JPS5845227B2 - Eizou Shingo no Kirokuhouhou - Google Patents

Description

[Detailed description of the invention] For example, a video signal is recorded on a tape by a rotating head,
Further, when reproducing this, the following method can be considered as a method that can significantly increase the recording density and does not require tracking servo during reproduction.

FIG. 1 shows an example of a rotating magnetic head device used in this method, in which two rotating magnetic heads 1A and 1B are mounted on a rotating body.
They are installed with angular spacings that differ from each other by a slight angle α relative to 1800 mm.

The head 1A is used for both recording and reproduction, and the head 1B is used only for reproduction.

Then, the magnetic tape 2 is placed against the tape guide drum 3.
It runs diagonally along the α-shape over its entire circumference, that is, over a 3600 angular range.

Then, the heads 1A and 1B are rotated at a rotational speed such that they make one revolution in a time slightly shorter or slightly longer than two fields of the video signal to be recorded, and the video signals to be recorded are supplied to the head 1A. In the above, two vertical synchronization signals are recorded for each track, and the video signal is recorded on the tape so that the recording position of the vertical synchronization signal and the recording position of the horizontal synchronization signal are aligned in the direction of the gap between one head. Record on 2.

For example, when the tape 2 is run in the direction shown by arrow 4 and the heads 1A and 1B are rotated in the direction shown by arrow 5,
In other words, if the moving force direction of the tape 2 and the heads 1A and 1B is the same, and if the heads 1 and 1B are rotated at a rotational speed such that 2 fields make one revolution, there will be a space on the tape 2 as shown in Fig. 2. Track TA by one head as shown.

TB, Tc, etc. are formed sequentially, and each track records signals for two fields.Therefore, two vertical synchronizing signals are recorded on each track, and this The recording positions PV of vertical synchronization signals are arranged in the longitudinal direction of the tape 2, and in the extending direction of each track,
When the horizontal period of the video signal to be recorded is TH, kT
They are sequentially shifted by a distance corresponding to H.

In this case, heads 1A and 1B are set to 2 fields kT.
Rotate at a rotation speed of 1 rotation at H.

In this way, as shown in FIG. 3, the tracks TA, TB, Tc, . . .
. As the signals are recorded, the recording positions pv of the vertical synchronizing signals are arranged in a direction perpendicular to the extending direction of each track, that is, in the width direction of the gap between one head, and are further enlarged in FIG. As shown, in adjacent tracks, the recording positions PVO of vertical synchronizing signals of odd fields and the recording positions PVE of vertical synchronizing signals of open fields overlap each other in the track extension direction, so the recording position PH of horizontal synchronizing signals also overlaps with each other in the track extension direction. Similarly, they are arranged in a direction perpendicular to the extending direction of each track.

For example, the video signal to be recorded is an NTSC signal,
In the case of k=4, it is rotated at a rotational speed that makes one rotation at 521TH.

The angle α mentioned above is n20, 1, 2 . ......, select the angle corresponding to (n+1/2)TH, and n
For example, you can set it to zero.

Therefore, when rotating the heads 1A and 1B at a rotational speed of 521TH rotation, the following equation is used.

If the moving direction of the tape 2 and the heads 1A and 1B is opposite, the heads 1 and 1B are rotated at a rotational speed of 2 fields and 1 rotation at 1 kTH. A guard band is not formed between each track, and each track is sequentially formed at a pitch smaller than the gap width of one head and 1B.

In addition, when recording a video signal by amplitude modulation or phase modulation, as shown in FIG. 5, its carrier wave J.

so that the phases of adjacent tracks are aligned at each position in the direction of extension.

During playback, heads 1 and 1B are rotated at the same rotational speed as during recording, and the reproduction signals from heads 1 and 1B are switched, starting from the vicinity of the recording position of the single vertical synchronization signal on each track. Continuously reproduce and output only the reproduced signal from the portion close to the recording position of the other vertical synchronization signal, that is, for example, only the reproduced signal from the vicinity of the rectangle ABCD shown with diagonal lines in FIG. 6. Take it out as a signal.

- According to the method described in E, during playback, 2
Even when scanning across more than one track, the head
This means that the signal portions of the horizontal section at the same position counting from the vertical synchronization signal of each track and at the same time after the horizontal synchronization signal are played back at the same time.
Since the signal contents of four adjacent frames are not so far apart, no particular inconvenience occurs, and no synchronization disturbance occurs in the reproduced signal.

Therefore, no tracking servo is particularly required during playback.

In addition, good slow or still image signals can be easily obtained.

Moreover, since there is no problem when the head scans over two or more tracks in close proximity during playback, there is no need to provide a guard band during recording, and each track is scanned at a pitch smaller than the gap width of the head. The tracks can be formed sequentially, thus significantly increasing the recording density.

By the way, even if one rotating magnetic head is rotated at a rotational speed of, for example, 521TH, exactly once using the method described above, the tape speed will change slightly, and therefore the track pitch will change slightly. (in this case, the above-mentioned value of k changes), or when the tape expands or contracts, the recording position pv of the vertical synchronization signal
And the recording position PH of the horizontal synchronization signal is no longer aligned accurately in the direction orthogonal to the extension direction of each track as described above, resulting in synchronization disturbance during playback, or a signal with horizontally shifted content as a playback signal. An inconvenience occurs in that a composite output of 1 is obtained.

In view of these points, the present invention is designed to ensure that the above-mentioned recording pattern is formed reliably and accurately.Hereinafter, an example of the method of the present invention will be explained with reference to FIG. 7 and subsequent figures.

In FIG. 7, reference numeral 6 denotes a motor that drives the head 1 and 1B, and a frequency generator 7 with, for example, 521 teeth is attached to its rotating shaft, and a signal from this is supplied to a phase comparator circuit 8. , the video signal to be recorded from the input terminal 9 is supplied to the horizontal synchronization signal separation circuit 10 to extract the horizontal synchronization signal, which is supplied to the phase comparison circuit 8, and the comparison error signal from the circuit 8 is passed through the adder 11. , ζ is supplied to the motor 6 through the amplifier 12, and the motor 6 and therefore the heads 1A and 1B are
is rotated at a constant speed, such as one rotation at 521TH.

In this state, the video signal to be recorded from the input terminal 9 is supplied to one head through the recording circuit 13 and the recording amplifier 14.

In this case, a switching circuit 15 is provided, and the horizontal synchronizing signal from the actual circuit 10 is supplied to the switching signal forming circuit 16, so that every other horizontal section of the video signal SR (FIG. 8A) to be recorded is A switching signal Sc (FIG. 8B) whose state is inverted between a predetermined period TA of the horizontal flyback section in which the horizontal synchronizing signal H□ is inserted and other periods is obtained, and this switching signal Sc is is supplied to the switching circuit 15, and during a predetermined period TA, the circuit 15
is switched to the state opposite to the state shown in the figure, the head 1A is put into the playback state, and the playback signal from one head is taken out through the circuit 15. During the other period, the circuit 15 is switched to the state shown in the figure, and the head 1A is put into the playback state. is placed in a recording state, and the signal SR is recorded onto the tape 2 by one head.

The reproduction signal taken out through the switching circuit 15 is supplied to the phase comparison circuit 19 through the reproduction amplifier 17 and the reproduction circuit 18, and the horizontal synchronization signal in the video signal to be recorded from the circuit 10 is supplied to the phase comparison circuit 19. The comparison error signal from the circuit 19 is supplied to the motor 6 through the adder 11 and the amplifier 12 to control the rotational phase of the motor 6 and therefore of the head 1 and 1B.

Therefore, as shown in Figure 8, after every other horizontal synchronizing signal is recorded on track T1 for the first frame at position H1, the next frame's worth is recorded on track T2.
Since one frame is composed of an odd number of horizontal sections, the video signal SR to be recorded at this time will be recorded near the point in time when one head scans the position H1 of the track T1. every other horizontal synchronization signal HRA of is not recorded on track T2, the remaining every other horizontal synchronization signal HRB is recorded at position H2, and every other horizontal synchronization signal HRA of force not recorded; Truck T
Since the rotational phases of the heads 1A and 1B are controlled by the signal from the phase comparator circuit 19 so that the phases of the horizontal synchronizing signal Hp (FIG. 8C) reproduced from the position H1 of 1- Every other horizontal synchronous signal on the lower rack 2 +3'H
The recording position H2 of RB is located exactly in the middle of the recording positions H1 of every other horizontal synchronizing signal on the previous track T1.

Similarly, when the next frame is recorded on track T3, the recording position H3 of every other horizontal synchronization signal on this 1-rack lower 3 is the same as every other horizontal synchronization signal on the previous track T1. Just in the middle of the recording position H2 of the horizontal synchronization signal, therefore every other horizontal synchronization signal recording position H1 on the track T1
In this way, tracks are formed one after another with a pitch smaller than that in the air gap of one head, and the horizontal alignment of each rack is The recording positions of the synchronizing signals are accurately aligned in the direction perpendicular to the direction of extension of each track, that is, in the width direction of the gap between one head.

Therefore, the recording positions of the vertical synchronization signals are also accurately aligned in the same direction.

In addition, since the recording position of the vertical synchronization signal and the recording position of the horizontal synchronization signal are aligned accurately in the width direction of the gap of the head 1A, when amplitude modulating or phase modulating the video signal during recording, Its carrier frequency is 30 Hz
As explained in FIG. 5, by choosing an integer multiple of J.

The phase of each track is precisely aligned at each position in the direction of the extension force.

As described above, according to the method of the present invention, a video signal can be recorded by forming a very special recording pattern reliably and accurately with a simple configuration.

In addition, in one horizontal section for every horizontal section of 3 or more,
During a predetermined period of the horizontal retrace section in which the horizontal synchronization signal is inserted, the head 1A is placed in an endogenous state to reproduce the horizontal synchronization signal from the previous track, and the phase of this signal with the horizontal synchronization signal in the video signal to be recorded is determined. The rotation of the head 1A may be controlled using the comparison error signal.

Furthermore, instead of using the horizontal synchronizing signal as the phase information signal for alignment, an appropriate signal inserted into the horizontal retrace interval at a constant interval relative to the horizontal synchronizing signal may be used.

Further, instead of controlling the rotation of the rotary magnetic heads 1A and 1B, the running of the tape may be controlled.

Further, the configuration of the rotary magnetic head device, such as the number of rotary magnetic heads and the angle of tape winding, and the accompanying rotational speed of the rotary magnetic head can be changed in various ways other than those described above.

Furthermore, the present invention is applicable to cases in which recording is performed on a single rectangular magnetic sheet by a rotating magnetic head in a pattern similar to the pattern in rectangular ABCD shown in FIG. It can also be applied to recording by forming magnetic tracks in the form of shapes.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an example of a rotary magnetic head device used in the present invention, FIGS. 2 to 6 are illustrations showing recording patterns on a tape for explanation, and FIG. FIG. 8 is a system diagram showing the overall configuration of an example. 1A and 1B are rotating magnetic heads, 2 is a magnetic tape, 3 is a tape guide drum, 6 is a motor, 7 is a frequency generator, 8
and 19 is a phase comparator circuit, 9 is a video signal input terminal, and 10 is a phase comparison circuit;
13 is a recording circuit, 15 is a switching circuit, 16 is a switching signal forming circuit, and 18 is a reproducing circuit.

Claims (1)

[Claims] 1. When recording a video signal by sequentially forming tracks with a pitch smaller than the gap width of the rotating head, when recording the video signal on the first track, a predetermined horizontal section of the video signal to be recorded is recorded. When recording a reference signal on a track subsequent to the first track, the horizontal sections on which the reference signal is recorded are not adjacent to each other between adjacent tracks, and the rotating head is scanned. In a predetermined section including the reference signal section of the predetermined horizontal section into which the reference signal of the track recorded before the track recorded is inserted, the rotary head is put into the playback state, and in other periods, the rotary head is turned on. into a recording state, reproduce the reference signal from the previously formed track in the predetermined section, compare the phase of the reproduced reference signal with the reference signal in the video signal to be recorded, and compare the A method for recording a video signal, wherein the rotation of the rotary head or the running of the recording medium is controlled by an error signal.