JPH03122875A - Actuator for driving magnetic head - Google Patents

Abstract

PURPOSE:To improve the density of magnetic flux, to make the constant of torque large, simultaneously to reduce the inertial moment of a movable coil and to realize the high-speed access of a magnetic head by preparing two sets of opposed magnets and arranging them at prescribed intervals so that they interpose the movable coil in a circular arc shape. CONSTITUTION:A magnetic circuit is constituted by fixing the top and bottom of the flat shaped movable coil 35 formed in the circular arc shape to the end part on the opposite side to the magnetic head assembling body attachment part of a rotating carriage 31 through a prescribed gap with the aid of supporting arms 31a and 31b so that the effective part of the circular arc shaped coil 35 is opposed to the rotary shaft 41 of the carriage 31 in parallel and combining the coil 35 with the aid of a yoke 37 so that it is interposed with the aid of the sets of circular arc shaped permanent magnets 38a, and 38b, 39a and 39b. Consequently, the rigidity of the magnetic circuit is improved by the shape and the fixing structure of the movable coil 35. Besides, since there is not the mass part of excess weight on the outside from a torque generation part, the generating torque/inertial moment can be made large. Moreover, since there is no central magnetic pole in the magnetic circuit, the density of the magnetic flux B can be improved. Thus, the accurate head positioning is realized at a high speed.

Description

[Detailed Description of the Invention] [Summary] Regarding a magnetic head drive actuator for positioning a magnetic head in a magnetic disk device on a predetermined track of a magnetic disk, the magnetic flux density of a fixed magnetic circuit is increased to rotate a rotating carriage. The purpose is to increase the torque constant, reduce the moment of inertia of the moving coil, and increase the ratio of driving force to mass (to enable high-speed access of the magnetic head. A plurality of magnetic head assemblies are supported in parallel at predetermined intervals in the upper direction at one end, and a flat moving coil is mounted on the yoke at the end of the rotating carriage opposite to the end. An actuator for driving a magnetic head, which is supported so as to pass between magnets arranged opposite to each other, wherein the movable coil has an arc-shaped coil surface, and the coil surface is parallel to the rotation axis of a rotating carriage. The opposing magnets are composed of two pairs and have an arc shape corresponding to the shape of the moving coil, and are attached to the supporting arm portions facing the upper and lower ends of the carriage so as to sandwich the moving coil. They are arranged with a predetermined gap between them.

[Industrial application field]

The present invention relates to an actuator for driving a magnetic head for positioning a magnetic head in a magnetic disk drive on a predetermined track on a magnetic disk, and particularly to a swing type actuator.

Magnetic disk drives, which are widely used as external storage devices for computer systems, have become faster, denser, and larger in capacity as the information to be processed becomes more diverse and the amount of information increases. Access actuators require faster and more accurate positioning.

Therefore, as an actuator, the driving power is larger (force r/quality 51m is large), and there is less mechanical vibration that impedes precise positioning (high rigidity).
Structures with properties are needed.

[Conventional technology]

For example, as shown in FIG. 5, a typical conventional swing-arm type actuator for driving a magnetic head has a magnetic head slider 4 held at the side of the tip via a support spring 3. A rotary carriage 1 that integrally supports a plurality of helad arms 2, so-called head assemblies, is arranged so as to be rotatable in the direction of arrow B about a fixed shaft 7, and a coil is wound around a rectangular cylindrical bobbin at the other end. A rectangular cylindrical movable coil 5 is fixed, and the movable coil 5 is placed in a magnetic field in an air gap between a pair of permanent magnets 6b and 6c disposed facing each other by a vertical U-shaped yoke 6a in a fixed magnetic circuit 6. There is a type of actuator that is inserted into the central magnetic pole 6d and combined with the permanent magnets 6b+6c. Further, as shown in FIG. 6, a rotating carrier 11 integrally supports a plurality of helad arms 12 each holding a magnetic head slider 14 via a support spring 13 on the side of the tip. B
A rectangular cylinder-shaped movable coil unit 5 is fixed to the other end of the rectangular cylinder bobbin, which is rotatably arranged in the direction of , and has a coil wound around an arcuate rectangular cylinder bobbin through a predetermined space toward the fixed shaft 17 side at the other end. The movable coil 15 is inserted into an arc-shaped center magnetic pole 16d arranged in an air gap magnetic field between a pair of permanent magnets 16b and 16C arranged in an arc shape facing each other by a horizontal U-shaped yoke 16a in a fixed magnetic circuit 16. A type of actuator configured in combination with the above conditions has been proposed.

By passing a predetermined drive current through both types of moving coils 5 and 15, a direct drive force f is generated.
The driving force moves each movable coil 5° 15 in the direction of the arrow to move each of the carriages 1 and 11 to the rotating shaft 7.
, 17 in the direction of arrow B, and move the magnetic hent sliders 4 and 14 in the direction opposite to the moving direction of the moving coil 5. The magnetic head is positioned at this position.

[Problem to be solved by the invention]

By the way, in order to speed up head access using the above-mentioned swing type actuator, the torque constant K (K=Bj!r, B: magnetic flux density, l: coil length, r: coil equivalent radius) of the actuator should be increased. There is a need to.

Therefore, in the former actuator shown in FIG. 5, it is sufficient to increase the magnetic flux density B in order to increase the torque constant K, but if the magnetic flux density B is increased, the central magnetic pole 6d in the fixed magnetic circuit 6 becomes magnetically saturated. There is a structural problem in that To avoid such problems, the yoke 6a
It is possible to increase the wall thickness of the movable coil 5, but in this case, the equivalent radius r of the moving coil 5 becomes small and the torque constant K cannot be increased to a large extent, which limits high-speed driving.

Furthermore, in the latter actuator shown in FIG. 6, the inner and outer portions of the movable coil 15 on the side of the rotating carriage 11 are effective parts of the torque, so the torque constant K can be increased by an amount corresponding to the larger coil equivalent radius r. can be done, but
However, since it is necessary to increase the magnetic flux density B, there is a problem that the center magnetic pole 16d in the fixed magnetic circuit 16 becomes magnetically saturated, similar to the former case.

Therefore, as an actuator that can increase the magnetic flux density B without causing such magnetic saturation of the yoke, a seven slider 24 is held at the side of the tip via a support spring 23, as shown in FIG. A rotating carriage 21 that integrally supports a plurality of helad arms 22 is attached to a fixed shaft 2.
A flat-shaped movable coil 25 is fixed to the other end as shown in the figure, and the movable coil 25 is arranged to be rotatable in the direction of the arrow B with the fixed magnetic circuit 26 as the center. A type has been proposed in which a drive coil motor is constructed by combining a pair of permanent magnets 26b and 26c disposed in an air gap magnetic field between a pair of permanent magnets 26b and 26c opposed to each other by a letter-shaped yoke 26a.

Since such an actuator does not have a central magnetic pole, the thickness of the yoke 26a in the fixed magnetic circuit 26 can be increased even if the magnetic flux density B is increased, which is advantageous in terms of magnetic saturation. Since the parts are large and heavy, the moment of inertia during driving tends to become large, and effective torque is generated only at the inner circumference, which is disadvantageous in terms of torque constant. Since the coil 25 has a flat shape and is supported on a cantilever, the rigidity is low and mechanical vibrations are likely to occur.

In view of the above-mentioned conventional situation, the present invention increases the magnetic flux density of the fixed magnetic circuit to increase the torque constant for rotating the rotating carriage, reduces the moment of inertia of the moving coil, and increases the ratio of driving force to mass. An object of the present invention is to provide a novel magnetic head drive actuator that enables high-speed access to a magnetic head.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention supports a plurality of magnetic head assemblies arranged in parallel at a predetermined interval in the vertical direction at one end of a rotating carriage remote from the center of rotation, and the magnetic head assemblies are attached in one part. An actuator for driving a magnetic head, in which a flat moving coil is supported at the end of a rotating carriage on the opposite side so as to pass between magnets arranged oppositely on a yoke, the moving coil having an arcuate coil surface. and its coil surface is attached to a support arm portion facing the upper and lower ends of the rotating carriage with its coil surface parallel to the rotation axis of the carriage, and the opposing magnets are composed of two pairs and correspond to the shape of the moving coil. It has a circular arc shape, and is arranged with a predetermined gap between it and the moving coil so as to sandwich the moving coil.

[For production]

In the present invention, the magnetic head assembly of the rotating carriage is mounted by attaching a flat movable coil formed into an arc shape with a predetermined gap at the opposite end of the rotating carriage, so that the effective part of the arc-shaped coil rotates the carriage. The upper and lower sides are fixed by support arms so as to face parallel to the axis, and this flat moving coil is sandwiched between two pairs of arc-shaped magnets placed opposite each other by a yoke to form a magnetic circuit. The shape and fixed structure of the coil increases rigidity, and since there is no extra heavy mass part outside the torque generating part, the generated external torque/moment of inertia can be increased.Furthermore, since there is no central magnetic pole in the magnetic circuit, the magnetic flux density B can be raised.

As a result, precise head positioning can be achieved at high speed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a magnetic head driving actuator according to the present invention.

In the figure, reference numeral 31 denotes a rotating carriage integrally constructed with a plurality of head arms 32, which is disposed on a fixed shaft 40 so as to be rotatable in the direction shown by arrow B, and each of the head arms 3
A magnetic head slider 34 is supported by a support spring 33 at the tip end side of each of the magnetic head sliders 2 .

Further, at the other end of the rotating carriage 31, a flat movable coil 35 formed into an arc shape is provided as shown in FIG.
However, the arc-shaped coil surface faces the fixed shaft 40, which is the center of rotation of the carriage 31, in parallel.

The upper and lower parts are fixed by adhesive or the like between support arms 31a and 31b with a predetermined gap. Due to the flat shape and fixed structure of the moving coil 35, the rigidity of the flat moving coil 35 is significantly increased.

The flat movable coil 35 is composed of two pairs of arc-shaped permanent magnets 38a and 38b which are arranged oppositely by a horizontal U-shaped yoke 37 of a fixed magnetic circuit 36 as shown in FIG.
and combined in a form sandwiched between 39a and 39b,
In addition, the actuator is movable in the direction indicated by arrow A.

The torque generating part of the rotating carriage 31 in this structure,
That is, since there is no extra heavy mass part on the outside of the flat moving coil 35, the moment of inertia is small and the ratio of the generated torque to the moment of inertia can be increased. Further, since the fixed magnetic circuit 36 does not have a central magnetic pole and the outer yoke 37 can have any thickness, it is possible to increase the magnetic flux 6 density B without worrying about magnetic saturation as in the conventional case.

In addition to the fixed magnetic circuit shown in FIG. 3, the fixed magnetic circuit combined with the flat movable coil 35 may include a fixed magnetic circuit on one side of a horizontal U-shaped yoke 47 as shown in FIG. Alternatively, the same function can be obtained by combining the two arc-shaped permanent magnets 48 and 49 with a fixed magnetic circuit 46 having a structure in which the magnetic polarities thereof are different.

〔Effect of the invention〕

As is clear from the above description, according to the magnetic head drive actuator according to the present invention, the rigidity of the moving coil can be increased with a simple configuration, the moment of inertia can be reduced, and the magnetic flux density of the fixed magnetic circuit can be increased. As a result, it is possible to increase the torque constant for rotating the rotating carriage, and has excellent advantages such as being able to perform precise head positioning at high speed, and has great practical effects.

FIG. 7 is a perspective view for explaining still another example of the conventional magnetic head driving actuator.

[Brief explanation of drawings]

Part 1 is a perspective view showing an embodiment of the magnetic head driving actuator according to the present invention, Fig. 2 is an enlarged perspective view showing a moving coil in the magnetic head driving actuator according to the invention, and Fig. 3 is the present invention. FIG. 4 is a partial perspective view for explaining one embodiment of the fixed magnetic circuit of the magnetic head drive actuator according to the present invention; FIG. 4 is a partial perspective view for explaining another embodiment of the fixed magnetic circuit of the magnetic head drive actuator according to the present invention; 5 is a perspective view showing one example of a conventional actuator for driving a magnetic head; FIG. 6 is a perspective view showing another example of a conventional actuator for driving a magnetic head; In the figures, 31 is a rotating carriage, 31a and 31b are support arms, 32 is a helad arm, 33 is a support spring, 34 is a magnetic head slider, 35 is a flat moving coil, and 36.4
6 is a fixed magnetic circuit, 37.47 is a yoke, 38a, 38
b, 39a, 39b, 48.49 are permanent magnets, and 40 is a fixed shaft, respectively. 36-tall barrier eight-ro road? Door stone - cat / 1qIW 7L to S
l! q Wh7F'l°NilFigure 6

Claims (1)

[Claims] A plurality of magnetic head assemblies are supported vertically in parallel at predetermined intervals at one end of the rotating carriage (31) remote from the center of rotation, and a plurality of magnetic head assemblies are supported in parallel at predetermined intervals in the vertical direction, and a plurality of magnetic head assemblies are supported in parallel at predetermined intervals in the vertical direction at one end of the rotating carriage (31) remote from the center of rotation. A flat moving coil (
A magnet (38a
, 38b, 39a, 39b), the movable coil (35) has an arcuate coil surface, and the coil surface is connected to a rotating carriage (35). 31) rotation axis (4
The movable An actuator for driving a magnetic head, which has an arc shape corresponding to the shape of a coil (35), and is arranged with a predetermined gap between the movable coil (35) and the coil so as to sandwich the movable coil (35). .