JPH0783497B2 - Color signal modulation circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal modulation circuit,
The present invention relates to a color signal modulation circuit that modulates a color signal obtained by a video camera.

[0002]

2. Description of the Prior Art FIG. 7 shows a CCD (Char
Fig. 3 shows a block diagram of a signal processing system of a color video camera using a g Coupled Device). In the figure, light from a subject is incident on a CCD 2 by a lens system 1, and an electric signal photoelectrically converted therein is a CDS (Correlated Double Samplin).
g) Noise is suppressed in 3. The output signal of the CDS 3 has its amplitude controlled by the pre-processing circuit 4, and is then separated into a luminance signal and a chrominance signal by the Y / C separation circuit 5. Of these, the luminance signal is subjected to correction processing such as emphasis in the luminance processing circuit 6 and is output from the terminal 6a, while the color signal is subjected to signal processing such as matrix calculation and modulation in the color processing circuit 7 and is output. The signal is output from the terminal 7a.

FIG. 8 shows a block diagram of a video signal processing system of a video tape recorder. In the figure, the composite video signal coming from the terminal 8a is supplied to the low-pass filter 8 where the luminance signal component is extracted. This luminance signal is high-frequency emphasized in the pre-emphasis circuit 9 so as to be less susceptible to the influence of modulation noise, then FM-modulated by the FM modulator 10 and supplied to the mixer 14.

On the other hand, the composite video signal from the terminal 8a is supplied to the bandpass filter 11 where the modulated color signal component is extracted. The modulated chrominance signal component is frequency-converted into a low frequency band by the balanced modulator 12, and the modulated chrominance signal component in the lower detection band is extracted by the low pass filter 13 and supplied to the mixer 14. The mixed signal of the FM luminance signal and the low frequency modulation color signal output from the mixer 14 is amplified by the recording amplifier and then recorded on the magnetic tape by the magnetic head 16.

Next, the reproduction signal reproduced from the magnetic tape by the magnetic head 16 is amplified by the preamplifier 17,
It is supplied to the high-pass filter 18 and the low-pass filter 21.
The reproduced FM luminance signal extracted by the high-pass filter 18 is FM.
The demodulator 19 demodulates the luminance signal, and the de-emphasis circuit 20 restores the original signal before the high-frequency emphasis due to the characteristic opposite to that of the pre-emphasis circuit 9 at the time of recording, thereby reducing the modulation noise and supplying it to the mixer 24. To be done.

On the other hand, the reproduced low-pass modulated color signal extracted by the low-pass filter 21 is frequency-converted into the original frequency band by the balanced modulator 22, and then the crosstalk component from the adjacent track is removed by the comb filter 23. It is then supplied to the mixer 24. The mixer 24 adds and mixes the reproduced luminance signal and the modulated chrominance signal and outputs the result from the terminal 24a. Here, in the single-plate type color camera, it is necessary to arrange color filters in front of the monochrome image pickup device in order to obtain a color signal from one image pickup device CCD. Color information obtained from the light passing through this filter is output as a line-sequential signal as described below. Here, the color-difference line-sequential method, which is widely used at present, will be described.

Cy (cyan), Ye (yellow), Mg
FIG. 9 shows a complementary color filter in which four pixels of (magenta) and G (green) are arranged in 8 pixels as one unit.
The operation will be described below. The sum of charges accumulated in two pixels vertically adjacent (vertical) is read out. The deterioration of the vertical resolution is reduced by changing the combination of addition in each of the two fields that form one frame and reading them. In this way, the signal output from the CCD 2 is as shown in FIG.
As shown in (B). 10A shows an even field, and FIG. 10B shows an odd field. Here, when the complementary colors Ye, Mg, and Cy are represented by the primary colors R, G, and B, Ye =
R + G, Mg = R + B, Cy = B + G. CDS3
The output signal of is passed through a low-pass filter to obtain the sum of pixel information. A1 line in FIG. 1 1 (A) is (Cy + G) +
(Ye + Mg), A2 line is (Cy + Mg) + (Ye
+ G), and it can be seen that the A1 line and the A2 line are composed of the same component. When this is expressed in primary colors, both A1 line and A2 line become 2R + 3G + 2B,
It represents the luminance signal information. Next, when the output signal of the CDS 3 is passed through a bandpass filter, a change that occurs in the information between horizontally adjacent pixels is output. When the output signal of this bandpass filter is synchronously detected, the A1 line is (Cy + G)-
(Ye + Mg), A2 line is (Cy + Mg)-(Ye
+ G). If primary colors are expressed in the same way as the luminance signal, A1
The line is (2R-G) and the A2 line is (2B-G). 2R-G represents RY of the color difference signal, and 2B-G represents BY of the color difference signal. The color information obtained in this way is a line-sequential color difference signal.

As described above, the line-sequential color difference signals obtained by the Y / C separation circuit 5 are of two types (R-
(Y, B-Y) information is sequentially and repeatedly output. In order to modulate this signal and obtain a quadrature two-phase amplitude modulation color signal, two kinds of signals are required at the same time. The signal processing for obtaining these two types of signals simultaneously is sequential synchronization. 11 and 12 show a block diagram and a signal configuration diagram of a color signal modulation circuit of a conventional interpolation type sequential synchronization system, respectively. Figure 11
In, the color-difference line-sequential signal output from the Y / C separation circuit 5 enters the terminal 25a, and is delayed by the 1H (1 horizontal scanning period) delay circuit 25 by 1 horizontal scanning period. The selection circuits 26 and 27 select a signal delayed by one horizontal scanning period and a signal directly input. The selection circuits 26 and 27 are
Switching control is performed at a half cycle of the horizontal scanning cycle, and signals that are contradictory to each other are selected. 12A shows the input signal of the terminal 25a, FIG. 12B shows the output signal of the 1H delay circuit 25, and FIGS. 12C and 12D show the output signals of the selection circuits 26 and 27, respectively.

The modulation circuit 28 modulates the RY signal, and the modulation circuit 29 modulates the BY signal. These carrier waves have the same frequency and a phase difference of 90 degrees from each other, and by adding these modulated signals in the mixer 30, a quadrature two-phase amplitude modulated modulated color signal is obtained, and the band-pass filter 3
1, the unnecessary frequency components are removed and supplied to the balanced modulator 12. FIG. 12F shows the output signal of the bandpass filter 31.

By the way, in a video tape recorder, recording is performed on a magnetic tape by helical scanning of a pair of magnetic heads provided with azimuth without providing a guard band in order to lengthen the recording time. In addition, since the color signal is converted into the low frequency range and recorded, the azimuth effect is not so great during playback, so the PS (Phase Shift) method or PI (Phase Phase) method
The crosstalk component is removed by the comb filter 23 by the Inverter method. Comb filter 23
In the case of the NTSC system, 1H delay circuit 23a and mixer 2
3B, it outputs the signal shown in FIG. 12G when supplied with the signal shown in FIG. 12E.

13 and 14 show a block diagram and a signal configuration diagram of a conventional average type sequential synchronization system color signal modulation circuit, respectively. The color difference line sequential signal output from the Y / C separation circuit 5 is input from the terminal 25a, delayed by one horizontal scanning period by the 1H delay circuit 25, and further the 1H delay circuit 3
3 is delayed by one horizontal scanning period. in this way,
Here, there are three types of input (non-delayed) signal, 1 horizontal scanning period delay signal, and 2 horizontal scanning period delay signal. The mixer 34 adds and averages the input signal and the signal delayed by two horizontal scanning periods. Since this average color difference signal has a double amplitude component, the 1H delay circuit 2
A circuit 32 for doubling the amplitude is inserted on the output side of 5 to match the amplitude with the output signal of the mixer 34. The average color difference signal and the one horizontal scanning period delay signal are selected by the selection circuits 26 and 27. The selection circuits 26 and 27 select mutually contradictory signals in a cycle that is half of one horizontal scanning cycle. FIG. 14 (A)
(F) shows the input signal of the terminal 25a, the output signal of the 1H delay circuit 25, the output signal of the 1H delay circuit 33, the output signal of the mixer 34, the output signal of the selection circuit 26, and the output signal of the selection circuit 27, respectively. ing.

The color difference signals output from the selection circuits 26 and 27 are subjected to quadrature two-phase amplitude modulation by the modulation circuits 28 and 29 and the mixer 30, unnecessary frequency components are removed by the band-pass filter 31, and shown in FIG. Signal. When the comb filter 23 is supplied with the signal shown in FIG. 14 (G), the output signal of the 1H delay circuit 23a becomes as shown in FIG. 15 (H), and the mixer 23b outputs the signal shown in FIG. 14 (I). Is output.

[0013]

In the interpolation type sequential synchronization system of FIG. 11, since the image taken by the camera is displayed on the monitor, when the output of the bandpass filter 31 is selected by the selection circuit 34, the vertical resolution is output. Becomes rough. This is
This is because the same component is repeated for a period of 2H as can be seen from (E), and the horizontal striped pattern is a display screen that is disturbed in the vertical direction. However, when this signal is once recorded on a magnetic tape and reproduced, the comb-shaped filter 23 reduces the roughness in the vertical direction.

In the average type sequential synchronization system of FIG. 13, the roughness of the vertical resolution of the output signal of the band-pass filter 31 is apparently reduced as compared with the system of FIG. However, once recorded on a magnetic tape and reproduced, since the reproduced signal passes through the comb filter 23, there is a problem that color bleeding in the vertical direction is large as shown in FIG. The present invention has been made in view of the above points, and it is possible to reduce the roughness in the vertical direction of the screen monitoring the image from the camera during recording,
Another object of the present invention is to provide a color signal modulation circuit capable of reducing color blurring in the vertical direction of the screen during reproduction and reducing the number of circuits.

[0015]

A color signal modulation circuit of the present invention comprises a first modulator for modulating a line-sequential color difference signal and a modulation color signal output from the first modulator for one horizontal scanning period. A first delay circuit for delaying, a modulated color signal output from the first modulator, and a modulated color signal delayed by the first delay circuit are mixed to interpolate sequentially synchronized magnetic tape. A first mixer for generating a modulation color signal for recording, and a comb for generating an average type sequentially synchronized monitor color signal from the modulation color signal for recording output from the first mixer. Shape filter.

The modulated color signal reproduced from the magnetic tape is frequency-converted by the first modulator into the frequency band before recording, and the frequency-converted modulated color signal is converted into the first delay circuit and the first delay circuit. It feeds a comb filter consisting of a mixer to remove crosstalk from adjacent tracks. Further, the second delay circuit for delaying the line-sequential color difference signal for one horizontal scanning period and the line-sequential color difference signal and the color difference signal delayed by the second delay circuit are contradictory to each other and switched at 1/2 horizontal scanning period. First and second selection circuits for selection, and second and third modulators for modulating the color difference signals output by the first and second selection circuits with carrier waves having 90 ° different phases,
A second mixer that mixes the modulation color signals output from the second and third modulators to generate interpolation-type sequentially synchronized modulation color signals for magnetic tape recording; and the second mixer. And a comb-shaped filter for generating an average-type sequentially synchronized monitor modulation color signal from the recording modulation color signal output from the mixer.

Further, the modulated color signal reproduced from the magnetic tape is selected by the first selection circuit so as to be supplied to the second modulator, reproduced from the magnetic tape and delayed by the second delay circuit. After the modulated color signal is selected by the second selection circuit so as to be supplied to the third modulator, and the modulated color signals are frequency-converted into the frequency bands before recording by the second and third modulators respectively, Mix in a second mixer to remove crosstalk from adjacent tracks.

[0018]

In the present invention, since the modulation color signal for recording on the magnetic tape is used as the modulation color signal for monitoring by the comb filter, the roughness of the monitor screen in the vertical direction during recording can be reduced,
Since the interpolation type sequentially synchronized modulated color signals are recorded on the magnetic tape, vertical color bleeding at the time of reproduction can be reduced, and the modulation circuit, the delay circuit, and the mixer are shared during recording and reproduction. Can reduce the number of circuits.

[0019]

1 is a block diagram of a first embodiment of the circuit of the present invention. 7, those parts which are the same as those corresponding parts in FIGS. 7 and 8 are designated by the same reference numerals, and a description thereof will be omitted. In FIG. 1, the terminal 41
Line-sequential color difference signals are supplied to the selection circuit 4 during recording.
2 selects the signal from the terminal 41 and supplies it to the modulator 43. The modulator 43 performs balanced modulation of the carrier wave with the color difference signal having the structure shown in FIG. The carrier wave is generated by the APC (automatic phase control) circuit of the recording color signal processing circuit, and the phase is delayed by 90 degrees when the BY signal is modulated with respect to when the RY signal is modulated. Here modulated color signal obtained is as shown in FIG. 2 by 1H delay circuit 46 is supplied to the mixer 45 a (B) 1
After being delayed by the horizontal scanning period, the signals are supplied to the mixer 45 a and are added and mixed to obtain a quadrature two-phase amplitude-modulated modulated color signal having the configuration shown in FIG. This modulated signal is shown in FIG.
(E) has the same configuration as the modulated color signal obtained by the interpolating type sequential synchronization, is balanced-modulated by the modulator 12 and frequency-converted to a low frequency band, and is modulated by the low-pass filter 13 in the lower detection band. The color signal component is taken out, amplified by the recording amplifier, and then recorded on the magnetic tape by the magnetic head 16.

Furthermore, the output signal of the mixer 45 a mixing vessel 4
Figure 2 1H delay circuit 47 is supplied to 5b (D)
As shown in (1), the signals are delayed by one horizontal scanning period, supplied to the mixer 45b , added and mixed, and a modulated color signal having the configuration shown in FIG. 2 (E) is obtained. This modulated color signal has the same structure as the average type sequentially synchronized modulated color signal shown in FIG. 14G, and this signal is selected by the selection circuit 48 in order to display the image taken by the camera during normal recording on the monitor. And is output from the terminal 49. When the output signal of the camera is recorded on the external video tape recorder, the mixer 4 is selected by the selection circuit 48.
5a , which outputs the interpolation type sequentially synchronized modulated color signal of 5a is selected and output.

Next, during reproduction, the reproduction signal of the magnetic head 16 is amplified by the preamplifier 17, then selected by the selection circuit 42 and supplied to the modulator 43. Modulator 43 during playback
Converts the reproduction modulated color signal into the original frequency band by using the carrier wave coming from the terminal 44b. The carrier wave is a signal generated by the APC circuit of the reproduction color signal processing circuit. The modulated color signal converted to the original frequency band is mixed by the mixer 4
The comb filter composed of the 5 and 1H delay circuits 46 has the structure shown in FIG. 2G, and the crosstalk is removed, and the signal is selected by the selection circuit 48 and output from the terminal 49.

FIG. 3 shows a block diagram of a video tape recorder integrated with a camera using the circuit of the present invention. In the figure, those parts which are the same as those corresponding parts in FIGS. 1, 7 and 8 are designated by the same reference numerals, and a description thereof will be omitted. Further, the signal path at the time of recording of the circuit of FIG. 3 is shown in FIG. 4 by removing unnecessary portions, and the signal path at the time of reproduction is shown in FIG. 5 by removing unnecessary portions. In FIG. 3, the timing signal generation circuit 51 is a CCD that outputs a discrete signal.
2 generates timing signals for timing such as vertical and horizontal synchronization with other circuits. The timing signals are CCD2, CDS3, pre-process circuit 4, Y /
It is supplied to the C separation circuit 5 and the selection circuit 52, respectively.

Oscillation of VXO (voltage controlled crystal oscillator) 54
The frequency is the color subcarrier frequency f_sc(3.58 for NTSC system
Horizontal scanning frequency f in MHz_H227.5 times)
4f _scThis oscillation frequency signal is horizontally driven by the frequency divider 55.
The frequency is divided into an integral multiple of the check cycle and supplied to the phase comparator 56.
It At the time of recording, as shown in FIG.
The luminance signal passes through the selection circuit 57 and the sync signal separation circuit 58
The horizontal sync signal separated here is
The phase comparator 56 is supplied to the phase comparator 56.
The output signal of is compared with the horizontal period signal to generate the phase error signal.
To achieve. This error signal is passed through the selection circuit 59 to the low frequency filter.
The phase error signal supplied to the filter 61 and integrated here.
By supplying the VXO54 to the AFC circuit,
There is.

On the other hand, the oscillation frequency signal output from the VXO 54
Is 1/4 divided by the phase shift circuit 62 and f _scAfter being said,
The reference signal that is the carrier wave and the phase delayed by 90 degrees
The selected signal is extracted and supplied to the selection circuit 52.
The selection circuit 52 is controlled by the timing signal to output the color difference signal.
Selects the reference color subcarrier during RY signal modulation and
A color subcarrier delayed by 90 degrees is selected when the signal is modulated. Election
The color subcarrier selected by the selection circuit 52 is selected by the selection circuit 6 during recording.
3 is supplied to the modulation circuit 43, and the modulation circuit 43 is selected.
At, the color subcarrier is modulated by the color difference signal. Get here
The modulated color signal generated is an unnecessary frequency component by the bandpass filter 64.
Is supplied to the mixer 45 and the 1H delay circuit 46.
Be done.

When recording in the NTSC-VHS format, the VCO (voltage controlled oscillation) circuit 65 has a frequency of 1
It oscillates at 070f _H , divides the oscillation frequency signal by 1/4 by the phase shift and phase shift circuit 66, shifts by 90 degrees, and changes the frequency.
The four kinds of signals of 267.5 (227.5 +40) f _H are supplied to the selection circuit 67, and the signals sequentially selected here are supplied to the balanced modulator 12 as carrier waves. Also, after the oscillation frequency signal of the VCO 65 is divided by the frequency divider 68 by 1/1070, the selection circuit 69
Is selected by and supplied to the phase comparator 71.
The horizontal synchronizing signal obtained in step 1 is selected by the selection circuit 72 and supplied to the phase comparator 71 to generate a phase error signal from the signal from the frequency divider 68. This phase error signal is passed through the low pass filter 73.
Is smoothed by and is supplied to the VCO 65 to form an AFC loop.

At the time of reproduction, the reproduction low-pass conversion color signal output from the low-pass filter 21 is selected by the selection circuit 42, and the modulator 6 is selected.
3 is supplied. Further, the output voltage of the DC power supply 80 selected by the selection circuit 59 is supplied to the VXO 54, and the VXO 54 is supplied.
54 is a free run state. The oscillating frequency signal is _divided into 1/4 by the phase shift circuit 62, and the color subcarrier having the frequency f _sc is selected by the selection circuit 72 and supplied to the phase comparator 71. The reproduction modulation color signal selected by the selection circuit 69 is supplied to the phase comparator 71, and the phase error signal output from the phase comparator 71 is output to the VCO through the low pass filter 73.
Then, the oscillation frequency of the VCO 65 is controlled and the jitter is corrected.

Further, the reproduction luminance signal output from the de-emphasis circuit 20 is filtered by the low-pass filter 81 to remove unnecessary high-frequency components, and then supplied to the sync separation circuit 58 from the selection circuit 57 to separate the horizontal sync signal. The side lock detection circuit 82 counts the number of cycles of the VCO 65 in the horizontal synchronization period, and when the counted number exceeds a predetermined range, outputs a correction pulse and adjusts the level of the phase error signal supplied to the VCO 65 to set the VCO 65 to a predetermined value. To oscillate at the frequency.

As described above, since the modulation color signal for recording on the magnetic tape is used as the modulation color signal for monitoring by the comb filters 46 and 47, the roughness of the monitor screen in the vertical direction at the time of recording can be reduced and the interpolation type Since the sequentially synchronized modulated color signals of are recorded on the magnetic tape, vertical color bleeding at the time of reproduction can be reduced. By using the modulation circuit, the delay circuit and the mixer for both recording and reproduction, The number can be reduced.

FIG. 6 shows a block diagram of a second embodiment of the circuit of the present invention. In the figure, those parts which are the same as those corresponding parts in FIGS. 1 and 11 are designated by the same reference numerals, and a description thereof will be omitted. In FIG. 6 , the line-sequential color difference signal coming into the terminal 41 has the same structure as that of FIG.
The modulated color signals are supplied to the H delay circuit 25 and the selection circuits 26 and 27, and quadrature two-phase amplitude modulation is generated by the modulators 28 and 29 and the mixer 30, and the interpolation type sequential synchronization is performed. At this time, the modulators 28 and 29 are connected to the terminals 28a and 29, respectively.
Carrier waves that come from a and are 90 degrees out of phase with each other are used.

The modulated signal is balanced-modulated by the modulator 12 and frequency-converted to a low frequency band, the modulated color signal component of the lower detection band is taken out by the low-pass filter 13, amplified by the recording amplifier, and then the magnetic signal. It is recorded on the magnetic tape by the head 16. Furthermore, the output signal of the mixer 30 is a mixer 4 5b is supplied to one horizontal scanning period delay has been mixer 4 5b by 1H delay circuit 47 is supplied is added mixed, modulated color signal is obtained. This modulated color signal has the same structure as the average type sequentially synchronized modulated color signal shown in FIG. 14G, and this signal is selected by the selection circuit 48 in order to display the image taken by the camera during normal recording on the monitor. And is output from the terminal 49. When the output signal of the camera is recorded on an external video tape recorder, the mixer 3 is used by the selection circuit 48.
An interpolating-type sequentially synchronized modulated color signal output by 0 is selected and output.

Next, at the time of reproduction, the reproduction signal of the magnetic head 16 is amplified by the preamplifier 17 and then selected by the selection circuit 42. The selection circuit 26 outputs the output of the selection circuit 42 to the modulator 2
8, and the selection circuit 27 supplies the output of the 1H delay circuit 25 to the modulator 29. Each of the modulators 28 and 29 has a terminal 28.
The reproduced modulated color signal is frequency-converted into the original frequency band by the balanced modulation using the carrier waves supplied from each of b and 29b. The modulated color signal converted into the original frequency band is mixed by the mixer 3
At 0, the signals are added and mixed to remove crosstalk, selected by the selection circuit 48, and output from the terminal 49.

In this embodiment, the color signal before modulation is delayed by the 1H delay circuit 25 at the time of recording, and the reproduced modulated color signal which has been low-pass converted at the time of reproduction is delayed by the 1H delay circuit 25.
When the 1H delay circuit 25 is composed of a CCD, the number of CCD stages can be smaller than that of a circuit that delays the modulated color signal.

[0033]

As described above, according to the color signal modulation circuit of the present invention, it is possible to reduce the roughness in the vertical direction of the screen on which the image from the camera is monitored during recording, and the color in the vertical direction of the screen during reproduction. Bleeding can be reduced and the number of circuits can be reduced, which is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a circuit according to the present invention.

FIG. 2 is a signal configuration diagram of each part of the circuit of FIG.

FIG. 3 is a block diagram of a camera-integrated video tape recorder using the circuit of FIG.

FIG. 4 is a diagram for explaining the recording operation of FIG.

FIG. 5 is a diagram for explaining the reproduction of FIG. 3;

FIG. 6 is a block diagram of a second embodiment of the circuit of the present invention.

FIG. 7 is a block diagram of a color video camera.

FIG. 8 is a block diagram of a video signal processing system of a video tape recorder.

FIG. 9 is a diagram showing a configuration of a complementary color filter.

FIG. 10 is a diagram showing a configuration of a CCD output signal.

FIG. 11 is a block diagram of a conventional circuit.

12 is a signal configuration diagram of each part of the circuit of FIG.

FIG. 13 is a block diagram of a conventional circuit.

14 is a signal configuration diagram of each part of the circuit of FIG.

[Explanation of symbols]

 25,46,47 1H delay circuit 26,27,42,48 selection circuit 28,29,43 modulator

Claims (4)

[Claims] 1. A first modulator for modulating a line-sequential color difference signal, a first delay circuit for delaying a modulated color signal output from the first modulator by one horizontal scanning period, and the first delay circuit. The modulated color signal output from the modulator and the first
A first mixer that mixes with the modulated color signal delayed by the delay circuit to generate an interpolated sequentially synchronized modulated color signal for magnetic tape recording, and a recording output from the first mixer. And a comb-shaped filter for generating an average-type sequentially synchronized monitor color signal from the monitor color signal. 2. The color signal modulation circuit according to claim 1, wherein the modulation color signal reproduced from the magnetic tape is frequency-converted by the first modulator into a frequency band before recording, and the frequency conversion is performed. Is supplied to a comb filter composed of the first delay circuit and the first mixer to eliminate crosstalk from adjacent tracks. 3. A second delay circuit for delaying the line-sequential color difference signal for one horizontal scanning period, and the line-sequential color difference signal and the color difference signal delayed by the second delay circuit are contradictory to each other, and 1/2 horizontal scanning is performed. First and second selection circuits that switch and select at a cycle, and second and third modulators that modulate the color difference signals output by the first and second selection circuits by carrier waves having 90 ° different phases. A second mixer that mixes the modulation color signals output from the second and third modulators to generate an interpolation-type sequentially synchronized modulation color signal for magnetic tape recording, and the second mixer And a comb-shaped filter for generating an average-type sequentially synchronized modulation color signal for monitoring from the modulation color signal for recording output from the mixer. 4. The color signal modulation circuit according to claim 3, wherein the modulated color signal reproduced from the magnetic tape is selected by the first selection circuit so as to be supplied to the second modulator, and is reproduced from the magnetic tape. The modulated color signal delayed by the second delay circuit is supplied to the third modulator.
The second and third modulators convert the modulated color signals to the frequency band before recording, and then the second mixer mixes them to eliminate crosstalk from adjacent tracks. A color signal modulation circuit characterized by removal.