JPH01114189A - Video signal recorder - Google Patents

Abstract

PURPOSE:To separate a chroma signal without deteriorating the characteristic by converting a signal of a band including the chroma signal into a low frequency, supplying it to a comb-line filter utilizing a CCD so as to separate the chroma signal subject to low frequency conversion. CONSTITUTION:A video signal of a band centering the subcarrier of a chroma signal is extracted by an HPF 4 and fed to a frequency conversion circuit 5. Even after the signal is frequency-converted into a low frequency by the circuit 5, when the luminance signal component and the chroma signal are in a prescribed relation, the luminance signal component and chroma signal are separated by using the comb-line filter 7 utilizing the 1H CCD delay line 8. In the actual VTR, the PS(crosstalk prevention processing) is applied. Then the filter 7 is constituted as shown in figure and when the filter 7 introduces a signal not subject to PS processing by a changeover switch 15, the output of an adder 13 is selected and in the case of the signal subject to PS processing, the output of a subtracter 14 is selected. Thus, the low frequency conversion chroma signal is separated without deterioration in the characteristic.

Description

Detailed Description of the Invention (a) The field of industrial application The invention relates to a video signal recording device that separates a luminance signal and a chroma signal from a composite color video signal, converts the chroma signal to a low frequency signal, and records the signal. Conventional technology In a video signal recording device such as a video tail recorder (VTR), a composite color video signal is separated into a full brightness signal and a chroma signal, and each is fully processed and recorded on a recording medium. The brightness signal is FM modulated,
The chroma signal has a frequency of f% in the low range (approximately 600 KHz).By the way, the composite color signal (PAL color signal, NTS
A comb filter is used to separate a C color signal, etc. into a luminance signal and a chroma signal using an (IH) delay @ (H is the horizontal synchronization period). Jitsukai Showa 60-6385, HO4
N9/83) Glass delay line or C
OD is used.

The glass delay line has a narrow pass band and is inferior in terms of susceptibility and waveform distortion, making it impossible to realize a comb filter with good characteristics.Therefore, recently, comb filters using CCD2 have been used.

However, since the COD operation is basically a sampling and holding operation, the aperture effect (the aperture effect is explained in the Journal of the Television Society Vol. 1.39. No.
1l, P, IU15), the high frequency characteristics deteriorate.

Pl The present invention solves two problems: In the conventional C0D2 type filter, there was a problem of deterioration of high-frequency characteristics. The entire signal in the band included in the chroma signal is converted to a low frequency band, and then fed to a comb filter using -COD=i to separate the entire low frequency converted chroma signal. Since the entire low frequency range is utilized, there is less deterioration in characteristics □(f) Example The following is a detailed explanation of the non-invention according to the drawings □ Fig. 1 shows the following:
7F shows the schematic configuration of the invention □ In Figure 1, the mountain indicates the video signal to be recorded (for example, PA
L color @ or NTSC color signal) input terminal, 12
Is + the luminance component? Low bass filter (L) for separation
3F), 1:3) is an FMf adjuster, and 14+ is a bypass filter (HPF) for separating the chroma signal into all bands.
-15+ is a frequency converter for converting the chroma signal to a low frequency band, 16+ is an oscillator that oscillates the entire carrier for frequency conversion, and 17+ is a CCD (t H) delay line 181? This is the comb filter used.

11 (1. stands for a magnetic head for recording, and is abbreviated.) It is well known that actually a pair of rotating magnetic heads are used to trap recording and reproduction. The structure of the first □□□ is as follows.
The video signal in the band centered on 'i' is extracted by the HP F IJ and supplied to the frequency conversion circuit (51).Then, the input signal of the frequency conversion circuit (51) is the chroma signal and the luminance @
Contains a portion of the issue.

The signal extracted by Hk'F+J is frequency converted 515rVC! Even after the frequency is shifted back to the low range, if the brightness signal component and the chroma signal have a predetermined relationship, then the IHC'CD delay line (81) Separation of signal components and chroma signals is performed.

In an actual V-TR, when recording, the chroma signal is diffused to the low frequency range, and crosstalk prevention processing between adjacent tracks called PS-PI is applied. ? The filter is changed in a predetermined manner. Next, the configuration of the comb filter when the above-mentioned crosstalk prevention processing is performed will be explained.

V) (The S method PAL signal processing method is set to an odd multiple of the low frequency conversion frequency y2fg/B.
(f■ is the horizontal synchronization frequency)nFurthermore, the phase is not changed in ACh 7-/N, and PS processing is performed to delay the phase by 90 degrees for each IH on 8ch. The chroma signal is set to 1/8 line offset. Therefore, the entire 2H (H is horizontal period) delay line passes through, and the next output has a phase lead of 90 degrees with respect to the input. On the other hand, in the case of a low frequency converted chroma signal processed by PS, at the input and output of the 2H delay line, )+8
The processing is delayed by L times 180 degrees, and the signal is 9 in 2H.
Since it advances by 0 degrees (see the above explanation), the phase of the 4@station is delayed by 90 degrees.

Therefore, if the phase t of the 2H delay line output without PS processing is set to 90 degrees, the low-frequency converted chroma signal will be in phase. For the 1PS processed signal from which the chroma signal can be extracted, if the phase of the 2H delay line output is delayed by 90 degrees, the phase will be delayed by 180 degrees, and the C and vcj Q low-frequency conversion chroma signals will be subtracted from the non-delayed signal. The signal can be extracted.

In other words, if we configure the block as shown in Figure 2 and use it as a comb filter, then in -1(8), aυ is 2HC.
CD delay line (H corresponds to PAL signal), (1
21 is an ideal phase shift circuit (delays the phase of the low frequency conversion chroma signal by t-90 degrees), 0 is an adder, ■ is a subtracter, and f151 is a changeover switch, which is used as a head switching signal! - is subject to restriction.

In other words, the selector switch a51vcxr) selects the adder 0 output when deriving a signal that is not subjected to PS processing.

In the case of a PS-processed signal, select all outputs of the subtraction 3141 □ Also, the low frequency converted chroma signal can be separated without deterioration of characteristics.Next, let us consider the processing of the NTSG color signal of the VH3 system. For NTSC signals, the frequency of the low frequency converted chroma signal is 40 fH, and for Ach, the phase is set by 90 degrees for each IH. Proceeding further, in the sch, the phase is delayed by 90 degrees for each IH. Therefore, in the comb filter of the zH delay line, it is sufficient to take into account only the phase change L in the PS processing.

In Ach, which advances the phase by 90 degrees, IH (H, N
(Compatible with TSC method) The phase of the M extension line output should be shifted by 90 degrees and added to the non-delayed signal.For Bah, which is delayed by 90 degrees, the phase of the IH delay line output should be delayed by 90 degrees, It is sufficient to subtract it from the non-delayed signal. Therefore, if the comb-shaped filter is configured as shown in No. 3 (2), it will be possible to subtract it from the non-delayed signal. In the NTSC color signal, the chroma signal is converted to the entire low frequency range, but the frequency of the low frequency converted chroma signal is set by a 1/4 fin offset, and only the BCh signal is fully phase inverted for each IH ( PI method) ACh without 0 phase change
So, the output of the IH delay line (H corresponds to +NT, SC method O) has a phase lead of 90 degrees relative to the input, so 90 degrees phase? By delaying and adding, the entire low-frequency converted chroma signal can be extracted.In the Bch, which performs all OPI processing, the phase inversion and 90 degree phase advance are combined, and the output of the IH delay line is 9 for input
This means that the phase is delayed by 0 degrees.

Therefore, by delaying this output by 90 degrees and subtracting it from the non-common signal, a low-pass converted chroma signal can be obtained.In other words, a comb-shaped filter configuration as shown in FIG. 4 can be considered.

In addition, in FIGS. 2, 3, and 4, the 90-degree phase shift means σ2 can also be provided upstream of the delay line α11.

Actually, the delay time kPJr constant (IH or 2H
): All you need to do is reduce V and adjust the phase and delay amount using the phase shifter. Also, is it a comb filter? The configured COD delay mu can be used as a delay line for removing crosstalk during playback. FIG. 51 shows another embodiment of the present invention. In the figure, (1) is a video signal input terminal;
14+ is a bypass filter (HPF) for extracting the band of the chroma signal, +5+u first cycle 1N number conversion circuit,
(71 is the comb-shaped filter shown in Figures 2 to m4, (
171 is an input terminal for a head switching signal (181 is a PI
Alternatively, it is an oscillator for oscillating the tth carrier signal in PS processing (operation is controlled by the head switching signal and horizontal synchronization signal).

T! L9 is a comb filter 171;! 7. A second frequency conversion circuit for returning the obtained low-frequency chroma signal to its original band;
■ is the 20th Ubas filter (211 is the first filter of the video signal)
delay means (221 is the third adder, I:3+Ilf:,
F M 2w45, (2) is the second delay means, (241 is the 30th Uba filter, and is the fourth adder c2ti) is the recording amplifier.

Here, in the comb filter (71) of FIG.
The zero-order operation of the D delay line a61, which includes nine delay lines and two phase shift means in FIGS. 2, 3, and 4, will be explained. Of the L P F 141 output converted to low frequency by the first frequency converter +5+, only the low frequency chroma signal is separated into the comb filter (7) of the present invention.

This low frequency chroma signal is converted into the original phase and original band by the second frequency conversion circuit 0, and added to the video signal. The first delay means (211) is inserted to completely cancel the time difference between the HPF (4) and the second LPF (0).

It is inserted in the ninth adder to completely adjust the time difference between the low frequency chroma signal and the FM luminance signal in the fourth adder.

In other words, if this embodiment is modified, it is possible to reduce the luminance signal by 1Ill- by using a chroma signal tone with no deterioration in high-frequency characteristics. 'A comb filter that can be used to avoid deterioration of the high-frequency characteristics of chroma signals?
The effect is great because it can be realized.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are block diagrams of this embodiment, respectively. 14+...Bypass filter, (51...Frequency conversion circuit, (71...Combine filter, I'ltk...
・Magnetic head.

Claims (1)

[Claims] (1) In a video signal recording device that frequency-converts a chroma signal to a low frequency band and records it on a recording medium, the signal in the band including the chroma signal is frequency-converted to a low frequency band and then passed through a comb filter by a CCD, A video signal recording device that separates low-frequency chroma signals.