JPS6338768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating magnetic head device for a helical scan magnetic recording/reproducing apparatus (hereinafter referred to as VTR).

In a helical scan VTR, as the recording track width becomes narrower, it becomes more difficult to scan the recording track correctly, which causes deterioration in image quality due to poor tracking. In order to prevent this, it has been devised to detect this tracking defect by some means during playback and to move the video head in the track width direction to perform correct tracking.

A conventional rotating magnetic head device for performing tracking by moving the video head will be explained with reference to FIG. Reference numeral 1 designates a rotating magnetic head, which is fixed to one end, which is the free end side, of a bimorph plate 35 formed of a piezoelectric material, and the other end of the bimorph plate 35 is attached to a mounting fixture 3.
It is fixedly supported in a cantilevered manner to the rotating upper cylinder 7 via a shaft 9 . The rotary upper cylinder 7 is fixed to the rotary shaft 24 via the rotary disk 17 so as to rotate together with the rotary shaft 24. Rotating cylinder 7
A slip ring 36 is fixed to the holder and constitutes an electrical contact with a brush 37 attached to the fixed side. Further, the bimorph plate 35 and the slip ring 36 are electrically connected by a connection 38. 40 is a magnetic tape.

By applying a voltage through the brush 37 and the slip ring 36, the cantilever-shaped bimorph plate 35 is deflected, and the rotating magnetic head 1 on the outer peripheral side of the rotating upper cylinder 7 is displaced in the axial direction of the rotating shaft 24. Therefore, a voltage is applied to the bimorph plate 3 to correct the track deviation information of the video head during playback detected by some means.
5, it is possible to correct tracking deviations and ensure correct tracking during playback. However, in the above conventional structure, a high voltage of around 100 volts is usually required to bend the bimorph plate 35 by the required amount, and a slip ring and a brush are required to transmit electrical signals. However, there are drawbacks such as noise and reduced reliability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotating magnetic head device which eliminates the above-mentioned drawbacks and allows a rotating magnetic head to be displaced in the direction of the rotation axis without the need for high voltage or slip-ring brushes.

The rotating magnetic head device of the present invention is configured such that a rotating magnetic head fixed to a rotating cylinder is rotated at a predetermined number of rotations to scan a magnetic tape, and the rotating magnetic head is fixed to the rotating cylinder using an elastic member. an elastic member to which a ring made of a high magnetic permeability material is fixed and fixed to the rotating cylinder; and an elastic member disposed between both the elastic members to integrally displace both leaf springs in the axial direction of the rotating cylinder. The ring is provided with a connecting member fixed as shown in FIG.

Hereinafter, an embodiment of the rotating magnetic head device of the present invention will be described with reference to FIGS. 2 and 3, using the same reference numerals for the same parts as those of the prior art and omitting the explanation of the same parts. Reference numerals 1 and 2 denote rotating magnetic heads, and the other free ends of leaf springs 3 and 4 made of elastic material are fixed to the center side of the rotating cylinder 7 via support pieces 5 and 6 (the outer peripheral side of the rotating upper cylinder). ) is fixed. disk 17
A base 16 is attached to the base 16, and two leaf springs 11 and 15 made of elastic material are attached to the base 16, and the leaf springs 11 and 15 are formed in a disc shape.
Rings 10 and 14 made of a high magnetic permeability material such as soft ferrite are bonded to the outer circumferential sides, respectively. A ring-shaped core 9 having a plurality of projections 41 facing each other in the axial direction is fixed to a fixing member 18 on the ring 10, and the core 9 is made of a ferromagnetic material such as iron. FIG. 3 shows an enlarged view of this part, and shows the protrusion 4 provided on the core 9.
1 has an electromagnetic coil 8 wound around it. Similarly, the ring 14 also has a core 13 having a plurality of protrusions 41 facing in the axial direction and around which the electromagnetic coil 12 is wound.
is fixed to the fixed member 18. Fixed member 28
is fixedly supported on the set via a plate 28.

In FIG. 3, when a current is passed through the electromagnetic coil 8, a magnetic flux 42 is generated as indicated by an arrow, and as a result, the ring 10 receives an attractive force toward the electromagnetic coil 8. By arranging the electromagnetic coil 8 and the protrusions 41 at equal intervals on the circumference, the ring 10 receives an attractive force at equal intervals on the circumference. The ring 10 is a leaf spring 11
Since the leaf spring 11 is bonded to the top, the leaf spring 11 is bent upward due to this suction force. Reference numeral 26 denotes a connecting member, and the connecting member 26 is arranged so as to contact the leaf spring 11 and the leaf spring 4 at their respective spherical tips.The connecting member 26 also passes through the rotating upper cylinder 7, and the connecting member 26 extends in the hole diameter direction at the penetrating portion. It is installed so that it can move up and down smoothly without any play. When the base 16 is attached to the disk 17, the leaf springs 4 and 11 are each slightly bent and in contact with the connecting member 10, and the connecting member 26 is further compressed by the leaf springs 4 and 11 on both sides in the axial direction. It is installed in a constricted state under pressure. When the leaf spring 11 is displaced upward in this state, the connecting member 26 is displaced accordingly, so that the leaf spring 4 is similarly deformed upward and the rotating magnetic head 2 is also displaced in the same direction. Therefore, by passing a current through the electromagnetic coil 8, the rotating magnetic head 2 can be displaced in a direction parallel to the rotating shaft 24. In addition, the electromagnetic coil 12 and the rotating magnetic head 1
It is also configured in exactly the same way as above, and can be displaced. That is, by passing a current through the electromagnetic coil 12, the leaf spring 15 is displaced upward, thereby displacing the connecting member 25, deforming the leaf spring 3, and displacing the rotating magnetic head 1 upward.

As mentioned above, in this embodiment, the ring 1
Only the suction force acts on 0 and 14. Generally, in order to track a video track, it is necessary to apply displacement in both the up and down directions. For this purpose, it is sufficient to predict the amount of displacement necessary for tracking in advance and apply a bias displacement corresponding to the amount of displacement. That is, by flowing an appropriate amount of bias DC current through the electromagnetic coil, it is possible to vertically displace the electromagnetic coil around this bias displacement. Incidentally, by applying this bias displacement, it is possible to simultaneously adjust the head height and the head level difference of both heads during assembly.
Even if the head level difference or height changes for some reason during use, the amount of change can be detected using an appropriate detection means, and the bias current can be changed to the correct value. Further, as is clear from the above, since the rings 10 and 14 have a uniform shape in the circumferential direction, when a current is passed through the electromagnetic coil, the rings 10 and 14 receive a uniform attractive force during rotation. Therefore, uneven rotation of the rotating upper cylinder 7 is not caused. Furthermore, 27 is a magnetic shield plate for the rotating magnetic head.
Materials such as permalloy are preferred. Furthermore, signals are sent and received to and from the rotating magnetic head via the rotary transformer rotor 19 and rotary transformer stator 20. The rotating shaft 24 is the lower rotating cylinder 21
It rotates while being supported by an upper bearing 22 and a lower bearing 23 inside.

FIG. 4 shows another embodiment. In the above embodiment, two rotating magnetic heads were changed using separate electromagnetic coils, but in this embodiment, two rotating magnetic heads were driven simultaneously using one electromagnetic coil, and the high speed The rotary magnetic heads 1 and 2 are simultaneously displaced by deformation of a leaf spring 30 to which a ring 14 made of a magnetically permeable material such as ferrite is fixed on the outer circumferential side. The problem with this embodiment is to correctly displace the heads at the time of head switching. That is, the structure of this embodiment constitutes a resonant system using various springs and masses, and structurally it is not possible to obtain a very high resonant frequency. Therefore, it is impossible to change the displacement of the leaf spring 30 required for the rotating magnetic head 1 to the displacement of the leaf spring 30 required for the rotating magnetic head 2 as quickly as necessary.

As an idea in this case, in this embodiment, the coil is divided into two parts: the electromagnetic coil 32 on the side closer to the rotating magnetic head 1 and the electromagnetic coil 33 on the side closer to the rotating magnetic head 2 at the time of head switching. Although the same current is passed, at the time of switching the heads, currents of different magnitudes may be passed through the electromagnetic coils 32 and 33 to give the required displacements to the rotating magnetic heads 1 and 2, respectively. By doing this, the leaf spring 30 undergoes a fairly complicated deformation, but this is possible if the necessary current value is determined in advance through calculations, experiments, etc.

As described above, the rotating magnetic head device of the present invention has a high magnetic permeability attached to the elastic material which rotates integrally with the rotating cylinder which is fixed via the connecting member and the elastic member fixed to the rotating cylinder to which the rotating magnetic head is attached. By attracting a ring of material through an electromagnetic coil attached to the stationary side, the rotating magnetic head can be displaced in the axial direction without the need for high voltage, slip rings, or brushes as in the past. It is something that you have.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional rotating magnetic head device.
FIG. 2 is a sectional view of an embodiment of the rotating magnetic head device of the present invention, and FIG. 3 is a detailed perspective view of section A in FIG.
FIG. 4 is a sectional view of another embodiment of the rotating magnetic head device of the present invention. 1...Rotating magnetic head, 3, 4, 11, 15,
30...Plate spring, 7...Rotating upper cylinder, 8,1
2, 32, 33... Electromagnetic coil, 10, 14...
Ring, 25, 26... Connecting material, 40... Magnetic tape.

Claims (1)

[Claims] 1. A rotating magnetic head device configured to scan a magnetic tape by rotating a rotating magnetic head fixed to a rotating cylinder at a predetermined rotation speed, comprising: an elastic material for fixing the rotating magnetic head to the rotating cylinder; A ring made of a high magnetic permeability material is fixed and an elastic member is fixed to the rotating cylinder, and a connection is arranged between the two elastic members and fixed so that both elastic members are displaced together in the axial direction of the rotating cylinder. 1. A rotating magnetic head device comprising: a magnetic coil; and an electromagnetic coil attached to a stationary side and axially opposed to the ring.