JP2001110130A - Hard disk drive dealing with static electricity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an HDD capable of preventing the damage of a machine by safely discharging static electricity generated in the rotary side member of a spindle motor to the outside. SOLUTION: The discharging of static electricity generated in the rotary side member of a spindle motor is induced only between particular one among a plurality of information media 5 placed close to one another for recording/ reproducing information, and particular one among a plurality of head assemblies 21, and discharging is prevented at other places. As a means for inducing discharging, a gap between the particular medium and the particular head assembly is set to about half or lower than a gap between the other storage medium and the head assembly. More preferably, the gap is set to 15 nm or lower. In addition, discharging is induced by selecting a material having higher conductivity than others for the particular storage medium and/or the particular head assembly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a hard disk drive (hereinafter abbreviated as HDD), and more particularly to a structure of an HDD provided with measures against static electricity.

[0002]

2. Description of the Related Art FIG. 3 shows an outline of a conventional HDD. The figure shows an HDD housed in a housing, and the HDD is composed of two main elements, ten disk units and twenty head units. The disk unit 10 further includes a spindle motor 1 rotating at a high speed of about 10,000 rpm and a plurality of storage media (hard disks) 5 having an information storage surface mounted on the outer periphery of the spindle motor 1. A plurality of head assemblies 21 for accessing an information storage surface of the storage medium 5 rotating at a high speed and recording or reproducing necessary information; a carriage 25 supporting the head assemblies 21; A head mount 28 for pivotally operating the carriage 25 so that the assembly 21 can access necessary parts of each storage medium 5.

FIG. 4 is a cross-sectional view showing a spindle motor 1 mounted with a storage medium 5 according to the prior art used for the HDD as described above. In the figure, 2 is a base,
Reference numeral 3 denotes a shaft fixed to the base 2, and reference numeral 4 denotes a ball bearing press-fitted into the shaft 3, and the ball bearing 4 rotatably supports six rotor hubs on an outer peripheral portion. The plurality of storage media 5 are mounted on the outer periphery of the rotor hub 6 at predetermined intervals so that information can be recorded / reproduced on the information storage surface, and are respectively mounted in parallel to a surface perpendicular to the axis of the shaft 3. . Reference numeral 7 denotes a stator fixed to the housing 2, and the stator 7 includes a coil 8
Are wound and face the nine rotor magnets fixed to the inner peripheral surface of the rotor hub 6.

[0004] The operation of the spindle motor 1 configured as described above is such that when the coil 8 is energized, a repulsion / attraction force acts between the stator 7 and the rotor magnet 9.
As a result, a rotational driving force of the rotor hub 6 is generated, and the rotor hub 6 rotates around the shaft 3 via the ball bearing 4 and the storage medium 5 mounted on the rotor hub 6 rotates. The necessary information is extracted from the information stored in the storage medium 5 or the required information is recorded on the storage medium 5.

With respect to the spindle motor 1 provided with the ball bearing 4 as described above, non-contact rotation with higher speed and higher accuracy is required in accordance with recent demands for miniaturization, high speed, and large capacity of a storage device. Attention has been paid to the use of a dynamic pressure bearing that can be realized, in particular, a spindle motor having a dynamic pressure gas bearing that does not generate heat even at high speed rotation and is easy to handle.

FIG. 5 is a cross-sectional view showing such a hydrodynamic gas bearing 11, wherein 12 is a base, 13 is a shaft fixed to the base 12, and 14 is the shaft 1 thereof.
A sleeve fitted with a predetermined gap on the outer peripheral surface of 3,
Reference numeral 15 denotes a thrust plate which is attached to a surface perpendicular to the axis of the shaft 13 and is arranged so as to face one axial end surface of the sleeve 14, and these constitute a dynamic pressure bearing. On the surface of the thrust plate 15 facing the end face of the sleeve 14, a groove for generating a thrust dynamic pressure indicated by a dotted line 16 is provided. The sleeve 14 is fixed to a rotor hub 17, and a plurality of storage media 5 are mounted on the outer peripheral surface of the rotor hub 17. Other configurations are the same as those shown in FIG. 4 above, and the same components are denoted by the same reference numerals.

[0007] The operation of the spindle motor 11 configured as described above is such that when the coil 8 is energized, a repulsive / attractive force acts between the stator 7 and the rotor magnet 9, thereby rotating the rotor hub 17. A driving force is generated, and the sleeve 14 fixed to the rotor hub 17 rotates about the shaft 13, and a radial dynamic pressure generated by the rotation causes the shaft 13 and the sleeve 1 to rotate.
4 is kept in a non-contact state. On the other hand, the relative rotation between the end face of the sleeve 14 and the thrust plate 15 causes the groove 16
Generates a dynamic pressure in the thrust direction. As a result, the sleeve 14 floats from the thrust plate 15 and the sleeve 1
The rotation side member 4, the rotor hub 17, the storage medium 5, and the like rotate at high speed without contacting the whole.

As described above, the dynamic pressure bearing has an advantage that a stable rotation at a high speed can be obtained. However, a problem caused by the high-speed rotation in a non-contact state is that the rotating member is affected by static electricity due to air friction or the like. If it does occur, it will accumulate on the rotating member. In the above-described ball bearing type bearing, static electricity can always be discharged to the fixed member via the ball bearing, so that there is no particular problem. However, the rotating side member in the dynamic pressure bearing is in non-contact with the fixed side member as long as rotation continues, so that the generated static electricity cannot be released to the bearing fixed side member. For this reason, even if static electricity is accumulated, the bearing is not discharged on the bearing side, and the recording medium 5 mounted on the rotating member side and the information recording /
Discharge occurs between the head assembly 21 and the head assembly 21 that performs reproduction, and this discharge may damage the head assembly 21, the storage medium 5, and other HDD devices.

Even in the case of a dynamic pressure gas bearing, when the rotation is stopped, no dynamic pressure is generated, and the rotating side member and the fixed side member constituting the bearing portion come into contact with each other and stop. If it is made of the conductive material described above, static electricity can be released. However, if these members are, for example, non-conductive ceramics, the static electricity cannot be released even if both members come into contact at the time of stop. Even if both members are made of a conductive material, if the rotation operation in a non-contact state is performed continuously for a long time, static electricity is accumulated and the static electricity is discharged on the head assembly side. There is a danger that the HDD equipment may be damaged.

Japanese Patent Application Laid-Open No. H11-55916 discloses means for avoiding the above problem.
A magnetic fluid is filled in a specific portion between the rotating member that relatively rotates in a non-contact state and the fixed member that supports the member, and the two are electrically connected to each other. A technique for discharging static electricity to the fixed member side is disclosed. A magnet is provided at the specific location to prevent the magnetic fluid from scattering.

[0011]

However, Japanese Patent Application Laid-Open No.
The above-described configuration disclosed in Japanese Patent No. 55916 has a problem. First, the place where the magnetic fluid is filled corresponds to a place where air conduction for generating dynamic pressure is required,
The flow of the dynamic pressure generating air penetrates the magnetic fluid layer. For this reason, depending on the dimensions of the bearing portion, the bearing operating conditions, the properties of the sealing member used, and the like, the penetration of the inflowing air breaks the magnetic fluid seal layer, and the magnetic liquid 53
May be scattered.

As another problem, when the peripheral speed of the bearing rotating member sealed by the magnetic fluid is increased to a certain degree or more by rotation, the viscosity of the magnetic fluid filled between the fixed side member and the rotating side member is increased. Resistance is a problem,
As the resistance increases, the torque increases, and as a result, power consumption increases. In addition, the viscous drag can be a source of heat generation, which can result in diminished advantages of using a hydrodynamic gas bearing.

In the case where non-conductive ceramics having high wear resistance and generally used are used for the bearing portion, static electricity accumulated in the rotating member is fixed even when the bearing portion is in contact when the rotation is stopped. It cannot escape to the side member.

The present invention has been made in order to solve the above-described problems. Even in a bearing that performs non-contact rotation, static electricity generated in a rotating member during rotation can be safely escaped to the outside. It is an object of the present invention to provide an HDD which is capable of preventing damage on a head portion side of an HDD and having a countermeasure against static electricity which can be applied to a bearing which cannot be discharged even when stopped due to a bearing member made of a non-conductive material. I have.

[0015]

SUMMARY OF THE INVENTION The present invention solves this problem by positively discharging static electricity generated on the rotating member of the dynamic pressure gas bearing not on the bearing but on the information recording / reproducing side. It specifically includes the following contents.

That is, the present invention described in claim 1 provides:
A spindle motor, a plurality of storage media mounted on the spindle motor and rotating, and a plurality of heads for accessing each information storage surface of the information medium and recording / reproducing information in a non-contact state with the information medium And a hard disk drive comprising:
Discharging static electricity generated on the rotating side member of the spindle motor between a specific one of the plurality of storage media and a specific one of the plurality of head assemblies, the other part of the hard disk drive A hard disk drive characterized by avoiding the occurrence of electric discharge in the hard disk and preventing damage to the hard disk drive equipment due to the electric discharge.

According to a second aspect of the present invention, there is provided the hard disk drive according to the present invention, wherein each of the gaps between the storage surfaces of the plurality of storage media and the plurality of head assemblies which are operating in a non-contact state. A gap between a specific storage medium and the specific head assembly is less than about half of a gap between another storage medium and the other head assembly. By narrowing the gap, a discharge is easily generated in that portion.

According to a third aspect of the present invention, in the hard disk drive according to the present invention, a gap between the specific storage medium and the specific head assembly which is in a non-contact operating state is 15 nm or less. And
By narrowing the gap, a discharge is easily generated in that portion.

The hard disk drive according to the present invention described in claim 4 is characterized in that the conductivity of the specific storage medium is higher (excellent) than the conductivity of other storage media. By increasing the conductivity, a discharge is easily generated in that portion.

According to a fifth aspect of the present invention, in the hard disk drive according to the present invention, the specific head assembly and a carriage supporting the specific head assembly support another head assembly and the other head assembly. It is characterized by being higher than the conductivity of the carriage. By increasing the conductivity, a discharge is easily generated in that portion.

According to a sixth aspect of the present invention, in the hard disk drive according to the present invention, the spindle motor includes a dynamic pressure gas bearing. The effect of the present invention applied to a gas dynamic pressure bearing in which static electricity easily accumulates on the rotating member due to rotation in a non-contact state is particularly remarkable.

According to a seventh aspect of the present invention, there is provided a hard disk drive according to the sixth aspect, wherein at least one of the members constituting the bearing portion of the dynamic pressure bearing according to the sixth aspect is made of ceramics. It is characterized by being formed. When the bearing member is formed of a non-conductive ceramic among ceramics, static electricity is not discharged even if the bearing member comes into contact when the spindle motor is stopped, so that the effect of the application of the present invention is remarkable. Even if the ceramics is conductive, when the spindle motor operates for a long time,
There is an effect of applying the present invention.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an HDD according to the present invention, the relationship between a storage medium and a head assembly for recording / reproducing to / from the storage medium will be described. FIG. 1 shows one of the HDDs described with reference to FIG. 3 in which one storage medium 5 and one head assembly 21 are taken out, and the relationship between the two is viewed in a plane parallel to the rotation plane of the storage medium 5. It is. In this drawing, in a state where the storage medium 5 is stopped (that is, the spindle motor is stopped), at this time, the head assembly 21 is moved by the urging force shown by the arrow 26 in the direction of the arrow 26 applied by the carriage 25. 5 comes into contact with the surface and stops.

Here, what constitutes the head assembly 21 is a slider 22 which is in contact with the storage medium 5.
A head core 23 fixed to the slider 22 for recording / reproducing information on the surface of the storage medium 5, and a micro positioner 2 for finely adjusting the direction of the slider 22.
4, which are attached to a gimbal (not shown) which is at the tip of the carriage 25 and maintains the horizontal position.

Although the slider 22 has a substantially rectangular parallelepiped shape, an inclined portion is provided at one end on the side in contact with the storage medium 5 indicated by reference numeral 27 in a direction away from the contact surface of the storage medium 5. Have been. Incidentally, reference numeral 21 ′ indicated by a dotted line in the figure indicates another head assembly that is in contact with the surface of the storage medium 5 opposite to the surface facing the head assembly 21, and the storage medium 5 is usually provided on both sides. Since it has an information storage surface, recording and reproduction are performed by the head assemblies 21 arranged on both sides.

FIG. 2 shows an operation in which the spindle motor on which the storage medium 5 is mounted rotates between the storage medium 5 and the head assembly 21 having the above-described relationship, and information is recorded / reproduced therebetween. The state is shown. Due to the rotation of the spindle motor, the storage medium 5 moves at a high speed in the direction indicated by the arrow 31 in the figure. At this time, the gas near the surface of the storage medium 5 (air in the case of operation in the atmosphere) has its viscosity. As shown by an arrow 32, the slider 22 is caught between the inclined portion 27 of the slider 22 and the storage medium 5. As a result of the dynamic pressure due to the wedge effect of the fluid entrainment, the slider 22
6, and the storage medium 5 and the head assembly 21 are in a non-contact state. The head assembly 21 records and reproduces information from and to the information storage surface of the storage medium 5 by the head core 23 in the non-contact state.

Here, the flying height of the slider 22 from the storage medium 5 shown by h in the drawing tends to decrease with the recent increase in the density of the storage medium, but at present, it is about 30 to 60 nm. It is. This is a gap much smaller than a few μm even if the gap between the dynamic pressure bearings of the spindle motor is narrow. Therefore, when static electricity is accumulated on the rotating member of the spindle motor described above,
The possibility of electric discharge between the slider 22 and the storage medium 5 is extremely high, and if electric discharge occurs, there is a concern that the head assembly may be destroyed.

The HDD according to the present invention provides a specific storage medium (hereinafter, referred to as a storage medium) having a further increased possibility of occurrence of discharge between the storage medium and the head assembly which have a high possibility of discharge as described above. , A dummy disk) and a specific head assembly (hereinafter, referred to as a dummy head), and a discharge is intentionally caused at the specific portion. When static electricity is accumulated in the rotating member of the motor, a discharge is induced between the dummy disk and the dummy head, thereby avoiding a discharge in other regular heads and protecting the entire HDD.

As shown schematically in FIG. 4, a spindle motor usually used for an HDD is equipped with several to ten or more storage media when the number is large. In the present embodiment, one of the dummy disks is used as a dummy disk dedicated to discharge, and conditions for easily generating a discharge are set between the dummy disk and a dummy head facing the dummy disk. One specific measure is to make the flying height of the dummy head from the dummy disk extremely narrower than the flying height of other regular head assemblies. This can be easily implemented by making the slider urging force 26 for urging the dummy head toward the dummy disk larger than that of other head portions. In the present embodiment, the flying height h of the dummy head is less than half the other flying height. More preferably, the flying height h of the dummy head from the dummy disk is 15 nm or less.

As a further means for positively discharging between the dummy disk and the dummy head, a material having better conductivity than the material of the ordinary storage medium 5 and the head assembly 21 may be used. Shall consist of For example, if the surface of the regular storage medium 5 is an aluminum deposited layer, the surface of the dummy disk is a copper deposited layer. If the regular slider 22 is made of stainless steel, the dummy head is silver plated. In addition, if the regular carriage 25 is made of stainless steel, an alternative material may be used, such as that the carriage supporting the dummy head is made of copper. By keeping the electric resistance of the dummy disk / dummy head as a whole smaller than that of other regular ones, discharge can be induced in the path of the dummy disk / dummy head.

Although the HDD having the countermeasures against static electricity according to the present invention has been described above, the present invention is applied to an HDD having a dynamic pressure gas bearing in which static electricity is accumulated in a rotating member.
D is particularly advantageous, but not limited thereto. For example, even in the case of a bearing having a ball bearing, if the member on which the ball bearing is mounted is a non-conductive material or a material having a high electrical resistance, static electricity escapes via the ball bearing. However, discharge may occur in the head assembly.
Even in such a case, by applying the present invention, it is possible to avoid damage to HDD equipment due to discharge.

[0032]

According to the present invention, even when static electricity is generated on the rotating member of the spindle motor, the discharge is generated between the dummy disk and the dummy head according to the present invention. In this case, the occurrence of discharge is avoided, damage to the regular head assembly can be prevented, and a highly reliable HDD can be obtained.

When a non-conductive material such as a non-conductive ceramic is used as a bearing member of the dynamic pressure gas bearing,
Even when the bearing members come into contact with each other at the time of stoppage, no discharge occurs, and therefore, the static electricity is sequentially accumulated in the rotating side member. In this case, the occurrence of electric discharge in the regular head assembly can be avoided, and damage to the head portion can be prevented.

[Brief description of the drawings]

FIG. 1 is a partial side view showing a head portion of an HDD.

FIG. 2 is a side view showing an operation state of a head unit shown in FIG.

FIG. 3 is a perspective view showing an overall outline of an HDD.

FIG. 4 is a cross-sectional view of a spindle motor provided with a ball bearing according to the related art.

FIG. 5 is a cross-sectional view of a spindle motor provided with a dynamic pressure gas bearing according to the related art.

[Explanation of symbols]

1. 4. Spindle motor, 10. storage media,
9. Spindle motor, Disc part, 20. Head part, 21. Head assembly, 25. carriage.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kaoru Murabe 1-1-1 Kunyokita, Itami-shi, Hyogo F-term in Sumitomo Electric Industries, Ltd. Itami Works (reference) 5D091 AA08 FF20 HH15

Claims (7)

[Claims] 1. A spindle motor, a plurality of storage media mounted on the spindle motor and rotating, and recording / reproduction of information in a non-contact state with the information medium by accessing an information storage surface of each of the storage media. A plurality of head assemblies for performing a static electricity discharge between a specific one of the plurality of storage media and a specific one of the plurality of head assemblies; A hard disk drive characterized in that the electrostatic discharge is prevented from being generated in other parts of the hard disk drive and the hard disk drive equipment is not damaged by the discharge. 2. A gap between the specific storage medium and the specific head assembly in each gap between the storage surfaces of the plurality of storage media and the plurality of head assemblies that are operating in a non-contact state. 2. The hard disk drive according to claim 1, wherein a gap of the hard disk drive is about half or less of a gap between another storage medium and a head assembly facing the storage medium. 3. The method according to claim 1, wherein a gap between the specific storage medium and the specific head assembly in a non-contact operating state is 15 nm or less.
Hard disk drive as described in. 4. The method according to claim 1, wherein the conductivity of the specific storage medium is higher than the conductivity of another storage medium.
The hard disk drive according to claim 1. 5. The electrical conductivity of the specific head assembly and the carriage supporting the specific head assembly is higher than the electrical conductivity of the other head assembly and the carriage supporting the other head assembly. The hard disk drive according to any one of claims 1 to 4. 6. The hard disk drive according to claim 1, wherein the spindle motor includes a dynamic pressure gas bearing. 7. The hard disk drive according to claim 6, wherein one or more members constituting a bearing portion of the dynamic pressure bearing are formed of ceramics.