JPH0197077A - Dubbing system - Google Patents

Abstract

PURPOSE:To attain satisfactory dubbing by means of a miniature device in which the rotary radius of a rotary head is minimized without converting a time base by executing reproduction with a prescribed period shorter than one field at every field period and recording a reproduced signal with the same prescribed period as that at the time of reproduction at every field period. CONSTITUTION:The rotary heads are arranged so that they record (reproduce) video signals for one field while they respectively rotate 300 deg.. At the time of reproduction, the outputs of the rotary heads are alternately outputted in a change over switch 11 at every field period. A reproduced video signal processing circuit 12 processes the video signals which are outputted from the switch 11 and which have been time base-compressed, and outputs them as dubbing signals. A time base expanding circuit 13 time base-expands the video signals which the processing circuit 12 outputs, and outputs them to a terminal 14. At the time of dubbing, the dubbing signals from the processing circuit 12 are inputted from a terminal 21 to a switch 22, and are supplied to the heads through a recording video signal processing circuit 23 and a switch 25. For using the heads only for recording, the switch 22 is connected to terminals B or C.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a dubbing system, particularly for dubbing signals on a recording medium in which each track has one field of video signal or a large number of recorded tracks. Regarding the system.

<Prior Art> A home-use helical scan video tape recorder (VT
A dubbing system using this type of VTR will be described below.

Generally, a so-called two-hedral helical scan type of home VTR is known. Figure 5 shows this type of VT
It is a diagram showing the arrangement of R heads. In FIG. 5, l is a magnetic tape and 2a.

2b is a tape guide for winding the tape l around the outer periphery of the rotating tram 3 over an angle range of 1806 or more.

+1A and -B are rotating heads respectively attached to the rotating drum 3 with a phase difference of 180' from each other, and have different azimuth angles. As is well known, the heads HA and 8B record and reproduce one field of video signals during 1806 rotations.

In this type of VTR, the track length of one field's worth of video signals is predetermined in the standard, and accordingly the diameter of the rotating drum 3 is necessarily determined. Therefore, the diameter of this drum cannot be made smaller, which hinders the reduction in size and weight of VTRs.

Therefore, the following VTRs have been proposed and implemented as recording-only machines in which the drum diameter can be reduced. FIG. 2 is a diagram showing the head arrangement in a conventional VTR having a small-diameter drum and relating to the dubbing system of the present invention. In the figure, Ha and Hb are rotary heads having different azimuth angles, and rotate once during one field period of the video signal. Tape l is 300 for drum 4
It is wound over an angular range of more than
a, )lb records one field of video signals during each 300@ rotation. That is, a video signal for one field is recorded in a period shorter than the original period of one field of the video signal.

Therefore, the video signal recorded by this type of VTR is N
, T, S When assuming a C signal, it is not a normal NTSC signal, that is, a signal with a vertical scanning frequency (fv) of 60 Hz and a horizontal scanning frequency (fH) of 15.75 KHz (fv
or 60Hz, fH or 15.75 x s” = ) 1
Must be 8-9 KHz.

In other words, the video signal recorded by this type of VTR must be a normal television signal time-axis compressed to 5/6 in units of fields or a signal obtained from a dedicated camera.

The above-mentioned dedicated video camera scans a screen with an aspect ratio of 9:10 (indicated by the dotted line Y in Figure 3).
A screen with an aspect ratio of 3:4, indicated by a solid line X in the figure, is output as an effective screen within a 5/6 field period, and is recorded by heads Ha and Hb.

The timing of this recording will be explained using the timing chart of FIG. 4. During the period indicated by T in the figure, a video camera (not shown) scans seven screens with an aspect ratio of 9:10, and generates a video signal consisting of 315 consecutive horizontal scans as shown in Figure 4(a). obtain.

However, since the actual traces of (Head) la and Hb on tape 1 are 5/6 of them within each field period, 262.5 horizontal scans of the traces are shown in Figure 4 (
As shown in b), the video signal is taken out and recorded on a magnetic tape as a video signal with an aspect ratio of 3:4. At this time het H
Since a and Hb are traced alternately on the magnetic tape, the second
The VTR with the head arrangement shown in the figure can perform recording similar to the VTR with the head arrangement shown in FIG. However, since it is necessary to provide a slight phase difference between the heads Ha and Hb at this time, it is necessary to appropriately delay the video signal of the first field or the second field.

If video signals are recorded as described above with the head arrangement as shown in FIG. 2, the drum diameter can be reduced to the VTR 315 shown in FIG. 6.

By the way, when a recorded video signal is reproduced in a VTR having a head arrangement as shown in FIG. 2, the reproduced video signal does not exist for 176 periods for each rotation of the head. Furthermore, since the horizontal scanning frequency fH is different from that of a normal television signal, it cannot be displayed directly on a television receiver or the like.

Therefore, Japanese Patent Application Laid-Open No. 19372/1983 discloses a configuration that enables reproduction of video signals using a variable delay line. In the VTR disclosed in this publication, the playback video signal obtained in the 5/6 field period of the 1 field period (Fig. 9 (b)
) with a reproduced RF waveform as shown in ) is expanded on the time axis using a variable delay line to obtain a continuous reproduced video signal.

Similarly, it is also possible to extend the time axis to 5/6 by using a so-called field memory and taking one field's worth of video signals as one unit.
-82937 is also disclosed.

<Problem to be solved by the invention> By the way, when dubbing is generally performed using two VTRs, is it necessary to use a signal format that conforms to standard television signals rather than transmitting signals between the two VTRs? be. This is because when dubbing is performed between two VTRs, the vertical synchronization signal of the video signal being dubbed is used to synchronize the rotational phases of the heads of both VTRs.

Therefore, a small VT with a head arrangement as shown in FIG.
When dubbing is performed using two VTRs to construct a compact dubbing system, the reproduction signal of one VTR is time-compressed and recorded on the other VTR. Therefore, a variable delay line with a 0 to 1/6 field period or a memory capable of storing one field's worth of video signals, as well as control circuits for these, are required in both the playback circuit and the recording circuit. Even if the system has been made smaller as a mechanism, the circuitry is expensive and requires a large-scale circuit, so the overall goal of making the system smaller and lower in price has never been achieved.

In addition, since the reproduced video signal is once recorded via a variable delay line and field memory twice, there is considerable signal deterioration while passing through these, which also has a negative effect on the signal being dubbed. I'll give it away.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a dubbing system that is small, inexpensive, and capable of performing good dubbing.

<Means for Solving the Problems> For the above purpose, in the dubbing system according to the present invention, a video signal for one field is recorded on each track from a first recording medium formed with a large number of tracks. In the system for dubbing a video signal onto a recording medium according to No. 7, tracks on the first recording medium are reproduced one track at a time for every l field period for a predetermined period shorter than one field period, and the reproduced signal is The structure is such that recording is performed on the second recording medium while forming a track in the predetermined period for each field period without converting the time axis.

<Operation> With the configuration as described above, it is possible to perform good dubbing using a small device with a small rotation radius of the rotary head without performing time axis conversion during dubbing.

<Example> A dubbing system as an example of the present invention will be described below with reference to FIG.

In Fig. 1, the configuration of the playback device will be explained first.
, Hb are rotary heads arranged as shown in FIG. 2, and the outputs of these rotary heads are alternately outputted every 1 field period by a head changeover switch 11. As is clear from the above description, during the output of the switch 11, the period in which the video signal exists is the period of 5/6 of the field period, and the frequency of the reproduced signal is the 5th field period.
One of the signals reproduced by a VTR with a head arrangement as shown in the figure.
．． That's twice as much. The reproduced video signal processing circuit 12 frequency-converts the reproduced luminance signal obtained by FM demodulating the FM-modulated luminance signal in the video signal outputted from the switch 11 and the carrier color signal subjected to low frequency conversion to the original band. The obtained reproduced carrier color signal is mixed and outputted as a reconstructed video signal. This circuit 1
The operating frequency of 2 is the VTR with the head arrangement as shown in Figure 5.
Needless to say, the operating frequency is 1.2 times that of .

Reference numeral 13 denotes a time axis expansion circuit which expands the time axis of the video signal output from the reproduced video signal processing circuit 12 to 615 fields in units of fields and outputs the expanded video signal, which is constructed of a variable delay line or a field memory as described above. 14 is time axis expansion circuit 1
This is a terminal for outputting to an external monitor or the like as a video signal in a signal format conforming to the standard television signal outputted from 3. However, if there is no need to monitor the video signal during dubbing with an external monitor etc., this time expansion circuit 13
And the output terminal 14 is unnecessary.

The video signal output from the reproduced video signal processing circuit 12 is supplied to the subsequent recording device via the other terminal 15. The output of the circuit 12 is also supplied to a sync separation circuit 16, and the vertical sync signal separated by the separation circuit 16 is supplied to a drum control circuit 17. The drum control circuit 17 synchronizes the rotation of the rotary head drum 4 holding the heads Ha, l(b) with this vertical synchronization signal. Here, the output of the circuit 12 is such that the video signal is time-axis compressed to 5/6 for each l field. However, since the vertical synchronization signal is obtained once in the l-field period when the head Ha,i(b) is at a predetermined rotational phase, it can be used to control the rotational phase of the drum 4.

Next, the configuration of the recording device will be explained. The dubbing video signal outputted from the terminal 15 is inputted to the recording device from the terminal 21. The switch 22 is connected to the A terminal during dubbing, and the dubbing video signal input from the terminal 21 is sent to the recording video signal processing circuit 2 via the switch 22.
3 and the synchronization separation circuit 24.

The recording video signal processing circuit 23 performs FM modulation on the luminance signal in the 5/6 time-axis compressed video signal, frequency-converts the carrier color signal to the lower frequency side of the FM-modulated luminance signal obtained in this way, and These are mixed and output. The output of the circuit 23 is supplied to the heads Ha'', )lb' via a switch 25, and is recorded on a magnetic recording medium (tape) (not shown). A recording signal is supplied to the head H” and Hb′.
a'' and Hb' each record one field worth of video signals as one tree track during a 5/6 field period.

In addition, the head is "Ha".

Hb" has the same head arrangement as heads Ha and Hb,
The diameters of drum 4 and drum 4' are the same.

Further, one operating frequency of the recording video signal processing circuit 23 is the fifth
This is 1.2 times that of the VTR with the head arrangement shown in the figure.

Similar to the circuit 16, a vertical synchronization signal is obtained from the synchronization separation circuit 24 every one field period.

A drum control circuit 26 controls the rotation of the drum 4' so that the rotations of the heads Ha'' and Hb' are synchronized with this vertical synchronization signal.

When this recording apparatus is used only for recording, not for dubbing, the switch 22 is connected to terminal B or C. 31 is an overscan camera that scans a screen with an aspect ratio of 9:10 with 315 horizontal scanning lines every l field period, and outputs the effective screen as 262.5 lines in 5/6 field period, as mentioned above. is supplied to the recording signal processing circuit 23 via the terminal B of the switch 22, and is similarly supplied to the head Ha'.

11b'.

Further, 32 is an external input terminal, into which a video signal in a signal format conforming to a standard television signal is inputted, for example, from a television tuner or the like. Since this input signal cannot be recorded in its original signal form, the time axis is compressed to 5/6 in units of one field by the time axis compression circuit 33, and the switch 22
0 time axis compression circuit 3 similarly recorded via terminal C of
Similarly to the time expansion circuit 13, the circuit 3 can be configured using a variable delay line with a 0 to ⅙ field period or a field memory. However, if used only for dubbing, camera 31,
The terminal 32, time compression circuit 33, and switch 22 are not required.

According to the above-mentioned system, the signal to be dubbed is not subjected to time-base conversion, so that signal deterioration is reduced.

Furthermore, when used for dubbing, field memories, variable delay lines, etc. are not required, and a compact and low-cost dubbing system can be obtained.

<Effects of the Invention> As described above, according to the present invention, a small, low-cost dubbing system with little signal deterioration can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of a dubbing system according to an embodiment of the present invention, Fig. 2 is a diagram showing a head configuration of a conventional VTR according to the present invention, and Fig. 3 is a diagram showing a VTR with the head arrangement shown in Fig. 2. Figure 4 is a timing chart for recording in a VTR with the head arrangement shown in Figure 2. Figure 5 is a diagram showing the head arrangement of a conventional general VTR. It is. In the figure, Ha, Hb, Ha', and Hb' are rotating heads, respectively. 12 is a reproduction video signal processing circuit, 16 and 24 are synchronous separation circuits, 17 and 26 are drum control circuits, and 23 is a reproduction video signal processing circuit.

Claims (1)

[Claims] A system for dubbing a video signal from a first recording medium to a second recording medium, the first recording medium having a large number of tracks each recording one field of video signals, wherein the first recording medium The upper track is reproduced one track at a time for each field period for a predetermined period shorter than one field period, and the reproduced signal is recorded on the second recording medium for the predetermined period for each field period without converting the time axis of the reproduced signal. A dubbing system that records while forming a track.