5 is being played, the adjacent track 5
A to carrier frequency f.

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

However, in this case, in the adjacent magnetic tracks 5A and 5B, the carrier frequencies of the carrier color signal SC are fca and fob, and they are interleaved with each other, so the carrier color signal SC is interleaved with each other.
The carrier frequency f of c.

The carrier frequency of the crosstalk component Sk is interleaved with respect to a+feb.

The present invention utilizes such points to remove inter-track crosstalk components of carrier color signals.

That is, in FIG. 7, when the head 36 reproduces the track 6, a differential pulse Pe of the pulse Pa is taken out from the head 36 as shown in FIG. 8E, and this pulse Pe is supplied to the servo circuit 41. and head 1, 2
and track 5A.

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 bypass 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 through a limiter 44 to a demodulation circuit 45. 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, vertical period 6T""・carrier 6 wave number'...="・-T'
h carrier color signal Sc and carrier frequency f.

The crosstalk component Sk of b-fo+Tfh 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.

A carrier color signal S from this filter 52.

and crosstalk component Sk are supplied to the frequency converter 51, and as shown in FIG.
h),′! ″″′・1 shift period 1″′ is the frequency (fo+
fs-17fh) is supplied.

Therefore, from the converter 51, as shown in FIG. 8G,
In the vertical period Ta, a carrier color signal Ss with a carrier frequency f and a crosstalk component Sk with a carrier frequency (f5-7fh) are obtained, and in the vertical period Tb, a carrier color signal Ss with a carrier frequency f,
A carrier color signal Ss of , and a crosstalk component Sk of carrier frequency (f5-17-fJ) are obtained.

That is, the carrier color signal Ss of the original carrier frequency fs is continuously obtained from the converter 51, and the carrier color signal Ss of the original carrier frequency fs is interleaved with the frequency (fs 'rh) or (f, +Tf1).
1) You can get 0 strokes and 1 stroke Sk.

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 f8 of the carrier color signal Ss and the carrier frequency (fs--HfQ or (f8-1Tfh)) of the crosstalk constituent Sk are interleaved, the crosstalk component Sk is removed in this filter 54. , 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 is obtained at the terminal 55.

Furthermore, during this reproduction, a first time-base error correction circuit is provided to remove the time-base error of the carrier color signal Ss.

That is, the same circuits 16 to 28 as the recording system circuits 16 to 28 are provided, and a luminance signal is supplied from the amplifier 46 to the synchronization separation circuit 21.28.

Therefore, since the variable frequency oscillation circuit 25 outputs an oscillation signal that is phase-locked to the horizontal synchronization pulse of the reproduced luminance signal, the converter 23 outputs an oscillation signal that is phase-locked to the horizontal synchronization pulse and that is phase-locked to the horizontal synchronization pulse of the reproduced luminance signal. As shown in FIG.
8+-7-fh) signal is taken out.

Then, the continuous wave signal from this converter 23 is 1. The carrier color signal Sc is supplied to the converter 51 and subjected to frequency conversion as described above.

In this case, since the signal supplied from the converter 23 to the converter 51 is phase synchronized with the regenerated horizontal synchronizing pulse and has the same time axis fluctuation, the reconverted carrier color signal Sc has a relatively periodic slow and slow time axis fluctuations are removed.

Furthermore, a second time base error correction circuit is also provided.

That is, the oscillation circuits 16 and 17 are made into variable frequency oscillation circuits.

Further, an oscillation circuit 63 is provided, from which the oscillation frequency f
The oscillation signal of 5 is supplied to a phase comparator circuit 64, and the carrier color signal Ss from the filter 54 is supplied to a burst gate circuit 65, where a burst signal containing a time axis error smaller than that of the horizontal synchronization signal is extracted. This burst signal is supplied to a comparator circuit 64 and compared in phase with the oscillation signal from the oscillation circuit 63, and the comparison output is supplied to the variable frequency oscillation circuits 16 and 17 as their control signals.

Therefore, the oscillation signals from the oscillation circuits 16 and 17 have the same time axis fluctuation as the burst signal, and as a result, the continuous wave signal supplied from converter 23 to converter 51 also has the same time axis fluctuation as the burst signal. Therefore, the time axis error of the carrier color signal Ss from the converter 51, that is, the carrier color signal Ss in the color video signal taken out to the terminal 55, is removed and its reference phase is stabilized.

In this case, when the phase of the reproduction system pulse Pa is reversed and the switching phase of the switch circuit 18 is reversed, the converter 51 outputs the carrier color signal S having the above-mentioned frequency relationship.
s and crosstalk component Sk become impossible to obtain.

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 shaping 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, and the pulse Pa is set to a predetermined phase. The switching phase of the switch circuit 18 is set in the correct state.

Thus, according to the present invention, adjacent tracks 5A and 5B
Even if the color video signal is recorded with a narrow guard band width, or with no guard band as shown in Figure 3, or even with a portion of the guard band overlapping, it can be played back. You can play for a long time with less tape usage.

Moreover, in that case, the reproduced luminance signal and carrier color signal S
s does not include inter-track crosstalk components.

Further, since the carrier color signal Ss does not include a time axis error, no hue fluctuation occurs on the reproduced screen.

Therefore, according to the present invention, a clear color image without crosstalk or hue variation can be reproduced for a long time with a small amount of tape used, and is particularly suitable as a small device for home use.

FIG. 9 shows another example of the recording system, and this example shows the case of the recording system.

That is, a variable frequency oscillation circuit 71 is provided, from which an oscillation signal with a reference frequency of 4f,b is supplied to one contact of the switch circuit 18, and is also supplied to a step-down circuit 72 to obtain a frequency of 4 feb and a wave number of 7 feb. The signal is then supplied to the multiplier circuit T3 to increase the frequency by five times.

b-4foa signal, and this signal is the switch circuit 1
8 is supplied to the other contact.

The switch circuit 18 is switched every vertical period by the pulse Pa, so that the switch circuit 18 outputs a signal with a frequency of 4fo5 and a signal with a frequency of 4foa.
They are taken out alternately every vertical period.

The signal from this switch circuit 18 is supplied to a down-down circuit 74, where it is stepped down to the upper frequency, and the signal from the down-down circuit 74 is outputted at the frequency f.

The signal at frequency b and the signal at frequency fCa are taken out alternately every vertical period, and are supplied to the converter 23.

Further, this converter 23 is supplied with a frequency f from an oscillation circuit 75.
An oscillation signal of , is supplied.

Therefore, a signal at frequency (f5+feb) and a signal at frequency (fs+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.

The carrier color signal Sc of carrier frequency fca and the carrier color signal Sc of carrier frequency fca 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 transmitted to the down-down circuit 76.
This signal and the horizontal synchronizing pulse from the separation circuit 28 are supplied to the phase comparison circuit 27 and compared in phase, and the comparison output is sent to the variable frequency oscillation circuit 71. as its control signal, and its oscillation frequency is maintained at 4fod.

FIG. 10 shows a reproduction system according to the present invention corresponding to the recording system of FIG. 9, in which a down-down circuit 74 outputs a signal of frequency feb and a signal of frequency f as in the recording system.

a(D signal) are taken out alternately every vertical period.

The signal from the step-down circuit 74 is supplied to the converter 23, and the oscillation signal with the reference frequency fS is supplied from the variable frequency oscillation circuit 81 to the converter 23, and the converter 23 generates a signal with a frequency (f5+feb).
A frequency (fs+'ca)(7) signal 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.

Also in this example, 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, it is possible to reproduce for a long time with a small amount of tape used, and moreover, the reproduced carrier color signal S
It has good s characteristics and can reproduce beautiful color images.

In the above description, the C-shaped comb filter 32°54 is
It can be configured by 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, in the case of a PAL color video signal, feb-
fca-'4 (2k 1)fh.

Further, in the above description, the color video signal is recorded on a magnetic tape, but the present invention can also be applied to a case where the color video signal is recorded on a recording medium such as a magnetic sheet.

[Brief explanation of the drawing]

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. 6 and 9 are system diagrams each showing an example of a recording system, FIGS. 7 and 10 are system diagrams each showing an example of the present invention, and FIG. 8 is a system diagram showing an example of the recording system. FIG. 32 is a C-shaped comb filter, 13 is an FM modulation circuit, 23
．． 31 is a frequency converter.

Claims (1)

[Claims] 1. 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 the separated carrier color signal is transmitted between adjacent tracks. The frequency of the angle-modulated signal is converted to the lower frequency side so that the frequencies are substantially interleaved with each other, and the low-frequency-converted carrier color signal and the angle-modulated signal are added, and the added signal is When reproducing the color video signal from the recording medium recorded as the track, the added signal is reproduced, and the co-produced added signal is combined with the angle modulated signal and the low frequency converted carrier color signal. demodulate the luminance signal from the separated angle modulated signal, extract a synchronization pulse from the demodulated luminance signal, form a continuous wave signal phase-synchronized with the extracted synchronization pulse, and The frequency of the separated low-pass converted carrier color signal is converted to the original frequency band by a signal formed based on the wave signal, and this frequency-converted carrier color signal is combined with the crosstalk component from the adjacent track. The crosstalk component contained in the carrier color signal frequency-converted to the original frequency band by the frequency interleaving relationship is removed, and the carrier color signal from which the crosstalk component has been removed is added to the demodulated luminance signal. A method for reproducing a color video signal in which the color video signal is obtained by 2. A color video signal is separated into a luminance signal and a carrier chrominance signal, the separated luminance signal is converted into an angle-modulated signal, and the separated carrier chrominance signals are substantially frequency interleaved with each other between adjacent tracks. The frequency of the angle-modulated signal is converted to the lower frequency side so that the angle-modulated signal is in a state where When reproducing the color video signal from the recording medium, the addition signal is reproduced, the reproduced addition signal is separated into the angle-modulated signal and the low-pass converted carrier color signal, and the separation is performed. The luminance signal is demodulated from the angle-modulated signal, and a continuous wave signal is phase-synchronized with the burst signal of the separated low-pass converted carrier chrominance signal, and this continuous wave signal is used to perform the separated low-pass conversion. The carrier color signal is frequency-converted to the original frequency band, and the frequency-converted carrier color signal is frequency-converted to the original frequency band by a frequency interleaving relationship between the frequency-converted carrier color signal and the crosstalk components from the adjacent tracks. A color video signal reproduction method that removes the crosstalk component contained in the color signal and adds the carrier color signal from which the crosstalk component has been removed to the demodulated luminance signal to obtain the color video signal. . 3. A color video signal is separated into a luminance signal and a carrier chrominance signal, the separated luminance signal is converted into an angle-modulated signal, and the separated carrier chrominance signals are substantially frequency interleaved with each other between adjacent tracks. The frequency of the angle-modulated signal is converted to the lower frequency side so that the angle-modulated signal is in a state where In reproducing the color video signal from the recording medium, the added signal is reproduced, the reproduced added signal is separated into the angle modulated signal and the low-pass converted carrier color signal, and the separated The luminance signal is demodulated from the angle-modulated signal, the synchronization pulse is extracted from the demodulated luminance signal, and the burst signal contained in the separated low-pass conversion carrier color signal and the extracted synchronization pulse are extracted. A continuous wave signal including the phase error and frequency error included in the separated low-pass converted carrier color signal is formed from the above, and this continuous wave signal converts the separated low-pass converted carrier color signal to the original frequency. The crosstalk contained in the carrier color signal frequency-converted to the original frequency band by frequency interleaving relationship between the frequency-converted carrier color signal and the crosstalk components from the adjacent tracks. A method for reproducing a color video signal, wherein the color video signal is obtained by removing the crosstalk component and adding the carrier color signal from which the crosstalk component has been removed to the demodulated luminance signal.