JPH0481245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotary head device in a helical scan type video tape recorder (hereinafter abbreviated as VTR).

Conventional configuration and its problems In a helical scan VTR, one field is recorded on one track, and each field is recorded using a magnetic head with a different azimuth angle. Therefore, video signal recording is synchronized using a vertical synchronization signal, and the control signal and video signal are recorded on the magnetic tape. During playback, synchronization is achieved using the control signal, and the recording track is recorded using a head with the same azimuth as the recording head. By tracing, a reproduced image without noise is obtained.

However, during special playback such as static, low-speed, and high-speed playback, noise bars appear on the screen because the playback head traces across multiple recording tracks.

Recently, a playback head has been mounted on a piezoelectric drive element with a laminated structure made of voltage porcelain plates, and an electric field corresponding to the shift is applied to the piezoelectric drive element so that the head does not shift from the recording track during special playback. There are VTRs that can be modified to produce a noise-free playback screen.

However, with conventional VTRs that use piezoelectric drive elements, the mounting accuracy on the rotating cylinder is poor, and the position of the head on the piezoelectric drive element changes over time. This head could not be used for recording because it exceeded the standard value, so another magnetic head was fixed to the rotating cylinder and used for recording.

Recently, FM audio has been put on the market, and the optimal head width has been selected for recording and playback of video signals in standard mode and long-time mode. Therefore, the number of heads mounted on a rotating cylinder has increased, and the number of rotary transformers serving as input/output means for the heads has also increased. Therefore, if separate heads were used for recording video signals and special playback, the number of heads would increase, the structure of the rotating cylinder would become complicated, and the price would increase, which became a problem.

OBJECTS OF THE INVENTION An object of the present invention is to provide a rotary cylinder device with a simple structure and an optimal system with a small number of heads, in which a magnetic head for both recording and reproducing video signals is mounted on a piezoelectric drive element.

Structure of the Invention According to the present invention, a magnetic head for video signals is mounted on a bonded piezoelectric drive element and fixed to a rotating cylinder, and a height detecting magnetic head having a head width equal to that of the head is mounted on the rotating cylinder. is fixed, and before the video signal is recorded by the magnetic head mounted on the piezoelectric drive element, the track recorded by the height detection magnetic head is reproduced by the head on the drive element. This makes it possible to adjust the head height.

In such a configuration, the height of the video signal head can be adjusted by simply adding one input/output section to the head. In addition, since a video signal recording/reproducing head can be mounted on the piezoelectric drive element, the rotary cylinder device has a simple structure and is capable of noiseless special reproduction.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a block diagram of a rotating cylinder according to an embodiment of the present invention. In the figure, 1 is a rotary cylinder, 2 and 2' are bonded piezoelectric drive elements, 3 and 3' are magnetic heads with different azimuths for recording and reproducing video signals compatible with standard mode, and 4 and 4' are long heads. Magnetic heads with different azimuths in time mode, 5, 5'
is a magnetic head for FM voice signal, 6 is a fixture, 7
is a magnetic head for height detection.

In the standard mode, before the heads 3, 3' record video signals on the magnetic tape, the tape is loaded into a cylinder and brought to a halt. At this time, it is confirmed that the rotational speed of the rotary cylinder 1 is at a normal value, and a height detection signal is recorded by the height detection head 7. The azimuth of head 7 is head 4
and 4' azimuth, and head 7.
The head widths of 4 and 4' are kept the same. Next, the above-mentioned height detection signal is regenerated in the long-time mode heads 4 and 4', and different electric fields are applied to the voltage drive elements 2 and 2' so that the output of heads 4 and 4' is maximized. Apply. The applied voltages when the outputs of both heads 4 and 4' reach their maximum are recorded, and the tape is run at a regular speed to record video signals on the tape using heads 3 and 3'. Since the height of height detection head 7 and the height of heads 4, 4' or heads 3, 3' match, if the height of head 7 is adjusted to the standard value, the height of heads 3, 3', 4,
4' is within the standard value range.

2 shows a track written by the height detection head 7, 8 is a magnetic tape, 9 is a track on which a height detection signal is written, 10 is a head 4 or 4' for reproducing track 9, The arrow is head 4,
4' indicates the running direction. As shown in the figure, since the recording track width and the head width of heads 4 and 4' are the same, the output reaches its maximum when heads 4 and 4' are completely on track 9. This is because the height detection head 7 and the heights of the heads 4 and 4' match, it means that the output is maximum.

Effects of the Invention As described above, the present invention uses a magnetic head for height detection to adjust the height of the magnetic head mounted on a piezoelectric drive element, and outputs the voltage applied to the piezoelectric drive element to the head. This has been made possible by finding the maximum value of , so the head on the voltage drive element can be used for both recording and playback. Therefore, since the number of heads and input/output are reduced, it is possible to provide a high-performance VTR capable of noiseless special reproduction with a simple structure.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a rotary cylinder in one embodiment of the present invention, and FIG. 2 is a diagram showing a track on a tape written by a height detection head and a head locus. 1... Rotating cylinder, 2, 2'... Bonded piezoelectric drive element, 3, 3'... Wide head for standard mode, 4, 4'... Head for long time mode, 5,
5'... FM audio head, 6... Fixture, 7...
...Height detection head, 8...Magnetic tape, 9...
Recording track, 10...Head for long time mode.

Claims (1)

[Claims] 1 A magnetic head for video signals is mounted on a bonded piezoelectric drive element whose tip bends when an electric field is applied to the piezoelectric ceramic plate, and is fixed to a rotating cylinder, and the head width is set as above on the rotating cylinder. Attach a recording head for height detection, which is the same as the magnetic head, and before recording the signal on the magnetic tape, use the recording head to write a height detection signal on the tape, and then mount it on the piezoelectric drive element. A rotary cylinder device characterized in that the position of the magnetic head is adjusted by controlling the electric field applied to the voltage ceramic plate so that the reproduction level is maximized.