JPH0775100B2 - Magnetic disk unit - Google Patents

Abstract

PURPOSE:To diminish an off-track amt. in a wide range of temperature by providing an energizing means for energizing a bearing in the vicinity of a fitting hole for the bearing and providing also two separated protrusion parts on the inner wall of the hole. CONSTITUTION:Both end parts of a spindle 21 fitted with a magnetic disk and a shaft 22 of an actuator for moving a head to an objective track are fitted rotatively to a housing via bearings 23 and 24 and bushes 25 and 26. In this constitution, at least either of the bearing 23 for the spindle 21 or the bearing for an actuator shaft 22 is energized by energizing means 27 and 28 in the direction of correcting an off-track. Then, when the temperature is raised, a distance between the protrusion parts 25b and 25c or 26b and 26b provided separately on the inner wall of the bearing fitting hole 25a or 26a is expanded, so that a pivot distance between the spindle 21 and the shaft 22 is increased. By this method, the off-track amt. is suppressed to a minimum in a wide range of temperature.

Description

DETAILED DESCRIPTION [Outline] A spindle shaft to which a magnetic disk is attached, an actuator shaft for moving a head for writing / reading data to / from a magnetic disk to a target track, and a spindle shaft or an actuator shaft. An object of the present invention is to provide a magnetic disk device in which both ends of at least one member are rotatably attached to a housing via bearings, and the off-track amount can be suppressed to a small value in a wide temperature range. A bearing mounting hole for loosely fitting the bearing,
A bushing that rotatably supports both ends of at least one member of the spindle shaft or the actuator shaft to the housing via the bearing, and a direction parallel to a straight line connecting the spindle shaft and the actuator shaft. And a biasing means for biasing the bearing.

[Field of Industrial Application] The present invention relates to a spindle shaft to which a magnetic disk is attached, an actuator shaft for moving a head for writing / reading data to / from a magnetic disk to a target track, a spindle shaft or an actuator. The present invention relates to a magnetic disk device in which both ends of at least one member of a shaft are rotatably attached to a housing via bearings.

In such a magnetic disk device, it is desired that the off-track caused by the temperature rise of the device under operation does not occur.

[Prior Art] Next, a conventional example will be described with reference to the drawings. FIG. 5 is a block diagram of a conventional magnetic disk device.

In the figure, 1 is a housing for enclosing a magnetic disk device, and 2 is a spindle drive motor attached to the housing 1. A spindle shaft 3 (hereinafter, this spindle shaft is simply referred to as a spindle) 3 is attached to a rotor (not shown) of the spindle drive motor 2. A spindle hub 4 is fixed to the spindle 3, and five disks 5 are stacked on the spindle hub 4 in the conventional example. The spindle 3 has a housing 1 through bearings 6 and 7 mounted on both ends of the spindle 3 and bushes 8 and 9 for holding the bearings 6 and 7.
Is rotatably attached to. Then, these disks 5 are rotated at a constant speed (for example, 3600 rpm) by the drive of the spindle drive motor 2.

Next, the actuator will be described. Numeral 10 is a head provided on each disk surface of the disk 5 for writing / reading data to / from each disk 5, and these heads 10 are attached to a head arm 12 via a gimbal spring 11. The head arms 12 are laminated and integrated via a spacer 13. An actuator shaft (hereinafter, this actuator shaft is simply referred to as a shaft) 14 is attached to the head arm 12 thus integrated. The shaft 14 is rotatably attached to the housing 1 via bearings 15 and 16 attached to both ends and bushes 17 and 18 holding the bearings 15 and 16. Reference numeral 19 is a voice coil motor to which the lower end of the shaft 14 is connected and which drives the actuator to swing.

Next, the operation of the above configuration will be described. When a control circuit (not shown) supplies a current to the voice coil motor 19, the integrated head arm 12 swings (rotates) around the shaft 14.
By swinging the integrated head arm 12, each head 10 accesses a target track on each disk 5.

[Problems to be Solved by the Invention] In the magnetic disk device having the above-mentioned configuration, when the temperature state is different between the time of writing data and the time of reading data, there is a problem that so-called off-track becomes unreadable.

The cause of the off-track is that the temperature of the housing 1 itself is lower than the temperature of the inside of the housing 1 and the distance between the pivots between the spindle 3 and the shaft 14 does not sufficiently extend.

FIG. 6 is a diagram showing the relationship between the device temperature and the off-track amount in FIG. In the figure, the plot (x) shows the case where the device is in a stable temperature state (ambient atmosphere + heat generated by the device itself), and the plot (○) shows the case where the device is in an unstable temperature state immediately after starting up. Is shown. As can be seen from this figure, when the data written at 0 ° C. reaches a device temperature of about 60 ° C., the off-track amount becomes large and the data becomes unreadable. In particular, this phenomenon is due to dual heads (one with two heads per disk)
This occurs in the head row that does not have the servo head.

The present invention has been made in view of the above problems, and an object thereof is to provide a magnetic disk device capable of suppressing the off-track amount to be small in a wide temperature range.

[Means for Solving the Problems] FIG. 1 is a principle view of the present invention.

In the figure, 21 is a spindle shaft to which a magnetic disk is attached (hereinafter, this spindle shaft is also simply referred to as a spindle), and 22 is a head for writing / reading data to / from the magnetic disk to a target track. The actuator shaft (hereinafter, this actuator shaft is also simply referred to as a shaft). Both ends of the spindle 21 and the shaft 22 are rotatably attached to the housing via bearings 23 and 24 and bushes 25 and 26. Of the bearing mounting hole 25a of the bush 25 for spindle and the bearing mounting hole 26a of the bush 26 for shaft of the actuator,
At least one bearing mounting hole 25a, 26a
In the vicinity of (both cases are illustrated in this figure), the bearings 23 and 24 are urged in a direction parallel to the straight line connecting the spindle 21 and the shaft 22 as shown in FIG. Means 27, 28 are provided. In addition, in FIG. 1, two protrusions spaced apart in the circumferential direction are provided on the inner wall of each bearing mounting hole 25a, 26a with which the bearing 23, 24 biased by the biasing means 27, 28 presses. It is shown. That is, 25b, 25c and 26b, 26c are bearing mounting holes 25a, 26c.
Bearings 23 and 24, which are urged by urging means 27 and 28, are pressed against the inner wall of a by two protrusions provided so as to be spaced apart in the circumferential direction.

[Operation] In the magnetic disk device shown in FIG.
At least one of the bearing 23 and the bearing 24 of the shaft 22 of the actuator is biased by a biasing means in a direction parallel to a straight line connecting the spindle 21 and the shaft 22. Then, when the temperature rises or falls, the intervals between the protrusions 25b and 25c and the intervals between the protrusions 26b and 26c increase or decrease, and the intervals between the protrusions 25b and 25c and the protrusion 2 change.
The spindle 21 and the shaft 22 further move in and out between 6b and 26c, and the distance between the pivots of the spindle 21 and the shaft 22 increases or decreases so as to correct off-track.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. Second
FIG. 4 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is a diagram for explaining the mounting of bushes and bearings in FIG. 2, and FIG. 4 is a relation between the apparatus temperature and the off-track amount in FIG. It is a figure.

In the figure, 31 is a housing for enclosing the magnetic disk device, and 32 is a spindle drive motor attached to the housing 31. 33 is a spindle shaft (hereinafter, this spindle shaft is also simply referred to as a spindle)
Is attached to the rotor (not shown) of the spindle drive motor 32. A spindle hub 34 is fixed to the spindle 33, and five disks 35 are stacked on the spindle hub 34 in this embodiment. The spindle 33 has bearings 36 and 37 mounted on both ends and bearings 36 and 37.
Is rotatably attached to the housing 31 via bushes 38, 39 for holding the. And these discs 35
Is driven by a spindle drive motor 32 to rotate at a constant speed (for example, 3600 rpm).

Next, the actuator will be described. Numeral 40 is a head provided on each disk surface of the disk 35 and writing / reading data to / from each disk 35. These heads 40 are attached to a head arm 42 via a gimbal spring 41. The head arms 42 are laminated and integrated via a spacer 43. An actuator shaft (hereinafter, also referred to simply as the shaft) 44 is attached to the head arm 42 thus integrated. This shaft 44 has bearings 45,4 attached to both ends of this shaft 44.
It is rotatably attached to the housing 31 via bushes 47 and 48 that hold 6 and bearings 45 and 46. Reference numeral 49 is a voice coil motor to which the lower end of the shaft 44 is connected and which drives the actuator to swing.

Next, a mounting structure of the bush and the bearing will be described with reference to FIG. Reference numerals 39a and 48a are bearing mounting holes for the bush 39 for the spindle and the bush 48 for the shaft of the actuator, which are formed so that the bearings 37, 46 are loosely fitted. 50 and 51 are provided in the bearing mounting holes 39a and 48a, and the bearings 37 and 46 are attached to the spindle 3 as shown in FIG.
A leaf spring that urges in a direction parallel to a straight line connecting the shaft 3 and the shaft 44. Reference numerals 39b and 39c are two protrusions against which the bearing 37 urged by the leaf spring 50 is pressed, and bearing mounting holes are provided.
It is provided on the inner wall of 39a. 48b and 48c are also leaf springs 51
The bearing 46 is urged by the bearing to press it.

Although the bearing 37, the bush 39, the bearing 46, and the bush 48 are described in FIG. 3, the bearing 36, the bush 38, the bearing 45, and the bush 47 have the same configuration, and the leaf springs 52, 53 are the same. Is provided.

Next, the operation of the above configuration will be described. When a control circuit (not shown) supplies a current to the voice coil motor 49, the integrated head arm 42 swings (rotates) around the shaft 44.
By swinging the integrated head arm 42, each head 40 accesses a target track on each disk 35.

According to the above configuration, the off-track amount can be reduced even if the temperature of the housing 31 itself is lower than the temperature inside the housing 31. In particular, when the protrusions 39b, 39c and the protrusions 48b, 48c are provided as in the above configuration, the protrusions 39b, 39c due to the temperature rise
The distance between b, 39c and the protrusions 48b, 48c also increases, and the spindle 33 and the shaft 44 further enter between the enlarged protrusions 39b, 39c and between the protrusions 48b, 48c, whereby the spindle 33 and the shaft 44 The distance between the pivots can be increased more than the extension of the housing 31 itself, and the off-track amount can be further reduced. The change in the distance between the pivots of the spindle 33 and the shaft 44 will be described below with reference to FIG.

In FIG. 3, when the temperature rises by Δt ° C., the new inter-pivot distance changes from L (before temperature rise) to L ″ shown in the following equation.

L ″ = L ′ + T _s ′ + T _a ′, where L ′ = L (1 + α _B Δt) φ _s1 ′ = φ _s1 (1 + α _s Δt) φ _s2 ′ = φ _s2 (1 + α _A Δt) φ _a1 ′ = φ _a1 (1 + α _s Δt) φ _a2 ′ = φ _a2 (1 + α _A Δt) B _s ′ = B _s (1 + α _A Δt) B _a ′ = B _a (1 + α _A Δt) α _s … Linear expansion coefficient of bearings 37,46 α _A … Linear expansion coefficient of bushes 39,48 α _B … Linear expansion coefficient of housing 31 φ _s1 … Outer diameter of bearing 37 (before temperature rise) φ _s2 … Inner diameter of bearing mounting hole 39a (before temperature rise) φ _a1 … Outer diameter of bearing 46 (before temperature rise) φ _a2 … Inner diameter of bearing mounting hole 48a (before temperature rise) ) B _s : Distance between protrusions 39b, 39c (before temperature rise) B _a : Distance between protrusions 48b, 48c (before temperature rise) In the magnetic disk device with the conventional configuration, the bearing mounting holes 39a, 48a are the bearings 37, The bearings 37 and 46 are formed so that they cannot be loosely fitted.
It is fixed in a and 48a. Therefore, the inter-pivot distance when the temperature rises by Δt ° C. is equal to the elongation of the housing 31 itself and is represented by L ′ = L (1 + α _B Δt).

Therefore, when the protrusions 39b, 39c and the protrusions 48b, 48c are provided as in the above-described embodiment of the present invention, the protrusion 39 is increased when the temperature rises.
The intervals between b and 39c and between the protrusions 48b and 48c widen, and the spindle 33 and the shaft 44 further enter between the expanded protrusions 39b and 39c and between the protrusions 48b and 48c, respectively. And the distance between the pivot of shaft 44 and housing 31
The amount of off-track can be further reduced because it increases more than the elongation of itself. That is, even if the temperature rises the same, the distance between the pivots is T _s ′ + T _a ′ rather than the elongation of the housing 31 itself.
Over a wide temperature range (in other words, the housing 31 with respect to the inside of the housing 31
The amount of off-track can be reduced (even when the temperature difference between 31 itself is large). FIG. 4 is a diagram showing the relationship between the device temperature and the off-track amount when such a configuration is adopted. As you can see from this figure, the off-track amount becomes smaller,
Even if the device temperature reaches about 60 ℃, the data written at 0 ℃ will not be unreadable.

The present invention is not limited to the above embodiment. For example,
In the above-mentioned embodiment, the leaf spring as the urging means is the spindle 33.
Side is provided on the side of the actuator and the shaft 44 side of the actuator, but only one of them may be provided. Also, as a biasing means, a bush
Although the leaf springs 50 and 51 are provided in the bearing mounting holes 39a and 48a of 39 and 48, they are not limited to the leaf springs, but may be coil springs or elastic resin, and the mounting position is limited to the bearing mounting holes. However, any position may be used as long as the bearing can be biased in the direction to correct the off-track.

As described above, according to the present invention, the bearing mounting hole into which the bearing is loosely fitted is provided, and both ends of at least one of the spindle shaft and the actuator shaft are rotated to the housing via the bearing. An inner wall of the bearing mounting hole, which includes a bush that supports the bearing and a biasing unit that biases the bearing in a direction parallel to a straight line connecting the spindle shaft and the actuator shaft, and in which the bearing biased by the biasing unit presses the bearing. By providing two circumferentially spaced projections, when the temperature rises or falls, the spacing between the two circumferentially spaced projections increases or decreases, and this spacing increases or decreases. The spindle shaft or actuator shaft further enters or leaves between the protrusions, and Since the distance between the pivot and the actuator shaft increases or decreases more than the expansion and contraction of the housing itself, it is possible to realize a magnetic disk drive capable of suppressing the amount of off-latts to be small in a wide temperature range.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is a diagram for explaining attachment of bushes and bearings in FIG. 2, and FIG. 4 is FIG. 5 is a diagram showing the relationship between the device temperature and the off-track amount in FIG. 5, FIG. 5 is a configuration diagram of a conventional magnetic disk device, and FIG. 6 is a diagram showing the relationship between the device temperature and the off-track amount in FIG. 1 to 3, 21,33 are spindles, 22,44 are shafts, 23,24,36,39,45,46 are bearings, 25,26,38,39,47,48 are bushes, 25a, 26a, 39a, 48a are bearing mounting holes, 25b, 25c, 26b, 26c, 39b, 39c, 48b, 48c are protrusions, and 27, 28, 50, 51, 52, 53 are biasing means (springs).

Claims (1)

[Claims] 1. A spindle shaft to which a magnetic disk is attached, an actuator shaft for moving a head for writing / reading data to / from the magnetic disk to a target track, and a spindle shaft and the actuator shaft. A housing, a bearing arranged at both ends of at least one member of the spindle shaft or the actuator shaft, and a bearing mounting hole into which the bearing is loosely fitted,
A bush that rotatably supports both ends of at least one member of the spindle shaft or the actuator shaft to the housing via the bearing, and a bush parallel to a straight line connecting the spindle shaft and the actuator shaft. Urging means for urging the bearing, wherein the inner wall of the bearing mounting hole against which the bearing urged by the urging means presses is provided with two protrusions spaced apart in the circumferential direction. Characteristic magnetic disk device.