LOW PROFILE HEAD DISK ASSEMBLY

Abstract: An improved low profile magnetic head disk assembly (28) is used with dynamic magnetic information storage devices or rigid disk drives. The HDA (28) includes a head mounted to a suspension, wherein the suspension base plate is an integral part of the actuator arm (34). Each actuator arm (34) is in close registration with a bearing (36). The actuator assembly positions the head in close proximity with the rigid disk (42) surfaces, with the actuator arms (34) positioned exterior to the disks (42) and not passing over the surface of the disks (42). The actuator arms (34) may be a single piece for each disk (42), two pieces (one for each suspension), or three pieces (two actuator arms and one spacer). The center line of the actuator(s), with or without the spacer, is at the center line of the disk, thus reducing the total HDA (28) height.

Description: LOW PROFILE HEAD DISK ASSEMBLY Field of the Invention This present invention pertains to an improved magnetic head disk assembly (HDA) for use with dynamic magnetic storage devices or rigid disk drives. More specifically, the present invention provides a low profile magnetic head disk assembly (HDA) that decreases the total height of the HDA and disk drive and improves manufacturabilit . Background of the Invention Currently, the storage industry is experiencing a need for very small low capacity single disk drives that can be manufactured and sold at low cost. Applications for such devices would be in the areas requiring very small packages such as notebook personal computers. Accordingly, there is a need for a low cost, low height HDA for small single disk drives. Conventionally, suspension base plates are welded to one end of suspension load beams and the base plates are used to attach the suspensions to the actuator arms. These suspensions are positioned vertically between their actuator arm and the respective disk surface such that the height of the HDA is significantly high. The present invention uses a load beam welded to the actuator arm so that the same structure is then acting both as the actuator and the suspension base plate such that the actuator arm is in the same plane as the disk and the suspension is not positioned between the actuator arm and a disk. Therefore, the overall height of the head disk assembly (HDA) is reduced. For a single disk application, the space savings is approximately 1.27 mm (0.050") or about 37% of the total disk stack height. Some prior art configurations have incorporated a load beam welded to an actuator arm in very large disk drives to reduce the space requirements. In those devices, however, the arm passed over the disk and the actuator arms were not directly positioned around a bearing. Instead, these prior art actuator arms were registered to a separate positioner that was in contact with the bearing. Further, prior art actuators for large disk drives that extend over disks have high inertia, which is undesirable. According to an embodiment of the present invention, the arms do not pass over the disk, they facilitate the use of the suspension in very small disk drives, and they are closely coupled to the bearing assembly. The present invention also provides an embodiment in which the actuator arms pass over the disk but where the inertia is kept low by providing a construction where the arms are very thin and short (suitable for small disk drives) . The prior art suspensions heretofore incorporated actuator arm assemblies for large disk drives having several complicated pieces and spacers, while the present invention utilizes an easy to manufacture arm and spacer suitable for small disk drives. Brief Description of the Invention A low profile rigid disk drive assembly or magnetic head disk drive assembly comprises: a. a rigid disk; b. two actuator plates stacked back to back, such that a center line between them is coplanar with a disk center line, the actuator plates are unable to pass over the disk, and the actuator plates are rotatable about an axis common to the plates; c. a bearing rotatable about the common axis and fixing the actuator plates to the disk drive; d. two load beams, one attached to each actuator plate on opposite sides thereof, such that the load beams form an outermost portion of a head stack assembly; e. a gimbal forming a part of or attached to each load beam; and f. a read write head attached to each gimbal for operationally interacting with the surface of the disk. The basic element of one embodiment of the low profile HDA provided by this invention is the use of a stampable actuator plate that is welded to a single load beam to form a single assembly. Two or more of these assemblies are pressed onto a bearing, thus eliminating the E-Block actuator of conventional HDAs. In addition to achieving a major cost reduction, the overall stack height for the HDA according to this invention may be' reduced by 35% over that of a conventional HDA. It is an object of the present invention to provide an improved head disk assembly having a unitary actuator and suspension base plate structure. It is another object of the present invention to provide a head stack or head disk assembly having reduced vertical spacing of the disks A further object of the present invention is to offer a head disk assembly that is easy and inexpensive to manufacture and assemble with a reduced number of components. These and other objects of the present invention will be apparent with reference to the drawings, the description of the preferred embodiment and the claims. Brief Description of the Drawings Fig. 1 is perspective view of a prior art head disk drive assembly; Fig. 2 is a profile view of the prior art head disk drive assembly of Figure 1; Fig. 3 is a perspective view of an embodiment of the present invention in which the actuator plates do not pass over the disk; Fig. 4 is a profile view of the embodiment of Figure 3 with multiple disks; Fig. 5 is a profile view of the embodiment of Figure 3 with a single disk; Fig. 6 is a perspective view of an embodiment of the present invention in which the actuator plates pass over the disk, but are relatively thin and short and are positioned between the load beams and disk; Fig. 7 is a profile view of the embodiment of Figure 6 with multiple disks; Fig. 8 is a profile view of the embodiment of Figure 6 with a single disk; and Fig. 9 is a perspective view of an additional embodiment of the invention. Detailed Description of the Invention The head disk drive assembly of the present invention overcomes the limitations of the prior art . by making the base plate and the actuator as a single unitary piece. In doing so, the manufacture of the head disk assembly components is greatly simplified, while the overall height of the assembly is reduced. More specifically, the head disk assembly of the present invention includes a head mounted to a suspension wherein the suspension base plate is an integral part of the actuator arm. Each actuator arm is placed in close registration with a bearing conventional in the art and is pressed or glued in position or fixed with a similar process. The actuator assembly positions the heads or sliders mounted at the ends of the load beams for controlled tracking over the rigid disk surfaces with the actuator arms not passing over the disks. The actuator arms may be provided in a single piece embodiment for each disk, two pieces (one for each suspension), or three pieces (two actuator arms and one spacer). The center line of the actuator(s), with or without the spacer, is in the same plane as the disk, such that the total height of the head disk assembly is reduced. Referring now to the drawings, Figures 1 and 2 show a prior art swage technology head disk drive assembly 10 with an E-Block type actuator 12. E-Block 12 is typically cast or extruded and then the suspension contact area 14 of the projecting arms thereof is machined flat. Next, swage holes 16 are drilled, reamed or electrical discharge machined. Finally, head suspension assemblies (HSA) 18 are swaged to actuator arms 20. Notice that the ends of actuator arms 20 are between disks 26 such that each HSA 18 is sandwiched between its respective contact area 14 and the disk. This, along with the swage technology, limits the ability to reduce HDA height. Figures 3, 4 and 5 illustrate one embodiment of a low profile HDA 28 of the present invention, with multiple 30 and single disk configurations 32 shown in Figures 4 and 5 respectively. Note that the single piece, machined E-Block has been eliminated and replaced with individual stacked actuator plates 34 positioned around conventional bearing 36. Plates 34 may be attached to bearing 36 using a number of different processes. For example a suitable adhesive may be used to secure the plates to the bearing or one of a number of interference fit techniques may be used. Interference fit by use of thermal shrink techniques which may be combined with press fit techniqus may all be used. Load beams 38 are directly attached, for example by welding, to actuator plates 34. In this embodiment the actuator plates are configured to remain exterior to the disks by not passing over the surface of the disk and thereby permit substantial reductions in the height of the HDA. Therefore, use of the structure shown in Figs. 3-5 allows the following processes to be eliminated: * extrusion or casting of a complex E-Block and its unitary actuator arm structure. * machining of surfaces which are to be swage connected to load beams. In the present invention the actator arms can be stamped and no special machining is neccessary preparatory to the forming of the weld connection. * drilling and reaming of holes for swage connection which are unneeded for connections using the direct weld or clamped embodiments of the present invention. * swaging. Because the relatively thinner load beams 38 are the outermost portion of the entire HDA stack 28 and have reverse rails 40 which extend in the direction of the surface of the disk rather than increasing the height of the slider and load beam assembly, the total HDA height may be substantially reduced, using the teachings of the present invention, over that possible with the prior art. Further, using the present invention, the spacing between disks 42 may be substantially lower than spacing achievable using prior art techniques and compares to the spacing achieved with the interlocking swage head suspension connection technology disclosed in commonly assigned patent application SN 542,423, filed June 22, 1990, entitled Head Suspension Connection Assembly. Figures 6, 7 and 8 illustrate a second embodiment of the low profile HDA 44 of the present invention, with multiple 46, and single disk configurations 48, shown in Figures 7 and 8, respectively. In these embodiments, actuator plates 50 pass over disk 52 surfaces, but they are between load beams 54 and disks 52. Thus, the total HDA height of the second embodiment 44 is the same as that of the first embodiment 28. The second embodiment 44 has more inertia than the first embodiment 28, but offers the ability to use shorter load beams 54. Shorter load beams 54 may typically demonstrate improved resonance performance. This multiple disk configuration 46 has four actuator plates 50 and three spacers 56, while the single disk configuration 48 has two actuator plates 50 and one spacer 56. Figure 9 illustrates a third embodiment for a low profile HDA in accordance with the present invention. In this embodiment, the actuator plate 62 has an opening 64 which can be positioned around a separate cylindrical bearing piece 66 and secured by releasing tabs 68 and 70 to spring back to create an interference fit between spring 64 and bearing 66. The unitary actuator plate has upper 76 and lower 78 load beams mounted adjacent to its upper and lower surfaces respectively. In the embodiment shown, the load beams are secured to the actuator arm using resilient retaining clips 80 and 82 as disclosed in commonly assigned application SN 7-612012, filed November 9, 1990, which is incorporated herein by reference, such clip structures may be unitary with the load beams 76 and 78 or separate structures. This embodiment is relatively simple to construct since it does not require the use of the complex E-block structure and the connection of load beams 76 and 78 to the actuator arm is easily accomplished but allows for removal and recoπnection in the event that repairing or rebuilding of the assembly becomes necessary.

Claims: What Is Claimed Is: 1. A rigid disk drive assembly comprising: a rigid disk; two actuator plates stacked back to back, such that a center line between them is coplanar with a disk center line, said, actuator plates rotatable about an axis common to said plates without extending over the surface of the disk; a bearing rotatable about said common axis and fixing said actuator plates to a disk drive; two load beams, one attached to each actuator plate on opposite sides thereof, such that load beams form outermost portions of a head stack assembly; gimbal means associated with each load beam; and read write head means mounted on each gimbal means for operative interaction with the surface of the disk. 2. The disk drive assembly according to claim 1, wherein said load beams are welded to said actuator plates. 3. The disk drive assembly according to claim 1, wherein said actuator plates are formed by stamping or a similar process. 4. The disk drive assembly according to claim 3, wherein said load beams are bonded to said actuator plate. 5. The disk drive assembly according to claim 3, wherein said load beams are swaged to said actuator plate. 6. The disk drive assembly according to claim * 3, wherein said load beams are attached to said actuator plate by an interference fit. 7. The disk drive assembly according to claim 6, wherein said interference fit is an Interlock interference fit. 8. A rigid disk drive assembly comprising: a rigid disk; an actuator plate having a center line coplanar with a disk center line, said actuator plate rotatable about an axis without extending over the surface of said disk; a bearing rotatable about said common axis and fixing said actuator plate to a disk drive; two load beams attached to said actuator plate on opposite sides thereof, such that said load beams form outermost portions of a head stack assembly; gimbal means associated with each load beam; and a read write head mounted on each gimbal means for operative interaction with the surface of the disk. 9. The disk drive assembly according to claim 8, wherein said load beams are welded to said actuator plate. 10. The disk drive assembly according to claim 8, wherein said load beams are attached to said actuator plate using a clip. 11. A low profile magnetic head disk drive assembly for a magnetic information storage device comprising: (a) a rigid disk; (b) two actuator plates stacked back to back above and below the plane of the disk, said actuator plates rotatable about an axis common to said plates and parallel to the axis of rotation of the disk; (c) a bearing rotatable about the actuator plate axis and fixing said actuator plates to a disk drive housing; (d) two load beams, one of which is attached to each actuator plate, such that the load beams form outermost portions of a head stack or actuator assembly; (e) gimbal means associated with each load beam; and (f) magnetic read write head means mounted on each gimbal means for operative interaction with the surface of the disk. 12. The head disk assembly according to claim 11, wherein said actuator plates are spaced apart with spacers fixed to said bearing and rotatable about said actuator plate axis. 13. The head disk assembly according to claim 11, wherein said load beams are welded to said actuator plates. 14. The head disk assembly according to claim 11, wherein said actuator plates are formed via stamping or a similar process. 15. The head disk assembly according to claim 11, wherein said load beams are attached to each actuator plate such that the center plane for each pair of actuator plates is coplanar with their respective disk. 16. The head disk assembly according to claim 11, wherein said load beams are bonded to said actuator plates. 17. The head disk assembly according to claim 11, wherein said load beams are attached to said actuator plates via an interference fit, such as pressing, clipping or swaging. 18. A low profile magnetic head disk drive assembly for a magnetic information storage device comprising: (a) a plurality of rigid disks; (b) two actuator plates stacked back t- back with each disk, such that a center line between said actuator plates is coplanar with a center line of said disks, and said actuator plates rotatable about an axis common to said plates; (c) a bearing rotatable about said common axis and fixing said actuator plates to a disk drive housing; (d) two load beams, one each of which is attached to each actuator plate, such that load beams form outermost portions of a head stack or actuator assembly; (e) gimbal means associated with each load beam; and (f) magnetic read write head means mounted on each gimbal means for operative interaction with the surface of the disk. 19. The head disk assembly according to claim 18, wherein said actuator plates are spaced apart with spacers fixed to said bearing and rotatable about said common axis. 20. The head disk assembly according to claim 18, wherein said load beams are welded to said actuator plates. 21. The head disk assembly according to claim 18, wherein said actuator plates are formed via stamping or a similar process. 22. The head disk assembly according to claim 18, wherein said load beams are attached to each actuator plate, such that the center line for each pair of actuator plates is coplanar with the center line of their respective disk. 23. The head disk assembly according to claim 18, wherein said load beams are bonded to said actuator plates. 24. The head disk assembly according to claim 18, wherein said load beams are attached to said actuator plates via an interference fit, such as pressing, clipping or swaging. 25. The head disk assembly of claims 1, 8, 11, or 18 wherein the actuator plates are attached to the bearing. 26. The head disk assembly of claim 25 wherein the actator plates are attached to the bearing fay an interference fit. 27. The head disk assembly of claim 26 wherein the interference fit is a press fit. 28. The head disk assembly of claim 26 wherein the interference fit is a thermal shrinkage fit. 29. The head disk assembly of claim 26 wherein the interference fit is provided by means of a retaining ring. 30. The head disk assembly of claim 25 wherein the actuator plates are attached to the bearing by means of adhesive.

Inventors: JURGENSON RYAN A, JURGENSON, RYAN, A.
Applicants: HUTCHINSON TECHNOLOGY, HUTCHINSON TECHNOLOGY INCORPORATED
Application year: 1992
Main classification: G11B5
IPC codes: G11B5, G11B21