Abstract:
A disk drive having an actuator-activated pumping mechanism is disclosed. The pumping mechanism creates a low pressure operating environment for the disk drive in order to enhance the performance of the drive at higher rotational operating speeds. Through the use of an engaging element, the actuator motor acts to drive a pumping element. This design does not use a separate electrical motor to evacuate the disk drive housing. Instead, the natural motion of the actuator provides the necessary power to drive the pumping element.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates in general to data access and storage devices, and in particular to disk drives. Still more particularly, the present invention relates to a system and method of activating a pumping system in a disk drive with the actuator. 
     2. Description of the Related Art 
     Disk drives, also called disk files, are information storage devices that use a rotatable disk with concentric data tracks containing the information, a head or transducer for reading and/or writing data onto the various tracks, and an actuator connected to a carrier for the head for moving the head to the desired track and maintaining it over the track centerline during read and write operations. The most common form of actuator is a rotary voice coil motor (VCM) actuator that moves the head carrier in a nonlinear, generally arcuate path across the disk. There are typically a number of disks mounted on a hub that is rotated by a disk drive motor, also called a spindle motor, and a number of head carriers connected to the actuator for accessing the surfaces of the disks. A housing supports the drive motor and head actuator, and surrounds the heads and disks to provide a substantially sealed environment. In conventional magnetic recording disk drives, the head carrier is an air-bearing slider that has an air-bearing surface (ABS) designed to enable the slider to “fly” or ride on a bearing of air above the disk surface when the disk is rotating at its operating speed. The slider is maintained next to the disk surface by a biasing force from a suspension that connects the slider to the actuator. The suspension is attached to a rigid arm connected to the actuator. 
     Contact start/stop (CSS) disk drives operate with the slider in contact with the disk surface during start and stop operation when there is insufficient disk rotational speed to maintain the air bearing. To minimize the effect of “stiction”, i.e., the static friction and adhesion forces between the very smooth disk surface and the slider, CSS disk drives often use a dedicated “landing zone” where the slider is parked when the drive is not operating. The landing zone is typically a specially textured, non-data region of the disk. 
     In contrast to CSS disk drives, “load/unload” disk drives address the stiction problem by mechanically unloading the slider from the disk when the power is turned off, and then loading the slider back to the disk when the disk has reached a speed sufficient to generate the air bearing. The loading and unloading is typically done by means of a ramp that contacts the suspension when the actuator is moved away from the data region of the disk. The slider is thus parked off the disk surface with the suspension supported in a recess of the ramp. Load/unload disk drives are more commonly used in laptop and notebook computers because the parking of the slider on the ramp away from the disk surface also provides some resistance to external shocks caused by moving or dropping the computer. 
     To improve the performance of disk drives, particularly the rate at which the recorded data can be accessed, it is desirable to rotate the disk at high rotational velocities. In addition, it is desirable to place the data tracks as close together as possible to maximize the data storage capacity. However, when conventional disk drives, such as commercially available 3.5 inch and 2.5 inch form factor drives, are rotated at high rotational velocities they consume excessive power and generate excessive heat in the disk drive housing. In addition, high speed disk rotation causes airflow-induced disk “flutter” and vibration of the suspension and/or arm, which makes it difficult for the read/write head to locate the proper data track. This is referred to as track misregistration (TMR). 
     The use of a hermetically sealed disk drive housing containing a gas other that air, such as helium, to reduce the effect of heat generation within the housing has been proposed, as described in U.S. Pat. No. 4,367,503 and Japanese published patent application JP8077527A. IBM Technical Disclosure Bulletin, Vol. 23, No. 9 (February 1981), describes a removable disk pack mounted on a drive apparatus that uses reduced air pressure around the rotating disks to reduce the effects of heat generation and air turbulence. Japanese published patent application JP7021752A describes a test apparatus that uses a vacuum pump to remove air from within the test chamber for the purpose of testing the head carrier-disk interface. Japanese published patent application JP 10222960A describes an optical CD-ROM drive with a vacuum pump for removing air to decrease air resistance and eliminate dust particles. 
     In another prior art example, U.S. Pat. No. 6,144,178, a system for reducing the operational pressure inside a disk drive assembly is disclosed. However, this design requires a dedicated electrical motor, which implies the use of expensive additional parts in the disk drive. Moreover, the motor size or volume is severely constrained, which in turn constrains the amount of energy that can be safely dissipated. Consequently, the pumping rate is relatively slow. Thus, an improved system and method for reducing the operational pressure inside a disk drive assembly at high rotational velocities without consuming excessive power and without generating disk flutter or vibration of the suspension or arm would be desirable. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the present invention, a disk drive having an actuator-activated pumping mechanism is disclosed. The pumping mechanism creates a low pressure operating environment for the disk drive in order to enhance the performance of the drive. Through the use of an engaging element, the actuator motor acts to drive a pumping element. This design does not use a separate electrical motor to evacuate the disk drive housing. Instead, the natural motion of the actuator provides the necessary power to drive the pumping element. 
     The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments. 
     FIG. 1 is a plan view of a disk drive constructed in accordance with the invention. 
     FIG. 2 is an enlarged plan view of the disk drive of FIG. 1 showing the actuator in a first pumping position. 
     FIG. 3 is an enlarged plan view of the disk drive of FIG. 1 showing the actuator in a second pumping position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a schematic drawing of one embodiment of an information storage system comprising a magnetic hard disk file or drive  11  for a computer system is shown. Drive  11  has a sealed outer housing or base  13  containing a plurality of stacked, parallel magnetic disks  15  (one shown) which are closely spaced apart. Disks  15  are rotated by a spindle motor located therebelow about a central drive hub  17 . An actuator  21  comprises a plurality of stacked, parallel actuator arms  25  (one shown) in the form of a comb that is pivotally mounted to base  13  about a pivot assembly  23 . A controller  19  is also mounted to base  13  for controlling the selective movement of the comb of arms  25  relative to disks  15 , and for other operational functions of drive  11 . 
     In the embodiment shown, each arm  25  has extending from it a pair of parallel, cantilevered load beams or suspensions  27 , and at least one magnetic read/write transducer or head  29  mounted on a slider secured to a flexure that is flexibly mounted to each suspension  27 . The read/write heads  29  magnetically read data from and/or magnetically write data to disks  15 . The level of integration called head gimbal assembly is head  29  mounted on suspension  27 . Suspensions  27  have a spring-like quality which biases or maintains them in parallel relationship relative to one another. 
     A voice coil motor  31  housed within a conventional voice coil motor magnet assembly (not shown) is also mounted to the arms  25  opposite head gimbal assemblies  29 . Movement of an actuator driver  33  (indicated by arrow  35 ) moves head gimbal assemblies  29  radially across tracks on the disks  15  until the heads on assemblies  29  settle on the target tracks. A crash stop  37  limits the pivotal range of motion of head  29  on actuator  27  in the radially inward (toward hub  17 ) direction. The head gimbal assemblies  29  operate in a conventional manner and always move in unison with one another, unless drive  11  uses a split actuator (not shown) wherein the arms move independently of one another. Drive  11  is also equipped with a pump assembly  41  that will be described in further detail below. 
     Referring now to FIGS. 2 and 3, enlarged views of actuator  21  and pump assembly  41  are shown. In the embodiment shown, pump assembly  41  comprises a pump housing  43  having an internal chamber or cylinder  45  with a sealed backstop  47  on one end (right side of FIGS.  2  and  3 ). A fluid conduit  48  extends between pump assembly  41  and an exterior of drive  11  for releasing pressure to the ambient surroundings and for evacuating drive  11 . A small piston  49  is located in cylinder  45  for reciprocal axial motion therein. A compression spring  51  is located between backstop  47  and piston  49  for biasing piston  49  away from backstop  47  (to the left in FIGS.  2  and  3 ). In this version, a short piston rod  53  extends from piston  49  opposite spring  51 . Piston rod  53  passes through a small hole in housing  43  to an exterior thereof adjacent to voice coil motor  31  of actuator  21 . 
     In operation, pump assembly  41  is used to partially evacuate the interior atmosphere of sealed drive  11  in order to lower its operating pressure. Pump assembly  41  is activated by the simple oscillatory pivot motion of actuator  21 , rather than by a dedicated motor as is required in the prior art. When actuator  21  rotates in a counterclockwise direction (FIG.  2 ), voice coil motor  31  moves toward crash stop  37  and away from pump assembly  41 . In this way, voice coil motor  31  releases piston rod  53 , thereby allowing piston  49  to move the left via expanding spring  51 . 
     When actuator  21  rotates back in the clockwise direction (FIG.  3 ), voice coil motor  31  moves toward pump assembly  41  to push piston rod  53  and piston  49  to the right and compress spring  51 . Such motion lowers the pressure of drive  11  incrementally via conduit  48 . When this process is repeated by oscillating actuator  25  between the two positions of FIGS. 2 and 3, drive  11  is partially evacuated to lower the operating pressure thereof. This process may be employed as necessary to maintain an adequate operating environment. Ideally, this process is used at start-up of drive  11 . 
     Drive  11  is also provided with a pressure sensor  55  (FIG. 1) that is monitored by controller  19 . When the pressure in drive  11  is below a threshold operating requirement, the pressure-reducing sequence can be initiated to lower the operating pressure of drive  11  to an acceptable level. Alternatively, pump assembly  41  may be activated at regular intervals, such as once per day or once per week, to maintain a proper operating pressure in drive  11 . Note that the illustrative pivotal range of motion of actuator  21  in the clockwise direction of FIG. 3, for example, may be greater than that shown in order to perform its normal reading and writing functions. In one version, when actuator  21  is rotated in the counterclockwise direction (FIG.  2 ), voice coil motor  31  may not always be in physical contact with piston rod  53 , which then remains in the extended position due to the bias of spring  51 . 
     The present invention has several advantages over other prior art configurations. Disk drive assemblies that are equipped to generate pumping action via their voice coil motor are able to reduce the number of parts and the cost required to accomplish the same objective in the prior art. The present design also offers an increase in both power and pumping rate over other designs. Moreover, the necessary reduction in pressure can be achieved while the drive is accelerating up to its operational speed. As a result, the read/write heads are able to immediately perform their functions when loaded onto a disk. In addition, the power required for the pumping action is reduced very quickly, and the increased pump rate can have a less negative effect on acoustics. 
     While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.