JPH06333222A - Magnetic recording and reproducing device and its magnetic head driving method - Google Patents

Abstract

PURPOSE:To prevent changing of the projecting amt. of a magnetic head in the processing of tracing a magnetic head on a recording track at the time of reproducing. CONSTITUTION:The free ends of a pair of bimorphs 8, 9 which are fixed at one end to a supporting member 7 and are arranged in parallel are bridged by a means of a flexible bridging piece 10. The magnetic head 5 fixed to the bridging piece 10 distorts a pair of the bimorphs 8, 9 in the same direction at the time the magnetic head 5 fixed to the bridging piece 10 is largely displaced in the track width direction. A pair of the bimorphs 8, 9 when the displacement quantity is 0 are distorted in opposite directions. At least one bimorph 8 is distorted even at the remaining point of time. As a result, the reproduction fault by a contact defect between the magnetic head and a magnetic tape is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus having a function of tracking a magnetic head at the time of reproduction on a recording track and reducing the generation of noise due to a relative displacement between the two, and a magnetic head therefor. The present invention relates to a driving method.

[0002]

2. Description of the Related Art In a helical scan type VTR or the like, if the rotational speed during reproduction differs from the rotational speed during recording,
The track of the magnetic head does not match the recording track, and noise is generated in the reproduced image due to the relative displacement between the two. Therefore, various magnetic head drive devices have been proposed for tracking the magnetic head to the recording track during reproduction. This is roughly classified into two types, one of which uses a bimorph (piezo element in which an electrostrictive element is bonded) to drive a magnetic head for displacement (for example, Japanese Patent Laid-Open No. 55-110).
No. 083), the other is a moving coil type.

An example of the former configuration is shown in FIGS. 3 and 4. A pair of parallel bimorphs 2 and 3 fixed at one end to the support member 1 are bridged at their free ends by a bridging piece 4, and a magnetic head 5 is fixed to the bridging piece 4.
The bridging piece 4 is made of carbon fiber or the like having flexibility in the bending direction, and 6 is a mounting member.

The pair of bimorphs 2 and 3 to which a predetermined voltage is applied are distorted by the electrostrictive effect as shown in FIG. 4A, and the magnetic head 5 is displaced in the track width direction.
Since the amount of this displacement changes depending on the applied voltage, the circuit is configured to detect the envelope of the reproduction signal and control the applied voltage.

[0005]

However, since the protrusion amount of the magnetic head 5 at the maximum displacement is reduced by the dimension d as compared with the protrusion amount of the displacement amount 0 shown in FIG. There is a problem that the contact between the magnetic head 5 and the magnetic tape cannot be satisfactorily obtained in a region where the flying height of the tape is large. In addition, L = 20 mm, the amplitude of the magnetic head 5 is 0.
When the displacement amount is 0, the head protrusion amount when the displacement amount is 8 mm is reduced from 0.04 mm to 0.025 mm by half.

On the other hand, the moving coil type has a structural defect that it is difficult to shut off leakage magnetism and miniaturize it because the exciting coil is mounted on the leaf spring that supports the magnetic head.

Therefore, it is an object of the present invention to provide a magnetic recording / reproducing apparatus and a method of driving the magnetic head, which has a structure in which a bimorph is used and whose protrusion amount is small even when the magnetic head is displaced.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a plate member extending from a fixed end fixed to a support member to a free end thereof at a predetermined distance so as to be substantially parallel to each other. A pair of bimorphs arranged opposite to each other, a flexible bridging piece bridging the free ends of the pair of bimorphs to each other, and fixed to the outer end of the bridging piece and protruding to the opposite bimorph side An independent control voltage is applied to each of the magnetic head and the pair of bimorphs to generate distortion, and the distortion is generated in a direction substantially perpendicular to the plate surface without changing the protrusion amount in the direction along the plate surface. There is provided a magnetic recording / reproducing apparatus comprising a power supply unit for displacing a magnetic head.

Further, the free ends of a pair of bimorphs, which are opposed to each other at a predetermined interval so that the plate surfaces from the fixed end to the free end are substantially parallel to each other, are mutually connected by a flexible bridging piece. A magnetic head fixed to the bridge piece and protruding to the side opposite to the bimorph, without changing the amount of projection in the direction along the plate surface by applying a voltage to the pair of bimorphs. Distorting the drive in a direction substantially perpendicular to the direction of distorting the pair of bimorphs in the same direction, distorting the pair of bimorphs in opposite directions, and distorting only one of the pair of bimorphs There is provided a magnetic head driving method characterized in that the magnetic head driving method is performed by any one of the following.

[0010]

According to the present invention, in the tracking drive of the magnetic head, in addition to changing the distortion amount of the pair of bimorphs, an independent voltage is applied to each of the bimorphs to add directionality to the distortion. In combination with the peculiar movement of the bridging piece associated therewith, the protrusion amount of the magnetic head can always be kept substantially constant regardless of the displacement amount of the magnetic head in the track width direction. For this reason, the degree of contact between the magnetic head and the magnetic tape does not change during the tracking operation, and the reproduction obstacle due to this does not occur.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

As shown in FIG. 1, each fixed end of a pair of bimorphs 8 and 9 is fixed to a supporting member 7 made of an insulator, and the pair of bimorphs 8 and 9 extends from the fixed end to the free end. The plate surfaces are arranged so as to face each other at a predetermined interval so as to be substantially parallel to each other. The flexible bridging piece 10 bridging the free ends of the pair of bimorphs 8 and 9 with each other is made of carbon fiber or the like and has flexibility in the bending direction. The magnetic head 5 fixed to the outer end of the bridging piece 10 projects to the side opposite to the bimorph. Such a structure is the same as the conventional structure described above, and its external view is represented by FIG.

However, the shape of deformation of the pair of bimorphs 8 and 9 and the bridging piece 10 when a voltage with a large amplitude change is applied is completely different from the conventional one.

In FIG. 1A, the magnetic head 5 is displaced at the maximum amount in the track width direction, that is, the magnetic head 5 is moved.
Shows a state in which is displaced to the uppermost end (or the lowermost end), and the pair of bimorphs 8 and 9 are distorted in the same direction. Further, (c) shows the state at the time when the displacement amount is 0 (at the origin position), and the pair of bimorphs 8 and 9 are distorted in opposite directions. And (b)
Shows a state at an intermediate time, that is, when the magnetic head 5 slightly moves from the maximum displacement position shown in FIG.
Only is distorted.

It is necessary for the magnetic head 5 to be displaced in the track width direction in advance without changing the protrusion amount thereof so that the distortion amounts and the distortion directions of the bimorphs 8 and 9 are controlled as described above. Distortion amount of both bimorphs 8 and 9,
The correlation with the applied voltage to both bimorphs 8 and 9 at that time is written in the read-only memory (ROM). If there is a missing point in the data, it is supplemented so that the magnetic head 5 can be smoothly displaced (vibrated).

Next, a voltage is applied to both the bimorphs 8 and 9 to distort the shape shown in FIG. 1C, that is, the pair of bimorphs 8 and 9 in opposite directions to project the magnetic head 5. The amount is set to a predetermined value, for example, 0.04 mm, and this is set as the origin position. Then, the magnetic head 5 is displaced (vibrated) in the track width direction. At this time,
Since the applied voltage to both the bimorphs 8 and 9 is controlled by the data read from the ROM, it is possible to minimize the change in the protrusion amount of the magnetic head 5. Further, the bridging piece 10 is deformed so as to bring the magnetic head 5 into contact with the magnetic tape at a substantially right angle.

As shown in FIG. 2, the magnetic tape 15 wound around the supply reel 14 travels by the pulling operation by the pinch roller 16 and the capstan 17, and is guided by the guide posts 18 and 19 to the rotating cylinder 20. It is pressed against the mounted recording magnetic head (not shown). Then, it is taken up by the take-up reel 21 while passing between the pinch roller 16 and the capstan 17.

The magnetic head mounted on the rotary cylinder 20 is supported by the above-mentioned bimorph drive body, and the protrusion amount when the position occupied by the magnetic head is displaced to the upper end or the lower end becomes a predetermined value. Is attached to the rotary cylinder 20.

As an example, a pair of bimorphs 8,
Assuming that the length (L) from the fixed end of 9 to the tip of the magnetic head 5 is 20 mm and the amplitude of the magnetic head 5 is 0.8 mm,
The amount of protrusion when the magnetic head 5 changes to the upper end or the lower end is about 0.015 mm less than the amount of protrusion when the pair of bimorphs 8 and 9 is not displaced. Therefore, assuming that the protrusion amount at the time of initial setting is 0.04 mm, the protrusion amount when the magnetic head driving body is attached to the rotary cylinder 20 is 0.05 mm plus 0.015 mm.
It is necessary to keep mm.

By applying the driving method of the present invention to the magnetic recording / reproducing apparatus having the above-mentioned structure, it is possible to reduce the change in the protrusion amount even when the magnetic head is displaced in a predetermined direction with respect to the recording track. Therefore, even if reproduction is performed at a speed different from the recording speed, the output change is small, and there is an effect that a reproduced image without noise is obtained.

[0021]

As described above, according to the present invention, although the bimorph is distorted in the process of tracking the magnetic head on the recording track at the time of reproduction, the protrusion amount of the magnetic head hardly changes and at the time of reproduction. The magnetic head can be always brought into good contact with the magnetic tape without impairing the tracking function in the above.

[Brief description of drawings]

FIG. 1 is a sectional view showing a modification of a pair of bimorphs according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a magnetic tape running system according to an embodiment of the present invention.

FIG. 3 is a perspective view of a conventional magnetic head drive unit.

FIG. 4 is a cross-sectional view showing a modified mode of each portion in the AA cross section of FIG.

[Explanation of reference numerals] 5 magnetic head 7 support member 8, 9 bimorph 10 bridging piece

Claims (2)

[Claims] 1. A pair of bimorphs, which are opposed to each other at a predetermined interval so that plate surfaces from a fixed end fixed to a support member to a free end are substantially parallel to each other, and a pair of bimorphs are free. A flexible bridging piece bridging the ends to each other, a magnetic head fixed to the outer end of the bridging piece and protruding to the anti-bimorph side, and an independent control voltage to each of the pair of bimorphs. A magnetic force applying means for displacing the magnetic head to displace the magnetic head in a direction substantially perpendicular to the plate surface without changing the amount of protrusion in the direction along the plate surface. Recording / playback device. 2. A pair of bimorph free ends, which are arranged to face each other with a predetermined interval so that plate surfaces from the fixed end to the free end are substantially parallel to each other, are mutually connected by a flexible bridging piece. A magnetic head fixed to the bridge piece and protruding to the side opposite to the bimorph, by applying a voltage to the pair of bimorphs without changing the amount of projection in the direction along the plate surface. Displacement of a pair of bimorphs in the same direction, distorting a pair of bimorphs in opposite directions, and distorting only one of a pair of bimorphs A method of driving a magnetic head, characterized in that it is performed by one of the three alternatives.