JPS60132495A - Processor of color image signal - Google Patents

Abstract

PURPOSE:To prevent erroneous detection by preventing the switching operation by the delay time of a comb-shaped filter from the switching time point when the phase inversion of a burst signal is switched. CONSTITUTION:An output SI of an AND gate 69 rises at the time point of the front end of a horizontal synchronizing signal after two horizontal periods from the head of the next horizontal section where the first pulse of a sequence detection output comparison output DS is obtained, and therefore, the output SI becomes the signal which rises after about three horizontal periods when the first pulse of the comparison output DS is obtained. Since the rise is supplied to an FF circuit 64 as a clock signal, it rises at the low level at the time point after about three horizontal periods from the first comparison output DS, and it becomes the condition which is again set by following pulses of the comparison output DS. Therefore, a circuit 64 does not invert even if there is the pulse DS for about three horizontal periods from the first pulse of the comparison output DS. Thus, an FF circuit 39 is invertes by the rise of an output SE of the circuit 64.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is applicable to, for example, popular household VTRs and 8mm videos, in which a color video signal, a luminance signal is frequency-converted and sent to the western region, and a carrier color signal is While converting the frequency to the lower frequency side, the phase of the subcarrier is controlled and recorded, and a comb filter is used during playback to make it possible to remove the C crosstalk component of the carrier color signal from the adjacent trunk. The present invention relates to a color video signal processing device in a color video signal reproducing device.

BACKGROUND TECHNOLOGY AND PROBLEMS In the case of popular home VTRs and so-called 8mm video VTRs that are integrated with a camera, the luminance signal is FM-modulated to a relatively high band when recording a color video signal, and then transported. The color signal is frequency-converted to the lower frequency side and recorded.

By the way, when recording and reproducing PAL video signals using this VTR, it must be noted that one modulated color signal of the PAL carrier color signal is inverted every horizontal section. That is, as shown in FIG. 1, the carrier color signal of a PAL color video signal is F+ -(EB-Ey) →-j(ERE
y), and in the remaining every other horizontal interval, F−=
(Es Ey) j (ER-Ey), the phase of the modulation signal of the red color difference signal is inverted every horizontal interval, and correspondingly, B -Y
A burst signal B+ with a phase lead of 135° with respect to the axis is inserted, and a burst signal B+ with a phase lead of 135° with respect to the B-Y axis is inserted for the signal F-.
A burst signal B- with a delayed phase is inserted.

In performing color demodulation of this PAL system color video signal, when the color video signal reproduced from the V'I''R is supplied to the television receiver, one-sided processing is performed at every horizontal interval as described above. The phase of the modulated color signal, that is, the modulated signal of the red color difference signal, must be inverted every horizontal interval.

During VTR playback, the continuity of one turn of the modulated color signal is taken into account without any problems, but when the rotating head scans across multiple tracks during high-speed playback or slow-motion playback, etc. In such a case, the continuity of the inversion every l horizontal sections may be lost.

That is, FIG. 2 shows an example of a track pattern of a β format VTR compatible with PAL color video signals, in which every other track TAt.

T A 2 ... is the track recorded by the RAD HA on one rotation of the rotary head 211111,
TBl, TB2..., the other azimuth angle is head H
Tracks recorded by a rotary head HB different from A are shown, and arrows (1a) and <
lb) indicates the phase of each horizontal interval (1H) of the burst signal in the recorded carrier color signal. In addition,
The signals actually recorded are 4-1 between adjacent tracks.
For example, 1. 'f'A2..., the carrier color signal is recorded with the phase of the sub-II transmission wave reversed every horizontal interval, and the remaining every other trunk T +3 t, T
In B 2 ..., the subcarrier is recorded with the same phase, so the phase of the burst signal on the actual recording pattern is not a random one, but during playback, the trunk ""
This is a case in which the 'ζ phase is restored for At, TA2, . . . .

By the way, in this tape pattern, since the horizontal alignment of C is 1H, the color alignment of the PAL color video signal is not taken.

Therefore, in the high-speed playback mode, if the RAD HA rotates and scans a trajectory similar to that shown by the broken line in Figure 2, the playback signal is extracted from track T A 1 at point a in the figure. Track TA Jumps 2 degrees. Looking at the phase of the burst signal in the reproduced signal obtained by high-speed reproduction of The continuity (hereinafter referred to as burst signal sequence) is reversed. Therefore, if an attempt is made to reproduce a °C video by supplying such a PAL color video signal to a monitor receiver, correct colors will not be reproduced on the screen.・The above explained the case where PAL video signals are recorded and played back by a HATA-type VTR, but the so-called 8mm video standard also requires horizontal alignment of 1H or 2H, so color alignment is not taken. A similar problem arises.

Therefore, a processing device for a carrier color signal as shown in FIG. 4 was proposed.

This example is for 8mm video, and during recording, the carrier color signal in every other trunk is recorded with the subcarrier shifted by 90° for each horizontal section, and the remaining In every other column and rank, the subcarriers are recorded with the same phase.

In this example, in order to correct the reversal of the continuity of reversal for each horizontal section of one modulated color signal (red color difference signal) of the PAL signal, the carrier color correction based on the low frequency carrier color number is used. This is done by switching the frequency conversion signal used when converting the frequency into the sum and difference signals of the low subcarrier frequency fL and the original subcarrier frequency fse.

In Fig. 4, the signal regenerated by the two rotary heads is supplied to the regeneration amplifier (2) through the input #(1), and the output of this amplifier (2) is fed to the bypass filter (3).
)"M modulated luminance signal is taken out, and this is reproduced by P"MM demodulation "ζ".

Further, the output of the amplifier (2) is supplied to a low-pass filter (4), and a low-pass converted carrier color signal is taken out, which is supplied to a frequency conversion circuit (5). On the other hand, a variable frequency oscillator (11) is provided that generates a signal with a frequency equal to the low subcarrier frequency fL of the 1M color feeding signal that has been low-pass converted, and a signal with a frequency fL from the variable frequency oscillator (11) is provided. The signal is supplied to a phase control circuit (12), subjected to phase control as described later, and then supplied to a frequency conversion circuit (14).

On the other hand, the original P A L, the subcarrier frequency f H of the signal
C (= 4.43Mllz) reference oscillator (15)
The oscillation signal from is supplied to this frequency conversion circuit (14), from which the signal of frequency f, , c+rL and the frequency E
A signal of 5C-f is obtained. These are then extracted through band pass filters (16A) and (16B), respectively. Then, the signals from the band pass filters (16^) and (16B) are sent to the switch circuit (
18) is selectively taken out and supplied to the frequency conversion circuit (5).

In this frequency conversion circuit (5), ζ is the frequency f 5c4
-rL or the frequency conversion signal of frequency fscfL and the signal of low frequency conversion subcarrier frequency fL are multiplied, and only the signal of original frequency fsc + fL is extracted, and this is the frequency conversion circuit (5). is supplied as a frequency conversion signal.

In this frequency conversion circuit (5), the frequency r sc
10(L signal minus the low-pass converted subcarrier frequency f, so ζ original subcarrier frequency f SC = 4
, 43M llz is obtained, which is extracted via a bandpass filter (6).

In this case, the phase of the subcarrier is determined by the frequency conversion circuit (5) and the phase of the C frequency conversion signal is determined by the phase control circuit (12).
When the phase is changed, the phase shifted ζ is returned during recording. Zunawara, the phase control circuit (12
) is supplied with a control signal through the terminal (13), and the phase is shifted by 90° for each horizontal section. During playback from the trunk in which the 'ζ carrier color signal is recorded, ■variable frequency for each horizontal section. An operation is performed to shift the phase of the signal from the oscillator (11) by 90°, thereby restoring the phase of the subcarrier.

Incidentally, although the output of the bandpass filter (6) still contains crosstalk components from adjacent trunks, this is absorbed through the C-shaped comb filter (7) consisting of a delay circuit and a subtraction circuit in two horizontal sections. removed and the output terminal (8
) a crosstalk-free carrier color signal is derived.

In this case, the variable frequency oscillator (11) is
The APC is designed such that the free signal frequency has a constant relationship with the output frequency of the reference oscillator (15). That is, a part of the signal (a) passed through the comb filter (7) is supplied to the burst gate circuit (21) to extract a burst signal, which is supplied to the phase comparator circuit (24) and the reference oscillator (I5). ), and the comparison error voltage is filtered through a low-pass filter (
25) to the variable frequency oscillator (1) so that its oscillation frequency is controlled.

In this signal processing device, the sequence of burst signals as described above is corrected as follows.

That is, the output signal from the comb filter (7) is supplied to the burst signal sequence detection circuit (30), and it is detected that the burst signal sequence has been reversed in the following manner.

FIG. 5 shows an example of this sequence detection circuit (30), in which the signal that has passed through the comb filter (9) is phase-detected via a burst gate circuit (31) (which also serves as the burst gate circuit (21) and may also be ζ). The signal is supplied to the detection circuit (32). On the other hand, a signal from a reference oscillator (33) with a frequency f sc = 4 and 43M llz is supplied to one input terminal of the switch circuit (34), and is then phase-inverted and supplied to the other input terminal. And this switch circuit (34
) is the horizontal synchronization f from the flip-flop circuit (36)
At the time of No. M HD, the signal that inverts the state of 11Jl'OJ alternately switches between one input terminal and the other input terminal every horizontal section, and the output of this switch circuit (34) is sent to the phase detection circuit ( 32).

The phase of the signal from the reference oscillator (33) is, for example, the phase that coincides with the -(R-Y) axis as shown in FIG. Neo appears in Figure 3B. Therefore, when the sequence of the burst signal is stopped, as shown in FIG. 3C, a positive output signal is obtained from the phase detection circuit (32) at the time of the burst signal, and a If the ゛ζ sequence is reversed at a point, the phase detection circuit @ (
32) provides a negative output signal. The output DS of the phase detection circuit (32) thus obtained is supplied to the level comparison circuit (38) via the low-pass filter (37) and compared with the reference voltage ER. When the output of [1] is low, that is, when a detection output of negative polarity is obtained, a signal that rises to I' l J is obtained from this comparator circuit (38), and this rise of [1] causes the flip-flop circuit (39) is reversed. The output signal SW obtained from this flip-flop circuit (39) is fed as a switching control signal to the switch circuit (17).

Therefore, the switch circuit (17) is switched to the opposite side from the time when the sequence of the burst signals is reversed, and the state where the sequence is reversed is corrected.

By switching this frequency conversion signal, the subcarrier is inverted with respect to the BY axis).The Kyoto principle will be explained below.

Now, if the angular frequency of the low-frequency subcarrier is ωl, the angular frequency of the C subcarrier is ω2, and the reproduced II transmission false color phase is θ, then the frequency conversion signal is ′(ω2+ω1
When using the f-number, it is a frequency conversion IC! 1M & (
The output of sr (and therefore the output of the bandpass filter (6)) is as follows.

ω2→−ω+(ω1”−〇)ωω2−θNext, when using the signal ′Cω2−ω1 as the frequency conversion signal, it becomes ω2−ω1+(ω1”−θ)bow・ω2]−θ. , considering ζ and θ-〇 in the reproduced carrier color signal as the B-Y axis,
By converting this frequency conversion signal bIJ, the phase of the signal obtained by frequency conversion is inverted every time with respect to the BY axis.

Note that when the frequency conversion signal is switched in this way, the following problems occur.

That is, it is a change in the phase lock point of the APC loop.

The APC circuit works so that the two human input signals of the phase comparison circuit (24) have a phase difference of 90 degrees. The reference phase of the signal from the oscillator (15) is set to 0°
In this case, there are two cases: a case where the phase of the other human input signal is shifted by 90 degrees at phase point A, and a case where the phase of the other human input signal is shifted by 90' at phase point B.

For example, if there is a phase error in the low-pass conversion carrier color signal, when the frequency is converted by ω2 + ω1 as a frequency conversion signal, ω2 + ω1 - (ω + Δθ) → ω2 - Δθ Also, the frequency conversion signal If we transform by ω2-ω1, it becomes ω2-ωj + (ω1+80)-+ω2+Δθ,
The phase error will be in reverse phase.

APCII! The circuit works to eliminate phase errors at the output, so the output of the variable frequency oscillator (11) is ω1 + Δθ
Then, in the frequency conversion circuit (5), (ω2+ω1
+Δθ)−(ω1+Δθ)−CTω2 or (ω2−ω1−Δθ)+(ω1 +Δθ)−5ω2, and the phase error disappears. In other words, the oscillation output of the single variable frequency oscillator (11) is corrected in the same direction regardless of the switching of the switch circuit (17), and therefore the output of the phase comparison circuit (24) is also in the same direction. On the other hand, when the phase comparator circuit (24) is manually operated by °C1, when the frequency conversion signal is changed by switching the switch circuit (17), the phase error direction is in the opposite direction, so the phase comparator circuit (24) smells ζ is the switch circuit (17)
Due to this switching, there are two lock points, point A and point B, and the lock phase changes by 180 degrees, that is, is reversed.

This will not cause any problems unless processing such as 'ζ phase detection is done in the subsequent circuit when handling the signal at terminal 0ω. Since this circuit uses a phase detection method, it is inconvenient that the phase of the Iho signal obtained at the output terminal 00) is inverted. Therefore, in this example, ζ is the burst gate circuit (21) and the phase comparator circuit (21).
A switch circuit (22) is provided between the burst gate circuit (2I) and the burst gate circuit (2I). 'C is supplied to the other input terminal, and this switch circuit (22) is switched by the output SW of the sequence detection circuit (30) in synchronization with the switching of the switch circuit (17), so that the lock point is set to one. be made to be.

The circuit for this phase inversion processing is a comb filter (
9) and the burst gate circuit (21) and the output terminal a0, or may be provided in the signal path supplied from the oscillator (15) to the phase comparator circuit (24). Furthermore, it may be provided between the phase comparator circuit (24) and the variable frequency oscillator (11).

By the way, in the above-described correction of the continuity of inversion of the burst signal, cancellation of crosstalk from adjacent tracks regarding the carrier color signal component was not considered a problem in the above example. However, this crosstalk from adjacent tracks may not be canceled correctly during the delay time of the comb filter, resulting in the following drawbacks.

That is, when a discontinuity in the burst signal sequence occurs at point a of the above-mentioned Tora Noku Nogu turn as shown in FIG. 8A, the discontinuity in the sequence is detected after the comb filter. The inversion is performed from the time of the burst signal delayed by two horizontal periods or more.

In the case of No. 81g1A, 2H (IH
(1 horizontal section) At the time of delay, the Sui-Nona circuit (17)
is activated, and the state in which the inversion process has been performed is omitted. This Fig. 8A is the output of the bandpass filter (6),
The output of this bandpass filter (6) still contains crosstalk components.

This is shown in Figure 8B. In the example shown in the figure, in order to make the explanation easier to understand, the crosstalk component is shown as four squares so that it can be removed by addition in the comb filter. In this case, if the periods before and after the inversion point are considered separately, the crosstalk cancellation due to the shift performed every 90 degrees will be performed correctly. However, because the period from the discontinuity occurrence point a to the switching inversion point C is just over 2H, it is necessary to use the uninverted signal from 2H before ()-ζG immediately after the inversion. Crosstalk components are removed and 1'6
The remaining °ζ will come. That is, FIG. 8C shows the phase of the /\-strike signal of the carrier color signal of the tracker 1 to be scanned by the output signal of the 2H delay line of the comb-shaped letter (9), and・The crosstalk components from Tsuku are shown respectively. Therefore, the output signal ζ of this comb filter (9) is the original carrier color signal number and is in the correct state as shown in Figure E, but the crosstalk component becomes as shown in Figure F. In the figure FD, the circle not marked indicates that the crosstalk is canceled, and as is clear from this figure, the crosstalk component G remains uncancelled for a little over 2H from the point of reversal. I understand that. 1, the original signal becomes as shown in E in the same figure for the reference phase detection (phase No. 1 (G in the figure)) of the sequence detection circuit (30). (Despite the connection being made correctly, this crosstalk component is phase-detected and is incorrectly detected as a sequence reversal, and as shown in H in the same figure, this detection output causes an error at time a. After the inversion, a detection pulse is obtained again, and therefore the output signal of the solitube flop circuit as a switching signal is inverted, as shown in Figure I, and the switch circuit (17) is also switched. °C1 Eventually, the original signal sequence becomes reversed again.The sequence detection circuit (30) then detects this reversal again, and this continues alternately every time it occurs, causing an oscillation. This results in a shape like this, and the signal thread becomes unstable.

The above takes into account the continuity of the sequence in which one of the variable mJM color signals, which is unique to PAL signals, is inverted every horizontal period, but even in the case of NTSC signals, due to VTR skew, etc. A similar situation occurs in the burst ID circuit, which detects the phase inversion of the burst signal itself and detects the occurrence of the phase inversion of the burst signal.

That is, FIG. 9 shows a processing circuit for a carrier color signal in a VTR playback device having this burst ID circuit, in which the re-4 NTSC color video signal through the input terminal fil is passed through an amplifier (42) to a 'ζ low-pass filter ( 43), the low frequency converted carrier color signal is taken out, and is supplied to a frequency conversion circuit (44). That's it
ζ, similar to the PAL signal, this frequency conversion circuit (44) has nine subcarrier frequencies rsc and a low subcarrier frequency fL.
A signal having a frequency equal to the sum of fSC is supplied, and from this a carrier color signal with the subcarrier frequency returned to the original frequency fSC is obtained, which is extracted via a bandpass filter (45). This is then passed through a C-shaped comb filter (48) consisting of a delay circuit (46) for one horizontal period and a subtraction circuit (47) to remove crosstalk components, and is taken out to a T output terminal (49).

The signal for frequency conversion is subjected to APC and is formed as follows.

That is, a variable frequency oscillator (50) with a free-running oscillation frequency fL.
will be established. The carrier color signal that has passed through the comb filter (48) is then supplied to the burst signal circuit (51) to extract the burst signal, which is then passed through the phase comparator circuit (51).
52). On the other hand, the reference crystal oscillator (54)
The signal of frequency f SC from the phase comparator circuit (52
), the phases of the two are compared, and the comparison error output is supplied to the variable frequency oscillator (50) through a low-pass filter (53), so that its oscillation frequency is locked to the phase of the reproduced signal. . Then, the signal from the variable frequency oscillator (50) is supplied to the phase control circuit (55). During recording, the phase of the subcarrier is inverted every horizontal section and recorded on every other track. During playback from the oscillator (54), phase inversion processing is performed for each horizontal section.The signal from the phase control-R (55) is supplied to the frequency conversion circuit (56) and also to the oscillator (54).
) is supplied to this frequency conversion circuit (56), from which a signal of frequency fsc+fL is obtained, which is extracted via a bandpass filter (57). The signal passed through the bandpass filter (57) is supplied as is to one input terminal of the switch circuit (58), and is also supplied to the other input terminal of the switch circuit (58) through the inverter (59). This switch circuit (58) is connected to a burst 1D detection circuit (described later).
60), and when the burst signal phase is reversed by 180°, the switching state is reversed.

The Haas) ID detection circuit (60) is configured as follows.
There is. That is, the burst signal from the burst gate circuit (52) is supplied to the phase comparison circuit (61), while the oscillation signal from the reference oscillator (54) is phase-shifted by 90° by the 90° phase shifter (62). The signal is supplied to this phase comparator circuit (61). Then, the phase comparison error output of both is passed through a low-pass filter (63) (level comparison circuit (64)
When the output of the low-pass filter (63) becomes lower than the voltage ER',
The comparison output inverts the state of the flip-flop circuit (65). The output of this flip-flop circuit (65) is then supplied as a switching control signal to the switch circuit (58).

FIG. 10 is a diagram for explaining the burst 1D circuit, and A in the figure shows the phase of the burst signal in the carrier color signal reproduced and restored from the original trunk. In other words, at point 0 in the figure, the phase of the 'ζ burst signal is reversed due to the influence of skew, etc., and is in a state of "C".The crosstalk from the adjacent trunk at this time is C in the case of β format, but The signal is inverted for each horizontal interval, as shown in B in the same figure. Therefore, the signals obtained by delaying these signals by one horizontal interval become as shown in C and D in the same figure, and are passed through the comb filter (48). The signal output will be as shown in E and F of the same figure. Then, °ζ,
In this case, when the reference phase of the reference signal from the 90° phase shifter (62) is set to match the -(B-Y) axis as shown in G in the same figure, the phase comparator circuit (61) The output is as shown in F1 in the figure, and the output of the flip-flop circuit (65) is delayed by the delay time of the comb filter (48) from time 0, as in I in the figure. A discontinuous detection output is obtained, and the ζ sonar circuit (5 days) is inverted and switched accordingly.

Therefore, although the burst signal returns to the correct phase state after switching 1 in FIG. 10A, when switching in this way, crosstalk components may remain without being removed.

In other words, as shown in B, D, and F in the same figure, when the IQ is switched, the signal before the IQ switching is used to cancel the crosstalk, so this is not a continuous signal, and the crosstalk remains without being removed. When this happens, this crosstalk component is again regarded as an idle burst phase and detected by the burst ID output circuit (6o), and the solid flop circuit (65)
The switch circuit (58) is inverted again at the time of detection.
) will return to its original switching state and the burst phase will change again. Therefore, in this case as well, PAL
The state of the switch circuit (58) becomes unstable, just as in the case of a sequence of burst signals.

In the above example, the arrows for each phase shown in Figures 8 and 10 are schematic representations of the phases at the time of the burst signal. It is quite different from the phase. Therefore, the point of inversion is immediately after the detection output of the phase of the burst signal is obtained, so it has nothing to do with the horizontal synchronization signal.Actually, the phase of the burst signal is inverted in a certain horizontal section. If this were the case, the portion of the carrier color signal after that burst signal in that horizontal section would be permanently corrected.

In other words, the diagram shows the phase at the time of the burst signal because it is the m-wheel described in the explanation.

Purpose of the Invention In view of the above points, the present invention provides a change #1 of PAL color signal.
When correcting the continuity of phase inversion for each horizontal section of a single color signal, or in a burst 1D circuit for an NTSC portrait color video signal, the above-mentioned erroneous detection is avoided. L is what I'm trying to do.

Summary of the Invention In this invention, ζ is a change in one of the burst signals in the case of the PAL system. i When correcting the phase inversion for each horizontal section of the II color signal and switching the phase inversion of the burst signal by the burst 1D circuit of the NTSC color signal,
By preventing the supplementary operation and the switching operation by the delay time of the comb filter from the correction time and the switching time, the purpose is to prevent an erroneous supplementary operation from occurring.

Embodiment FIG. 11 shows an embodiment of the present invention, which is an example of an embodiment applied to the above-described sequence detection circuit (30) in a PAL color signal reproduction system.

In FIG. 11, ζ (61) is the horizontal synchronizing signal SA (first
This horizontal synchronizing signal S
A is converted into a signal SB (FIG. 13) whose phase is inverted from C through an inputter (62), and this is sent to an AND gate (63).
is supplied to one input end of the . On the other hand, the comparison circuit (38)
The sequence detection signal 1) S (C in the same figure) is supplied to the other input terminal of the AND CATE (63) of the car. Then ζ, the output SD of this anchor (63) (D in the same figure)
is supplied to the cent terminal of the solid flop circuit (64). The D terminal of this solid block circuit (64) is grounded, and when a human pulse is supplied to the clock terminal, its output SE (E in the figure) goes to low level.
However, when a pulse is supplied to the 'ζ set terminal while this output SE is at lll- level, the output SE (
E) in the figure stands at 11".

Therefore, this solid flop circuit (64) rises to l' l J at the first pulse of the sequence detection output SC. However, after that, it remains at 11'' unless a pulse is supplied to the clock terminal.

On the other hand, the horizontal synchronization output SA through the terminal (61) is supplied to the input terminal of the AND gate (65).

The output of the flip-flop circuit (64) is supplied as a gate signal to the other input terminal of this AND gate (65), and during its high level period, this AND gate (65)
), the output SF with the horizontal synchronization signal SA gated
(Figure F) is obtained from this.

Therefore, “C1 This anime game-1-(65) output SF
is in a state in which the horizontal synchronizing pulse is gated from the time when the comparison output DS of the sequence detection output is changed.

The output SF of this AND gate (65) is
Flip-flop circuits (67) and (6) constituting
8) is supplied to the clock terminal. These flip-flop circuits (67) and (68) are D-type flip-flop circuits. The counter (66) also includes an AND gate (69), and these D-type flip-flop circuits (
The Q outputs SG and SH (G and H in the figure) of (68) and (67) are supplied to the input end of this AND gate (69). In this case, the solid flop circuits (67) and (68)
are signals that are obtained by dividing the signal SF by 1/2, but their phases are different by 180 degrees, so the output Sl of the AND gate (69) is the 12th signal.
The signal becomes a low level for two horizontal periods, as shown in figure (2). This signal 31 is then supplied to the clock terminal of the flip-flop circuit (64).

As shown in FIG. 1, this signal S1 rises once at the leading edge of the horizontal synchronization signal two horizontal periods after the beginning of the next horizontal period in which the first pulse of the sequence detection output comparison output DS is obtained. Therefore, the first pulse of the ζ comparison output DS is obtained, resulting in a signal that rises after about three horizontal periods.

Then, ζ, since this rising edge F is supplied to the solid flop circuit vpi (64) as a clock fit signal, the output SE of this flip-flop circuit (64) is changed from the first sequence detection comparison output DS. After about 3 horizontal periods, it falls to low level and the comparison output D
A subsequent pulse of S causes it to be sent again. Therefore, for about three horizontal periods from the first pulse of the comparison output DS, this flip-flop circuit (64) will not be inverted even if there is a pulse l)S.

The output SE of this flip-flop circuit (64)
``ζ flip-flop circuit (39)
is inverted, and the ζ deviation becomes the detection output SW of the sequence detection circuit (30) as the switching signal of the switch described above.

Thus, according to the circuit of FIG. 11, once the first pulse of a sequence of discontinuous detection pulses occurs, that detection pulse is obtained during at least two subsequent horizontal periods, and ζ is also prohibited. Therefore, as mentioned above, suppose that erroneous detection occurs in these two horizontal sections due to crosstalk components from adjacent trunks of the carrier color signal due to the influence of the delay time of the comb filter. However, this also eliminates the possibility of an erroneous switching state.

In the embodiment shown in FIG. 11, the “ζ comparison output pulse DS
by the horizontal synchronization signal @ (63) using ゛ζ
The reason for this is that if the output time of the pulse DS overlaps with the horizontal synchronization pulse for some reason, this first horizontal synchronization pulse will be counted by the counter (66), so the pulse DS is inhibited. The period of time is not about 3 horizontal sections but more than 2 horizontal sections ζ
This was provided to prevent this from happening.

The above example explained the case of a PAL color signal, so the inhibiting period was 2 horizontal periods, but N
When applied to a burst ID circuit for TSC signals, this may be for at least one horizontal period. This is because the delay time of the comb filter is one horizontal period.

If it is applicable to this burst 1D circuit, a circuit similar to that shown in Fig. 11 (however, the inhibiting period may be two horizontal periods) can be provided between the comparator circuit (64) and the flip-flop circuit (65). good.

Note that the circuit for inhibiting the sequence detection output by at least the delay time of the comb filter is not limited to the above-mentioned configuration using a counter. Of course ζ is also good. However, when configured as described above, there is an advantage that stable operation is possible without the influence of noise when configured with a monostable multivibrator.

Effects of the Invention According to the present invention, when it is detected that the signal sequence is incorrect in burst 4 and that the phase inversion of the burst signal of the NTSC signal has occurred, the control is performed to correct each of them. , its '+l; It is possible to eliminate the influence of crosstalk components occurring during the delay time of the comb filter from the control point, and to perform a stable inhibition operation.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the PAL color video signal, Figure 2 is a diagram for explaining the PAL color video signal.
The figure is a diagram for explaining that discontinuity occurs in the sequence of burst signals of PAL signals, FIG. 3 is a diagram for explaining this, and FIG. 4 is a block diagram of an example of a circuit that prohibits discontinuity in the sequence. , FIG. 5 is a block diagram of an example of the main part of the circuit in FIG. 4, FIG. 6 is a diagram for explaining FIG. 5, and FIG.
8 is a diagram for explaining the disadvantages of the circuit in FIG. 4, FIG. 9 is a block diagram of an example of an NTSC color video signal reproducing device, and FIG. 10 is a diagram for explaining FIG. 4. 11 is a block diagram of an example of a main part of the circuit of the present invention, and FIG. 12 is a waveform diagram for explaining the same. - (30) is a burst signal sequence detection circuit, (6
0) is a burst ID detection circuit, (5) and (44) are frequency conversion circuits for converting the low frequency conversion carrier color signal back to a signal of the next subcarrier frequency, and (18) and (58) are sequence stop circuits. (64) is a flip solo block circuit for inhibiting the sequence detection pulse by at least the delay time of the comb filter; (66) is a switch circuit for correcting the burst signal phase.
is a counter for forming the inhibiting period. Same as Hidemori Matsukuma, l:1. :, □2: Figure 9 Figure 10

Claims (1)

[Claims] The luminance signal is FM-modulated, and the carrier color signal is frequency-converted to the lower frequency side of the FM-modulated luminance signal and recorded, and the phase of the subcarrier is shifted by a predetermined phase amount at a predetermined timing. At the time of reproduction of the recorded data, the reproduction system of the carrier color signal is provided with a frequency conversion circuit for converting the subcarrier frequency fL of the low band carrier color signal to the four subcarrier frequencies rsc. The carrier color signal returned to the subcarrier frequency rsc from the frequency conversion circuit is passed through a comb filter to remove crosstalk components from adjacent tracks, and the frequency of the frequency conversion circuit is A circuit is provided to detect a change in the phase of the berth I signal in the carrier color signal returned to ζ9 as a conversion signal, and a change in the continuity of inversion with respect to a specific phase axis, and the detection output is used to perform the frequency conversion. The switching signal is switched to a signal of the sum and difference of frequencies fllc and fL, and the switching is prohibited for at least a period corresponding to the delay time of the comb filter from the switching point, even if the detection output is present. Color video signal processing device.