US20020071204A1 - Magnetic disk apparatus - Google Patents
Magnetic disk apparatus Download PDFInfo
- Publication number
- US20020071204A1 US20020071204A1 US10/072,879 US7287902A US2002071204A1 US 20020071204 A1 US20020071204 A1 US 20020071204A1 US 7287902 A US7287902 A US 7287902A US 2002071204 A1 US2002071204 A1 US 2002071204A1
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- US
- United States
- Prior art keywords
- hub
- opening
- spindle motor
- disk
- bearing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/10—Construction relative to lubrication
- F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
- F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
- F16C33/107—Grooves for generating pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/04—Sliding-contact bearings for exclusively rotary movement for axial load only
- F16C17/045—Sliding-contact bearings for exclusively rotary movement for axial load only with grooves in the bearing surface to generate hydrodynamic pressure, e.g. spiral groove thrust bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/10—Construction relative to lubrication
- F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
- F16C33/103—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing
- F16C33/1035—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing by a magnetic field acting on a magnetic liquid
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/20—Driving; Starting; Stopping; Control thereof
- G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B25/00—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus
- G11B25/04—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card
- G11B25/043—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card using rotating discs
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/14—Reducing influence of physical parameters, e.g. temperature change, moisture, dust
- G11B33/148—Reducing friction, adhesion, drag
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
- H02K5/167—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using sliding-contact or spherical cap bearings
- H02K5/1675—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using sliding-contact or spherical cap bearings radially supporting the rotary shaft at only one end of the rotor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2370/00—Apparatus relating to physics, e.g. instruments
- F16C2370/12—Hard disk drives or the like
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/14—Reducing influence of physical parameters, e.g. temperature change, moisture, dust
- G11B33/1446—Reducing contamination, e.g. by dust, debris
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/14—Reducing influence of physical parameters, e.g. temperature change, moisture, dust
- G11B33/1486—Control/regulation of the pressure, e.g. the pressure inside the housing of a drive
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/4902—Electromagnet, transformer or inductor
- Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
- Y10T29/49025—Making disc drive
Definitions
- the present invention relates to a magnetic disk equipment using a dynamic pressure slide bearing.
- the magnetic disk equipment needs high recording density, large capacity, small size and high speed.
- the magnetic disk equipment, that is used for a personal computer needs high speed and high precision of the rotation more and more.
- Ball bearings were used for the motor for a magnetic disk drive conventionally. Improvement of the manufacture precision and the lubrication, etc. in the ball bearings has raised rotary precision.
- the ball bearings have a limit to the improvement of manufacture precision.
- Rotary precision is deteriorated by wear of bearing surfaces.
- a transformation is easy to arise in the inside and outside ring in assembly of a motor, when the ball bearings of a small diameter are used for miniaturization of equipment.
- the limit of high recording density arises by the above reason.
- This motor is disclosed in the Japanese patent Laid-open print No. 5-336697 official gazette.
- the motor that adopts a dynamic pressure slide bearing has the problem of the oil leakage from the bearing part and scattering of oil particles.
- the seal structure of a dynamic pressure slide bearing is disclosed to the Japanese patent Laid-open print No. 7-310830 official gazette.
- the magnetic disk equipment for the personal computer of a desk top type and a notebook type is easy to handle it, and it is necessary to endure an impact when it falls from the top of a desk and during a portage.
- magnetic disk equipment receives 500-1000 G impact, the intensity of the structure parts is deteriorated, and measured precision changes.
- the magnetic disk equipment using dynamic pressure slide bearing equipment the oil scattering from the bearing equipment occurs, and the function is sometimes harmed.
- Another object of the invention to provide the magnetic disk equipment with high reliability that does not generate the fluid power and the fluctuation of the fluid power that occurs by the rotation of the magnetic desk.
- the present invention has a motor drive part and magnetic fluid bearing structure using the dynamic pressure slide bearing inside a hub on which the magnetic disk is mounted.
- a passage of the axial direction for air circulation is built in the hub.
- magnetic fluid is used as a lubrication fluid of the bearing.
- magnetic fluid is magnetized with the permanent magnet arranged in the bearing equipment.
- a hollow of a ring-form is provided in the hub in the neighborhood of the connection of the hub and the rotary axis. In case magnetic fluid leaks outside the bearing equipment by impact force that operates on magnetic disk equipment, the magnetic fluid leaked is held in this hollow. As a result magnetic fluid is prevented from scattering.
- FIG. 1 is the part vertical sectional view of the magnetic disk equipment of the present invention.
- FIG. 2 is the part vertical sectional view of the filter structure of the passage formed to the hub for the air circulation of the present invention.
- FIG. 3 is the part vertical sectional view of the filter structure of the passage formed to the hub for the air circulation of the present invention.
- FIG. 4 shows the groove shape of the upper end face of the bearing case for the dynamic pressure occurrence of the bearing equipment opening of the present invention.
- FIG. 5 shows the groove shape of the upper end face of the bearing case for the dynamic pressure occurrence of the bearing equipment opening of the present invention.
- FIG. 6 is the vertical sectional view of the seal ring and shows the spiral groove of the inside circuit (on the face that is opposed to the rotary axis of the seal ring) of the present invention.
- FIG. 7 is the part vertical sectional view of a magnetic disk equipment not having a hole in the hub with respect to FIG. 1.
- FIG. 8 is the part vertical sectional view of the magnetic disk equipment of other embodiment of the present invention.
- case 24 of magnetic disk equipment is comprised of casing 15 and casing cover 20 . Part of case 24 is omitted in this figure.
- the transducer is arranged in the surface of the magnetic disk for recording information in the magnetic disk and for reproducing information recorded in the magnetic disk.
- the transducer is positioned to a truck where the information is recorded or reproduced in.
- a positioning device to position the transducer is omitted.
- motor (spindle motor) 25 for the drive of magnetic disk 13 is arranged.
- Motor 25 is composed of multipolar permanent magnet 10 provided in the inside circuit of hub 11 of the cup shape, armature winding 9 for magnetic field generation provided on the casing 15 side and armature iron core 8 . That is, armature iron core 8 is adjusted to the projection part of casing 15 .
- Seal ring 7 , dynamic pressure radial bearing 2 , permanent magnet 3 provided between dynamic pressure bearings, stopper ring 16 and thrust bearing 5 are arranged in the bearing equipment along rotary axis 1 from the side (the upper side of the figure) of the opening of bearing case 6 .
- Magnetic fluid 4 for lubrication is filled between rotary axis 1 and radial bearing 2 , between rotary axis 1 and thrust bearing 5 .
- Spiral groove 17 of the shape that is shown in FIG. 4 or FIG. 5 is prepared in the opening end part of this bearing case 6 .
- this spiral groove 17 returns the leaked magnetic fluid inside seal ring 7 by using the negative pressure or pumping that occurs by the turn of rotary axis 1 .
- the scattering to the side of motor 25 of magnetic fluid 4 can be prevented.
- spiral groove 21 is prepared in the inside face of seal ring 7 .
- Groove 21 prepared in the seal ring 7 returns magnetic fluid 4 to the bearing side.
- Rotary axis 1 press fitted to the hub 11 is supported to be able to rotate by dynamic pressure radial bearing 2 provided at both ends of permanent magnet 3 .
- permanent magnet 3 is arranged to hold magnetic fluid 4 in bearing case 6 .
- the load of the axial direction is supported by receiving the sphere part of the tip of rotary axis 1 on thrust bearing 5 .
- a magnetic disk Clamp 18 is fixed to the rotary axis 1 and hub 11 by bolt 19 .
- Stopper ring 16 held between thrust bearing 5 and radial bearing 2 is fitted in groove 26 prepared in rotary axis 1 .
- Passage 12 (hole) that connects the motor 25 side and casing cover 20 side for the air circulation penetrates the hub 11 .
- FIG. 7 The sectional view of the magnetic disk equipment is shown in FIG. 7.
- the space between casing cover 20 and hub 11 is small, and the space is about 1 mm.
- the air that is shown to arrow A flows in a conventional structure that does not prepare hole 12 in the hub 11 when magnetic disk 13 spins. Therefore, the pressure difference arises between the side of the outer periphery of the magnetic disk 13 and the center of the hub 11 . Then, the power that attracts the hub 11 to the casing cover 20 side occurs. Inside the hub 11 in which motor 25 is positioned, the air flows from arrow C to the direction of arrow B. At this time, the pressure difference arises between bearing case 6 and permanent magnet 10 . But the force that attracts the hub 11 to the motor 25 side is small than the casing cover 20 side by difference between the differences of the diameter. Therefore, the hub 11 is attracted to the casing cover 20 side.
- the magnetic attraction force is at most 100 GRF. Therefore, when the load of the axial direction that occurs by the spin of this magnetic disk 13 approaches the magnetic attraction force, the vibration displacement of the axial direction by disorder of the air on the casing cover 20 side enlarges.
- the vibration displacement by this disorder of the air is the asynchronous vibration that does not relate to the number of revolutions. This asynchronous vibration cannot be controlled by the control system of magnetic disk equipment. Therefore, when the asynchronous vibration is large, the recording density of magnetic disk 13 cannot be raised.
- the hole 12 is prepared in the hub 11 to maintain the magnetic attraction force that operates between permanent magnet 10 and armature iron core 8 , and to reduce the fluctuation load by disorder of the air.
- the axial load that acts on the hub 11 is made to balance by making the pressure on the motor 25 side balance with the pressure on the casing cover 20 side.
- the holes 12 are prepared in the hub 11 , because the flow of the air becomes the arrow direction of FIG. 1, there is also an Advantage in cooling of the motor 25 side. By raising cooling of the motor side, the bearing equipment can be cooled. Therefore, evaporation of magnetic fluid enclosed in the bearing equipment can be suppressed. As a result the life of magnetic disk equipment becomes long, and reliability of magnetic disk equipment improves.
- passage 12 (hole) for the air circulation is built, and the flow of the air that is shown in the arrow of FIG. 1 is made. Even if passage 12 (hole) for the air circulation is applied to magnetic disk equipment on which the spindle motor using a conventional roller bearings is mounted, the fluctuation load by disorder of the air can be reduced. Therefore, the Function Advantage that is similar to the case of the slide bearing of FIG. 1 is obtained.
- this pollution can be prevented by using the filter 27 , made of fluorine resin or coated fluorine resin on fiber, to cover hole 12 . While these filters 27 pass the air, liquid is not passed. Therefore, these filters 27 have the advantage that fits the purpose of the present invention.
- Filter 27 ′ can be made ring shaped against hole 12 ′ shown in FIG. 3. In this embodiment, by building passage 12 ′ for the air circulation that penetrates the axial direction in the hub 11 ′, the flow of the air arises in the arrow direction shown in FIG. 1. Because filter 27 shields the dust of bearing equipment and the motor part, the damage of magnetic disk 13 by the dust can be prevented.
- spiral grooves 17 and 21 for dynamic pressure generation are prepared in the end of the bearing case 6 and in the inside circuit of the seal ring 7 .
- spiral groove 17 for dynamic pressure generation is prepared in the end of bearing case 6 to converge on the direction that is the same as the rotary direction of axis 1 .
- the oil particle is returned to the seal ring 7 side by making the turning flow along spiral groove 17 (arrow direction of FIG. 4 and FIG. 5). As a result the oil particle that occurs because of evaporation, etc. in bearing case 6 does not scatter on the motor 25 side.
- the space between the end of bearing case 6 and the hub 11 is made small so that an occurrence of the dynamic pressure becomes easy.
- this space is 0.1 MM-0.3 MM.
- the space between the inside circuit of seal ring 7 and axis 1 is made 10 ⁇ M-30 ⁇ M, and the turning flow of the air of the arrow direction of the figure is generated in parts of the spiral groove 21 . As a result the oil particle and magnetic fluid 4 that adhered to seal ring 7 is returned to radial bearing 2 .
- Groove 17 for dynamic pressure generation can be prepared in the face of the hub 11 that is opposed to the end of bearing case 6 instead of preparing in the end of bearing case 6 . While the hub 11 rotated, the flow of the air was conducted to the radial bearing 2 side in the opening of the bearing equipment, and in the part of motor 25 the air flows in the arrow direction shown in FIG. 1. As a result the oil particle that comes out from the bearing equipment is prevented from scattering.
- hollow 23 of the ring-form in which magnetic fluid 4 is held is provided in the press fitting part of the hub 11 and axis 1 .
- the centrifugal force scatters magnetic fluid 4 .
- magnetic fluid 4 that comes out by impact force of the axial direction is held in hollow 23 .
- the hub 11 rotates the oil particle is prevented from scattering, and magnetic fluid 4 is recovered into the bearing equipment by the function of the spiral groove prepared in bearing case 6 and seal ring 7 . As a result pollution of magnetic disk 13 by the oil particle can be prevented.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Rotational Drive Of Disk (AREA)
- Sliding-Contact Bearings (AREA)
- Recording Or Reproducing By Magnetic Means (AREA)
Abstract
The hole that penetrates the axial direction in the hub, the force of the axial direction by fluid force that operates on the spindle motor is reduced during the rotation. Fluctuation of fluid power is reduced by this hole. The rotary precision of the axial direction improves. Against the oil leakage from the bearing equipment, magnetic fluid is used as a lubrication fluid of the bearing. Magnetic fluid is magnetized with the permanent magnet arranged in the bearing equipment, and oil leakage is prevented. Against scattering of the oil particle, the groove for dynamic pressure generation is in the opening of bearing equipment. The oil particle is kept inside the bearing equipment.
Description
- The present invention relates to a magnetic disk equipment using a dynamic pressure slide bearing.
- Following remarkable spread of a personal computer, the magnetic disk equipment needs high recording density, large capacity, small size and high speed. The magnetic disk equipment, that is used for a personal computer, needs high speed and high precision of the rotation more and more. Ball bearings were used for the motor for a magnetic disk drive conventionally. Improvement of the manufacture precision and the lubrication, etc. in the ball bearings has raised rotary precision.
- But the ball bearings have a limit to the improvement of manufacture precision. Rotary precision is deteriorated by wear of bearing surfaces. A transformation is easy to arise in the inside and outside ring in assembly of a motor, when the ball bearings of a small diameter are used for miniaturization of equipment. The limit of high recording density arises by the above reason. There is a motor that adopts a dynamic pressure slide bearing instead of ball bearings. This motor is disclosed in the Japanese patent Laid-open print No. 5-336697 official gazette. The motor that adopts a dynamic pressure slide bearing has the problem of the oil leakage from the bearing part and scattering of oil particles. The seal structure of a dynamic pressure slide bearing is disclosed to the Japanese patent Laid-open print No. 7-310830 official gazette.
- The magnetic disk equipment for the personal computer of a desk top type and a notebook type is easy to handle it, and it is necessary to endure an impact when it falls from the top of a desk and during a portage. When magnetic disk equipment receives 500-1000 G impact, the intensity of the structure parts is deteriorated, and measured precision changes. In case of the magnetic disk equipment using dynamic pressure slide bearing equipment, the oil scattering from the bearing equipment occurs, and the function is sometimes harmed.
- The structure that refers to the seal of bearing equipment is disclosed to the Japanese patent Laid-open print No. 8-310830 official gazette. This seal is used for the oil leakage measures of bearing equipment. But it is not considered against oil pollution of magnetic disk equipment. To increase rotary precision, a motor using a dynamic pressure bearing is disclosed to the Japanese patent Laid-open print No. 5-336697 official gazette. But when a spindle motor is installed in magnetic disk equipment and it is rotated, fluid power operates on a spindle motor in the axial direction. This fluid power is generated by the flow of the air between rotary parts such as the magnetic disk and the stillness part. At this time, because the flow of the air is not uniform, the fluid power fluctuates and sometimes harms the rotary precision of the axial direction.
- Therefore, the fluid power of the axial direction that acts on the spindle motor for high recording density of the magnetic disk equipment must be reduced. A conventional spindle motor for the magnetic disk drive is positioned to the axial direction by force that attracts magnetically. But a conventional spindle motor does not consider the fluid power and the fluctuation of the fluid power that occur by the rotation of the magnetic desk.
- It is an object of the invention to prevent pollution of the magnetic disk by the oil leakage and scattering of the oil particles from the bearing equipment.
- Another object of the invention to provide the magnetic disk equipment with high reliability that does not generate the fluid power and the fluctuation of the fluid power that occurs by the rotation of the magnetic desk.
- The present invention has a motor drive part and magnetic fluid bearing structure using the dynamic pressure slide bearing inside a hub on which the magnetic disk is mounted. A passage of the axial direction for air circulation is built in the hub. As a result, the fluid power and the fluctuation of the fluid power of the axial direction that acts on the spindle motor during the rotation is reduced, and the rotary precision of the axial direction is improved. To prevent the oil leakage from the bearing equipment, magnetic fluid is used as a lubrication fluid of the bearing. And magnetic fluid is magnetized with the permanent magnet arranged in the bearing equipment.
- By preparing the spiral groove to generate the dynamic pressure in the opening of bearing equipment or in the face of hub that is opposed to this opening, the oil particle is prevented from rushing outside the bearing equipment. In case magnetic fluid leaks outside the bearing equipment by impact force that operates on magnetic disk equipment, the magnetic fluid leaked is recovered in the bearing equipment along the spiral groove by using the rotation of hub.
- A hollow of a ring-form is provided in the hub in the neighborhood of the connection of the hub and the rotary axis. In case magnetic fluid leaks outside the bearing equipment by impact force that operates on magnetic disk equipment, the magnetic fluid leaked is held in this hollow. As a result magnetic fluid is prevented from scattering.
- The passage for the air circulation that penetrates the axial direction was built in the hub on which the magnetic disk is mounted. As a result the fluid power of the axial direction that acts on the hub and the fluctuation of this fluid power can be suppressed. Because the rotary precision of the axial direction can be raised, the recording density of magnetic disk equipment improves. The groove for dynamic pressure generation was prepared in the opening of bearing equipment. The hollow of a ring-form was provided in the press fitting part of the hub and the axis. As a result, leakage of magnetic fluid that was enclosed in the bearing equipment and scattering of the oil particles can be prevented during the rotation. Leakage of magnetic fluid that was enclosed in the bearing equipment and scattering of the oil particle can be prevented even if impact power operates on magnetic disk equipment. Pollution of the magnetic disk is prevented, the precise spin of the magnetic disk can be maintained, and the life of the magnetic disk becomes long. By the above, magnetic disk equipment with a high recording density and with high reliability can be provided.
- FIG. 1 is the part vertical sectional view of the magnetic disk equipment of the present invention.
- FIG. 2 is the part vertical sectional view of the filter structure of the passage formed to the hub for the air circulation of the present invention.
- FIG. 3 is the part vertical sectional view of the filter structure of the passage formed to the hub for the air circulation of the present invention.
- FIG. 4 shows the groove shape of the upper end face of the bearing case for the dynamic pressure occurrence of the bearing equipment opening of the present invention.
- FIG. 5 shows the groove shape of the upper end face of the bearing case for the dynamic pressure occurrence of the bearing equipment opening of the present invention.
- FIG. 6 is the vertical sectional view of the seal ring and shows the spiral groove of the inside circuit (on the face that is opposed to the rotary axis of the seal ring) of the present invention.
- FIG. 7 is the part vertical sectional view of a magnetic disk equipment not having a hole in the hub with respect to FIG. 1.
- FIG. 8 is the part vertical sectional view of the magnetic disk equipment of other embodiment of the present invention.
- As follows, the embodiment of the present invention is explained.
- In FIG. 1,
case 24 of magnetic disk equipment is comprised ofcasing 15 andcasing cover 20. Part ofcase 24 is omitted in this figure. The transducer is arranged in the surface of the magnetic disk for recording information in the magnetic disk and for reproducing information recorded in the magnetic disk. The transducer is positioned to a truck where the information is recorded or reproduced in. In FIG. 1, a positioning device to position the transducer is omitted. In thiscase 24, motor (spindle motor) 25 for the drive ofmagnetic disk 13 is arranged.Motor 25 is composed of multipolarpermanent magnet 10 provided in the inside circuit ofhub 11 of the cup shape, armature winding 9 for magnetic field generation provided on thecasing 15 side andarmature iron core 8. That is,armature iron core 8 is adjusted to the projection part ofcasing 15. -
Seal ring 7, dynamic pressureradial bearing 2,permanent magnet 3 provided between dynamic pressure bearings,stopper ring 16 and thrustbearing 5 are arranged in the bearing equipment alongrotary axis 1 from the side (the upper side of the figure) of the opening of bearingcase 6.Magnetic fluid 4 for lubrication is filled betweenrotary axis 1 andradial bearing 2, betweenrotary axis 1 and thrustbearing 5. -
Spiral groove 17 of the shape that is shown in FIG. 4 or FIG. 5 is prepared in the opening end part of thisbearing case 6. In casemagnetic fluid 4 leaks in the space between the end of bearingcase 6 and the face ofhub 11, thisspiral groove 17 returns the leaked magnetic fluid insideseal ring 7 by using the negative pressure or pumping that occurs by the turn ofrotary axis 1. As a result the scattering to the side ofmotor 25 ofmagnetic fluid 4 can be prevented. - In the inside face of
seal ring 7,spiral groove 21 is prepared.Groove 21 prepared in theseal ring 7 returnsmagnetic fluid 4 to the bearing side. -
Rotary axis 1 press fitted to thehub 11 is supported to be able to rotate by dynamic pressureradial bearing 2 provided at both ends ofpermanent magnet 3. To holdmagnetic fluid 4 in bearingcase 6,permanent magnet 3 is arranged. The load of the axial direction is supported by receiving the sphere part of the tip ofrotary axis 1 onthrust bearing 5. Amagnetic disk Clamp 18 is fixed to therotary axis 1 andhub 11 bybolt 19.Stopper ring 16 held between thrust bearing 5 andradial bearing 2 is fitted ingroove 26 prepared inrotary axis 1. As a resultrotary axis 1 does not come out to the axial direction. Passage 12 (hole) that connects themotor 25 side and casing cover 20 side for the air circulation penetrates thehub 11. - Several
magnetic disks 13 install to the outer periphery of thehub 11 to keep the specified space byspacer 14. The top ofmagnetic disk 13 is fixed withmagnetic disk clamp 18. - The sectional view of the magnetic disk equipment is shown in FIG. 7.
- As shown in FIG. 7, the space between
casing cover 20 andhub 11 is small, and the space is about 1 mm. The air that is shown to arrow A flows in a conventional structure that does not preparehole 12 in thehub 11 whenmagnetic disk 13 spins. Therefore, the pressure difference arises between the side of the outer periphery of themagnetic disk 13 and the center of thehub 11. Then, the power that attracts thehub 11 to thecasing cover 20 side occurs. Inside thehub 11 in which motor 25 is positioned, the air flows from arrow C to the direction of arrow B. At this time, the pressure difference arises between bearingcase 6 andpermanent magnet 10. But the force that attracts thehub 11 to themotor 25 side is small than thecasing cover 20 side by difference between the differences of the diameter. Therefore, thehub 11 is attracted to thecasing cover 20 side. - Disorder of the air on the
casing cover 20 side arises bymagnetic disk 13 andmagnetic disk clamp 18. It acts as a fluctuation load of the axial direction. This fluctuation load is shown to arrow D. On the other hand, magnet thrust power is given to thehub 11 by force (about 100 GRF) that operates betweenpermanent magnet 10 andarmature iron core 8. But the bearing load that acts on thethrust bearing 5 becomes smaller than the thrust load at the time of standing still because the force that works by the pressure difference on thecasing cover 20 side becomes the reverse direction. - The magnetic attraction force is at most 100 GRF. Therefore, when the load of the axial direction that occurs by the spin of this
magnetic disk 13 approaches the magnetic attraction force, the vibration displacement of the axial direction by disorder of the air on thecasing cover 20 side enlarges. The vibration displacement by this disorder of the air is the asynchronous vibration that does not relate to the number of revolutions. This asynchronous vibration cannot be controlled by the control system of magnetic disk equipment. Therefore, when the asynchronous vibration is large, the recording density ofmagnetic disk 13 cannot be raised. - In this embodiment, the
hole 12 is prepared in thehub 11 to maintain the magnetic attraction force that operates betweenpermanent magnet 10 andarmature iron core 8, and to reduce the fluctuation load by disorder of the air. As a result the axial load that acts on thehub 11 is made to balance by making the pressure on themotor 25 side balance with the pressure on thecasing cover 20 side. When theholes 12 are prepared in thehub 11, because the flow of the air becomes the arrow direction of FIG. 1, there is also an Advantage in cooling of themotor 25 side. By raising cooling of the motor side, the bearing equipment can be cooled. Therefore, evaporation of magnetic fluid enclosed in the bearing equipment can be suppressed. As a result the life of magnetic disk equipment becomes long, and reliability of magnetic disk equipment improves. - In this embodiment, passage12 (hole) for the air circulation is built, and the flow of the air that is shown in the arrow of FIG. 1 is made. Even if passage 12 (hole) for the air circulation is applied to magnetic disk equipment on which the spindle motor using a conventional roller bearings is mounted, the fluctuation load by disorder of the air can be reduced. Therefore, the Function Advantage that is similar to the case of the slide bearing of FIG. 1 is obtained.
- With the magnetic disk equipment of this embodiment. Using dynamic pressure
radial bearing 2 that has three circular arcs or herringbone type dynamic pressure bearing 2, thehub 11 can maintain the high precision rotation. But as it is mentioned above, the flow of the air arises in the arrow direction shown in FIG. 1 on themotor 25 side. When the oil particle occurs by evaporation ofmagnetic fluid 4 enclosed in bearing equipment, the oil particle comes out to themagnetic disk 13 side along the flow of the air, andmagnetic disk 13 is polluted. - As shown in FIG. 2, this pollution can be prevented by using the
filter 27, made of fluorine resin or coated fluorine resin on fiber, to coverhole 12. While thesefilters 27 pass the air, liquid is not passed. Therefore, thesefilters 27 have the advantage that fits the purpose of the present invention.Filter 27′ can be made ring shaped againsthole 12′ shown in FIG. 3. In this embodiment, by buildingpassage 12′ for the air circulation that penetrates the axial direction in thehub 11′, the flow of the air arises in the arrow direction shown in FIG. 1. Becausefilter 27 shields the dust of bearing equipment and the motor part, the damage ofmagnetic disk 13 by the dust can be prevented. - In the slide bearing equipment, the occurrence of the oil particle by evaporation of the lubricant enclosed in the bearing equipment is not avoided. Therefore, long-term use decreases
magnetic fluid 4 for lubrication enclosed in bearing equipment. Whenmagnetic fluid 4 decreases, the dynamic pressure function of the bearing is harmed. When the dynamic pressure Function of the bearing is harmed, the vibration occurs by the oil shortage, and rotary precision deteriorates. - As shown in FIG. 4, FIG. 5 and FIG. 6, to prevent
magnetic fluid 4 from decreasing by scattering, in this embodiment,spiral grooves bearing case 6 and in the inside circuit of theseal ring 7. - In case there is not
spiral groove 17 for dynamic pressure generation in the end of bearingcase 6, the rotation of thehub 11 generates the turning flow of the air inside thehub 11 in which motor 25 was arranged. And, as shown in FIG. 7, the air flows from arrow C to the direction of arrow B, and the pressure difference arises betweenaxis 1 andpermanent magnet 10. Therefore, the air of the end part of bearingcase 6 becomes the turning flow. The oil particle that evaporated in bearingcase 6 mixes in this turning flow and scatters on themotor 25 side. - In this embodiment,
spiral groove 17 for dynamic pressure generation is prepared in the end of bearingcase 6 to converge on the direction that is the same as the rotary direction ofaxis 1. The oil particle is returned to theseal ring 7 side by making the turning flow along spiral groove 17 (arrow direction of FIG. 4 and FIG. 5). As a result the oil particle that occurs because of evaporation, etc. in bearingcase 6 does not scatter on themotor 25 side. - The space between the end of bearing
case 6 and thehub 11 is made small so that an occurrence of the dynamic pressure becomes easy. For example, this space is 0.1 MM-0.3 MM. The space between the inside circuit ofseal ring 7 andaxis 1 is made 10 μM-30 μM, and the turning flow of the air of the arrow direction of the figure is generated in parts of thespiral groove 21. As a result the oil particle andmagnetic fluid 4 that adhered to sealring 7 is returned toradial bearing 2. -
Groove 17 for dynamic pressure generation can be prepared in the face of thehub 11 that is opposed to the end of bearingcase 6 instead of preparing in the end of bearingcase 6. While thehub 11 rotated, the flow of the air was conducted to theradial bearing 2 side in the opening of the bearing equipment, and in the part ofmotor 25 the air flows in the arrow direction shown in FIG. 1. As a result the oil particle that comes out from the bearing equipment is prevented from scattering. - In this embodiment, when the impact operates on the axial direction,
axis 1 is prevented from getting out bystopper ring 16. Butmagnetic fluid 4 enclosed in bearing equipment overcomes holding power by magnetic attraction force ofpermanent magnet 3 and sometimes comes out to the end part of bearingcase 6. The space betweenseal ring 7 andaxis 1 and the space betweenbearing case 6 and thehub 11 is made small like above. In casemagnetic fluid 4 comes out, it also can be stopped to the neighborhood of the end part ofseal ring 7. - In the embodiment shown in FIG. 8, hollow23 of the ring-form in which
magnetic fluid 4 is held is provided in the press fitting part of thehub 11 andaxis 1. In case the hollow 23 is not provided, when thehub 11 rotates, the centrifugal force scattersmagnetic fluid 4. In this embodiment,magnetic fluid 4 that comes out by impact force of the axial direction is held in hollow 23. When thehub 11 rotates, the oil particle is prevented from scattering, andmagnetic fluid 4 is recovered into the bearing equipment by the function of the spiral groove prepared in bearingcase 6 andseal ring 7. As a result pollution ofmagnetic disk 13 by the oil particle can be prevented.
Claims (14)
1. A spindle motor used in an information storage apparatus at least to reproduce an information from a rotating disk comprising:
a member which form a part of a case on which the spindle motor is installed;
a rotary axis;
a bearing device which support said rotary axis to be able to rotate against said member;
a cup-shaped hub to install the disk, which having a motor to rotate the disk and said bearing device in the inside, and
a passage for the air circulation, which connects the inside of said hub with the outside.
2. A spindle motor as claimed in claim 1 , wherein an outside opening of said passage is arranged at an portion of said hub which is situated on opposite side of said member with respect to said disk.
3. A spindle motor as claimed in claim 1 , wherein said disk is a plurality of magnetic disk stacked up on said hub, and an outside opening of said passage is arranged at an portion of said hub which is situated on opposite side of said member with respect to the disk stacked on the top.
4. A spindle motor as claimed in claim 1 , wherein
said bearing device is comprising a seal ring, a radial bearing, a permanent magnet, another radial bearing and a thrust bearing arranged along said rotating shaft from a opening side;
said radial bearings are dynamic pressure sliding bearings; and
magnetic fluid is used as a lubricant for bearings.
5. A spindle motor as claimed in claim 1 , wherein a filter is positioned in said passage.
6. An information storage apparatus at least to reproduce an information from a disk rotated by a spindle motor as claimed in claim 1 , wherein a cover is provided to cover said disk, and an outside opening of said passage is provided so as to connect the inside of the hub with a space formed by said disk and said cover.
7. A spindle motor used in an information storage apparatus at least to reproduce an information from a rotating disk comprising:
a member which form a part of a case on which the spindle motor is installed;
a rotary axis;
a bearing device which support said rotary axis to be able to rotate against said member;
a cup-shaped hub to install the disk, which having said bearing device in the inside;
a motor structurally connecting to said rotary axis; and
a means for forcing back the fruid leaked from said bearing device into said bearing device, which is adjacent to an opening of said bearing device.
8. A spindle motor as claimed in claim 7 , wherein said means is a spiral groove forming either in an opening of said bearing device or on a surface of said hub opposite to said opening.
9. A spindle motor as claimed in claim 7 , wherein said means is a spiral groove forming in said opening of said bearing device, and a annular recess is formed on a surface of said hub opposite to said opening.
10. A spindle motor as claimed in claim 7 , wherein said means is a spiral groove forming on an inner surface of a seal ring provided at a side of said opening.
11. An information storage apparatus at least to reproduce an information from a disk rotated by a spindle motor as claimed in claim 7 , wherein a cover is provided to cover said disk.
12. A spindle motor as claimed in claim 1 , wherein a spiral groove is formed either in an opening of said bearing device or on a surface of said hub opposite to said opening.
13. A spindle motor as claimed in claim 1 , wherein a spiral groove is formed forming on an inner surface of a seal ring provided at a side of said opening.
14. A spindle motor as claimed in claim 1 , wherein
a member which form a part of a case on which the spindle motor is installed;
a rotary axis;
a bearing device which support said rotary axis to be able to rotate against said member;
a cup-shaped hub to install the disk, which having a motor to rotate the disk and said bearing device in the inside, and
a passage for the air circulation, which connects the inside of said hub with the outside.
said bearing device comprising a seal ring, a radial bearing, a permanent magnet, another radial bearing and a thrust bearing arranged along said rotating shaft from a side of an opening;
said radial bearings are dynamic pressure sliding bearings; magnetic fluid is used as a lubricant for bearings;
said disk is a plurality of magnetic disk stacked up on said hub in the direction of the axis of rotation;
a spiral groove is formed either in an opening of said bearing device or on a surface of said hub opposite to said opening;
a spiral groove is formed forming on an inner surface of a seal ring provided at a side of said opening;
said passage is provided with said hub as a penetration hole of the axial direction that connects the inside and the outside the hub;
a filter made of a fluorine resin or comprising fibers coated with a fluorocarbon resin is positioned in said penetration hole: and
whereby said spiral groove force back the fruid leaked from said bearing device into said bearing device.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/072,879 US20020071204A1 (en) | 1998-09-03 | 2002-02-12 | Magnetic disk apparatus |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10-249293 | 1998-09-03 | ||
JP10249293A JP2000076779A (en) | 1998-09-03 | 1998-09-03 | Magnetic disk device |
US09/388,439 US6356408B1 (en) | 1998-09-03 | 1999-09-02 | Magnetic disk apparatus, including spindle motor having air flow passage in hub for pressure balance |
US10/072,879 US20020071204A1 (en) | 1998-09-03 | 2002-02-12 | Magnetic disk apparatus |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/388,439 Continuation US6356408B1 (en) | 1998-09-03 | 1999-09-02 | Magnetic disk apparatus, including spindle motor having air flow passage in hub for pressure balance |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020071204A1 true US20020071204A1 (en) | 2002-06-13 |
Family
ID=17190827
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/388,439 Expired - Fee Related US6356408B1 (en) | 1998-09-03 | 1999-09-02 | Magnetic disk apparatus, including spindle motor having air flow passage in hub for pressure balance |
US10/072,879 Abandoned US20020071204A1 (en) | 1998-09-03 | 2002-02-12 | Magnetic disk apparatus |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/388,439 Expired - Fee Related US6356408B1 (en) | 1998-09-03 | 1999-09-02 | Magnetic disk apparatus, including spindle motor having air flow passage in hub for pressure balance |
Country Status (3)
Country | Link |
---|---|
US (2) | US6356408B1 (en) |
JP (1) | JP2000076779A (en) |
TW (1) | TW442780B (en) |
Cited By (4)
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US20040061404A1 (en) * | 2002-09-27 | 2004-04-01 | Nidec Corporation | Recording disk drive motor, recording disk drive employing the motor, a method of manufacturing a stator used in the recording disk drive motor, and core plate that is used in the manufacture of the stator |
WO2006013417A1 (en) * | 2004-07-28 | 2006-02-09 | Minebea Co., Ltd. | Fluid dynamic pressure bearing, spindle motor provided with the fluid dynamic pressure bearing, and recording disk drive device provided with the fluid dynamic pressure bearing |
US20060215312A1 (en) * | 2005-03-28 | 2006-09-28 | Nidec Corporation | Spindle Motor and Recording Disk Driving Apparatus Having the Spindle Motor |
US9194434B2 (en) | 2013-09-10 | 2015-11-24 | Nidec Corporation | Spindle motor and disk drive apparatus |
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JP2001266473A (en) * | 2000-03-23 | 2001-09-28 | Tokyo Parts Ind Co Ltd | Spindle motor having disk loading section |
GB2379560B (en) * | 2001-03-30 | 2005-12-14 | Sunonwealth Electr Mach Ind Co | Supporting structure for a rotor |
TW519259U (en) * | 2001-08-31 | 2003-01-21 | Asia Vital Components Co Ltd | Improved structure of DC fan bearing fixation device |
KR100468721B1 (en) * | 2002-03-25 | 2005-01-29 | 삼성전자주식회사 | Hard disk drive having an air flow accelerating device |
US6838795B2 (en) * | 2002-05-01 | 2005-01-04 | Seagate Technology Llc | Low velocity, high pressure thrust pump |
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US8345377B2 (en) * | 2009-12-29 | 2013-01-01 | Hgst, Netherlands B.V. | Aerodynamic device directing pressurized airflow to ports in the device for aerostatic sealing in a hard disk drive(HDD) |
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US8979512B2 (en) * | 2011-12-05 | 2015-03-17 | Asia Vital Components (Chengdu) Co., Ltd. | Oil-retaining bearing having magnetic stabilizer |
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JP2669549B2 (en) * | 1988-12-14 | 1997-10-29 | 株式会社日立製作所 | Magnetic disk device |
JP3135684B2 (en) | 1992-06-01 | 2001-02-19 | 日本電産株式会社 | Spindle motor |
US5859745A (en) * | 1993-11-02 | 1999-01-12 | Seagate Technology, Inc. | Split ring mounting for disk drive spindle and actuator shafts |
US5499901A (en) * | 1994-03-17 | 1996-03-19 | Environamics Corporation | Bearing frame clearance seal construction for a pump |
US5834870A (en) * | 1994-04-28 | 1998-11-10 | Hitachi, Ltd. | Oil impregnated porous bearing units and motors provided with same |
JP3301034B2 (en) | 1995-05-17 | 2002-07-15 | 日本電信電話株式会社 | Glass composition |
KR19980015100A (en) * | 1996-08-20 | 1998-05-25 | 이형도 | Air cleaning method and apparatus of hard disk drive |
-
1998
- 1998-09-03 JP JP10249293A patent/JP2000076779A/en active Pending
-
1999
- 1999-08-10 TW TW088113663A patent/TW442780B/en not_active IP Right Cessation
- 1999-09-02 US US09/388,439 patent/US6356408B1/en not_active Expired - Fee Related
-
2002
- 2002-02-12 US US10/072,879 patent/US20020071204A1/en not_active Abandoned
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US20040061404A1 (en) * | 2002-09-27 | 2004-04-01 | Nidec Corporation | Recording disk drive motor, recording disk drive employing the motor, a method of manufacturing a stator used in the recording disk drive motor, and core plate that is used in the manufacture of the stator |
US6982513B2 (en) | 2002-09-27 | 2006-01-03 | Nidec Corporation | Recording disk drive motor, recording disk drive employing the motor, a method of manufacturing a stator used in the recording disk drive motor, and core plate that is used in the manufacture of the stator |
WO2006013417A1 (en) * | 2004-07-28 | 2006-02-09 | Minebea Co., Ltd. | Fluid dynamic pressure bearing, spindle motor provided with the fluid dynamic pressure bearing, and recording disk drive device provided with the fluid dynamic pressure bearing |
US20070206889A1 (en) * | 2004-07-28 | 2007-09-06 | Minebea Co.,Ltd | Fluid Dynamic Pressure Bearing, Spindle Motor Provided with the Fluid Dynamic Pressure Bearing, and Recording Disk Drive Device Provided with the Fluid Dynamic Pressure bearing |
US20060215312A1 (en) * | 2005-03-28 | 2006-09-28 | Nidec Corporation | Spindle Motor and Recording Disk Driving Apparatus Having the Spindle Motor |
US7511918B2 (en) * | 2005-03-28 | 2009-03-31 | Nidec Corporation | Spindle motor and recording disk driving apparatus having the spindle motor |
US9194434B2 (en) | 2013-09-10 | 2015-11-24 | Nidec Corporation | Spindle motor and disk drive apparatus |
Also Published As
Publication number | Publication date |
---|---|
TW442780B (en) | 2001-06-23 |
JP2000076779A (en) | 2000-03-14 |
US6356408B1 (en) | 2002-03-12 |
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