JP3066438B2 - Magnetic head actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving coil type magnetic head actuator for moving a magnetic head for reading and writing information in a magnetic disk drive along a recording surface of a magnetic disk by swinging about one axis. .

[0002]

2. Description of the Related Art In recent years, with the expansion of the range of use of computers in society, there has been an increasing demand for magnetic disk devices used as external storage devices of the computers to have a large capacity and a small size. On the other hand, in order to realize high-speed processing in a computer, there is a demand for a faster access time in a magnetic disk device. The realization of a high-speed operation is strongly desired.

As a magnetic head actuator capable of high-speed operation, a moving coil type actuator has been put to practical use. FIG. 5 is a plan view showing a main part of a magnetic disk drive provided with a conventional magnetic head actuator.

The magnetic head actuator is pivotally supported about a pivot 60, and has a magnetic head 62 fixed to the tip of a carriage 61 protruding from one side thereof and protruding from the other side. A rotor 6 in which a drive coil 64 having an arc-shaped cross section centered on the pivot 60 is fixed to the tip of the support arm 63, and a pair of arc-shaped rotors are provided along the inside and outside of the drive coil 64, respectively. A stator consisting of an inner yoke 72 and an outer yoke 73 holding magnets 70 and 71, respectively, is housed in a common actuator housing 7, and this actuator housing 7 is provided at one corner of a box-shaped housing 8 for housing a magnetic disk 9. Is sealed and fixed in a rectangular opening formed by cutting out a notch.

In this magnetic head actuator, a current is applied to a winding of the drive coil 64 in a direction perpendicular to the plane of the drawing, so that a magnetic circuit formed between the inner yoke 72 and the outer yoke 73 holding the magnets 70 and 71 is formed. A rotational force is applied to the distal end of the support arm 63 holding the drive coil 64, and the rotational force of the rotor 6 generated around the pivot 60 within a predetermined angle range by the rotational force causes the magnetic head 62 at the distal end of the carriage 61 to move. The recording surface of the magnetic disk 9 is accessed in a substantially radial direction. At this time, the acceleration generated in the magnetic head 62 is obtained by the following equation.

[0006]

In this equation, Kα is an acceleration constant indicating the acceleration of the magnetic head 62, r _O is the radius of rotation of the magnetic head 62 about the pivot 60, and r ₁ is the radius of rotation of the drive coil 64. Bl is a force constant indicating the magnitude of the rotational force applied to the rotor 6 and is a function of the radius of gyration r _{O. As} a product of the magnetic flux density B of the magnetic circuit and the coil length l of the drive coil 64, Further, J is the moment of inertia of the rotor 6 and is a function of the weight of each part of the rotor 6 and the turning radii r ₀ and r ₁ .

In a moving coil type magnetic head actuator, a driving coil 64 fixed to the rotor 6 is used.
Is lightweight, the moment of inertia J in equation (1)
Can be kept small, a large acceleration constant Kα can be obtained, and high-speed access is possible.

[0009]

As apparent from the above equation (1), in the moving coil type magnetic head actuator, the ratio of the rotation radius r ₁ of the drive coil 64 to the rotation radius r ₀ of the magnetic head 62 ( By further selecting r ₁ / r ₀ ), it is possible to further increase the speed,
According to the calculation based on the actual shape of the rotor 6, it has been found that the maximum acceleration constant Kα is obtained in the range where the ratio is 0.4 to 0.5.

However, since the internal space of the actuator housing 7 for accommodating the rotor 6 and the stator of the magnetic head actuator is limited to meet the above-mentioned demand for downsizing of the magnetic disk drive, the rotational radius r _{1 of the} drive coil 64 is limited. It is difficult to ensure that the above-mentioned ratio is appropriate with respect to the radius of rotation r ₀ of the magnetic head 62 determined according to the size of the magnetic disk 9, thereby simultaneously realizing miniaturization and speeding up. There was a problem that could not be done.

In the conventional magnetic head actuator having the above-described structure, the heat generated by the drive coil 64 with the repetition of the high-speed access is confined in the closed space formed by the actuator housing 7 and the housing 8. However, due to the influence of the heat, there is a problem that the reliability of the information reading and writing operations by the magnetic head 62 is reduced.

The present invention has been made in view of such circumstances, and realizes a rotation radius of a drive coil having an appropriate ratio to a rotation radius of a magnetic head without obstructing miniaturization of the entire magnetic disk drive. It is another object of the present invention to provide a magnetic head actuator that enables high-speed access, promotes the dissipation of heat generated by a drive coil to the outside, and effectively alleviates a decrease in reliability due to the influence of the heat. .

[0013]

FIG. 1 is a schematic perspective view, partially cut away, of a magnetic disk drive provided with a magnetic head actuator according to the present invention. The actuator is sealed and fixed in an opening formed by cutting out one corner of the box-shaped housing 3 for accommodating the magnetic disk 4, and a magnetic head is provided on one protruding end.
A rotor housing 30 supporting the rotor 1 to which the rotor 12 is mounted via the pivot 10; and a stator housing 31 fixed to the outside of the rotor housing 30 and having an outer yoke 23 as a peripheral wall constituting a magnetic circuit for driving the rotor 1. And

[0014]

According to the present invention, a rotor housing 30 for supporting the rotor 1 and a stator housing 31 for holding a stator constituting a magnetic circuit for driving the rotor 1 are separately formed. yoke
23, the rotation radius r ₁ as large as possible on the drive coil side of the rotor 1 along the outer yoke 23 is realized,
While obtaining a desired ratio to the radius of rotation r _{0 of} 12 and enabling high-speed access, heat generated by repeated access is dissipated to the outside via the outer yoke 23 and is affected by heat during read and write operations. Mitigating reliability degradation.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 2 is a plan view showing a main part of a magnetic disk drive provided with a magnetic head actuator according to the present invention.

The magnetic head actuator according to the present invention has a magnetic head attached to the end of a carriage 11 projecting from one side.
12, a drive coil 14 having an arc-shaped cross section centered on the pivot 10 is fixedly mounted on the tip of a support arm 13 protruding on the other side, and is rotatably supported around the pivot 10. The magnetic disk 4 accommodates the rotor 1 and a stator comprising an inner yoke 22 and an outer yoke 23 which respectively hold a pair of arc-shaped magnets 20, 21 along the inside and outside of the drive coil 14, respectively. It is formed at one corner of the box-shaped housing 3.

The corner portion of the housing 3 has a rectangular opening and is cut out. In this opening, a rotor housing 30 for rotatably supporting the rotor 1 via a pivot 10 is provided.
Outside the rotor housing 30, a stator housing 31 for housing the stator is fixed as described later. FIG. 3 is an external perspective view of the rotor housing 30.

As shown in the figure, the rotor housing 30 has a trapezoidal bottom plate 32 and a top plate 33 opposed to each other at an appropriate distance.
Each of the oblique sides is connected by a pair of side plates 34, 34, and a rectangular opening is formed over the entire surface of each of the long side and the short side of the bottom plate 32 and the top plate 33. On the surfaces of the bottom plate 32 and the top plate 33 facing each other, a pair of recesses 35, 35 are formed at substantially the center of each long side, and these recesses 35, 35 are formed in FIG. As shown, the pivot 10 of the rotor 1 is engaged and fixed. The edges of the side plates 34, 34 at the openings on the short sides of the bottom plate 32 and the top plate 33 are substantially parallel to the pivot 10 installed between the recesses 35, 35, and inwardly substantially perpendicular to each other. A pair of fixing flanges 36, 36 protrude toward the fixing flange 36, 36.
One through hole 37, 37 is formed substantially at the middle of the through hole 33.

Further, bolt holes 38, 38,... Are provided at the four corners of the openings on the long sides of the bottom plate 32 and the top plate 33, and the rotor housing 30 is fixedly inserted through these bolt holes 38, 38,. By tightening the bolts 39, 39 (see FIG. 2), they are correctly aligned with the rectangular openings formed in the housing 3 and sealed and fixed. Due to this fixation, the magnetic head 12 fixed to the tip of the carriage 11 of the rotor 1 extends inside the housing 3 and faces the recording surface of the magnetic disk 4 with a predetermined gap therebetween, and is generated around the pivot 10. The rotor 1 is moved in the radial direction by swinging, and a predetermined position on the recording surface is accessed by a synergistic effect with the rotation of the magnetic disk 4 to read information recorded at the position or record information at the position. The information to be written is written.

FIG. 4 is an exploded perspective view of the stator housing 31. The stator housing 31 includes an inner yoke 22 and an outer yoke 23. The outer yoke 23 has an outer surface formed by notching an intersection of two substantially orthogonal straight lines with an appropriate width,
A main body portion 24 having a predetermined length having a cross-sectional shape as shown in FIG. 2 having an inner surface formed by connecting short linear portions along the two straight lines of the outer surface to both sides of the circular arc. Roof portions 25, 25 projecting substantially orthogonally to both ends in the longitudinal direction of the rotor housing 30. Both side edges of the main body portion 24 and edges of the roof portions 25, 25 align with the opening on the short side of the rotor housing 30. The inner yoke 22 has a pair of connecting projections 26, 26 extending radially outward on both side edges of a notched cylinder having a quarter-circle cross section of an appropriate thickness. The connecting projections 26, 26 of the inner yoke 22
Along the inner side edge of the outer yoke 23, and a pair of set screws
The stator housing 31 is constituted by being integrally joined at 27 and 27.

The outer surface of the inner yoke 22 and the inner surface of the outer yoke 23 which are opposed to each other by the above-mentioned coupling have a pair of magnets each having an arc-shaped cross section and having mutually different magnetic poles in the thickness direction.
The magnets 20 and 21 are arranged side by side in the circumferential direction such that the magnets 20 and 21 of the inner yoke 22 and the magnets 21 and 20 of the outer yoke 23 face each other. With this configuration, the magnetic circuit between the magnets 20 and 21 is formed not only in the inner yoke 22 and the outer yoke 23 but also in the two yokes 22 and 23.
Are also formed in the connecting projections 26, 26 connecting the
A sufficient magnetic flux density can be secured between 20, 21 and both yokes 22, 23
Can be made thinner.

The stator housing configured as described above
Numeral 31 is provided at the opening of the rotor yoke 23 in front of the outer yoke 23 at the short side opening of the rotor housing 30 fixed to the housing 3 for accommodating the magnetic disk 4 as described above, and protrudes as described above. In the through holes 37, 37 formed in the fixing flanges 36, 36, the connection protrusions 26,
Align the screw holes 28, 28 formed outside the base end of 26,
One set screw 29, 29 (see FIG. 2) inserted into the former is screwed into the latter and fixed.

The drive coil 14 of the rotor 1 pivotally supported by the rotor housing 30 by this fixation is concentrically interposed between the inner yoke 22 and the outer yoke 23 as shown in FIG. The rotor 1 is located in the magnetic circuit formed as described above, and in this state, when the drive coil 14 is energized, the rotor 1 swings around the pivot 10 with the acceleration determined by the above equation (1). And the magnetic head 10 at the tip of the carriage 11
Is accessed at a predetermined position on the recording surface of the magnetic disk 4. A packing 5 is interposed between the outer peripheral edge of the outer yoke 23 and the rotor housing 30 as shown in FIG. 2, and the sealing between the rotor housing 30 and the stator housing 31 is performed by the action of the packing 5. The state is ensured.

As described above, in the present invention, the stator housing 31 fixed to the outside of the rotor housing 30 is
Since the outer yoke 23, which is a component of the magnets 20, 21 inside the outer yoke 23, can be disposed along the outer wall of the housing 3, as shown in FIG. The rotation radius r ₁ of the drive coil 14 close to
The magnetic head 12 can be made as large as possible within a predetermined space limited by an extension of the outer wall of the housing 3, in other words, within a limited plane space of the entire magnetic disk drive.
Can be designed to have a large ratio with respect to the turning radius r _0, so that the acceleration constant Kα determined by the equation (1) increases,
High-speed access with high responsiveness becomes possible.

Further, since the outer yoke 23 is in contact with the outside air, the heat generated by the drive coil 14 is dissipated to the outside air, and when reading or writing by the magnetic head 12, reliability due to the effect of the generated heat is increased. The deterioration of the sex is effectively mitigated.

[0026]

As described above, in the magnetic head actuator according to the present invention, the radius of rotation of the drive coil can be designed to be as large as possible within a limited plane space.
The large acceleration obtained thereby enables high-speed access with high responsiveness. Further, the heat generated by the drive coil due to the repetition of the access is effectively dissipated through the outer yoke exposed to the outside, so that a decrease in reliability due to the influence of the heat can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a part of a magnetic disk drive provided with a magnetic head actuator according to the present invention in a cutaway manner.

FIG. 2 is a plan view showing a main part of a magnetic disk drive provided with a magnetic head actuator of the present invention.

FIG. 3 is a perspective view of a rotor housing.

FIG. 4 is an exploded perspective view of a stator housing.

FIG. 5 is a plan view showing a main part of a magnetic disk drive provided with a conventional magnetic head actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 3 Housing 4 Magnetic disk 5 Packing 10 Axis 12 Magnetic head 14 Drive coil 20 Magnet 21 Magnet 22 Inner yoke 23 Outer yoke 24 Main body 25 Roof 30 Rotor housing 31 Stator housing

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-277458 (JP, A) JP-A-3-86054 (JP, A) JP-A-62-133262 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) G11B 21/02 H02K 33/18

Claims (3)

(57) [Claims] 1. A box-shaped housing (3) for accommodating a magnetic disk (4), which is formed at one corner of a box-shaped housing (3) and swings around a pivot (10) parallel to a rotation axis of the magnetic disk (4). A rotor (1) for moving a magnetic head (12) attached to one end protruding along the recording surface of the magnetic disk (4), and a rotor (1) protruding to the other side. A pair of magnets (20) and (21) having an arc-shaped cross-section centered on the pivot (10) are respectively opposed to the outside of the drive coil (14) fixed to the portion, and each of the magnets has a magnetic circuit. In a moving coil type magnetic head actuator comprising an inner yoke (22) and an outer yoke (23), the rotor (1) is sealed and fixed in an opening formed by cutting out a corner of the housing (3). ) Via the pivot (10) and a rotor housing (30) Is fixed to the outside of the rotor housing (30), a magnetic head actuator, characterized by comprising a stator housing (31) to the peripheral wall of said outer yoke (23). 2. The inner yoke (22) is provided on both sides of an arc-shaped inner surface centered on a pivot (10).
(24) and a roof (2) projecting at almost both ends in the longitudinal direction substantially perpendicular to the longitudinal direction.
5) and (25), wherein an edge of the roof (25), (25) and an edge of the main body (24) constitute a sealing edge to the rotor housing (30). 2. The magnetic head actuator according to 1. 3. The magnetic head actuator according to claim 1, wherein the rotor housing (30) has openings on both sides thereof having sealing edges around the housing (3) and the stator housing (31).