WO2001037267A1

WO2001037267A1 - Disk drive assembly

Info

Publication number: WO2001037267A1
Application number: PCT/US1999/027032
Authority: WO
Inventors: F. Wayne Petersen; Alvin Pavelka; Gale Johnson
Original assignee: CONNER TECHNOLOGY PLC
Current assignee: CONNER TECHNOLOGY PLC
Priority date: 1999-11-13
Filing date: 1999-11-13
Publication date: 2001-05-25
Anticipated expiration: 2002-05-13

Abstract

A disk drive assembly (10) including a disk clamp (12), an actuator arm assembly system (30), a latch device (60), a base cover (80), and a top cover (100). The disk drive assembly (10) of the present invention can include the disk clamp (12), as described, without including the actuator arm assembly (30), the disk drive assembly (10) can include the actuator arm assembly (30), as described, without including the latch device (60), and so on. For optimum performance, the disk drive assembly (10) will include each and every element.

Description

DISK DRIVE ASSEMBLY Inventors: F. Wayne Petersen, Alvin Pavelka and Gale Johnson

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to disk drive assemblies used with an information processing system, and, more particularly, it relates to various components of a disk drive assembly including in combination, but not limited to, a disk clamp, an actuator arm assembly, a latch device, a base cover, and a top cover for the disk drive assembly.

2. Description of the Prior Art Generally, the hard disk drive used as a memory device, and more particularly as an auxiliary memory device in an information processing system, such as a computer includes at least one two sided read write disk which is rotated at a high speed on a spindle by a spindle motor, and an actuator arm assembly which rotates in response to a voice activated coil motor about a pivot point to move a read write transducer, such as a magnetic head. The read/write transducer on the actuator arm writes data onto selected tracks of the disk and reads selected data recorded on the tracks of the disk. Each magnetic transducer head is located on a leading end of a head gimbal, which head gimbals are each normally located adjacent to one side of the disk. As the head gimbals move along both sides of the disk, and the disk rotates at a high speed, the magnetic transducers are supported by the airflow generated at the surface of the disk to thereby maintain a small gap between the magnetic transducer on the actuator arm and the disk. The elements of the hard disk drive are typically situated within a base plate housing covered by a top plate. The interior of the disk drive is sealed from exterior contamination by a gasket positioned between the base plate and the housing. When the hard disk drive stops rotating, or powers off during the above-mentioned operation, the actuator arm assembly is designed to move the actuator arms and the magnetic transducer into a parking zone located on an inner or an outer portion of the housing within the tracks of the disk. The actuator a ms and the magnetic transducers are moved into the parking zone on the disk by the residual inertia of a spindle motor. This movement of the actuator arm and the magnetic transducers is designed to prevent the data recorded on the disk from being damaged by the contact of the magnetic transducer with the magnetic surface of the disk. For securely fixing or latching a rear end of the actuator arm assembly during the above operation, a mechanism such as a solenoid, a separate voice activated coil motor, or a magnetic latch has been employed. Among these mechanisms, the magnetic latch is generally used for economics and other reasons. In the past, a metal plate easily attached to a magnet has been installed to the rear end of the actuator arm assembly, since the rear end of the actuator arm assembly is of a conductive material, such as aluminum, or has a structure to which an electric coil can be attached. Generally, in the case where the structure having the metal plate is used, the metal plate can be attached to the rear end of the actuator arm assembly by using an adhesive material. Since many disk drives have more than one disk, a disk clamp is employed to inhibit the slippage of each disk relative to the disk drive spindle. It is believed by the inventors of the present application that there have been no single screw disk clamps used on a disk drive having a 3.5 inch form factor due to the difficulties in maintaining a secure clamping of the disk or the disks of the disk stack in the larger-size disk drives. The disks are typically stacked on a hub, the hub having a lip located on one end of the hub and contacting the surface of the first disk near the central opening of the disk. Generally, there is a spacer between each disk. The disks and spacers are generally referred to as the disk stack. The term disk stack also applies to a disk drive having only one disk and no spacers. The disk clamp also provides a compressive load on the disk stack to hold the disk or disks in place. The compressive load acts on the inner edge surrounding the central opening ofthe disk or disks in the disk stack, and is in a direction which is coaxial with the axis of the hub. This is referred to as an axial load since it acts in the axial direction. While disk clamps are available in a variety of configurations, the most commonly used disk clamp has multiple screws in order to obtain the desired compressive force.

BRIEF DESCRIPTION OF THE DRAWINGS Features and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the drawings, in which: FIG. 1 is a perspective view illustrating a disk clamp for securing a disk or disks of a disk stack of a disk drive assembly constructed in accordance with the present invention; FIG. 2 is a top view illustrating the disk clamp of FIG. 1 constructed in accordance with the present invention prior to the disk clamp being tightened against the disk or disks of the disk stack of the disk drive assembly, FIG. 3 is a side view illustrating the disk clamp of FIG. 2 constructed in accordance with the present invention in its free state; FIG. 4 is a top view illustrating the disk clamp of FIG. 1 constructed in accordance with the present invention as it will appear subsequent to the disk clamp being tightened to the engage the disks or disks of the disk stack of the disk drive assembly; FIG. 5 is a side view illustrating the disk clamp of FIG. 4 constructed in accordance with the present invention; FIG. 6 is an enlarged top view illustrating the disk clamp constructed in accordance with the present invention prior to the disk clamp being tightened against the disk or disks of the disk stack of the disk drive assembly; FIG. 7 is a side view illustrating the disk clamp of FIG. 6 constructed in accordance with the present invention; FIG. 8 is a perspective view illustrating an actuator arm assembly of the disk drive assembly constructed in accordance with the present invention; FIG. 9 is a top view illustrating the actuator arm assembly of FIG. 8 constructed in accordance with the present invention; FIG. 10 is a side view illustrating the actuator arm assembly of FIG. 8 constructed in accordance with the present invention; FIG. 11 is a bottom view illustrating the actuator arm assembly of FIG. 8 constructed in accordance with the present invention; FIG. 12 is a side view illustrating a pin portion of an actuator arm assembly latch device of the disk drive assembly, at a larger scale than the actuator arm assembly of FIGS, 8-11, andl constructed in accordance with the present invention; FIG. 13 is a left end view illustrating the pin portion of the actuator arm assembly latch device of FIG. 12 constructed in accordance with the present invention; FIG. 14 is a side view, further enlarged, illustrating a magnet portion of the actuator arm assembly latch device of FIG. 12 of the disk drive assembly constructed in accordance with the present invention; FIG. 15 is a left end view illustrating the magnet portion of the actuator arm assembly latch device of FIG. 14 constructed in accordance with the present invention; FIG. 16 is a side view, in the same scale as FIGS. 14=15, illustrating a cap portion of the actuator arm assembly latch device of FIG. 12 of the disk drive assembly constructed in accordance with the present invention; FIG. 17 is an end view illustrating the cap portion of the actuator arm assembly latch device of FIG. 16 constructed in accordance with the present invention; FIG. 18 is a top view, * AT A SMALLER SCALE THAN THE OTHER* FIGS, illustrating a base cover of the disk drive assembly constructed in accordance with the present invention; FIG. 19 is a side view illustrating the base cover of FIG. 18 constructed in accordance with the present invention; FIG. 20 is an end view illustrating the base cover of FIG. 18 constructed in accordance with the present invention; FIG. 21 is a bottom view illustrating a base cover of the disk drive assembly constructed in accordance with the present invention; FIG. 22 is a side view illustrating the base cover of FIG. 21 constructed in accordance with the present invention; FIG. 23 is an end view illustrating the base cover of FIG. 21 constructed in accordance with the present invention; FIG. 24 is a perspective view, at the same scale as FIGS. 18-23, illustrating a top cover of the disk drive assembly constructed in accordance with the present invention; FIG. 25 is a top view illustrating the top cover of FIG. 24 constructed in accordance with the present invention; FIG. 26 is a side view illustrating the top cover of FIG. 24 constructed in accordance with the present invention; and FIG. 27 is an end view illustrating the top cover of FIG. 24 constructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a disk drive assembly used, for example as an auxiliary memory device in an information processing system, such as a computer. The disk drive assembly of the present invention includes a disk clamp as illustrated in FIGS. 1 - 7, an actuator arm assembly as illustrated in FIGS. 8 - 11 , a latch device as illustrated in FIGS. 12 - 17, a base cover as illustrated in FIGS. 18 - 23, and a top cover as illustrated in FIGS. 24 - 27.

Disk Clamp As illustrated in FIGS. 1 - 7, the present invention includes a disk clamp 12 for maintaining the disk stack (not shown) within the disk drive assembly and inhibiting the disk or disks ofthe disk stack from slipping about the disk hub (not shown). Disk clamp 12 has a center portion 14 that is concentric with an outer rim portion 16. Outer rim portion 16 is sized and positioned to contact the disk or top disk of a disk stack. Disk clamp 12 includes a plurality of radial spokes 18 which connect center portion 14 to outer rim portion 16. Radial spokes 18 maintain the center portion 14 in a relative position above the outer rim portion 16 to define a substantially bell shaped convex disk clamp 12. Center portion 14 includes a screw receiving aperture 20 for receiving a single screw (not shown). The screw extends through screw receiving aperture 20 into the disk hub (not shown) to securely mount the disk stack (not shown) to the disk hub to thereby inhibit the disk or disks ofthe disk stack from slipping or otherwise moving relative to the disk hub. As best shown in FIG. 7, outer rim portion 16 of disk clamp 12 has a substantially U-shaped cross-sectional configuration. A contacting point 22 on outer rim portion 16 contacts a disk or top disk ofthe disk stack. As the screw is tightened through screw receiving aperture 20 of center portion 14, radial spokes 18 flex in a generally downward direction toward the disk stack forcing contacting point 22 into contact with the disk or top disk ofthe disk stack to releasably secure the disk stack about the disk hub. As noted above, disk clamp 12 of the present invention has a substantially bell shape which allows disk clamp 12 to flex in compression as disk clamp 12 is tightened against disk or disks ofthe disk stack. The dimensions, design, materials and flexibility of disk clamp 12 of the present invention causes the appropriate, desired compression force to be applied against the disk or disks ofthe disk stack to inhibit the disk stack from slipping or otherwise moving relative to the disk hub. Furthermore, the bell shape of disk clamp 12 inherently, when deflected only a short distance, applies and builds force rapidly against the disk or disks of the disk stack while being d. As noted above, disk clamp 12 of the disk drive assembly of the present invention has a circular shape and is substantially bell shape in profile. It may be produced easily and inexpensively by stamping it from metal, such as a stainless steel material, although other materials are within the scope ofthe present invention. Furthermore, center portion 14 preferably has a thickness greater than a thickness of outer rim portion 16, this beng easily achieved by selecting a starting blank material having those characteristics. The novel design of disk clamp 12 of the disk drive assembly of the present invention provides the desired and correct compression force on the disk or disks of the disk stack such that the disk or disks of the disk stack does not tend to slip or otherwise move relative to the disk hub of the disk drive assembly. By using a single screw as opposed to multiple screws ofthe prior art, disk clamp 12 ofthe present invention provides a better evenly distributed load on the disk stack. The single screw disk clamp 12 is also easier to manufacture since the assemblers are only required to insert and tighten one screw as opposed to multiple screws. Another unique advantage of disk clamp 12 of the present invention, the single screw disk clamp 12 can be used on any size form factor. Due to the novel design ofthe disk clamp 12 of the present invention, the single screw disk clamp 12 can for the first time actually be used on any size form factor disk drive, even a disk drive having a 3.5 inch form factor or greater, while maintaining the proper and desired amount of compression force to avoid disk stack slippage relative to the disk hub.

Actuator Arm Assembly As illustrated in FIGS. 8 - 11 , the disk drive assembly of the present invention further includes an actuator arm assembly 30 which rotates in response to a voice activated coil motor 44 about a pivot point 33 within a bore 32 for moving a magnetic transducer head (not shown) that writes data onto the tracks of a disk (not shown) and reads data recorded from the tracks of the disk. The actuator arm assembly 30 includes at least one actuator arm 34 for carrying magnetic transducer heads. Each actuator arm 34 has a substantially curved leading side edge 36 having a curve radius substantially equal to the curve radius ofthe disks. Each actuator arm 34 also has a substantially straight trailing side edge 38 that is opposed to each leading side edge 36. Providing the actuator arm 34 with a curved leading side edge 36, allows the optimization of the installation of actuator arm assembly 30 between the disks of a disk stack in the disk drive assembly ofthe present invention. The curved leading side edge 36 of each of actuator arms 30 optimizes the coil stroke of actuator arm assembly 30 and allows actuator arms 34 to be positioned directly adjacent the disk or disks ofthe disk stack prior to installation thereby simplifying the magnetic transducer head loading process. The actuator arm assembly 30 ofthe present invention further includes a first voice activated coil retaining member 40 adjacent to the leading side edge 36 of actuator arm assembly 30 and a second voice activated coil retaining member 42 adjacent the trailing side edge of actuator arm assembly 30. The first voice activated coil retaining member 40 and second voice activated coil retaining member 42 secure voice activated coil motor 44 there between. Preferably, first voice activated coil retaining member 40 has a size and shape different from the size and shape ofthe second voice activated coil retaining member 42. In the particular embodiment of actuator arm assembly 30 illustrated in FIGS 8 - 11, first retaining member 40 has a size greater than the size of second retaining member 42. By providing the first voice activated coil retaining member 40 and the second voice activated coil retaining member 42 of actuator arm assembly 30 with different shapes, first retaining member 40 and second retaining member 42 will not tend to resonant at the same frequency. Therefore, any vibrational or shock typically associated with the rotation of actuator arm assembly 30 about pivot point 33 is substantially inhibited. The actuator arm 34 of actuator arm assembly 30 of the disk drive assembly of the present invention further includes at least one aperture 46 formed in actuator arm 34 for reducing the weight of actuator arm 34. As best illustrated in FIG. 9, the apertures 46 are preferably formed to one side of a centerUne 48 of actuator arm assembly 30, and closely adjacent trailing side edge 38 of actuator arm 30. In the past, the actuator arm assembly has been fastened to the disk drive assembly by a screw inserted into a central bore. However, the present invention includes a bore 32 which includes a plastic material 44 over molded within the aperture of bore 32. The over molded plastic material 44 within bore 32 allows actuator arm assembly 30 to be press-fit mounted to disk drive assembly 30 without requiring any additional fastening mechanisms, such as a screw. Regardless of the asymmetrical shape of actuator arm assembly 30 of the present invention, actuator arm 34 of actuator arm assembly 30 is symmetrically balanced about a pivot point 33, i.e. it is balanced on both the leading side edge 36 and the trailing side edge 38, along center line axis 48 and along its transverse line axis 50. If actuator arm 34 ofthe present invention were divided into four quadrants about pivot point 33 , each of the quadrants would have substantially the same weight and, therefore, the actuator arm assembly 30 is perfectly balanced about pivot point 33.

Actuator Arm Assembly Latch Device As illustrated in FIGS. 12 - 17, the disk drive assembly ofthe present invention additionally includes an actuator arm assembly latch device 60. When the disk drive assembly of the present invention is placed in a power-off mode, ofthe latch device 60 serves to move the magnetic transducer heads into a parking zone located on an inner portion ofthe disk. The latch device 60 ofthe present invention includes a pin portion 62, as illustrated in FIGS. 12 - 13, a magnet portion 64, as illustrated in FIGS. 14 - 15, and a cap portion 66, as illustrated in FIGS. 16 - 17, with magnet portion 64 sandwiched between pin portion 62 and cap portion 66. As illustrated in FIGS. 12 - 13, pin portion 62 has a mounting end 68, a shaft 70 connected to mounting end 68, and a magnetic receiving end 72 connected to shaft 70. The mounting end 68 is press-fit into the disk drive assembly for releasably securing latch device 60 to the disk drive assembly. Preferably, mounting end 68, shaft 70, and magnet receiving end 72 are constructed from a unitary piece of material, such as stainless steel, although constructing mounting end 68, shaft 70, and magnet receiving end 72 from multiple pieces of stainless steel material, or from other material besides stainless steel, is within the scope ofthe present invention. Furthermore, preferably, cap portion 72 ofthe latch device is also constructed from a stainless steel material. The magnet portion 64 is received within cap end 72 of pin portion 62 and bonded and secured thereto, for example with an adhesive substance. Cap portion 66 is then bonded and secured to magnet 64, preferably, with an adhesive substance. The shaft 70 of pin portion 62 of the latch device 60 is designed and shaped to act as a spring in response to contact with actuator arm assembly 30. As actuator arm assembly 30 swings into the latch device 60, shaft 70 of pin portion 62 deflects and absorbs the shock associated with the actuator arm assembly 30 contacting latch device 60. Magnet 64 contacts a plate 74 (as illustrated in FIG. 8) and maintains actuator arm assembly 30 against latch device 60 until the disk drive assembly is powered on.

Base Cover and Top Cover As illustrated in FIGS. 18 - 23, the disk drive assembly ofthe present invention also includes a metal base cover 80, for example of aluminum. Base cover 80 provides a structure for mounting a disk stack and actuator arm assembly 30 therein. In addition, as illustrated in FIGS. 24 - 27, a top cover 100, also preferably of metal, is provided for covering a disk stack and actuator arm assembly 30 mounted within base cover 80. Base cover 80 has a plate 82 and a sidewall 84 surrounding the periphery of plate 82. Sidewall 84 of base cover 80 has a plurality of notches 86 formed in sidewall 84. Notches 86 allow the disk stack to be easily installed within base cover 80 and also provides access for clocking and writing servo information to the disks. Unlike the disk drives ofthe prior art, the top cover 100 and the base cover 80 ofthe disk drive assembly ofthe present invention is free from any clock and servo writing openings, and is therefore free from labels typically covering these openings in top cover 100 and base cover 80. In fact, the only opening present in base cover 80 is a slot 88 for a connector (not shown) which has a gasket (not shown) there around for preventing foreign materials from entering the closed disk drive assembly. Being free from labels is extremely important since, in the prior art the label's organic adhesive materials or their solvents tend to outgas into the disk drive, thereby affecting the long term reliability ofthe prior art disk drives. The combined and closed top cover 100 and base cover 80 of the disk drive assembly ofthe present invention has no labels and, thus, has no adhesive outgas problems. With the disk drive assembly ofthe present invention, top cover 100 has a plate 102 and a side wall 104 surrounding the periphery of plate 102. As top cover 100 is mounted to base plate 80, the side wall 104 of top cover 100 slides over the side wall 84 of base cover 80 to encapsulate the side wall 84 of base cover 80. The side wall 104 of top cover 100 further covers notches 86 formed in side wall 84 of base cover 80, thereby further preventing foreign materials from entering the closed disk drive assembly. Both the base cover 80 and top cover 100 are constructed such that neither base cover 80 nor top cover 100 are vibrationally excited by the spindle motor (not shown). A plurality of ribs or stiffening members 90 are formed on base cover 80 and a stiffening member 106 is formed on top cover 100. Together with side walls 84 and 104 stiffening members 90 and 106 inhibit the vibrational excitation of both base cover 80 and the top cover 100. Furthermore, the inhibiting ofthe vibration and shock associated with the spindle motor allows the spindle motor to be attached solely to base cover 80 without having to also attach the spindle motor to top cover 100. As opposed to disk drives of prior art wherein a gasket separates the top cover from the base plate, having the side wall 104 of top cover 100 overlap the side wall 84 of base cover 80 as in the present invention, the metal base cover 80 and top cover 100 ofthe disk drive assembly ofthe present invention provides excellent EMI and EMC shielding. The disk drive assembly is not susceptible to interference due to elecytronic noise generated by other components in the computer system. Furthermore, due to the overlapping relationship between base cover 80 and top cover 100, only minimal EMI and EMC noise, if any, is emitted from the disk drive assembly during its operation. It is therefore seen that the disk drive assembly 10 of the present invention has been described as including a disk clamp 12, the actuator arm assembly system 30, the latch device 60, the base cover 80, and the top cover 100. A person skilled in the art will understand that any of the above elements can be utilized in the disk drive assembly without the other elements. For example, the disk drive assembly ofthe present invention can include the disk clamp 12, as described, without including the actuator arm assembly 30, the disk drive assembly 10 can include the actuator arm assembly 30, as described, without including the latch device 60, etc. For optimum performance, of course, the disk drive assembly will include each and every element. The foregoing exemplary descriptions and the illustrative preferred embodiments of the present invention have been explained in the drawings and described in detail, with varying modifications and alternative embodiments being taught. While the invention has been so shown, described and illustrated, it should be understood by those skilled in the art that equivalent changes in form and detail may be made therein without departing from the true spirit and scope ofthe invention, and that the scope ofthe present invention is to be limited only to the claims except as precluded by the prior art. Moreover, the invention as disclosed herein, may be suitably practiced in the absence of the specific elements which are disclosed herein.

Claims

We claim: 1. A disk clamp for maintaining a disk stack within a disk drive assembly for inhibiting a disk or disks of a disk stack from slipping about the disk hub of a disk drive assembly, comprising: a center portion concentric with a circular outer rim, said center portion being joined to said circular outer rim by a plurality of normally upwardly extending radial spokes to thereby maintain said center portion in a position relatively above said outer rim portion; and means associated with said center portion for securing said disk clamp to a disk hub, thereby causing said center portion to compress downwards towards said circular outer rim to press said outer rim against a disk; whereby a stack is securely mount to a disk hub to inhibit the disk or disks of the disk stack from slipping or otherwise moving relative to the disk hub.

2. The disk clamp of claim 1 wherein said normally upwardly extending radial spokes are convexly curved to form a substantially bell shaped convex disk clamp which is easily compressed downwards towards said circular outer rim.

3. The disk clamp of claim 1 wherein said means associated with said center portion for securing said disk clamp to a disk hub is designed to utilize mechanical connecting means.

4. The disk clamp of claim 3 wherein said mechanical connecting means is one or more screw.

5. The disk clamp of claim 3 wherein said means associated with said center portion for securing said disk clamp to a disk hub is one or more screw receiving aperture.

6. The disk clamp of claim 5 wherein said means associated with said center portion for securing said disk clamp to a disk hub is a single screw receiving aperture for receiving a single screw.

7. The disk clamp of claim 1 wherein at least a part of said outer rim portion has a substantially upwardly open U-shaped cross-sectional configuration with a curved bottom which is designed and configured to contact a disk or top disk of a disk stack; whereby, as said means for securing said disk clamp to a disk hub is activated to urge said center portion toward the disk stack, said radial spokes flex in compression in a generally downward direction forcing said contact parts into contact with the disk or top disk ofthe disk stack to releasably secure a disk stack about a disk hub.

8. The disk clamp of claim 1 wherein said center portion has a thickness greater than the thickness of said outer rim.

9. The disk clamp of claim 1 wherein said center portion is circular.

10. An actuator arm assembly which rotates in response to an activating motor for use with a disk drive assembly to move a transducer head, the disk drive assembly being designed to carry recording disks or a a disk stack, including: at least one actuator arm for carrying at least one transducer head, each actuator arm having a leading side edge which is curved, the curved leading side edge having a curve radius substantially equal to the curve radius ofthe disks that will be carried by the disk assembly, and each actuator arm also having a trailing side edge opposed to each curved leading side edge, said trailing side edge being substantially straight; wherein said curved leading side edge allows the optimization ofthe installation of each actuator arm assembly between the disks of a disk stack in a disk drive assembly to optimize the action of the activating motor of the actuator arm assembly, and allow the actuator arms to be positioned directly adjacent to the disk or disks ofthe disk stack prior to installation, thereby simplifying the transducer head loading process.

11. The actuator arm assembly of claim 10 wherein a mounting retaining member is adjacent said curved leading edge and a magnet receiving end retaining member is adjacent said straight trailing edge, wherein said activating motor is a voice activated coil motor, and wherein further there are two voice activated coils, said mounting voice activated coil being adjacent said mounting retaining member adjacent to its said curved leading side edge of said actuator arm assembly ,and said magnet receiving end voice activated coil retaining member being adjacent said straight trailing side edge of said actuator arm assembly, said voice activated coil motor being operatively connect to and in between said mounting voice activated coil retaining member and said magnet receiving end voice activated coil motor retaining member

12. The actuator arm assembly of claim 11 wherein said mounting voice activated coil retaining member has a weight and shape different from the weight and shape of said magnet receiving end voice activated coil retaining member, whereby said mounting retaining member and said magnet receiving end retaining member will not tend to resonant at the same frequency so that any vibrational or shock typically associated with the rotation of said actuator arm assembly is substantially inhibited.

13. The actuator arm assembly of claim 12 wherein said mounting retaining member has a weight greater than the weight of said magnet receiving end retaining member.

14. The actuator arm assembly of claim 11 wherein said actuator arm assembly includes a portion which defines a bore defining an aperture, having a plastic material over molded within said aperture of bore; whereby said over molded plastic material within said bore allows said actuator arm assembly to be press-fit mounted to said disk drive assembly without requiring any additional fastening mechanisms.

15. The actuator arm assembly of claim 14 wherein, regardless of the asymmetrical shape of said actuator arm assembly said actuator arm assembly is symmetrically balanced about a pivot point defined by an imaginary line between said leading side edge and said trailing side edge at the point at which it intersects said center of said bore; whereby, if actuator arm were divided into four quadrants about said center of said bore, each ofthe quadrants would have substantially the same weight so that said actuator arm assembly is perfectly balanced about said center of said bore.

16. The actuator arm assembly of claim 11 wherein said disk drive assembly includes an actuator arm assembly latch device, which latch device, when said disk drive assembly is placed in a power-off mode serves to move said transducer head into a parking zone located on an inner portion ofthe disk.

17. The actuator arm assembly of claim 16 wherein said latch device includes a pin portion having a mounting end, a magnet receiving end and a shaft there-in-between, a magnet portion, connected to said magnet receiving end of said pin portion, and a cap portion, with said magnet portion sandwiched between said magnet receiving end of said pin portion, and cap portion, said mounting end of said pin portion being press-fit into the disk drive assembly for releasably securing said latch device to said disk drive assembly, said latch device, said shaft being designed and shaped to act as a spring in response to contact with said actuator arm assembly when said actuator arm assembly swings into said latch device, with said shaft of said pin portion deflecting and absorbing the shock associated with said actuator arm assembly contacting said latch device, and said magnet contacts a magnetically permeable plate to maintains said actuator arm assembly in contact with said latch device until the disk drive assembly is powered on.

18. The latch device of claim 11 wherein said shaft, and said magnet receiving end are constructed from a unitary piece of material.

19 A disk drive assembly including a metal base cover for mounting a disk stack and actuator arm assembly therein, and a metal top cover for covering a disk stack and actuator arm assembly mounted within said base cover, comprising: said cover having a plate and a sidewall 84 surrounding the periphery of said plate, said sidewall of said base cover having a plurality of notches formed therein to allow the disk stack to be easily installed within said base cover, said notches also providing access for clocking and writing servo information to the disks, said base cover being free from labels and other materials or solvents which tend to outgas into the disk drive, thereby avoiding deterioration ofthe long term reliability of the disk drives.

20. The disk drive assembly of claim 19 in which the combined and closed top cover and base cover has no outgassing materials.

21. The disk drive assembly of claim 19 in which said top has a plate and a side wall 104 surrounding the periphery of plate, whereby when said top cover is mounted to said base plate, said side wall slides over said side wall of said base cover to encapsulate said side wall of said base cover; thereby both providing EMI and EMC shielding and preventing foreign materials from entering the closed disk drive assembly.