JPH10162548A - Magnetic disk drive - Google Patents

Abstract

(57) Abstract: An in-hub motor type spindle is used to reduce a positioning error due to flutter caused by rotation of a disk by generating a forced air flow from the inner circumference to the outer circumference between the disks. The air circulation path in the magnetic disk drive. A spindle for an in-hub motor is provided.
A flow path for flowing air is formed between the hub, the disk, and the disk spacer, and a flow from the inner circumference to the outer circumference is constantly generated between the disks. The flow toward the inner circumference generated between the uppermost disk and the cover by the rotation of the disk is taken into the gap between the disk and the spacer from the notch on the upper part of the spindle. A notch is formed in the inner diameter of the disk and spacer, and this is the air flow path in the spindle axial direction. This air is released between the disks from the opening formed in the notch in the inner diameter of the spacer, and a forced flow from the inner circumference to the outer circumference is formed between the disks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary recording apparatus for reading and writing information on a disk rotated by a magnetic head or an optical head or the like.
It is related to the method of realizing high-precision positioning.

[0002]

2. Description of the Related Art When a magnetic disk drive is constructed, when the air temperature between the magnetic disks becomes non-uniform, a phenomenon called flutter occurs in which the expansion rates of the magnetic disks differ due to thermal expansion. Due to the occurrence of the flutter, the positioning accuracy with respect to the track on each magnetic disk surface decreases.

In the conventional magnetic disk drive, the disk diameter was large, and in some models, a center blowing method was used as a measure against flutter. The center blowout method has an opening on the side of the disk spacer and generates a forced flow from the spindle side to the disk outer periphery to reduce turbulence generated between the disks, thereby reducing disk flutter. It is a method to make it. Conventionally, in this center blowing method, the blowing air was supplied to the inside of the spindle shaft from the opening above the spindle shaft. The conventional spindle is of a cantilever support type, and unlike the current in-hub type, the motor is provided outside the spindle hub, so that the spindle shaft can be hollowed. It was possible to carry out center blowing by introducing air and air.

[0004]

The current magnetic disk drive has a smaller disk diameter due to miniaturization.
In order to increase the processing speed, the number of rotations of the disk has increased and the disk flutter has increased. However, the track pitch becomes smaller due to the higher density, and the positioning error due to flutter must be reduced. As a countermeasure, a center blowing method that reduces flutter by blowing air from the disk spacer between the disks has been considered. However, in the current magnetic disk drive, the spindle changed to an in-hub motor type for high-density mounting, and air could not be taken into the spindle. In order to perform center blowing to reduce flutter, it is necessary to consider a new method of introducing air into the spindle.

[0005]

The inlet for taking in air for blowing out the center is realized by providing a notch in the upper or lower part of the spindle hub. In addition, the flow path for passing air taken in along the spindle axis is
This is achieved by providing notches on the disk spacer and the inner periphery of the disk. It is necessary to reduce the flow path resistance in order to blow out a lot of air. This is achieved by setting the area of the spacer opening larger than the total area of the inlet. Disk flutter is reduced by creating a forced flow from the inner circumference to the outer circumference. The flow from the inner circumference to the outer circumference of the disk is supplied to the gap between the spindle hub, the disk and the disk spacer from a notch provided at the upper or lower part of the spindle hub. However, since the clearance between the spindle hub and the disk or disk spacer is usually small, the flow path resistance is large, and it is difficult to secure a sufficient flow rate. Therefore, a notch is provided in the inner diameter of the disk and spacer to provide a flow path for air in the spindle axial direction. This can supply sufficient air for center blowing. The total area of the notch in the disk and the inner diameter of the spacer is larger than the total area of the inlet of the spindle hub, and the total area of the opening of the spacer is larger than the total area of this notch. As a result, the flow resistance decreases, the amount of air supplied between the disks increases, and the flutter reduction effect increases.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As the rotation speed of a disk has been increased, the flutter of the disk has become a problem to be solved in terms of positioning accuracy. When the disk diameter was as large as 14 ", flutter countermeasures were already considered. At present, the disk diameter is small, but due to the increase in the number of revolutions and the reduction in the thickness of the disk, the large diameter of the 3.5" disk The flutter is about the same as the disk. However, since the track pitch is reduced to a fraction, reducing the positioning error due to flutter has become an important issue. An example of the center blowing method implemented as a measure against flutter is described below. The center blowing method is a method to reduce the vortex between disks by blowing air in the radial direction from the inner circumference to the outer circumference of the disk to reduce disk flutter. Figure 11 shows an example of a spacer for center blowing. An opening 24 penetrating from the inner diameter side to the outer diameter side is provided on the side surface of the ring-shaped spacer 22. The center blowing method studied conventionally cannot be implemented with current magnetic disk drives.
This is because the structure of the spindle is different. Conventionally figure
As shown in FIG. 12, the motor 15 was provided outside the spindle hub 11 with the out-hub motor structure, so that the air supplied for center blowing could be taken in from the opening 16 of the spindle hub 11. The air taken in is blown out between the disks from the opening 24 of the disk spacer 22, and
From the outer periphery of the disk, the disk returns to the spindle hub again through the gap between the cover 31 or the base 32 and the disk and circulates. Therefore, in the case of an out-hub motor type spindle, the center blowing could be realized by incorporating a center blowing spacer. However, the current magnetic disk adopts an in-hub motor type structure in which a motor is formed in a spindle hub to reduce the size of the device. Therefore, in order to perform center blowing, it is necessary to consider a method of introducing air into the spindle and a method of providing an air flow path inside the spindle. The present invention relates to a method for solving these problems in order to perform center blowing in an in-hub motor type spindle. In the present invention, the supply of air blown out from the disk spacer to the space between the disks is as shown in FIG.
As shown in the embodiment, the process is performed by using the gap 25 between the in-hub motor type spindle hub 11, the disk 21, and the disk spacer 22. For this purpose, a notch 12 is provided in the upper part of the spindle hub 11, and air is taken into the gap 25 from here. Notch
12 is realized by providing a taper on the outer periphery of the spindle hub as shown in Fig. 2, for example. This taper may be provided on a part of the outer periphery of the spindle hub in consideration of workability and the like. The size of the notch should be large as long as the fastening force of the disc clamper 23 is not reduced. Also, as shown in FIG. 3, if a taper 29 is provided at the inner diameter of the disc clamper 23, the air intake efficiency is improved. Next, the flow path through which the entrapped air flows in the spindle axis direction is described. Figure
In FIG. 1, the gap 25 between the disk 21 and the disk spacer 22 and the spindle hub 11 is small to be a flow path for the intake air. In order to increase this gap, it is necessary to reduce the spindle diameter or increase the inner diameter of the disk and the disk spacer, but the former is an obstacle to incorporating the motor into the spindle, and the latter reduces the disk clamping force. There is a problem. Therefore, a notch is provided in a part of the inner diameter portion of the disk 11 and the disk spacer 22 to provide an air flow path. FIG. 4 shows an embodiment in which a concave portion 26 is provided in the inner diameter portion of the disk spacer 22 to serve as an air flow path. An opening 24 for the center outlet is provided in this recess to improve the outlet efficiency. This notch is also required for the disc. FIG. 5 shows an embodiment in which a concave portion 27 is provided in the inner diameter portion of the disc to provide an air flow path. The air inlet 12 of the spindle hub in FIG. 2, the notch 26 in FIG. 4, and the notch 27 in FIG.
Should be in the same position during assembly. Figure 6 shows the measurement results for the relationship between the blowout area and the amount of flutter reduction in the center blowout method. 3.5 "disc (0.8mm thick)
When rotating at 7200 rpm, about five disk flutter peaks are usually observed below 1 KHz, and the amplitude of the outermost circumference of the disk in the bending first-order mode at the lowest frequency of about 500 Hz was taken as a representative value. This shows that the flutter decreases as the opening area of the spacer is increased. If the total area of the spacer opening is the same as the total area of the air intake of the spindle hub, flutter will be approximately 60%.
%, And doubling the area of the spacer opening reduced flutter to about 40%. This indicates that it is better to make the total area of the opening of the spacer larger than the total area of the air intake to reduce the flow path resistance. However, if the area of the spacer opening is made twice or more the intake, the amount of flutter reduction can be expected to slow down. From the above, the total area of the spacer opening should be at least larger than the total area of the air intake, and it is considered optimal to make it 2 to 3 times. In Fig. 6, when the gap between the spindle and the spacer was reduced from 1.15mm to 0.15mm, the flutter amount increased. It is clear that the larger the gap between the spindle and the spacer, the better. In this actual measurement
The total clearance area at 1.15 mm is almost the same as the total air intake area of the spindle. It is considered that the total gap area should be set to be equal to or greater than the total area of the air intake. FIG. 7 shows another embodiment of the center blowing spacer of FIG. In this embodiment, the opening formed as a round hole in FIG. FIG. 8 shows an embodiment in which the air intake port 12 at the upper part of the spindle hub in FIG. Similarly, disc clamper 2 in FIG.
The taper 29 of 3 may be a step. FIG. 9 shows an embodiment in which a groove 13 is formed on the side of the spindle hub as an air flow path in the spindle shaft. FIG. 10 shows the air flow in the case of FIG. FIG. 9 enhances the blowing effect when implemented simultaneously with the embodiments of FIGS.

[0007]

According to the present invention, a vortex generated between the disks is reduced by creating a forced air flow from the inner circumference to the outer circumference between the disks, thereby reducing the disk flutter.
As a result, even when the disk is rotated at high speed, the positioning error due to flutter is reduced, and highly accurate positioning can be realized.

[Brief description of the drawings]

FIG. 1 is a circulation path of air blown out from a center in an in-hub motor type spindle.

FIG. 2 is an embodiment in which a taper is provided on an upper portion of a spindle to take in air for center blowing.

FIG. 3 shows an embodiment of a disc clamper for a spindle of an in-hub motor.

FIG. 4 is an embodiment of a center blowing spacer for a spindle of an in-hub motor.

FIG. 5 is an embodiment in which a concave portion is provided on the inner circumference of the disk as an air flow path in the spindle axial direction.

FIG. 6 shows the relationship between the opening area and the amount of flutter reduction at the center outlet of the in-hub motor spindle.

FIG. 7 shows another embodiment of the center blowing spacer.

FIG. 8 shows another embodiment of the air inlet above the spindle for center blowing.

FIG. 9 shows an embodiment in which a groove is provided on a side surface of the spindle shaft for an air flow path in the spindle axial direction.

FIG. 10 shows an air flow inside the apparatus in the embodiment of FIG.

FIG. 11 shows an example of a spacer used for center blowing with a spindle of an out-hub motor.

FIG. 12 shows an example of an air flow path of center blowing performed by a spindle of an out-hub motor.

[Explanation of symbols]

11: Spindle 12: Notch for air intake at the upper part of spindle 13: Slot for axial air flow path provided on spindle 2
1: Disc 22: Disc spacer 23: Disc clamp spacer 24, 25: Opening on the side of the spacer for center blowing 26: Notch for air flow in the spindle axial direction provided at the inner diameter of the spacer 27: At the inner diameter of the disc Notch for air flow path in the spindle axial direction provided 29: Notch for air intake provided in inner diameter portion of disc clamp spacer 31: Case cover 32: Case base 41, 42: Device for center blowing Internal air flow path

Claims (4)

[Claims] In a magnetic disk drive using an in-hub motor type spindle provided with a motor inside a spindle hub, air is taken into a gap between an outer diameter of a spindle housing and inner diameters of disks and disk spacers laminated thereon. A magnetic disk drive characterized in that an inlet of the disk is provided in a spindle housing, and an opening for blowing air taken in between the disks is provided in a disk spacer. 2. A magnetic disk drive according to claim 1, wherein an inflow port is provided in the upper surface of the spindle hub or the inner diameter of the disk clamper by a notch or the like for taking in air. 3. The magnetic disk drive according to claim 1, wherein a notch or the like for flowing air in a spindle axial direction is provided in an inner diameter portion of the disk and the disk spacer. 4. The magnetic disk drive according to claim 1, wherein the total area of the air inlet provided in the spindle housing is a1, a2.
A magnetic disk drive characterized by satisfying a relationship of approximately a1 ≦ a2 ≦ a3, where a2 is the total area of the notch provided in the inner diameter portion of the disk and the spacer and a3 is the total area of the opening provided in the spacer. .