JPS63299695A - Recorder for color video signal - Google Patents

Abstract

PURPOSE:To obtain an excellent reproduced picture by applying FM modulation to a luminance signal and a high frequency component of a carrier chrominance signal, recording the low frequency component of the carrier chrominance signal while being frequency-converted into a low frequency portion of an FM signal and giving the same jitter as that of the luminance signal to the high frequency component of the carrier chrominance signal added to the luminance signal especially. CONSTITUTION:A broad band carrier chrominance signal C is fed to a subtraction circuit 74 and also fed to a band pass filter 73 of a narrow band to obtain a low frequency component CL of the carrier chrominance signal in fc+ or -0.3MHz. The low frequency component CL is fed to a subtraction circuit 74, where it is subtracted from the carrier chrominance signal C to obtain a high frequency component CH of the carrier chrominance signal, which is fed to a frequency converter 75. A high frequency component having the same jitter as that of the luminance signal and whose chrominance subcarrier frequency is fs* is obtained from the converter 75. It is fed to an adder circuit 65, where it is added to a luminance signal Y and a pilot burst signal PB. In reproducing the signal by the reproducing system, jitter is eliminated from the luminance signal Y and the carrier chrominance signal C and an excellent reproduced picture is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color video signal recording device suitable for use in, for example, a rotary head type VTR.

[Summary of the invention]

This invention combines the luminance signal and the high-frequency components of the carrier color signal.
The low frequency component of the carrier color signal is frequency-converted to the low frequency side of the FM signal and recorded. In particular, the high frequency component of the carrier color signal that is added to the luminance signal has the same jitter as this luminance signal. By assigning , the human color video signal surface to be recorded is
This recording device is capable of obtaining a good reproduced image even when the phase relationship between the luminance signal and the carrier color signal is not constant, such as in the case of an R reproduction signal.

(Prior art) In home VTRs and U standard V'I'Rs,
A color under one type is adopted, and when recording, the luminance signal is converted to FM.
At the same time, the carrier color signal is frequency-converted to a lower frequency than the FM luminance signal, and a frequency multi-frequency signal of the low-frequency-converted carrier color signal and FM luminance signal is recorded. The original color video signal is generated by performing signal processing in the opposite direction (see, for example, literature: Journal of the Society of Television Engineers, Vol. 39, No. 4).

[Problems to be solved by this invention] By the way, in the case of NTSC color video signals, the third
As shown in Figure A, the band of the luminance signal Y is 0 to 4.2 MI
Iz, and the color subcarrier frequency is fs (Gd2.5
8MH2), the band of the carrier color signal C is fs+
0.5MHzfs 1.5MH2 (B in the figure indicates a burst signal).

However, in V 'l' H of the color under type, sufficient +lf is needed for the low frequency converted carrier color signal.
Therefore, the band of the recorded and reproduced carrier color signal C is approximately fs±0.5 MHz.

Therefore, when a color video signal is recorded and reproduced using V'1'H of the color under type, the color resolution will be lowered.

On the other hand, V 1'R for professional use uses a direct method, in which the color video signal is directly converted into an FM signal for recording and reproduction, so there is no drop in color resolution.

However, when recording and reproducing using the direct method with a home V 'l' R, a drop in S/N and moiré occur due to reasons such as a lack of recording and reproducing bandwidth.
It's not practical.

Therefore, the applicant proposed a method for recording and reproducing color video signals that solved these problems (Japanese Patent Application No. 62-6292
The invention proposed earlier converts the luminance signal and the subject area component of the carrier color signal into an FM signal. The data is converted and recorded and played back.

Figure 4 shows the recording system of the one proposed earlier, in which the color video signal (Y+C) shown in Figure 3A is input to the input terminal (11
) is supplied to a subtraction circuit (13) through an AGC circuit (12), and is also supplied to a C-shaped comb filter (21), where a carrier color signal C having a burst signal B is extracted as shown in FIG. , this signal C is supplied to a bandpass filter (22) to limit the band, and as shown in FIG. Low frequency component CL
(Strictly speaking, the narrowband component modulated by the low frequency component of the color difference signal modulating the signal C) is extracted, and this signal CL is supplied to the subtraction circuit (13) through the switch circuit (18). Ru.

In this case, the switch circuit (18) is turned on during the non-burst period and turned off during the burst period by the burst flag.

Therefore, during the non-burst period, the signal cL is subtracted from the signal (Y + C) in the subtraction circuit (13), so that the subtraction circuit (13) outputs the luminance signal Y and The sum signal (Y+Co) of the western component CM of the carrier color signal C (strictly speaking, the outer band component of the signal C that is modulated by the high frequency component of the color difference signal) is extracted, and is added during the burst period. Since subtraction is not performed in the subtraction circuit (13), E
As shown in , a luminance signal Y (hereinafter referred to as Y (B)) having a burst signal B is extracted.

Then, the signal (Y+CM) from this subtraction circuit (13)
The signal Y (B) is supplied to the FM modulation circuit (15) through the pre-emphasis circuit (14) and is converted into the I''M signal SP distributed on the high frequency side as shown in F in the same figure, and this signal Sp is It is supplied to the adder circuit (16).

Moreover, the signal C from the bandpass filter (22) is
Frequency converter (24) through ACC circuit (23)
is supplied to the AFC/APC circuit (
25) to frequency (fs+fc) (for example, fc=
An alternating signal of 43.75fH (Q6688kHz, f14 is the horizontal frequency) is supplied to the converter (24), and the low frequency component C is converted to 1iiJ. As shown in , the color subcarrier frequency is frequency-converted from a frequency fs to a signal with a frequency fc, and this converted signal CL is sent to an adder circuit (16).
supplied to

Therefore, as shown in FIG. It will be done.

Then, this signal (SP +CL) is transmitted to the recording amplifier (1
7) to the rotating magnetic head (IA) (IB).

These heads (IA) and (1B) are 801
, and a servo circuit (not shown) provides a signal Y
is rotated at the frame frequency in synchronization with
A magnetic tape (2) is wound diagonally around the rotating circumferential surface over an angular range of just over 80 degrees, and is run at a predetermined speed.

Therefore, tape (2) contains the signal (SP+CL)
are sequentially recorded as one diagonal magnetic track with a guard band for each field period.

On the other hand, Fig. 5 shows the silk thread, and the servo circuit (not shown)
The head (IA) for the track of tape (2)
, (1B) are performed, and a signal (SF +CL) is taken out from the heads (18) and (IB). However, in this case, this signal (SP +
There is jitter in the signals Y, CH, and Ct in CL), and each synchronization frequency is a jittery frequency fH'', fs'', fc' from the normal frequency [HIs fc.

to 7 F (IA), playback signal from (1B) (
Sp CL) is supplied to a band pass filter (32) through a reproducing amplifier (31) to extract a signal Sp, which is supplied to an FM demodulation circuit (34) through a limiter (33) and is used in a non-burst period. is the signal (Y+
CH) is demodulated, and during the burst period, signal Y (B) is demodulated, and these signals (Y+CM) and signal Y (B)
is supplied to the parse I/signal removal circuit (36) through the de-emphasis circuit (35).

This burst signal removal circuit (36) is controlled by a burst flag and sets the burst period to a pedestal level and removes the burst signal. Therefore, only the signal (Y+CM) is taken out from this burst signal removal circuit (36). Note that this signal (Y+CM) has jitter as described above, and each synchronization frequency is the frequency f♂fs''.

Further, the signal (SF + CL) from the amplifier (31) is supplied to the low-pass filter (41), and the low-frequency component CL of the carrier color signal C (the C color subcarrier frequency is [C'') is extracted. The frequency B (fs″′+
The alternating signal Sa of FC") is supplied to the converter (43), and the signal CL has a carrier frequency fc'" which is a carrier frequency rs.
This frequency-converted signal CL is supplied to the adder circuit (37).

Therefore, in the adder circuit (37), the signal (Y+C
M) and signal CL are added, so the addition circuit (37)
The original color video signal (Y+C) is extracted from. However, this signal (Y + C) has jitter, and each synchronization frequency is frequency fH'''', fs''''.

Then, the signal (Y + C) is supplied to the THC (3B), the time axis is corrected, and the original color video signal (Y + C) without jitter is taken out at the terminal (39).

In this case, the high frequency component CM and low frequency component CL of the carrier color signal need to be combined in a state where they have the same amount of jitter. For this reason, the above-mentioned alternating signal Sa is for up-converting the low-frequency component CL by adding the same amount of jitter as the high-frequency component CM.
APC circuit (50).

(60) as follows.

That is, No. 16 (Y+CH) and signal Y (B) from the de-emphasis circuit (35) are sent to the sync separation circuit (51).
) is supplied to A F
The signal is supplied to the C/A PC circuit (50).

Further, at this time, the signal (Y+Cl4) and the signal Y (B) from the de-emphasis circuit (35) are supplied to the burst gate circuit (52), and the frequency f having jitter is supplied to the burst gate circuit (52).
The burst signal B of s''' is taken out, and this burst signal B is supplied to the ANC/APC circuit (50).

Then, from this ANC/APC circuit (50), a signal Ss with a frequency fs", which has jitter in synchronization with the pulse PH and is synchronized with the burst signal B, is obtained. In other words, this signal Ss is the de-emphasis circuit (3
5) becomes a signal with a frequency [S'' and a phase having jitter corresponding to the jitter of the signal (Y+CH).

This signal Ss is then supplied to the frequency converter (44).

In addition, No. 14 (Y
+CH) and signal QY are supplied to a synchronization separation circuit (61), horizontal synchronization pulse circle 1 of frequency fHII having jitter is taken out, and this pulse PH is supplied to an AFC/APC circuit (60).

Furthermore, at this time, fA C from the converter (43)
L is supplied to a burst gate circuit (62), a burst signal B having a frequency fs'' having a thick is taken out, and this burst signal B is supplied to the AFC/APC circuit V& (60).

Then, from this A N C/A P C circuit (60), a frequency fc' which has jitter in synchronization with the pulse PH and is synchronized with the burst signal B obtained from the low frequency component CL is output.
A signal Sc of
44).

Therefore, frequency addition of the signal Ss and the signal Sc is performed in the converter (44), and an alternating signal Sa having a jitter at a frequency (fs''+fc') is taken out from the converter (44).

Using this signal Ss, the frequency of the signal CL is converted in the converter (43) as described above.

Therefore, in response to the signal CL from the converter (43), the AFC/APC circuit (50) converts the synchronization signal P of the output signal q(Y+CH) of the de-emphasis circuit (35).
Based on I41113, the AFC/APC circuit (60) outputs the synchronizing pulse PH in the output signal of the de-emphasis circuit (35) and the output signal of the converter (43). Since the AFC/APC operation is performed based on the burst signal B, the signal (Y+CH
) and signal CL have the same jitter, and from the adder circuit (37), the high frequency component C
The original carrier color signal C, in which the H and low frequency components CL are correctly combined, and the luminance signal Y are extracted.

In this manner, according to the present invention, the high frequency component CH of the luminance signal Y and the carrier color signal C is converted into the t'M signal SF, and the low frequency component CL of the carrier color signal C is converted to a frequency lower than the FM signal Sp. A frequency multi-vehicle signal (SF +C) of the low frequency signal CL and the FM signal Sp
L) is recorded, and the reverse process is performed during playback, so the recording and playback bandwidth for the carrier color signal C becomes wider, and all band components of the carrier color signal C can be recorded and played back. There is no low pitch.

In addition to the luminance signal Y, the high frequency component C of the carrier color signal C
Although M is converted into an FM signal, the energy of the high-frequency component Cs is small, so there is no reduction in S/N or moiré as in the case of the direct method.

Furthermore, since the low-frequency component CL of the low-pass converted carrier color signal C has a narrower bandwidth than the low-pass converted carrier color signal in a general color under system, the FM signal S
The bandwidth of P can be widened, the resolution is higher,
A luminance signal Y with a good S/N ratio can be obtained.

Further, the change is small compared to a general color under-one type VTR, and furthermore, it can handle so-called high-quality color video signals.

In the example shown in FIG. 4, a switch circuit (18) is provided, which is turned off only during the burst signal period, and the subtraction circuit (13) is turned off only during the burst signal period.
Although the burst signal B is also taken out from the output of the output, the following arrangement may also be made.

That is, the switch circuit (18) is not provided, the burst signal is not extracted from the subtraction circuit (13) during the burst period, and the burst signal B is extracted from the output of the bandpass filter (22) and supplied to the PLL. , a pilot burst signal PH1 which has a certain frequency ratio relationship with the burst signal B at frequency f3 or lower and is synchronized with the burst signal B, for example, a pilot burst signal with a frequency of fs/2 is obtained, and this signal PH is sent from the subtraction circuit (13). It may be added to the signal (Y+(, I4)).

In this case, in the reproduction system, the pilot burst signal PB is obtained by the burst gate circuit (52), and the output signal of the variable frequency oscillation circuit is divided into a frequency equal to that of the signal PB in the AFC/APC circuit (50). It is a good idea to compare the phases of the two.

Incidentally, in the above-mentioned recording and reproducing apparatus, it is assumed that the human-powered color video signal to be recorded has a constant phase relationship between the luminance signal and the carrier color signal, like a television broadcast signal.

However, the conventional color under one-way V 'I' H
In the case of the reproduced color video signal, the conveyed color signal becomes a jitter-free signal due to the AFC/APC circuit of the reproduced yarn, while the luminance signal remains a signal with a thick component. The phase relationship between the two is not constant. Therefore, when this signal is recorded and reproduced using the method described above, the luminance signal and carrier color signal are reproduced with their phases not having a constant relationship, just as they were during recording. Ru. If this is stabilized with l'HG based on the carrier color signal, jitter will remain in the luminance signal, while on the other hand, if it is stabilized with rBC based on the luminance signal, the color subcarrier frequency fs will change, and the reproduced image will have no color. I can't stand it anymore.

The present invention aims to provide a recording apparatus that does not suffer from the above-mentioned drawbacks even when a human color video signal is a signal in which the phase relationship between the luminance signal and the carrier color signal is not constant.

Means for Solving the L Problem In this invention, means (72) (73) (7
4), means (71) (75) for adding the same amount of jitter as the luminance signal Y to the high-frequency component CH of the carrier color signal, and means (75) for adding the high-frequency component CH to which the jitter amount has been added to the luminance signal Y. 1 addition means (65) and this first addition means (65);
Modulation means (67) for frequency modulating the added output from 5)
, frequency conversion means (71) (73) for frequency converting the low frequency component CL of the carrier color signal to the low frequency side of the frequency modulation signal output from the addition means (65), and the output and frequency of the modulation means (67). a second addition means (68) for adding the outputs of the conversion means (71) and (73);
Means (IA) for recording the output of 8) on the recording medium (2)
(1B) is provided.

[Effect]

The high-frequency component CM of the carrier color signal that is added to the luminance signal Y and subjected to de-M modulation has the same jitter as the luminance signal Y, so if it is reproduced by the reproduction system shown in FIG. 5, for example, 'r
By BC, jitter is removed from both the luminance signal Y and the carrier color signal C, and a good reproduced image can be obtained.

(Embodiment) Fig. 1 shows an example of the device of the present invention, and (61) is an input terminal for a color video signal.
61), the luminance signal is a signal Y having jitter, such as the V '1' H reproduction signal of the conventional color under one-way system.
(f♂), but the carrier color signal is a jitter-free signal and a color video signal (fs) composed of a composite signal (see frequency characteristics in Figure 2 A) is supplied as an example. do.

In this case, as is clear from FIG. 2A, the frequency band of the carrier color signal is from fs -0.5 to fs + 0.5 MH.
It is z.

The human color video signal through this input terminal (61) is A
In the example shown in Figure 0, which is supplied to the Y/C separation circuit (63) via the GC circuit (62), this Y/C portion lll1i! The circuit (63) uses a comb-shaped filter consisting of a delay circuit (631) of one horizontal period, an addition circuit (632), and a subtraction circuit (633), but it can also be constituted by a bandpass filter or a bypass filter and a lowpass filter. You can also do that.

A luminance signal Y (fH'') is obtained from the addition circuit (632) of this Y/C separation circuit (63), and this
The signal is supplied to the adder circuit (64) with the burst burst signal PB. For this example, the pilot burst (114PH) is obtained as follows.

That is, the output signal of the AGC circuit (62) is supplied to the synchronization separation circuit (91), which outputs the horizontal synchronization signal H(f/
) is obtained and supplied to the phase comparison circuit (102). On the other hand, a variable frequency oscillation circuit (hereinafter referred to as vCO) (103) whose free-running oscillation center frequency is twice the color subcarrier frequency fs is provided.
) (7) The output signal is divided into 1/4 by the frequency dividing circuit (104)
55 to produce a horizontal frequency signal, which is supplied to the phase comparator circuit (102) and output as a horizontal synchronizing signal H (fH1'').
The phase is compared with This phase comparator circuit (102
) is passed through a low-pass filter (105) to vCO
(103), whose oscillation frequency has the same jitter as the horizontal synchronization signal) 1 (fH#l) 2fs
”.

Then, the output signal of this VCO (103) is transferred to the frequency dividing circuit (
106) to obtain a signal with a frequency fs'', which is supplied to an adder circuit (64) as a pilot burst signal PR.

The sum signal of the luminance signal and the pilot burst signal PR from this adder circuit (64) is supplied to an adder circuit (65).

On the other hand, a carrier color signal C (fs) is obtained from the subtraction circuit (633) of the Y/C separation circuit (63), which is supplied to the frequency converter (71) and subjected to low frequency conversion.

The frequency conversion signal supplied to this converter (71) is formed as follows.

That is, the output signal of the AGC circuit (62) is supplied to the burst gate circuit (e), thereby obtaining the reverse signal B (fs), which is supplied to the phase comparison circuit (82). On the other hand, a variable frequency crystal oscillation circuit (hereinafter referred to as VXO) (83) whose oscillation center frequency is Is is provided,
The output signal of this VXO (83) is sent to the phase comparator circuit (82).
is supplied to the burst signal B(fs) and compared in phase with the burst signal B(fs). The phase comparison output is then filtered through a low-pass filter (84
) is supplied to the vXO (83) via the VXO (
83), an alternating signal S1 of frequency fs synchronized with the burst signal B is obtained, and this is supplied to the frequency converter (85).

Further, a horizontal synchronization signal H(f)/l) having jitter is supplied from the synchronization separation circuit (91) to a phase comparison circuit (92). On the other hand, VCo (93) with a free-running center frequency of 175 fH
1. :, <7) The output signal of the VCO (93) is divided by 1/175 by the frequency divider circuit (94) to produce a signal with a horizontal frequency fH, which is then sent to the phase comparator circuit (94).
2), and the phase is compared with the horizontal synchronizing signal H.

Then, the phase comparison output is passed through a low-pass filter (95)
is supplied to the VCO (93) via the VCO (93).
), frequency 1 has the same jitter as the horizontal synchronization signal H.
An alternating signal S2 of 75fH1 is obtained, which is passed through the frequency divider circuit (
96), the frequency is divided by 1/4 and the frequency is 175/4.
An alternating signal S3 of f 14''=fc'' is obtained, and this alternating signal S3 is supplied to a frequency converter (85). Then, from the frequency converter (85), the frequency fs+f
An alternating signal s4 of "c" is obtained, which is supplied to the frequency converter (71).

be done.

In the converter (71), the carrier chrominance signal C (fs) is converted to a low frequency by changing the color subcarrier frequency from fs to fc'' having jitter by this alternating signal s4.This low frequency converted carrier chrominance signal is Relatively wide bandpass filter (
72) and from this, as shown in FIG. 2B, f
A carrier color signal C (fc″) in a band of c −0.5 to fc+0.5 MHz is obtained. This broadband carrier color signal C
(fc”) is supplied to the subtraction circuit (74), and
It is supplied to a narrow band band pass filter (73) similar to the band pass filter (22) in the example in FIG. 4, and from this band pass filter (73) fc±
A low frequency component CL of the Ill color sending signal of 0.3 Mtlz is obtained. Then, this low frequency component CL is converted to a subtraction circuit (74).
subtracted from the carrier color signal C(fc″);
From this circuit (74), the gamut component CH(fc') of the carrier color signal as shown in the second diagram is obtained. This high frequency component CM is supplied to a frequency converter (75).

Also, the frequency f with jitter from the frequency dividing circuit (96)
The signal S1 of "c" and the signal of frequency fs" having jitter from the frequency dividing circuit (106) are transferred to the frequency converter (97).
), and the frequency fs is supplied from this converter (97).
An alternating signal 4) S5 of "+fc" is obtained and supplied to the frequency converter (75). Therefore, a western component having the same jitter as the luminance signal and having a chrominance subcarrier frequency of "fs" is obtained from the converter (75), and this is supplied to the adder circuit (65), as shown in FIG. 2E. It is added to the luminance signal Y and pilot burst signal PR.

The output signal of this adder circuit (65) is pre-emphasized
The signal is supplied to the frequency modulation circuit (67) through the path (66) and converted into FM (i signal Sp), which is then supplied to the addition path (68). The low-frequency component C of the frequency-converted carrier color signal is supplied to the low-frequency side of the M signal SF, and is added to the M multiplication signal Sp (see Figure 2), and the added signal is A rotary magnetic head (IA) similar to the example in FIG. 4 is connected through a recording amplifier (69).

(1B) and recorded on the magnetic tape (2) as diagonal magnetic tracks.

In the above example, the pilot burst signal PR was added, but instead, the subtraction circuit (74)
A switch circuit may be provided between the filter and the bandpass filter (73), and this switch circuit may be turned off only during the burst signal section, leaving the burst signal in the high frequency component CM.

In addition, instead of performing low-frequency conversion on the carrier color signal C and then dividing it into a low-frequency component CL and a surface area component CM, the carrier color signal C is divided into a low-frequency component CL and a high-frequency component CM, and then the low-frequency component CL may be low frequency converted, and the iGb band component CM may be given the same jitter as the luminance signal Y and added to the luminance signal.

In this case, as shown in Figure 5, during playback, the low frequency component CL
is synthesized after making it have the same jitter as the +111jffl component CH, so it is not necessary to give the same jitter as the Ha times signal to the low frequency component CL.

In addition, means for imparting the same amount of jitter as the luminance signal to the low-frequency component is limited to methods that use a frequency converter, such as inverse conversion of '1' BC, demodulating the carrier color signal, and converting it to jitter. A variety of means are used, such as remodulating the color subcarrier with a chromatic subcarrier.

Note that the above description has been made for the case of recording the playback signal of a conventional color under one type VTR, but the idea of this invention is to add the same amount of jitter to the acid component as the luminance signal, so there is no need to have jitter. First, even when recording a color television signal in which a luminance signal and a carrier color signal have a constant phase relationship, recording can be performed without changing the circuit configuration at all.

Incidentally, when recording a reproduction signal of a VTR which outputs a luminance signal and a carrier color signal from separate output terminals, the Y/C separation circuit (63) shown in the example of FIG. 1 can be omitted.

【Effect of the invention〕

As described above, according to the present invention, in a wideband color recording method in which the high frequency component of a carrier color signal is FM modulated and recorded together with a luminance signal, the high frequency component is given the same jitter as the luminance signal, and then the luminance signal is This allows for recording that can be reproduced well, even if it is a conventional color under one-way V 'l'' H reproduction signal or a regular color television signal. The device can be realized.

Moreover, there is an advantage that there is no need to switch between recording a V'l''H reproduced signal and recording a regular color television signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of the inventive device, FIG. 2 is a frequency characteristic diagram for explaining the same, and FIG. 3 is a frequency characteristic diagram for explaining the wideband color VTR proposed earlier.
FIG. 4 is a block diagram of an example of the recording system, and FIG. 5 is a block diagram of an example of the recycled yarn. (65) is the first addition circuit, (67) is the frequency modulation circuit, (68) is the second addition circuit, (71), (75
) is a frequency converter, (72) is a wideband bandpass filter, (73) is a narrowband bandpass filter, (
74) is a subtraction circuit.

Claims (1)

[Scope of Claims] (a) means for dividing the carrier color signal into high-frequency components and low-frequency components; (b) means for imparting the same amount of jitter as the luminance signal to the high-frequency components of the carrier color signal; (c) a first addition means for adding the high-frequency component to which the jitter has been added to the luminance signal; (d) a modulation means for frequency modulating the added output from the first addition means; (e ) frequency conversion means for frequency converting the low frequency component of the carrier color signal to the low frequency side of the frequency modulation signal of the addition output; (f) a frequency conversion means for adding the output of the modulation means and the output of the frequency conversion means; (g) means for recording the output of the second adding means on a recording medium.