JPS6013599B2 - SECAM color video signal reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a VTR (magnetic recording and reproducing apparatus) that can appropriately reproduce SECAM color video signals even if they are recorded at high density.

When recording a luminance signal (black and white video signal) on a magnetic tape, etc., by converting the luminance signal into an FM signal and performing so-called azimuth recording, it is possible to eliminate crosstalk between tracks due to azimuth loss during playback. F
M brightness signals can be reproduced, therefore high-density recording can be performed without guard bands between adjacent magnetic tracks, and long-time recording and reproduction can be performed with a small amount of tape used.

Therefore, when recording SECAM color video signals,
It is conceivable to frequency-convert the carrier color signal to reduce the FM luminance signal, add it to the FM luminance signal, and perform azimuth recording at the same time.

However, if the data is simply recorded in this way, there will be no problem with the luminance signal during playback, but since the carrier color signal has a low frequency band, it cannot be expected to reduce inter-track crosstalk due to azimuth loss. Inter-track crosstalk occurs in the carried color signal, which appears as noise on the playback screen.

In view of these points, the present invention prevents noise caused by inter-track crosstalk during playback even when SECAM color video signals are recorded at high density, and in particular, provides a clear color playback image. The aim is to provide a VTR.

Therefore, in the present invention, for example, the carrier color signal is low-frequency converted, and the phase (initial phase) of the carrier color signal is made constant in every horizontal period in every other track, and the remaining every other track is In the track, reproduction is performed from the tape recorded with the phase of the carrier color signal inverted every two horizontal periods.

During reproduction, the phase of the carrier color signal is made constant no matter which track it is reproduced from, and crosstalk between tracks is attenuated by a filter having a soft type Y-comb characteristic. An example of this invention will be explained below.

Note that the carrier color signal of the SECAM color video signal is a line sequential signal consisting of an FM signal based on a red color difference signal and an FM signal based on a blue color difference signal, and although the carrier frequencies of both FM signals are different from each other, the following explanation will be given. Now, for simplicity, carrier frequency fs=277fh (fh is horizontal frequency, fs34
．． 33MHz). In Figure 1, 11~
34 is a recording system, 41 to 56 is a reproduction system, 80 is a head drum servo circuit, and 91 to 94 are recording and reproduction changeover switches. These switches 91 to 94 are switched to contact R during recording, and are switched to contact R during reproduction. Switched to contact P. The remaining circuits are used for both recording and reproduction. During recording, the SECAM color video signal is supplied to the low-pass filter 12 through the input terminal 11 and a luminance signal is taken out.
3→Clamp circuit 1 4→Pre-amplification circuit 15→
The signal is supplied to the FM modulation circuit 17 through the line of the dark and white clipping circuit 16 to form an FM signal, and this signal is supplied to the addition circuit 19 through the high-pass filter 18.

Further, the signal from the terminal 11 is transmitted to the bandpass filter 31.
The carrier color signal Ss (carrier frequency fS) is taken out, and this signal Ss is supplied to the reverse filter 32 and the AC
The signal is supplied to the frequency converter 34 through the C circuit 33.

In this case, as shown in FIG. 2, if every other field period is a period Ta and the remaining field period is a period Th, then in the SECAM color video signal, the subcarrier of the carrier color signal Ss The phase is locked to that shown in FIG. 2A. In other words, the phase of the subcarrier of the carrier color signal Ss is locked to 0 (reference phase) during the 3 m horizontal period of the field period Ta and the horizontal period of the (3h11) mark, with 3 horizontal periods as one set, and ( In the 3h + 2)th horizontal period, it is locked to w (reverse phase), and in the field period Tb, the trajectory is locked, and in the (trajectory + 1)th horizontal period, m is locked.
and is locked to 0 in the (trajectory+2)th horizontal period (however, the values of m and n are integers and differ by 2 for each field period). Note that this phase lock is called dot interleaving. This signal Ss is then low-frequency converted by an alternating signal Sq having a phase as shown in FIG. 2D. That is, 60 indicates an AFC circuit, in which an oscillation signal whose free-running frequency is an integral multiple of the horizontal frequency fh, for example, frequency 44fh, is taken out from VC0 (voltage controlled variable frequency oscillation circuit) 63, and this signal is sent to a frequency dividing circuit 64. This frequency-divided signal is supplied to the phase comparison circuit 62, and the luminance signal from the amplifier 13 is sent to the synchronous separation circuit 61 through the contact R of the switch 92. The horizontal synchronizing pulse Ph is taken out, this pulse Ph is supplied to the comparator circuit 62, and the comparison output is supplied to the VC063 as its control signal. Therefore, the VC063 oscillation signal has a frequency of 44f
h and is synchronized with the horizontal synchronization pulse Ph. and,
This oscillation signal is supplied to the frequency converter 71, and an oscillation signal with a frequency fs is supplied from the oscillation circuit 72 to the converter 71.The oscillation signal is then supplied from the converter 71 to the frequency fq (= fc + fs), which is the sum of both signals. As shown in FIG. 2B, an alternating signal Sq whose phase is 0 is extracted in each horizontal period.

Further, the signal Sq is supplied to one input contact of the switch circuit 73, and is inverted in phase by an inverter 74 to keep the phase constant, and then supplied to the other input contact of the switch circuit 73, and The control signal Sr is supplied from the control circuit 100 to the switch circuit 73.

The details of this control circuit 100 will be described later, but the control circuit 100' includes a horizontal synchronizing pulse P from the separation circuit 61.
h is supplied, and pulses synchronized with the rotation of the rotary head are also supplied.

Furthermore, the luminance signal from the amplifier 13 is combined with the sync separation circuit 81 through the switch 92 to generate the vertical sync pulse P.
v is taken out, and this pulse Pv is supplied to the control circuit 100, and at the same time, the carrier color signal Ss from the ACC circuit 33
is supplied to the gate circuit 131, and the discrimination signal (unmodulated subcarrier) Sj inserted into the back porch of the horizontal synchronizing pulse Ph is taken out, and this signal Si is sent to the control circuit 100.
supplied to In this way, the control circuit 10 is synchronized with the horizontal synchronizing pulse Ph, and as shown in FIG. A control signal Sr that is inverted every horizontal period and every four horizontal periods is formed. Then, this signal Sr is supplied to the switch circuit 73, and Sr=
When the signal is "1", the switch circuit 73 is switched to the inverter 74 side, contrary to the diagram. Therefore, the switch circuit 73
An alternating signal Sq is extracted from the signal Sq, and its phase changes as shown in FIG. 2D.

This signal Sq is then supplied to the converter 34.

Therefore, in the converter 34, the carrier color signal Ss is
The carrier frequency is frequency-converted to a carrier color signal Sc having a frequency fcfc=fq-fs.

In this case, the frequency fc of the signal Sc is obtained by subtracting the frequency fs of the signal Ss from the frequency fq of the signal Sq, so the phase of the signal Sc is also calculated by subtracting the frequency fs of the signal Ss from the phase of the signal Sq.
It is obtained by subtracting the phase of s, and therefore, the carrier color signal S
The phase of c is as shown in FIG.
ra is constant at 0, and the field period Tb' is
It is reversed every two horizontal periods. Then, this signal Sc is supplied to the adder circuit 19 and added to the low frequency band of the FM luminance signal from the filter 18. Polishing grooves are provided in the rotating magnetic heads IA and IB.
These heads IA and IB have an angular spacing of i80o from each other and are rotated by a motor 4 at a frame frequency, and a magnetic tape 2 is obliquely wound around the rotating cylindrical surface over an angular range of just over 180o. The tape 2 is run at a constant speed by a capstan and a pinch roller. Furthermore, the angles of the operating gaps, ie, the azimuth angles, of the heads IA and 1B' are different from each other. Further, the rotation of the heads IA and IB is synchronized with the luminance signal by eight servo circuits. That is, the vertical synchronization pulse Pv from the synchronization separation circuit 81 is supplied to the frequency division circuit 82 and divided into pulses of the frame frequency, and this pulse is coupled to the phase comparison circuit 83 through the contact R of the switch 93. Further, a pulse generating means 84 is provided in, for example, the rotary koji 5 of the heads IA and IB, from which one pulse is taken out for each rotation of the heads IA and IB, and this pulse is fed to a comparison circuit 83 through a shaping amplifier 85. be done. The comparison output of the comparison circuit 83 is then supplied to the motor 4 through the amplifier 86, and the head I
The rotational phases of A and IB are synchronized with the frame of the luminance signal.

Therefore, as shown in FIG. 3, the addition signal St of the field period Ta is recorded on the tape 2 as track 3A by the head IA, and the addition signal St of the field period Th
is recorded on tape 2 as track 3B by head IB.

In this case, by selecting the rotation radius of the heads IA, IB and the running speed of the tape 2, the tracks 3 are arranged to be adjacent to each other, and the position of the horizontal synchronizing pulse Ph in the tracks 3 is The tracks 3A, 38 are lined up on a line perpendicular to the track 3, so-called day alignment (horizontal synchronized alignment), and the tracks 3A, 38 are aligned in the length direction, for example, 2. It is shifted by a length of 1.5 mm (IH is the length of track 3 corresponding to one horizontal period).

Therefore, in track 3, the horizontal section of the red color difference signal (
0 mark) and the horizontal section (x mark) of the blue color difference signal are arranged on a line perpendicular to the track 3.

Further, the phase difference of the signal Sc at a certain point of the track 3A or 3B and a point two horizontal intervals away from the track 3A or 3B differs by m from the phase difference of the signal Sc at two corresponding points in the width direction of the track 38 or 3A. When the phase of the signal Sc is controlled in this way, the signal Sc of the track 3A and the signal Sc of the track 38 are interleaved with each other (the reason will be omitted).

Further, the frequency divided pulse from the frequency dividing circuit 82 is transmitted to the recording amplifier 87.
It is further supplied to the magnetic head 88 through the contact R of the switch 94, and is recorded on the side trailing portion of the tape 2 as a control pulse during reproduction.

As described above, the SECAM color video signal is transferred to tape 2.
recorded in

On the other hand, during reproduction, a control pulse is reproduced from the tape 2 by the head 88, and this pulse is transmitted from the contact P of the switch 94 to the reproduction amplifier 89 to the contact P of the switch 93.
The signal is supplied to the comparison circuit 83 through.

Therefore, the tracking servo of heads IA and IB for track 3 is performed, heads IA and IB scan track 3 in the same relationship as during recording, and add signal S from track 3.
t is played. In this case, tracks 3 are adjacent to each other, but head IA and track 3B have different azimuth angles, head IB and track 3A also have different azimuth angles, and the FM signal is recorded in the Takagi band. Therefore, the FM signal in the reproduced addition signal St has discs between tracks due to azimuth loss. No stalk has occurred. However, since the carrier color signal Sc is recorded in a low band, it cannot be expected that inter-track crosstalk due to azimuth loss will be reduced, and inter-track crosstalk will occur.

Therefore, as shown in FIG. 2F, during the field period Ta, the head IA scans the track 3A to reproduce the original carrier color signal Sc, and at the same time, the carrier color signal Sc of the adjacent track 3B is crossed. Also, during the field period Tb, the head IB scans the track 3B to obtain the original conveyed color signal S.
c is reproduced, and the carrier color signal Sc of the adjacent track 3A is obtained as the crosstalk signal Sk. In this way, the addition signal St including the crosstalk signal Sk
is obtained from the heads IA and IB, and this signal St is transmitted through the contact P of the switch 91 to the playback amplifier 41.
This signal is supplied to the high-pass filter 42 through the limiter 43 to extract the FM signal, this signal is supplied to the FM demodulation circuit 44 through the limiter 43 to demodulate the luminance signal, and this signal is supplied to the addition circuit 46 through the differential amplifier circuit 45. . Further, the addition signal St from the amplifier 41 is
The carrier color signal Sc [including the crosstalk signal Sk] is extracted by being supplied to the low-pass filter 51, and this signal S
c is supplied to the frequency converter 53 through the ACC circuit 52.

Furthermore, the luminance signal from the differential assist circuit 45 is
Synchronous separation circuits 61 and 81 through contact P of switch 92
Therefore, the converter 7
1, an alternating signal Sq with a constant phase is taken out, and
In the control circuit 1001, as shown in FIG. 2G, there is no inversion during the field period Ta, and the field period Tb
A control signal Sp that is inverted every two horizontal periods is formed, and this signal Sp is supplied to the switch circuit 73.

Therefore, an alternating signal Sq whose phase changes as shown in FIG. 2 is taken out from the switch circuit 73, and this signal Sq is supplied to the converter 53. Therefore, in the converter 53, the carrier color signal Sc [and crosstalk signal Sk] has a carrier frequency equal to the original frequency fsfs=fq
-fc is frequency-converted to a carrier color information signal Ss [and crosstalk signal Sk].

In this case, the frequency fs of the signals Ss, Sk is obtained by subtracting the frequency fc of the signals Sc, Sk from the frequency fq of the signal Sq. It is obtained by subtracting the phase of .
Therefore, as shown in FIG. 2, the phase of the carrier color signal Ss is constant, and the phase of the crosstalk signal Sk is inverted every two horizontal periods. Then, this carrier color signal Ss [and crosstalk signal Sk] is supplied to a soft type Y-shaped comb filter 54.

For example, as shown in FIG. 4, this filter 54 includes a delay circuit 54D that delays the input signal by two horizontal periods, an attenuator 54A that attenuates the delayed signal, and adds the attenuated signal and the original input signal. It is constituted by an adder circuit 54W. Therefore, in the adder circuit 54W, the carrier color signal Ss (and crosstalk signal Sk) of an arbitrary i-th horizontal period and the carrier color signal Ss [and crosstalk signal Sk] of the (i+2)-th horizontal period are added. In this case, the carrier color signal Ss has a constant phase as shown in FIG.
The signal Ss of the th horizontal period and the signal Ss of the (i12)th horizontal period are modulated by the same color difference signal and have a correlation. In addition, the crosstalk signal Sk is
As shown in FIG. 2, the phase is inverted every two horizontal periods. Therefore, in the adder circuit 54W, the carrier color signal Ss strengthens each other, and the crosstalk signal Sk weakens each other, so that the adder circuit 54W obtains the carrier color signal Ss and the crosstalk signal Sk at an attenuated level.

That is, if there is no attenuator 54A, the filter 5
The frequency characteristic of No. 4 is the characteristic shown by the broken line in Fig. 5.
In this invention, since the attenuator 54A is provided, the frequency characteristic of the filter 54 becomes a soft characteristic in which the level difference between the peak and the valley point is about 6 to IMB, as shown by the solid line in FIG. (The attenuation amount of the attenuator 54A is set in this way.)

Then, for such frequency characteristics, the carrier color information signal Ss
is distributed around positions that are integral multiples of horizontal frequency fh, and crosstalk signal Sk is distributed around positions that are odd multiples of horizontal frequency fh. '
This is distributed. Therefore, the carrier color signal Ss is
4, but the crosstalk signal Sk
will be attenuated. Then, the carrier color signal Ss [and the attenuated crosstalk signal Sk] from the filter 54 is supplied to the limiter 55, and the signal Ss is transmitted to the filter 54.
The partially attenuated sideband components are compensated by
This compensated signal Ss [and signal Sk] is supplied to the adder circuit 46 through the bell filter 56 and added to the luminance signal. A benign crosstalk-free SECAM color video signal is extracted.

In this case, the carrier color signal Ss of the reproduced SECAM color video signal includes the crosstalk signal Sk;
Since this is attenuated by the filter 54, it is not noticeable on the playback screen, and the phase of the crosstalk signal Sk is inverted every two horizontal periods as shown in FIG. Even if it appears as noise on the playback screen, this noise is canceled out by visual integration. Therefore, the crosstalk signal Sk in the reproduced SECAM color video signal does not pose any practical problem. That is, by manipulating the level and phase of the reproduced crosstalk signal Sk, the influence of this crosstalk signal Sk is eliminated.

Therefore, according to the present invention, as shown in FIG. 3, even if SECAM color video signals are recorded with high density so that there is no guard band between adjacent tracks 3A and 3B, the influence of inter-track crosstalk It can be played back without any damage, and therefore can be played back for a long time with a small amount of tape used.

Further, according to the present invention, since the attenuator 54A attenuates the delayed signal from the delay circuit 54D, color resolution is improved. That is, when the delayed signal from the delay circuit 54D is supplied to the adder circuit 54W without attenuation, the carrier color signal Ss from the adder circuit 54W includes a carrier color signal Ss that is not delayed, and a carrier color signal Ss that is delayed. Since each color contains 50% of the color signal Ss, the color resolution of the reproduced image is significantly reduced. However, according to the present invention, since the delayed signal of the delay circuit 54D is attenuated, the proportion of the delayed carrier color signal Ss included in the carrier color signal Ss from the adder circuit 54W is sufficiently less than 50%. Therefore, the color resolution of the reproduced image is improved. Further, the delay signal of the delay circuit 54D is transmitted to the attenuator 54.
Since it is attenuated by A, even if the characteristics of the delay circuit 54D are insufficient, it is not easily affected by it.

Furthermore, since the carrier chrominance signal Ss is an FM signal, loss of sideband components causes the same phenomenon as so-called overmodulation.
This appears as noise on the playback screen, but since the characteristics of the filter 54 are gentle as shown by the solid line in FIG. 5, there is almost no attenuation of sideband components, and no noise is generated on the playback screen.

Even if attenuation of sideband components occurs, it is compensated for by the limiter 55, so that a clear color image can be obtained without noise. Next, an example of the control circuit 100 will be explained with reference to FIG.

In FIG. 6, 11 is a signal forming circuit that forms a control signal Sp during reproduction, 120 is a signal forming circuit that forms a control signal Sr during recording, 130 is a phase regulating circuit that regulates the phase of the signal Sr, 95 is a recording/reproduction changeover switch.

In the forming circuit 11, a signal Sp is formed by a flip-flop circuit (hereinafter abbreviated as FF circuit).

That is, another pulse generating means 111 is provided on the rotating shaft 5, from which one pulse is taken out per one rotation of the heads IA, IB and which is shifted by one field period with respect to the pulse from the means 84. Pulse shaping amplifier 11
2 to the set terminal S of the FF circuit 113, and the pulse from the amplifier 85 is supplied to the FF circuit 11.
The outputs Q, 3 are supplied to the reset terminal R of No. 3, and are taken out from the FF circuit 113 in synchronization with the rotation of the heads IA, IB, as shown in FIG. 7B, which is inverted every field period. Then, this output Q,3 is outputted to the D-FF circuit 114.
At the same time, the vertical synchronizing pulse Pv shown in FIG.
No Ku. The FF circuit 114 outputs “0” to the field period Ta as shown in FIG. 7C.
Therefore, the output Q becomes "1" during the field period Tb,
4 is taken out. Then, this output Q,4 is JK-
At the same time, the horizontal synchronization pulse Ph shown in FIG. 7D is supplied from the synchronization separation circuit 61 to the clock terminal CP of the FF circuit 115.
A signal at the "1" level is supplied to the K input terminal of the FF circuit 115.

Therefore, as shown in FIG. 7E, the FF circuit 115 becomes "0" in the field period Ta, and in the field period Th, it is inverted every horizontal period, and the phase of this inversion is determined by which field. The same outputs Q and 5 are taken out from the periodic ear rb as well. Then, this output Q,5 is supplied to the clock terminal CP of the next JK-FF circuit 116, and the output Q,4 of the FF circuit 114 is supplied to the J input terminal of the FF circuit 116. A signal at a level of 1 is supplied to the K input terminal of the FF circuit 116.

Therefore, from the FF circuit 116, as shown in FIG. A signal that is the same during the field period Tb, that is, a control signal Sp during reproduction is extracted. During reproduction, this signal Sp is supplied to the switch circuit 73 through the reproduction side contact P of the switch 95.

Further, in the forming circuit 120, a signal S is formed by the output of the frequency dividing circuit 120A that performs frequency division by 1/3 and the signal Sp. That is, the horizontal synchronization pulse Ph from the synchronization separation circuit 61 is supplied to the T input terminal of the T-FF circuit 121, and its output Q2. is the next T-FF circuit 122
is supplied to the T input terminal of the FF circuit 121,1.
22 are supplied to an AND circuit 123, and the AND output Q23 is supplied to the clear terminals CL of the FF circuits 121 and 122 through an OR circuit 138. Therefore, as shown in FIG. 8B and C, the FF circuit 12
When the outputs Q2, , Q22 of 1, 1 and 22 are in the "0" state, as shown in FIG. 8A, when the first pulse Ph is supplied, the Q illusion becomes "1", and further , when the second pulse Ph is combined, Q2,="0" and Q22="1". When the third pulse Ph is supplied, Q2 becomes "1", and as a result, the output Q23 of the AND circuit 123 becomes "1" as shown in FIG. Output Q23
As a result, the FF circuits 121, 122 are cleared and immediately Q2, , Q2 becomes "0". Therefore, the state has returned to the state immediately before the first pulse Ph was supplied, so
Thereafter, if the pulse Ph is supplied, the same operation is repeated.

Then, after the third pulse Ph is supplied, Q2,,Q
The time it takes for Q22 to become "0" is determined by the response speed of the circuit and is almost 0, so as shown in FIG. 8C, the output Q22 becomes "1" for one horizontal period every three horizontal periods
". Then, this world power Q22 is supplied to the exclusive OR circuit 124, and the control signal Sp from the FF circuit 116 is supplied to the exclusive OR circuit 124 (see FIGS. 9A to 9D). Signals Ss, Ph, Sp,
(Reposting Q22).

Therefore, from the exclusive OR circuit 124, the ninth
As shown in FIG. A control signal S during recording is extracted.
During recording, this signal Sr is supplied to the switch circuit 73 through the recording side contact R of the switch 95.

As described above, the control signals Sr and S during recording and playback are
However, as described in FIG. 7, the phase of the control signal Sp during reproduction is determined by the signals Q, 3, Pv, and Ph. The phase must be as shown in FIG. 2A and C with respect to the signal Ss.

In order for the control signal Sr to have such a phase, as shown in FIGS. 9A and 9D, the output Q22 must be "1" in the field period Ta and in the horizontal period when the phase of the carrier color signal Ss is equal to 1. In addition, the phase of the field period eyebrow mb must be "1" during the horizontal period when the phase of the carrier color signal Ss is 0.

That is, the output Q22 has a phase of the carrier color signal Ss of 3.
Only one of the horizontal periods must have a phase that is "1" in a horizontal period that is different from the others. Therefore, the circuit that regulates the output Q2 to such a phase is the regulation circuit 1.
It is 30.

That is, in the gate circuit 131, the discrimination signal (unmodulated subcarrier) Si located on the back porch of the horizontal synchronization pulse Ph is extracted from the carrier color signal Ss, and this signal Si is applied to one input contact of the switch circuit 132. is supplied to the switch circuit 13 through the inverter 33.
2, and is also supplied to the other input contact of the FF circuit 122.
The output Q2 is supplied to the switch circuit 132 as its control signal, and when Q22="1", the switch circuit 132 is switched to the inverter 133 side, contrary to the diagram. Then, the output signal of the switch circuit 132 is supplied to the phase comparator circuit 134, and is also supplied to the delay circuit 135 to become a signal Sd delayed by two horizontal periods.This delayed signal Sd is supplied to the comparator circuit 134 and both Signal Si,
When there is a phase difference in Sd, a comparison output Pp which becomes "1" is taken out, and this world power Pp is sent to the FF circuits 121 and 12 through the gate circuit 136 and further through the OR circuit 138.
The signal is supplied to the clear terminal CL of No. 2.

Further, in this case, the gate circuit 136 is coupled with a control signal Sm from a gate control circuit, for example, a monostable multipipulator 137, and although the gate circuit 136 is normally on as shown in the figure, it outputs an When obtained,
From that point on, it is turned off for a period of, for example, just over three horizontal periods. Therefore, considering the field period Ta, at time t in FIGS. 10A to 10C, as shown previously, the output Q2 becomes "1" during the horizontal period when the phase of the output Q2 is correct and the phase of the signal Ss is equal. In this case, the time t of ○ in Figure 10,
As previously shown, a signal Si having a phase of 0 is taken out from the switch circuit 132 for each backport of the pulse Ph.

Since this signal Si is delayed by two horizontal periods in the delay circuit 135, the delayed signal Sd is also delayed by the 10th horizontal period.
At time t in Figure E, the phase is 0, as previously shown. Since the signals Si and Sd both have a phase of 0, the comparison output Pp of the comparison circuit 134 is "0" as shown before time t in FIG. 10F. Therefore, the output P
Even if p is supplied to the clear terminals CL of the FF circuits 121 and 122, the FF circuits 121 and 122 are not cleared, and the output Q2 maintains this phase state. Therefore, the correct phase state is maintained. continues. Further, the signal Sm also remains at "0" as shown before time t in FIG. 10G. As described above, as long as the phase of the output Q22 is correct, that state is maintained. However, suppose that the FF circuits 121 and 122 malfunction due to noise or the like, and as shown in FIG. 10C, Q22 becomes "1" one horizontal period earlier at time t.

Then, the phase of the signal Si (FIG. 10D) obtained from the switch circuit 132 at the beginning of time t becomes sharp, and
At this time, the phase of the delayed signal Sd is 0, so Pp="1
”, which is the gate circuit 136 and OR circuit 138.
The signal is supplied to the FF circuits 121 and 122 through the signal, and the FF circuits 121 and 122 are cleared. This clearing operation is the same as that by the output Q23 of the AND circuit 123,
This Pp="1" corresponds to the third pulse Ph in FIG. 8A.

Therefore, when the pulse Ph is supplied next, it corresponds to the first pulse Ph in FIG. At time t2, Q22 becomes "1", and from the time of the third pulse Ph, Q22 becomes "0". In addition, Pp becomes "1" at the time of the first signal Si after time t, and Sm becomes "1", and after a little over three horizontal periods, Sm
= “0”. Therefore, even if Pp becomes "1" during this period, this is blocked by the gate circuit 136 and the FF circuits 121 and 122 are not cleared. However, the output Q22
The phase of FF is not yet correct at time t3, and the phases of signals Si and Sd have changed in response to the change in output Q22, so Pp becomes "1" at time t4, and as a result, FF Circuits 121 and 122 are cleared again.

Therefore, since the pulses Ph after the time t4 correspond to the first to third pulses Ph, Q22 becomes "1" during the horizontal period when the phase of the signal Ss is at the lowest level. At this time, since Sm="1", the FF circuits 121 and 122 are not cleared even if Pp="1". Therefore, from the first signal Si after time t4, the output Q22 has the correct phase. in this way,
When the phase of the output Q22 is disturbed, a phase difference occurs between the signals Si and Sd, and Pp="1'1", thereby clearing the FF circuits 121 and 122, and correcting the phase of the output Q22.

If the field period Th' becomes difficult, consider reversing the phases 0 and w of the field period ma, and therefore, the phase of the output base can be correctly regulated.

As described above, the phase of the output Q22 is adjusted by the regulation circuit 13.
0' Therefore, the phase of the control signal Sr is regulated to the phase shown in FIG. 9A, D, and therefore the phase of the control signal Sr is regulated to the phase shown in FIG. 2A, C. Therefore, during reproduction, the phase shown in FIG. As shown in FIG. It can be attenuated.

Note that during recording, the signal Ss on the left side of FIG. 2A and the signal Sr on the right side of FIG. 2C are combined, and the signal Ss on the right side of FIG. 2A and the signal Sr on the left side of FIG. 2C are combined. may be combined, but in this case, the 0 barbs may be replaced in each signal, resulting in the same operation as described above.

Thus, according to the present invention, even if SECAM color video signals are recorded at high density as shown in FIG. 3, they can be reproduced without being affected by inter-track crosstalk.

It also has high color resolution, is less prone to overmodulation noise, and can reproduce beautiful color images. In addition, in the above,
The phase of the carrier color signal Sc is constant in any field period, for example, 0 in the field period Ta, amber in the field period Tb', and
Even if the carrier frequency fC is recorded with a difference of an odd multiple of 3fh so that they are interleaved with each other, it is sufficient to reproduce the reproduced carrier color signal Sc in the same way. It is sufficient to frequency-convert the frequency to a carrier color signal Ss using an alternating signal Sq, and then supply the signal Ss to the filter 54.

Furthermore, the azimuth angles of heads IA and IB do not have to be different from each other; in that case, for example, tracks 3A and 3B
Then, the frequency or phase of the FM luminance signals may be changed between tracks 3A and 3B so that they are interleaved with each other. Also, the oscillation circuit 7 is controlled by the AFC circuit.
The second oscillation signal may be synchronized with the discrimination signal Sj. Further, in the delay circuit 54D, the attenuator 54A may be omitted by attenuating the delayed signal.

Further, the filter 54 only needs to have a soft type Y-comb characteristic, and can be configured as a feedback type, for example. In addition, the period during which Sm="1" is set to a little over two horizontal periods, and as shown in FIG.
A control signal Sn that becomes "1" for one horizontal period like the signal Sm is obtained by the output Pp from 37, and the gate circuit 139 may be turned off when Sn="1" by this signal Sn.

[Brief explanation of the drawing]

Figure 1 is a system diagram of an example of this invention, Figure 2 is a diagram for explaining it, Figure 3 is a diagram showing its recording pattern, and Figures 4 and 6 are system diagrams of some examples thereof. , Figures 5 and 7
10 to 10 are waveform diagrams for explaining the same, and FIG. 11 is a partial system diagram of another example. 11 to 34 are recording systems, 41 to 56 are playback systems, 6 Kawama AF
C circuit, 8 Kawama head servo circuit, 100 is control circuit,
110 and 120' are control signal forming circuits, and 13 are phase regulating circuits. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 10 Figure 6 Figure 7... Figure 8 Figure 9 Figure 11

Claims (1)

[Claims] 1. The phase of the input carrier color signal is adjusted to the same phase for each track so that the carrier color signal of the SECAM color video signal is frequency interleaved between one and the other of adjacent tracks. a circuit for converting the frequency of the reproduced carrier color signal to be constant in each track section when reproducing the SECAM color video signal from a recording medium on which the frequency is controlled and recorded;
It has a delay circuit that delays the carrier color signal in the predetermined state by two horizontal periods, and an adder circuit that adds the delayed signal and the carrier color signal in the predetermined state at mutually different level ratios, A reproducing device for SECAM color video signals, which obtains a carrier color signal with attenuated crosstalk signals from this adder circuit. 2. The phase of the carrier color signal recorded on the first track is defined to be a constant phase, and the phase of the carrier color signal recorded on the second track adjacent to the first track is set to a constant phase.
SECA is performed by controlling the carrier color signals recorded on the first and second tracks to be frequency interleaved with each other.
From the recording medium on which the M color video signal is recorded, the S
When reproducing an ECAM color video signal, a circuit converts the phase of the reproduced carrier color signal so that it is constant in each track section, and a delay circuit delays the carrier color signal in a predetermined state by two horizontal periods. and an adder circuit that adds this delayed signal and the carrier color signal brought into the predetermined state at mutually different level ratios, and a carrier color signal with an attenuated crosstalk signal is obtained from this adder circuit. S
ECAM color video signal playback device.