JPH04134765A - Head positioning mechanism for magnetic disk medium - Google Patents

Abstract

PURPOSE:To reduce the amount of thermal off-track and execute an accurate positioning of a magnetic head by adding a radial weight to the upper and lower bearing outer rings, and using bearing outer rings with different material from each other and upper and lower rings in contact therewith. CONSTITUTION:The material of upper and lower rings 3, 9 being respectively in contact with the outer rings of upper and lower bearings 4, 11 which support both ends of a shaft 5 which fixes an arm holder 10 are made different from each other. The outer ring of the lower bearing 11 has the radial weight added by a spring 9 of a coma 12, thus to enter into contact to the ring 9, and in the same way to the outer rings of the upper bearing 4, has the radial weight added, and enters into contact to the ring 3. Then, the thermal expansion coefficient of the upper ring 3 and the lower ring 9 are different, and the shaft 5 can be inclined in accordance with temperature change. Thus, the thermal off-track amount becomes small, and the accurate positioning of the magnetic head can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a head positioning mechanism for a magnetic disk medium, and particularly to a structure for applying preload to a bearing.

[Conventional technology]

Positioning mechanisms for magnetic disk drives can be broadly classified into linear types and rotary types, and the latter type is generally adopted in small or medium capacity magnetic disk drives. Furthermore, in order to increase the recording density and storage capacity of a magnetic disk device, it is necessary to improve the positioning accuracy of the magnetic head with respect to the magnetic disk medium.

The positioning mechanism of the magnetic head in current magnetic disk drives has a servo head dedicated to positioning, and this servo head reads positioning information recorded in advance on the surface of the magnetic disk medium, and performs positioning based on the read information. There is.

Therefore, the relative displacement amount between the servo head and other data heads and the relative displacement amount between the servo disk medium on which positioning information is written and the other data disk medium are the deviations from the track that should originally be followed. amount, that is, the amount of off-track. The smaller the off-track amount, the higher the positioning accuracy.

However, in reality, an amount of off-track that is more than permissible may occur due to various factors. Of this amount of off-track, off-track caused by a temperature rise in the magnetic disk drive or a change in environmental temperature is called thermal off-track, and is caused by differences in linear expansion coefficients between the various mechanical parts that make up the magnetic disk drive. considered to be the main factor.

Here, the conventional rotary head positioning mechanism mentioned above is shown in FIG. In the figure, reference numeral 10 denotes an arm holder, in which arms 2 on which magnetic heads 1 are mounted are stacked and held. This arm holder 1o is fixed to a shaft 5, and the shaft 5 is held on a base plate 13a via two upper and lower bearings 4 and 11. Further, the magnetic head 1 is driven by a coil 8 attached to the arm holder 10 and a magnetic circuit 7 fixed to the base plate 130 with a fixed vertical gap between the coil 8 and the coil 8. The shaft 5 and the inner rings of the upper and lower bearings 4.11 are fixed with adhesive, and the outer rings are fixed to the base plate 13a.
A spring 6 and a piece 12 are inserted into a U-shaped groove provided in the bearings 4 and 11, and are pressed against the bearings 4 and 11 in the radial direction. This eliminates backlash due to the difference in thermal expansion between the bearings 4, 11 and the base plate 13a due to temperature rise, and reduces the amount of thermal off-track.

[Problem to be solved by the invention]

As mentioned above, thermal off-track is the amount of relative displacement between the magnetic disk medium and the magnetic head due to temperature changes. If the head is also tilted in the same way, the relative displacement will be smaller = However, in the conventional magnetic disk head positioning mechanism mentioned above, the arm holder that supports the magnetic head does not tilt due to temperature changes. The amount of displacement caused by the tilting of the spindle supporting the magnetic disk medium directly becomes the amount of thermal off-track. In addition, when the base plate that holds both ends of the shaft deforms due to temperature changes, the conventional head positioning mechanism for magnetic disk media will deform the arm holder and the arm holder held on the shaft when the shaft tilts due to the deformation of the base plate. The disadvantage is that the magnetic head also tilts, causing thermal off-track.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head positioning mechanism for a magnetic disk device that can eliminate the above-mentioned drawbacks, reduce the amount of thermal off-track, and accurately position a magnetic head.

[Means to solve the problem]

The present invention provides a magnetic head that records/reproduces information facing a predetermined track of a magnetic disk medium, an arm holder that supports the magnetic head via an arm, a shaft that holds the arm holder, and a shaft that supports the arm holder. A coil fixed to the arm holder, a magnetic circuit that applies rotational force to the arm holder through magnetic coupling with the coil, two bearings that support both ends of the shaft, and a spring that applies a radial load to each of the bearings. and a head positioning mechanism for a magnetic disk medium comprising the two bearings and a base plate holding the spring, wherein members of the outer rings of the two bearings that come into contact are made of different materials.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention. In FIG. 1, the head positioning mechanism for a magnetic disk medium of the present invention includes an arm 2 on which a magnetic head L is mounted facing a magnetic disk medium (not shown), and an arm holder 10 that fixedly supports the arm 2. and a shaft 5 to which the arm holder 10 is adhesively fixed, a base plate 13 which holds both ends of this shaft 5 via upper and lower bearings 4 and 11 and a ring 3.9, and a ring 3.9. Bearing 4.11 via spring 6 in the U-shaped groove
The magnetic head 1 has a top 12 that presses the outer ring in the radial direction, and a magnetic circuit 7 that drives the magnetic head 1. The difference from the conventional example is that the materials of the upper and lower rings 3.9 that contact the outer rings of the upper and lower bearings 4.11 are different from each other. The outer ring of bearing 11 on the lower side is piece 1
A radial load is applied by the ring 2 and the spring 6, and the ring 9 is in contact with the ring 9. On the other hand, the outer ring of the upper bearing 4 is subjected to a radial load by the piece 12 and the spring 6, and is in contact with the ring 3. Therefore, since the upper ring 3 and the lower ring 9 are made of different materials, they have different thermal expansion coefficients and can tilt the shaft 5 against temperature changes.

Thus, when the spindle holding the magnetic disk medium is tilted due to temperature changes, the amount of thermal off-track can be reduced by tilting the shaft 5 in the same direction as the tilt. Furthermore, when the base plate 13 deforms due to temperature changes, it becomes possible to correct the shaft 5 so that it does not tilt due to this deformation, and the amount of thermal off-track can be reduced.

〔Effect of the invention〕

As explained above, the head positioning mechanism of the magnetic disk drive of the present invention applies a radial load to the upper and lower bearing outer rings, and also uses the bearing outer rings made of different materials and the upper and lower rings in contact with the outer rings, thereby achieving thermal This has the effect of reducing the off-track amount and allowing accurate positioning of the magnetic head.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional head positioning mechanism for a magnetic disk medium. 1...Magnetic head, 2...Arm, 3.9...Ring, 4...Bearing, 5...Shaft, 6...
・Spring, 7... Magnetic circuit, 8... Coil, 1
0...Arm holder, 11...Bearing, 12.
...Frame, 13.13a...Base plate.

Claims (1)

[Claims] A magnetic head that records/reproduces information facing a predetermined track of a magnetic disk medium, an arm holder that supports the magnetic head via an arm, a shaft that holds the arm holder, and a shaft that is fixed to the arm holder. a magnetic circuit that applies rotational force to the arm holder through magnetic coupling with the coil; two bearings that support both ends of the shaft; and a spring that applies a radial load to each of the bearings; A head positioning mechanism for a magnetic disk medium comprising two bearings and a base plate holding the spring, wherein members that contact the outer rings of the two bearings are made of different materials. .