JPH02198058A - Fixed magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce eccentricity due to disk loading with simple structure by designing the shape of a hole loaded to a spindle motor hub of a center part so that an inner circumferential face of a disk is engaged and positioned at a prescribed number of positions with respect to nearly a cylindrical face of the spindle motor hub. CONSTITUTION:The inner circumferential face of a disk is formed nearly a triangle shape using a flexible part 8 as one side and engaged and fixed with a spindle motor hub 1 at three positions, while engaging one point of other two sides to a main shaft hub 1, and the relative position of the hub 1 and the disk is determined definitely and stably. The flexible part 8 of the disk protrudes to its center when it is not loaded to the bus 1, and when the disk is loaded to the hub 1, the disk is loaded while the projecting part is bent, then the flexible part 8 is engaged and is brought into contact with the hub 1 while giving a pre-load in the direction 7. The disk has an automatic center aligning function by the pre-load, the alignment is decided automatically and the eccentricity is avoided by deciding the inner circumference of the disk so that the center of gravity of the disk in the loading state is coincident with a rotating center 2 of the hub 1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention improves the mechanical reliability of a disk drive by reducing eccentricity that occurs when a disk is mounted, and also uses servo signals written on the disk for head positioning. The present invention relates to a fixed magnetic disk device in which a disk on which servo information has already been written can be easily and accurately mounted when using a fixed magnetic disk device, which is excellent in mass productivity, and which can perform sufficient position tracking control.

[Conventional technology]

FIG. 2 shows an explanatory diagram of the installation and eccentricity of the disk into the main shaft motor of a conventional fixed disk device.

A magnetic disk 20 having a circular hole with a rotation center 22 and a diameter B in a main shaft motor hub 21 with a rotation center 23 and a diameter A.
is fixed. To ensure smooth installation, be sure to press F (
There is a clearance called F-B-A), and the amount usually ranges from 10 microns to 80 microns. Therefore, the eccentricity C is the distance between the cylinder rotation center 22 and 23, which corresponds to half of the clearance F. In the case of a fixed magnetic disk, the spindle motor rotates at a high speed of about 3,000 to 4,000 rpm, but in conventional magnetic disk drives, the load in the radial direction of the spindle motor increases as it rotates at high speed with the eccentric load mentioned above. This had an adverse effect on the bearings of the main shaft motor, contributing to a reduction in bearing life. Particularly when the distance between the center of gravity between the bearing and the magnetic disk is long, the shaft swings around, damaging the bearing and significantly reducing the mechanical reliability of the magnetic disk drive.

In particular, for large machines of 5.25 inches or larger, this amount of eccentricity has been suppressed by balancing or improving the dimensional precision of the spindle motor.

In addition, high-speed eccentric rotation generates vibrations and noise, and the vibrations are transmitted through the housing, reducing the actuator's head positioning accuracy, and the noise causes extreme discomfort to the host system user.

In a fixed magnetic disk drive that rotates with eccentricity C, the magnetic head 24 draws a radial locus around the center 23 of the spindle motor hub to read and write data. If damage occurs to the bearing as described above, or if the bearing is deflected due to fluctuating centrifugal force, the shaft will start whirling, and if the amount of eccentricity is C, then the trajectory drawn by the head 24 on the disk 20 becomes a circle with a radius of E, resulting in a maximum deviation of F, resulting in a fatal defect in which data cannot be read.

Removable fixed magnetic disk devices such as diskbacks were even more seriously affected.

In other words, the clearance F between the diameter A of the spindle motor hub 21 and the inner diameter B of the disk 20 directly causes a deviation in the track position on the head and disk (referred to as off-track), resulting in data loss regardless of bearing damage. There were cases where it was not possible to read or write to the regular track position.

As described above, conventional fixed magnetic disk drives have significantly deteriorated data reliability, which is a basic characteristic of fixed magnetic disk drives.

In surface servo (one surface is used to generate position information for head positioning) magnetic disk drives, a servo track writer (S) is used to write signals on the servo surface.
, T, W), etc., were used to write servo information using a dedicated high-precision signal writing device.

At this time, the main spindle motor and magnetic disk were assembled in the case, and the whole case was placed inside an S, T, or W, and the main spindle motor of the magnetic disk device was rotated to write a servo signal using the head. This was to absorb off-track caused by eccentricity and whirling around the main motor shaft. However, with this conventional method, it is necessary to take the magnetic disk drive in and out of S, T, and W because writing is performed one by one, and it takes a very long time to write the servo signal and check the accuracy. However, mass production was not possible and the cost was high, which was a major drawback of this type of magnetic disk drive.

In addition, because magnetic disk drives are constantly moving in and out of the S, T, and W of the first row, dust gets into the STW, which causes the disk to get into the exposed magnetic disk, increasing disk damage (defects and head crashes),
This caused damage to the STW head. In particular, defects and head crashes significantly reduced the reliability of magnetic disks.

FIG. 3 is an explanatory diagram showing the relationship between a movable part such as a write head of a servo track writer (STW) of a conventional planar servo disk device and a magnetic disk device housing.

When a servo signal is written on the magnetic disk surface 37 by STW, a main shaft motor 35 is attached to the housing 36 of the magnetic disk device fixed to the housing 31 of the STW to drive the disk. The STW head 33 for writing signals and the clock head 34 for writing clock signals onto the disk surface 38 are S
It is fixed to the TW actuator 32 and moves while being positioned using, for example, a laser positioning device.

Therefore, in order to write signals on the disk surface 37, 38, the head 33, clock head 34, Gailles head (not shown), etc. are located on the disk, so the height of the casing 36 of the magnetic disk device is at least one plate. It can only be raised to a height H where the disc is exposed. Therefore, the side walls of the magnetic disk housing 36 have to be made low, which greatly reduces the rigidity of the housing and generates a mechanical resonance point, particularly below 3 KHz, which is harmful to servo control, making servo control impossible. In addition, the positioning accuracy may be degraded, seek errors may occur, and the data reliability of the magnetic disk device may be degraded. To prevent this, expensive vibration-proofing materials and reinforcing materials had to be used.

In addition, since the magnetic disk housing and the chamber that covers it are joined near the magnetic disk and head, radiation noise is likely to enter through this gap, which increases the frequency of data errors and reduces the reliability of the magnetic disk drive. This was a factor that led to a significant decline.

Furthermore, as mentioned above, the servo surface is usually located on the top surface of the stacked disks in order to prevent the STW movable section from interfering with the side surface of the housing. However, this was directly affected by off-track between each head due to thermal deformation of the spindle motor, head support, and housing, resulting in increased off-track at the bottom surface and reduced data reliability. In addition, to compensate for this, position information for correction is written on each other data surface,
The positioning of each data head was performed by duplicating the surface servo information. This method reduces the recording area on the data surface, requires an additional circuit to reproduce the corrected position information of each data head, and furthermore, it takes time to correct off-track in each data head, so it is difficult to read. The write speed (data throughput) was extremely low, which was a major defect that hindered high-speed data transfer, which is the most important characteristic of magnetic disk drives.

[Problem to be solved by the invention]

As described above, in the conventional technology, 1) eccentricity occurs due to play between the spindle motor hub and the inner circumference of the magnetic disk, which causes high speed rotation, shortening the life of the spindle motor and impairing mechanical reliability.

2) Noise and vibration are generated due to high-speed eccentric rotation, and the noise gives discomfort to the user of the host system, and the vibration reduces head positioning accuracy.

3) Due to 1), the bearings were deflected or damaged, causing non-repeatable off-track due to whirling, impairing the data reliability of the device.

4) Particularly in removable fixed magnetic disk drives, the backlash between the spindle motor hub and the inner periphery of the disk, as well as the non-repetitive off-track mentioned in 3), directly causes misalignment between the head and the track, extremely reducing data reliability. was.

5) In order to prevent 1) to 4), it was necessary to use large, high-precision, high-rigidity bearings, balance after the disk was installed, and use of high-precision hubs, leading to larger and more expensive equipment.

6) In a surface servo disk device, the inside of the STW is contaminated with dust due to frequent loading and unloading of the disk device, and this dust also enters the magnetic disk device and causes damage to the device head and disk.
M (a), damaging data reliability.

Also, the STW head was easily damaged.

7) It takes a very long time to take in and out one unit at a time with the disk and spindle motor installed, write servo information, and inspect it, which hinders mass production of the device and increases manufacturing costs. was.

8) Because the STW movable part enters the magnetic disk device,
The side height of the magnetic disk device housing cannot be obtained, reducing the rigidity of the housing, causing mechanical resonance of approximately 3 KHz or less that is harmful to servo position control and speed control, and decreasing positioning accuracy.
This promoted the occurrence of seek errors and significantly impaired the reliability of magnetic disk drives.

9) In order to prevent 8), expensive vibration isolating materials and reinforcing materials were used, resulting in larger and more expensive equipment.

10) Since the joint surface between the housing and chamber of a magnetic disk device is close to the disk and head, data errors occur due to radiated noise that enters from the gap and noise that is re-radiated from the housing joint surface, etc., reducing the data reliability of the device. was damaging.

11) Since the servo surface had to be located on the uppermost surface of the stacked disks, there was a large misalignment between the servo head and other data heads, which reduced data reliability due to off-track.

12) In order to compensate for 11), a method was used in which data surface servo was used in combination, but this required an additional circuit and also required time to compensate for the off-track of each data head. This method had problems such as significantly reducing the data transfer speed of the disk device.

The present invention is intended to solve these problems.The purpose of the present invention is to reduce the eccentricity caused by mounting the disk through a simple structure of the inner periphery of the disk, thereby achieving long life, low noise, and
Mechanical reliability due to high precision positioning and reduction of off-tracks.
The object of the present invention is to improve data reliability, make a surface servo disk device smaller and more rigid, and provide a fixed magnetic disk device that is inexpensive and highly reliable through mass production.

[Means to solve the problem]

The fixed magnetic disk device of the present invention has a hole in the center for mounting on the spindle motor hub, and has hole shapes that engage and position the substantially cylindrical surface of the spindle motor hub at three locations, and at least one surface. It is characterized by mounting at least one magnetic disk on which a servo signal for head positioning is written.

[For production]

An explanatory diagram of the principle used for positioning according to the present invention is shown in FIG.

In order to stably and uniquely position an object, the object must be supported at three points.

Uniquely determining the relative position between the approximately cylindrical surface of the spindle motor hub 41 and the disk 40 is such that the inner circumference of the disk 42 engages the outer circumference of the spindle motor hub 41 at three fulcrums (schematically indicated by triangle marks) of 43°44.45. This is achieved by mutual support.

Also, one of the fulcrums 43, 44, 45 is automatically positioned by preloading.

Furthermore, by aligning the center of gravity 46 of the main shaft motor knob 41 and the center of gravity 47 of the disk 40 in a plane while engaged at three points, eccentricity in the rotation system can be eliminated.

〔Example〕

FIG. 1 is an explanatory diagram showing an example of a main shaft motor hub (hereinafter referred to as hub) of a fixed magnetic disk device of the present invention and positioning of the inner circumference of the disk.

A disk 9 is engaged with and fixed to the inner circumference of a hub (main shaft motor knob λ) 1 having a substantially cylindrical surface as shown by the solid line in the figure. The disk 9 has a bridge-shaped flexible portion shown by diagonal lines on a part of its inner periphery to be attached to the hub 1, and contacts the hub 1 at approximately one location while applying pressure in the direction of the arrow 7. Also disk 9
The inner periphery has a substantially triangular shape with the flexible part 8 as one side, and one place on each of the other two sides engages with the hub 1, thereby forming a triangular shape.
The relative positions of the hub 1 and the disk 9 are uniquely and stably determined by engaging and fixing them at several points. The flexible part 8 of the disk 9 is connected to the hub 1
If it is not attached to the body, it has a protruding shape as shown by the broken line in the figure. When attached to the hub 1, by bending this portion, the flexible portion engages the hub 1 while generating a preload force. Due to this preloaded portion, the disk 9 exhibits a self-aligning function and its position is automatically determined. Therefore, positioning is completed simply by pushing the disk 9 into the hub 1, which saves man-hours. Furthermore, by determining the inner circumference of the disk 9 so that the center of gravity of the disk 9 coincides with the center of rotation (center of gravity) of the spindle motor hub 1 in the tubed state, eccentricity does not occur.

FIG. 5 is an explanatory diagram showing another example of the present invention.

The inner periphery 53 of the magnetic disk 50 has a substantially concave side, one of which
It has a bridge-like flexible portion 58 at the apex. Flexible part 5
8 has a protruding shape as shown by the broken line when not attached to the hub 51, and when attached, bends and generates a preload force.
It is engaged at one location on each of the two sides of the rectangle and is stably positioned. Further, by selecting the shape of the inner circumference so that the center of rotation of the hub 51 and the center of gravity of the disk 50 coincide with each other when the disk is attached, eccentric rotational loads are not generated.

FIG. 6 is an explanatory diagram showing another example of the present invention.

The inner periphery 63 of the magnetic disk 60 has a shape as shown in the figure, and the flexible member 68 is engaged with the inner periphery of the disk 60 in the shape shown by the broken line before the disk 60 is attached to the hub 62. When the disk 60 is attached to the hub 61, the flexible member 68 is bent and engages with the /X pro 1 at approximately one location to apply preload. At the same time, the hub 61 and disc 60 are
It engages at two locations (3) and is stably positioned at a total of three locations.

Moreover, the center of gravity of the flexible member 68 and the disc 60 is
The shape is determined so that it coincides with the rotation center 62 of.

Since eccentricity does not occur in this way, the load on the main shaft motor bearing is reduced and a long service life can be achieved.In addition, since there is no deflection of the bearing due to whirling, there is no non-repetitive off-track, which improves the data reliability of the equipment. improved. In addition, we were able to suppress noise and vibration caused by eccentricity.

In addition, in removable fixed magnetic disk devices,
The relative position of the disc and spindle motor is uniquely stable,
In order to reproduce this, we were able to drastically reduce the off-traffic load and improve the positioning accuracy of the disk device.

The present invention in a magnetic disk device employing surface servo will be described in detail.

Only the magnetic disk of the present invention has a drive section having the same shape and dimensions as the main shaft motor knob, and is written on a dedicated disk. Write the servo information using the servo track writer (STW). A disk on which servo information has been written can be installed in the main shaft motor hub of a magnetic disk device, and the servo signal can be read by the head of the disk device to control the head. In the case of this method, since only a single disk is written using STW, excess dust does not enter the servo track writer, so no dust adheres to the disk, and dust can be prevented from getting mixed in when it is installed into a magnetic disk. , we were able to create an extremely clean device, eliminating the occurrence of defects and head crashes. It also prevented scratches on the STW head.

Furthermore, it is now possible to write servo information on multiple disks at once, and by simply installing the written disk into a magnetic disk device, a servo track that is concentric with the center of rotation can be achieved without eccentricity, which is different from conventional magnetic disks. It was possible to manufacture a magnetic disk device with a servo surface with the same precision as the device easily and in a short time, and for the first time mass production of surface servo magnetic disk devices was realized. This also made it possible to reduce the cost of the device.

FIG. 7 shows an explanatory diagram of the casing of the magnetic disk device of the present invention.

In the magnetic disk device of the present invention, a disk on which servo information has already been written is simply installed in the device, so it is not necessary to cut out the side surface of the casing 76 so as not to interfere with the moving part of the STW as in the conventional case. Therefore, the height H of the side surface of the casing can be configured to be as high as possible. Here, the main shaft motor 75,
Head support means 72, data 1lj71, servo surface 70
, Dataherad77.

By making the sides of the housing higher in this way, the rigidity can be increased, and the low-frequency resonance that is harmful to servo control can be eliminated or shifted to a high-frequency region, allowing the servo circuit to have a sufficiently wide band, which allows the head Positioning accuracy is improved, speed control accuracy is improved, and mis-seeks are eliminated.
The reliability of magnetic disk drives has improved.

Furthermore, since the joint surface between the casing of the magnetic disk device and the chamber 79 can be located far from the magnetic disk and the head, it is possible to prevent radiation noise from entering the head and improve the data reliability of the device.

FIG. 8 is an explanatory diagram showing the relationship between the position of the servo surface and the thermal off-track of the magnetic disk device of the present invention. With the present invention, it is possible to position the servo surface approximately in the middle of the stacked disks without any problems.

As shown in the figure, one surface of the intermediate disk among the three disks is a servo surface 80, and the corresponding head is a servo head 87.
shall be. Other data surface 81, data head 88
It is. Now, the casing 86 has become thermally non-uniform due to the heat generated by the magnetic disk device circuitry, etc., and as a result, it has become distorted as shown in the figure, causing the head fixed to the head support means 82 to be tilted, causing misalignment between the heads. That is, a deviation of l occurs between the uppermost head and the lowermost head, and when the uppermost surface is a servo surface as in the conventional case, the data head on the lowermost surface has an off-track of I.

However, in the present invention, the servo surface can be placed in the middle, so the off-track between the heads is processed on the lower head and distributed to K on the upper head, making it possible to extremely reduce the amount of off-track, and thus the data Improved reliability. For this reason, there is almost no need to use a data surface servo in combination, which makes it possible to simplify the circuit, and because there is no need for off-track correction when switching heads, it has been possible to dramatically improve the data transfer speed.

Furthermore, since the amount of off-track is small even when data surface servo is used, the time required for correction is short, making high-speed data transfer possible.

〔Effect of the invention〕

As described above, according to the present invention, 1) The spindle motor hub and the inner periphery of the magnetic disk are engaged in three places and can be mounted without eccentricity, and because they rotate, the life of the spindle motor is not reduced and mechanical reliability is improved. .

2) Since no eccentricity occurs, no noise or vibration is generated, and the user of the host system is no longer uncomfortable. It was also possible to prevent deterioration of head positioning accuracy due to vibration.

3) Eccentricity and whirling are reduced, and bearing deflection is eliminated, reducing non-repeatable off-track and improving data reliability of the device.

4) Off-track of a removable fixed magnetic disk device can be extremely reduced, improving data reliability.

5) Large, high-rigidity bearings, balancing after disc assembly, and high-precision hubs are no longer required, reducing device assembly man-hours.
We were able to achieve lower prices and smaller size.

6) Improved cleanliness inside the surface servo magnetic disk device to prevent head and disk damage and improve data reliability.

7) - By simply writing servo signals to multiple disks at the same time and incorporating them into each magnetic disk device, you can obtain a servo surface with the same accuracy as a conventional surface servo magnetic disk device, making a leap forward in disk device production. It was easy and quick to perform, making it possible to mass-produce surface servo disk devices and contributing to lower prices.

8) Since the side height of the magnetic disk device housing is sufficient, it is possible to increase the rigidity of the device, reduce mechanical resonance points that are harmful to servo control, and make it possible to shift to a high frequency band, resulting in sufficiently stable servo control. control has been realized, allowing highly accurate positioning and highly reliable seek.

9) Expensive vibration isolating materials and reinforcing materials are not required, making the device smaller, lighter, and cheaper.

10) Reduced the influence of radiation noise entering from the joint surface of the casing and chamber, increasing the reliability of the data of the device.

11) Since the servo surface can be set on the intermediate disk of the stacked disks, off-track distribution between the disks is reduced, and the reliability of the device for suppressing errors due to off-track is increased.

12) With 11), there is almost no need to use a data surface servo, which simplifies the circuit, lowers the price, and eliminates the time required for off-track correction when switching heads, increasing data transfer speed. I was able to increase it dramatically.

13) Even when data surface servo is used, off-track correction time can be shortened and high-speed data transfer is possible.

It has the effects shown above.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the positioning of the main shaft motor hub of the fixed magnetic disk device of the present invention and the inner circumference of the disk. FIG. 2 is an explanatory diagram of the installation of a disk into the main shaft motor and eccentricity of a conventional fixed disk device. FIG. 3 is an explanatory diagram showing the relationship between the movable part of the STW of a conventional planar servo disk device and the disk device housing. FIG. 4 is an explanatory diagram of the principle used for positioning according to the present invention. FIG. 5 is an explanatory diagram showing another example of the present invention. FIG. 6 is an explanatory diagram showing another example of the present invention. FIG. 7 is an explanatory diagram of the casing of the magnetic disk device of the present invention. FIG. 8 is an explanatory diagram showing the relationship between the position of the servo surface and the thermal off-track of the magnetic disk device of the present invention. 1, 21.41. 51. 61 ... Main shaft motor hub 2.23, 46, 52.62 ... Center of rotation (center of gravity) of main shaft motor hub 8, 58. 103...Flexible part 9, 20.40. 50.60. 100... Magnetic disk, disk 22... Magnetic disk rotation center 47... Disk center of gravity 24.33, head 35, 75.85... Main shaft motor 36.76.86... Housing ( Magnetic disk device housing) 37.38・Disk surface 34・Clock head 32 fist・STW actuator 4.2. 53. 63 68 ・ 72゜71゜70゜77゜79 Inner periphery of disk...Flexible member 82, head support means 8, top surface 80, servo surface 88, data head 87, servo head housing Fist Chamber Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Kizobe Suzuki (and 1 other person) N5 Figure 10 Figure 6 Figure 8

Claims (1)

[Scope of Claims] 1) The main spindle motor hub has a hole in the center for attachment to the main spindle motor hub, and has a hole shape that engages and positions the substantially cylindrical surface of the main spindle motor hub at three locations, and at least one surface has a hole shape for engaging and positioning the main spindle motor hub at three locations. A fixed magnetic disk device characterized by mounting at least one magnetic disk on which a servo signal for head positioning is written. 2) The fixed magnetic disk device according to claim 1, wherein one of the three engagement positioning locations is flexible. 3) The fixed magnetic disk device according to claim 1, wherein one of the three positions for engaging and positioning is formed by means other than a flexible magnetic disk.