JPS5853407B2 - Rotating magnetic head device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary head type magnetic recording/reproducing device that uses two rotating magnetic heads alternately to sequentially record or reproduce signals as recording tracks inclined with respect to the longitudinal direction of a magnetic tape. This relates to a rotating magnetic head device in a device.
As a means for automatically achieving the optimum tracking state during playback, a toroidal bonded piezoelectric vibrator having opposite polarization directions on the left and right sides of a predetermined diameter of the toroidal piezoelectric vibrator is used. The driving power source of the rotary magnetic head is unified, and the assembly and adjustment operations of the rotary magnetic head are simplified and assembly accuracy is improved.

In a rotating head type magnetic recording/reproducing device, the rotating magnetic head must accurately scan the recording track of the magnetic tape in order to obtain an accurate reproduction signal.

For this reason, automatic tracking is performed to automatically move the magnetic head to the center of the recording track when the magnetic head is deviated from the recording track.

Automatic tracking is also performed when the running speed of the magnetic tape is arbitrarily changed during playback.

As the automatic tracking means, conventionally, a rotating magnetic head height variable means using a bimorph vibrator made of two piezoelectric vibrators bonded together is interposed between the rotating magnetic head and the rotating shaft of the drum motor. Methods have been used to control the voltage applied to the bimorph oscillator.

However, in these rotating magnetic head devices, two magnetic heads are bonded to separate bonded piezoelectric vibrators, and the bonded vibrators are fixed to a rotating cylinder.

For this reason, the displacement characteristics of the two magnetic heads occur due to the difference in the characteristics of the two bonded piezoelectric vibrators, so two different circuits are required to move the two magnetic heads.

Furthermore, in the processing of bonded vibrators, piezoelectric vibrators are difficult to process because they are thin and small, and are difficult to handle because they are easily broken.

Therefore, it takes time and increases costs.

Furthermore, during assembly, it is necessary to adjust the protrusion amount of the two magnetic heads separately, and it is also necessary to adjust the angle index between the two magnetic heads, making the work extremely complicated and reducing the time required for assembly. This also leads to an increase in cost as the length of the

In order to eliminate such drawbacks, the present invention provides a rotating magnetic head device that is equipped with an annular piezoelectric vibrator that positions a magnetic head on a recording track, and that contributes to simplifying processing, assembly, and adjustment work, and improving assembly accuracy. This is what we provide.

An embodiment of the rotating magnetic head device of the present invention is shown in FIG.
This will be explained in detail with reference to FIG.

In FIG. 1, figure a shows a bonded annular vibrator made by bonding together two annular piezoelectric vibrators 1a and 1b having different inner diameters, and figure b is a side view thereof.

The arrows indicate the polarization direction, and the polarization directions are opposite on the left and right sides of the predetermined diameter XX.

In order to make the polarization directions opposite when dividing a single ring-shaped piezoelectric pendulum with respect to its diameter, it is possible to separate the electrodes into two in advance and apply a DC voltage with opposite polarity to each electrode. It can be easily done by doing.

FIG. 2 shows the annular bonded vibrator 1 shown in FIG. The figure shows the installation using jigs 4 and 4'.

The annular bonded vibrator 1 is attached to the rotary cylinder 5 using jigs 4 and 4' at the portion where the polarization direction changes (diameter X-X).

Figure b is a front view, with arrows indicating the polarization direction.

When the outer electrodes of the annular bonded vibrator 1 are short-circuited and the ■ signal shown in Figure C is supplied, it will bend in an S-shape as shown in the figure. The magnetic heads 2 and 2' also move accordingly, and the magnetic head 2 becomes higher and the magnetic head 2 becomes lower.

When the polarity of the DC signal is reversed, the deflection of the annular bonded vibrator 1 is reversed, and the magnetic head 1 becomes lower and the magnetic head 2 becomes higher.

Therefore, by detecting the track misalignment of the magnetic heads and inputting a signal corresponding to the detected amount to the piezoelectric vibrator drive circuit and supplying its output to the vibrator, the two magnetic heads are displaced and a very good reproduced signal can be obtained. That's what you're trying to get.

Unlike the conventional example, this has the great advantage of requiring only one vibrator drive circuit and two vibrator lead wires.

In addition, since the two magnetic heads are not attached to separate bimorph vibrators, but to one annular bonded vibrator, consideration is given to differences in the displacement characteristics of the individual bonded vibrators. Since it is an annular piezoelectric vibrator, it is easy to process, and the effective displacement length is longer than that of a conventional flat plate laminated vibrator that is attached to a rotating cylinder, so the vibrator can be made thicker, making it easy to handle and sturdy. It is also worth mentioning that it can be done.

Furthermore, when assembling the magnetic head, if the magnetic head substrates 3, 3' with the magnetic heads attached are accurately adhered to the predetermined positions of the annular bonded vibrator 1, easy adjustment will be possible when installing it on the rotating cylinder. That's all you need.

In this way, according to the invention, compared to the conventional method, only one vibrator drive circuit is required, making the bonded piezoelectric vibrator more durable, and the processing, assembly, and adjustment work are simplified, and the magnetic field improves the accuracy of the assembly work. A rotary magnetic head device of variable head height type is obtained.

In addition, in the present invention, since the polarization direction is reversed on the left and right sides of a predetermined diameter of the annular piezoelectric vibrator, when this annular piezoelectric vibrator is driven by one drive circuit, one magnetic head If the displacement corresponds to the track deviation, then
The other side will be displaced by the same amount of displacement to the opposite side.

In other words, the piezoelectric vibrator moves up and down by approximately the same amount during one rotation of the cylinder, and as a result, reducing the hysteresis of the piezoelectric vibrator results in, for example, stopping the playback operation and then moving the magnetic head. Since there is little hysteresis of the piezoelectric vibrator when recording starts, a recording trajectory that more closely meets the standards can be obtained.

Furthermore, driving the piezoelectric vibrator in an alternating current manner as described above causes less depolarization of the piezoelectric vibrator compared to driving in only one direction, so that the piezoelectric vibrator remains stable for a long period of time. Good operation can be expected.

[Brief explanation of the drawing]

Fig. 1a is a perspective view showing one example of a piezoelectric vibrator used in the present invention, b is a front view of the same, Fig. 2a is a plan view of one embodiment of the present invention, b is a side view of the same, and C FIG. 2 is a side view showing the same operating state. 1at1b...... Annular piezoelectric vibrator, 2, 2'.
...Magnetic head, 4,4'...Jig for installation, 5...Rotating cylinder 6...Support stand.

Claims (1)

[Claims] 1. A magnetic head is fixed on a circular piezoelectric vibrator whose polarization directions are opposite to each other on the left and right sides of a predetermined diameter, so as to be located on the left and right sides of the diameter, respectively, and the circular piezoelectric vibration A rotary magnetic head device characterized in that the piezoelectric vibrator is fixed on a rotary cylinder at a position having the diameter described above so that the center of the piezoelectric vibrator substantially coincides with the center of the rotary cylinder.