JPH05268560A - Method of preventing dubbing - Google Patents

Abstract

PURPOSE:To provide a method of generating a dubbing prevention signal by which illegal dubbing is effectively prevented without affecting a displayed video signal. CONSTITUTION:In this method of generating a dubbing prevention signal, a dubbing prevention signal DP whose level is higher than a maximum amplitude of a video signal and being pulses without any harmonic component is added to the video signal. Since the video signal recorder adjusts the amplitude of the video signal based on the dubbing prevention signal DP, the amplitude of the video signal is substantially compressed and the picture subject to dubbing is dark. Smear is less by adopting a pulse waveform without any harmonic component such as sinusoidal pulse waveform for the dubbing prevention signal DP.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dubbing prevention method for preventing illegal copying (copying or dubbing) and a video signal processing device used therefor.

[0002]

2. Description of the Related Art Conventionally, various dubbing prevention methods have been attempted for effectively preventing illegal dubbing in a video tape recording / reproducing apparatus or when providing a video signal. As such a dubbing prevention method,
It is desired to make dubbing substantially impossible by adding a certain signal to the soft tape without changing the hardware circuit of the video tape recording / reproducing apparatus. FIG. 12 is a conceptual diagram for preventing such dubbing. When recording from a soft tape to another video tape recording / reproducing device (VTR), the image quality of the image is blurred. The image quality of an image recorded on another VTR from the video tape recorded by is not deteriorated.

As a dubbing prevention method for the purpose of such image deterioration, a copy prevention method proposed by Macrovision (hereinafter referred to as macrovision method) is known (for example, Japanese Patent Laid-Open No. 63-107281). ,reference). The outline of the macrovision method is described below. As shown in FIG. 13, the macrovision method uses a normal automatic gain control (AGC) level LA during the blanking period.
Dubbing prevention signal DP for signals with excessive amplitude exceeding GC
Is applied as. The video tape recording / playback device is provided with an automatic gain adjustment (control) circuit, but when a signal exceeding the normal level is applied, the gain adjustment of the automatic gain adjustment circuit malfunctions, and as a result, the video signal is Amplitude is compressed to lower the original amplitude. Even when dubbing the amplitude-limited video signal, the reproduced image becomes dark and difficult to see, so that dubbing is meaningless and contributes effectively to the prevention of dubbing.

The amplitude limiting operation when an excessive amplitude signal is applied will be described with reference to the recording apparatus 200A or recording apparatus 200B shown in FIG. This recording device 20
0A is for performing the color difference line sequential processing of the high definition video signal, and does not effectively exhibit the dubbing prevention function for the dubbing prevention signal DP inserted in the blanking period in the macrovision method, but is based on the excessive amplitude. It is referred only to describe the amplitude limiting processing operation of the video signal. The recording apparatus 200 shown in FIG. 14A includes a low-pass filter block 20 and an automatic gain adjustment circuit block 2.
1, an A / D conversion circuit block 22, and a non-linear emphasis signal processing circuit 23. The non-linear emphasis signal processing circuit 23 includes a vertical filter circuit block 23A, a vertical non-linear emphasis circuit block 23B, and a horizontal non-linear circuit.
It is composed of an emphasis circuit block 23C.
The recording device 200A is also a TDM that performs color difference line sequential processing.
An encoding signal processing circuit 24, a signal adding circuit 25 for adding a synchronization signal SYNC and a burst signal BURST, a synchronization signal / burst signal generating circuit 26, a D / A conversion circuit block 27, a low pass filter block 28, an emphasis circuit block 29, and It has an FM modulation circuit block 30. The video signal subjected to the color difference line sequential processing is recorded on the video tape 10 via the magnetic heads 31A and 31B. Recording device 200B shown in FIG.
Is the TD of the horizontal non-linear emphasis circuit block 23C of the recording device 200A illustrated in FIG.
The M-encoded signal processing circuit 24 is moved to the subsequent stage.

Consider the automatic gain adjustment circuit block 21 shown in FIG. Automatic gain adjustment includes synchronous gain adjustment (AGC) and peak AGC. The baseband signal of the high definition video signal includes the luminance signal Y, the first color difference signal P _B and the second color difference signal P _R, but it is not necessary to apply the synchronization AGC and the peak AGC to all the video signals. ， It is disadvantageous in terms of price to apply all AGC. As a result, as shown in FIG. 15, the automatic gain adjustment (AGC) circuit 21A for the luminance signal is synchronized with the synchronization A
The GC circuit 21A1 and the peak AGC circuit 21A2 are configured, and as shown in FIG. 16, the automatic gain adjustment circuits 21B and 21C for the color difference signals of the first color difference signal P _B or the second color difference signal P _R are synchronized. It is configured as an AGC circuit only. The reason will be considered with reference to FIGS. 17 and 18.

FIG. 17A is a signal waveform diagram for explaining the operation of the synchronous AGC, and FIG. 17B is a signal waveform for explaining the operation of the peak AGC. FIG. 18A shows a waveform when the negative (lower) amplitude of the ternary horizontal synchronizing signal H-SYNC added to the luminance signal Y loses only the level La, and FIG. 18B shows the first waveform. 7 shows a waveform when the negative (lower side) amplitude of the ternary horizontal synchronizing signal H-SYNC added to the color difference signal P _B is lost by the level Lb. As the AGC in the video tape recording apparatus, as shown in FIG. 17A, the difference between the negative polarity level of the horizontal synchronizing signal H-SYNC and the pedestal level immediately after it, the synchronous AGC that keeps L1 constant, and FIG. As shown in B), the horizontal synchronization signal H
There is a peak video signal that keeps the level difference L2 between the negative level of SYNC and the peak of the video signal constant. If the signal level abnormality caused by the influence of the transmission system is a linear change with respect to the original signal, the luminance signal Y, the first color difference signal P _B , the second
The original signal should be reproducible only by the function of the synchronous AGC for both the color difference signals P _R. However, when the deformation is non-linear, the situation is different if the signal information is lost below a certain level.

Regarding the luminance signal Y, as shown in FIG. 18A, the negative level of the horizontal synchronizing signal H-SYNC is L.
Even if only a is lost, there is no signal component below the pedestal level, so the peak-peak value of the signal itself is not affected. Therefore, the synchronous AGC circuit 2 shown in FIG.
When 1A1 is passed, the signal level becomes higher than the normal level, and there is a risk of causing a “whiteout phenomenon”. Therefore, the peak AGC circuit 21A2 further requires a peak AGC that keeps the peak value of the signal within a specified value. Regarding the first color difference signal P _B and the second color difference signal P _R , the negative polarity level of the horizontal synchronization signal H-SYNC is Lb.
When it is lost, the peak-to-peak value of the signal itself also decreases. Therefore, the peak-to-peak value of the output signal of the synchronous AGC circuit 21B or 21C shown in FIG. 16 becomes a normal value, and therefore the synchronous AGC is sufficient and the peak AGC circuit is not necessary. An excessive amplitude signal in the above macrovision system intentionally causes such an automatic gain adjustment circuit to malfunction, and the video signal that arrives afterwards is displayed with the amplitude limited to the excessive amplitude signal. It makes a dark image and deteriorates the image quality.

[0008]

In the macrovision method described above, an excessive amplitude signal is applied within a blanking period so as not to affect a normal video signal. Therefore, the macrovision method is premised on that the excessive amplitude signal is used as it is, without being removed in the video tape recording / reproducing apparatus. Therefore,
The problem that the macrovision method cannot be applied to the video tape recording / reproducing apparatus of the method that performs the signal processing of the color difference line sequential method on the input video signal without removing the applied signal during the blanking period and using I have encountered. 14
The recording device 200A or the recording device 200B shown in FIG.
Color difference line sequential processing is performed in the TDM encode signal processing circuit 24 without using the signal in the blanking period, and the necessary synchronization signal SYN is generated from the synchronization signal / burst signal generation circuit 26.
Since C and burst signal BURST etc. are added,
The macrovision method is invalid in the recording apparatus 200 of this method. Therefore, as described above, FIG.
The recording devices 200 and 200B described above merely serve as a reference for describing a malfunction of automatic gain adjustment when an excessive amplitude signal is applied.

A specific example of the above-mentioned video signal processing of the color difference line sequential system is shown in FIG.
This will be described with reference to the processed waveform of the video signal shown in FIG. Figure 1
Reference numeral 9 shows a waveform of a high-definition video signal which is signal-processed in the recording device 200A. FIG. 19A shows a high-definition video signal input to the recording device 200A.
For each 1H, the luminance signal Y, the first color difference signal P _B , and the second color difference signal P are successively added to the three-valued horizontal synchronizing signal H-SYNC.
It is a figure which shows the waveform of _R. FIG. 19B shows the recording device 2
00, the ternary horizontal synchronizing signal H-SYNC in the blanking period is not used, and the luminance signal Y, the first color difference signal P _B, and the second color difference signal P _R are time-divided in the TDM encode signal processing circuit 24. The signal form is shown in which the signal is converted into an axial compression / expansion (TCI) signal and further arranged in color difference line order to form an A channel signal Ach and a B channel signal Bch. In FIG. 19C, a ternary horizontal synchronizing signal H-SYNC, a burst signal BURST, etc. are added to the color difference line sequential signal in the recording device 200, and FM modulation is performed in the FM modulation circuit block 30 to magnetic heads 31A, 31B. The signal waveforms of the A and B channels that are actually recorded on the video tape through are shown. The horizontal synchronizing signal H-SY shown in FIG.
NC, burst signal BURST, etc. are added in the video tape recorder. At the stage shown in FIG. 19 (A), even if an excessive amplitude signal by the macrovision method is applied within the blanking period (blanking), FIG. 19 (B)
Since the signal within the blanking period is not used at the stage of processing to the signal shown in (1), the application of an excessive amplitude signal by the macrovision method for the purpose of preventing dubbing is meaningless.

Even when the color difference line sequential method is not used, the dubbing prevention signal DP of the macrovision method is used.
The problem arises when adding. FIG. 20 shows a plan view of the display screen of the high-definition TV monitor screen 11. The high-definition TV monitor screen 11 is provided with an effective image display area 11A at the center, an overscan area 11B around it, and a spare area 11C around it. It is assumed that the dubbing prevention signal DP shown in FIG. 21 is applied to the lines 1 to 5 in the overscan area 11B in which the video signal is not effectively displayed. If the dubbing prevention signal DP has a harmonic rectangular waveform, overmodulation and waveform distortion are likely to occur in the recording device 200A. In particular, vertical non-linear
By the filtering processing in the emphasis circuit block 23B and the horizontal non-linear emphasis circuit block 23C, the overmodulation and the waveform distortion are increased, and the large waveform distortion shown by the shaded area in FIG. The smearing phenomenon occurs, and the image deteriorates. Figure 2
2 shows the number of lines on the horizontal axis and the waveform distortion in the vertical direction on the vertical axis, which indicates that the waveform distortion enters the effective image display area 11A and causes the smear phenomenon. In other words, even if the dubbing prevention signal is added,
Although it is an effective dubbing prevention measure to cause abnormal image quality deterioration only when dubbing without causing image quality deterioration on the TV monitor, the above-mentioned example has a problem of causing deterioration in display image quality.

From the above consideration, the present invention does not cause the image quality deterioration of the display image, and is applicable to the dubbing prevention method applicable to the video signal processing apparatus for performing the signal processing of the color difference line sequential method. An object is to provide a video signal processing device.

[0012]

In order to solve the above problems, according to the present invention, a dubbing prevention signal having a pulse waveform having an amplitude larger than the maximum amplitude of a video signal and containing no harmonic component is used as the video signal. A method for preventing dubbing is provided. Specifically, the dubbing prevention signal is inserted into a video signal storage position outside the area where the video signal is effectively displayed, or the dubbing prevention signal is inserted into the blanking period. Preferably, the anti-dubbing signal that does not include the harmonic component is a sine-wave pulse signal or a cosine-wave pulse signal. Regarding the timing of adding the dubbing prevention signal, it is added at the time of generating the video signal or at the time of reproducing the video signal. Further, preferably, the amplitude of the dubbing prevention signal is changed with time.

[0013]

When the dubbing prevention signal has a pulse waveform that does not include harmonic components, waveform distortion is less likely to occur even with a filter used in the emphasis processing of the recording apparatus. Therefore, even if such a dubbing prevention signal is added, an image smear is generated. The image quality does not deteriorate due to the phenomenon. A sine wave or cosine wave waveform is preferable as the pulse waveform that does not include harmonic components. Effectively TV at the video signal storage position
If a dubbing prevention signal is inserted at a position not displayed on the monitor, for example, in an overscan area or a spare area in a high-definition TV, it will be subject to automatic gain control and dubbing prevention will be possible even in the color difference line sequential method. The timing of adding the dubbing prevention signal may be at the time of generating the video signal or at the time of reproducing the video signal. Further, if the amplitude of the dubbing prevention signal is changed with time, it is possible to intentionally cause the automatic gain adjustment circuit in the recording device to malfunction to record a color-difference signal having meaningless amplitude changes, and it is meaningless to reproduce it. It becomes an image and can prevent dubbing.

[0014]

1 is a block diagram of a dubbing prevention apparatus as a first embodiment for realizing the dubbing prevention method of the present invention. As an embodiment of the present invention, an example applied to a high-definition video tape recording / reproducing apparatus will be described below. The dubbing prevention device shown in FIG. 1 is a video signal generation device 1, a dubbing prevention signal addition device 3, a video tape 5 as an example of a video signal recording medium, and a video signal recording / reproducing device (or a video signal processing device for high definition). Device) 7
Have.

FIG. 2 shows a video signal having the waveform of the dubbing prevention signal DP as the first embodiment of the present invention. Figure 2
The dubbing prevention signal DP is a pulse signal containing no harmonic component, and its amplitude exceeds the maximum amplitude of the video signal, for example, the luminance signal Y. The dubbing prevention signal DP is a sine wave pulse, a cosine wave pulse, or a pulse represented by (sine wave pulse) ² , as shown in the enlarged view of FIG. Below, an example using a sinusoidal pulse is described.
In the dubbing prevention signal adding device 3, such a dubbing prevention signal DP is added to the original luminance signal Y, the first color difference signal P _B and the second color difference signal P _R.

The dubbing prevention signal DP shown in FIG. 3 is shown in FIG.
An example in which the voltage is applied to the position of the overscan area 11B of the high-definition TV monitor screen 11 shown in FIG. The dubbing prevention signal DP of line 2 is ahead of the dubbing prevention signal DP of line 1 by time t1, and the dubbing prevention signal DP of line 3 is further advanced.
It is ahead of P by time t2. In this way, the addition timing of the dubbing prevention signal DP is shifted because the effective image display area 11 of the high-definition TV monitor screen 11 is shifted.
This is to minimize duplication of the smear phenomenon in A. The high-definition TV monitor screen 11 includes an effective image display area 11A, an overscan area 11B, and a spare area 1.
With 1C. FIG. 5 shows a high-definition TV monitor screen 1 when the dubbing prevention signal DP shown in FIG. 3 is applied.
3 shows signal waveforms at the horizontal scanning line direction position H1, vertical scanning line direction positions V1 and V2 in FIG. By using the sinusoidal pulse as the dubbing prevention signal DP, the waveform distortion as shown by the diagonal line is conventionally generated, but according to the present embodiment, the waveform distortion is slight as shown by the solid line, which causes a problem. No significant smear phenomenon occurs in the effective image display area 11A.

FIG. 6 shows the waveform of the dubbing prevention signal DP of the second embodiment according to the dubbing prevention method of the present invention. This dubbing prevention signal DP changes the amplitude of the dubbing prevention signal DP in the dubbing prevention signal adding device 3 with the passage of time. As illustrated in FIGS. 15 and 16, since the AGC of the color difference signal is the peak AGC, when the amplitude of the dubbing prevention signal DP changes, in the automatic gain adjustment circuit 21A, 21B or 21C in the automatic gain adjustment circuit block 21, As shown in FIG. 7, the video tape 10 is produced by intentionally changing the amplitude of the original signal component of the video signal.
To record. When the video tape 10 on which the video signal whose amplitude has been changed is recorded is loaded in the video signal reproducing device and the recorded video signal is reproduced and displayed on the high-definition TV monitor screen 11, the amplitude of the luminance signal is changed. The image changes drastically with time and becomes irrelevant for viewing, and it is not worth dubbing, thus contributing to the prevention of dubbing.

It is preferable to randomly change the amplitude of the dubbing prevention signal DP as described above.
For example, the time constant of the automatic gain adjustment circuit in the recording device 200, which will be described later, may be changed at a time interval that causes hunting. Although the luminance signal Y is illustrated as the video signal illustrated in FIGS. 6 and 7, the dubbing prevention signal DP
May be added to the first color difference signal P _B, the second color difference signal P _R , or both color difference signals. Further, the dubbing prevention signal DP may be added to both the luminance signal Y and the color difference signal C.

FIG. 8 shows the waveform of the dubbing prevention signal DP of the third embodiment of the dubbing prevention method of the present invention. The dubbing prevention signal DP is inserted in the blanking period in the dubbing prevention signal adding device 3. 14
Although the processing of the dubbing prevention signal DP cannot be directly used in the recording apparatus 200A that performs the color difference line sequential processing shown in (1), it can be applied to the recording apparatus that performs normal signal processing. Since the waveform of the dubbing prevention signal DP is also a sine wave pulse, when inserted in the blanking period, no waveform distortion is caused in the effective display area.

FIG. 9 shows the dubbing prevention signal DP shown in FIG.
The waveform diagram as a modification of FIG. The dubbing prevention signal DP shown in FIG. 9 is a signal in which two sine wave pulses are continuous. Such two consecutive dubbing prevention signals DP
Similarly to the above, the addition of “” effectively functions as a dubbing prevention signal.

Another method of adding the dubbing prevention signal DP to the video signal will be described. In the above-described embodiment, the dubbing prevention signal DP is added immediately after the video signal is generated as shown in FIG. 1, but the dubbing prevention signal DP can be added at the reproduction stage in the video signal reproducing apparatus. Whether or not to perform such processing is performed using a video signal storage portion other than the area in which the effective display video signal of the high-definition video signal is stored. FIG. 12 shows a recording format of a high-definition video signal recorded on the video tape 10. This video signal recording format indicates that the video signals arranged in the color difference line sequence are stored in the preampule PRE AMBLE. Although a maximum of, for example, 1125 lines is prepared as a high-definition video signal, the effective video display area 11A shown in FIG.
The number of lines is 035, and a line for the overscan area 11B of about several percent is prepared around the line. Further, there is a spare storage area corresponding to the spare area 11C. In this example, the spare storage area starts from the 17th for the first field and the 5th for the second field.
It starts from the 79th. The overscan area is the first
The fields start from the 41st position, and the second fields start from the 603rd position.

Even if a video signal is inserted in the overscan area preliminary storage area, it is not displayed in the effective video display area 11A of the high-definition TV monitor screen 11. Therefore, the pattern data indicating the dubbing prevention signal is stored in these areas, the dubbing prevention signal is detected in the reproducing stage, and the dubbing preventing signal DP is added in the reproducing stage as described above. The circuit configuration will be described with reference to FIG. A reproducing apparatus 400 illustrated in FIG. 11 includes magnetic heads 31A and 31B for detecting a video recording signal of a color difference line sequential system from a video tape 10, an FM demodulation circuit block 41,
It has a de-emphasis circuit block 42, a low-pass filter block 43, and an A / D conversion circuit block 44. The reproducing apparatus 400 also returns the color difference line sequential signal to the components of the luminance signal Y, the recording color difference signal PB and the second color difference signal P _R , the TDM / deshuffling processing circuit 45, the horizontal non-linear de-emphasis circuit block 46, the vertical non-linear circuit. -De-emphasis circuit block 47, vertical filter circuit block 48, D / A conversion circuit block 49, signal addition circuit block 50, low-pass filter block 5
2, a sync signal / burst signal generation circuit 53 for color difference signals,
It has a luminance signal sync signal / burst signal generation circuit 54 and a dubbing prohibition signal detection circuit 55.

First, in the dubbing prevention signal adding device 3 shown in FIG. 1, the overscan area 11 shown in FIG.
Data of a signal pattern that cannot exist in nature is recorded at the position corresponding to B at the video signal storage position shown in FIG. 10 or at the position corresponding to the preliminary storage area. An example of the data pattern is shown below. Table-1 Blue = + 50% and Red = + 50% or Blue = + 50% and Red = −50% or Blue = −50% and Red = + 50% or Blue = − 50% and red = -50%

When the dubbing prohibition signal detection circuit 55 detects the video signal of the data pattern, it drives the color difference signal sync signal / burst signal generation circuit 53. In response to the detection of the data pattern, the color difference signal sync signal / burst signal generation circuit 53 applies the dubbing prevention signal DP to the luminance signal Y signal addition circuit 50A as shown in FIG. Of course, the dubbing prohibition signal detection circuit 55 drives the color difference signal synchronization signal / burst signal generation circuit 53, and like the luminance signal synchronization signal / burst signal generation circuit 54,
The dubbing prevention signal DP may be added to the first color difference signal P _B and the second color difference signal P _R. An example in which the dubbing prevention signal DP is added only to the luminance signal Y will be described below.

When the dubbing prevention signal DP is added to the luminance signal Y, the reproduction signal added with the dubbing prevention signal DP is recorded, for example, in the recording device 20 shown in FIG.
When dubbing at 0A and 200B, the amplitude of the luminance signal Y is limited and recorded on the video tape 10. Even if the video tape 10 is further reproduced and displayed on the high-definition TV monitor screen 11, as described above, it becomes a poor image that cannot be viewed because it is dark.

The addition of the dubbing prevention signal DP in the luminance signal synchronizing signal / burst signal generating circuit 54 may change the amplitude over time as shown in FIG.
The effect of the dubbing prevention signal DP at that time is the same as that described above. The reproduced image becomes a fickle and inferior image.

Instead of inserting the data pattern indicating the prohibition of dubbing into the video signal storage area described above, the data indicating the prohibition of dubbing is recorded in the index signal ID storage portion of the preampule PRE AMBLE shown in FIG. Good. The dubbing prohibition signal detection circuit 55 detects the dubbing prohibition signal from the index signal storage portion and drives the dubbing prohibition signal detection circuit 55 or the color-difference signal synchronization signal / burst signal generation circuit 53 in the same manner as described above to dubb the video signal. The prevention signal DP is added.

As described above, the embodiments of the present invention have been mainly described in relation to the high-definition video signal, but the present invention is not limited to the processing of the high-definition video signal, but the video signal at the timing. It can be applied to prevent dubbing. Further, in the above-mentioned example, a case where the horizontal synchronizing signal H-SYNC is a three-valued horizontal synchronizing signal and the video signal is the luminance signal Y, the first color difference signal P _B and the second color difference signal P _R is illustrated. However, the video signal of the present invention is not limited to such a video signal configuration.

[0029]

As described above, according to the present invention, dubbing can be effectively prohibited without affecting the displayed video signal.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a dubbing prevention device applied to a dubbing prevention method of the present invention.

FIG. 2 is a diagram showing a waveform of a dubbing prevention signal of the first embodiment added by the dubbing prevention signal adding device in FIG.

FIG. 3 is a waveform diagram showing a modified example of the dubbing prevention signal shown in FIG.

FIG. 4 is a TV on which the dubbing prevention signal shown in FIG. 3 is displayed.
It is a structure of a monitor screen and its front view.

5 is a display waveform diagram of a video signal on the TV monitor screen shown in FIG.

FIG. 6 is a diagram showing a waveform of a dubbing prevention signal of the second embodiment added by the dubbing prevention signal adding device in FIG. 1;

7 is a waveform diagram of a video signal whose peak gain is adjusted based on the dubbing prevention signal shown in FIG.

8 is a diagram showing a waveform of a dubbing prevention signal of the third embodiment added by the dubbing prevention signal adding device in FIG.

9 is a diagram showing a waveform of a dubbing prevention signal of a fourth embodiment added by the dubbing prevention signal adding device in FIG.

FIG. 10 is a format diagram of a high-definition video signal applied to the dubbing prevention method of the present invention.

FIG. 11 is a diagram showing a device configuration for generating a dubbing prevention signal in a video signal reproducing device as a second embodiment of the dubbing prevention method of the present invention.

FIG. 12 is a diagram showing a general concept for preventing dubbing.

FIG. 13 is a diagram showing a waveform of a conventional dubbing prevention signal.

FIG. 14 is a configuration diagram of a video signal recording device applied to the dubbing prevention method of the present invention.

FIG. 15 is an automatic gain adjustment circuit diagram for a luminance signal in the video signal recording device shown in FIG.

16 is an automatic gain adjustment circuit diagram for color difference signals in the video signal recording device shown in FIG.

17 is an operation of the synchronous AGC shown in FIG. 15 and FIG.
7 is a signal waveform diagram showing the operation of the peak AGC shown in FIG.

18 is a synchronous AGC in the AGC circuit shown in FIG.
FIG. 3 is a signal waveform diagram for explaining the operation of 1 and the operation of peak AGC.

FIG. 19 is a waveform diagram for wetting the color difference line sequential signal processing in the video signal recording device shown in FIG.

FIG. 20 is a diagram showing a display example of a video signal on a TV monitor screen.

FIG. 21 is a signal waveform diagram when a conventional dubbing prevention signal is displayed.

22 is an analysis diagram of the signal waveforms shown in FIG. 21. FIG.

[Explanation of symbols]

1 ... Video signal generator, 3 ... Dubbing prevention signal adding device, 5 ... Video tape, 7 ... Video signal processing device (video signal recording / reproducing device), 10 ... Video tape, 11 ... For high-definition TV monitor screen, 11A ... Effective video display area, 11B ... Overscan area, 11C ... Reserve area, 20 ... Low pass filter block, 21 ... Automatic gain adjustment circuit block, 22 ... A / D conversion circuit block , 23 ··· Non-linear emphasis signal processing circuit, 23A · · Vertical filter circuit block, 23B · · Vertical non-linear emphasis circuit block, 23C · · · Horizontal non-linear emphasis circuit block, 24 · · TDM encode signal processing circuit , ··· Signal adder circuit, 26 ··· Sync signal, burst signal Raw circuit, 27 ... D / A conversion circuit block, 28 ... Low-pass filter block, 29 ... Emphasis circuit block, 30 ... FM modulation circuit block, 31A, 31B ... Magnetic head, 41 ... FM demodulation circuit block , 42 ... De-emphasis circuit block, 43 ... Low-pass filter block, 44 ... A / D conversion circuit block, 45 ... TDM deshuffling processing circuit, 46 ... Horizontal non-linear de-emphasis circuit block, 47 ... Vertical Non-linear de-emphasis circuit block, 48 ... Vertical filter circuit block, 49 ... D / A conversion circuit block, 50 ... Signal addition circuit block, 51 ... Sync signal / burst signal generation circuit, 52 ... Low pass filter block .., sync signal for color difference signal, burst signal Generating circuit, 54 ... luminance signal sync signal burst signal generating circuit, 55 ... dubbing prohibition signal detecting circuit, 200 ... recording device, 400 ... playback device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuka Oikawa 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (7)

[Claims] 1. A dubbing prevention method for adding a dubbing prevention signal having a pulse waveform having an amplitude larger than the maximum amplitude of a video signal and having no harmonic component to the video signal. 2. The dubbing prevention method according to claim 1, wherein the dubbing prevention signal is inserted into a video signal storage position outside an area where the video signal is effectively displayed. 3. The dubbing prevention method according to claim 1, wherein the dubbing prevention signal is inserted in a blanking period. 4. The dubbing prevention method according to claim 2, wherein the dubbing prevention signal having no higher harmonic wave component is a sine wave pulse signal or a cosine wave pulse signal. 5. The dubbing prevention method according to claim 1, wherein the dubbing prevention signal is added at the time of generating a video signal. 6. The dubbing prevention method according to claim 1, wherein the dubbing prevention signal is added at the time of reproducing a video signal. 7. The dubbing prevention method according to claim 1, wherein the amplitude of the dubbing prevention signal is changed with time.