JPS6349953B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal (video signal format such as PCM recording of an audio signal) recorded on a magnetic tape by a rotating head type magnetic recording/reproducing device (hereinafter referred to as VTR). (including cases where it has been converted to
In particular, it allows reproduction at a faster speed than the tape speed at which it was recorded.

Conventionally, there are two methods for duplicating video tapes:
There are seeds. The first is to line up many VTRs and
This is a so-called VTR-VTR recording method in which the playback signal from the main VTR is recorded on each VTR. The second method is a duplication method that does not use head recording, by bringing the master tape on which the original signal has been recorded and the unrecorded slave tape into contact with each other's magnetic surfaces, and applying a magnetic field or heat to transfer the signals from the master tape to the slave tape. This is a contact transfer method.

Recently, VTRs have become extremely popular, and mass duplication is required to supply a large amount of video software (recorded tapes).
In the first method, it takes real time to copy, which increases the cost, whereas in the second method, it does not require real time to copy, and therefore video software can be created at low cost, so it will become more expensive in the future. It is thought that it will become mainstream.

However, the popularity of VTRs in homes has increased significantly for portable types that come with video cameras, and these VTRs are often used to record and enjoy video by oneself. Then, a request arises to duplicate the recorded tape and send it to friends and family.
In such cases, it would be very convenient if there was a device that could easily reproduce magnetic tapes at home. In this case, since there is no mass duplication, the first method is used.
The VTR-VTR recording method is advantageous in terms of equipment scale. For VTR-VTR duplication, prepare two VTRs,
This can be done by loading a recorded tape into the first VTR and putting it into playback mode, and using the playback signal as the input signal for the second VTR, by loading an unrecorded tape into the second VTR and putting it into recording mode. . In this case, the time required for duplication is the same real time as the recording time of the recorded tape, making the duplication work cumbersome. Furthermore, in order to speed up VTR-to-VTR duplication, devices have been proposed in which the number of rotating heads is increased and the diameters of the rotating head cylinders are varied (for example, Japanese Patent Laid-Open No. 54-25717). for
It would be too complicated to mass produce as a VTR duplicating device.

The present invention addresses the above-mentioned needs and solves the problems of the prior art, and provides a device that allows videotape duplication to be performed using a simple device in a shorter time than the recording time.

Hereinafter, the present invention will be explained with reference to the drawings. Figure 1 is a diagram showing the relative relationship between the rotating head and magnetic tape of an azimuth recording VTR, which is currently popular for home use, and Figure 2 shows the relative relationship between the rotary head and the magnetic tape.
FIG. 2 is a diagram schematically showing a tape pattern recorded by a VTR. Rotating cylinder 1 is on the outer circumference
Rotary heads 2 and 3 are mounted so as to maintain a 180° positional relationship, and rotary cylinder 1 rotates in the direction of arrow A at 30 revolutions per second. Rotating heads 2 and 3
The gap has different inclination angles, and is represented by R and L, for example. A video signal recorded with the R rotary head cannot basically be reproduced with the L rotary head, and can only be reproduced with the R rotary head. will be played. The magnetic tape 4 is wound around approximately half the circumference of the rotating cylinder, and is arranged at a predetermined angle of inclination with respect to the rotating cylinder as shown by arrow B.
It is configured to run at a constant speed in a direction. Therefore, for example, the track pattern recorded by the rotary head 3 becomes a track inclined with respect to the magnetic tape 4 as shown at 5. Figure 2
R ₁ , L ₁ , R ₂ , L ₂ , R ₃ , L ₃ designate the tracks thus recorded by the rotating heads 2 and 3, and R ₁ , R ₂ , R ₃ are the azimuth angles. is the track recorded by the rotating head 2 of R,
Tracks L ₁ , L ₂ and L ₃ are of azimuth angle L recorded by the rotary head 3. Video signals are recorded on these tracks, and are usually a signal obtained by superimposing a signal obtained by frequency modulating a luminance signal and a signal obtained by low-frequency conversion of a carrier color signal. magnetic tape 4
In addition to this video signal, there are a control track 6 and an audio track 7, and the control signal and audio signal are recorded by separate fixed heads.

FIG. 2 is a view of the magnetic tape 4 seen from the magnetic surface, with arrow B indicating the running direction of the magnetic tape and arrow A indicating the running direction of the rotary head.

Now, let us consider the case where a magnetic tape recorded as shown in FIG. 2 is to be reproduced. The tape speed V _T and the rotating head speed V _H are the same as during recording, and the positional relationship between the rotating head and the magnetic tape is kept constant by a servo loop using the control signal recorded on the control track 6 and the rotating cylinder position signal. It is well known that if the rotary heads 2 and 3 are controlled in the correct manner, they will correctly scan the recorded tracks R ₁ , L ₁ , R ₂ , L ₂ , . . . and the video signal will be correctly reproduced. be. It is possible to duplicate the video signal that has been correctly played back in this way by recording it on another VTR, but
In this case, it takes the same amount of time to reproduce the parent tape as it does to record it, resulting in a long duplication time.

The present invention makes it possible to shorten the duplication time, and in principle it can be shortened to any desired time, but here, for convenience of explanation, a case where the duplication time is shortened to 1/2 will be taken as an example.

In order to reduce the duplication time to 1/2, it is necessary to shorten the playback of the parent tape to 1/2 of the recording time and record on the child tape at the same time. In short, all you have to do is cut the playback time in half without losing all the video information on the parent tape.
To reduce the playback time to 1/2, the playback tape speed must be twice the recording speed.

Consider the case where a tape having the recording pattern shown in FIG. 2 is played back at double speed. Since the control signal on control track 6 and the audio signal on audio track 7 are reproduced by a fixed head, = υ/λ λ: Recording wavelength υ: Tape speed: From the relationship of frequency, the frequency only doubles. If the data is recorded on a non-tape running at double speed, the child tape will have the same signal as the parent tape, and duplication will have been performed.

However, the video signal depends on the speed of the rotating head.
Since V _H is the same as during recording and the tape speed V _T is doubled, the trajectory of the rotary head straddles the two recording tracks as shown at 8, 9, and 10 surrounded by the broken line in Figure 2. It becomes a vine. Now, if the scanning trajectory 8 has an azimuth angle R, then the scanning trajectory 9
is alternately switched to L and 10 to R. The rotary head output when the playback tape is run at twice the speed is shown in FIGS. 3a and 3b in comparison with the head switch signal used to switch the rotary head.
A in the figure is a head switching signal, which is obtained from a rotational position detector attached to the rotating cylinder, and is normally a 30Hz rectangular wave. For example, when this signal is "H", the rotating head 2 is magnetically The tape 4 is scanned, and the rotary head 3 scans the magnetic tape 4 during the "L" period. Therefore, 1/ at the left end in the diagram
The rotating head 2 scans the magnetic tape 4 for 60 seconds,
Since the scanning locus is 8, the rotary head 2 picks up only the R azimuth signal, resulting in a downward-sloping head output signal as shown in FIG. 3b, which is the signal of recording track _R1 . Similarly, for the next 1/60 second, the rotating head 3 with the azimuth angle L scans the scanning locus 9, so the head output signal has an upward slope to the right, which is the signal of track _L2 . Similarly, R ₃ ,
This becomes the playback output of L ₄ , R ₅ , L ₆ , ... Of the video signals recorded on the magnetic tape 4, this reproduction signal is transmitted from recording tracks L ₁ , R ₂ , L ₃ , R ₄ , L ₅ ,
This indicates that the signal of R ₆ , ... cannot be reproduced. Also, the signal of the played track is always 100
%, but a damping part occurs in one field period (1/60 second), resulting in a poor S/N ratio. If such a signal is recorded on a slave tape, the video signal will have missing parts and noise parts, resulting in a signal that is completely unusable.

As is clear from the above explanation, duplication that reduces the time to 1/2 depends on doubling the tape speed and eliminating video signal dropouts and signal degradation during playback. In the present invention, in order to make this possible, the playback speed of the parent tape is doubled, for example, and the rotational speed of the rotary cylinder 1 to which the rotary head is attached is also doubled, and the parent tape is played back. The recording of the child tape is also carried out by doubling the tape speed and doubling the rotational speed of the rotary cylinder.

Figure 3c shows the head switch signal when the rotating speed of the rotary cylinder is doubled, which is 60 Hz instead of the normal 30 Hz. d shows the head output when both the playback tape speed and the rotating cylinder rotation speed are doubled, and the leftmost 1/
In 120 seconds, the rotary head 2 scans the recording track _R1 without any track deviation, so that the video signal of _R1 can be obtained without attenuation at all. Similarly, in the next 1/120 seconds, the rotary head 3 scans the _L1 track and reproduces the _L1 video signal, and then the _R2 ,
Reproduction is performed in the order of L ₂ , R ₃ , L ₃ , ... In this case, the recording tracks R ₁ , L ₁ , R ₂ ,
The video signal of L ₂ ,... is not lost, and
The output is also reproduced without attenuation, and the time required for reproduction is half that of recording. In other words, twice as much video information is played back within the same amount of time. If the playback signal of the master tape obtained in this way is used as an input signal to a VTR equipped with a child tape, and the VTR also records at double the normal speed of the tape and rotation speed of the rotating cylinder, then
A track pattern that is exactly the same as the track pattern shown in FIG. 2 is recorded on the slave tape, and duplication can be accomplished in half the time. In this case, the relative speed between the magnetic tape and the rotating head is almost doubled, so the frequency of the video signal played from the parent tape is also doubled, but the recording wavelength is the same as when playing back at the normal speed. It is sufficient to improve the frequency characteristics of the head amplifier, etc. In addition,
The control signal that serves as the reference for the VTR's servo circuit is the control signal that is played back from the control track of the parent tape on the playback VTR.
On the recording side, the vertical synchronization signal of the reproduced video signal or the control signal of the parent tape obtained on the reproduction side can be used.

FIG. 4 is a schematic configuration diagram for explaining one embodiment of the present invention. In the figure, a magnetic tape 12 is pulled out from a cassette 11 containing a parent tape, wound around a reproducing cylinder 13, passed through a control head 16, and driven by a capstan 17 and a pinch roller 18, so that the magnetic tape 12 in the cassette 11 is It is taken up on the take-up reel. The cylinder 13 receives a signal from a reference signal generator 24 and an FG (frequency generator) installed inside the cylinder.
The cylinder servo system 23 receives information from the PG (position detector) and rotates at twice the normal speed (60Hz). Capstan 17 is control head 1
The capstan servo system 22 receives the control signal reproduced from the reproducing cylinder 13 and the output of the reference signal generator 24, and controls the tape speed to double the recording speed.
rotating heads 14 and 15 mounted on;
The positional relationship of the magnetic tape 12 is controlled. In this way, the rotation speed of the rotary head and the running speed of the magnetic tape are controlled to be twice as high as when recording, and the signals obtained from the rotary heads 14 and 15 are amplified by the head amplifiers 19 and 20, and the mixer 21 If the signals are added, a continuous reproduced signal is obtained as shown in FIG. 3d. This signal passes through a recording amplifier 40,
Rotating head 2 attached to recording cylinder 27
8 and 29. The magnetic tape 26 of the cassette 25 loaded with the slave tape is driven by a capstan 31 and a pinch roller 32 via a recording cylinder 27 and a control recording head 30.
The recording cylinder 27, like the reproducing cylinder 13, uses a vertical synchronizing signal separated from the reproducing signal by a vertical synchronizing separator 34 and a cylinder servo system 36 to which the outputs of FG and PG provided in the cylinder are input. The rotation speed is controlled to . The capstan 31 receives a signal obtained by dividing the frequency of the vertical synchronization signal by a frequency divider 35, an FG provided in the capstan 31,
Capstan servo system 3 where PG output is input
3, the speed is controlled to twice the normal speed. Frequency divider 3
The output of 5 is supplied to a control recording head 30, and a control signal that maintains a constant relationship with the rotary heads 28, 29 is recorded. As described above, the video signal supplied by the recording amplifier 33 is recorded by the rotary heads 28 and 29 in the same format as the parent tape.

As described above, in this embodiment, the running system of the parent tape and the child tape is controlled to double the speed of the parent tape recording for both the cylinder and the capstan, and the parent tape is in the playback state and the child tape is in the recording state.
Signals are recorded on the child tape in the same recording pattern as on the parent tape, making duplication possible in half the time.

Furthermore, in the present invention, recording of control signals is implemented with the configuration shown in FIG. 5 to simplify the apparatus. This is the vertical sync separator 34 in FIG.
, and the frequency divider 35 is omitted. Since the control signal reproduced by the control head 16 on the reproduction side is amplified by the amplifier 37 and has a differential waveform as shown by waveform a, it is not preferable to record it as it is in the control head on the recording side. Therefore, the waveform shaping circuit 3
8, the waveform is shaped to have an appropriate duty as in normal control signal recording, and the signal is recorded by the control recording head 30 via the amplifier 39. Note that the output of the waveform shaping circuit 38 is transmitted to the capstan servo system 33 and the cylinder servo system 36.
is added to the signal and used as a servo reference signal.
Generally, in order to separate the vertical synchronization signal from the head output signal, it is necessary to demodulate the RF signal that has been FM modulated with the video signal, but in this embodiment, the vertical synchronization separator 34 is not required, so the video signal is Amplifier 40 records the RF signal directly without the need for demodulation
Since recording can be performed by adding the recording head to the recording heads 28 and 29 via the recording head, the apparatus has the advantage of being simple.
Furthermore, since the FM demodulation and FM modulation of the video signal are respectively deleted, there is no performance deterioration due to these circuits, and the signals recorded on the parent tape are recorded on the child tape with almost no deterioration, making high-performance duplication possible. becomes.

In the above embodiment, a method of reducing the duplication time to 1/2 was described, but it goes without saying that the duplication time can be reduced to 1/n by increasing both the tape running speed and the rotational speed of the rotary cylinder by n times. Further, although the above example has been explained in which a VTR and a child VTR are integrated, it is of course possible to provide such a duplication function to a conventional VTR and perform it by arranging two units side by side.

As described in detail above, the present invention controls both the tape running speed and the cylinder rotational speed to n times the normal speed, obtains the playback signal of the parent tape, and transmits that signal to both the tape running speed and the cylinder rotational speed. By controlling the magnetic tape by n times and recording the reproduction signal as an RF signal on the slave tape, the magnetic tape duplication time can be reduced to 1/n, and the effect is very large.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts of an ordinary rotating head type magnetic recording/reproducing device, Figure 2 is a schematic diagram of a tape pattern, and Figures 3a, b, c, and d are relationships between head switching signals and head output signals. FIG. 4 is a schematic configuration diagram for explaining one embodiment of the present invention, and FIG. 5 is a circuit diagram of main parts of another embodiment of the present invention. 1... Rotating cylinder, 2, 3... Rotating head,
4...Magnetic tape, 6...Control track, 11,25...Cassette, 12,26...Magnetic tape, 13,27...Cylinder, 14,1
5, 28, 29... Rotating head, 16, 30...
Control head, 17, 31... Capstan, 18, 32... Pinch roller, 21... Mixer, 22, 33... Capstan servo system, 2
3, 36...Cylinder servo system, 24...Reference signal generator, 34...Vertical synchronization signal separator, 38...
...Waveform shaping circuit.

Claims (1)

[Claims] 1 has a first and a second tape running system, and has a first tape running system.
A recorded tape is run in the second tape running system and an unrecorded tape is run in the second tape running system, and the tape running speed of the first and second tape running systems and the rotation speed of the rotary head are controlled. , the recording speed of the recorded tape is controlled to be n times the recording speed, and the signal reproduced from the first tape running system is recorded on the tape of the second tape running system; The capstan servo system and cylinder servo system that make up the system use the control signal reproduced from the control head of the first tape running system as a reference, and waveform-shape the control signal to drive the second tape running system. 1. A videotape duplicating device configured to supply a control recording head of a videotape system.