WO1994029862A1

WO1994029862A1 - Rolling actuator bearing

Info

Publication number: WO1994029862A1
Application number: PCT/US1994/004537
Authority: WO
Inventors: Harold J. Beecroft
Original assignee: Maxtor Corporation
Priority date: 1993-06-09
Filing date: 1994-04-25
Publication date: 1994-12-22
Also published as: AU6818794A

Abstract

A bearing assembly for an actuator arm (22) of a hard disk drive unit. The assembly includes a cylindrical bearing block (26) which extends from a baseplate. The bearing block has a V-shaped slot with a first apex at the center of the block. The actuator arm has a triangular shaped pivot bearing (30) which extends into the V-shaped slot of the bearing block. The pivot bearing has a second apex which is in contact with the first apex of the slot and allows the actuator arm to rotate relative to the block. The pivot bearing is pushed into contact with the block by a clip (34). The clip has a first arm which is in contact with the bearing block and a second arm which is in contact with an arcuate surface of the actuator arm.

Description

ROLLING ACTUATOR BEARING

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to a bearing assembly for the actuator arm of a hard disk drive unit.

2. DESCRIPTION OF RELATED ART

Hard disk drive assemblies contain a magnetic disk which rotates relative to a magnetic head. The disk is typically mounted to a hub that is rotated by an electric motor. The magnetic head is attached to an actuator arm assembly which can move the head relative to the disk. The actuator arm is coupled to the housing of the disk drive by a bearing assembly, which allows the magnetic head to rotate relative to the surface of the disk. The actuator arm typically has a coil that is coupled to a magnet mounted to the base plate of the drive unit. The actuator assembly arm is coupled to a control circuit which energizes the coil and moves the magnetic head.

The head magnetizes and senses the magnetic field of the magnetic disk in accordance with a scheme to read and write binary information on the disk. The magnetic disk typically contains separate annular tracks located throughout the surface of the disk. The actuator arm moves the head to one of the tracks in accordance with commands from the control circuit. Moving the head from track to track requires a high degree of accuracy in the rotation of the actuator arm. For this reason, the bearing assembly of the arm must provide consistent accurate movement of the head.

The Personal Computer Memory Card International Association (PCMCIA) recently promulgated a specification which standardizes the dimensions of the memory/logic cards of a computer. The cards are configured so that the user can readily remove a card from one computer system and plug the memoiy/logic unit into another computer system, regardless of the make or type of system.

It would be desirable to provide a hard disk drive unit that can be constructed to meet the PCMCIA format. The dimensions for the PCMCIA cards are approximately the size of a credit card, requiring thicknesses that are not greater than 10.5 millimeters. Producing a conventional hard disk drive unit that meets the PCMCIA specification would require the implementation of extremely small ball bearings. Ball bearings of such size would be susceptible to damage when subjected to excessive shock loads. The application of excessive shock loads is more likely to occur with a portable hard disk drive which is designed to be carried and handled by the user. It would therefore be desirable to have a actuator bearing assembly which is rugged and can meet the profile requirements of the PCMCIA memory/logic cards.

SU MARY OF THE INVENTION

The present invention is a bearing assembly for the actuator arm of a hard disk drive unit. The assembly includes a cylindrical bearing block which extends from a baseplate. The bearing block has a V-shaped slot with a first apex at the center of the block. The actuator arm has a triangular shaped roller bearing which extends into the V-shaped slot of the bearing block. The roller bearing and slot of the bearing block have radial surfaces which allow the pivot bearing to roll within the block. The pivot bearing is pushed into contact with the block by a clip. The clip has a first arm which is in contact with the bearing block and a second arm which is in contact with the arcuate surface of the actuator arm.

At one end of the actuator arm is a magnetic head. Opposite the head is a magnet which is coupled to a stationary coil mounted to the housing of the drive unit. Energizing the coil moves the magnet and the actuator arm. The pivot bearing allows the actuator arm to pivot about the bearing block. The actuator arm and pivot bearing are preferable constructed from a silicon carbide which is both hard and strong. The pivot bearing and bearing block have a relatively small profile so that the hard disk drive unit can meet the requirements of the PCMCIA memory /logic card specifications, without reducing the strength of the actuator arm assembly.

Therefore it is an object of the present invention to provide a rugged actuator bearing assembly for a hard disk drive that meets the requirements of the PCMCIA memory/ card specifications. BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, wherein:

Figure 1 is a top view of a hard disk drive assembly which has an actuator arm bearing assembly of the present invention;

Figure 2 is an enlarged cross-sectional side view of the bearing assembly of Fig. 1;

Figure 3 is an enlarged top view of the bearing assembly;

Figure 4 is a view similar to Fig. 3 showing the actuator arm rotated to a second position;

Figure 5 is an enlarged top view of the bearing assembly.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings more particularly by reference numbers Figure 1 discloses a hard disk drive 10 with an actuator arm assembly 12 of the present invention. The hard disk drive contains a disk 14 that is rotated by a spin motor 16. The disk 14 is typically constructed from a metal substrate that is covered with a magnetic coating. The disk 14 rotates relative to the actuator arm assembly 12 which has a pair of transducers 18 commonly referred to as heads. The transducers 18 typically contain a coil (not shown) which can magnetize and sense the magnetic field of each corresponding adjacent surface of the disk 14 as is known in the art.

Each head 18 is supported by a flexbeam 20 that is attached to an actuator arm(s) 22. The heads 18 each contain a slider (not shown) which cooperate with the air stream produced by the rotation of the disk to create an air bearing between the surface of the disk and the transducer 18. The air bearing lifts the heads off of the surface of the disk 14. The flexbeams 20 are constructed to be flexible enough to allow the heads to be separated from the disk surface by the air bearings and follow the small variation in the surface of the disk. The actuator arm 22 rotates about a bearing assembly 24.

The relative position between the heads 18 and the disk surfaces should be essentially constant during the life of the disk drive. Movement of the head 18 away from the disk surface will weaken the magnetic field and effect the steps of sensing and magnetizing the magnetic field of the disk. Movement of the head 18 toward the disk 14 may cause contact between the two members and result in undesirable wear between the transducer and disk surface. Therefore the bearing assembly must be relatively rugged and capable of withstanding large shock loads.

As shown in Figures 2-3, the bearing assembly 24 includes a bearing block 26 which extends from a base plate 28. The actuator arm 22 has a triangular shaped roller bearing 30 which extends into a V shaped slot 32 in the block 26. The roller bearing 30 and slot 32 have cylindrical apex surfaces that allow the bearing 30 to roll within the block 26. The roller bearing 30 is pressed into contact with the block 26 by a C shaped spring clip 34. As shown in Fig. 4, the apex of the roller bearing 30 engages the apex of the slot 32 so that the bearing rolls relative to the block 26 when the actuator arm 22 is rotated about the bearing assembly 24. The apex of the bearing 30 provides a point about which the actuator rotates, such that there is not any sliding movement between the roller bearing 30 and block 26. The absence of sliding movement between the roller bearing 30 and block 26 greatly reduces the friction of the bearing assembly 24. As shown in Fig. 5, the clip 34 is assembled so that the clamping force is directed through the center of the radius Rl of the cylindrical apex of the roller bearing 30. the surfaces -A- and -B- of the clip 34 are maintained parallel during rotation of the actuator arm 22. The angle of rotation of the spring clip 34 is a function of the radius R2 and R4 of the outer radial surfaces of the arm 22 and block 26, respectively.

The spring force of the clip 34 is large enough to maintain contact between the roller bearing 30 and the bearing block 26, but low enough to allow the actuator arm 22 to rotate about the bearing assembly 24. The roller bearing of the present invention provides a low profile bearing assembly that produces a relatively small amount of friction and which can withstand the typical shock loads applied to a hand held disk drive. In the preferred embodiment, the apex of the roller bearing 30 can be coated with an elastomeric material to dampen any shock loads that are applied to the bearing assembly 24.

At the end of the actuator arm 22 is a magnet 36 located between a pair of stationary coils 38. The magnet has north (N) and south (S) poles, so that when a current is sent through the coils in one direction, the magnet creates forces perpendicular to the coils 38 and applies a torque to the arm 22 to move the same. Reversing the current creates a torque and corresponding arm movement in an opposite direction. The magnet and coils, commonly referred to as a voice coil 40, rotate the actuator arms 22 and move the heads 18 relative to the disk 14. The coils 38 are mounted to a C shaped shield plate 42 that is constructed from a ferrite or magnetic material. The shield plate 42 provides a return path for the magnetic flux and maintains the flux in the area of the voice coil 40. The disk drive assembly is typically enclosed by a cover plate 44. As an alternate embodiment the disk drive 42 may be constructed without a shield plate 42 wherein the plates provide a magnetic return path.

The roller bearing 30 allows the actuator arm 22 to pivot about the bearing block 26 and base plate 28 when the actuator arm 22 is rotated relative to the magnetic disk. The actuator arm 22 and roller bearing 30 are preferably constructed from a silicon carbide which is both hard and strong. The roller bearing 30 and bearing block are typically constructed as solid members which are able to withstand large shock loads. The entire height of the bearing block and roller bearing is such that the bearing assembly can be used in a hard disk drive which complies with the dimensional requirements of any of the PCMIA formats. The PCMCIA is an association that has promulgated a specification which list dimensions and other requirements for a standard electronic card. Each computer that conforms with the PCMCIA specification will contain slots that can receive a standardized card. With such a standard, electronic cards of one computer can be readily plugged into another computer, regardless of the model or make of the computers.

The PCMCIA standard includes three types of cards which each have varying thicknesses. A type I card is approximately 3.3 millimeters thick, a type II card is approximately 5.0 millimeters thick and a type III card is approximately 10.5 millimeters thick. The computer has a plurality of adjacent slots that are wide enough to receive a type II card. Both the type I and II cards occupy a single slot, while the type III card occupies two slots. Each computer slot contains a 68 pin connector that is typically mounted to a motherboard to provide an interconnect to the computer system. The PCMCIA standards were originally established for memory and/or logic cards including internal modem and facsimile boards. The present invention provides a actuator arm assembly that can conform to the PCMCIA type II card format.

While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.

Claims

What is claimed is:

1. A bearing assembly for an actuator arm assembly of a hard disk drive unit, comprising: a baseplate; a bearing block extending from said baseplate, said bearing block having a V-shaped slot that has a first apex; an actuator arm that has a roller bearing which extends into said V- shaped slot, said roller bearing further having a second apex which is contiguous with said first apex of said V-shaped slot; and, clamping means for clamping said actuator arm to said bearing block.

2. The bearing assembly as recited in claim 1, wherein said bearing block has a circular cross-section and said first apex is located at a center of said bearing block.

3. The bearing assembly as recited in claim 2, wherein said roller bearing has a triangular shape and extends from a bearing beam that has an arcuate surface in contact with said clamping means.

4. The bearing assembly as recited in claim 3, wherein said bearing block has a first radius that is approximately one-half a second radius measured from said center of said bearing block to said arcade surface of said support beam.

5. The bearing surface as recited in claim 3, wherein said clamping means is a C shaped clip that has a first arm in contact with said arcuate surface of said bearing beam and a second arm in contact with said bearing block.

6. The bearing surface as recited in claim 1, further comprising a magnet attached to said actuator arm and a coil attached to said baseplate.

7. A bearing assembly for an actuator arm assembly of a hard disk drive unit, comprising: a baseplate; a cylindrical bearing block extending from said baseplate, said bearing block having a V-shaped slot that has a first apex located at a center of said cylindrical bearing block; an actuator arm that has a triangular shaped roller bearing which extends from a bearing beam that has an arcuate surface, said triangular shaped roller bearing having a second apex which is contiguous with said first apex of said V-shaped slot; and, a clip which has a first arm in contact with said arcuate surface of said bearing beam and a second arm in contact with said bearing block, said clip being adapted to couple said triangular shaped roller bearing to said bearing block such that said actuator arm can rotate relative to said baseplate.

8. The bearing assembly as recited in claim 7, wherein said bearing block has a first radius that is approximately one-half a second radius measured from said center of said bearing block to said arcade surface of said support beam.

9. The bearing surface as recited in claim 8, further comprising a magnet attached to said actuator arm and a coil attached to said baseplate.

10. An actuator arm assembly for a hard disk drive unit, comprising; a baseplate; an actuator arm coupled to said baseplate and adapted to move relative to said baseplate, said actuator arm having a first end and a second opposite end; a magnetic head mounted to said first end of said actuator arm; a coil mounted to said baseplate; and, a magnet mounted to said second end of said actuator arm and operatively coupled to said coil.