JPS6052627B2 - Recorded recording medium and its production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION With the spread of VTRs (magnetic recording and reproducing devices), pre-recorded video tapes containing movies and the like are being sold.

However, if two VTRs are prepared, copies can be easily dubbed from recorded tapes. Although this kind of dubbing of recorded tapes is prohibited by law, if it is done on a small scale in ordinary households,
This cannot be regulated and is inconvenient for tape manufacturers and copyright holders.

In view of these points, the present invention aims to provide a recorded tape that cannot be dubbed, and a method for producing the same. First, if we consider a general VTR, it is constructed as shown in FIG.

That is, in FIG. 1, 10 indicates the recording system, and the third
A video signal Sv (Pc is a synchronizing pulse) shown in FIG.

The heads 1, 2 have an angular spacing of 1800 and are rotated by a motor 5 at a frame frequency, i.e. 3 degrees per second, and the magnetic tape 3 has an angular spacing of approximately 1800. It is routed diagonally over an angular range of , and is transported at a constant speed. Further, 20 indicates a servo circuit, and the video signal Sv from the terminal 11 is supplied to the sync separation circuit 21, and as shown in FIG. 3B, a sync pulse Pc (Ph is a horizontal sync pulse, Pe is an equalization pulse, Pv is a vertical synchronization pulse) is taken out, and this pulse P
c is supplied to the integrating circuit 22, as shown in FIG. 3E,
An integral signal Si is formed by the vertical synchronizing pulse Pv, and this integral signal Si is supplied to the frequency dividing circuit 23 to increase the frequency by 3.
The frequency is divided into a signal of 0H2, and this frequency-divided signal is supplied to the phase comparator circuit 24. Furthermore, a pulse generating means 26 is provided on, for example, the rotating shaft 6 of the heads 1 and 2, and from this, a pulse indicating the rotational phase of each rotation of the heads 1 and 2 is taken out, and this pulse is supplied to the comparator circuit 24. Ru.

In this way, in the comparator circuit 24, the phase of the divided signal from the frequency dividing circuit 23 and the pulse from the generating means 26 is compared, and the comparison output is supplied to the motor 5 through the amplifier 27, thereby causing the heads 1 and 2 to rotate. The video signal Sv whose phase is servo-controlled and is output from the recording circuit 12 is recorded on the tape 3 so that one field becomes one diagonal magnetic track and a vertical blanking period occurs at the end of the magnetic track. recorded.

At this time, the frequency division signal from the frequency division circuit 23 is supplied to the magnetic head 28, and the frequency division signal is recorded on the tape 3 as a magnetic track in the length direction of the tape 3.

On the other hand, 30 indicates a reproduction system.

That is, the head 28 outputs the frequency-divided signal (
control signal) is regenerated, and this frequency-divided signal is supplied to the comparator circuit 24, and the pulse from the generating means 26 is supplied to the comparator circuit 24, and these frequency-divided signals and pulses are compared in phase, and the comparison output is supplied to the motor 5 through the amplifier 27, whereby the rotational phases of the heads 1 and 2 are servo-controlled, so that the magnetic tracks of the video signal Sv on the tape 3 are correctly scanned by the heads 1 and 2. In this way, the video signal Sv is reproduced from the tape 3 by the heads 1 and 2, and this video signal Sv passes through the reproduction circuit 31 and the muting switch circuit 32 to the output terminal 33.
It is taken out and further supplied to the receiver 40.

In this case, the frequency-divided signal from the head 28 is sent to the detection circuit 3.
4, the presence or absence of the frequency-divided signal is detected, and the detection signal is supplied to the switch circuit 32 as its control signal. If not, switch circuit 3
2 is turned off and mutating is performed.

In the frequency dividing circuit 23 of the recording system 10 of such a TR,
When obtaining a frequency divided signal from the integral signal Si, the frequency dividing circuit 2
3 has a threshold level, and the integral signal Si
The level is the threshold. When the current level is exceeded, division is performed.

In order to prevent malfunctions in VTRs, this threshold level is set to the level V shown by the broken line in Figure 3E.
chosen as high as possible, as indicated by TH, i.e.
It is configured such that frequency division is performed when 5 to 6 pulses Pv out of 6 vertical synchronizing pulses Pv are integrated. On the other hand, in general television receivers, vertical synchronization is performed by supplying the integral signal S1 as is to the vertical oscillation circuit that is oscillating in vertical synchronization, and locking the oscillation phase to the integral signal Si. There is.

Therefore, even if the level of the integral signal Si decreases, the locking range of the vertical oscillation circuit will only become narrower, and the vertical synchronization will not be lost, so there is no problem in practice. Focusing on these points, the present invention replaces a part of the vertical synchronizing pulse Pv on the recorded tape with another pseudo vertical synchronizing pulse IPS, for example as shown in FIG. There is no problem when viewing on a general television receiver, but if the recorded tape is duplicated, the vertical synchronization will be disrupted when the duplicate tape is played back, making it impractical.

An example of this will be explained below.

In FIG. 2, 50 is a master TR (playback VTR);
Reference numeral 70 indicates a slave VTR (recording VTR) for producing a recorded tape.

Then, the video signal Sv is reproduced by the master TR5O, and this video signal Sv is transmitted to the switch circuit 9 through the input terminal 71.
At the same time, the video signal Sv from the terminal 71 is supplied to the sync separation circuit 81, and the sync pulse Pc is taken out as shown in FIG. 3B. 92 and as shown in FIG.
is formed, and this pulse Pd is sent to the sawtooth signal forming circuit 9.
3, as shown in FIG. input contacts. Further, the synchronizing pulse Pc from the separation circuit 81 is supplied to the integrating circuit 82 to form an integral signal Si based on the vertical synchronizing pulse Pv as shown in FIG. 3E, and this signal Si is supplied to the monostable multivibrator 94. As shown in FIG. 3F, a rectangular wave signal Sr is formed which rises relatively early in the integral signal Si and falls near the end of the period Tv of the vertical synchronizing pulse Pv.

This signal Sr is then supplied to the switch circuit 91 as its control signal, and the switch circuit 91 is switched to the terminal 71 side when the signal Sr is falling.
When it is rising, it is switched to the forming circuit 93 side. Therefore, as shown in FIG. 3G, from the switch circuit 91, the video signal Sv from the terminal 71 is taken out during the period excluding the period Tv of the vertical synchronizing pulse Pv, and during the period Tv.
The pulse Ps from the forming circuit 93 is taken out at v. That is, the video signal Sv from the switch circuit 91 is
A part of the vertical synchronization pulse Pv is a pseudo vertical synchronization pulse Ps
has been replaced by Then, this video signal Sv is transmitted through the recording circuit 72 to two rotating magnetic heads 61 and 6, for example.
2.

The heads 61, 62 and their servo circuit 80 are connected to the first
It is configured similarly to the VTR shown in the figure, and the head 61
, 62 have an angular spacing of 180 degrees and are rotated by a motor 65 at a rate of 3 (2) per second, and the magnetic tape 63 has an angular range of approximately 180 degrees with respect to its rotating circumferential surface. It is passed diagonally across and transported at a constant speed.

Further, in the servo circuit 80, the integral signal Si from the integrating circuit 82 is supplied to the frequency dividing circuit 83, and the frequency is 30Hz.
This frequency-divided signal (control signal)
is supplied to the phase comparison circuit 84. Furthermore, the head 61
, 62 is provided with a pulse generating means 86, for example, on the rotating shaft 66 of the heads 61, 62, from which a pulse indicating the rotational phase is taken out for each rotation of the heads 61, 62, and this pulse is supplied to a comparator circuit 84.

Then, in the comparison circuit 84, the phase of the divided signal from the frequency dividing circuit 83 and the pulse from the generation means 86 is compared, and the comparison output is supplied to the motor 65 through the amplifier 87, thereby causing the rotational phase of the heads 61, 62. The video signal Sv (FIG. 3G) is servo-controlled and output from the recording circuit 72, so that one field becomes one diagonal magnetic track, and a vertical blanking period occurs at the end of the magnetic track. is recorded on the tape 63.

At this time, the frequency division signal from the frequency division circuit 83 is supplied to the magnetic head 88, and the frequency division signal is recorded on the tape 63 as a magnetic track in the length direction of the tape 63. In this way, the video signal Sv from the master VTR 5O is transferred to the slave TR
At step 7O, the information is recorded on the tape 63, that is, the recorded tape 63 is produced.

The recorded tape 63 produced in this way is
When played back on the VTR shown in the figure, the image can be played back without any problems.

That is, when the recorded tape 63 is played back by the playback system 30, the played video signal Sv (G in FIG. 3) is taken out to the terminal 33, and this signal Sv is sent to the monitor receiver 40.
supplied to Then, in the receiver 40, a pseudo vertical synchronizing pulse P is generated from the video signal Sv as shown in FIG. 3H.
A synchronizing pulse Pc with s is taken out, and this pulse P
c is integrated to form an integrated signal Si'' based on the pulse Ps, as shown in FIG. 3, and this signal Si'' is supplied to the vertical oscillation circuit. In this case, this integral signal Si'' is an integral signal Si (FIG. 3E) due to the vertical synchronizing pulse Pv.
However, as mentioned above, the vertical oscillation circuit oscillates in synchronization with the integrated signal Si'' even if its level is low. Therefore, the image on the recorded tape 63 is correctly reproduced on the receiver 40. On the other hand, if this recorded tape 63 is duplicated, correct images cannot be reproduced even if the duplicate tape is reproduced.

That is, the recorded tape 63 is played back on the VTR 3O,
The reproduced video signal Sv (Fig. 3G) is transferred to a VTRl
If the video signal Sv is supplied to O, the video signal Sv will be recorded on the tape 3. However, at this time, since the synchronizing pulse Pc of this video signal Sv is a pseudo vertical synchronizing pulse Ps, the integral signal from the integrating circuit 22 becomes the integral signal S1'' in FIG. It does not reach the threshold level TH of circuit 2) 3. Therefore, no frequency-divided signal is obtained from the frequency divider circuit 23, and therefore this frequency-divided signal is not recorded on the tape 3. Servo control of rotational phases 1 and 2 is also not performed.In other words, although the video signal Sv is recorded on the duplicate 5 tape 3 by duping, the frequency division signal (control signal) for the reproduction servo is not recorded. Also, recording servo is not being performed.
Therefore, even if this duplicate tape 3 is played back on the VTR 3O,
Since the frequency-divided signal cannot be obtained from the head 28, the detection circuit 3
4, the switch circuit 32 is turned off and muting is applied, and the video signal Sv is not obtained at the terminal 33.

In addition, the VTR3O is a switch circuit 3 for muting.
Even if the model does not have head 2, heads 1 and 2 are used during recording.
Since rotational phase servo control is not performed and servo control is not performed during this reproduction, even if the video signal Sv reproduced from the duplicate tape 3 is supplied to the receiver 40, the synchronization of the reproduced image is not performed. is disorganized and is of no practical use. Thus, according to the present invention, there is no problem when playing back and viewing the recorded tape 63, but when duplicating the duplicate tape 3 from the recorded tape 63, no reproduced image is obtained. Even if it were obtained, the synchronization would be disrupted and it would not be of practical use. Therefore, even if duplication is performed, only a completely useless duplicate tape 3 will be produced, and duplication can be prevented. Furthermore, as described above, dubbing can be prevented no matter what type of VTR is used for dubbing. According to the present invention, although the vertical synchronizing pulse is modified into a sawtooth waveform, at least the periodicity and level of the horizontal synchronizing pulse in the vertical synchronizing signal period have the shape and level before modification, so that There is no adverse effect on the operation of the horizontal N°C circuit or disturbance of so-called interlaced scanning when switching between odd and even fields. Incidentally, if the circuit explained in FIG. 2 is incorporated into a general TR, it is possible to prevent dubbing of tapes recorded by individuals from television broadcasts and the like.

Furthermore, in the circuit of FIG. 2, the synchronization pulse Pc may be obtained from an external synchronization board. Further, instead of the tape 63, a recording medium such as a magnetic card or a so-called video disk may be used.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an example of a VTR, FIG. 2 is a system diagram of an example of the present invention, and FIG. 3 is a waveform diagram for explaining the same. 72 is a recording circuit, 80 is a servo circuit, 92 is a differential circuit,
93 is a sawtooth signal forming circuit, and 94 is a monostable multivibrator.

Claims (1)

[Claims] 1. Deforming a part of the vertical synchronization pulse into a sawtooth waveform while maintaining the periodicity and level of the horizontal synchronization pulse,
A recorded recording medium that records a video signal whose integral value does not reach the level of the integral value of the vertical synchronization signal before transformation. 2 Separate the synchronization signal from the video signal, transform a part of the vertical synchronization pulse into a sawtooth waveform while maintaining the periodicity and level of the horizontal synchronization pulse based on this synchronization signal, and transform the vertical synchronization signal into A method for producing a recorded recording medium for recording a video signal in which the integral value does not reach the level of the integral value of a vertical synchronizing signal before transformation.