JPS593074B2 - Color video signal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Recently, there has been a demand for recorder/player devices, so-called VTRs, to be able to record as long as possible on a tape of a certain length.

To this end, it is sufficient to avoid forming so-called guard pads between recording tracks as in the conventional case. but,
In this case, crosstalk from adjacent tracks becomes a problem during playback. 10 video signals are generally FM modulated and recorded as relatively high frequency signals.

Focusing on this point, the inclination of the magnetic air gap of two rotating magnetic heads forming adjacent tracks is different, and the effect of azimuth loss is used to reduce crosstalk from adjacent tracks during reproduction. Methods have already been proposed. However, this method has disadvantages in the case of color video signals.

This is because, in the case of recording a color video signal, the carrier color signal K0 is subjected to low frequency conversion as described below. That is, as shown in FIG. 1, a color video signal from an input terminal 11 is supplied to a low-pass filter 12 to produce a luminance signal Y.

(Fig. 2A) is taken out and supplied to the FM modulator 13, and the luminance signal YFM (
B) in Fig. 2 is passed through the Ipass filter 14 to the synthesizer 1.
On the other hand, the color video signal is supplied to the bandpass filter 16 to extract the carrier color signal Cs (A in FIG. 2), which is supplied to the frequency converter IT to convert the frequency to the lower side. ".Then, the converted carrier color signal Cl (FIG. 2B) is supplied to the synthesizer 15 through the bandpass filter 18,
Then, the output signal of the synthesizer 15 is supplied to the heads HA and HB through the recording side contacts R of the switches 5 and 6 to be recorded on the tape 1. 15, the reproduction signals from the ADs HA and HB are switched and extracted field by field by the switch circuit 19 through the reproduction side contacts P of the switches 5 and 6, and are supplied to the high pulse filter 20. The FM-modulated luminance signal YFM is extracted and supplied to the FM demodulator 22 through the limiter 21, and the demodulated luminance signal is supplied to the synthesizer 24 through the low-pass filter 23. is supplied to the low-pass filter 25 to take out the carrier color signal CL that has been low-pass converted, and is supplied to the frequency converter 26 to convert it to the original frequency, and converts the converted carrier color signal into the band "Z". The signal is supplied to the synthesizer 24 through the filter 27, and the reproduced color video signal is taken out at the output terminal 28.

As described above, for the luminance signal, the frequency is raised by FM modulation, so the azimuth loss is large and the crosstalk is reduced, but for the carrier color signal, the original carrier frequency Fs is 3.5% in the case of an NTSC signal. 58M [Z. P.A.
In the case of the L signal, it is 4.43 MIz, which is a sufficiently high frequency, but the carrier frequency FL when low frequency conversion is performed is a low frequency of about 680 to 6901c[Iz, so the azimuth loss is small. , so the crosstalk is hardly reduced. In view of this point, the following method has been proposed as a method for reducing crosstalk of carrier color signals.

As shown in FIG. 3, this is the carrier frequency FLA of the carrier color signal CLA that has been low-pass converted in the track TA, and the carrier frequency FLA that has been low-band converted the carrier color signal CLA on the adjacent track TB.
The carrier frequencies FLB of the two signals are slightly different from each other by a certain value so as to have a frequency interleaf relationship with each other.

That is, if the horizontal frequency is FH, the frequencies FLA and F
The difference in LB is set to 72f11 as shown in FIG. 4 in the case of an NTSC signal, and -FH as shown in FIG. 5 in the case of a PAL signal. 4 To do this, prepare two types of frequency conversion signals whose frequencies differ by FH or -4fH, and switch these between track TA and track TB.
Alternatively, the phase of the frequency conversion signal of a certain frequency is
By keeping it constant for track TA and inverting it every one or two horizontal intervals for track TB, the frequency of the frequency conversion signal is equivalently changed between tracks TA and T.
You can use the method of switching with B.

In this way, by making the frequency conversion by the frequency converter 26 during playback correspond to that during recording, the overall bands from the V1 bandpass filter 27 overlap each other, but the The main signal from that track has spectral components distributed at frequency intervals of FH around the carrier frequency F8, and the main signal from the adjacent track has spectral components distributed at a position shifted from this by -2fH to -4fH. A mixture of crosstalk and crosstalk is obtained.

Therefore, after the bandpass filter 27, in the case of an NTSC signal, as shown in FIG.
In the case of a signal, as shown in FIG. 7, a C-shaped comb filter 29 is inserted, each consisting of two delay circuits 30 and 31 each having a delay time of one horizontal period and a subtracter 32. By doing so, crosstalk from adjacent tracks can be removed. However, this method has the following drawbacks.

First, using the comb filter 29,
In the case of an SC signal, the carrier color signals in adjacent horizontal sections are combined, and in the case of a PAL signal, the carrier color signals in one horizontal section are combined, so the vertical direction of the color signal is resolution will decrease.

This is particularly noticeable in the case of PAL signals. Second, a comb filter having a delay circuit with a delay time of one horizontal period is required, which increases the cost. Particularly in the case of PAL signals, two delay circuits are required, which increases the cost. Third, this method uses NTSC
For signals} and for PAL signals, the configuration must be changed. Fourth, the method uses N
This is effective in the case of a TSC signal or a PAL signal, but cannot be used at all if the carrier color signal is an FM signal and is a SECAM signal whose modulation frequency changes every horizontal interval. In view of these points, the present invention provides N
A similar configuration can be used for TSC signals, PAL signals, and even SECAM signals, and the image does not require a comb filter and therefore does not reduce the vertical resolution of the color signal or increase the cost. This method provides a temporary method.

In the present invention, the first carrier color signal CA having the first low carrier frequency FA and the second carrier color signal CB having the second low carrier frequency FB are alternately used as the low frequency converted carrier color signal. At this point, the first low carrier frequency FA
is set to a sufficiently low frequency, for example, about 680 to 6901cIIz, and the second low-band carrier frequency FB is set to a sufficiently higher frequency than this, for example, a frequency close to twice that, and the first carrier color is set as shown in FIG. 8C. The signal CA and the second carrier color signal CB are made to occupy substantially separate and adjacent frequency bands.

As shown in FIG. 9, the first carrier color signal CA is used in the track TA, and the second carrier color signal CB is used in the adjacent track TB, or for example, the first carrier color signal CA is used.
1 at an appropriate timing for each track, as shown in Figure 0.
In every horizontal section, the first carrier color signal CA is used, and in the remaining horizontal section, the second carrier color signal CB is used, and by arranging them alternately, adjacent tracks can be simultaneously In the portion that can be reproduced, the first carrier color signal CA and the second carrier color signal CB are arranged side by side. That is, the first carrier color signals CA or the second carrier color signals CB are prevented from being lined up with each other. A specific example will be explained below using a PAL signal as an example.

FIG. 11 is an example of the case shown in FIG.
For example, the inclinations of the voids in A and HB are made different from each other, as mentioned at the beginning.

10A and 10B are pulse generators for heads HA and H.
are provided at a distance of 18'' from each other in relation to the rotation axis of B,
A pulse with a frame period is obtained from each.

First, to explain the case of recording, the color video signal from the input terminal 11 is supplied to the horizontal synchronizing signal separation circuit 41 via the recording side contact R of the switch 7, and the horizontal synchronizing signal is extracted. Pulses from the pulse generator 10A and pulses from the pulse generator 10B are respectively supplied to the set side and the set side of the flip-flop circuit 42.
A pulse signal whose state is inverted in the field where the head HA forms the track TA and the field where the head HB forms the track TB is formed, and this pulse signal is transmitted to the switch circuit 43.
and 44, the switch circuits 43 and 44
In the field where track TA is formed, on the terminal A side,
In the field where the track TB is formed, it is switched to the terminal B side.

In the field where the track TA is formed, a variable frequency oscillator 4 whose free oscillation frequency is 44fI1 is used.
The oscillation signal of 5 is supplied to the frequency divider 47 through the switch circuits 43 and 44 and divided into 1, and the phase of the divided signal and the horizontal synchronization signal is compared in the phase comparator 48, and the comparison output is used as the oscillator. 45 is controlled, while track TB
In the field where is formed, the free oscillation frequency is 88f
The oscillation signal of the variable frequency oscillator 46 set to H is supplied to the frequency divider 49 via the switch circuits 43 and 44 and divided into 1, and the output signal is further supplied to the frequency divider 47 and divided into 1. That is, the oscillation signal of the oscillator 44 and the horizontal synchronizing signal are divided into one frequency, and the phase of this frequency-divided signal and the horizontal synchronizing signal are similarly compared in the phase comparator 88, and the oscillator 46 is controlled by the comparison output. , As a result, from the switch circuit 43, in the field where the track TA is formed, 4
A signal with a frequency of 4fH is obtained in the field where the track TB is formed, and a signal with a frequency of 88fH is obtained in the field where the track TB is formed.

The signal from this switch circuit 43 is supplied to the frequency converter 50, and fS-IfH (
However, Fs is the original carrier frequency (in this example, since it is a PAL signal, it is 4.4311V1Bz).
Well, in the field where the track TA is formed, a signal with the frequency is obtained, and in the field where the track TB is formed, a signal with the frequency is obtained.

Then, the signal from the frequency converter 50 is supplied to the frequency converter 17, and the carrier color signal Cs whose carrier frequency is Fs from the low-pass filter 16 is frequency-converted.

Therefore, as shown in FIGS. 8A to 8C, the track TA has a first low carrier frequency FA=(44-1) in which the signal Cs is low-frequency converted by a signal with a frequency of Fs+FA. FH
A first carrier color signal CA is recorded on the track TB, and a second low carrier frequency FB-(88-★)FH is recorded on the track TB.
A second carrier color signal CB is recorded. Note that the pass band of the low-pass filter 18 is the same as that of the first and second carrier color signals C.
It is assumed that the A and CB bands are covered. Luminance signal Y taken out from the low-pass filter 12.

is FM modulated by the FM modulator 13, but the recorded FM
The band of the modulated luminance signal YFM is set to occupy the high frequency side of the second carrier color signal CB, as shown in FIG.
The frequency F2 at the z1 white peak is selected to be 5.8M[Iz. Even during reproduction, the frequency converter 26 is supplied with a frequency-converted signal having the same frequency as that during recording.

Therefore, as shown in FIG. 8 C-E, the first carrier color signal CA of the first low carrier frequency FA reproduced from the track TA is frequency-converted by the signal of the frequency Fs+FA, and the carrier frequency is changed. It is made into a carrier color signal Cs of the original frequency Fs, and is taken out from the bandpass filter 27. At this time, the second carrier color signal CB of the second low carrier frequency FB as crosstalk picked up from the adjacent track TB is frequency-converted by a signal with a frequency of Fs+FA, and the carrier frequency becomes Fs-(FB- Since the signal CAB occupies the lower frequency side of the signal Cs in the signal Cs (FA), this crosstalk CAB is removed by the bandpass filter 27. On the other hand, isn't the second carrier color signal CB of the second low carrier frequency FB reproduced from the track TB frequency-converted by a signal with a frequency of Fs+FB? The carrier color signal Cs whose carrier frequency is the original frequency Fs is taken out from the bandpass filter 27. At this time, the adjacent track T
The first carrier color signal CA of the first low carrier frequency FA as a crosstalk extracted from A is frequency-converted by a signal with a frequency of Fs+FB, and the carrier frequency becomes Fs+(
Since the signal CBA occupies the high frequency side of the signal Cs at FB-FA), this crosstalk CBA is removed by the bandpass filter 27. During reproduction, the carrier color signal Cs obtained from the bandpass filter 27 is supplied to the burst gate circuit 52 to extract a burst signal, and the phase comparator 53 compares the frequency of this burst signal and the frequency of the reference oscillator 54 with Fs. The reference signals of are compared in phase,
The comparison output is supplied to the oscillator 51 via the reproduction side contact P of the switch 8, which is controlled and APC is applied. FIG. 12 shows an example of the case shown in FIG. 10, in which a flip-flop circuit 55 separate from the flip-flop circuit 42 is provided, and the horizontal synchronizing signal from the circuit 41 is supplied to this flip-flop circuit 55, and this flip-flop circuit It is inverted for each section, and the signals from this are sent to switch circuits 43 and 4.
4, and this is switched every horizontal section.

Therefore, in FIG. 10, if the tape 1 is running in the direction shown by arrow 2, the head is scanning in the direction shown by arrow 3, and tracks are sequentially formed in the direction shown by arrow 4, Moreover, the recording positions of the heads of the vertical synchronization signals of adjacent tracks are in a circle in the extending direction of the tracks, for example, 1.
．． When the shift is made by a time corresponding to 5H (H is one horizontal period), the switch circuits 43 and 44 are simply switched every horizontal section in this way, and the first and second carrier color signals are The desired pattern as shown in the figure can be obtained by simply extracting CA and CB alternately every horizontal section.

Of course, if this is not the case, the configuration may be such that the inversion phase of the flip-flop circuit 55 and the switching phases of the switch circuits 43 and 44 are controlled for each field.

During reproduction, the flip-flop circuit 55 similarly inverts every horizontal section, but in this case, the reproduction signal from the switch circuit 19 is supplied to the burst gate circuit 56 via the reproduction side contact P of the switch 9, and the frequency is changed. The above-mentioned burst signal of FA or FB is extracted, and this is supplied to the band pass filter 57, and only the burst signal having a frequency of FA, for example, is extracted, and this is supplied to the amplitude detector 58, where the amplitude is detected. Output is level comparator 59
The horizontal section of the first carrier color signal CA and the horizontal section of the second carrier color signal CB of the track being reproduced are determined based on the magnitude of the detection output supplied to During the period of the first carrier color signal CA, the circuit 55 is set to the set state, so that the inverted phase of the flip-flop circuit 55 and the switching phases of the switch circuits 43 and 44 correspond to those during recording. Ru.

}, the first and second carrier color signals CA and CB are taken out alternately every two horizontal sections or every more than one horizontal section, and arranged alternately on the tape 1 in the same manner as described above. It's okay.

Each of the above-mentioned examples is a case where the frequency conversion signal is switched, but as shown in FIG. , one of which has a frequency of F
A continuous frequency conversion signal of s+FA is supplied to obtain the first carrier color signal CA, and a continuous frequency conversion signal of frequency Fs+FB is supplied to the other side to obtain the second carrier color signal CA. The configuration may be such that the carrier color signal CB is obtained, and the first and second carrier color signals CA and CB are switched and taken out by the switch circuit 60, and the same is done during reproduction. It is desirable that the first and second low-frequency carrier frequencies FA and FB are both selected in a -line offset relationship as described above, but even in this case, the difference is, where n is a positive integer, nfi as mentioned above
It may be set as (n±~)FlI without being set as .

According to the present invention described above, long-time recording can be realized with the same configuration for NTSC signals, PAL signals, and even SECAM signals.

Moreover, since there is no need for a comb filter in the regeneration system,
The vertical resolution of the color signal does not deteriorate, and the cost can be reduced, which is particularly suitable for PAL signals.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a conventional device, Figure 2 is a diagram for explaining it, Figures 3 to 7 are diagrams for explaining a conventional long-term recording method of color video signals, and Figure 8 10 are diagrams for explaining the long-term recording method according to the present invention, and FIGS. 11 to 13 are system diagrams of specific examples of the present invention. 17 and 26 are frequency converters, and 41 to 59 are circuits for forming frequency conversion signals.

Claims (1)

[Claims] 1. A frequency converter that converts a carrier color signal in a color video signal to a low frequency range, and a circuit that forms a frequency conversion signal to be supplied to the frequency converter. A first carrier color signal with a first low carrier frequency and a second carrier color signal with a second low carrier frequency that is sufficiently higher than the first low carrier frequency with respect to the first carrier color signal. second carrier chrominance signals occupying substantially separate and adjacent frequency bands are obtained alternately at predetermined switching timings, the switching timings being such that second carrier color signals occupy substantially separate and adjacent frequency bands; is a color video signal recording device selected such that the first carrier color signal and the second carrier color signal are aligned. 2. The color video signal recording device according to claim 1, wherein the switching timing is set to a time interval at which one track is formed. 3. The color video signal recording device according to claim 1, wherein the switching timing is set at a time interval of one or two horizontal intervals.