Dynamic magnetic information storage or retrieval – Head mounting – For moving head into/out of transducing position
Reexamination Certificate
1999-02-11
2001-09-18
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head into/out of transducing position
C360S255000
Reexamination Certificate
active
06292333
ABSTRACT:
BACKGROUND OF THE INVENTION
In general, this invention relates to hard disk drive technology; more particularly, it relates to a drive having an inner diameter (“I.D.”) ramp loading system that employs multiple-function spacer structure.
An important issue that arises in designing a hard disk drive relates to head parking which involves placing a head stack assembly in an appropriate position while there is no power applied to the drive. Generally, some type of head parking is needed to avoid problems that result if a spinup operation is initiated while a head contacts any part of a disk surface that defines a data recording zone. In accordance with some designs, each recording surface has a landing zone at which the head for that recording surface is parked. In accordance with other designs, a ramp loading system is provided. Some ramp loading systems are categorized as outer diameter (“O.D.”) systems and others as I.D. systems. With either an O.D. system or an I.D. system, the head-position control system that controls the angular position of the head stack assembly performs a parking operation to unload the heads before completion of spindown, and performs a loading operation immediately after at least substantial completion of spinup. With an O.D. system, the unloading occurs adjacent the O.D. With an I.D. system, the unloading occurs adjacent the I.D. and can involve multiple phases including a seek phase at full spin rate followed by an unloading phase starting at a reduced spin rate and completed when the spin motor stops spinning.
For additional background regarding prior art I.D. ramp loading systems, see U.S. Pat. No. 5,644,451 to Chan et al., U.S. Pat. No. 5,574,604 to Berg et al., and U.S. Pat. No. 5,701,219 to Shafe.
The teachings of the prior art regarding I.D. ramp loading systems leave unresolved various significant technical difficulties with respect to designing a practical system for a high capacity, high performance, high rpm disk drive. In such a drive employing multiple disks in a disk stack, a tight three-way merge tolerance is demanded not only between the disk stack and the head stack, but also between the head stack and the ramp stack, as well as the ramp stack and the disk stack. The z-height variance of a ramp stack itself has to be minimized, while all the ramps have to be precisely machined to a sophisticated ramp profile, made from a thermally stable and wear resistant materials. The disk flutter at OD is a function of spin rate; thus, higher rpm drives have greater such disk flutter; this further stresses a tight head/disk merge for any OD load/unload system. This, coupled with dramatically increasing linear velocity at OD poses severe risk for loading/unloading a head onto a disk. In addition, a given range of the disk surface at OD has to be allocated to loading/unloading, which becomes a significant loss to the premium real estate for data recording.
Other technical difficulties arise in I.D. ramp loading systems designed in accordance with the prior art such as the teachings of the patents referred to above. There exists a significant need to overcoming such difficulties with a low cost approach appropriate for mass production of cost competitive drives. Lastly, it has not proven practical to add effective shrouding around the O.D. of the disk pack, and shrouding is critically important to minimizing motor power consumption, air turbulence and disk flutter in high performance disk drives with an extremely high track following requirement.
SUMMARY OF THE INVENTION
This invention can be regarded as a disk drive having ramp-loading means. The drive comprises a disk having a disk spin axis and recording surface for storing data; a head for reading data from the recording surface; a spindle motor having a rotor; and clamping means for clamping the disk so that the disk spins with the rotor.
Significantly, the drive includes a multiple-function spacer means forming part of the clamping means and forming part of the ramp-loading means. The ramp-loading means includes a lift tab having protuberance projecting away from the lift tab toward the recording surface such that the protuberance defines a protuberance depth. The spacer means has a spacer spin axis and an axially-symmetrical surface. The spacer spin axis is aligned with the disk spin axis and the axially-symmetrical surface faces away from the recording surface. The axially-symmetrical surface defines, in radial cross section, a sloped section and a recessed section adjoining the sloped section, the recessed section defining a recess depth, the recess depth not exceeding the protuberance depth. The drive also includes head-position control means for controlling a parking operation carried out while the disk and the spacer means are spinning and in which the protuberance rises adjacent the sloped section and comes to rest in the recessed section. In one embodiment, the spacer means comprises an integral structure having parallel spaced-apart surfaces that are under compression within the clamping means. In another embodiment, the spacer means comprises multi-piece structure compressed between a pair of disks, the multi-piece structure including a ring having bearing surfaces and a pair of elements having facing contoured surfaces.
An embodiment of the invention can eliminate the three-way Z-height calibration required for an OD load/unload ramp and the disk array. With head loading/unloading being performed at inner circular rings of the disk surface, less premium for data recording and reserved as the loading/unloading buffer zone but normally occupied by the landing zone texture. Preferably, head load/unload lifters, made as part of the whole head suspension pieces, all have a contoured tip, specially designed and coated with wear resistant hard coating. The heads are unloaded from the disk surfaces while those half spherical tips slide onto the outer edge ramps of disk spacers, and then are latched into the recesses behind the ramps. The heads are loaded onto the disk surfaces while the actuator arm drives the half spherical tips outwards from the recesses, down along the ramps approaching the disk surfaces, keeping rotating both the disks and their spacers. The spacer ramp profiles will self adjust in Z-height to the disk array which then needs only one, not three, Z-height merge adjustment with the head stack. The clearance and tolerance requirement between a ramp and disk surface with an OD ramp drive system is then removed, allowing smaller disk spacing and tighter Z-height control, since the ramp here is attached to the disk surface at ID. The circular load/unload spacers with ramps can be machined from more thermally and mechanically stable materials like aluminum or stainless steel, and then coated with a hard, wearing resisting coating such as diamond like carbon, and then lubricant. If necessary, aluminum or stainless steel is electrically plated with Ni—P coating and polished before being further coated with wear resistant coating. The rotating spacer ramps underneath the lifting contoured tips help create an air bearing force which pushes up the sliding protuberances away from the spacer ramps and therefore, reduces the interference. If any contact does occur, wear can be minimized with the wear resistant hard coatings on both the spacer ramps and the half spherical tips.
REFERENCES:
patent: 5574604 (1996-11-01), Berg et al.
patent: 5585980 (1996-12-01), Boutaghou
patent: 5625514 (1997-04-01), Kubo et al.
patent: 5644451 (1997-07-01), Chan et al.
patent: 5701219 (1997-12-01), Shafe′
patent: 6181529 (2001-01-01), Aoyagi et al.
Blumentritt Bruce F.
Huang He
Xue Sidney Y.
Kim Won Tae C
Shara Milad G
Tupper Robert S.
Western Digital Technologies Inc.
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