JPS60127895A - Recording method and reproducing method of color video signal - Google Patents

Abstract

PURPOSE:To obtain a stable color picture by superimposing respectively a pilot signal on a luminance signal and a color difference signal in addition to a horizontal synchronizing signal and recording the result to match the timing of the luminance signal and the color difference signal. CONSTITUTION:The pilot signal from a controller 57 is added to the luminance signal at an input terminal 20 by an adder 56, given to a video head 31 via a one-horizontal scanning delay device 25 and an FM modulator 29 and recorded on a tape 33. On the other hand, the color difference signals at input terminals 21, 22 added with the pilot signal from the controller 57 at adders 23, 24 and the result is given to a video head 32 via a time axis compressor 26 and an FM modulator 30 and recorded on the tape 33. At the reproduction side, the pilot signal is extracted from a demodulation signal, the phase of the extracted pilot signals is compared, the signal is delayed equivalently by the phase comparison error to make the timewise timing of the three signals coincident with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention records and reproduces at least one baseband (component) signal consisting of a luminance signal of a color video signal and two color difference signals by compressing or expanding the time axis. The present invention relates to a recording method and a reproducing method in a magnetic recording/reproducing device, an optical disc device, a magneto-optical device, etc.

Conventional configuration and its problems Recently, color video signal recording equipment (such as VTR)
), ENG- for consumer use and broadcasting for news gathering.
Research and development to improve the image quality of both EFPs is becoming more active. As recording methods, various methods are being considered for FM recording baseband (component) signals such as R/G-E and luminance signals (1 color difference signals (RY, B-Y or I, Q)). . Typical conventional examples are shown in Figures 1 to 4.
This will be explained using figures. FIG. 1 is a basic lock diagram of a conventional example, FIG. 2 is a diagram explaining its waveform, FIG. 3 is a diagram explaining its spectrum, and FIG. 4 is a diagram explaining problems.

In Figure 1, terminals 1, 2, and 3 are connected to the brightness signal (
FIG. 2d) RY signal of one color difference signal (FIG. 2e) and EY signal of one color difference signal (FIG. 2f) are input. The luminance signal is FM modulated by the FM modulator 4 and sent to the video head 9.
The information is recorded on the magnetic recording medium 11 in an oblique trajectory. On the other hand, the R-Y signal and the B-Y signal are compressed, for example, by a factor of 2, by the time-base compressor 5, and the R-'Y signal after the R-'Y signal is compressed in the previous horizontal period within one horizontal scanning period. The time-base compressed BY-signal is time-division multiplexed in the horizontal period.

This time-compressed color difference signal is processed by adding the horizontal synchronizing signal from the horizontal synchronizing signal input terminal 6 to the horizontal synchronizing signal of the luminance signal in a specific relationship in the adder 7, as shown in Fig. 2 (q). Obtain a time-compressed color difference signal. This time-compressed color difference signal is F
After being FM modulated by the M modulator 8, the video head 1
With ◯, the signal is recorded as a vertical trajectory on the magnetic recording medium 11 on a track different from the luminance signal. Here, Fig. 3 (a
) indicates the luminance signal band. Figure 3 Φ) is R-Y
and B-Y signal bands. Figure 3(a) is
It shows a color difference signal band that has been compressed twice in time. Of course, (C) has a bandwidth of 2 compared to (1)).
It's doubled.

Now, during playback, the video heads 9 and 1O play back the luminance FM signal and the time axis compressed color difference FM signal.
The M demodulators 12 and 13 produce reproduced luminance signals (
FIG. 2 d) and time-domain compressed color difference signals (FIG. 2 q) are reproduced. Then, the time axis compressed color difference signal is sent to a time axis expander 14.
As a result, the original color difference signal RY signal (FIG. 2 e, but the synchronization signal is attached) and BY signal (FIG. 2 f) are changed.

On the other hand, although the reproduced luminance signal (12 outputs) is not shown,
The fixed delay line delays the signal by an amount corresponding to the amount of delay due to time compression and expansion of the color difference signal. Then, the luminance and chromaticity timing corrector 15 automatically matches the times of the luminance signal and the color difference signal, which are caused by the mounting position error of the luminance and color signal heads. The method is to insert the horizontal synchronization signal of the luminance signal and the recording time included in the color difference signal.
The phase of the ζ reproduced horizontal synchronization signal is compared, and the variable delay line is controlled by the error signal to simultaneously vary the two color difference signal delays and match the timings of the luminance signal and the color difference signal.

Although not necessarily required, in order to completely remove screen shaking, time axis fluctuations (jitter) are removed by a well-known time axis corrector 16.

Therefore, the reproduced luminance signal, the RY signal, and the BY signal are obtained at the output terminals 17, 18, and 19, respectively.

Actually, the horizontal synchronization signal of the color difference signal added during recording is removed after the time axis corrector 16.

However, such a recording method in which the time axis compression ratios of the color difference signal and the luminance signal are different has the following problems. In the case of the conventional example shown in Fig. 1 - compared to the luminance signal, the time axis compression ratio of the color difference signal is 2, and Fig. 2 (d) and ((1)
When recorded as FM, the time-compressed color difference signal has twice the frequency of the input color difference signal, and is subject to twice the time fluctuation during playback compared to the luminance signal. However, since the synchronization signal frequency is equal to the horizontal frequency (:l'H) for both the luminance signal and the time-axis compressed color difference signal (Fig. 2q), they are subject to the same time-axis fluctuation.

Therefore, during playback, even if the time-base compressed color difference signal is expanded and restored, the amount of time-base fluctuation (jitter) differs between the color difference signal and the synchronization signal of the color difference signal. Furthermore, the amount of jitter between luminance and chromaticity during the same period also differs because different heads are used. However, due to the amount of time difference between the synchronization signals of the luminance signal and the color difference signal, even if the timings of both signals are made to match, the timings do not match, and as shown in Figure 4, the luminance signal (solid line) On the other hand, the color difference signal becomes undulating as shown by the broken line. That is, if the amounts of jitter do not match, there is a drawback that the amount doubles during playback expansion and appears larger. When compatibility and dubbing were performed, the degree of damage gradually increased, making it unusable, especially in broadcast specifications. Furthermore, this problem becomes more serious as the time-axis compression ratio increases.

Purpose of the Invention In view of the above points, the present invention provides at least a little time axis compression (
The purpose of this method is to match the timing and jitter of the luminance signal and the color difference information to stably obtain a color image in a method in which the information is recorded after being expanded (expanded) and then recorded using a time extraction pressure (m) during playback.

Structure of the Invention The present invention records a luminance signal and a color difference signal by superimposing a pilot signal on each signal separately from a horizontal synchronization signal, and detects time axis fluctuations or changes in which the pilot signal and the luminance signal or color difference signal completely match. The pilot signal is adapted to receive timing fluctuations, and the timings of the luminance signal and the color difference signal are made to match during reproduction.

DESCRIPTION OF THE EMBODIMENTS The present invention can be applied to all methods for recording at least one of the baseband signals by compressing (expanding) the time axis, but for convenience of explanation, the conventional example shown in FIG. An example in which this is applied will be described in detail with reference to FIGS. 5 and 6. Color video signal baseband signal.

Define B and C. A, B, and C are, for example, R2O, B
or a luminance signal, R-Y signal, B-Y signal or luminance signal,
These include an I signal and a Q signal. The present invention is based on these eight, B, and C.
This method is effective for recording a method in which at least one or more signals are compressed or expanded in the time axis, and also for a method in which the compression or expansion rate differs between signals.

Furthermore, the time axis compression ratios of signals A, B, and C are defined as m, n, and q, respectively, with respect to the original signals. And m, n
, q=1 means that the original signal remains as it is. That is, it means that it is neither compressed nor expanded. m, n, q>
1 means that the time axis is compressed. Also, 0<m, n
, q<1 means that the time axis is expanded. FIG. 6 is a basic block diagram of the present invention, and FIG. 6 is an explanatory waveform diagram thereof. To explain FIG. 6, as an example, A is a luminance signal, compression rate m=1. B is the R-Y signal of the color difference signal, compression rate n, = 2, C is the B-signal of the color difference signal.
Assume that the Y signal and the compression ratio q=2.

In FIG. 6, 20, 21, and 22 are luminance signal, RY signal, and BY signal input terminals, respectively. The waveforms are shown in Fig. 2 (d), (e), and (f), and the signal band is as shown in Fig. 3 (-).
=4MH2, the RY signal and the BY signal are Y=1, csMHz as shown in FIG. 3(b). The luminance signal at the input terminal 20 is generated by a controller 67, and the pilot signal is added by a pilot signal adder 66 to obtain the waveform shown in FIG. 6(h). and 1 horizontal scan delay device 26
After delaying the signal by one horizontal scanning period and matching the timing so that the signal is on the same line as the time-axis compressed color difference signal, which will be described later, the FM modulator 29 outputs, for example, 4.3M.
An FM wave with a frequency shift of Hz to 5.9 MHz is recorded on a tape 33 by a video head 31. On the other hand, the color difference signals R-Y and B-Y signals at the input end 21.22 are obtained by adding the pilot signals generated by the controller 67 in the pilot signal adder 23.24 in the same way as the luminance signal, and as shown in FIG. i)
, (D. Then, in the time axis compressor 26, memory elements such as pccD are driven by the write clock and escape clock generated from the controller 6γ, and the color difference signals including the respective pilot signals are doubled. In addition, the compressed signals are time-division multiplexed during one horizontal scanning period to obtain the signal shown in FIG. 6(g). Therefore, controller 5
7 creates a pilot signal and a write clock and escape clock for time axis compression.

In creating this, for example, a continuous wave that is phase synchronized with the horizontal synchronization signal of the input luminance signal is generated. Naturally, if the write clock frequency is fl, the read clock frequency f2 is f2-2f1. Moreover, f1
vf2 is also phase synchronized with the horizontal synchronization signal.

Now, in the time-axis compressed color difference signal shown in FIG. 6 (8)), the horizontal synchronization signal from the synchronization signal input terminal 27 has a specific relationship with that of the luminance signal (in FIG. The adder 28 adds the data so that the edges match (relationship in which the edges match) to obtain FIG.
The FM wave has a frequency shift of Hz, and is recorded on a tape 33 by a video head 32. Next, pilot signal generation, which is the main part of the present invention, will be explained in more detail. The pilot signal is determined from the following viewpoints. First, the pilot frequency is within the baseband band of the baseband signal before being subjected to time axis pressure 1na. In other words, for the luminance signal, a pilot frequency below band X (FIG. 3a) is selected. Similarly, the color difference signal (R
-Y, B-Y), a pilot frequency below band Y (FIG. 3b) is selected. Furthermore, for frequency selection,
Moiré is taken into account.

In other words, there is generally a lot of moiré near the upper limit of the band, so avoid using that area as much as possible. Furthermore, in order to reduce residual jitter after time base correction during playback, the higher the pilot frequency is, the better. Taking these three points into consideration, for example, the same frequency of about 1 MHz is selected for the luminance signal and the color difference signal.

The required bandwidth after time axis compression is equal to the baseband bandwidth multiplied by the compression ratio, and as shown in Figure 3(c),
The band will be 2Y. If the pilot frequency is selected to be 1 MHz, the frequency after compression will be 2 MHz. It is within the required band 2Y.

Second, regarding the pilot phase, all three signals are made to have the same phase when superimposed. Alternatively, the color difference signals have the same phase, and the luminance signal has a 9oO phase. Thirdly, regarding the pilot superimposition period, in FIG. 6, before compression,
Although the periods are assumed to be the same, they do not necessarily have to be the same.

For example, the periods may be set to be approximately the same period after compression.

As described above, in this embodiment, the same frequency is superimposed before compression, and the color difference signal is compressed on the time axis including the superimposed pilot. Therefore, in the compressed color difference signal, the circuit phase in the controller 57 is Even if a drift occurs, a specific relationship can be maintained between the color difference signal and the pilot signal.

Now, when reproducing the signal, the signal from the video head 31 is temporarily modulated by the FM demodulator 34 to obtain a reproduced luminance signal, and the time axis corrector 36 removes the 11.1 axis fluctuation. However, this time i11+corrector 36 does not necessarily have to be provided. The 36 outputs after time axis compression are delayed by one horizontal JlfIi period by one horizontal scanning delay device 37 to correct the delay of the color difference signal generated by a time axis expander 4O, which will be described later.

Then, the timing is corrected by a luminance/chromaticity timing corrector 41 that matches the timing of the luminance signal and the color difference signal, the pilot is removed by the pilot remover 6o, and the original luminance signal is converted to (G).

On the other hand, the time-compressed color difference signal is reproduced by the video head 32 and demodulated by the FM demodulator 36 to obtain a reproduced time-axis compressed color difference signal (FIG. 6, 2). And time axis extender 40
The time axis is expanded twice, and the two color difference signals R-Y
, B-Y (FIG. 6(i), (j)), the timings of the luminance signal and the color difference signal are completely matched by the luminance/chromaticity timing corrector 41, and the timing of the luminance signal and the color difference signal is completely matched by the pilot signal and synchronization signal remover 61. and pilot signal remover 62, unnecessary signals are removed and the original color difference signals (RY signal, B-Y signal
signal) (obtained at C-output end 64.55 (Fig. 2(e)
, (f)).

In the following, a description will be given of how the pilot signal superimposed during recording is used during reproduction in accordance with the specific relationship of this embodiment. The output of the FMQ modulator 35 (FIG. 6(k)) is connected to the time base extender 40 as described above and at the same time to the sync separator 38, ) ) signal and synchronization signal are separated. The separated pilot signal and synchronization signal are input to the controller 39. The controller 39 is a time axis expander 4 composed of a memory device such as a COD.
Generates a write clock and a read clock that drive 0. The extracted pilot signal (frequency 2
MHz) to PLI, etc. Continuous wave (
For example, s MHz, 4)yiHz) is created. This BMHz signal is the write clock frequency, the 4MHz signal is the read clock frequency, and, for example, the signal for one horizontal scanning period from t=Q in FIG. 6(k) is stored in the first memory. ) 11 Written by Kikomiri Lock. In this case, the write clock is obtained by gating an sMHz signal and a signal obtained by dividing the trailing edge of the synchronization signal by h.

Furthermore, the first memory is divided into two sections, in which the first half of the R-Y signal for one horizontal jυ'' is written, and the second half of the B-Y signal is written in the other section. Write down. The readout starts from the beginning of the next horizontal period at t=11 with 4MH created in the same way as the above writing.
With the read clock of z, the two memory sections are read simultaneously to obtain FIG. 6(i) and 0). This is the output of the time axis expander 4Q. Also, time axis expander 4
o also has a second memory, and during the horizontal period starting from 1=11 when escaping the first memory, the second memory is written in the same way as the first memory, and the second memory is written in the next horizontal period. Read the memory contents of . The pilot frequency and color difference signal frequency of the color difference signal whose time axis has been expanded in this manner become the original frequencies. Naturally, both signals have the same time axis fluctuation. At this time,
The synchronization signal is also time-expanded and exists for each horizontal scanning period of the synchronization signal included in the R-Y signal, but the amount of time axis variation is equivalent to the half frequency of Cedar Water. Now, the luminance signal (37 outputs) obtained in this way.

R-Y signal (4o output), B-Y signal (40 output) are
It is connected to a luminance/chromaticity timing corrector 41 .

Conventionally, this circuit compared the phases of the luminance signal and the synchronization signal of the R-Y signal, and controlled a variable delay line composed of COD etc. to match the timing of luminance and chromaticity. Then, as described above, the jitter amount is different between the synchronization signal of the luminance signal and the color difference signal, and the amount of jitter is also different between the synchronization signal of the color difference signal and the color difference signal, so that the phenomenon shown in FIG. 4 occurs. Therefore, in this embodiment, the fixed delay line 4
A pilot signal is extracted by a pilot signal separator 43 from the luminance signal delayed by a predetermined amount of time in step 2. This frequency is 1 MHz. On the other hand, the two color difference signals each pass through variable delay lines 46 and 49, from which pilot signals are extracted by pilot signal separators 44 + 47. This frequency is also 1MH2. Then, the phase comparator 46 compares the luminance signal and the RY signal at 1 hiHz, and the variable delay line 46 is controlled by the error signal to determine the luminance and chromaticity. Timing correction',:'j; Luminance signal of 41 output and R-Y
signal timing. , L matches. Similarly, phase comparator 4
Then, the luminance signal and the pilot signal of the B-Y signal are compared in phase, and the error signal is used to calculate the variable delay I%! 49
That's it! As a result, the timings of the luminance/chromaticity timing corrector 41 output signal 111 and the BY signal match. Therefore, the three baseband signals output from the luminance/chromaticity timing corrector 41 match. Here, since the pilot signal frequency is a relatively high frequency of 1 MHz, the timing pressure regulation accuracy is very good. If only the phase comparison of the pilot signals causes overflow due to a large head mounting error, it is better to provide a phase comparator for synchronizing signals as in the past. However, since the amount of time-axis variation is the same, the response is very slow (below the field frequency) and can be used to prevent noise.

Next, we will briefly explain an application example in which time axis correction is also performed. In this case, the luminance signal is A/D (converted from analog to digital) by the time axis corrector 3e and written into the memory. The write clock separates a pilot signal and a synchronization signal from the output of the FM demodulator 34, creates a write clock whose phase is synchronized with the pilot signal, and controls the write clock with the synchronization signal to write it into the memory. . Similarly, the color difference signal is also written into the memory of the time axis expander 4o. However, it is sufficient to A/D the output of the FM demodulator 35. The luminance signal and color difference signal are read out using a reference signal. At this time, it goes without saying that the color difference signal is a 4 MHz reference signal. Regarding luminance/chromaticity timing correction, as in the basic operation of the luminance/chromaticity timing corrector 41, the pilot signals are phase-compared, and the read-out timing of only the chrominance signal is phase-modulated based on the error.

After that, just do D/8. In this case, another method is to compare the phases of the luminance signal and the pilot signal of the color difference signal (9JR-Y signal) at the time of writing, and use the error signal to phase-modulate the synchronization signal extracted from the color difference signal. It is also possible to control the writing timing of the shaft expander 40 and perform reading using a reference signal.

An embodiment of the present invention has been described above, but in FIG. 6, it is also possible to use only the R-Y signal as the pilot signal for the color difference signal and omit the pilot signal for the B-Y signal. . In this case, Le 1 [degree/chromaticity timing corrector 4]
Pylon i of 1/molecule 111: '? , :÷47 and the phase comparator 48 may be omitted, and the variable delay line 49 may be controlled by the output of the phase comparator 46.

Regarding pilot superimposition, even if the color difference signal is compressed by 2 MHz for the luminance signal in FIG. 6 of the embodiment, it is also possible to use a pilot signal of the same frequency as 2 MHz before recording. This means that the pilots are recorded at the same frequency after being subjected to time compression or expansion rates m, n, q. in this case,
During playback, the time axis expander (compressor) and time axis corrector are configured as a common circuit, which is very useful when timing is corrected on the recording side.

Application examples of the present invention include not only the recording method described in FIG. 6, but also any method in which at least one baseband signal is compressed or expanded in the time axis and recorded. For example, one horizontal period of the luminance signal is expanded to one horizontal period or more (1.5 times), and the line-sequential color difference signal is compressed on the time axis by 2 times (0,5H)j, and then the time division is performed. A method in which signals are multiplexed and recorded on one track, and the remaining horizontal period signals are similarly recorded on another trunk.

Alternatively, as shown in Fig. 7 (0), the color difference signal is converted into a line sequential signal, and the line sequential signal is compressed in the time axis, and the luminance signal is also compressed in the axis by 115 (compression ratio 1; 2) and 1 horizontal line. A method in which line sequential signals and μm I degree signals are time-division multiplexed and recorded during a period.

Alternatively, as a modification of FIG. 7(0), the R-Y signal, the B-
This method can be applied to a method in which the Y signal is compressed on the time axis, the luminance signal is also compressed on the time axis, and three baseband signals are time-division multiplexed and recorded within one horizontal scanning period. According to the present invention, the lower the compression ratio (11F1), the more effective the pilot signal becomes.

Effects of the Invention As described above, in the present invention, in a method in which at least one of the three baseband signals A, B, and C is recorded after being time-axis compressed or expanded, within the baseband band. A pilot signal with a frequency that takes into account moiré and timing accuracy is superimposed on each signal A, B, and C for a specific period with a specific phase relationship, and the baseband signal including the pilot signal is compressed at compression ratios m, n, and q. After compressing or expanding the time axis, the signals are recorded by FM modulation;
By comparing the phases of the pilot signals of each signal and using the resulting error signal, the timing of each signal can be perfectly matched. Furthermore, this pilot signal can also be used as a built-in clock pulse for a time base corrector, and in this case, the timing of each signal can be perfectly matched, and at the same time, time base fluctuations can also be removed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of a conventional color video signal recording/reproducing device, Fig. 2 is a waveform diagram for explaining its operation, Fig. 3 is a spectrum diagram of a baseband signal, and Fig. 4 is a spectral diagram of a baseband signal.
6 is a block diagram showing the basic configuration of a color video signal recording and reproducing apparatus according to an embodiment of the present invention. FIG. 6 is a diagram for explaining the embodiment. FIG. 7 is a waveform diagram for explaining a recording method in another embodiment of the present invention. 23.24,56... Pilot signal adder,
43.44.47...Pilot signal separator,
46,48... Phase comparator, 46.49...
...Variable delay line, 67...Controller. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure cause (4) ] 3 Figure 1 subtext 4 lines (42) Figure 6 Figure 7 Nod 70...1 Symptom number

Claims (5)

[Claims] (1) Three baseband signals A of color video signals. When the baseband signals A, B, and C are time-axis compressed, at least time-division multiplexed, and then FM modulated and recorded, at least one signal of the three baseband signals A, B, and C is compressed over time. The axial compression ratio t is time 1111 + expansion, and a pilot signal within a required band is superimposed during a predetermined period of horizontal blanking of two or more signals having different time axis compression ratios or time 1111 + expansion ratios. A method for recording color video signals. (2) A patent claim characterized in that a pilot signal is superimposed on a baseband signal before time axis compression or time axis expansion, and then the baseband signal including the pilot signal is subjected to time axis compression or time axis expansion. A method for recording a color video signal according to scope 1. (3) A color video signal recording method according to claim 2, characterized in that the frequencies of the pilot signals to be superimposed are the same between the signals, and the phases are set in a specific relationship. (4) The frequency of the pilot signal is the same between two or more signals after time axis compression or time axis expansion, and the phases are set in a specific relationship. The method for recording a color video signal according to item 1. (5) Extract two or more signals from the reproduced FM demodulated signal, compare the phases of the extracted signals, and use this phase comparison error signal to isometrically delay the signal and A method for reproducing a color video signal, characterized by matching the temporal timing of the signals.