JPS5946158B2 - Jitter correction method for video playback equipment - Google Patents

Description

[Detailed description of the invention] Problems of the present invention The present invention relates to a jitter correction method for a video playback device.

In particular, the present invention relates to a jitter correction method for a video playback device including a pseudo composite video signal generation device.
DESCRIPTION OF THE PRIOR ART The reproduction of a television image on the screen of a television receiver in accordance with a composite video signal reproduced by a video reproduction device, such as a video disc, tends to produce jitter. As a result, weeping of the television image is observed along the vertical direction.

This jitter is controlled by an automatic frequency control system installed in a normal television receiver by extracting the phase of the composite video signal supplied from the video playback device to the television receiver and the horizontal synchronization signal of the composite video signal. (hereinafter AF
This occurs according to the phase difference between the horizontal deflection signal and the phase of the horizontal deflection signal passed through the signal C. This phase difference between the composite video signal and the horizontal deflection signal is caused by the fact that AFC electrically stabilizes the frequency of the horizontal deflection signal, whereas the video playback device stabilizes the frequency of the horizontal deflection signal based on its structural characteristics. This occurs in television receivers because the composite video signal is reproduced from the television signal recording medium with a very low accuracy with respect to the reproduced signal phase. Therefore, in a television receiver having a structure in which the AFC time constant can be easily adjusted to a small value from the outside, the jitter appearing on the screen can be reduced relatively easily. However, like many television receivers already in common use in households, the AFC time constant cannot be adjusted. When used as a monitor television receiver for playback, the AFC time constant changing method described above requires modification of the monitor television, so it cannot be adopted mainly from the viewpoint of serviceability. . US Pat. No. 3,681,522 discloses a jitter correction method that can easily remove the jitter described above without making this modification. This technology does not directly supply the reproduced composite video signal to the monitor television receiver, but instead of the reproduced horizontal synchronizing signal contained therein, the reproduced horizontal synchronization signal is used to avoid the above phase difference. A modulated horizontal synchronization signal obtained by phase modulating the synchronization signal is used, and the converted composite video signal is supplied to a monitor television receiver. In other words, the above-mentioned U.S. patent essentially relies on the phase difference between the composite video signal supplied to the display tube of a monitor television receiver and the output signal from the AFC included in said receiver. The horizontal periodic signal of the reproduced composite video signal is phase modulated by an amount corresponding to , and the phase difference is compensated in advance on the part of the video reproduction device. Comparing the above method of changing the AFC time constant of a monitor television receiver with the method of pre-compensating for the phase difference in a video playback device disclosed in the above US patent, the latter method: The former method is superior in that it can completely compensate for the phase difference in question, whereas the former method cannot reduce the phase difference to zero. In the jitter correction method disclosed in the above US patent, the modulation signal that phase-modulates the horizontal synchronization signal of the reproduced composite video signal in order to minimize jitter has the frequency characteristics of AFC provided in the monitor television receiver. The system must be adjusted to better respond. If the AFC frequency characteristics of the receiver are known in advance, the AF
Although it is easy to design a means for adjusting the jitter correction means that deals with the AFC frequency characteristics, the current television receivers that are widely used in general households have various AFC frequency characteristics. Therefore, it is not necessarily easy to provide adjustment means for a jitter correction method that can be applied to each individual item. The above-mentioned US patent does not disclose adjustment means that can be adapted to AFCs having different frequency characteristics of different types of television receivers. In other words, there is room for improvement in the US patent for practical use. SUMMARY OF THE INVENTION In summary, the present invention provides a method for connecting any standard television set to a monitor television receiver equipped with AFC. A video reproducing device for reproducing a composite video signal of the monitor television system is equipped with a jitter correction method, and the composite video signal supplied to the display tube of the monitor television receiver is combined with the AFC output signal of the monitor television receiver. means for phase modulating the horizontal synchronization signal of the reproduced composite video signal by an amount related to the phase difference and presenting the transformed composite video signal as a phase modulated horizontal synchronization signal, characterized in that: In order to provide a pseudo composite video signal to the monitor television receiver through the jitter correction method, the horizontal synchronization signal includes a vertical and horizontal synchronization signal and a mark signal existing in the phase range of the video signal, and the horizontal synchronization signal is used in the standard television system of the video playback device. means for generating a pseudo-composite video signal that is shifted in phase relative to a horizontal synchronization signal of the apparatus, whereby the phase modulating means is configured to generate a pseudo-composite video signal by observing a mark indicia on the display tube screen by the mark signal; The present invention relates to an adjustable jitter correction method for a video playback device.

In a preferred embodiment of the present invention, the horizontal synchronization signal is
It consists of two types of horizontal synchronizing signals, one of the leading type and the other of the lagging type, so that two indicators appear on the display tube screen.

Adjustment of the phase modulation means is therefore more easily accomplished by bringing the two markers closer together.
The phase-leading horizontal synchronization signal and the phase-lag horizontal synchronization signal are pseudo-composite video signals in which one field of the phase-lead horizontal synchronization signal and one field of the phase-lag horizontal synchronization signal appear alternately in a filter sequence. Preferably, the two marking lines generated by the marking signals intersect at a position away from the top or bottom edge of the display tube screen of the television receiver. The start point of the filter is shifted from the vertical sync signal so that the characteristics and adjustment status of the AFC can be easily observed on the screen. Such a pseudo composite video signal can be prerecorded on a recording medium of a video playback device, such as a videotape or a video disc.

Alternatively, such a pseudo-composite video signal may be generated by an electrical circuit serving that purpose.
Such a circuit can be constructed relatively easily. Therefore, the main object of the present invention is to provide a jitter correction scheme for a video playback device comprising a jitter correction circuit with adjustment means that can be easily adapted to the AFC of a monitor television receiver.

Furthermore, the present invention provides a video playback device comprising a jitter correction circuit having adjustment means, whereby the adjustment of said adjustment means can be made easy and simple by the user while observing a display tube screen of a monitor television receiver. This provides a jitter correction method. Furthermore, the present invention provides an adjustment means and a pseudo for displaying on the display tube screen of the monitor television receiver the individual adjustment states of said adjustment means in relation to the timeliness of the AFC of the monitor television receiver. It is an object of the present invention to provide a jitter correction method for a video reproducing apparatus comprising pseudo composite signal generating means for generating a composite video signal.

Furthermore, the present invention provides means for phase modulating a horizontal synchronizing signal of a reproduced composite video signal, means for adjusting the amount of phase modulation, and a pseudo composite for displaying the adjustment process of the adjusting means on a screen of a display tube. said phase modulating means includes means for detecting one jitter component of a reproduction synchronizing signal, and said one jitter component detecting means is of a speed detection type, that is, a type that detects a time differential of a phase change. Therefore, it is an object of the present invention to provide a jitter correction method for a video playback device that improves the frequency characteristics of a jitter detection signal. The invention further provides means for phase modulating the horizontal synchronization signal of a reproduced composite video signal, and a pseudo device for producing an indicator on the screen of a display tube of a monitor television receiver indicating the adjustment status of said phase modulating means. means for generating a composite video signal, the phase modulation means comprising means for detecting a jitter component of a reproduced synchronization signal, the jitter component corresponding to a trailing edge of a reproduced horizontal synchronization signal provided in the reproduced composite signal; It is an object of the present invention to provide a jitter correction method for a video reproducing apparatus, which is adapted to perform detection based on a pulse train, thereby improving the accuracy of a jitter detection signal. These and other objects and configurations of the present invention,
The advantages and the full scope will become clearer from the following detailed description taken in conjunction with the accompanying drawings. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows one embodiment of the jitter correction method according to the present invention.

Basically, this embodiment includes a jitter correction circuit JCC connected between a video base device RA such as a video disk player and a monitor television receiver T. The input of the jitter correction circuit JCC is connected to receive a pseudo-composite signal from a pseudo-composite video signal generator PSG. Although the pseudo composite signal generator PSG is prepared independently of the video playback device RA and the jitter correction circuit JCC of the illustrated embodiment, this generator PSG is connected to the jitter correction circuit J in the form of an electric circuit.
It may be provided in the CC, or it may be provided in the video reproducing apparatus VRA in the form of a recording medium on which a pseudo composite video signal is recorded, as will be described in more detail below. A composite video signal reproduced from a video reproduction device VRA is supplied to the jitter correction circuit JCC. For details,
The jitter correction circuit JCC includes a sync signal separation circuit 1 for separating the horizontal sync signal from the reproduced composite video signal, a sync signal removal circuit 2 for removing the horizontal sync signal from the reproduced composite video signal, and a sync signal removal circuit 2 for removing the horizontal sync signal from the reproduced composite video signal. A horizontal synchronization signal phase modulation circuit 3 for phase modulating the horizontal concave period signal, a video signal from which the horizontal synchronization signal has been removed from the synchronization signal removal circuit 2, and a phase-modulated horizontal synchronization signal from the horizontal synchronization signal phase modulation circuit 3. A mixing circuit 4 is provided for mixing the signals and presenting a composite video signal that is phase modulated with respect to the horizontal synchronizing signal. On the other hand, the monitor television receiver is supplied with a video signal system including an amplifier 5 for amplifying the composite video signal and providing the amplified signal to a display tube 6, and a composite composite video signal. a horizontal synchronizing signal separator 7, an AFC 8 to which the separated horizontal synchronizing signal (phase modulated as described above) is supplied, and an O deflection circuit whose output is supplied to drive the horizontal deflection coil of the display tube 6. 9 and a deflection system. The AFC 8 of the monitor television receiver includes a voltage-controlled oscillator 10 that oscillates near the horizontal frequency;
a phase comparator 11 that compares the phase of the separated (phase modulated) horizontal synchronizing signal and the output of the voltage controlled oscillator 10;
and an integrator 12 for detecting an average level of error for controlling the voltage controlled oscillator.

If the open loop transfer function of AFC8 is F(S), then as is well known, the input signal phase ψIO and the output signal phase ψo
The following equation holds between . In addition, the open-loop transfer function F(S
) is expressed as follows in terms of the frequency characteristic G(S) of the integrator including the gain of the voltage controlled oscillator and the phase comparator.

F(S)=G(S)/S...2 The horizontal synchronizing signal phase modulation circuit 3 has its transmission F(S) function C
Is (S) the closed-loop transfer function of this AFC? 1+F(S)
The configuration is such that it can be adjusted to be equal to the reciprocal of , thereby eliminating the phase difference between the composite video signal supplied to the display tube 6 and the output signal from the AFC 8.

Ultimately, the phase modulation circuit 3 has its transfer function C(S)
is constructed as expressed by the following equation. In formula 3,
A circuit configuration for achieving the component S can be realized by using a speed detection type jitter detection circuit that detects the time differential of the phase fluctuation of the separated horizontal synchronizing signal for jitter detection.

Also, the circuit configuration that achieves component unity is its transfer function E(
This can be realized by using an amplitude and phase adjustment circuit that can adjust S)G(S) so that E(S)=Rerow(S).

The horizontal synchronizing signal phase modulation circuit 3 basically includes a speed detection type jitter detection circuit 13, an amplitude and phase adjustment circuit 14, and a phase modulator 15 connected as shown in the figure. Consisted of. FIG. 2 shows an embodiment of a speed detection type jitter detection circuit 13 with excellent frequency characteristics.

This detection circuit includes a preprocessing circuit 16 for removing a horizontal synchronizing signal near the vertical synchronizing signal, as described below, a voltage controlled oscillator 17 that oscillates near the horizontal frequency, and an output from this voltage controlled oscillator. an integrator 18 for integrating
, a sampling circuit 19 for sampling the output from the integrator 18 using the output from the preprocessing circuit 16, a holding circuit 20 for holding the output from the sampling circuit 19, and a voltage control signal from the holding circuit as a control signal. A circuit connection 21 provides an output to the oscillator 17, and a circuit connection 22 deduces a jitter detection signal from the holding circuit. The above-mentioned preprocessing circuit 16 includes a differentiation circuit 23 that differentiates the reproduced horizontal normal signal in the separated synchronization signal.
, a level detection circuit 24 that detects the level of the differential output from the differentiating circuit 23 at a predetermined level of the differential output, and a vertical sync signal separator that separates the vertical sync signal from the separated sync signal obtained from the sync signal separator 1. It includes a circuit 25 and a randomization gate 26 that performs randomization processing on the output of the level detection circuit and the separated vertical synchronizing signal.

With respect to FIG. 3A, which shows the waveform of a composite video signal actually played back from a video playback device such as a video disc player, the played composite video signal has a leading edge (falling edge b portion a) of the horizontal synchronization signal. ) and the trailing edge (rising part b) of the horizontal synchronization signal, it is observed that the sharpness of the leading edge of the horizontal synchronization signal is inferior to that of the trailing edge.

The reason for this is that the frequency band of the video signal in a video disc player is limited, so the waveform is raw at parts where sudden changes occur, and the video signal is not constant until immediately before the leading edge of the horizontal synchronization signal. It is thought that the sharpness of the leading edge is inferior as a result of the sudden change due to its presence. Therefore, in order to detect jitter, it is better to obtain a pulse formed from the trailing edge of the horizontal synchronizing signal with good sharpness, that is, a pulse train corresponding to the trailing edge pulse of the horizontal synchronizing signal, for more accurate operation. You can expect it. FIG. 3B is a signal waveform diagram in the vicinity of vertical blanking of each part of the preprocessing circuit 16 shown in FIG. 2.

Regarding the waveform of FIG. 3B, if the horizontal synchronization signal is
Two pieces are included in the horizontal scanning period 1H. In this specification, to simplify the explanation, the period including the front equivalent pulse, the vertical synchronization pulse, and the rear equivalent pulse will be collectively referred to as a "vertical synchronization signal section" hereinafter. Because the cycle of the pulses obtained from the trailing edge of the reproduced horizontal sync signal during the above-mentioned "vertical sync signal section" is different from that of the pulses obtained in other parts of the reproduced composite video signal, It can be seen that in order to detect jitter based on the pulse train corresponding to the trailing edge, it is necessary to remove the pulses corresponding to the trailing edge of the horizontal synchronizing signal in the section of the vertical synchronizing signal section described above. The pre-processing circuit 16 mentioned above is for accomplishing the above purpose. The detailed operation of this preprocessing circuit will be explained below with reference to the waveforms shown in FIG. 3B. 3rd B
The differential circuit 23 to which the separated synchronization signal shown in waveform a in the figure is input derives a differentiated output shown in waveform b in the figure.

The differential output is input to the level detection circuit 24, where the output portion above the level indicated by the broken line of waveform b in the same figure is 0.
is detected, and a signal shown in waveform C in the figure is derived as its output. On the other hand, the vertical synchronization signal separation circuit 25 serves to separate the vertical synchronization signal shown in waveform d in the figure from the separated synchronization signal input thereto. The vertical synchronization signal is separated with a slight delay from the actual vertical synchronization signal because the vertical synchronization separation circuit usually includes an integrating circuit therein. The NAND gate 26, which receives the output from the level detection circuit 24 and the separated vertical synchronization signal, exhibits an output shown in waveform e in FIG. 3B. It is observed from waveform e that only the pulse corresponding to the trailing edge of the reproduced horizontal synchronization signal occurring in the section of the vertical synchronization signal portion mentioned above is removed. In this way, a pulse train corresponding to the trailing edge of the reproduced horizontal synchronizing signal from which the reproduced horizontal synchronizing signal generated in the vertical synchronizing signal portion described above has been removed is derived as an output from the preprocessing circuit 16 and is supplied to the sampling circuit 19. Ru. Now, regarding the operation of deriving the jitter detection signal based on the output from the preprocessing circuit 16, the waveforms of FIG. 3C showing the signal waveforms at blocks 17, 18, 19, and 20 of the circuit of FIG. Refer to and explain.

The oscillation output from the voltage controlled oscillator 17 (waveform a in FIG. 3C) is input to the integrating circuit 18, and an integrated output as shown in waveform b in the figure is derived. This integrated output is the above-mentioned pulse train (waveform C in Fig. 3C) corresponding to the trailing edge of the regenerated horizontal synchronization signal of residual power after removing the regenerated horizontal synchronization signal in the section of the vertical synchronization signal portion described above, and is generated by the sampling circuit. Sampled by 19. The sampled output is sent to the holding circuit 20
The held output of waveform d in FIG. 3C is fed back to the voltage controlled oscillator, and the amplitude,
It is input to the phase adjustment circuit 14 through circuit connection 22 .
Next, the above-mentioned amplitude and phase adjustment circuit 14 will be explained in detail.

Frequency characteristics G of the integrator including the gain of the above-mentioned voltage-controlled oscillator and phase comparator in the monitor television receiver TV
(S) generally exhibits frequency characteristics as shown in FIG. 4A. Therefore, the frequency characteristics of the transfer function E(S) of the amplitude and phase adjustment circuit 14 must be adjusted as shown in FIG. 5A. From a practical point of view, the falling part of the characteristic curve shown in Figure 4A in the high frequency region can be ignored;
Therefore, the frequency characteristic G(S) of the integrator including the gain of the voltage controlled oscillator and phase comparator shown in FIG. 4A can be regarded as shown in FIG. 4B. Therefore, the amplitude and phase adjustment circuit 140
The transfer function E(S) may be selected for practical reasons as shown in FIG. 5B. In FIG. 4B, if the levels at frequencies f1 (=-) and F2 (=?)2πTO2πα0T0 are respectively KO and DOKO, then the transfer function G (
S) is expressed in JC as follows.

Therefore, the transfer function E(S) of the amplitude and phase adjustment circuit must be expressed as follows.

Here, DO, KO, and TO are constants that are determined when the frequency characteristics of the integrator including the gains of the voltage-controlled oscillator and the phase comparator are specified.

Therefore, if the frequency characteristics of the voltage-controlled oscillator and the integrator, including the gain of the phase comparator, are not specified,
As is clear from the above formula 5, the amplitude and phase adjustment circuit 14
The variable parameters that must be adjusted in α0. Variables D, Kl and T related to K0 and TO
It is.

In order to determine these three parameters, in principle,
It is necessary to measure the frequency characteristics of the characteristic G as shown in FIG. 4A or FIG. 4B over the entire frequency range and determine α, K1, and T from the frequency characteristics. Further, in accordance with these parameters, the above-mentioned amplitude and phase adjustment circuit 14 must be configured to have a transfer function E(8) that satisfies the above-mentioned formula 5. It is absolutely impossible to perform the above-mentioned work on television receivers already installed in ordinary households, and it is extremely difficult to put it into practical use. In this regard, the previous US patent leaves room for improvement. On the other hand, in order to be able to appropriately deal with the AFC characteristics of a monitor television receiver while visually observing the display tube screen of the monitor television receiver without being conscious of the frequency characteristics of the AFC, the above-mentioned vibration Width and phase adjustment circuit 14
It would be very convenient if we could adjust this.
The present invention achieves this objective as detailed below. 30H for an NTSC video disc player that rotates the video disc at 30 revolutions per second.
It has been observed that one component of jitter below Z is almost imperceptible to a person observing the display tube screen of a monitor television receiver.

It is also known that due to the structural characteristics of this type of player, it is dominated by one jitter component of 30Hz and its harmonics. The AFCs of various monitor television receivers whose characteristics are unknown can be categorized based on the position on the characteristic curve of the above-mentioned frequency of 30Hz, and the characteristics shown in Figure 4 can be obtained. The characteristic curve A,bl
and c.

In other words, the above-mentioned 30Hz frequency is in the flat part of the high frequency range as shown in characteristic curve a, in the slope part of the intermediate frequency range as shown in characteristic curve b, and in the flat part of the low frequency range as shown in characteristic curve c. There are three typical cases in the section. Since the jitter component below the frequency of 30 Hz can be ignored from a practical standpoint, as described above, each characteristic in FIG. 4C corresponds to A. in FIG. 4D. bl and c can be substituted.

Therefore, the transfer characteristics required of the adjustment circuit 14 corresponding to the characteristics shown in FIG. 4D are the characteristics a'. shown in FIG. 5C. B5
, and c'. Therefore, the adjustment circuit 14 is configured such that the parameter K at 30Hz corresponds to the value Kl, K2 or K3 of a monitor television receiver of the type corresponding to the characteristic curve A, b or c classified as above. If adjusted to , the 30 Hz jitter component can be made invisible on the display tube screen of the corresponding monitor television receiver. This parameter KO adjustment can be performed by adjusting the amplitude adjustment circuit 14A of the amplitude and phase adjustment circuit 14, and also by adjusting the parameter d.
The TO adjustment is performed by adjusting the phase adjustment circuit 14B of the amplitude and phase adjustment circuit 14. Next, a description will be given of how the parameter K corresponding to the above-mentioned 30Hz jitter component is observed on the display tube screen of the monitor television receiver, and how the parameter K is adjusted.

For conditioning, the present invention employs a pseudo-composite video signal specially prepared for conditioning and jitter-corrects it so that said pseudo-composite video signal is displayed on the display tube screen of a monitor television receiver. The signal is input to the signal input terminal of the circuit JCC, and the adjustment circuit 14 is adjusted while visually observing the image on the display tube screen. FIG. 6 shows the waveform of the above-mentioned pseudo composite video signal in which the vertical synchronization signal train is compressed on the time axis,
FIG. 7 shows the waveform of the pseudo composite video signal in which the horizontal synchronization signal sequence is expanded on the time axis.

6 and 7, the pseudo-composite video signal of the illustrated embodiment has a predetermined time τ after each vertical synchronization signal. That is, for each area A and B in FIG. 6, the repetition period of the horizontal synchronizing signal is (H - δH), and the first mark signal is placed at a predetermined position, for example, at the center of each line of the first adjustment signal. P1 is added to the first adjustment signal, and the horizontal synchronization signal has a repetition period of (H+δH), and a second mark signal P2 is added to a predetermined position thereof, for example, at the center of each line of the second adjustment signal. It is constructed by alternately combining the second adjustment signal and the second adjustment signal. The positions of the first and second mark signals are generally determined from the horizontal synchronization signal of the first adjustment signal to the first mark signal P,
The ratio of the repetition period (H-δH) of the horizontal synchronizing signal of this first adjustment signal to the time t1 until the second adjustment signal to the time T2 from the horizontal synchronizing signal of the second adjustment signal to the second mark signal P2 is The repetition period of the horizontal synchronization signal (H + δ
The position is chosen to be equal to the ratio of H). In FIG. 1, a pseudo-composite video signal generator PSG is configured to generate the above-mentioned pseudo-composite video signal shown in FIGS. 6 and 7. The pseudo composite video signal generator PSG will be described in more detail later. When the above-mentioned pseudo composite video signal is input to the monitor television receiver TV through the jitter correction circuit JCC, a set of lines as shown by solid lines and dotted lines in FIG. 8 appears on the display tube screen of the monitor television receiver. revealed above.

Since the horizontal period of the first adjustment signal portion is shorter than that of the standard horizontal period, the mark generated by the mark signal P1 of the first adjustment signal moves from the upper right area to the lower left area on the screen, as shown by the solid line. Take a tendency to extend. On the other hand, since one horizontal period of the second adjustment signal portion is longer than the standard horizontal period, the mark caused by the mark signal P2 on the screen extends from the upper left area to the lower right area on the screen, as shown by the dotted line. take the existing tendency. However, since the monitor television receiver is equipped with AFC, the monitor television receiver operates to perform horizontal deflection in synchronization with a phase-shifted horizontal synchronization signal according to the characteristics of the AFC.
Thus, the mark signal P of the pseudo composite video signal,
The marker line produced by P2 and P2 tends to be bent to extend vertically according to the AFC characteristics of the monitor television receiver. ．． The combination of these lines indicates the AFC characteristics of the monitor television receiver, and the AF
Corresponds to the step response of C. Consequently, the AFC characteristics of a monitor television receiver can be determined by looking at the receiver's display tube screen. In order to adjust the adjustment circuit 14 of the jitter correction circuit JCC, it is sufficient to adjust the above-mentioned lines so that they are close to each other as shown in FIG. 8B. In the illustrated embodiment, the first and second adjustment signals for each field are τ from the vertical synchronization signal. The two marker lines on the screen are phase shifted by the time τ. It appears at a position on the screen away from the middle of the frame or the bottom edge of the screen, depending on the location. It is desirable to locate the intersection of these two lines near the center of the frame on the screen because the intersection can be easily observed. 2. As shown in FIG. 8B, the width W between the two lines appearing on the screen can be widened or narrowed by adjusting the width adjustment circuit 14A, and the width W can be set to a minimum When the above parameter K is set to the AFC corresponding parameter Kl. which is specific to the adopted monitor television receiver. K
2, 1 or K3. As shown in FIG. 8C, a case may occur in which the solid line and the dotted line do not partially match each other, which is different from the case in FIG. 8B. This occurs when the above-mentioned phase adjustment circuit 14B is not properly adjusted. Next, a specific example of the phase adjustment circuit 14B will be explained.

According to Haramoto, this phase adjustment circuit 14B can have any configuration as long as it satisfies the above formula 5, but considering the convenience of adjustment operation, the previously set parameter K
However, it is desirable to have a configuration in which the parameters α and T are not changed during the adjustment process. Figures 9A1, 9B1 and 9C are:
10A, 10B1, and 10C show frequency response characteristic diagrams of each corresponding circuit.

The transfer characteristic of the first adjustment circuit shown in FIG. 9A is expressed by the following equation.

Select Cia so that f(1-1)a=C(1-1)a/Cia=constant.

The transfer function of the second adjustment circuit shown in FIG. 9B is expressed by the following equation.

Therefore, by using the above-mentioned pseudo composite video signal, the jitter correction circuit JCC (D
Adjustment is very easily achieved.

Next, the pseudo composite video signal generator PSG will be explained in more detail. Very practically, the pseudo composite video signal described above with reference to FIGS. 6 and 7 is recorded on a recording medium such as a video disk or a video tape, especially a recording medium for viewing. In this embodiment, the recording medium is set in a video playback device VRA for video playback.The playback pseudo composite video signal thus obtained is sent to a jitter correction circuit JC.
The signal is input to the monitor television receiver TV through C. In this embodiment, it can be seen that the pseudo-composite video signal generator PSG is included in the video reproduction device VRA. In this embodiment, it is also possible to provide an explanation on how to adjust it before the area where the pseudo composite video signal is recorded, and in that case, the user can easily and easily make adjustments according to the explanation. be able to. Separately, the first and second adjustment signals described above can be easily obtained by imaging with a flying spot skinner that alternately scans vertical lines at periods (H-.delta.H) and (H+.delta.H). In the embodiment described, the pseudo-composite video signal is comprised of a pair of conditioning signals, first and second conditioning signals a and b, described in connection with FIG. This embodiment is the most preferred type in which the two marker lines are adjusted to be close to each other. Alternatively, only one adjustment signal may be used for adjustment according to the invention. Furthermore, the phase difference between the starting point of each adjustment signal and the vertical synchronization signal may be set to zero.
In this case, the two symbols appearing on the display tube screen?
The intersection of is near the upper and lower ends of the starne upper frame. Obviously, the invention includes these modifications. Although the present invention has been described and illustrated in detail, each description is to be used by way of illustration only and not by way of limitation, and the spirit and scope of the invention lies within the scope of the following claims. Needless to say, it is limited only by the terminology.

[Brief explanation of the drawing]

1 is a block diagram of a jitter correction system according to the present invention, FIG. 2 is a block diagram of a jitter correction circuit provided in the embodiment of FIG. 1, and FIG. 3 is an operation of the embodiment of FIG. 2. An explanatory waveform diagram, FIG. 4 is a transfer characteristic diagram of the AFC of the horizontal oscillator provided in the monitor television receiver, FIG. 5 is a transfer characteristic diagram of the adjustment circuit provided in the embodiment of FIG. 1, and FIG. 7 and 7 are waveform diagrams of the pseudo composite video signal used in the present invention, and FIG. 8 is an observed view of the monitor television receiver Q display tube screen on which the pseudo composite video signal is displayed. Figure 9 shows
Circuit diagrams of several embodiments of the phase adjustment circuit provided in the adjustment circuit of the embodiment of FIG. 1, and FIG. 10 are corresponding transfer characteristic diagrams of each embodiment shown in FIG. Explanation of main drawing numbers, PSG...Pseudo composite video signal generator, VRA...Video playback device, JCC...Jitter correction circuit, TU...
・Monitor television receiver, 3...Horizontal synchronization signal phase modulation circuit, 13...Jitter detection circuit, 14...Amplitude and phase adjustment circuit, 8... ...
・AFC.

Claims (1)

[Claims] 1. A composite video signal of any television system, which comprises vertical and horizontal synchronization signals and a video signal, is reproduced from a recording medium, and the reproduced composite video signal is included in the composite video signal. A jitter correction method in a video playback device for supplying a monitor television receiver having an automatic frequency control AFC circuit for horizontal deflection in response to a played composite video signal, the method comprising: means for detecting a phase variation of a video signal caused by the AFC and an output from the AFC for causing jitter on the screen of the monitor television receiver in response to the phase variation detection output; compensation signal generating means for presenting a compensation signal for compensating for a phase difference between the regenerated composite video signal and, in response to said compensation signal, said regenerated composite video signal for presenting a phase modulated converted composite video signal of a horizontal synchronization signal; means for phase modulating a horizontal synchronization signal of a video signal; means for adjusting the amplitude and phase of the compensation signal provided in the compensation signal generation means; and means for adjusting the amplitude and phase of the compensation signal; a pseudo-composite video signal comprising a mark signal, wherein said horizontal synchronization signal of said pseudo-composite video signal is phase shifted compared to that of said television system, said pseudo-composite video signal comprising said reproduced composite video signal; a monitor is provided to the television receiver in place of a video signal, thereby allowing adjustment of the adjustment means while observing an indicia on the television receiver screen by the mark signal in the pseudo composite video signal; A jitter correction method for a video playback device, comprising: means for generating a pseudo composite video signal. 2. Jitter correction for a video playback device according to claim 1, wherein the horizontal synchronization signal in the pseudo composite video signal is composed of two types of horizontal synchronization signals, one of which is phase-advanced and the other is phase-lag. method. 3. The television system is an interlaced system, and is configured such that the leading-phase horizontal synchronizing signal included in one field and the lagging-phase horizontal synchronizing signal included in another field are arranged in field sequential format. A jitter correction method for a video playback device according to claim 2. 4. The video according to claim 3, wherein the field of the progressive horizontal synchronizing signal and the field of the delayed horizontal synchronizing signal are phase shifted with respect to the vertical synchronizing signal of the pseudo composite video signal. Jitter correction method for playback equipment. 5. A jitter correction method for a video playback device according to claim 1, wherein the means for generating the pseudo composite video signal is included in a recording medium on which the composite video signal is recorded for playback by the video playback device. . 6. The jitter correction method for a video reproducing apparatus according to claim 1, wherein said means for detecting a phase variation of said horizontal synchronizing signal of said reproduced composite video signal is a speed detection type detecting means. 7. The speed detection type detection means includes voltage controlled oscillation means and means for integrating the output from the voltage controlled oscillation means;
means for sampling the output from the integrating means with a horizontal synchronization signal of the reproduced composite video signal;
7. A jitter correction method for a video reproducing apparatus according to claim 6, further comprising means for holding the output from said sampling means to provide a reward output to said voltage controlled oscillation means. 8. The means for adjusting the amplitude and phase of the compensation signal includes means for adjusting the amplitude of the output from the means for detecting phase fluctuations of the reproduced composite video signal, and the means for adjusting the amplitude and phase of the reproduced composite video signal. 2. A jitter correction method for a video playback apparatus according to claim 1, further comprising means for adjusting the phase of the output from said means for detecting fluctuations. 9. The jitter correction method according to claim 8, wherein the phase adjustment means is a high-pass filter and a transfer characteristic changing means. 10 The transfer characteristic changing means includes a multistage step switch means, a plurality of capacitance means connected to each step of the multistage step switch means and having different capacitance values, and further a variable resistance means arranged in cooperation with the capacitance means. A jitter correction method for a video playback device according to claim 9, comprising: 11. The means for detecting phase variations in the horizontal synchronization signal of the reproduced composite video signal comprises means responsive to a trailing edge of the horizontal synchronization signal of the reproduced composite video signal. Jitter correction method for video playback device described in Section 1.