JP2542905B2 - Duplicate-prerecorded video tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention Industrial Field With the spread of video tape recorders (hereinafter referred to as VTRs), prerecorded video tapes (hereinafter referred to as soft tapes) containing movies and the like are becoming popular. However, 2
If you use a VTR on a stand, you can easily copy (dubb) the soft tape.

It is permitted to record television broadcast signals and use them for personal purposes, but it is legally prohibited to copy copyrighted softtapes.

However, when such illegal acts are carried out on a small scale in ordinary households, it is difficult to detect them due to legal operation technology, which causes software vendors to hesitate to record and market excellent works. ing.

The present invention relates to an anti-duplication recorded video tape which can prevent illegal duplication and use of an image recorded on a video tape.

2. Description of the Related Art An image screen of a television broadcast adopted in Japan and the United States is composed of 525 horizontal scanning lines, and interlaced scanning is performed by skipping every other line to reduce flicker. That is, odd-numbered scans indicated by solid lines 1, 3, 5, ... In FIG. 5 are performed, then even-numbered scans indicated by dotted lines 2, 4, 6, ... The video will be completed. Scanning with an odd number or even number is called field scanning, and a combination of both, that is, two field scannings is called frame scanning.

625 scan lines in most of Europe and 405 in the UK
Books, 819 are used in France, but interlaced scanning is performed in all, 30 frames per second in Japan and the United States,
In Europe, 25 frames of video are sent every second.

The television signal includes a video signal, a blanking signal, a composite synchronizing signal, and the like.

The composite sync signal is also simply called a sync signal and is a composite signal composed of a horizontal sync pulse, a vertical sync pulse and an equalization pulse, and is used to control the phase of deflection of the scanning beam of the receiver, that is, each horizontal sync pulse is a horizontal sync pulse. The beginning of the scan line is at the left edge of the screen, and the vertical sync pulse is used to control the beginning of each field to be at the upper left corner of the screen.

FIG. 6A is a waveform diagram in the vicinity of the sync signal in the first field of the interlaced scanning, showing 3H (1H is 1H in the vertical blanking interval E between the end F of one field image and the beginning G of the next field image). Equalized signal section A, which corresponds to 63.5 μsec in the time from the beginning of one scan line to the beginning of the next scan line),
Vertical sync signal section B of 3H, equalization signal section C of 3H and 12H
The horizontal synchronizing signal section D is sequentially provided. The horizontal synchronizing pulse T is provided not only in the horizontal synchronizing pulse section but also for each video scanning signal. Although there are 6 pulses in the vertical sync signal section, they are extracted as one rectangular pulse by the vertical sync signal separation circuit of the television receiver. In FIG. 6A, the symbol K is a video signal section, the symbol L is a horizontal blanking interval, the symbol M is a black level, the symbol N is a white level, the symbol P is a pedestal level (base of the synchronizing signal), and the symbol Q is a video signal. Indicates the maximum carrier voltage.

FIG. 6B is a waveform diagram in the vicinity of the sync signal in the next field of the interlaced scanning, which is similar to FIG. 6A except that there is a 0.5H time lag.

On the other hand, the VTR records such a television signal on a magnetic tape and reproduces the television signal from the recorded magnetic tape.

In a helical scanning rotary two-head system VTR which is now widely used, a rotary drum (head) provided with two video heads 1A and 1B is shown in a plan view of FIG. 7 and a perspective view of FIG. (Cylinder) 2 is arranged diagonally with respect to the tape 3, and when the tape 3 is run at a low speed with the tape wound around more than half the circumference and the drum 2 is rotated in the tape running direction (30 rotations / second), the tape Two video heads will alternately run diagonally on the surface. Symbol 4 is a cassette, symbol 41 is a supply reel, symbol
42 is a take-up reel, symbol 5 is a tape guide, symbol 2 '
Is a fixed portion at the bottom of the drum, and symbol 6 indicates the rotating direction of the drum.

When recording a television signal, oblique video tracks 31A, 31B, ... Are formed on the surface of the tape 3 as shown in FIG. One track corresponds to one field,
31A is recording by the head 1A shown in FIG. 7, and track 31B is recording by the head 1B shown in FIG. 7. The signal waveform in the first field of the interlaced scanning shown in FIG. The signal waveforms in the next field of the interlaced scan showing the part are alternately recorded. Symbol 32 is the tape running direction,
Symbol 33 is the direction of rotation of the video head, symbol 44 is the audio track, and symbol 35 is the control track. The vertical sync signal is recorded at the position of symbol 36.

The VTR uses a motor to rotate the video head and run the tape.

The unevenness of the rotation of the video head causes the screen to fluctuate and the screen to be disturbed. The unevenness of the rotation of the capstan that runs the tape appears on the playback screen as a phenomenon that the screen fluctuates and the track of the playback video head deviates from the recording track. A servo is required to prevent these phenomena, and a circuit that controls the rotation speed and phase of the motor with a feedback loop that includes the motor is called a servo circuit.

 FIG. 11 shows a schematic configuration of a typical servo circuit.

When recording the television signal, the television signal 10
Vertical sync signal separated from 1 and divided by 1/2 to generate 3
A control pulse 103 of 0 Hz indicates the rotational position of the video head attached to the rotary part of the rotary video head.
The phase of the PG pulse from the PG (pulse generator) 104 is compared 105 to correct the deviation of the rotational phase of the video head 2, and the frequency 107 of the FG (frequency generator) 106 attached to the rotary video head shaft is used. The speed is detected 108 to correct the deviation of the rotation speed of the drum motor 109 that rotates the video head. Reference numeral 110 is a drive amplifier of the drum motor.

Further, when the tape 3 runs, the speed 113 is detected from the frequency 112 of the FG mounted on the capstan shaft 111 to correct the deviation of the rotational speed of the capstan motor 114, and the phase comparison 115 with the control pulse 103 is performed to measure the tape speed. The gap is corrected. Reference numeral 116 is a drive amplifier of the capstan motor.

On the other hand, the control pulse 103 is sent to the control head 117.
Is recorded on the control track at the end of the tape 3 via the.

The control pulse is recorded on the control track 35 at the end of the tape 3 as shown in FIG.

For reproduction servo when reproducing a television signal recorded in this manner, a capstan servo system is used for tracking. This is a method to control the rotation phase of the capstan, switch the changeover switches 120 and 121 to the playback side, and
This is a method in which the phase of 103 is synchronized with a reference signal generated by dividing (123) the crystal oscillator 122 to match the recording track and the tracking of the rotary video head. In this method, since the rotating drum is rotated at a constant speed, screen shake (jitter) during reproduction is reduced. It is also advantageous in performing variable speed reproduction and is widely used.

In order to prevent illegal duplication of soft tape, when dubbing with two commercially available VTRs, make sure that the control signal is not stored in the dubbed tape or the synchronization circuit of the television receiver. A method has been proposed in which a pseudo sync signal is inserted or a part of the sync signal is extracted so that the sync signal for activating is not copied.

Japanese Unexamined Patent Publication No. 51-146113 (U.S. Patent No. 3963865, British Patent No. 1
537283), there is a method of preventing the control signal from being recorded on a duplicated video tape which is duplicated based on this video tape, by making the vertical sync pulse one and a half and erasing or moving the remaining vertical sync pulse. Proposed.

Here, the vertical sync pulse is said to be one and a half,
One and a half of the six pulses in the vertical sync signal section B shown in FIG. 6A are indicated, but whether the number of pulses is six or one and a half in the vertical sync signal separation circuit of the television receiver, Since a rectangular pulse is also extracted as one rectangular pulse, the method of the above-mentioned Japanese Patent Laid-Open No. 51-146113 uses the vertical synchronizing pulse separated by the vertical synchronizing signal circuit for about 48 μsec (3H × 1.
5/6 = 0.75H).

Further, Japanese Patent Laid-Open No. 52-130314 discloses a video tape recorded by a VTR of a helical scanning Ω type rotating two-head system, in which a vertical synchronizing signal is recorded on a video track of the video tape in a weakened state. There has been proposed a copy-prevention video tape in which a reproduction control signal is not recorded on a duplicate video tape duplicated based on the video tape. The "state in which the vertical synchronizing signal is weakened" in Japanese Patent Laid-Open No. 52-130314 refers to a state in which the vertical synchronizing signal is weakened based on one rectangular pulse having a width of about 3H, which is separated by the vertical synchronizing signal circuit. In FIG. 2 of the publication, it is suggested that the width should be about half, that is, about 96 μsec (1.5H) or the height should be half.

All of these are intended to make normal playback by VTR impossible if dubbing is done by modifying the vertical sync signal and allowing playback by VTR as it is.

The above-mentioned means are used in the Showa period when these inventions were applied.
The current VTR whose technical level has improved, even if it is effective against the VTR technical level of 50-51 or the VTR of a specific method
However, when the present inventor tested using a VTR that is currently on the market, it was possible to obtain a normal image with a dubbed tape with this degree of copy protection.

Japanese Laid-Open Patent Publication No. 54-108612 discloses a horizontal sync signal portion of a television signal to be recorded or its back, so that the AGC circuit (automatic gain control circuit) of the VTR malfunctions so that a practical image cannot be recorded. A method of preventing duplication of a recorded video tape in which a pulse corresponding to approximately 100% white level is superimposed and recorded on a part of the pouch is described, but this method may or may not be effective.

The prior art has been described above with reference to some specific examples.
It is clear that none of these have universal effects on all commercially available VTRs, as they are not currently addressed as effective counter-measures against illegal dubbing.

The present inventor has disclosed in Japanese Patent Application No. 62-187683 that the width of the vertical sync pulse separated by the vertical sync signal separation circuit is 1 to
A composite video signal is recorded on at least part of the tape for 20 μs, and all equalization pulses after the vertical sync pulse and at least part of the horizontal sync pulse in the vertical blanking interval are below the pedestal level. We have proposed a video tape that has been recorded with anti-duplication.

FIG. 4 shows a waveform diagram in the vicinity of the synchronizing signal of the composite video signal in Japanese Patent Application No. 62-187683, which corresponds to FIG. 6A showing a standard television signal waveform.

In comparison with FIG. 6A, the six equalizations in the first equalized signal section A in the vertical blanking section E between the end F of one field picture and the beginning G of the next field picture. The pulse remains unchanged, but the vertical sync signal section B
There is only a pulse B1A having a width corresponding to 1 to 20 μs as a vertical synchronization pulse that can be separated by the vertical synchronization signal separation circuit. Here, "separated by the vertical synchronizing signal separation circuit" is represented on the waveform diagram as having a height sufficiently higher than the pedestal level P, and B2 to B6 in FIG. 4 are pulsed. Also pedestal level P
Since it is as follows, it is not separated as a vertical sync pulse by a vertical sync signal separation circuit such as a television receiver.

That is, the vertical sync pulse that can be separated by the vertical sync signal separation circuit has only a pulse B1A having a width of 1 to 20 μs, and there is no other vertical sync pulse, or the pedestal level P or less as shown in FIG. And all the equalizing pulses in the equalizing signal section C after the vertical synchronizing pulse and the horizontal synchronizing signal section D in the vertical blanking section E.
At least a part of the horizontal synchronizing pulse T (in the example of the figure,
9 out of 12 horizontal sync pulses except the last 3)
Is below the pedestal level P.

At least a part of all the equalized pulses in the equalized signal section C after the vertical synchronizing pulse and the horizontal sync pulse T in the horizontal sync signal section D in the vertical blanking interval E is set to the pedestal level P or lower. This is because if there is a pulse of pedestal level P or higher in this section, it may be picked up as a vertical synchronizing pulse.

The vertical sync pulse having a width of 1 to 20 μ does not necessarily have to be at the head of the vertical sync signal section B.

FIG. 10 shows a model of a track of a video tape on which the composite video signal having the waveform shown in FIG. 4 is recorded.
The vertical sync signal 36 is recorded with a much smaller width than in the case of FIG. 9 showing a conventional recording track.

In this way, the recorded video tape in which only the pulse of the width of 1 to 20 μs is recorded as the vertical synchronization pulse that can be separated by the vertical synchronization signal separation circuit, when it is directly reproduced by the VTR, A clear image can be reproduced without any problem, but if the dubbing is illegally performed using two VTRs, the rectangular wave is a vertical synchronizing pulse B1A with a width of 1 to 20 μs, and the rectangular wave has electrical resistance of the cable connecting the two VTRs. The signal, which has been integrated by the floating capacitance and has a low peak and a sharp rising edge on the front surface, will be recorded on the dubbed tape and will no longer function as a vertical synchronizing signal. As a result, even if the illegally dubbed tape is reproduced, the image is disturbed and completely meaningless flow lines appear on the TV screen.

However, although such a copy protection recorded video tape can prevent illegal dubbing with a widely used household VTR popular product, a professional trader
It was found that it is difficult to prevent illegal dubbing by using Base Corrector (TBC) together or to prevent illegal dubbing by using high-grade home VCR with TBC.

Problems to be Solved by the Invention The present invention is a further improvement of the invention disclosed in Japanese Patent Application No. 62-187683 (Japanese Patent Application Laid-Open No. 64-32781), in which Time Base Corrector (tbc)
It is an object of the present invention to provide a copy-prevention recorded video tape in which a target video cannot be reproduced even when dubbing together.

B. DISCLOSURE OF THE INVENTION Means for Solving the Problems The anti-duplication recorded video tape of the present invention is a recorded video tape to be reproduced by a helical scanning rotary two-head system video tape recorder, by a vertical synchronization signal separation circuit. The width of the separated vertical sync pulse is 1 to 20 μs, and all equalization pulses after the vertical sync pulse and at least part of the horizontal sync pulse in the vertical blanking interval are below the pedestal level. Further, the level is lowered from the last 6 to 14 parts of the video signal to at least a part of the horizontal synchronizing pulse in the vertical blanking interval, or the vertical synchronizing pulse having a width corresponding to the above 1 to 20 μsec. In the later vertical sync signal section
One or a plurality of pulses each having a width of 0.1 to 5 μs are randomly superimposed, or a repetition of a composite video signal in which both are combined is recorded on at least a part of the tape. .

FIG. 1 shows that in a video tape recorded for reproduction by a helical scanning rotary 2-head system video tape recorder, the width of the vertical sync pulse separated by the vertical sync signal separation circuit is 1 to 20 μsec. All the equalization pulses after the vertical sync pulse and at least a part of the horizontal sync pulse in the vertical blanking interval are below the pedestal level (state in FIG. 4), and the last 6 of the video signal L are further included. -14, in the illustrated case, the composite video signal whose level is lowered from the last 10 parts to at least a part of the horizontal synchronizing pulse in the vertical blanking interval.

As shown in FIG. 1, it is appropriate that the level reduction is such that the white level N does not reach the video signal carrier wave zero level 0, that is, about 60 to 80% of the interval.

FIG. 2 shows that the width of the vertical sync pulse separated by the vertical sync signal separation circuit is equivalent to 1 to 20 μsec and all the equalization pulses after the vertical sync pulse and the horizontal sync pulse in the vertical blanking interval are At least a portion is below the pedestal level (state of FIG. 4), and the vertical sync signal section B after the vertical sync pulse having a width of 1 to 20 μs has a width of 0.1 to 5 μs. The pulse W is one to a plurality of pulses, in the case of the figure, eight pulses W, and the composite video signal is randomly superimposed.

The state in which one or more pulses having a width of 0.1 to 5 μs are randomly overlapped means that pulses having different widths, strengths (heights), positions, mutual intervals, etc.
It is a state in which the number is normally 1 to 10, and preferably 5 to 10, different for each vertical synchronization signal section B, and is superposed with no regularity. That is, the superimposition state of the pulse having the width of 0.1 to 5 .mu.sec is completely different between a certain vertical synchronizing signal section and the vertical synchronizing signal sections before and after it.

FIG. 3 also shows that the width of the vertical sync pulse separated by the vertical sync signal separation circuit is equivalent to 1 to 20 μsec and all the equalization pulses after the vertical sync pulse and the horizontal sync pulse in the vertical blanking interval are At least a part of the level is below the pedestal level (state in Fig. 4), and the level is further reduced from the last 6 to 14 parts of the video signal to at least part of the horizontal sync pulse in the vertical blanking interval. An example of a composite video signal in which one or a plurality of pulses having a width of 0.1 to 5 μs are randomly superimposed in the vertical synchronization signal section after the vertical synchronization pulse having a width corresponding to 1 to 20 μs is illustrated. This is a combination of the state described with reference to FIG. 1 and the state described with reference to FIG.

Based on a master tape on which a standard composite video signal is recorded, a known electronic circuit may be used in combination to form the composite video signal as described above, and the implementation is easy.

In the present invention, the first commercially available soft tape
A track is provided in which the repetition of the composite video signal in the state illustrated in FIG. 2, FIG. 2 or FIG. 3 is recorded.

Such a truck can make an illegal dubbing tape substantially meaningless even if it is provided at a key point or a part of the key point (for example, every five minutes for one minute).
It would be perfect if it was placed over the entire roll of videotape. Since the present invention can be automatically carried out by using an appropriate electronic circuit, it is not intentionally partially suitable, but a partial application is also included in the present invention.

When a software vendor calls a tape obtained by duplicating a master tape according to the present invention a modified soft tape, and a tape obtained by dubbing a modified soft tape using two VTRs is called an illegal copy tape, the control signal in the modified soft tape becomes normal. Even if the pulse width is recorded and the pulse width is equivalent to 1 to 20 μs, a normal vertical synchronizing signal exists at the leading edge of the front surface. Therefore, if this is reproduced by the VTR, a normal image can be obtained. However, if you try to dubb a modified soft tape using two VTRs, the vertical sync signal is separated and
The mechanism that divides and generates the control signal does not work,
No control signal is recorded on the illegal copy tape.

Also, due to the electrical resistance and stray capacitance of the cable that connects the two VTRs, the rectangular wave of the vertical sync signal with a pulse width of 1 to 20 μs is integrated and the signal with a low peak and no sharp front rise is illegal. It will be recorded on the copy tape and will no longer function as a vertical sync signal.

In addition, professionals use commercial equipment and
Even if the corrector (TBC) is used together for illegal dubbing, or if an attempt is made for illegal dubbing using a high-end home VCR with TBC, the last 6 to 6 of the video signal adopted in the present invention is used.
Level down from 14 parts to at least part of the horizontal sync pulse in the vertical blanking interval, or 1 to
TBC is disturbed by the random superposition of one or more pulses with a width of 0.1 to 5 μs in the vertical sync signal section after the vertical sync pulse with a width of 20 μs, or by a combination of both, resulting in normal vertical sync. The signal cannot be restored.

For this reason, in the case of a VTR having a servo circuit based on the vertical synchronizing signal, it is impossible to reproduce a normal image from an illegal copy tape dubbed a modified soft tape.

Test example Based on the composite video signal recorded on the commercially available soft tape, the width of the vertical sync pulse separated by the electronic sync circuit by the vertical sync signal separation circuit is 1 to 20 μs and after the vertical sync pulse. Of all the equalization pulses and the horizontal synchronizing pulse in the vertical blanking interval are below the pedestal level, and the vertical blanking interval from the last 6 to 14 parts of the video signal. The level is lowered for at least a part of the horizontal synchronizing pulse, or one or a plurality of pulses having a width of 0.1 to 5 μs are randomly generated in the vertical synchronizing signal section after the vertical synchronizing pulse having a width of 1 to 20 μs. A composite video signal, as shown in FIG. 1, FIG. 2 or FIG. 3, which is either superposed on or combined with each other, is made and recorded on a commercially available tape to make a modified soft tape. When it was produced and reproduced using the following various popular VTRs, it was possible to obtain a normal image on any commercially available television receiver.

VHS system Victor Corp .: BR-7000R Victor Corp .: HRD-380 Matsushita Electric Corp .: F-21 McLeod beta system Sony Corp .: SL-HFR-HiFi Sony Corp .: SL-HF-1000D 8mm Sony Corp .: EV-S700 The above modified soft tape was combined with various VTR luxury devices below and the dubbed tape was played back on a VTR, but it was normal on a commercial television receiver. I couldn't get the video.

Matsushita Electric Co., Ltd .: McLeod S-VHS AG-3750 Matsushita Electric Co., Ltd .: McLeod S-VHS AG-3700 Victor Co., Ltd .: S-VHS BR-S3600 Commercial duplicator (with TBC) c. According to the present invention, it is possible to directly use a recorded video tape legally duplicated according to the present invention to reproduce an image by a VTR, but a tape illegally duplicated from the tape is used for VT.
Even if you try to play the video with R, the screen will be disturbed, so it is not practical. Therefore, illegal copying can be prevented.

It is effective for any VHS system such as VHS system, beta system and 8 mm video which are commercially available. Therefore, V
In addition to dubbing from the HS method to the VHS method and dubbing from the beta method to the beta method, dubbing from the VHS method to the beta method and dubbing from the beta method to the VHS method are also disabled.

The present invention is effective for any television system of NTSC, PAL and SECAM.

[Brief description of drawings]

1, 2 and 3 are diagrams showing examples of waveforms in the vicinity of a synchronizing signal of a composite video signal recorded on the anti-duplication recorded video tape of the present invention, and FIG. 4 is a prior application by the applicant of the present application. FIG. 6 is a diagram showing an example of a waveform in the vicinity of a sync signal of a composite video signal in the invention disclosed in Japanese Patent Application No. 62-187683. FIG. 5 is a diagram for explaining the interlaced scanning on the television screen, FIGS. 6A and 6B show a part of the signal waveform of the television broadcast, and FIG. 6A shows the first interlaced scanning. 6B is a waveform diagram around the sync signal in the field, FIG. 6B is a waveform diagram near the sync signal in the next field, and FIG. 7 is a diagram for explaining the positional relationship between the head and the tape of the helical scanning rotary two-head system VTR. FIG. 8 is a perspective view of the vicinity of the head. FIG. 9 is an explanatory view of a video track recorded on a video tape recorded by a conventional method, and FIG. 10 is a Japanese Patent Application No. 62-187.
FIG. 63 is an explanatory diagram of a video track recorded by the invention disclosed in 683. FIG. 11 is a diagram showing a schematic configuration of a typical servo circuit of a helical scanning rotary two-head system video tape recorder which is currently on the market.

Claims (1)

(57) [Claims] 1. In a recorded video tape for reproduction by a helical scanning rotary two-head system video tape recorder, the width of the vertical synchronization pulse separated by the vertical synchronization signal separation circuit is 1 to 20 .mu.sec. All the equalization pulses after the vertical sync pulse and at least a part of the horizontal sync pulse in the vertical blanking interval are below the pedestal level, and the vertical return is made from the last 6 to 14 parts of the video signal. The level is lowered for at least a part of the horizontal synchronizing pulse in the line erasing section, or the vertical synchronizing signal section after the vertical synchronizing pulse having a width corresponding to 1 to 20 μsec has a pulse having a width of 0.1 to 5 μsec. The repetition of the composite video signal, in which one or more are randomly superimposed or a combination of both, is recorded on at least a part of the tape. The anti-duplication recorded video tape, characterized in that there.