Patent Publication Number: US-2002012279-A1

Title: Low pressure operation for reduced excitation in a disc drive

Description:
RELATED APPLICATION  
       [0001] This application claims the benefit of U.S. Provisional Application Serial No. 60/202,891 filed May 10, 2000 under 35 U.S.C. 119(e).  
       FIELD OF THE INVENTION  
       [0002] The present invention relates to the field of mass storage devices. More particularly, this invention relates to an apparatus and method for reducing the pressure within a disc drive enclosure.  
       BACKGROUND OF THE INVENTION  
       [0003] One key component of any computer system is a device to store data. Computer systems have many different places where data can be stored. One common place for storing massive amounts of data in a computer system is on a disc drive. The most basic parts of a disc drive are an information storage disc that is rotated, an actuator that moves a transducer to various locations over the disc, and electrical circuitry that is used to write and read data to and from the disc. The disc drive also includes circuitry for encoding data so that it can be successfully retrieved and written to the disc surface. A microprocessor controls most of the operations of the disc drive as well as passing the data back to the requesting computer and taking data from a requesting computer for storing to the disc.  
       [0004] The transducer is typically placed on a small ceramic block, also referred to as a slider, that is aerodynamically designed so that it flies over the disc. The slider is passed over the disc in a transducing relationship with the disc. Most sliders have an air-bearing surface (“ABS”) which includes rails and a cavity between the rails. When the disc rotates, air is squeezed between the rails and the disc surface causing pressure, which forces the head away from the disc. At the same time, the air rushing past the cavity or depression in the air bearing surface produces a “negative pressure” area. The “negative pressure” or suction counteracts the pressure produced at the rails. The slider is also attached to a load spring which produces a force on the slider directed toward the disc surface. The various forces equilibrate so the slider flies over the surface of the disc at a particular desired fly height. The fly height is the distance between the disc surface and the transducing head, which is typically the thickness of the air lubrication film. This film eliminates the friction and resulting wear that would occur if the transducing head and disc were in mechanical contact during disc rotation. In some disc drives, the slider passes through a layer of lubricant rather than flying over the surface of the disc.  
       [0005] Information representative of data is stored on the surface of the storage disc. Disc drive systems read and write information stored on tracks on storage discs. Transducers, in the form of read/write heads attached to the sliders, located on both sides of the storage disc, read and write information on the storage discs when the transducers are accurately positioned over one of the designated tracks on the surface of the storage disc. The transducer is also said to be moved to a target track. As the storage disc spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the storage disc. Similarly, reading data on a storage disc is accomplished by positioning the read/write head above a target track and reading the stored material on the storage disc. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track.  
       [0006] The methods for positioning the transducers can generally be grouped into two categories. Disc drives with linear actuators move the transducer linearly generally along a radial line to position the transducers over the various tracks on the information storage disc. Disc drives also have rotary actuators which are mounted to the base of the disc drive for accurate movement of the transducers across the tracks of the information storage disc. Rotary actuators position transducers by rotationally moving them to a specified location on an information recording disc. A rotary actuator positions the transducer quickly and precisely. For example, the rotary actuator moves the transducer at hundreds of inches per second during a long seek. The rotary actuator undergoes hundreds of G&#39;s of force when moved.  
       [0007] The actuator is rotatably attached to a shaft via a bearing cartridge which generally includes one or more sets of ball bearings. The shaft is attached to the base and may be attached to the top cover of the disc drive. A yoke is attached to the actuator. The voice coil is attached to the yoke at one end of the rotary actuator. The voice coil is part of a voice coil motor which is used to rotate the actuator and the attached transducer or transducers. A permanent magnet is attached to the base and cover of the disc drive. The voice coil motor which drives the rotary actuator comprises the voice coil and the permanent magnet. The voice coil is attached to the rotary actuator and the permanent magnet is fixed on the base. A yoke is generally used to attach the permanent magnet to the base and to direct the flux of the permanent magnet. Since the voice coil sandwiched between the magnet and yoke assembly is subjected to magnetic fields, electricity can be applied to the voice coil to drive it so as to position the transducers at a target track.  
       [0008] One problem associated with current disc drive designs is windage induced excitation or vibration. Quick and precise positioning of the transducer requires the reduction or minimization of the vibration or excitation of the structural members within the magnetic disc drive apparatus. One source of vibration or excitation of the structural members is caused by windage. Windage is air movement caused by rotating the disc or discs within a disc drive. Currently, discs are rotated at speeds of 5400 to 15,000 revolutions per minute. Higher speeds are contemplated in future drives. These higher speeds would result in more windage within a given environment in disc drive enclosure.  
       [0009] Another problem associated with windage and higher rotational speeds is that rotating a disc or discs within a disc drive require larger and larger amounts of power. Reducing the amount of power consumed in a disc drive is a constant design goal of disc drive manufacturers. Reducing or minimizing power consumption is absolutely critical for disc drives used in portable computers. By reducing the power consumption of one of the key components, namely the disc drive, the portable computer can run on battery power for an extra amount of time. In addition, desk top computers also seek to reduce the amount of power used. Some governments even have requirements in the specifications of the computing equipment to be purchased which limits the amount of power consumption.  
       [0010] What is needed is a disc drive which has is less susceptible to vibrational or excitation due to windage. This will improve settling characteristics after a seek from a first track on the disc to a target track on the disc and will improve track following operations of the disc drive. This will also improve the seeking process. In other words, there is a need for a disc drive that has less relative motion between the actuator assembly and the disc while under any type of servo control that requires corrections to be implemented with the voice coil motor. There is also a need for a disc drive which uses less power. Also needed is a disc drive device that can be assembled using current assembly techniques and which does not add cost. Further, there is a need for a solution to reduce windage and reduce power which fits within set form factors for disc drives.  
       SUMMARY OF THE INVENTION  
       [0011] A disc drive includes a base, a spindle rotatably attached to the base, and at least one disc attached to the spindle. A cover is attached to the base. The cover and the base form a disc enclosure for the spindle and the disc or discs. A pump mechanism is located within the disc enclosure. The pump mechanism reduces the pressure within the disc enclosure. A valve is located in one of the cover and the base and allows a gas or fluid to move out of the disc enclosure. In one embodiment, the pump mechanism is integral to the spindle. The spindle includes a plurality of impeller blades adapted to direct a gas or fluid toward the valve. The valve is located in the base of the disc drive proximate the plurality of impeller blades of the spindle. In another embodiment, the impeller blades are replaced with a plurality of scales adapted to direct a gas or fluid toward the valve.  
       [0012] The valve includes a ball, and a seat for receiving the ball such that when the ball is received within the seat a seal is formed. The valve further includes an elastomeric member for placing a force on the ball while it is seated within the seat. The size of the elastomeric member is selected to place a select amount of force on the ball seated within the seat. In some embodiments, a spring places a force on the ball while it is seated within the seat. The spring has a force constant so that when the spring is compressed a selected distance a selected force is placed on the ball while it is seated within the seat. A portion of the ball is in fluid communication with the interior of the disc enclosure and the spring is selected so that the pressure on the ball in fluid communication with the interior of the disc enclosure produces a force allowing the ball to move away from the seat. The spring has a first end and a second end and one of these ends impinges on the ball and the other of these ends impinges on a fixed structure. In some embodiments, the fixed structure is attached to the base, and in other embodiments the fixed structure is attached to a printed circuit board. In some embodiments, the pump mechanism is made of silicon using micro-machining processes, such as a micro-electromechanical system or nano-electromechanical system.  
       [0013] A disc drive includes a base, a spindle rotatably attached to the base, and at least one disc attached to the spindle. The disc drive also includes a cover attached to the base. The cover and the base form a disc enclosure for the spindle and the disc or discs. The disc drive also includes a micro-machined pump mechanism for reducing the pressure within the disc enclosure, and a valve located in one of the cover and the base. The valve allows a gas or fluid to flow out of the disc enclosure. The micro-machined pump mechanism is made of silicon. The disc drive may also include a microprocessor. The micro-machined pump mechanism may be under control of the microprocessor.  
       [0014] Advantageously, the disc drive of the present invention is less susceptible to vibrational or excitation due to windage. Since the mechanical structures within the disc drive are less susceptible to excitation due to windage, the settling characteristics after a seek from a first track on the disc to a target track on the disc are improved. This also enhances the seeking process since there is less relative motion between the actuator assembly and the disc while under servo control. Since the excitations are lessened, the amount of servo corrections resulting from such vibration or excitation are also less. The disc drive also uses less power since the windage is less when the pressure within the disc drive is less. In other words, the low pressure environment translates into less drag on the disc or discs within the disc drive. The disc drive device that can be assembled using current assembly techniques and adds little, if any, additional cost. The present invention requires no additional sensors or pumps. In addition, the solution of the present invention for reducing windage and reducing power consumption fits within set form factors for disc drives. For example, an external pump is not needed to reduce the pressure within the disc drive. Still another advantage is that the disc drive is more reliable. The disc drive is more reliable since there is less excitation of the components, and is also more reliable since the reduced pressure operation is not dependent on external components. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIG. 1 is an exploded view of a disc drive with a multiple disc stack.  
     [0016]FIG. 2 is a schematic representation of an embodiment of a hard disc drive incorporating an interior pump.  
     [0017]FIG. 3 is a bottom view of the spindle or hub assembly  133 .  
     [0018]FIG. 4 is a representation of a ball valve used with the interior pump.  
     [0019]FIG. 5 is a schematic representation of another embodiment of a hard disc drive incorporating an interior pump.  
     [0020]FIG. 6 is a schematic representation of the embodiment of a hard disc drive incorporating an interior pump of FIG. 5 showing the disc enclosure.  
     [0021]FIG. 7 is a bottom view of the injection molded portion which is attached to the spindle hub assembly.  
     [0022]FIG. 8 is a schematic representation of yet another embodiment of a hard disc drive incorporating an interior pump.  
     [0023]FIG. 9 is a schematic representation of an embodiment of a hard disc drive incorporating an exterior pump.  
     [0024]FIG. 10 is a schematic representation of yet another embodiment of this invention.  
     [0025]FIG. 11 is a schematic view of a computer system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0026] In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.  
     [0027] The invention described in this application is useful with all mechanical configurations of disc drives having either rotary or linear actuation. In addition, the invention is also useful in all types of disc drives including hard disc drives, zip drives, floppy disc drives and any other type of drives. FIG. 1 is an exploded view of one type of a disc drive  100  having a rotary actuator. The disc drive  100  includes a housing or base  112 , and a cover  114 . The base  112  and cover  114  form a disc enclosure. Rotatably attached to the base  112  on an actuator shaft  118  is an actuator assembly  120 . The actuator assembly  120  includes a comb-like structure  122  having a plurality of arms  123 . Attached to the separate arms  123  on the comb  122 , are load beams or load springs  124 . Load beams or load springs are also referred to as suspensions. Attached at the end of each load spring  124  is a slider  126  which carries a magnetic transducer  150 . The slider  126  with the transducer  150  form what is many times called the head. It should be noted that many sliders have one transducer  150  and that is what is shown in the figures. It should also be noted that this invention is equally applicable to sliders having more than one transducer, such as what is referred to as an MR or magneto resistive head in which one transducer  150  is generally used for reading and another is generally used for writing. On the end of the actuator arm assembly  120  opposite the load springs  124  and the sliders  126  is a voice coil  128 .  
     [0028] Attached within the base  112  is a first magnet  130  and a second magnet  131 . As shown in FIG. 1, the second magnet  131  is associated with the cover  114 . The first and second magnets  130 ,  131 , and the voice coil  128  are the key components of a voice coil motor which applies a force to the actuator assembly  120  to rotate it about the actuator shaft  118 . Also mounted to the base  112  is a spindle motor. The spindle motor includes a rotating portion called the spindle hub  133 . In this particular disc drive, the spindle motor is within the hub. In FIG. 1, a number of discs  134  are attached to the spindle hub  133 . In other disc drives a single disc or a different number of discs may be attached to the hub. The invention described herein is equally applicable to disc drives which have a plurality of discs as well as disc drives that have a single disc. The invention described herein is also equally applicable to disc drives with spindle motors which are within the hub  133  or under the hub.  
     [0029]FIG. 2 is a schematic representation of an embodiment of a hard disc drive  100  incorporating an interior pump. As shown in FIG. 2, the base or deck  112 , in combination with the cover  114 , form a disc enclosure  200 . The disc enclosure  200  is the interior environment formed inside the disc drive  100 . Inside the disc drive, as shown in FIG. 2, is the spindle hub  133 . The spindle hub  133  is shown without discs. Also not shown are the magnets  130 ,  131  and the actuator assembly  120 . These components are removed for the sake of clarity but would be within a disc drive  100  incorporating this invention. The spindle hub  133  includes a surface  210  positioned near the base or deck  112  of the disc drive  100  as well as a surface  230  upon which a deck disc  134  sits (see FIGS. 1 and 5). The hub  133  also includes a central annular portion  240 . The diameter of the annular portion  240  is slightly less than the inner diameter of a disc  134 . As a result, the disc or discs  134  fit over the annular portion  240  (see FIG. 1). In forming a disc stack, at least one or a plurality of discs  134  are placed onto the annular portion  240  of the hub  133 . The discs  134  are spaced apart from one another by ring spacers. Generally, the disc or discs are clamped to the annular portion  240  to form a disc stack with one or more discs in spaced relation with respect to one another (more clearly seen in FIGS. 1 and 5). The spindle hub  133  rotates on a pivot axis  250 . The pivot axis  250  generally includes a set of bearings which allow for the smooth rotation of the spindle hub  133  and attached discs (not shown in FIG. 2). It should be noted that the spacing between the base or deck  112  and the spindle hub  133 , as shown in FIG. 2, is exaggerated for the purpose of illustration. In other words, the surface  210  of the spindle hub  133  is generally more closely spaced to the base or deck  112  than illustrated in FIG. 2.  
     [0030] The base  112  includes an opening  260  between the disc enclosure  200  or the interior space of the disc drive  100  and the space exterior of the disc drive  100 . Positioned within the opening  260  is a ball valve  400 . The ball valve  400  allows for outward flow of a gas or fluid from the disc enclosure  200  or interior portion of the disc drive  100  to an area outside the disc drive  100 .  
     [0031]FIG. 3 is a bottom view of the disc drive  100  along line  33  in FIG. 2. FIG. 3 shows the opening  260  as well as the deck  112 . FIG. 3 also shows the bottom of the spindle hub  133 . Put another way, FIG. 3 shows the surface  210  of the spindle hub  133 . Surface  210  is the surface of the spindle hub  133  proximate or near the base or deck  112 . The direction of rotation of the spindle hub  133  is depicted by arrow  300 . The surface  210  of the spindle hub  133  includes a plurality of flutes or curved surfaces  310  which are used to move air within the disc enclosure  200  toward the center of the surface  210 . The center of the surface  210  is depicted by a circle carrying the reference numeral  212 . The flutes  310  act as fan blades. As the spindle hub  133  rotates in direction  300 , the flutes  310  move the air toward the center  212  of the surface  210  and build or form a high pressure area near the center  212  of the surface  210 . The high pressure area forces the ball valve  400  to open and expel gas from the disc enclosure or interior portion of the disc drive  100  to the outside environment. In this particular embodiment, the spindle hub  133  includes an integral pump in that the flutes  310  on the bottom surface or surface  210  of the spindle hub essentially form a turbo pump to force gas from the disc enclosure to the exterior of the disc drive. Of course, it should be noted that the positioning of the flutes  310  can be changed as well as the amount of curvature of the flutes can be changed in order to accommodate specific design parameters. For example, it may not be necessary to have quite as dramatic a flute  310  if the rotational speed of the spindle hub  133  is faster than in previous applications. Furthermore, flutes  310  do not necessarily have to be used. In some instances, the surface can be provided with fish scales. It should also be noted that other designs may be used to produce a high pressure area at or near the center  212  of the surface  210  of the spindle hub.  
     [0032]FIG. 4 is a representation of a ball valve  400  used in conjunction with the interior pump. The opening  260  is tapered. The larger portion of the opening  260  faces the exterior of the disc drive while the smaller portion of the tapered opening  260  is positioned at or near the interior surface of the disc drive  100 . The ball valve  400  includes a ball  410  and a spring  420 . The ball  410  is seated within the opening  260  so that a seal is formed between the ball  410  and the opening  260 . The spring  420  has one end attached to a fixed surface  430  and another end either attached to the ball  410  or impinging upon the ball  410 . The spring has a force constant which is selected to place a selected amount of force on the ball  410  as seated within the opening  260 . The spring and the amount of deflection is selected so that the ball valve  400  will open at or near a selected pressure within the disc drive or when the pressure at the opening  260  or proximate the ball valve  400  is at or near a selected level. When the pressure on the ball produces a force which is greater than the force placed upon the ball by the spring  420 , the ball  410  unseats itself from the side of the opening  260  and allows gas from the interior portion of the disc drive  100  to pass from the interior to the exterior. When the pressure on the ball  410  produces a force less than the force produced by the spring  420 , the spring  420  keeps the ball  410  seated within the opening  260 . As a result, when the pressure is less than the desired pressure within the disc drive, the ball remains seated within the opening  260  and does not allow gas exterior of the disc drive to pass into the interior portion or disc enclosure  200 . The ball valve  400  is self-regulating in that it opens at or near a selected pressure. The ball valve  400 , therefore, acts as a one-way fluid path. Also it should be noted that the spring  420  can be attached to any fixed surface  430 . For example, it is contemplated that a bar might be placed over the opening or the exterior portion of the opening  260  to which the spring  420  could attach. It is also contemplated that when the base or deck  112  is thin, an extra U-shaped portion could be added to the base  112  about the opening  260 . The spring  420  could then be added to the bottom portion of the U which would form the fixed surface  430 .  
     [0033]FIG. 5 is a schematic representation of another embodiment of a hard disc drive  100  incorporating an interior pump  550 . FIG. 5 is actually only a partial showing of the disc drive  100 . Specifically, FIG. 5 shows a portion of the base  112 , the hub  113 , the spindle shaft  533 , the bearing sets  560 ,  562 , which are used to attach the hub  133  to the spindle shaft  533 , and an internal motor  57  within the hub  133 . The base  112  includes a valve  500 . The valve  500  includes a ball  510 , a spring  520 , and an opening  540  which has a tapered portion  542  into which the ball  510  is seated by the spring  520 . The hub  133  includes a surface  210  which is positioned proximate or near the base  112 . Attached to the surface  210  is an injection-molded ring  550  which includes impeller blades  552 . The hub  133  also includes a seal  535 . The seal is a positive pressure seal such as a ferrofluid seal. The base  112  also includes an annular ring structure  580 . The annular ring structure produces an air gap  582  between the rotating hub  133  and the annular ring  580 . The air gap is spaced or is used to control the air volume and feed for incoming air. The air gap  582  is essentially the inlet to the pump. Attached to the surface  210  of the hub  133  is a molded annular ring which includes pump fins or impellers  552 . The molded annular ring  550  is formed and then attached to the surface  210  using a suitable adhesive. The ring  550  is made by injection molding. Advantageously, the ring  550  and the attached impellers  552  can be easily added to the surface  210  of the hub  133 . The valve  500  is used to regulate the desired pressure within the disc drive enclosure  200 . The valve  500  is essentially the outlet of the pump formed by the hub  133  and the injection molded ring attached to the bottom surface or surface  210  of the spindle  133 . The disc drive may also be provided with a pressure chamber  590 , which is shown in dotted lines in FIG. 5. The pressure chamber  590  is where the air is pumped out or pumped into from the valve  500 .  
     [0034] The air pump formed by the spindle  133  and the annular ring  550  with the impellers  552  is preferably attached to the base of the spindle hub  133 , as shown in FIG. 5. As mentioned previously, the molded injection annular ring is attached to the outer spindle hub or surface  210  by an adhesive or other means. The outer portion of the hub and specifically the surface  210  to which the annular injection molded part  550  is attached can also be referred to as the runner of the pump that is formed. The pump impellers are designed to impart of velocity to the fluid or air relative to the vein causing a change in pressure at the inlet of the turban or pump which is formed. The valve  500 , which is shown or detailed in FIG. 5 as well as FIG. 6, is needed to prevent backflow within the disc enclosure  200 .  
     [0035]FIG. 6 is a schematic representation of the embodiment of the hard disc drive incorporating the interior pump of FIG. 5 and showing the entire disc enclosure  200 . The pump formed in FIG. 5 includes the annular ring and its impellers  552  as well as the valve  500 , the hub  133  and the spindle  533  upon which the hub  133  rotates. The disc enclosure is formed by the base  112  and the cover  114 . The disc enclosure  200  encloses the hub  133  and attached discs or disc  134  (shown in FIG. 1). The reduction in pressure within the disc drive enclosure  200  is regulated with a pressure regulator  600 , which includes a ball  610  and a spring system  620 . The regulator  600  is generally integrated with an external air filter.  
     [0036]FIG. 7 is a bottom view of the injected molded portion or annular ring  500 , which is attached to surface  210  of the spindle or hub assembly  133 . The annular ring  550  includes impellers  552 . As shown in FIG. 7, the impellers  552  are of a cup-like design. Other designs, such as a herringbone, a raleigh or other design can be used to expel the air out of the disc drive enclosure  200 . As mentioned previously, the annular ring  550  may be made by injection molding. The annular ring and its impellers  552  are then attached to surface  210  of the hub assembly  133 .  
     [0037] Advantageously, using a mold injected pump or annular ring  550  with impellers is a low-cost approach and allows use of the existing spindle hub  133 . Although the spindle  133  is shown as riding on ball bearings, this approach is equally effective on a spindle hub  133 , which uses a fluid bearing.  
     [0038]FIG. 8 is a schematic representation of another embodiment of the hard disc drive incorporating an interior pump. FIG. 5 shows a spindle hub  133  populated with a plurality of discs  134  to form a disc stack. Positioned interior to the disc enclosure is an internal pump which moves gas molecules from the interior surface of the disc drive  100  to the exterior of the disc drive. In other words, the pump  800  moves molecules of gas from the disc enclosure  200  formed by the base  112  and the cover  114  to points outside the disc drive  100 . The pump  800  can be any type of pump, including pumps made from micro-electromechanical technology or from nanotechnology such as micro-machined from silicone. It should be noted that the interior pump  800  can be placed anywhere within the disc enclosure  200  including various spots on the base or deck  112  as well as various spots on the cover  114 .  
     [0039]FIG. 9 is a schematic representation of an embodiment of a hard disc drive  100  incorporating an exterior pump  900 . The exterior pump  900  is placed on the outside of the base  112  or on the outside of the cover  114 . The external pump  900  must be small enough so as not to interfere with the form factor associated with the disc drive  100 . Changing the form factor would require massive changes in the openings used for the various applications of these disc drives. In other words, the openings in bays of computers would have to be changed as well as openings used for other storage devices. Changing the form factor can be devastating to a disc drive and can actually result in nonacceptance of the disc drive in the marketplace. Therefore, it is extremely important that the end product fit within the form factor and fit within the base provided for the various applications in industry. As a result, the external pump  600  must be very, very small and must be able to be incorporated easily within the form factor. As a result, the external pump must be small and must be something such as made by nanotechnology.  
     [0040]FIG. 10 shows the use of another ball valve on a thin sidewall of a base  112 . The ball includes an angled or chamfered opening and a U-shaped bracket  1030 . A ball  1010  fits within the opening. A spring is attached between the ball  1010  and the bracket  1030 . The bracket  1030  provides the fixed surface to which the spring is attached. In the alternative, the spring  1020  may merely contact the ball  1010  rather than being connected to it. It should also be noted that the ball valve  1000  or the ball valve  400  can be located at various positions around the disc drive  100 .  
     [0041] Advantageously, the disc drive of the present invention is less susceptible to vibrational or excitation due to windage. Since the mechanical structures within the disc drive are less susceptible to excitation due to windage, the settling characteristics after a seek from a first track on the disc to a target track on the disc are improved. This also enhances the seeking process since there is less relative motion between the actuator assembly and the disc while under servo control. Since the excitations are lessened, the amount of servo corrections resulting from such vibration or excitation are also less. The disc drive also uses less power since the windage is less when the pressure within the disc drive is less. In other words, the low pressure environment translates into less drag on the disc or discs within the disc drive. The disc drive device that can be assembled using current assembly techniques and adds little, if any, additional cost. The present invention requires no additional sensors or pumps. In addition, the solution of the present invention for reducing windage and reducing power consumption fits within set form factors for disc drives. For example, an external pump is not needed to reduce the pressure within the disc drive. Still another advantage is enhanced reliability. The disc drive is more reliable since there is less excitation of the components and also more reliable since the reduced pressure operation is not dependent on external components.  
     [0042]FIG. 11 is a schematic view of a computer system. Advantageously, the invention is well-suited for use in a computer system  2000 . The computer system  2000  may also be called an electronic system or an information handling system and includes a central processing unit, a memory and a system bus. The information handling system includes a central processing unit  2004 , a random access memory  2032 , and a system bus  2030  for communicatively coupling the central processing unit  2004  and the random access memory  2032 . The information handling system  2002  may also include an input/output bus  2010  and several devices peripheral devices, such as  2012 ,  2014 ,  2016 ,  2018 ,  2020 , and  2022  may be attached to the input output bus  2010 . Peripheral devices may include hard disc drives, magneto optical drives, floppy disc drives, monitors, keyboards and other such peripherals.  
     [0043] Conclusion  
     [0044] In conclusion, a disc drive  100  includes a base  112 , a spindle  133  rotatably attached to the base  112 , and at least one disc  134  attached to the spindle  133 . A cover  114  is attached to the base  112 . The cover and the base form a disc enclosure  200  for the spindle  133  and the disc  134  or discs  134 . A pump mechanism  210  is located within the disc enclosure  200 . The pump mechanism  210  reduces the pressure within the disc enclosure  200 . A valve  400  is located in one of the cover  114  and the base  112  and allows a gas or fluid to move out of the disc enclosure  200 . In one embodiment, the pump mechanism  210  is integral to the spindle  133 . The spindle  133  includes a plurality of impeller blades  310  adapted to direct a gas or fluid toward the valve  400 . The valve  400  is located in the base  112  of the disc drive  100  proximate the plurality of impeller blades  310  of the spindle  133 . In another embodiment, the impeller blades  310  are replaced with a plurality of scales adapted to direct a gas or fluid toward the valve  400 . The valve includes a ball  410 ,  1010 , and a seat for receiving the ball such that when the ball  410 ,  1010  is received within the seat a seal is formed. The valve  400 ,  1000  further includes an elastomeric member  420 ,  1020  for placing a force on the ball  410 ,  1010  while it is seated within the seat. The size of the elastomeric member  420 ,  1010  is selected to place a select amount of force on the ball  410 ,  1010  seated within the seat. In some embodiments, a spring  420 ,  1020  places a force on the ball  410 ,  1010  while it is seated within the seat. The spring  420 ,  1020  has a force constant so that when the spring  420 ,  1020  is compressed a selected distance a selected force is placed on the ball  410 ,  1010  while it is seated within the seat. A portion of the ball  410 ,  1010  is in fluid communication with the interior of the disc enclosure  200  and the spring is selected so that the pressure on the ball in fluid communication with the interior of the disc enclosure  200  produces a force allowing the ball  410 ,  1010  to move away from the seat. The spring  420 ,  1020  has a first end and a second end and one of these ends impinges on the ball and the other of these ends impinges on a fixed structure. In some embodiments, the fixed structure is attached to the base  112 , and in other embodiments the fixed structure is attached to a printed circuit board. In some embodiments, the pump mechanism is made of silicon.  
     [0045] A disc drive  100  includes a base  112 , a spindle  133  rotatably attached to the base  112 , and at least one disc  134  attached to the spindle  133 . The disc drive  100  also includes a cover  114  attached to the base  112 . The cover  114  and the base  112  form a disc enclosure  200  for the spindle  133  and the disc  134  or discs  134 . The disc drive  100  also includes a micro-machined pump mechanism for reducing the pressure within the disc enclosure  200 , and a valve  400 ,  1000  located in one of the cover  114  and the base  112 . The valve  400 ,  1000  allows a gas or fluid to flow out of the disc enclosure  200 . The micro-machined pump mechanism is made of silicon. The disc drive  100  may also include a microprocessor  2000 . The micro-machined pump mechanism may be under control of the microprocessor.  
     [0046] Most generally, a disc drive  100  includes a base  112 , a spindle  133  rotatably attached to the base  112 , and at least one disc  134  attached to the spindle  133 . A cover  114  is attached to the base  112 . The cover  114  and the base  112  form a disc enclosure  200  for the spindle  133  and the at least one disc  134 . The disc drive  100  also includes a mechanism for reducing the pressure within the disc enclosure.  
     [0047] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the fall scope of equivalents to which such claims are entitled.