WO1998037559A1

WO1998037559A1 - Streamlined actuator arm

Info

Publication number: WO1998037559A1
Application number: PCT/US1998/003571
Authority: WO
Inventors: Joaquim A. Bento; Kumaraswamy Kasetty
Original assignee: Quantum Corporation
Priority date: 1997-02-24
Filing date: 1998-02-24
Publication date: 1998-08-27
Also published as: AU6183598A

Abstract

An actuator assembly for a disk drive is provided herein. The actuator assembly includes a plurality of spaced apart actuator arms (16) for holding data transducers (18) proximate the storage surfaces (32) of spaced apart, rotating storage disks (12). Opposed edges (46) of each of the actuator arms are aerodynamically streamlined (Figures 4 and 6) to minimize aerodynamic drag and turbulence between the actuator arms and the rotating storage disks. This significantly reduces the power consumption of the disk drives having storage disks which rotate in excess of about 10,000 RPM.

Description

STREAMLINED ACTUATOR ARM

FIELD OF THE INVENTION

The present invention relates generally to disk drives for storing data.

More specifically, the present invention relates to a streamlined actuator arm for positioning a data transducer of a disk drive between a pair of rotating disks. The actuator arm is particularly useful for disk drives utilizing a plurality of spaced apart disks, which rotate at 10,000 or more RPM.

BACKGROUND

Disk drives are widely used in computers and data processing systems for storing information in digital form. To obtain higher storage capacities, disk drives have evolved from utilizing a single rotating, storage disk, to utilizing a plurality of spaced apart, rotating, storage disks. Typically, an actuator assembly, having a plurality of spaced apart actuator arms, is used for positioning a data transducer proximate each data storage surface of each storage disk.

The need for compact construction of the disk drive has led to the use of smaller disks and minimal separation between consecutive disks. With these systems, the accurate and stable positioning of each data transducer proximate each data storage surface is critical to the transfer and retrieval of information from the rotating disks.

The need to rapidly access information has led to disk drives having storage disks which are rotated at ever increasing speeds. Presently, disk drives having disks which rotate at about 7,200 RPM are currently available. However, high speed disk drives which rotate at 10,000 or more RPM are presently being designed.

Unfortunately, the increased rotational speed of the disks results in increased power consumption of the disk drive. Computer OEM manufacturers are requesting that disk drives use a maximum of 30 watts of power. However, prototype disk drives that utilize twelve disks which spin at about 10,000 RPM, require approximately 35 watts of power. A significant portion of this power consumption is attributed to aerodynamic drag. Further, future disk drives having disks which spin in excess of about 14,000 RPM will consume even more power. Moreover, the increased rotation speeds result in increased air turbulence and increased friction-generated heat between the actuator arms, the data transducers and the rotating disks. The increased turbulence reduces the stability of the actuator arms, the data transducers and the rotating disks. The reduced stability can cause errors in data transfers or a crash between the data transducer and the disk drive. The friction generated heat causes thermal expansion, which causes data losses due to inaccuracies in the positioning of the data transducer relative to the rotating disks.

In light of the above, it is an object of the present invention to provide a stable and efficient disk drive having disks which rotate at 10,000 or more RPM. Another object of the present invention is to provide a high speed disk drive having increased performance and reduced power consumption. Still another object of the present invention is to provide an actuator assembly for a disk drive having actuator arms which are stable at 10,000 or more RPM.

SUMMARY

The present invention is directed to an actuator arm for a disk drive which satisfies these objectives. As described in detail below, the actuator arm includes a streamlined shape which reduces aerodynamic drag between the actuator arm and the rotating disks. The reduced drag reduces the power consumption of the disk drive and reduces friction-generated heat. Further, because of the streamlined shape, the actuator arm is subjected to less turbulent airflow and the positioning of the data transducer is more accurate and stable.

The actuator arm provided herein is useful for positioning a data transducer between a pair of spaced apart, rotating storage disks. The actuator arm includes a proximal section, a distal section and a pair of substantially opposed edges. The proximal section is attached to an actuator hub, while the distal section retains the data transducer adjacent one of the rotating disks.

The edges extend between the proximal section and the distal section. At least one of the edges includes an aerodynamically streamlined portion which reduces the aerodynamic drag and turbulence between the actuator arm and the rotating disks. Preferably, both edges are aerodynamically streamlined to minimize aerodynamic drag and turbulence. For example, each of the edges can have a substantially semi-circular cross-section. In this embodiment, both edges have an arched shape. Alternately, each of the edges can have a substantially triangular cross-section. Additionally, an actuator assembly having features of the present invention includes a plurality of spaced apart, substantially parallel aerodynamic actuator arms secured to the actuator hub which is driven by a voice coil motor. This actuator assembly is particularly suited for a disk drive having a plurality of spaced apart disks which rotate at greater than about 10,000 RPM.

Typically, each actuator arm has a thickness which is between about 0.5 mm to 1.2 mm. Further, the actuator arms 16 are typically spaced apart a distance of between about 1.5 mm and 2.5 mm.

The invention also includes a method for accessing information from the pair of spaced apart, rotating storage disks. The method includes rotating the storage disks at an angular velocity of at least 9,000 RPM and positioning at least a distal section of an actuator arm between the pair of rotating disks. As described above, the actuator arm includes a pair of substantially opposed edges, with at least one of the edges including an aerodynamically streamlined section.

Importantly, the unique design of each actuator arm reduces the aerodynamic drag between each of the actuator arms and the rotating disks.

This reduces the power consumption of the disk drive and reduces turbulent airflow between the actuator arms and the disks. The result is a more efficient, stable and accurate disk drive.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

Figure 1 is a top plan view of a disk drive having features of the present invention, a top cover from the disk drive has been removed for clarity;

Figure 2 is a side plan view of a portion of the disk drive of Figure 1 with a side wall removed for clarity; Figure 3 is a perspective view of an E-block having features of the present invention;

Figure 4 is a cross-sectional view taken on line 4-4 of Figure 3; Figure 5 is a perspective view of a second version of an E-block having features of the present invention; and Figure 6 is a cross-sectional view taken on line 6-6 of Figure 5. DESCRIPTION

Referring initially to Figures 1 and 2, a disk drive 10 according to the present invention includes a drive housing 11 , a plurality of spaced apart, rotating storage disks 12 and an actuator assembly 14 which includes a plurality of actuator arms 16, a plurality of data transducers 18, and a voice coil motor (VCM) 20. As provided herein, the actuator arms 16 are aerodynamically shaped to reduces aerodynamic drag and turbulence between the actuator arms 16 and the rotating storage disks 12. The reduced drag reduces the energy consumption of the disk drive 10 and reduce friction-generated heat, while the reduced turbulence allows the actuator arms 16 to accurately position the data transducers 18.

A detailed description of the various components of a disk drive 10 is provided in U.S. Patent No. 5,208,712, issued to Hatch et al., and assigned to Quantum Corporation, the assignee of the present invention. The contents of U.S. Patent No. 5,208,712 are incorporated herein by reference. Accordingly, only the structural aspects of a disk drive 10 which are particularly significant to the present invention are provided herein.

The drive housing 11 retains the various components of the disk drive 10. Referring to Figures 1 and 2, the drive housing 11 is formed with a cover 22, a base 24 and side walls 26 which support the cover 22 spaced apart from the base 24. A printed circuit board 28, which carries the electronic components of the disk drive 10 can be attached to the base 24. The printed circuit board 28 can be connected to a computer 30 or word processor. For clarity, the disk drive 10 is shown as being remote from the computer 30 in Figure 2. However, disk drive 10 is typically installed in the case of the computer 30.

The storage disks 12 store data in a form that can be subsequently retrieved if necessary. Magnetic storage disks 12 are commonly used to store data in digital form. For conservation of space, each storage disk 12 preferably includes a data storage surface 32 on each side of the storage disk 12. These storage surfaces 32 are typically divided into a plurality of narrow annular regions (not shown) of different radii, commonly referred to as "tracks."

The storage disks 12 are manufactured by ways known to those skilled in the art. For high speed disk drives 10, surface flatness and finish of each storage disk 12 are particularly important to the dynamic stability of the disk drive 10 and the interaction between each data transducer 18 and each storage surface 32. The embodiment shown in Figure 2 includes five, spaced apart storage disks 12 which are attached to a disk shaft 34. Depending upon the design of the disk drive 10, any number of storage disks 12 can be used with the disk drive

10. For example, the disk drive 10 can include six, nine or twelve storage disks 12.

For a two-sided storage disk 12, the disks 12 are spaced apart a sufficient distance so that at least one data transducer 18 can be positioned proximate each of the storage surfaces 32 of adjacent storage disks 12. To conserve space, the centerline of consecutive disks 12 are typically spaced apart between about 1.5 mm to 2.5 mm.

The disk shaft 34 and storage disks 12 are rotated about a disk axis 36 at a predetermined angular velocity by a disk motor (not shown). The rotation rate of the storage disks 12 varies according to the design of the disk drive 10. Presently, disk drives 10 utilize disks 12 rotated at an angular velocity of about 7,200 RPM. However, the present invention is particularly suited for use with disk drives 10 having disks 12 which rotate at about 9,000 to 10,000 RPM. It is anticipated that technological advances will allow for disk drives 10 having storage disks 12 which rotate at higher speeds, such as about 14,000 or more RPM. The design of the actuator assembly 14 depends upon the design of the disk drive 10 and the design of the voice coil motor 20. In the embodiment shown in the Figures, the actuator assembly 14 is a rotary actuator having a rotary voice coil motor 20 which is secured to an actuator hub 38. In this embodiment, the actuator hub 38 is tubular shaped. Further, in this embodiment, the actuator hub 38 is mounted to an actuator shaft 39 which rotates relative to an actuator bearing assembly (not shown). This allows the actuator hub 38 to rotate about a hub axis 40 which is substantially parallel with the disk axis 36.

The actuator arms 16 rotate with the actuator hub 38 and position the data transducers 18 between the disks 12, proximate the storage surfaces 32. Each actuator arm 16 includes a proximal section 42, a distal section 44 and a pair of substantially opposed edges 46. In the embodiment shown in Figures 3 and 5, the proximal section 42 of actuator arms 16 is attached to the actuator hub 38 and the distal section 44 of each of the actuator arms 16 extends away from the actuator hub 38 in a cantilevered fashion. This structure is commonly referred to as an "E-block."

Referring again to Figures 3 and 5, the distal section 44 of each actuator arm 16 can have a substantially rectangular cross-section and include one or more internally threaded transducer holes 48 configured to receive load bolts 50 to facilitate attaching the data transducers 18 to the actuator arms 16.

The opposed edges 46 extend from proximate the distal section 44 to proximate the proximal section 42 of each of the actuator arms 16. As can best be seen with reference to Figures 3-6, at least one of the edges 46 includes an aerodynamically streamlined portion which reduces the aerodynamic drag between the actuator arm 16 and the rotating disks 12 when the distal section 44 is positioned between the rotating disks 12. Depending upon the direction of rotation of the disks 12, one of the edges 46 is considered a leading edge while the other edge 46 is considered a trailing edge. Preferably, at least the leading edge includes the aerodynamically streamlined portion to reduce aerodynamic drag. Even more preferably, both edges 46 are aerodynamically streamlined to minimize aerodynamic drag and turbulence. In the embodiment shown in Figures 3 and 4, each edge 46 has a substantially semi-circular cross-section which defines the aerodynamic streamlined portion. In this embodiment, both edges 46 have an arch shape. Alternately, in the embodiment shown in Figures 5 and 6, each of the edges 46 has a substantially triangular cross-section which defines the aerodynamic streamlined portion.

Importantly, it is the unique design of the edges 46 that reduces the aerodynamic drag between each of the actuator arms 16 and the rotating disks 12. This results in reduced power consumption of the disk drive 10 and reduced turbulent air flow between the actuator arms 16 and the disks 12. For example, it is estimated that the unique design of the edges 46 can reduce power consumption by about eight to ten percent for a disk drive 10 having six disks 12 which rotate at about 10,000 RPM. However, the amount of reduction in energy consumption varies according to a number of factors, such as, the number of disks 12, the rotation speed of the disks 12, the spacing between the disks 12 and the thickness 52 of each actuator arm 16.

The actuator arms 16 must be rigid enough to resist overshoot and lateral vibrations caused by starting accelerations and stopping decelerations of the actuator arms 16 during positioning of the data transducers 18 and/or vibrations caused by turbulent air flow. Accordingly, the design of the actuator arms 16 varies according to the design of the disk drive 10.

In the embodiment shown in Figures 3 and 5, the width 54 of each actuator arm 16 tapers from the proximal section 42 to the distal section 44. The amount of taper can vary according to the design of actuator hub 38 and the design of the disk drive 10. Typically, the width 54 tapers between about eight to twenty degrees. This taper can be symmetrical or asymmetrical.

Each actuator arm 16 has a thickness 52 which varies between about 0.5 mm and 1.2 mm. Additionally, it is anticipated that the thickness 52 of each actuator arm 16 can be varied or tapered between the proximal section 42 and the distal section 44.

Additionally, each actuator arm 16 can include one or more arm openings (not shown) to lighten each actuator arm 16 so that each of the actuator arms 16 move with minimal inertia. The size, shape and number of the arm openings must be consistent with the need for each actuator arm 16 to be sufficiently rigid and the need to minimize aerodynamic drag and turbulence.

The number and spacing of the actuator arms 16 varies according to the number and spacing of the disks 12. For example, the disk drive 10 shown in Figure 2 includes five disks 12 and six actuator arms 16. For this disk drive 10, the distance 56 between the centerline of consecutive actuator arms 16 is between about 1.5 mm to 2.5 mm.

Preferably, the actuator arms 16 and the actuator hub 38, i.e., the E-block is manufactured as a unitary structure for ease of manufacturing and to reduce the stress, weight and air resistance caused by connections or joints. Many processes can be used to make the E-block. For example, the E-block could be extruded and machined to the proper dimensions. Alternately, the E-block could be injection molded. Suitable materials for the E-block are an aluminum alloy, a magnesium alloy, or a ceramic material. Alternately, the E-block may be formed as separate pieces which are attached together by suitable joining techniques known by those skilled in the art.

Referring to Figures 1 and 2, a load beam 60 is commonly used to attach each data transducer 18 to one actuator arm 16. Typically, each load beam 60 is attached to one actuator arm 16 with the load bolt 50 which is secured to the transducer hole 48 in the distal section 44. Alternately, each load beam 60 can be attached by ways known by those skilled in the art.

Typically, each load beam 60 is flexible in a direction perpendicular to the storage disk 12 and acts a spring for supporting one data transducer 18. As the disks 12 rotate, air flow between the data transducer 18 and storage disk 12 causes the data transducer 18 to ride at an aerodynamically stabilized distance from the storage surface 32 of the storage disk 12. Each load beam 60 is resilient and biased to urge each data transducer 18 towards the storage surface 32. Typically, a single data transducer 18 interacts with a single storage surface 32 on one storage disk 12 to access or transfer information to the storage disk 12. For a magnetic storage disk 12, the data transducer 18 is commonly referred to as a read/write head. To read or access data from a magnetic storage disk 12, the data transducer 18 produces electronic read signals in response to the passage of magnetic polarized regions on the storage surface 32 of the disk 12. To write or transfer data to the disk 12, the data transducer 18 generates a magnetic field which is capable of polarizing the desired region of the storage surface 32. It is anticipated that the present device can be utilized for data transducers

18 other than read/write heads for a magnetic storage disk 12. For example, the present invention may be used with an electrooptical transducer for accessing data stored on optical disks 12.

Typically, a data transducer 18 is attached to the load beam 60 by an adhesive (not shown). Alternately, the data transducer 18 can be attached by ways known by those skilled in the art.

The VCM 20 drives the actuator assembly 14 to precisely move the actuator hub 38, actuator arms 16 and the data transducers 18 relative to the storage disks 12 to obtain access to the desired track on the storage surface 32. The voice coil motor 20 can be implemented in a number of alternate ways known by those skilled in the art. As previously mentioned, in the embodiment shown in the Figures, the actuator assembly 14 is a rotary actuator, having a rotary VCM 20, which moves along an arcuate path with respect to the storage surface 32. In this embodiment, a flat, trapezoidal coil 62 is attached to the actuator hub 38. The coil 62 is disposed between two permanent magnets 64 and flux return plates 66. Current passing through the coil 62 causes the actuator hub 38 and the actuator arms 16 to rotate. Alternately, for example, the actuator assembly 14 could be a linear actuator, having a linear voice coil motor 20, which moves radially with respect to the disks 12. Typically, one or more electrical conductors (not shown) extend along the surface of the actuator arm 16 to form electrically-conductive paths between data transducer 18 and the printed circuit board 28. The electrical conductors may be applied to the actuator arm 16 using conventional printed-circuit techniques, known by those skilled in the art. Importantly, the actuator arms 16 disclosed herein are aerodynamically shaped to reduce aerodynamic drag and turbulence between the actuator arms 16 and the rotating storage disks 12. The reduced drag reduces the energy consumption of the disk drive 10 and the reduced turbulence allows the actuator arms 16 to accurately position the data transducers 18 adjacent to the storage disks 12.

While the particular disk drive 10 as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

What is claimed is:

1. An actuator arm for positioning a data transducer between a pair of spaced apart, rotating storage disks, the actuator arm comprising: a proximal section; a distal section which is suitable for retaining the data transducer between the rotating disks, adjacent one of the storage disks; and a pair of substantially opposed edges which extend substantially between the proximal section and the distal section, at least one of the edges includes an aerodynamically streamlined portion which reduces the aerodynamic drag between the actuator arm and the rotating disks when the distal section is positioned between the pair of rotating disks.

2. The actuator arm of claim 1 wherein the streamlined portion is proximate the distal section.

3. The actuator arm of claim 1 wherein at least one of the edges, from proximate the proximal section to proximate the distal section is shaped to be aerodynamically streamlined.

4. The actuator arm of claim 1 wherein at least one of the edges has a substantially semi-circular cross-section proximate the distal section.

5. The actuator arm of claim 1 wherein each of the edges has a substantially semi-circular cross-section.

6. The actuator arm of claim 1 wherein, at least one of the edges has a substantially triangular cross-section proximate the distal section.

7. The actuator arm of claim 1 wherein, each of the edges has a substantially triangular cross-section.

8. The actuator arm of claim 1 having a thickness, proximate the distal section, which is less than about 1.2 mm.

9. An actuator assembly comprising a plurality of spaced apart, substantially parallel actuator arms of claim 1 secured to an actuator hub.

10. A disk drive having reduced power consumption comprising the actuator assembly of claim 9 and a plurality of spaced apart disks selectively rotating at an angular velocity which is greater than about 10,000 RPM.

11. An actuator assembly for positioning a plurality of data transducers between a plurality of rotating storage disks, the actuator assembly comprising: an actuator hub which is selectively rotatable about a hub axis; and a plurality of spaced apart, substantially parallel, actuator arms extending away from the actuator hub, each actuator arm having a proximal section which is attached to and moves with the actuator hub, a distal section which retains at least one data transducer proximate one of the disks, and a pair of substantially opposed edges which extend substantially between the proximal section and the distal section, at least one of the edges is shaped to be aerodynamically streamlined.

12. The actuator assembly of claim 11 wherein at least one of the edges has a substantially semi-circular cross-section proximate the distal section.

13. The actuator assembly of claim 11 wherein each of the edges has a substantially semi-circular cross-section.

14. The actuator assembly of claim 11 wherein, at least one of the edges has a substantially triangular cross-section proximate the distal section.

15. The actuator assembly of claim 11 wherein, each of the edges has a substantially triangular cross-section.

16. The actuator assembly of claim 11 having a thickness, proximate the distal section, which is less than about 1.2 mm.

17. An actuator assembly of claim 11 wherein the actuator arms are spaced apart a distance which is less than about 2.5 mm.

18. A disk drive having reduced power consumption comprising the actuator assembly of claim 11 and a plurality of spaced apart disks selectively rotating an angular velocity which at least is about 10,000 RPM.

19. A reduced power consumption method for accessing information from a pair of spaced apart, high speed, rotating storage disks, the method comprising the steps of: rotating the pair of spaced apart storage disks at an angular velocity of at least about 9,000 RPM; and positioning a distal section of an actuator arm between the pair of rotating disks, the actuator arm including a pair of substantially opposed edges, at least one of the edges including an aerodynamically streamlined section.

20. The method of claim 19 wherein the pair of storage disks are rotated at an angular velocity of at least about 10,000 RPM.

21. The method of claim 19 wherein the pair of storage disks are rotated at an angular velocity of at least about 14,000 RPM.