JPS6011511B2 - Recorded recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION With the spread of VTRs (recording and reproducing machines), pre-recorded video tapes containing movies and the like are now on sale.

However, if two VTRs are used, copies of recorded tapes can be easily dubbed.
Dubbing of recorded tapes like this is prohibited by law, but 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. First, if we consider a general VTR, it is constructed as shown in FIG.

That is, the recording system is shown at 10' in the figure, and the video signal Sv shown in FIG. 2A.

(Pc. is a synchronization pulse) is supplied from the input terminal 11 to the two rotating magnetic heads 1 and 2 through the recording circuit 12, for example. The heads 1 and 2 have an angular spacing of 180 degrees and are rotated by a motor 3 at a frame frequency, that is, 30 times per second. and is transported at a constant speed. In the Futagawa servo circuit, terminal T
The video signal Sv from 1.

is supplied to the synchronization separation circuit 21, and a synchronization pulse Pco (PH is a horizontal synchronization pulse, PE is a writing pulse, and Pv is a vertical synchronization pulse) is extracted as shown in FIG. As shown in FIG. 2D, the product 0 minute signal S, is generated by the vertical synchronizing pulse Pv. is formed, and this integral signal S, . is supplied to the frequency dividing circuit 23 and the frequency is 3.
A 0HZ signal is formed and supplied to the phase comparator circuit 241. On the other hand, a pulse generating means 25 is provided on, for example, the rotating shaft 5 of the heads 1 and 2, from which a pulse indicating the rotational phase of each rotation of the heads 1 and 2 is obtained, and this pulse is supplied to the phase comparator circuit 24. . Then, in the phase comparison circuit 24, the phase of the 30Hz signal from the frequency dividing circuit 23 and the pulse from the pulse generation means 25 is compared, and the comparison output is supplied to the motor 3 through the amplifier 026. With the rotational phase controlled, the video signal Svo from the recording circuit 12 is recorded on the tape in such a way that one field becomes one diagonal magnetic track, and a vertical blanking period is left at the end of the magnetic track. Recorded in 4. Further, the signal from the frequency dividing circuit 23 is supplied to the magnetic head 27, and the signal is output from the magnetic head 27.

4 is recorded as a control signal in green.

On the other hand, 30 indicates a reproduction system, in which a control signal is reproduced from the tape 4 by the head 27 and supplied to the phase comparator circuit 24, and a pulse from the pulse generating means 25 is supplied to the phase comparator circuit 24. , in the circuit 24, the phases of these are compared, and the comparison output is supplied to the motor 3 through the amplifier 26, thereby controlling the rotational phase of the heads 1 and 2, so that the heads 1 and 2 are aligned with the magnetic track of the video signal Svo. will be scanned correctly.

In this state, the video signal Svo is reproduced from the tape 4 by the heads 1 and 2, and this reproduced signal is transmitted to the reproduction circuit 31.
The signal is taken out to the output terminal 32 through the four channels, and is further supplied to the monitor receiver.

In the frequency dividing circuit 23 of the recording system 10 of the VTR, the integral signal S,. When obtaining a frame frequency signal from the frequency dividing circuit 23, a threshold level exists, and when the level of the integrated signal S, o exceeds the threshold level, frequency division is performed. And VTR
In order to prevent malfunctions, this threshold level is chosen as high as possible, as shown by the broken line level VTH in FIG. , 5 to 6 pulses are integrated, frequency division is performed.

On the other hand, in general television receivers, vertical synchronization is achieved by supplying the integral signals S and o as they are to a vertical oscillator that oscillates with a vertical period, and changing the oscillation phase to the integral signal S.
, o. Therefore, the integral signal S
,. Even if the level of is lowered, the lock range of the vertical oscillator will only become narrower, and the vertical synchronization will not be lost, so it is considered that this is not a problem in practice. Focusing on this point, for example, by triggering a monostable multipipulator with a synchronization pulse Pco separated from the video signal Svo,
As shown in FIG. 2C, a second
As shown in Figure E, the integral signal S,.

The period T of the vertical synchronizing pulse Pv rises relatively early in
A rectangular wave signal SR that falls near the end point of v is formed, and a pulse PP is replaced and inserted in the rising section of this signal SR as a vertical synchronizing pulse Pv. Synchronous pulse Pv'
The idea was to produce a recorded tape by recording the video signal Sv' (FIG. 2F) having .
According to this recorded tape, by recording on the tape a 30Hz control signal formed from, for example, the original vertical synchronization pulse Pv, when the recorded tape itself is played back, the playback system At 30, the desired tracking servo is performed, so there is no problem.

On the other hand, when dubbing this recorded tape, during recording, the synchronization pulse Pc' shown in FIG. 2G is taken out from the synchronization separation circuit 21 of the recording system 10, and the integrated signal As SI^, as shown in FIG. 2, the integrated value is small and does not reach the threshold level of the frequency dividing circuit 23, VTH, so that no frequency divided signal can be obtained from the frequency dividing circuit 23. Therefore, the rotational phases of the heads 1 and 2 are not controlled, and no control signal is recorded on the tape 4. Therefore, even if the duplicate tape 4 is played back, the playback control signal from the head 27 is not obtained in the playback system 301, so the tracking servo is not applied during playback, and the reproduced image on the receiver 40 is It becomes unbearable to watch. By the way, as mentioned above, if all the vertical synchronizing pulses of the video signal recorded on the recorded tape are replaced with pulses Pv' whose integral value is small, the receiver 40's Even if the vertical oscillator oscillates synchronously even with signals S and A with small integral values, depending on the receiver and the integral value, synchronization may not be achieved and the image may drift or rotate.

Therefore, when using the above-mentioned recorded tape, problems arise on the receiver 40' even when the tape itself is played back. In view of this point, the present invention does not replace all the vertical synchronizing pulses of the video signal recorded on the recorded tape with pulses whose integral value is small, but replaces them only in some fields. It is.

A specific example will be explained below.

FIG. 3 shows a recording VTR for producing an example of a recorded tape according to the present invention, and 1 1 1 is its input terminal, which is obtained from a television camera.

Alternatively, a video signal before being replaced with a vertical synchronizing pulse obtained from a reproducing VTR is supplied. The video signal Svo from the input terminal 111 (the number fields are schematically shown in FIG. 2A...FIG. 4A) is supplied to one input terminal of the switch circuit 51, and This video signal Sv.

is supplied to the synchronization separation circuit 121, and the synchronization pulse Pco(
B) in FIG. 2 is taken out and supplied to the monostable multipipulator 52 to form a pulse PP (C in FIG. 2) synchronized with the horizontal synchronizing pulse PH, which is supplied to the other input terminal of the switch circuit 51. be combined. Synchronous separation circuit 12
The synchronization pulse Pco from 1 is also supplied to an integrating circuit 122 to produce an integral signal S, according to the vertical synchronization pulse Pv. (
FIG. 2D...FIG. 4B) is formed, and this is supplied to the monostable multipipulator 53, and the integral signal S,o
rises relatively early in the period Tv of the synchronizing pulse Pv.
Pulse SR falls near the end of (Fig. 2 E...
...Figure 4C) is formed. And this pulse S
R is supplied to the AND circuit 54 as V. Furthermore, this pulse SR is supplied to the OR circuit 55, and furthermore, the counter 5
6, the counter 56 sets the pulse SR to 3, for example.
Every time 0 is counted, that is, every 0.5 seconds, a pulse Sx (D in FIG. 4) is obtained from the pulse forming circuit 57 on the output side at a position shifted from the pulse SR, and this is output from the OR circuit 55.
supplied to Then, the output signal SY (FIG. 4E) of the OR circuit 55 is supplied to the flip-flop circuit 58 and is inverted for each pulse SR, and the inverted phase is 0.
．． The signal SF (which changes every 5 seconds and every 30 fields)
Figure 4F) is obtained. This signal SF is the AND circuit 64
pulses SR are extracted every other pulse, and the phase of the extraction is 0. A signal SG (FIG. 4G) whose state changes each time the stage is ascended is obtained.
3, and this signal SG is sent to the switch circuit 51.
The switch circuit 51 is switched to the input terminal 111 side when the signal SG is falling, and to the monostable multipipulator 52 side when the signal SG is rising.

Therefore, as a vertical synchronizing pulse, from the switch circuit 51, every other field has the original pulse Pv, and the fields in between have the replaced pulse Pv', and the replaced field is an odd number. Field or even field is 0
．． A video signal Sv (shown schematically in FIG. 4, H', and the state when it is replaced is as shown in FIG. 2) is taken out every 9 seconds. This video signal Sv is then supplied to, for example, two rotating magnetic heads 101 and 102 through the recording circuit 112. This head 101
and 102 and its servo circuit 120 are constructed in the same way as the recording system 10 in FIG. 1, and corresponding parts are indicated by 100 more symbols than those in FIG.

However, in this case, the integral signal supplied to the frequency dividing circuit 123 is formed by the integrating circuit 122 from the original synchronization pulse Pco obtained from the synchronization separation circuit 121. Therefore, the video signal Sv (FIG. 4H) is transmitted to the tape 104.
A predetermined pattern is recorded on the tape 104, and a 30 Hz signal obtained from the frequency dividing circuit 123 is recorded as a control signal, thereby producing a recorded tape.

When the recorded tape 104 produced in this way is played back by the VTR shown in FIG. 1, the playback system 30 can play it without any problems as long as all the vertical synchronizing pulses of each field are replaced. The same is true.

Then, the reproduction signal Sv from the reproduction system 30 is transmitted to the monitor receiver 4.
0, the receiver 40 receives a synchronization pulse P with the vertical synchronization pulse replaced every other field.
c (the replaced part is shown in Fig. 2G) is taken out and integrated, and the integral value takes 4 and 2 values alternately for each field, and for example, every 0.9 sand, it takes a large value. An integral signal S in which the peak of the value continues for two fields (Fig. 4 1...Fig. 2 D shows the state when the integral value is large, and Fig. , respectively) are formed and fed to the vertical oscillator. For this reason, the vertical oscillator of the receiver can oscillate reliably in synchronization with the vertical synchronization pulse, even though it may be difficult to synchronize in areas where the integral value is small, since there are areas where the integral value is large every other field. do.

Therefore, the image on the recorded tape 104 can be correctly reproduced on the receiver 40'. On the other hand, this recorded tape 104
If you dub the tape, the correct image will not be reproduced even if you play the duplicate tape.

That is, when the recorded tape 104 is reproduced by the reproduction system 30 and the reproduced video signal Sv (H in FIG. 4) is supplied to the recording system 10, the video signal Sv is recorded on the tape 4.

However, at this time, the synchronization pulse Pc of this video signal Sv
has a vertical synchronizing pulse Pv' that is replaced every other field, and its integral value does not reach the thread J short level VTH of the frequency divider circuit 23 every other field.
Therefore, the signal Sc obtained from the frequency dividing circuit 23 (Fig. 4 J
) is inverted every two fields, that is, has a period of two frames, and the inversion phase changes every 0.9 fields. Therefore, heads IZ and 2 during recording
The rotation phase of the servo is disturbed, and the control pulses recorded on the tape 4 do not correspond to the track pattern at all. Therefore, when this duplicate tape 4 is played back by the playback system 30, since the playback control signal from the head 27 does not correspond to the track pattern,
The tracking servo during playback is useless, and the receiver 40
The reproduced image becomes unbearable to watch. The example in FIG. 5 shows a recording VTR for producing another example of the recorded tape according to the present invention. In other words, every two fields, the pulse Pv' is replaced with a pulse Pv' whose integral value becomes smaller. That is, the pulse SR from the monostable multipipelator 53 (FIG. 6C, in which A and 8 correspond to FIGS. 4 A and B) is supplied to the AND circuit 54, and this pulse SR is supplied to the counter 66. and every time the counter 66 counts, for example, three pulses SR, that is, every three fields, the pulse forming circuit 67 on the output side outputs a pulse S
z (FIG. 6D) is obtained and supplied to the AND circuit 54.

Then, a signal SG (FIG. 6E) in which every second pulse SR is extracted from the AND circuit 54 is obtained. This signal SG is then supplied as a switching signal to the switch circuit 51, and the switch circuit 51 is switched to the input terminal 111 side when the signal SG is falling, and to the monostable multipipulator 52 side when the signal SG is rising. .

Therefore, the switch circuit 51 outputs a video signal as a vertical synchronizing pulse, which has the original pulse Pv in two of the three fields, and has the replaced pulse Pv in the remaining one field. Sv (schematically shown in FIG. 6F; its state when replaced is as shown in FIG. 2F) is taken out. Then, this video signal Sv passes through the recording circuit 112 to the head 101.
and 102.

The other parts are exactly the same as those in FIG. Therefore, even when using the recorded tape 104 manufactured in this way, the third
Similarly to the one produced by the VTR shown in the figure,
There is no problem when playing back and viewing the recorded tape 104 itself, but on the other hand, when dubbing it,
The reproduced image becomes unbearable to view.

In addition, FIG. 6 shows the control signal Sc recorded on the duplicate tape during dubbing recording. As described above, according to the recorded tape of the present invention, there is no problem at all when playing back and viewing the recorded tape itself, and there is no inconvenience in particular on a television receiver; If a duplicate tape is dubbed from the original, a completely useless duplicate tape will be created, and dubbing can be prevented.

There is also a type of VTR in which the control signal to be recorded on the tape is formed from the pulses from the above-mentioned pulse generating means 25, but even in this case, when recording dubbing, the head 1 is Since the servo of the rotational phase of 2 and 2 is disturbed, the control signal recorded on the duplicate tape does not correspond to the track pattern at all, and as described above, dubbing can only result in a useless duplicate tape. Therefore, according to the recorded tape of the present invention, dubbing by any VTR can be prevented. Note that the circuit for replacing the vertical synchronizing pulse shown in FIG. 3 or FIG. 5 may be configured to be added as an adapter to a general VTR.

Further, instead of the tape, a recording medium such as a magnetic card or a so-called video disk may be used.

[Brief explanation of the drawing]

Figure 1 is a system diagram of an example of a VTR, Figure 2 is a waveform diagram for its explanation, Figure 3 is a system diagram of a VTR that produces an example of the recorded tape of this invention, and Figure 4 is its explanation. FIG. 5 is a system diagram of a VTR for producing another example of the recorded tape of the present invention, and FIG. 6 is a waveform diagram for explaining the same. 112 is a recording circuit, 120 is a servo circuit, 121 is a synchronization separation circuit, 122 is an integration circuit, 52 and 53 are monostable multipipeters, 56 and 66 are counters, 57 and 67 are pulse forming circuits, and 58 is a flip-flop circuit. be. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 n (where m is an integer greater than or equal to 2) field
(where n is a positive integer smaller than m) field, there is a vertical synchronization pulse whose integral value is relatively large, and the remaining fields have a vertical synchronization pulse whose integral value is relatively small. A recorded recording medium on which a video signal having a video signal is recorded.