JPH0210993A - Chrominance carrier signal processing circuit - Google Patents

Abstract

PURPOSE:To prevent deterioration in the picture quality by superimposing a pilot signal on an input chrominance carrier signal to a comb-line filter and adjusting the phase and level of a retarded chrominance carrier signal depending on the phase and level difference of retarded and non-retarded pilot signal. CONSTITUTION:A chrominance carrier signal C1 outputted form a BPF 6 is fed to a pilot signal superimposing circuit 8 and a chrominance carrier signal C1P surerimposed with the pilot signal is obtained. The chrominance carrier signal C1P is fed to a subtractor 9 and fed to a variable phase shift circuit 19 whose phase shift is varied by a control signal and phase-shifted. Then the signal is retarded by one horizontal synchronizing signal period by a delay element 20 and the level is adjusted by a variable gain circuit 18 whose gain is varied by the control signal and supplied to the subtractor 9 as a retarded carrier signal C1PD. Thus, a chrominance carrier signal C2P whose crosstalk component is eliminated is obtained from the subtractor 9 by the effect of a comb-line filter 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a helical scan type magnetic recording reproducing device (
The present invention relates to a carrier color signal processing circuit (hereinafter referred to as a VTR), and particularly to a carrier color signal processing circuit suitable for reducing noise components of carrier color signals.

[Conventional technology]

Conventionally, in a VTR, the color signal reproduction system removes crosstalk components from adjacent tracks on the magnetic tape and other noise components that are mixed into the reproduced carrier color signal, and the S/
It is known to provide a comb filter to improve N.

FIG. 10 shows an example of a conventional carrier color signal processing circuit provided with such a comb filter (for example, JP-A-62-1!+0
Publication No. 8)'! ! 1 is a block diagram showing a preamplifier, 2 is an Lpr (low-pass filter), 3 is a reproduction luminance signal processing circuit, 4 is an LPF, 5 is a main converter, 6 is a BPF (band-pass filter), and 7' is a comb. 9 is a subtracter, 20 is a delay element, 22 is a BPF
, 23 is a burst gate, 24 is a phase shift circuit, 25 is a sub-converter, 26 is an oscillator, 27 is a VCO (voltage controlled oscillator), 28 is a phase detector, 29 is a loop filter, 3
0 to 32 are input terminals, 33 and 34 are output terminals, 60 is a phase circuit, and 61 is a level adjustment circuit.

In the figure, a reproduction signal from a reproduction head (not shown) is input to an input terminal 30, and after being amplified by a preamplifier 10, a luminance signal is separated by a BPF 20. This luminance signal is processed by the reproduced luminance signal processing circuit 3 and output to the output terminal 34.

On the other hand, the output signal of the preamplifier 10 is supplied to the LPF 4, where a low frequency converted carrier color signal is extracted and supplied to the main converter 5. In the main converter 5, this low-pass converted carrier color signal is returned to a carrier color signal with a subcarrier frequency (hereinafter referred to as f) of 558 MHz in the case of the NTSC system and 4.43 MHz in the case of the PAL system, B.P.
Unnecessary components are removed by F6. Transport color credit output from this BPF6.

includes crosstalk components from adjacent tracks on the magnetic tape, but since this crosstalk component is in a frequency interleaved relationship with the carrier color signal reproduced from the track being reproduced and scanned, it is assumed that one horizontal period (hereinafter referred to as 1H a phase shift circuit 60 for adjusting the phase and amplitude of the carrier color signal (hereinafter referred to as delayed carrier color signal) C9 delayed by the delay element 20, the subtracter 9, and the delay element 20 having a delay amount of The crosstalk component is removed by the comb filter 7 comprising the level adjustment circuit 61, and the subtracter 9 obtains a carrier color signal C2 free of crosstalk components. This carrier color signal C2 is output from the output terminal 35.

Here, the phase shift circuit 34 combines the carrier color signal C1 outputted from the BPF 6 and the delayed carrier color signal C1D produced by the delay element 20.
is input to the subtracter 9, the phase of the delayed carrier color signal C1D is adjusted so that the crosstalk component mixed in the carrier color signal C1 is sufficiently attenuated. Further, the level adjustment circuit 35 similarly performs the following in the subtracter 9:
The level of the delayed carrier color signal CjD is adjusted so that the crosstalk component in the carrier color signal C1 is sufficiently attenuated.

The carrier color signal processing circuit also includes an A P C (Automatic PhaC) in order to stabilize the phase of the carrier color signal C1 during frequency conversion in the main converter 5.
seContral ) circuit is provided.

That is, the carrier color signal 02 output from the comb filter 7 is supplied to the burst gate 25, and a burst signal is extracted by a gate pulse formed by a horizontal synchronization signal input from the input terminal 62. This burst signal is supplied to the phase detector 28, and the oscillator 2 oscillates at a frequency fl10 equal to the subcarrier frequency of the standard method.
Phase detection is performed using the output signal of 6, and the detected output is supplied to the VCO 27 via the loop filter 29. As a result, the VCO 27 oscillates in phase synchronization with the burst signal of the carrier color signal C2.

The center oscillation frequency of the VCO 27 is set to the subcarrier frequency of the low frequency conversion carrier color signal from the LPF 4, and
Taking millivideo as an example, in the case of NTSC system, it is 378
fI! (However, f8 is the frequency of the horizontal synchronization signal), PAL
In the case of the method, it is 375 f.

The output signal of VCO 27 is supplied to phase shifter 24VC.

This phase shifter 24 receives a horizontal synchronizing signal from an input terminal 32,
A vertical synchronization signal from the input terminal 31 switches the amount of phase shift every 1H. As a result, in the case of the NTSC system, the phase is shifted by 180° every 1H, and the phase shift direction is reversed every 1 field. In addition, in the case of PAL system, 1
The phase is shifted by 90 degrees every H, and the phase shift direction is reversed every field.

The low-pass conversion carrier color signal output from the LPF 4 is also phase-shifted, and the output signal of the phase shift circuit 24 is phase-synchronized therewith.

The output signal of the phase shift circuit 24 is frequency-converted by the sub-converter 25 using the output signal of the oscillator 26, and the BPF 22
A signal having a frequency that is the sum of the frequencies of these output signals is extracted and supplied to the main converter 5. In the main converter 5, the frequency of the low frequency conversion carrier color signal is converted using this signal, and the subcarrier frequency f is output from the BPF 6.
,. A carrier color signal C4 is obtained.

[Problem to be solved by the invention]

Incidentally, in order to ensure the performance of the comb filter 7, the phase shift amount of the phase shift circuit 60 and the characteristics of the level adjustment circuit 61 must be set accurately. In this setting, a test signal having the same frequency spectrum as the luminance signal is supplied to the square filter, and the phase shift circuit 60 and level adjustment circuit 61 are manually adjusted so that the output signal thereof becomes zero.

However, since it normally requires considerable skill to perform this adjustment with high precision, when such adjustment is performed at the manufacturing stage of the VTR, it is unavoidable that variations in adjustment will occur. Furthermore, even if the adjustment is made with high precision, once the adjustment is completed, these phase shift circuits 6
0. Since the means for adjusting the characteristics of the level adjustment circuit 61 are fixed, these characteristics change due to changes in ambient temperature, etc., and it is not possible to always ensure sufficient performance of the comb filter. For this reason, there is a problem that the quality of the reproduced image deteriorates.

By the way, in order for the comb filter 7 to sufficiently remove the crosstalk component C0 that is frequency-interleaved with the carrier color signal C1, the comb filter 7' must be able to remove the carrier color signal component C0 as shown in FIG. It is necessary to have a frequency characteristic in which the maximum passing characteristic is obtained at C0, and the maximum attenuation characteristic is obtained at the cross component C0.

However, if the phase adjustment by the phase shift circuit 60 is inappropriate, as shown in FIG. 12, and if the level adjustment by the level adjustment circuit 51 is inappropriate, the first
As shown in FIG. 3, the crosstalk component C0 is not sufficiently attenuated, and the crosstalk C component remains in the carrier color signal C2 output from the comb filter 7', causing image quality deterioration.

Furthermore, since each adjustment is done manually, there is also the problem that reductions in product costs are hindered.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording and reproducing device that eliminates such problems, eliminates the need for manual adjustment of the comb filter, and always ensures the best performance of the comb filter. It is in.

[Means to solve the problem]

To achieve the above object, the present invention provides means for superimposing a pilot signal on an input carrier color signal of a comb filter;
Means for generating a phase shift control signal according to a phase difference between a non-delayed pilot signal that does not pass through a delay element and a pilot signal in a carrier color signal delayed by the delay element, and a level of the non-delayed pilot signal and the delayed pilot signal. means for generating a level control signal according to the difference; means for adjusting the phase of the delayed carrier color signal whose phase shift amount is controlled by the phase shift control signal; and means for adjusting the phase of the delayed carrier color signal whose gain is controlled by the level control signal; and means for adjusting the level of the color signal.

[Effect]

The phase of the non-delayed pilot signal and the delayed pilot signal,
The level relationship represents the phase and level relationship between the input carrier color signal and the delayed carrier color signal, respectively. Therefore, by detecting the phase difference and level difference between these pilot signals and adjusting the phase and level of the delayed carrier color signal accordingly, when subtracting the input carrier color signal and the delayed carrier color signal in the subtracter, K, which suppresses noise components such as crosstalk components mixed into the carrier color signal due to frequency interleaving, and the phase and level relationships between the input carrier color signal and the delayed carrier color signal are automatically set.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an implementation eA of a carrier color signal processing circuit according to the present invention.
7 is a block diagram showing a comb filter; 8 is a block diagram showing a comb filter;
is a pilot signal superimposition circuit, 10.11 is a pilot gate, 12 is a 90° phase shifter, 15 is a phase detector, 14 is an LPF', 15 is a detector, 16 is an LPF, 17 is a comparator, and 18 is a variable gain circuit. , 19 is a variable phase shift circuit, 21 is a pilot signal removal circuit, 35 is a detector, and 36 is an LPF, and the parts corresponding to those in FIG. 10 are given the same reference numerals and redundant explanations will be omitted.

In the figure, a carrier color signal C4 output from BPF6
is supplied to a pilot signal superimposing circuit 8, where the pilot signal is superimposed to obtain a carrier color signal C1.

Here, the process of superimposing the pilot signal in the pilot signal superimposing circuit 8 to generate the carrier color signal C1 is described as a second process.
This will be explained using figures.

Frequency f, which is continuously output from the oscillator 26.

The signal SQ is also supplied to the pilot signal superimposition circuit 8. In the pilot signal superimposition circuit 8, the pulse period of the horizontal synchronizing signal H8 supplied from the input terminal 32, the carrier color signal C
The output signal 5o) of the oscillator 26 is output at the time of 1.

From this K, the carrier chrominance signal C4 receives the output signal S of the oscillator 26 during the period corresponding to the horizontal synchronizing signal of the horizontal retrace period. is superimposed as a pilot signal.

However, the oscillation frequency, superimposition position, and superimposition period of the pilot signal may not be specified in FIG. 2 and may be arbitrary.

Carrier color signal C output from pilot signal superimposition circuit 8
1 is supplied to the subtracter 9, and is also supplied to the variable phase shift circuit 19 whose phase shift amount is changed according to the control signal, where the phase is shifted, and after being delayed by 1H by the delay element 20, the control signal is The signal is level-adjusted by a variable gain circuit whose gain is changed, and is supplied to the subtracter 9 as a delayed carrier color signal C41. As a result, the subtracter 9 outputs the carrier color signal C from which crosstalk components have been removed due to the effect of the comb filter 7.
2P is obtained.

Here, the delayed carrier color signal CI in the variable phase shift circuit 19
Phase adjustment of PD will be explained.

First, at the pilot gate 10, the pilot signal Ps is extracted from the carrier color signal CAF using the horizontal synchronization signal H8. Similarly, the pilot gate 11 extracts the pilot signal P from the delayed carrier color signal C41.

The pilot signal P is phase-shifted by 90° by a 90° phase shifter 12, and its output pilot signal PDs is phase-compared with the pilot signal PS by a phase detector 13. Phase detector 13
The phase detection signal PhD output from the variable phase shift circuit 19 is smoothed by the LPF 14 and supplied to the variable phase shift circuit 19 as a phase shift control signal Pho that controls the amount of phase shift of the variable phase shift circuit 19. The variable phase shift circuit 19 shifts the phase of the carrier color signal CIF by an amount corresponding to the phase shift control signals P, , Ic, and supplies it to the delay element 20 .

In this process, the amount of phase shift in the variable phase shift circuit 19 is determined by the phase shift control signal P5. controlled by This process will be explained with reference to FIGS. 3, 4, and 5.

FIG. 3 shows the pilot signal P8 when the phase difference between the carrier color signal C1P and the delayed signal C11 is exactly 180° by using a delay element 20 that can accurately delay IH (2H in the PAL system). 90° phase shifter output signal PI
)8 shows the relationship between the output signal PhD of the phase detector 16 and the phase shift control signal phc.

Due to variations in the delay amount of the delay element 20, the carrier color signal C
When the phase difference between 1F and the delayed carrier color signal C41 is not 180°, the phase shift amount of the variable phase shift circuit 19 is controlled,
The adjustment is made so that the phase difference is 0°, and this process will be explained.

First, the conveyed color signal CIP is delayed conveyed color signal C11, and 1.
There is an 80° phase difference, and by further shifting the phase of the pilot signal pIl'iQo of the delayed carrier chrominance signal CjPD, the pilot signal P8 and the output signal p of the 900 phase shifter 12 are
The phase relationship of as is shown in FIG.

When the phase detector 13 is configured with an exclusive OR circuit, the output signal PhD of the phase detector 13 at this time becomes a signal with a duty ratio of 50% at 1/2 period of the pilot signal P3, as shown in FIG. , the phase shift control signal phc obtained by smoothing it with the 1LPF 14 is the output signal P1. of the phase detector 13. The voltage signal is the average potential of . In the phase shift control signal phc of such a potential, the phase shift control signal - shown in FIG.
A variable phase shift circuit 19 having a phase shift amount characteristic transfers the carrier color signal cap
The phase of the signal is not shifted, and the phase is passed as it is. this is,
This is because the delay amount of the delay element 20 is 1H and the phases of the input and output signals differ by 180°, and in this case, there is no need for phase adjustment.

Next, since the delay amount of the delay element 20 is larger than 1H, the delay signal C11 is 180° larger than the carrier color signal CIP.
A case in which the delay is greater than that will be explained using FIG. 4(a).

In this case, the pilot signal PD3 is extracted from the delayed carrier color signal C11 and phase-shifted by the 90° phase shifter 12.
is delayed with respect to the pilot signal P than in the case of FIG. As a result, the high level period of the output signal of the phase detector 13 becomes narrower than in the case of FIG. 3, and the potential of the phase shift control signal Pho obtained from the LPF 14 is The potential is lower than that of the signal Pho. This phase shift control signal Phc causes the variable phase shift circuit 1
9 is controlled to advance the phase of the carrier color signal t"P+ based on the phase shift control signal-phase shift amount characteristic shown in FIG. 5. As a result, the delayed carrier color signal C11, The phase delay is removed, and the phase difference with the carrier color signal ctp becomes 180°.

Further, a case will be described with reference to FIG. 4(b) in which the delay amount of the delay element 20 is smaller than 1H, so that the delayed conveyance color signal C11 advances further than the conveyance color signal CIP.

In this case, the pilot signal PDS is extracted from the delayed carrier color signal C51 and phase-shifted by the 90° phase shifter 12.
will proceed with respect to the pilot signal PsVc more than in the case of FIG. In this case, the output signal PhD of the phase detector 16 has a longer period of high level υ than in the case of FIG. P. The potential is higher than that.

This phase shift control signal Pho controls the variable phase shift circuit 19 to delay the phase of the carrier color signal t"P2. As a result, the phase lead of the delayed carrier color signal C41, is removed, and the carrier color signal CjP The phase difference with that is 1800.

As a result of the above, the frequency characteristics of the comb filter 7 in which the maximum point of attenuation as shown in FIG. 12 is shifted from the frequency at which the crosstalk component Cc is located are as shown in FIG.
The characteristics are adjusted to those that can best attenuate the crosstalk component C6.

Next, the adjustment of the amplitude level of the delayed carrier color signal CIP by the variable gain circuit 18 will be explained.

In FIG. 1, pilot signals P8. P, is envelope-detected by the wave detector 15, smoothed by LPFl 6.35, and becomes each pilot signal P9. Level fluctuation signal PIL + indicating amplitude level fluctuation of PD by rectified voltage fluctuation
"DI" is formed.These level fluctuation signals P!I
L+PDL is input to comparator 17. The formation process of these level fluctuation signals "8L r PDL" is explained in the sixth section.
Figure (a).

Shown in (b).

The comparator 17 compares the voltage of the level fluctuation signal ppr, which indicates the amplitude level of the delayed carrier color signal C11, with the voltage of the level fluctuation signal P8L as a reference, and uses the output signal as a level control signal, which has a variable gain as c. Supplied to circuit 18.

The variable gain circuit 1B adjusts the amplitude level of the pilot signal P according to this level control signal c.
The amplitude level of the output signal of the delay element 20 is controlled by K so that it is equal to the amplitude level of s.

Here, examples of the input/output characteristics Q of the comparator 17 and variable gain circuit 18 that perform such level control are shown in FIGS. 7 and 8.
The level control operation will be explained with reference to the figure.

As shown in FIG. 7, the comparator 17 receives the level fluctuation signal p
From the potential difference between sLl p and L, "DL = "SL 0
Lac = Q”ox, < Pgl, L@C= PI
IL PDLPDL > Psll-+Lec =
Level control signals related to PSL and PDL. Output c. Further, the variable gain circuit 18 is set to Lo as shown in FIG. The gain changes as follows: =0→(gain)=O Lec >o→(gain)>OL,c×O→(gain)<0.

The comparator 17 and variable gain circuit 18 are shown in FIG.

By having the characteristics shown in FIG. 8, when the amplitude level of the delayed carrier color signal C41 is smaller (larger) than the amplitude level of the carrier color signal CUt, the comparator 17 outputs a positive (
A level control signal (negative), c, is supplied to the variable gain circuit 18, and for this purpose, the variable gain circuit 18 has a positive (negative) gain to control the amplitude of the delayed carrier color signal, c, I'D. Controlled to increase (decrease) the level.

As a result, the amplitude level of the delayed carrier color signal CI FD becomes equal to the amplitude level of the carrier color signal CIF.

That is, from FIGS. 6(a) and 6(b), the level fluctuation signal PDI.

is smaller than P9L by ΔL, and the delayed conveyance color signal C11
, is smaller than the carrier color signal C1 by ΔL, the comparator 17 inputs the level control signal ``eC'' of t to the variable gain circuit 18, as shown in FIG. , whereby the gain becomes 1 and the variable carrier color signal C11, is amplified and controlled to have an amplitude level equal to that of the carrier color signal C+F.Thereby, the carrier color signal CIP input to the subtracter 9 and the delayed Carrier color signal C1PD
have the same amplitude level. As a result, the comb filter 7 reduces the crosstalk component C9 from the frequency characteristic (Fig. 3) in which the amount of attenuation of the crosstalk component C6 is insufficient due to the difference in the amplitude levels of the carrier color signal CAF and the delayed carrier color signal C11. The frequency characteristics are automatically adjusted to provide sufficient attenuation (Fig. 11).

FIG. 9 is a block diagram showing another embodiment of the carrier color signal processing circuit according to the present invention, in which 37 to 39 are input terminals;
0 is a pilot signal superimposition circuit, 41°42 is a switch,
43 is a phase shift control signal holding circuit, 44 is a level control signal holding circuit, 45.46 is a switch, 47 is a BPF, 48 is a main converter, 49 is an LPF, 50 is a phase detector,
51.52 is a VCO 153 is an AFC processing circuit, 54 is a phase shifter, 55 is a sub-converter, 56 is a BPF, 57.5
8 is an output terminal, 59 is an input terminal, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In the embodiment described in FIG. 1, the phase adjustment and level adjustment of the comb filter 7 provided in the reproduction system of the carrier color signal processing circuit are performed on the carrier color signal CIP by the pilot signal superimposition circuit 8 provided in this reproduction system. With the superimposed pilot signal,
However, in the embodiment shown in FIG. 9, a pilot signal superimposition circuit 40 is provided in the recording system of the carrier color signal processing circuit, and the pilot signal superimposed on the carrier color signal C4R allows This is used to adjust the phase and level of the comb filter 7 in the reproduction system.

Here, in the VTR using the embodiment shown in FIG. 9, in addition to specifying the playback mode, the short-term recording mode is first set, during which the phase adjustment and level adjustment of the comb filter 7 are performed, and then the playback mode is set. Although the mode is set, in the comb filter 7, the characteristics of the variable phase shift circuit 19 and the variable gain circuit 18 are maintained as those adjusted in the recording mode.

Next, the entire operation of this embodiment will be explained.

In FIG. 9, when the reproduction mode is designated, first, switches 41, 42, 45, 46 are closed to the R side.

A carrier color signal C1 is inputted from an input terminal 37, and a horizontal synchronization signal is inputted from an input terminal 39, respectively. This burst signal of the carrier color signal C4 and the output signal S of the VCO 51. are compared in phase by a phase detector 50, and these phase difference signals determine V
CO51 is controlled. Therefore, the output signal S of the VCO 51. has the same subcarrier frequency f'sc as the carrier color signal C4, and is phase-synchronized with the burst signal.

The carrier color signal C1 is supplied to the pilot signal superimposition circuit 40, and the horizontal synchronization signal from the input terminal 59 causes the VCO5
1, the output signal S, is as in the embodiment shown in FIG.
Superimposed as a pilot signal.

The carrier color signal CAR output from the pilot signal superimposition circuit 40 is supplied to the comb filter 7 via switches 41 and 42. The comb filter 7 is an LPF 14,
The first stage except that a phase shift control signal holding circuit 43 and a level control signal holding circuit 44 are provided at the next stage of the comparator 17, respectively.
It has the same configuration as the comb filter 7 in the figure,
The phase shift control signal outputted from the LPF' 14 by the pilot signal superimposed on the supplied carrier color signal CIA is sent to the phase shift control signal holding circuit 43, and the level control signal outputted from the comparator 17 is sent to the level control signal. Holding circuit 44
are held respectively. The amount of phase shift of the variable phase shift circuit 19 is controlled by the phase shift control signal held by the phase shift control signal holding circuit 43, and the gain of the variable gain circuit 18 is controlled by the level control signal held by the level control signal holding circuit 44. controlled.

In this way, the comb filter 7 receives the carrier color signal Cj
The characteristics are set as shown in FIG. 11 by the pilot signal superimposed on R. The carrier color signal output from the comb filter 7 passes through switches 45 and 46, and is passed through the BPF.
In 1947, the main converter 48 and LPF 49 performed recording processing to generate the low frequency conversion carrier color signal 02P, but the head switch (not shown) was switched to the reproduction side, and therefore recording was not performed. Not possible.

When a set period (which can be set arbitrarily) has elapsed, the playback mode is set and the switches 42 and 45 are switched to the P side.

Although not shown, the reproduced low frequency conversion carrier color signal is the first
It is returned to the carrier color signal CIP of subcarrier frequency f3c by an APC circuit similar to that in the figure, and is returned to the input terminal 38.
is supplied to the comb filter 7 via a switch 421. As will be described later, this carrier color signal CAF is superimposed with a pilot signal K during recording, and from this K, the comb filter 7 is set to have the characteristics shown in FIG.
Crosstalk component C6 in carrier color signal CAP is removed. Carrier color signal C2 output from comb-shaped filter 7
F passes through the switch 45 and is supplied from the output terminal 58 to a pilot signal removal circuit (not shown) to remove the pilot signal.

In the comb filter 7, when the reproduction mode is set and the supply of the carrier color signal CIF is started, the phase shift control signal holding circuit 43 and the level control signal holding circuit 44 respectively held in the previous recording mode are used. The phase control signal and the level control signal set the good comb filter characteristics shown in FIG. 11, so that the carrier color signal C1
The crosstalk component Cc is sufficiently suppressed from the start of supply of 1'. For this reason, a high-quality reproduced image with a good S/N ratio can be obtained from the start of image reproduction.

When normal recording mode is specified, switch 41
, 46 are closed to the N side.

The carrier color signal C1 inputted from the input terminal 67 is superimposed with a pilot signal as described above in the pilot signal superimposition circuit 40, and then passed through the switches 41, 46 . BPF47'kAD,
The main converter 48 converts the signal into a low frequency signal. The output signal of the main converter 48 is supplied to the LPF 49, unnecessary components are removed, and the output signal is sent to the output terminal 5 as a low frequency converted carrier signal 02P.
7 is output for recording.

On the other hand, the VCO 52 is controlled by an AFC processing circuit 53 to which its output signal and a horizontal synchronizing signal from the input terminal 39 are supplied. , in the case of the PAL system, a signal with a frequency of 375 fFi is output. VC
The output signal of O52 is supplied to a phase shifter 54 and input terminal 3
In synchronization with the horizontal synchronization signal from 9 and the vertical synchronization signal from input terminal 59, in the case of the NTSC system, 18
The phase is shifted by 0° and the phase direction is reversed every field, and in the case of PAL system, the phase shift direction is reversed by 90° every 1H.
The phase is shifted so that the direction of phase shift is reversed for each field. The output signal of the phase shifter 54 is sent to the sub-converter 5
5 is the output signal S of VC:051. The frequency of the signal is converted by , and the signal is supplied to the main converter 48 via the BPF 56 .

In this way, the low-pass converted carrier color signal 02P is recorded with the pilot signal superimposed thereon.

In the above explanation, 8 mm video was used as an example, but it goes without saying that the present invention can be applied to other VTRs.

Further, in FIG. 1, the output signal of O8C:26 may be directly supplied to the detector 15 and the phase detector 13, and the pilot gate 10 can be omitted. However, when the amplitudes of the carrier color signal cap and the delayed carrier color signal C1pn match, the output levels of the detectors 15, 35 . It is necessary to set the characteristics such as LPF16.35.

Furthermore, in FIG. 9, as the comb filter 7,
A conventional comb filter may be used, and it may also be used for the recording system.

By the way, in the PAL system, processing is performed in which the phase of the burst signal sequentially changes by ±135° every 1H. Therefore, there is a problem that it takes a long time for the APC circuit for removing jitter during reproduction to become stable. Therefore, for example, as shown in the CIP of FIG. 2 used in the present invention, a pilot signal whose phase is constant at 4.43 MHz is superimposed upon recording, and APC processing is performed in place of the burst signal. (PA
L-β method). Therefore, in the present invention, the pilot signal used for phase and level control of the delayed carrier color signal is
It is also possible to use it as a pilot signal for the PAL-β system.

〔Effect of the invention〕

As explained above, according to the present invention, the comb-shaped filter phase adjustment and level adjustment are automatically performed, so that the comb-shaped filter does not have to be adjusted due to adjustment variations or temperature characteristics in the adjustment process to ensure the comb-shaped filter performance. It is possible to completely prevent deterioration of image quality due to performance deterioration or lack of noise low frequency range, and furthermore, the process of adjusting the comb filter at the time of manufacturing is no longer necessary, resulting in an excellent effect of reducing product cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a carrier color signal processing circuit according to the present invention, FIG. 2 is a diagram showing the process of superimposing a pilot signal on the carrier color signal in FIG. 1, and FIGS. 3 and 4. 5 is a diagram illustrating the phase adjustment operation of the comb filter in FIG. 1, FIG. 5 is a characteristic diagram of the variable phase shift circuit in FIG. 1, and FIG. 6 is a diagram illustrating the level adjustment operation of the comb filter in FIG. 7 is a characteristic diagram of the comparator in FIG. 1, FIG. 8 is a characteristic diagram of the variable gain circuit in FIG. 1, and FIG. 9 is another implementation gA of the carrier color signal processing circuit according to the present invention.
FIG. 10 is a block diagram showing an example of a conventional carrier color signal processing circuit. FIG. 11 is a characteristic diagram of the best phase adjustment and level adjustment of a comb filter.
FIG. 2 is a characteristic diagram when the phase adjustment is insufficient, and FIG. 16 is a characteristic diagram when the level adjustment is inferior. 7... Comb filter, 8... Pilot signal superimposition circuit, 9... Subtractor, 10.11... Pilot gate, 12... 90° phase shifter, 13... Phase detector , 14...Low pass filter, 15...Detection i, 1
6...Lohas filter, 17...Comparator, 18.
...Variable gain circuit, 19...Variable phase shift circuit, 20...
- Delay element, 35... Detector, 56... Low pass filter, 40... Pilot signal superimposition circuit, 41.4
2... Switch, 43... Phase shift control signal holding circuit,
44... Level system @ signal holding circuit. Figure 2 Figure 3 Figure 5 Zeroing Figure 7 iA8 Figure 110 Figure 1z Figure 13

Claims (1)

[Claims] 1. A delay element to which a carrier color signal mixed with noise components due to frequency interleaving is input and delays the carrier color signal by one or two horizontal periods; and a delay element that delays the carrier color signal by one or two horizontal periods; In a carrier color signal processing circuit that includes a comb filter having a subtracter that performs subtraction processing with a delayed carrier color signal and removes the noise component, a pilot signal is used to superimpose a pilot signal on the input carrier color signal. a superimposition circuit; a first control signal generation circuit that generates a phase shift control signal according to a phase difference between a non-delayed pilot signal that is not delayed by the delay element and a delayed pilot signal extracted from the delayed carrier color signal; a second control signal generation circuit that generates a level control signal according to a level difference between the delayed pilot signal and the delayed carrier color signal; A variable phase shift circuit for adjusting and a variable gain circuit whose gain is controlled by the level control signal to adjust the level of the delayed carrier color signal are provided, and the noise component is sufficiently suppressed by the subtracter. A carrier color signal processing circuit characterized in that the phase and level of an input carrier color signal and the delayed carrier color signal can be automatically adjusted. 2. In claim 1, the pilot signal superimposition circuit is provided in a recording system, and the first,
A control signal holding circuit is provided in each of the second control signal generating circuits, and by supplying the carrier color signal outputted from the pilot signal superimposing circuit to the comb filter together with a reproduction mode command, A carrier color signal processing circuit characterized in that the phase shift amount of the variable phase shift circuit and the gain of the variable gain circuit can be set respectively.