JPH03260964A - Head actuator for magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent thermal deformation and to reduce the position error of a magnetic head by fixing a stator yoke on a housing by using a thermal deformation relaxing means. CONSTITUTION:The recessed part 38 of the housing 37 is formed almost in semi-cylindrical shape, and a stator yoke mounting hole is provided in the center of a plane (c) at the most depth part, and the stator yoke 39 can be fixed by inserting a screw 42 to the hole. Also, another part is set in a light press fitting state by utilizing the elasticity of the semi-cylindrical yoke 39. In such a way, since the spring constant of the yoke 39 is lower than that of the housing 37, no thermal deformation in the housing 37 occurs even when temperature change occurs.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a head actuator in a magnetic disk device widely used as a file storage device in information systems, and is capable of preventing thermal deformation and reducing positioning errors of the magnetic head. and for the purpose of improving assemblability, it is equipped with a plurality of magnetic heads and an arm rotor assembly for supporting and positioning the magnetic heads, a permanent magnet is provided in the rotor of the arm rotor assembly, and a stator yoke is provided on the stator side. and a coil, wherein the stator has an aluminum housing having a semi-cylindrical recess, and a partially cut-out ring (1) or (2)-shaped ring is provided in the recess of the housing. A stator yoke is housed therein, and a thermal deformation mitigation means is provided between the stator yoke and the housing.

Further, means for fixing the fixed shaft of the rotor is installed on the upper and lower surfaces of the recessed portion of the housing, and the fixed shaft is configured to be attached from the front surface of the opening of the recessed portion of the housing.

[Industrial application field]

The present invention relates to a head actuator in a magnetic disk device widely used as a file storage device in information systems.

In recent years, the density of magnetic disk drives has been significantly increased, and the track pitch is becoming on the order of 10/-.

Therefore, in the head positioning system, it is necessary to reduce head position deviation (off-track) due to temperature changes. At the same time, it is also important to increase the rigidity of the actuator system in order to quickly and accurately position the device after high-speed access.

[Conventional technology]

In order to increase the rigidity of the actuator system, a moving magnet type actuator has been proposed in place of the generally widely used VCM (voice coil motor; moving coil type). (For example, [l5P4346416, patent application No. 6
3-203090) FIG. 4 is a diagram showing a magnetic disk device using a movable magnet type actuator, in which (a) is a top view and (b) is a perspective view of the main part. In this method, a plurality of magnetic disks 2 are fixed to a spindle l at predetermined intervals, and a magnetic head 3 for writing or reading data on tracks on both sides of each magnetic disk 2 is attached to a head assembly 4. The assembly 4 is attached to an arm carriage assembly 5, and the arm carriage assembly 5 is configured to be rotatable by a motor 6 within the range indicated by the dashed line in FIG.
The magnetic head 3 is rotated 600 times, and the motor 6 is controlled to position the magnetic head 3 at a commanded track position. The magnetic head positioning mold (3) (4) - The block 6 includes a rotor 7 at the end of the arm carriage assembly 5, and a semicircular stator 8 disposed at a predetermined distance from the rotor 7. It is called a rotating type or a swinging type.

FIG. 5 is a diagram showing a rotary actuator, (a)
is a top view, and (b) is an exploded perspective view. In the figure, the rotor 7 includes a rotor yoke (not shown) to which permanent magnets 9, 10, and 11 are fixed, and a rotating shaft 13 for rotatably supporting the rotor 7.
．． 14, and the stator 8 includes a stator yoke 15, a coil 16, 17, an upper cover 18, and a bearing part 19, 20.
and a bolt 21.

The permanent magnets 9, 10 and 11 of the rotor 7 can be made of rare earth magnets such as anti-magnets and neodymium iron magnets with large residual magnetic flux density, and the permanent magnets 9, 11 on both sides
In contrast, the width of the intermediate permanent magnet 10 is widened (in the radial direction and thickness direction, respectively) so that N and S magnetic poles are arranged alternately along the circumferential direction. The rotor is fixed via the rotor yoke within approximately a half-circumference of the rotor's outer circumference.

Further, an arm carriage assembly 5 is attached to this rotor 7, and a head assembly 4 is attached to the arm carriage assembly 5, as shown in FIG. 5(b).
In the figures, illustration of the head assembly 4 is omitted for the sake of simplification.

Further, the rotor 7 is rotatably supported by bearings 19 and 20 of the stator 8 via a rotating shaft 13,14.

The stator yoke 15 of the stator 8 is fan-shaped, and two concentric coils 16 and 17 are fixed to its inner peripheral surface, and the coils 16 and 17 have opposite polarities from a drive circuit (not shown). It is excited like this. Coil 1
6. Permanent magnets 9 and 10° 11 facing 17 are attracted,
The rotor 7 rotates due to the repulsion, and the magnetic head 3
will be positioned on the commanded track.

[Problem to be solved by the invention]

The conventional actuator described above requires an external stator yoke due to its structure. Magnetic disks are generally made of aluminum-based materials, so to avoid thermal deformation due to temperature changes, the bases (5) and (6) of disk drives are made of aluminum-based materials. If the stator 15 of the actuator shown in FIG. 5 is attached directly to the aluminum base, thermal deformation cannot be avoided, and the stator 15 of the actuator shown in FIG. 5 cannot be used, especially when the track density is increased as in recent years.

SUMMARY OF THE INVENTION In view of the above conventional problems, an object of the present invention is to provide a head actuator for a magnetic disk device that prevents thermal deformation of a housing, reduces positioning errors of a magnetic head, and improves ease of assembly. .

[Means to solve the problem]

In order to achieve the above object, a head actuator for a magnetic disk drive according to the present invention includes a plurality of magnetic heads 31 and an arm rotor assembly 30 that supports and positions the magnetic heads 31, and a rotor of the arm rotor assembly. 3
4 is equipped with a permanent magnet 35, and a stator yoke 3 is installed on the stake side.
9 and a coil 44, the stake has an aluminum housing 37 having a semi-cylindrical recess 38, and the recess 38 of the housing 37
A ring-shaped stator yoke 39 with a portion cut out is housed in the stator yoke 39, and a thermal deformation mitigation means is provided between the stator yoke 39 and the housing 37.

Further, the rotor 3 is provided on the upper and lower surfaces of the recess 38 of the housing 37.
installing means for fixing the fixing shaft 36 of No. 4;
It is characterized in that the fixed shaft 36 is attached from the front surface of the opening of the recess N3B of the housing 37.

[For production]

By fixing the iron-based stator yoke 39 to the aluminum-based housing 37 using thermal deformation mitigation means, thermal deformation of the housing 37 can be prevented, and positioning errors of the magnetic head can be reduced. Furthermore, the fixing means for the fixed shaft 36 is provided on the upper and lower surfaces of the housing 37, and the fixed shaft 36 can be attached from the front surface of the opening of the recessed portion of the housing, thereby improving assembly efficiency.

(7) (8) [Embodiment] Fig. 1 is a diagram showing an embodiment of the present invention, in which (a) is an exploded perspective view, and (b) is an exploded view of a cross section taken along line bb in figure a. be.

In FIG. 1(a), 30 is an arm rotor assembly that supports and positions the magnetic head 31, and the arm rotor assembly includes a head assembly 32, an arm carriage assembly 33, a rotor 34, and a rotor yoke. 34
It is composed of a permanent magnet 35 for driving a1, a fixed shaft 36, etc. Reference numeral 37 denotes a stator housing that is attached to a cutout of one corner of the rectangular base of the magnetic disk device, and the housing has a substantially triangular prism shape with a semi-cylindrical recess 38 for accommodating the stator yoke. The recess 38 accommodates a partially cut-out ring-shaped stator yoke 39, and the fixed shaft of the arm rotor assembly 30 is mounted on the upper and lower surfaces of the recess 38. Shaft support 40 for supporting and fixing 36.
40' is attached.

(b) As shown in the figure, the concave portion 38 of the housing 37 is approximately semi-cylindrical, but in consideration of workability, three surfaces, namely both sides a and b, and the innermost portion C, are made flat, and the innermost portion is a flat surface C. A stator yoke mounting hole 41 is provided in the center of the stator yoke, and a screw 42 is inserted into the hole 41.
is inserted to fix the stator yoke 39. The other parts are lightly press-fitted by utilizing the elasticity of the semi-cylindrical yoke. Also, use soft adhesive to fill the gap between the surfaces A and C and between the surfaces C and the housing 37.
The stator yoke may be glued to. Note that 43 is a screw hole for attaching the stator yoke, and 44 is a coil bonded to the stator yoke.

Figure 2(a) shows the 1st r! ! 211(b) is an enlarged view of the fixed shaft support portion of the shaft support.

In FIG. 2(a), 40.40' is a shaft support, and this shaft support 40.40' has a reference protrusion g45, and shaft support mounting reference holes 46 provided on the upper and lower sides of the housing 37. It is fitted, positioned and fixed. Also this shaft support) 40.4
As shown in FIG. 3 (9> (10)), the fixed shaft support part 0' is positioned by contacting the fixed shaft 36 at two contact points formed by three circular arcs a, b, and c. As shown in FIG. 1(a), the fixed shaft 36 is inserted through the opening of the recess of the housing 37, and is screwed to the shaft support 40, 40' with a screw 47.

In this embodiment configured as described above, the semi-cylindrical stator yoke 39 is inserted into the recess 3 of the housing 37 by utilizing its elasticity.
The stator yoke 39 is inserted into the stator yoke 8 with a slight press fit and fixed with a single screw 42, so even if the temperature changes, the stator yoke 39
Since the spring constant of the housing 37 is lower than that of the housing 37, the housing 37 does not undergo thermal deformation. Also, the shaft support 40.40' determines the center of rotation of the actuator.
are a pair of upper and lower parts, and are positioned by the reference hole 46 of the housing 37, and the shaft fixing portion is in two-point contact, so that the fixed shaft 36 can be fixed accurately and stably. Furthermore, the assembly is performed using the recess 38 of the housing 37.
Assembly is easy because it can be done from the opening surface.

〔Effect of the invention〕

As described above, the present invention provides a head actuator that allows for more accurate head positioning without causing almost any thermal deformation even when an iron-based stator yoke is incorporated into an aluminum-based housing. be able to. Further, it is possible to provide a head actuator in which the stator yoke and the fixed shaft of the arm rotor assembly can be easily fixed to the housing.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line a-a in Fig. 1(a), Fig. 3 is an enlarged view of the fixed shaft support part of the shaft support, and Fig. 4 is A diagram showing a magnetic disk device using a conventional rotary actuator. FIG. 5 is a diagram showing a conventional rotary actuator. In the figures, 30 is an arm rotor assembly, 31 is a magnetic head, 32 is a head assembly, 33 is an arm carriage assembly, 34 is a rotor, 35 is a permanent magnet, 36 is a fixed shaft, 37 is a housing , 38 is a recess, 39 is a stator yoke, 40, 40' is a shaft support, 41 is a stator yoke mounting hole, 42.47 is a screw, 43 is a screw hole, 44 is a coil, 45 is a protrusion, 46 is a reference hole shows. (13) ellipse C) FN V'r dimension □6y ~ dimension (a) 0
0 (I) (I) 00 (I) (I) Dimension Dimension Dimension 484-

Claims (1)

[Claims] 1. A plurality of magnetic heads (31) and the magnetic heads (31)
), a rotor (34) of the arm rotor assembly is provided with a permanent magnet (35), and a stator yoke (3) is provided on the stator side.
9) and a coil (44), the stator has an aluminum housing (37) having a semi-cylindrical recess (38), and the housing (37)
A partially cut-out ring-shaped stator yoke (39) is accommodated in the recess (38), and a thermal deformation mitigation means is provided between the stator yoke (39) and the housing (37). Features of head actuators for magnetic disk drives. 2. In the head actuator for a magnetic disk drive according to claim 1, means for fixing the fixed shaft (36) of the rotor (34) are installed on the upper and lower surfaces of the recess (38) of the housing (37), and A head actuator for a magnetic disk drive, characterized in that a fixed shaft (36) is attached from the front surface of an opening of a recess (38) in a housing (37).