A DISK ENCLOSURE

Abstract: An enclosure for a rigid disk data file is shown which includes a base casting (6) and a cover (24) that interface along a planar surface that is not perpendicular to the axis of the spindle supporting the data disks (8). The base casting (6) at one side extends axially along the disk stack and has the transducer positioning actuators mounted through openings therein. At the opposite side, the disk stack is fully exposed to permit easy access to the disk surface for procedures such as servo writing during manufacture of the drive. This structure makes possible concurrent operation of the product heads and servo writing heads.

Description: The present invention relates to disk storage device. In particular, it is directed to a storage device head-disk enclosure for drives that are servo written with permanent data. Disk enclosures must be sealed against particulate matter that might be introduced from the surrounding ambient atmosphere. A conventional disk enclosure is described in IBM Technical Disclosure Bulletin, Vol. 25, No. 7A, December 1982, pp. 3238-9. This document discloses a hard-disk enclosure including a base that comprises a wall section surrounding the disks and a housing for receiving an activator carrying transducer heads, and a cover member which cooperates with the base to enclose and seal the disks. Therefore, the head-disk enclosure is hermetically sealed, sealed with the provision of a breather filter or provided with a continuous supply of filtered air. Rigid disk files also have permanently recorded servo information that must be written on the disk storage surfaces at manufacture. The disk stack of the drive should be accessible from a radial side to enable the servo writing operation to occur without having equipment that might be the source of particulate matter, suspended over the disk data surfaces. A significant portion of the disk stack periphery should be exposed to enable several transducer heads to simultaneously access the disk surfaces, since some servo read-write functions must occur concurrently. Further, the operations that could be accomplished separately or consecutively, would still be accomplished on the most cost effective basis if done simultaneously. Also, the product heads that will be permanently associated with the disk file should be mounted and operable during the servo write operation. This permits the servo written information to be placed on the data surface with the same departure from radial transducer positioning and transducer skew as the individual transducer head that will function with the particular surface during the life of the product. Summary of the Invention In the head disk enclosure assembly of the present invention as defined in claim 1, the cover and base cooperate to present a planar interface surface which is inclined at an angle and not perpendicular to the axis of the disk stack. The base casting includes an upright portion through which is mounted the product actuator. The product heads carried by this actuator can be used to write selected tracks and the servo heads can be positioned to write with the same deviations. Thus the precision writing of the servo heads can be tailored to have the same non-radial and skew characteristics as the less costly product heads. This servo writing technique is described in U.S.-A 4,371,902. Use of the diagonal cover structure makes possible concurrent operation of product heads and the various heads necessary to perform the servo write operations with the cover removed in a clean room environment. It is also possible to use multiple heads in addition to the servo write heads for functions such as erase, the provision of a clock track and speed determination and regulation. This can be accomplished without mounting heads above the disk assembly where they are prone to cause particulate contaminants to be deposited on the disk data surfaces. The interface surface between the base casting and the cover member is a continuous closed coplanar surface surrounding and enclosing the disk stack. This makes it easier to effect a permanent high integrity seal between base and cover. The base casting includes flange portions at the margins of the interface surface which position and align the gasket and the cover. Brief Description of the Drawing Fig 1 is an exploded, perspective view of a disk drive with the base casting and cover of the present invention with partially assembled actuators, the disk assembly and the filter cartridge. Fig 2 is a perspective view of the base casting and disk assembly from the radial side opposite the wall portion through which the actuators are mounted. Fig 3 is a plan view of the gasket. Fig 4 is a perspective view of the disk drive with the cover and actuators assembled to the base member. Fig 5 is an exploded perspective view illustrating the mounting of the actuators to the base member. As seen in Figs 1 and 2 the head-disk enclosure includes a base 6 which has, a spindle (48) and a wall portion 7 that extends vertically along one radial side of the space occupied by the disk assembly 8 and at the opposite radial side exposes the edge of the lowest disk of the mounted disk assembly as the parting line or surface between disk pack and cover extends below the plane of the base surface 9 that confronts the lowermost disk surface. The side wall 7 has two apertures 11, 12 in the upright mounting flange portions 13 through which the product actuators 15, 16 carried by the drive are mounted. The upright flange portion 13 is of increased thickness and adjoins support structures 17, 18 that provide rigidity and partially define the cylindrical volume of the enclosure about the rotating disk assembly 8. The casting presents a continuous planar surface 20 which surrounds disk assembly 8 and is inclined to the disk assembly spindle axis. The gasket 21 of Fig 3 is received and supported on surface 20. The cover 24 presents a lower edge surface 25 that is planar and is compressively retained against gasket 21 by a series of three spring clips 28. The cover 24 includes a series of latch structures 30 that cooperate with the spring clips 28 and include rigid downwardly depending tabs 31 that cooperate with the base casting to provide alignment between base 6 and cover 24. In the assembled condition, the latch rigid depending tab 31 is received in the base casting groove along the surface 34 and is confined by the end surfaces 35. Each spring clip 28 has a pair of flexible hook portions 37 that engage the margin of the base casting and a central tab 38 that is received by and retained by the latch central hook portion 40. With the hook portions 37 engaging the base 6 and the central tab 38 engaging the latch central hook portion 40, the upper part 41 of the spring clip can be flexed to an over center position to secure cover and base together. In the latched position, the upper margin 42 of the spring clip is retained under the turned upper marginal portion 43 of latch 30. The base casting 6 also presents confronting surfaces 45 along the edges of the planar surface area 20 on which the gasket 21 is supported to confine and align the cover 24. The cover engages gasket 21 between the vertical portion 7 and the confronting surface 45 (Fig 1) of support structure 17 and within the inclined surfaces 46, 47. The disk drive as illustrated includes four disks clamped together as an assembly 8 and to the spindle 48 by a clamping ring 50 (Fig 2). The upper clamp element 51 has interior apertures 52 and apertures 53 along the line of contact with the upper disk surface and each of the spacers (not shown) between adjoining disks are apertured to enable air entering axially downward along the spindle to be expelled radially along each of the disk surfaces. A hub cap 55 with depending vanes 56 is secured to the spindle by a clip 57. The disk and spindle assembly is rotated in unison by a motor (not shown) which is attached to the spindle shaft and recessed in the base casting exterior to the space defined by the casting and the cover. The spindle shaft extends through base casting 6, being supported in bearings mounted in a bearing tower affixed to or formed in the base casting. Also secured to the inner surface of the cover 24 is a filter cartridge assembly 60 including a recirculating filter media 61 and a breather filter media 62. The cartridge is retained by a filter clip 63 that engages a boss 64 on the cartridge that extends through the cover aperture 65. The breather filter media 62 filters air entering through the cover apertures 66 with passage through the media assured by the gasket 67 positioned between cartridge 60 and cover 24. The actuators 15, 16 are mounted on the base casting 6 with the voice coil motor section 69 projecting outward and the transducer carriage assembly 70 (Fig 5) projecting through the apertures 11, 12 respectively at which the actuator is mounted. As shown in Fig 5, each actuator is secured to the base casting by four mounting screws 72 with air tight integrity maintained by a pair of shims 73 and an actuator seal 74. In this figure, the inwardly projecting transducer assembly 70 with the associated flexure mountings, sliders, gimbeling and load beams is also visible. It will be noted that the actuator assemblies 15, 16 are mounted on casting 6 in vertically offset positions to permit actuator 16 to access the upper two disks and actuator 15 to access the lower two disks. Fig 4 shows the disk drive in the assembled condition with actuators 15, 16 attached and the cover 24 retained on the base casting 6 by the spring clips 28 in the secured position. The electronics within the enclosure defined by the base and cover assembly are connected to the exterior by the flexible flat cables 76 which connect to the voice coil motor of the actuator and the actuator cables 77 which connect to the arm electronics or directly to the transducers to read and write data from or to the disk surfaces. When the drive is assembled with the disk assembly 8, drive motor, and actuators 15, 16 mounted on base casting 6, but with the cover 24 removed in a clean room assembly environment, the disk assembly may be rotated and the product actuators 15, 16 utilized during the servo writing of the permanent data on the disk surfaces. The accessibility of the disks at the side radially opposite the product actuators, makes it possible for multiple transducer heads to simultaneously access the disk surfaces without the necessity of suspending the head mounting structures over the disk stack where they might be prone to allow debris to fall on the disk data surface during servo writing operations. The servo writing procedure often requires the use of clock and speed heads in addition to the multiple servo heads positioned at each of the data surfaces.

Claims: A head disk enclosure assembly for a rigid disk drive which includes a plurality of disks (8) mounted on a spindle (48) for rotation in unison about the axis of the spindle (48) said assembly including : a base (6) on which said spindle (48) is mounted for rotation about said spindle axis; a cover member (24) that cooperates with said base (6) along a continuous closed planar interface surface (20) to enclose said plurality of disk (8); said base includes a wall portion (7) extending axially along one side of of said disks (8) and partially surrounding said disks (8) and said wall portion (7) presents means (13) for mounting an actuator carrying transducer heads (70); said assembly being characterized in that : said planar interface (20) is nonperpendicular with respect to said spindle axis and surrounds said spindle axis whereby radial access to said disks (8) diametrically opposite said actuator mounting means (13) is unobstructed when said cover member (24) is removed; and, securing means (30,28) are provided for attaching said cover member (24) to said base (6). The head-disk enclosure assembly of claim 1 further comprising gasket means (21) that extends in a continuous closed configuration along said planar interface surface (20) between said base (6) and said cover (24) and is compressively retained therebetween. The head-disk enclosure assembly of claim 1 or 2 wherein said base (6) comprises a casting (13,17,18) which at said one side has at least an opening (11,12) therethrough for receiving said actuator (70) and mounting means (13) which are adjacent to said opening (11,12) for securing said actuator (70) thereto. The head-disk enclosure assembly according to claim 1, 2 or 3 wherein said base (6) includes confronting surfaces (45) along the outer margins of said planar interface (20) which confine said gasket means (21) and said cover number (24). A head-disk enclosure assembly according to any one of the preceding claims wherein said interface surface (20) extends above an upper disk surface at said one side of said disks (8) and extends below a lowermost disk surface at another side of said disks (8) opposite to said one side.

Inventors: BRATVOLD, DARRELL EUGENE, LUOMA, RICHARD WILLIAM
Applicants: INTERNATIONAL BUSINESS MACHINES CORPORATION
Application year: 1986
Main classification: G11B25
IPC codes: G11B33, G11B25, G11B17