JPS6128169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an absolute 180-degree
This invention relates to an angle adjustment method for arranging the device at a position of .

As is well known, a two-head diagonal scanning VTR is equipped with a pair of video heads 1 and 2, as shown in FIGS. 1 and 2, for example.
A rotary disk 3, which is disposed at an absolute 180° position, is inserted into a cylinder 5 having a slit 4, and each of the video heads 1 and 2 has a gap 1a and 2a thereof which is arranged at an absolute 180° position. The cylinder 5 is rotated in the direction of the arrow X in the figure while being projected to the outside of the cylinder 5 through the cylinder 5. Further, the magnetic tape 6 is mounted on the cylinder 5 in a convex shape with an appropriate inclination by tape guides 7 and 8, and is arranged in a convex manner with an appropriate inclination in the direction of rotation of each of the video heads 1 and 2 (direction of arrow X). It runs in the opposite direction (arrow Y direction in the figure). Then, each time the video heads 1 and 2 come into contact with the magnetic tape 6, a video signal representing one field of screen is sequentially recorded on the magnetic tape 6 as one diagonal track as shown in FIG. be done. In FIG. 3, A indicates a track recorded by the first video head 1, and B indicates a track recorded by the second video head 2. In FIG. Furthermore, by sequentially tracing each of the tracks A and B on which video signals are recorded as described above with each video head 1 and 2,
It is obtained from video heads 1 and 2 above.

By the way, each of the above video heads 1 and 2 is absolutely
If the track A is located at a position deviating from the 180° position, each track A on which the video signal was recorded as described above,
When tracing B in each video head 1 and 2, track A may be traced in the second video head 2 and track B may be traced in the first video head 1, or in some other way.
If each track of a magnetic tape recorded on a VTR is traced using each of the video heads 1 and 2 mentioned above, it will not be possible to trace correctly, so the track will be played back using the reproduced video signals obtained from each video head 1 and 2. It is known that distortion occurs in the images that are captured.

Conventionally, the above-mentioned drawbacks have been solved by arranging each video head at an absolute 180° position according to the angle adjustment method described below. Figure 3 shows the conventional angle adjustment method.
This will be explained using FIGS. 4 and 5.

That is, a video signal that displays a vertical line (indicated by a broken line in FIG. 4) on the screen of the CRT 7 is recorded on a magnetic tape by the first video head 1 on track A, and is recorded on the track A by the second video head 2. track B
For example, by tracing track A with the second video head 2 and tracing track B with the first video head 1, when obtaining a reproduced video signal, As shown in FIG.
If there is a deviation of α° (angular deviation) from 180°, the amount of distortion X of the reproduced image (shown by the solid line in Figure 4) obtained on the screen of the CRT7 will be determined by the deviation of the above-mentioned placement position. Since it corresponds to α゜, the above quantity X is 0
Recording, playback, each video head 1, 2 so that
Repeatedly adjust the installation position of one side.

By the way, in the case of a VTR with azimuth, the sixth
As shown in the figure, since the azimuths of the gaps 11a and 12a of the first and second video heads 11 and 12 are different, the track recorded by one video head is traced by the other video head to produce a reproduced video signal. Therefore, the conventional angle adjustment method as described above cannot be applied, and the absolute 180
It was not possible to arrange each video head 11, 12 at a position of .degree.

Therefore, the present invention provides an angle division adjustment method that allows each video head to be placed at an absolute 180° position even in an azimuthal VTR, and allows each video head to trace each track correctly. It is something to do.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIGS. 7-, 7-, 7-, and 7- are drawings showing an example of the structure of the first and second video heads 21, 22 used in carrying out the present invention.
In the figure, first and second video heads 2
1 and 22 are trapezoidal columnar first cores 23 and 24.
through each second and third core 25, 26, 2
7 and 28 are butted together. here,
Each of the above second and third cores 25, 26, 2
7, 28 have notches 29, 30, 31, 32, respectively.
are provided, and each of the above-mentioned notches 29, 30, 3
Each window portion 33, 34, 3 formed in the 1, 32 portion
Coils 37 and 38 are wound around coils 5 and 36, respectively. The first and second video heads 21 and 22 are formed by matching the first cores 23 and 24 with the second and third cores 25, 26, 27, and 28, respectively. 2 gap 37,3
It has a double gap structure having an 8, third and fourth gap 39, 40, respectively. Here, the first gap 37 formed by the first core 23 and the second core 25 in the first video head 21 is the same as the first gap 37 formed by the first core 24 and the third core in the second video head 22. The second gap 38, which is formed by the first core 23 and the third core 27 in the first video head 21, has an azimuth equal to the fourth gap 40 formed by the first video head 21. It has an azimuth equal to the third gap 39 formed by the first core 24 and the second core 26 in the second video head 22. Furthermore, the distance l _A between the first gap 37 and the second gap 38 in the first video head 21 is the same as that in the second video head 21.
It is equal to the distance l _B between the third gap 39 and the fourth gap 40 in No. 2.

Generally, it is necessary to form a gap of 1μ or less in a video head, and the manufacturing technology has improved greatly in recent years, making it possible to manufacture it with extremely high dimensional accuracy. Therefore, the double gap structure used in the present invention is It is also possible to manufacture the spacings l _A and l _B between each gap in the video head to be equal with high precision.

Therefore, if a video signal is recorded on a magnetic tape using a VTR in which the first and second video heads 21 and 22 having the structure described above are arranged at relative positions of about 180 degrees on a rotating disk (not shown), Track A on the magnetic tape 46 is connected to the first video head 21.
Accordingly, video signals are recorded on track B by the second video head 22 with different azimuths (see FIG. 8).

Here, the video signals are recorded on each of the tracks A and B by the first and second video heads 21,
Of the 22 gaps 37, 38, 39, and 40, the scanning is performed at a gap that scans the magnetic tape surface with a time delay. That is, for example, if we consider that the above-mentioned Figures 7-,- are expanded along the circumference of the rotary disk and displayed flatly, the arrow Z in the figure
If the magnetic tape surface is to be scanned in the first
and in the second video head 21, 22,
First, the first gap 37 and the third gap 3
After the video signal is recorded at 9, the recording of the video signal is played back at the second gap 38 and the fourth gap 40, and finally the video signal is played back at the second gap 38 and the fourth gap 40. The video signal is thus recorded.

In the present invention, the track A of the magnetic tape 46 on which the video signal has been recorded in the second gap 38 of the first video head 21 as described above is transferred to the third gap of the second video head 22. 39 and the second video head 22
By tracing the track B of the magnetic tape 46 on which the video signal has been recorded in the fourth gap 40 of the magnetic tape 46 in the first gap 37 of the first video head 21, the arrangement of each video head 21, 22 can be determined. Detects the angle deviation of the installed position from the absolute 180° position.

That is, in an azimuthal VTR using the conventional video heads 11 and 12 as shown in FIG. However, in the present invention, the first and second video heads 21 and 22, which have the second and fourth gap 38 and 40 of different azimuth, respectively have the other gap 40,
The first and third gap 37, 39 with azimuth equal to azimuth 38 are equally spaced l _A , l _B
Therefore, the third gap of the second video head 22 has an azimuth equal to the azimuth of the second gap 38 of the first video head 21 that recorded the video signal on the track A. 39, the second video head 22 traces the track A and records the video signal on the track B.
A reproduced video signal can be obtained by tracing with the first gap 37 of the first video head 21 having an azimuth equal to the azimuth of the fourth gap 40 of the first video head 21 .

Therefore, it becomes possible to perform the angle division adjustment according to the same procedure as in the conventional example described above. That is, if the method of the present invention is explained using the above-mentioned FIG. 4, FIG. 5, and FIG. is recorded on track A of the magnetic tape 46 at the second gap 38 of the first video head 21, and recorded on track B at the fourth gap 40 of the second video head 22 to obtain a reproduced video signal. At the same time, track A is transferred to the third video head of the second video head 22.
Trace with gap 39 and move track B to the 1st position.
By tracing with the first gap 37 of the video head 21, for example, as shown in FIG.
If the installation position is deviated by α° from the absolute 180°, the amount of distortion X of the reproduced image (shown by the solid line in Figure 4) obtained on the screen of the CRT7 will be the same as that of the above installation position. Since it is obtained corresponding to the angle division deviation α゜,
By sequentially repeating recording, playback, and adjustment of the installation position of each video head 21, 22 so that the above amount X becomes 0, the angle division can be adjusted. It can be placed in the position of ゜.

Note that four gaps are required to implement the present invention, and if the above gaps are not arranged on the same plane, errors in the magnetic tape path system peculiar to azimuthal VTRs may occur, as shown in Figure 9. This causes an error in the angle division adjustment, but in the present invention, each video head is constructed with a double gap structure.
Since each gap is integrally formed,
Rather than adjusting the relative positions of the four gaps separately, tracking is performed when tracing each track on the magnetic tape.
The apparent angular deviation can be ignored simply by adjusting the installation positions of the video heads so that they are placed on the same plane.

Here, in the above-mentioned FIG. 9, the above-mentioned first
The track A on which the video signal was recorded in the second gap 38 of the video head 21 is traced by the third gap 39 of the second video head 22 having a tracking deviation D, and This shows a state where an apparent angular deviation X' has occurred.

Further, since the magnetic tape on which the video signal is recorded by the azimuth-equipped VTR adjusted in accordance with the present invention as described above has tracks free from angular deviation, the above-mentioned magnetic tape A VTR with azimuth, which is equipped with each video head as shown in Fig. 6 above, using
By adjusting the placement position of each of the above video heads so as to obtain a reproduced image without distortion, each of the above video heads can be placed at an absolute 180° position.

As described above, according to the present invention, a VTR with azimuth
It is possible to adjust the angle of the video head by a simple procedure, ignoring the apparent angle deviation due to errors in the magnetic tape path system that is specific to the magnetic tape path system. It can be placed in the position of Therefore, the intended purpose can be fully achieved.

[Brief explanation of the drawing]

1 and 2 are a plan view and a front view showing the structure of a cylinder section of a general two-head type oblique scanning VTR. FIG. 3 is a diagram showing a recording track pattern on a magnetic tape in the oblique scanning type VTR shown in FIGS. 1 and 2 above. 4 and 5 are diagrams for explaining the conventional angle dividing method and the angle dividing method according to the present invention.
2 is a drawing showing a display pattern on a CRT screen and the arrangement positional relationship of each video head. 6th
The figure is a front view showing the general structure of each video head used in an azimuthal VTR. FIG. 7 is a diagram showing the structure of each video head used in the method of the present invention. FIG. 8 is a drawing showing a recording track pattern of a magnetic tape in an azimuthal VTR. Figure 9 shows azimuth
2 is a diagram for explaining an apparent angle deviation due to an error in a magnetic tape path system in a VTR. 21, 22... Video head with double gap structure, 37, 38, 39, 40... Gap of video head, 46... Magnetic tape, X... Amount of distortion, α... Angular deviation.

Claims (1)

[Claims] 1 A video head with a double gap structure is used, in which a pair of video heads each having a different azimuth are integrally formed with gaps having an azimuth equal to the azimuth of the other gap at equal intervals. The amount of distortion in the image reproduced from the reproduced video signal obtained by tracing the track of the magnetic tape on which the signal was recorded with the other video head is detected, and each video head is adjusted so that the distortion becomes zero. With azimuth feature that the installation position can be adjusted
How to adjust the angle of the video head in a VTR.