JPH0234111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic disk storage device suitable for realizing miniaturization, high density, and large capacity.

[Background of the invention]

In recent years, 8 has been used as a storage device for small-scale electronic computers.
Small magnetic disk storage devices using inch, 5 inch, and 3 inch diameter magnetic disks are becoming popular. It would be very convenient if such a small magnetic disk storage device was made compatible with a flexible disk device. Here, compatibility means, for example, replacing an FDD (flexible disk device) installed in a TEC device (terminal controller) with the above-mentioned small disk storage device. For compatibility, it is necessary to make the physical and electrical interfaces equivalent to those of flexible disk devices. For this reason, there is a strong desire to develop a miniaturized high-density, large-capacity magnetic disk storage device, but it is technically more difficult than large-sized magnetic disk storage devices.

Conventional small magnetic disk storage devices of about 5 inches have low recording density and do not use a servo positioning method, so they have large track spacing margins and the spindle is slightly tilted, resulting in off-track phenomenon (due to thermal displacement, etc.). Even if there is a deviation from the track address position of the target track address, making it impossible to read the desired track address information, it is possible to read up to about 10 μm without any problem.Also, even if the spindle housing rigidity is a little small, there is no servo head, so servo vibration can be avoided. Does not occur. Therefore, the spindle housing is made of aluminum die-casting and is made of a different material from the pair of bearings that support the spindle shaft, so the spindle housing and the bearings have a different coefficient of linear expansion. , and gaps are created due to temperature changes.
As a result, the spindle shaft will tilt.

On the other hand, in order to achieve high density at low cost, the track spacing and track width must be made very small. As a result, the track spacing margin becomes a small value of about 1.5 μm. Therefore, the off-track phenomenon caused by temperature changes, which would not be a problem when the recording density is low and the track spacing margin is relatively large, becomes a problem.

The parts housed in the sealed head disk assembly (hereinafter referred to as HDA) of a magnetic disk storage device using hard magnetic disks must be clean. Additionally, foreign particles must not be generated inside the HDA or foreign particles must be allowed to enter from the outside. This is because the magnetic disk surface and magnetic head float due to the air bearing effect while maintaining a flying height of about 0.5 μm, and the magnetic disk surface and magnetic head are rotating at high speed in close proximity. If foreign particles are present in between, they will damage the magnetic disk surface, making it impossible to record/reproduce information. For this reason, the parts to be stored in the HDA are generally subjected to ultrasonic cleaning, etc., and all parts are assembled in a dust-proof room in a very clean atmosphere. However, no matter how careful one is, the presence of some foreign particles cannot be avoided. These foreign particles must be removed by all means since they significantly impair the reliability of the device.

Conventional dust filtration mechanisms are mainly based on self-circulating air systems. The self-circulating air system circulates the air inside the HDA (pumping effect) by using the difference between the inner and outer circumferences of a magnetic disk that rotates at high speed.

One type of dust filtration mechanism for a self-circulating air system is one in which a flat dust filtration mechanism is provided above the magnetic disk assembly to purify the air inside the HDA enclosure. In this method, since the dust filtration mechanism has a flat plate structure, the filtration efficiency is poor and it is difficult to quickly clean the inside. Further, unless a certain distance is maintained between the upper disk surface and the flat dust filtering mechanism, the high-speed rotation of the magnetic disk increases windage loss and increases the amount of heat generated, which limits miniaturization. Furthermore, if this interval is large, dust will not pass through the dust filtering mechanism, resulting in a disadvantage that the filtering efficiency will be reduced.

Another example of a self-circulating air system dust filtration mechanism is a cubic dust filtration mechanism within the HDA enclosure. In this method, in order to increase the surface area of the filter medium and increase the filtration efficiency, the filter medium is folded into several layers, which increases the size of the dust filtration mechanism, making it unsuitable for miniaturization. Furthermore, if the number of folded layers of the filter medium is reduced and the shape is made smaller so that such a dust filtration mechanism can be housed in the sealed body of a 5-inch or 3-inch diameter magnetic disk storage device, dust As a result of the increased resistance when a moderate amount of air passes through the filtration mechanism,
Pressure loss increases and internal circulation efficiency and dust collection efficiency deteriorate. Furthermore, in order to completely seal the end surface (the surface in contact with the casing) of the casing forming the cubic dust filtration mechanism and the folded structure of the filter medium, the surrounding area must be sealed with an adhesive or the like. Furthermore, when adhering, the work is difficult because the end faces are not flat, and the number of work steps increases. This makes the dust filtering mechanism extremely expensive, making it unsuitable for small-sized magnetic disk storage devices that should be manufactured at low cost.

Next, the drawbacks of the air circulation system of the conventional small magnetic disk storage device will be explained.

It is necessary to circulate the air inside the HDA in order to remove foreign particles within the HDA enclosure and to maintain a constant temperature within the enclosure. In order to be compatible and replaceable with flexible disk devices, there is a limit to the height of the device itself, and the air circulation method is to circulate through the base at the bottom of the device. In this method, air flows in from the bottom of the hub attached to the spindle shaft, multiple through holes are provided on the side of the hub, and multiple through holes are provided in multiple disk spacers to circulate the internal air. The subject is what makes it happen.

However, with this method, there is a very negative pressure between the outer diameter of the spindle housing and the hub, so oil droplets from the base oil of the bearing grease due to the high speed rotation of the spindle bearing and leakage from the outside into the HDA sealing body can occur. This will encourage the inflow of foreign particles. Therefore, in order to eliminate this drawback, a magnetic fluid seal is formed by injecting a magnetic fluid between the spindle shaft and the spindle housing, which are to be sealed during rotation, and forming a magnetic circuit.

However, magnetic fluid seals have many parts,
It also increases the number of man-hours required, making it very expensive. In addition, it is very difficult to inject the magnetic fluid, and if the appropriate amount is not injected, the magnetic fluid will leak and scatter during rotation. Furthermore, the sealing effect decreases with long-term use. Furthermore, since the magnetic fluid is in contact with the spindle shaft, variations in viscous torque occur, resulting in variations in rise/fall times and uneven rotation when temperature changes.

Moreover, the plurality of through holes provided in the side surface of the hub described above reduce the rigidity of the hub and cause vibration.

Next, the head positioning mechanism will be explained.

Flexible disk devices can be installed in various orientations such as horizontal, vertical, and vertical, so in order to replace flexible disk devices with small magnetic disk storage devices, the head positioning mechanism can also be installed in various orientations. It is necessary to configure it so that

Head positioning mechanisms can be roughly divided into two types: a rotational drive system that moves the magnetic head rotationally, and a linear drive system that moves the magnetic head linearly.

When mounted vertically, the weight of the carriage will be different in the forward and backward directions in the linear drive system, so when using a voice coil, two types of speed curves are required for speed control, and two types of speed curves are required for speed control.
Since it requires various types of control mechanisms, it is expensive.

Furthermore, the same can be said of the rotational drive system since the first moment relative to the rotational support shaft is not balanced. Further, when the device is transported, the head and the magnetic disk come into rotational contact due to the unbalance of the first moment, causing damage to the magnetic disk. Furthermore, the lack of rigidity of the rotating support shaft induces vibrations in the servo head, and the ease of assembly is extremely poor.

[Purpose of the invention]

The purpose of the present invention is to improve the off-track margin, make the dust filtration mechanism more compact, inexpensive, and high-performance, and reduce servo head vibration, in order to eliminate the drawbacks of the prior art as described above. The head positioning mechanism is configured so that
Inexpensive, compatible with flexible disk devices
The objective is to realize a compact, large-capacity, high-performance magnetic disk storage device.

[Summary of the invention]

To achieve the above object, the magnetic disk storage device of the present invention includes a rotatable spindle shaft, a spindle housing that supports the spindle shaft via a bearing, and a spindle housing that supports the magnetic disk and rotates in conjunction with the spindle shaft. In the magnetic disk storage device, the spindle housing is joined to the bearing, and has a head positioning mechanism for positioning the magnetic head on the magnetic disk in a sealed body formed by a base member and a cover. a first member having the same coefficient of linear expansion as the bearing; and a first member joined to the base member, having the same coefficient of linear expansion as the base member, and connected to the first member at the center of the first member. a second member joined nearby;
The member is characterized in that it is configured apart from the bearing so as not to cover the outer periphery of the bearing.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The magnetic disk assembly 1 generally includes a spindle portion 4 that rotatably supports a spindle shaft 5, and a hub 12 that supports a magnetic disk 11. The spindle housing 9 of the spindle part 4 has a first member 100 and a second member 1 made of different materials.
01 are joined near the center of the first member 100, are individually fixed to the base 10, and rotatably support the spindle shaft 5 via bearings 6 and 7. The first member is cylindrical and the second member is cylindrical with a collar at the bottom. The hub 12 is fixed to the upper part of the spindle shaft 5 of the spindle section 4 by shrink fitting or the like, and rotates in conjunction with the spindle shaft 5 connected to the drive motor 3 of the rotation drive section 2 . The spindle shaft 5 is made as thick as possible to increase rigidity in order to improve rotation accuracy. In addition, in order to obtain high-speed and high-precision rotation,
The spindle shaft 5 is supported by a pair of upper and lower bearings 6, 7, and by using ultra-high precision bearings 6, 7, accurate positioning in the radial and axial directions is achieved.
A spring 8 is provided between the bearings 6 and 7 to provide an appropriate preload, thereby increasing the rigidity of the bearings 6 and 7 and suppressing vibration of the spindle shaft 5.

The first member 100 of the spindle housing 9 is
An iron-based material (for example, rigid stainless steel, etc.) with a linear expansion coefficient equivalent to that of the outer ring material of the bearings 6 and 7 is used. Therefore, even if there is a temperature change, the first
Since the amount of deformation of the member 100 and the bearings 6 and 7 is the same, no gap is generated between them, and it is possible to prevent the spindle shaft 5 from tilting due to temperature changes. Further, the first member 100 is made of iron and has a cylindrical shape to increase the rigidity of the housing. Therefore, the natural frequency of the spindle portion 4 can be increased, and the influence on servo vibration can be reduced.

The second member 101 of the spindle housing 9 is
Since it is a member for fixing and fastening the spindle part 4 to the base 10, the base 1 due to the difference in linear expansion coefficient
The same aluminum material as the base 10 (for example, aluminum die-casting, etc.) is used to prevent thermal deformation (bimetal effect). By eliminating the dissimilar combination of metals in this way, the base 10 will not be thermally deformed due to the bimetallic effect, and the relative position between the head positioning mechanism installed on the base 10 and the magnetic disk 11 will not fluctuate.
Off-track phenomenon can be prevented. At the same time, the off-track phenomenon caused by the inclination of the spindle shaft 5 can also be prevented.

By configuring the spindle housing 9 as described above, it has become possible to increase the off-track margin to 1.5 μm.

The hub 12 that supports the magnetic disk 11 is a rotating system fixed to the upper part of the spindle shaft 5, and high-speed bearings 6 and 7 are installed in the gap between this rotating system and the fixed system spindle housing 9. Efforts have been made to prevent the scattering of the Bärkung grease base oil that is generated by rotation. In other words, we selected the grease material and used wild range grease with less oil droplets from the base oil, and also installed a non-contact labyrinth mechanism (spindle housing 9).
A sealing mechanism having a small uneven gap between the inner and outer diameter parts of the upper part of the first member 100 and the hub 12. This gap is called a labyrinth gap 14, and since oil droplets accumulate in the recess 15, this recess 15 is called an oil droplet pool. ), the structure is such that oil droplets do not diffuse into the HDA sealing body 13. This labyrinth mechanism makes the labyrinth gap 14 as small as possible and improves the sealing effect by increasing the machining accuracy of the inner and outer diameters of the upper part of the first member 100 and the corresponding hub 12. Further, in order to increase the labyrinth resistance as much as possible, the forming part of the labyrinth gap 14 is made as long as possible, and a plurality of oil droplets 15 are provided to maximize the sealing effect. By doing this, we were able to improve the labyrinth resistance by about 1.5 times compared to the conventional method.

As an air circulation system, in this embodiment, the hub 12
By providing a plurality of holes 22 in the disk clamp 21 for positioning and fixing the magnetic disk 11 and disk spacer 16, air can be introduced from the top of the device onto the surface of the magnetic disk 11 without introducing air from the bottom of the device. The method is adopted.

In order to guide air from the hole 22 onto the surface of the magnetic disk 11, the structure is as follows. That is,
The outer circumferential side surface 20 of the hub 12 is an inclined surface, and a tapered air flow path is formed between the plurality of magnetic disks 11 and the guide portion 19 for positioning and guiding the plurality of disk spacers 16. The air flow passage has a tapered shape, and the flow passage is wide at the upper part where the suction air volume is large and the flow passage is narrow at the lower part where the suction volume is small, so that an appropriate air volume is guided to each magnetic disk 11. Further, the guide portion 19 is formed in a convex shape and serves as an impeller. Therefore, the convex guide portion 19 also provides an appropriate amount of circulating air. In addition,
The hub 12 has a wall thickness that does not reduce rigidity, and has a rib shape to further increase rigidity.

A plurality of through holes 17 are provided in each disk spacer 16 to guide air to each magnetic disk 11 from the tapered airflow passage. The air flows through the hole 22 of the disk clamp 21 → the tapered air flow path → the through hole 17 of the disk spacer → the magnetic disk 11
The air circulates as follows: → conical dust filter mechanism 41 → hole 22, and there is no need to provide a through hole for air circulation in the hub 12, so the rigidity of the hub 12 is not reduced.

In addition, the outer diameter of the spindle housing 9 and the hub 1
Since there is no air circulation between the spindle portion 4 (bearing side) and the spindle portion 4 (bearing side), there is no negative pressure. Therefore, the flow of oil droplets of the base oil of the bearings 6 and 7 or foreign particles from the outside into the HDA sealing body is suppressed, and this flow is completely prevented by the labyrinth mechanism.

Next, the head positioning mechanism 24 is shown in FIG.
This will be explained using FIG.

The carriage 25 has a plurality of magnetic heads 2 at one end.
3 is connected to the access arm 26, the other end of which is engaged with the voice coil section 27, and the rotational fulcrum of the pivot shaft 28 is disposed at the center of gravity of these arms. There is a problem with this location of the center of gravity. That is, in the rotary positioning mechanism, since the magnetic head 23 moves without performing circular motion on the surface of the magnetic disk 11, the magnetic head 23 always makes a small angle (hereinafter referred to as yaw) with respect to the tangential direction of the track on the magnetic disk 11. It has the disadvantage of being tilted by an angle (called an angle). The occurrence of this yaw angle causes instability in the flying height of the magnetic head 23, induces a head crash phenomenon between the magnetic head 23 and the magnetic disk 11, and substantially reduces the readout track on the inner and outer peripheries of the magnetic disk 11. Since the widths are different, a phenomenon occurs that induces instability of the recording/reproduction signal. Experiments have shown that the limit for these phenomena is a yaw angle of 13 degrees. Therefore, in this embodiment, the yaw angle when the magnetic head is floating on the inner circumferential side is set to 7 degrees, and the yaw angle on the outer circumferential side where the circumferential speed is fast, the flying height is high, and the recording and reproducing characteristics are relatively good. I made it larger. In order to set the yaw angle as described above, it was decided that the distance from the pivot shaft 28, which is a rotation support part, to the position of the magnetic head 23 should be as long as about 70 mm. Since the magnetic head 23 side is made longer in this way, the magnetic head 23
The mass on the side increases, and if this continues, the first moment cannot be balanced with the voice coil section 27 side. Therefore, the voice coil bobbin 29 that constitutes the voice coil section 27 is made of a material with a large mass (for example, zinc alloy, etc.), and the material of the voice coil 30 is made of a material with a large mass (for example, a copper wire, etc.). This makes it possible to balance the first moment with respect to the rotational support shaft. Therefore, it can be operated in any mounting direction, and there is no need for a carriage lock to prevent problems that may occur during transportation.

A pivot shaft 28, which is a rotation support shaft of the carriage 25, is fixed on a carriage block 31. The carriage block 31 is for fixing the head positioning mechanism 24 onto the base 10, and is made of the same material as the base 10 in order to prevent thermal deformation of the base 10 due to dissimilar metal bonding. A pair of highly rigid bearings 32 (for example, needle bearings) are press-fitted into the carriage 25 at predetermined positions. This bearing 32 rotates on the pivot shaft 28, but in order to eliminate the gap between the pivot shaft 28 and the bearing 32 and increase rigidity, a semi-circle piece 3 is placed at the position of the pivot shaft 28 corresponding to each bearing 32.
3, a preload spring 34 is provided, and a preload is applied. In addition, in order to maintain accuracy in the vertical direction, a thrust bearing plate 35 is press-fitted into the carriage 25, a thrust bearing group 36 is provided on the pivot shaft 28 and the upper part of the thrust bearing plate 35, and a preload is applied by a preload spring 37. Positioned. This configuration requires carriage block 3.
1 can be assembled from above, so work efficiency is greatly improved.

The magnetic circuit section 38, which is the drive source for the voice coil 30, is composed of two permanent magnets, one center yoke, and two side yokes.
When current is supplied to the voice coil 30, the carriage 25 is rotated in the radial direction of the magnetic disk 11 due to the electromagnetic force generated between the voice coil 30 and the permanent magnet. Such a head positioning mechanism 24 is fixed to the base 10.

The base 10 has a rib structure to reduce weight and increase rigidity. Since the rib structure can increase the surface area, it is also useful for increasing the heat dissipation effect within the sealing body 13. In order to increase the rigidity of the base 10, the end face of the base 10 is further raised as shown in the figure. A groove is provided on the upper surface of this base rising part, and a gasket 39 is provided in the groove to form a sealing body.
is installed. The reason why the packing 39 is placed in the groove is to set the amount of deflection of the packing 39 to an amount that will not cause permanent deformation (approximately 20 to 30% of the packing thickness). Furthermore, a cover 18 is fixed via a packing 39 to form the sealing body 13. The cover 18 is also made of the same material as the base 10 in order to avoid metal dissimilar bonding with the base 10. Cover 1 corresponding to the upper part of spindle part 4
A breathing filter 40 is provided at position 8 to take in outside air, but this breathing filter 40 prevents external dust from flowing in from the spindle portion 4 due to changes in the volume of air within the sealing body 13 due to temperature changes. In order to achieve this, it is designed to have a pressure loss smaller than the inflow pressure loss (resistance) of the spindle section 4.

Further, a conical dust filtering mechanism 41 is fixed to the cover 18 in order to remove foreign particles within the sealing body 13. This conical dust filtration mechanism 41 has its center located at the center of the spindle portion 4 and forms an air circulation path together with the air circulation system.
Magnetic disk 1 at the top of magnetic disk assembly 1
It is stored in a very narrow space between 1 and cover 18. Further, the conical dust filtration mechanism 41 improves filtration efficiency by allowing air containing foreign particles to completely pass through the filter 42 without flowing back. That is, the outer circumferential side of the magnetic disk 11 is placed very close to the magnetic disk 11 to prevent backflow, and the inner circumferential side is joined to the cover 18 to limit the direction of air movement to the direction in which the air passes through the filter 42, thereby preventing foreign matter. All of the air containing particles is allowed to pass through the filter 42. For this reason, the shape of the conical dust filtering mechanism 41 is made conical.

The conical dust filtering mechanism 41 includes a conical member 44 having a plurality of air inflow holes 43 and a filter 42, and the filter 42 is fixed to the conical member 44 by adhesive. Since this is bonded in a flat shape, the bonding work is easy, and the shape is simple, so a very inexpensive filtration mechanism can be obtained. The conical member 44 has a head access hole 45 to ensure a passage for the magnetic head 23 when the magnetic head 23 accesses the magnetic disk 11. Further, in order to prevent foreign particles from flowing back into the head access hole 45, a downwardly downward portion 46 close to the surface of the magnetic disk 11 is formed around the head access hole 45. The air circulation flow for removing foreign particles within the sealing body 13 flows in the direction of the arrow in FIG. 2, and filtration is complete.

〔Effect of the invention〕

As explained above, according to the present invention, since the first member 100 and the second member 101 are connected near the center of the first member, the influence of the bimetal can be ignored, and the outer circumference of the bearing Since the second member 101 does not cover the parts (bearings 6, 7), there is an effect that bimetal formation does not occur at the outer peripheral part of the bearing. Furthermore, the material of the first member 100 that is joined to the spindle shaft bearing is the same as that of the spindle shaft bearing, and the material of the second member 101 that is joined to the base is the same as that of the base, thereby improving the off-track margin. can be done. Further, since the hub and base are rib-shaped and a raised portion is provided on the outer peripheral edge of the base, the dust filtering mechanism can be made compact, inexpensive, and high-performance. In addition, vibrations of the servo head can be reduced by increasing the rigidity of the entire mounting by forming the hub shape into a rib shape without through holes. Furthermore, by making the first moment of the rotary head positioning mechanism the same with respect to the rotational axis, the device can be mounted in any direction, and is inexpensive, compact, large capacity, and compatible with flexible disk devices. A high-performance magnetic disk storage device can be realized.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
The figure is a side sectional view of FIG. 1. 5: Spindle shaft, 6, 7: Bearing, 9:
Spindle housing, 10: Base, 12: Hub, 14: Labyrinth gap, 15: Oil pool,
28: Pivot shaft, 41: Conical dust filtration mechanism, 46: Standing portion.

Claims (1)

[Scope of Claims] 1. A rotatable spindle shaft, a spindle housing that supports the spindle shaft via a bearing, a hub that supports a magnetic disk and rotates in conjunction with the spindle shaft, and a magnetic head that supports the magnetic disk. In a magnetic disk storage device having a head positioning mechanism for positioning on the disk within a sealed body formed by a base member and a cover, the spindle housing is joined to the bearing and has the same coefficient of linear expansion as the bearing. a second member that is joined to the base member, has the same coefficient of linear expansion as the base member, and is connected to the first member near the center of the first member; What is claimed is: 1. A magnetic disk storage device comprising: and wherein the second member is spaced apart from the bearing so as not to cover the outer peripheral portion of the bearing. 2. The magnetic disk storage device according to claim 1, wherein the hub and the base are rib-shaped and include a raised portion on the outer peripheral edge of the base.