JPS6052626B2 - 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 homes, it cannot be regulated and it is inconvenient for tape manufacturers and copyright holders. It is.

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. These heads 1 and 2 are 1
The magnetic tape 3 is rotated by the motor 5 at a frame frequency, that is, at a rate of 1 month per second, and the magnetic tape 3 is rotated obliquely over an angular range of approximately 1800 with respect to the rotating circumferential surface. It is being 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 synchronizing pulse), and this pulse Pc is supplied to the integrating circuit 22 to form an integral signal Si based on the vertical synchronizing pulse Pv, as shown in FIG. 3D, and this integral signal Si is frequency-divided. The signal is supplied to the circuit 23 and divided into a signal having a frequency of 30H2, and this frequency-divided signal is supplied to the phase/phase comparator circuit 24.
Further, a pulse generating means 26 is provided on, for example, the rotating shaft 6 of the heads 1 and 2, from which a pulse indicating the rotational phase is taken out for each rotation of the heads 1 and 2, and this pulse is supplied to the comparator circuit 24; be done.

In this way, in the comparison circuit 24, the phase of the divided signal from the frequency dividing circuit 23 and the pulse from the generating means 26 are compared,
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, and one field of the video signal Sv from the recording circuit 12 becomes one diagonal magnetic track. And, so that the vertical blanking period is at the end of the magnetic track,
Recorded on tape 3.

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 monitor 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.When the frequency-divided signal is not obtained, that is, the video signal is recorded on the tape 3. When not, the switch circuit 32 is turned off and muting is performed.

In the frequency dividing circuit 23 of the recording system 10 of such a VTR, when obtaining a frequency divided signal from the integral signal Si, a threshold level ζ exists in the frequency dividing circuit 23, and the level of the integral signal Si is at that level. When the threshold 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 3D.
chosen as high as possible, as indicated by TH, i.e.
Of the 6 vertical synchronization pulses Pv, 5 to 6 pulses P
It is configured so that when v is integrated, frequency division is performed. On the other hand, in general television receivers, vertical synchronization is achieved by using a vertical oscillation circuit that oscillates with a vertical period.
This is done by supplying the integral signal Si as is and locking its oscillation phase to the integral signal Si.

Therefore, even if the level of the integral signal Si decreases, the locking range of the vertical oscillation circuit will only become narrower, but the vertical synchronization will not be lost, and there will be no practical problem. 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 Pp, for example, as shown in FIG. There is no problem when watching on a regular television receiver, but if the recorded tape is duplicated, the vertical synchronization will be disrupted when the duplicate tape is played, making it impractical. be.

Let's explain one example below.

In FIG. 2, 50 is the master VTR (0170 for playback).
is a slave VTR (recording VTR) for making recorded tapes.
TR).

Then, the video signal Sv is played back on the master “VTR5O,”
This video signal Sv is supplied to one input contact of the switch circuit 91 through the input terminal 71, and the video signal v from the terminal 71 is supplied to the synchronization separation circuit 81 to generate a synchronization pulse Pc as shown in FIG. 3B. is taken out, and this synchronizing pulse Pc is supplied to a rising trigger type monostable multivibrator 92, and as shown in FIG.
A pulse Pp with a duty ratio greater than 50% and less than 100% is formed and is supplied to the other input contact of the switch circuit 91. 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. 3D, and this signal Si is supplied to the monostable multivibrator 93. As shown in Figure 3E,
A rectangular wave signal Sr is formed that rises relatively early in the integral signal Si and falls near the end of the period T9 of the vertical synchronization 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, and switched to the multivibrator 92 side when the signal Sr is rising. It will be done. Therefore, as shown in FIG. 3F, the video signal Sv from the terminal 71 is taken out from the switch circuit 91 during periods other than the period Tv of the vertical synchronizing pulse Pv.
During the period Tv, the pulse P from the multivibrator 92
p is retrieved.

That is, in the video signal Sv from the switch circuit 91, a part of the vertical synchronizing pulse Pv is replaced with a pseudo vertical synchronizing pulse Pp. This video signal Sv is transmitted to two rotating magnetic heads 61 and 6 through a recording circuit 72, 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 1800 and are rotated by a motor 65 at a rate of 3 mm per second. It is being 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 increased to 30H.
z signal, and this frequency-divided signal (control signal) is supplied to the phase comparator circuit 84. Furthermore, head 6
For example, a pulse generating means 86 is provided on the rotating shaft 66 of the heads 61 and 62, from which a pulse indicating the rotational phase is taken out for each rotation of the heads 61 and 62, and this pulse is supplied to the comparison circuit 84.

In the comparator circuit 84, the phase of the divided signal from the frequency dividing circuit 83 and the pulse from the generating means 86 is compared, and the comparison output is supplied to the motor 65 through the amplifier 87. The video signal Sv (FIG. 3F) whose rotational phase is servo-controlled and is output from the recording circuit 72 has one field as one diagonal magnetic track, and a vertical blanking period at the end of the magnetic track. The image is recorded on the tape 63 as follows.

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 spray 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
If the image is played back using the TR 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 (FIG. 3F) is taken out to the terminal 33, and this signal Sv is sent to the monitor receiver 40.
supplied to In the receiver 40, a pseudo vertical synchronizing pulse P is generated from the video signal Sv as shown in FIG. 3G.
A synchronization pulse Pc with p is taken out, and this pulse P
c is integrated to form an integrated signal S1'' based on the pulse Pp as shown in FIG. 3H, and this signal Si'' is supplied to the vertical oscillation circuit. In this case, this integral signal Si'' is
Although the level is lower than the integral signal Si (FIG. 3D) due to the vertical synchronizing pulse Pv, as described above, the vertical oscillation circuit oscillates in synchronization with the integral signal Si'' even if the level of the integral signal Si'' 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 duplicated tape is reproduced.

That is, the recorded tape 63 is played back on the VTR 3O,
The reproduced video signal Sv (FIG. 3F) 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, the synchronization pulse P of this video signal Sv
In c, the pseudo vertical synchronizing pulse Pp is used, so the integral signal from the integrating circuit 22 becomes the integral signal Si'' in FIG. 3H, which does not reach the threshold level VTH of the frequency dividing circuit 23L. .

Therefore, no frequency-divided signal is obtained from the frequency dividing circuit 23, and therefore this frequency-divided signal is not recorded on the tape 3. Also, servo control of the circuit phases of heads 1 and 2 is not performed.
That is, although the video signal Sv is recorded in the duplication gate 3 by duping, the frequency division signal (control signal) for reproduction servo is not recorded therein. Also, recording servo is not performed. Therefore, this duplicate tape 3 is VT
Since no frequency-divided signal is obtained from the head 28 even after reproduction is performed by R3O, the switch circuit 32 is turned off by the detection circuit 34 and muting is applied, and no video signal Sv is obtained at the terminal 33.

Also, TR3O is a switch circuit 32 for muting.
Even if the model does not have one, servo control of the circuit phase of the heads 1 and 2 is not performed during recording, and servo control is not performed during playback, so the video signal Sv played back from the duplicate tape 3 However, even if it is supplied to the receiver 40, the synchronization of the reproduced image will be disrupted, making it impractical.

Thus, according to the present invention, there is no problem when playing back and viewing the recorded tape 63, but when dubbing the duplicate tape 3 from the recorded tape 63, no reproduced image is obtained, and 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. Moreover, as mentioned 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 intermittently modified, at least the periodicity and level of the horizontal synchronizing pulse during the vertical synchronizing signal period have the same periodicity and level as before modification. Horizontal A
It may adversely affect the operation of the FC circuit, or
There is no adverse effect such as disturbance of so-called interlaced scanning when switching between even fields. FIG. 4 shows another example of the invention.

That is, in this example, the pulse Pp from the monostable multivibrator 92 is supplied to the set terminal S of the rising trigger type RS flip-flop circuit 95 with set priority, and the synchronous pulse from the synchronous separation circuit 81 is Pc is a flip-flop circuit. "95 is supplied to the reset terminal R. Therefore, the flip-flop circuit 9
5, as shown in Figure 5D (Figures 5A-C are the 3rd
Same as Figures A-C) rises at pulse Ps, pulse Ps
A pulse Pf that falls at the pulse Pr when there is no pulse is obtained.

This pulse Pf is then supplied to the other input contact of the switch circuit 91.

Further, a signal Sr (FIG. 5E) from the monostable multivibrator 93 is supplied to the switch circuit 91 as its control signal. Therefore, as shown in FIG. 5F, from the switch circuit 91, a video signal Sv in which a part of the vertical synchronizing pulse Pv has been replaced with a pseudo vertical synchronizing pulse Pf is taken out and recorded on the tape 63, and the video signal Sv is recorded on the tape 63. It is referred to as tape 63.

Therefore, when the synchronization pulse Pc of this recorded tape 63 is separated and integrated, the integrated signal Si'' becomes as shown in FIG. , there is no problem, but when dubbing is performed, the duplicated tape 3 will not be reproduced again or the synchronization will be disrupted, making it unusable. In other words, dubbing can be prevented.

If the circuit described in FIG. 2 or 4 is incorporated into a general VTR, it is possible to prevent dubbing of tapes recorded by individuals from television broadcasts and the like.

Furthermore, in the circuits of FIGS. 2 and 4, the synchronization pulse P
c may be obtained from an external synchronization board. Furthermore, in the video signal Sv of FIG. 5F, the height of the pulse Pf may be higher than the other synchronizing pulses Pc. Furthermore, 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 the drawing]

FIG. 1 is a system diagram of an example of a VTR, FIGS. 2 and 4 are system diagrams of an example of the present invention, and FIGS. 3 and 5 are waveform diagrams for explaining the same. 72 is a recording circuit, 80 is a servo circuit, and 92 and 93 are monostable multivibrators.

Claims (1)

[Claims] 1. A part of the vertical synchronizing signal is intermittently transformed while maintaining the periodicity and level of the horizontal synchronizing pulse, and its integral value is equal to the integral value of the vertical synchronizing signal before being transformed. A recorded medium on which a video signal is recorded that does not reach a certain level so that it cannot be properly recorded on a VTR, etc. 2 Separate the synchronization signal from the video signal, intermittently transform a part of the vertical synchronization signal based on this synchronization signal while maintaining the periodicity and level of the horizontal synchronization pulse, and integrate the vertical synchronization signal. A method for producing a recorded recording medium for recording a video signal whose value does not reach the level of the integrated value of a vertical synchronization signal before transformation.