Abstract:
A system and method for decreasing power consumption of hard disk drives through use of an external atmosphere of low density gas, such as helium, is described. An environment container reasonably resistant to diffusion and leakage of helium (container) is erected around an existing hard disk array or server, wherein a helium mixture is pumped into the container. The helium mixture within the container is maintained at a specified concentration via proper tubing and valves which may be manually or automatically controlled. The actual concentration need not be very pure in order to achieve reduced drag over the disks in each of the hard disk drives, thereby achieving reduced power consumption. The environment container is stand alone from the hard disk drives used such that an altered hard disk apparatus is unnecessary.

Description:
CLAIM FOR PRIORITY 
     The present invention claims priority to U.S. provisional patent application No. 61/431,022, filed on Jan. 9, 2011, by the inventor of the same name. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of electronic data storage and hard disk drive performance. The present invention more particularly relates to creating an atmosphere of low density gasses such as helium or helium mixtures to lower the power consumption of the drive or drives. 
     BACKGROUND OF THE INVENTION 
     Presently many organizations have a need for storing large quantities of data, to address this need, organizations will acquire massive disk drive arrays which each require a substantial amount of power to operate. Due to this, these organizations amass considerably large power costs. 
     In general, the majority of hard disk drives (HDD) are operated in a standard air (nitrogen, oxygen and water vapor mixture) atmosphere. Spinning disks in HDDs at high RPMs against the friction of an air atmosphere is what drives power costs and is largely inefficient. By running the HDD in an atmosphere which is less dense, such as an atmosphere composed of helium or a helium mixture, friction on the disk is reduced thereby causing the disk to require less power in order to spin at a similar rate. 
     In using a lower density atmosphere to reduce power costs, maintaining helium or a helium mixture inside the drive rather than a standard air mixture at a reasonable cost can pose additional problems. If the HDD is to be sealed, such that it maintains its own atmosphere, the drive will be prone to pressure differences between inside and outside the drive which produces mechanical stress that requires a more robust mechanical design. An additional problem arises when preventing leaking of internal helium during the operating life of the HDD (5 years). Special metal seals or welding have to be used to seal the drive properly. 
     Due to this all drives contain a breather hole which equalizes pressure inside and outside of the drive. However, a breather hole allows gas exchange and the helium would diffuse out after a relatively short period. Prior art has addressed this problem by welding the drive shut or adding metal seals. Additionally to withstand the potential pressure differences between inside and outside of the drive, prior art has mechanically reinforced the drive case in order to avoid warping of the critical precision drive mechanics. However, these prior techniques all call for heavy modification of production lines. 
     Accordingly, there is a need for an improved system that can effectively supply a HDD with a low density gas, such as helium, during use at low cost involving little to no changes to present production lines. The present invention provides a solution to this and other problems, and offers other advantages over the prior art. 
     BRIEF SUMMARY OF INVENTION 
     This and other objects of the present invention are made obvious in light of this disclosure, wherein methods and systems for maintaining a helium mixture environment within a hard disk drive (HDD) are described. 
     According to a first aspect of the system of the present invention, an external environment container reasonably resistant to diffusion and leakage of helium (container) is erected around a hard disk array or server, wherein a helium mixture is pumped into the container. The helium mixture and uniformity within the container is maintained at a specified concentration via proper tubing, fans, heat sinks and valves which may be manually or automatically controlled. Before being placed in the container, the HDDs in the array tower will be acclimated to a low density environment with separate helium filled enclosures and equalize via a standard breather hole that all commercial drives posses; thereby filling with a certain concentration of helium which closely matches the helium mixture in the container. The actual concentration of helium need not be very pure in order to achieve reduced drag over the disks in each of the HDDs, thereby achieving reduced power consumption. 
     According to a first preferred embodiment of the method of invention, the container begins full of air. A helium mixture is injected into the container, as pressure builds inside the container an over pressure valve is opened preferably at the base of the container allowing gas to escape easily. The container, being reasonably sealed, does not allow a significant amount of ambient air to enter, thus eventually all that remains within the container is a helium mixture. The helium mixture can be set for a constant or intermittent flow. The pre-acclimated hard drive array is then placed in the container, which will lose some helium mixture, and take on some air in the process. The container is sealed and the helium mixture flushes out the air over time thereby maintaining the helium mixture atmosphere. 
     INCORPORATION BY REFERENCE 
     All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference in their entirety and for all purposes to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. 
     Such incorporations include U.S. Pat. No. 6,785,089 (Inventors: Bernett, et al.; Issued on Aug. 31, 2004), titled “Disc Drive Gas Supply System”; U.S. Pat. No. 6,144,178 (Inventors: Hirano, et al.; Issued on Nov. 7, 2000), titled “Disk Drive With Controlled Reduced Internal Pressure”; U.S. Pat. No. 7,218,473 (Inventors: Bernett, et al.; Issued on May 15, 2007), titled “Two-Stage Sealing Of Data Storage Assembly Housing To Retain A Low Density Atmosphere”; U.S. Pat. No. 7,796,356 (Inventors: Fowler, et al.; Issued on Sep. 14, 2010), titled “Head Integrated Touchdown Sensor For Hard Disk Drives”; and U.S. Pat. No. 7,800,858 (Inventors: Bajikar, et al.; Issued on Feb. 21, 2010), titled “Differential Head Integrated Touchdown Sensors For Hard Disk Drives”. 
     The publications discussed or mentioned herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Furthermore, the dates of publication provided herein may differ from the actual publication dates which may need to be independently confirmed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings in which: 
         FIG. 1  is a simplified block diagram of a standard commercial hard disk drive, in accordance with an embodiment of the subject invention; 
         FIG. 2  is a an isometric block diagram of the invented external environmental system containing one or more disk drives; 
         FIG. 3  is a cross section of an alternate embodiment of a gas inlet; 
         FIG. 3A  is an alternate embodiment of a gas inlet system. 
         FIG. 4  is a flow chart of a preferred method of operations for the environmental system of  FIG. 2 ; 
         FIG. 5  is a block diagram of the apparatus involved in with preemptive acclimation of a hard disk drive; 
         FIG. 6  is a flow chart of the process involved with preemptive acclimation of a hard disk drive using the apparatus of  FIG. 5 ; 
         FIG. 7  shows a modified hard disk drive which could acclimate to a new environment more quickly than a standard drive; 
         FIG. 8  shows side view of a sample flying height of a head in a disk drive; 
         FIG. 9  is a plurality of invented environmental systems configured in series; and 
         FIG. 10  is a process taken by a flying height monitor of the head of a disk drive. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that this invention is not limited to particular aspects of the present invention described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. 
     Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as the recited order of events. 
     Where a range of values is provided herein, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits ranges excluding either or both of those included limits are also included in the invention. 
     Unless expressly defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the methods and materials are now described. 
     It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. 
     The term, “helium mixture” is to be expressly defined for the purposes of this disclosure as any of the following: pure atomic helium, crude helium, and an air/helium mixture or gas/helium mixture composed of at least 50% helium by volume which can also contain typical environmental gas contaminants like moisture, carbon dioxide, sulfur compounds, and heavier hydrocarbons as also found in crude helium. 
     Referring now to  FIG. 1 , a block diagram of a hard disk drive (Hereafter “HDD”)  2 . Standard commercial HDDs  2  presently all include at least one disk  4 , each with a matching head  6  poised on an arm controlled by an actuator  8 . These components are housed within a casing  10  which is effectively enclosed except a small breather hole  12  on the surface which allows for gas exchange inside and outside of HDD  2  to avoid pressure differences. The breather hole  12  contains a particle filter  14  to keep inflow gas clean. 
     Referring now to  FIG. 2 , a diagram of the invented external environmental system (hereafter “environmental system”)  16 . The environmental system  16  comprises a substantially air-tight, to completely air-tight container  18  with one or more hatches  20 , a gas inlet  22 , a heat exchanger  24 , an internal fan  25 , an electrical/data inlet  26 , a humidifier  28 , a gas supply  30 , an optional pressure sensor  32 , an optional gas mixture sensor  34  and an over pressure valve  36 . Placed inside the environmental system  16  would be one or more HDDs  2 , a HDD array  2   a  containing a plurality of HDDs  2  or server  3  which would comprise at least one HDD  2  and a controller. The substantially air-tight container (hereafter “container”)  18  would be constructed of sheet metal, plastic, plexiglass, or any other suitable material known in the art such that, when closed, the container  18 , is ideally sealed from ambient air transfer; however, marginal air seepage would still be acceptable. Actual construction and air seal strength would depend on cost of materials and many on-site variables. The container  18  need not be rigid in form, and could be constructed as a flexible bag in character as long as other specified characteristics were adhered to. The container  18  need not be vacuum tight and depending on material used or strength of the seals, some helium gas may diffuse out. Depending on the effectiveness the seal on the container  18 , it is foreseen that a completely air tight container  18  would not take on additional air, but would still lose helium mixture through diffusion. Helium mixture loss would be detected by either the optional pressure sensor  32  or a gas mixture sensor  34  and would then be replenished by the gas supply  30 . When the pressure within the container  18  becomes greater than that outside the environmental system  16 , an over pressure valve  36  would open, allowing gas to escape thus lowering the pressure inside the environmental system  16 . 
     The hatch  20  or the container  18  should be sealed with a rubber o-ring like device, a viton seal or any other suitable material known in the art such that when closed the seal prevents at least a substantial majority of air seepage. In order to maintain a helium mixture atmosphere within the container  18  while access to objects inside the environmental system  16  is required via the hatch  20 , the container  18  could be configured to maintain an internal pressure slightly above ambient atmosphere which would be established by the gas supply  30  and adding additional resistance to the over pressure valve  36 . The increased internal pressure would create an outward diffusion of gas for a short period until the pressure equalized such that limited ambient air would be able to enter the environmental system  16 . Additionally rather than a single hatch  20 , several smaller hatches  20  could be utilized one or more at a time in order to expose less open surface area when accessing the environmental system  16 . Alternatively or in addition to the aforementioned method, the environmental system  16  could be flushed with helium mixture from the gas supply  30  every time access was needed. 
     The electrical/data inlet  26  would be constructed such that it would accommodate the proposed contents of the environmental system  16 . The electrical/data inlet  26  would be substantially air tight similar to other apertures of the container  18 . In order to achieve this, an electrical and data BUS could be sealed into the wall of the container  18  or hatch(es)  20  and the HDD(s)  2  inside would connect to the internal end of the BUS and the external end would connect to a power source and the destination of the data stored in the HDD(s)  2 . 
     The heat exchanger  24  and internal fan  25  are used to maintain a specified temperature and uniform mixture of atmosphere inside the environmental system  16 . The heat exchanger  24  would take on one of many embodiments such that it would suitably dissipate heat created within the environmental system  16 . Gasses such as helium create less friction with the moving parts of a HDD  2  and thus will contribute to HDDs  2  generating less heat, further Helium changes temperature much less, requiring less heat dissipation. Refer to table 1; 
                                                   TABLE 1                   Helium   Air   Helium is                                Density (gm/cm{circumflex over ( )}3)   1.70E−04   1.20E−03   7× lower       Viscosity (μPoise)   194   182.7   similar       Thermal Conductivity   1.5   0.26   6× better       (W/cm-K)                    
Some suitable heat exchange methods would include systems similar to either an automobile radiators or a refrigerator. Another example of a suitable heat exchanger would be a cooling fin affixed to the surface of the container to increase said container&#39;s surface area, thereby supplying more material to absorb and subsequently dissipate heat to the exterior air. Other systems could also be feasible as long as they were able to adequately dissipate the heat generated by the chosen number of HDDs  2  to be kept within the environmental system  16 . The internal fan  25  would be affixed to either the top of the container  18  preferably facing down or the base of the container  18  preferably facing up. The optimal positioning on either surface would vary depending on specific construction of the container  18 . The purpose of the internal fan  25  would be to mix the lighter low density gas (helium mixture), with the heavier gasses present (such as air) which would otherwise gradually settle on the bottom of the container  18 . Natural convection caused by the heated drives will also contribute to the mixing.
 
     The humidifier  28  is used as a result that standard commercial HDDs  2  work better with some humidity. An environment of less than 10%rh can cause problems in HDDs  2  currently in production. As a result that bottled helium is generally very dry, a humidifier is necessary to keep humidity in a range favorable for HDD  2  running conditions, between 10%-60%rh. Future HDDs may function effectively without humidity; this would negate the need for a humidifier in the present invention. 
     Referring now to  FIG. 3 , a cross section of an alternate embodiment of a gas inlet  22   a . The alternate gas inlet  22   a  would include several valves  38 . The valves  38  could be controlled either manually or electronically. Each valve  38  would restrict access to one of three tubes  40 ,  42 ,  44  some of which being optional. The low density gas tube  40  would allow for the injection of a low density gas, such as a helium mixture, to the environmental system  16  via the gas supply  30 . The heavy gas tube  42  is optional and would allow for the flushing of a certain amount of a heavier gas, such as ambient air, and could be used as a cost saving measure, among other uses. The third tube, the humidity tube  44 , is optional and would replace the humidifier  26  while performing the same purpose. Referring to  FIG. 3A , a duel gas inlet system is shown. In this case the low density tube  40  would be placed at the top of the container  18  and a high density gas tube  42  would be preferably placed at the base of the container  18  such that these lines could be operated independently. Further the high density gas tube  42  would be affixed to a vacuum pump. The heavier air could be drained from the container  18  from the base while the lighter helium mixture was flushed in from the top. This alternate embodiment would alleviate much of the need for the internal fan  25 . 
     Referring now to  FIG. 4 , a flow chart of a preferred method of environmental system  16  operations which may be carried out in any order of the recited events which is logically possible. First, the empty container  18  is sealed and through the gas inlet  22 , a low density gas such as a helium mixture is flushed into the environmental system  16 . As gas pressure builds inside the environmental system  16  an over pressure valve  36  at the base of the container  18  releases internal gasses, including air. During the low density gas flush, no substantial amount of air is replaced within the container  18  and the environmental system gradually attains a low density atmosphere such as an atmosphere composed of helium mixture ( 402 ). Next, the HDDs  2  that will be placed within the environmental system  16  are acclimated to a low density environment ( 404 ). The HDDs  2  are then placed inside the environmental system  16  ( 406 ). After the environmental system  16  is sealed again, an additional low density gas flush would occur to restore the gas lost while inserting the HDD(s)  2  ( 408 ). The environmental system  16  then maintains desired environmental settings using some or all of the local instruments and devices: a gas concentration sensor  32 , a pressure sensor  34 , heat exchanger  24 , the internal fan  25 , the humidifier  28 , the over pressure valve  36  and the gas inlet  22 . The gas supply  30  would be configured to flush the container  18  with the low density gas such as a helium mixture by a constant, intermittent or instrument regulated flow to maintain the desired atmosphere in the environmental system  16  ( 410 ). While in use, the process may be ended at the discretion of a user ( 412 ). At some point it is likely that a user will want to change out one or more of the HDDs  2  that reside within the environmental system  16 , in the event of this, the process begins again at the acclimation of the replacement HDD  2  ( 414 ). 
     Referring to  FIG. 5  and  FIG. 6 , which are apparatus and method for preemptive acclimation of a HDD  2  to a low density environment. The apparatus involved includes an at least substantially air tight enclosure  46  in which a non-operational HDD  2  may be placed. The enclosure  46  has two valves  38 , a first valve  38   a  used for pumping air out and a second valve  38   b  for pumping a low density gas in. In operation, a HDD  2  which is currently not in operation is placed within the enclosure  46  ( 600 ). The second valve  38   b  of the enclosure  46  is closed ( 602 ). The ambient air is vacuumed from the enclosure  46  through the first valve  38   a  ( 604 ). The first valve  38   a  is then closed and the second valve  38   b  is opened and the enclosure  46  is flushed with a low density gas such as a helium mixture ( 606 ). Both valves  38   a ,  38   b  are then closed and time is given to allow the HDD  2  to fill with the low density gas ( 608 ). The HDD  2  is then removed from the enclosure  46  and placed within the environmental system  16 . If there is considerable time between removal and placing inside the environmental system  16 , the breather hole  12  can covered with suitable adhesive covering during the wait to prevent unnecessary helium mixture leaking ( 610 ). 
     Referring now to  FIG. 7 , which is a block diagram of a modified hard disk drive (modified HDD)  48 . The modified HDD  48  has one or more additional breather holes  12  such that when placed in a new atmosphere, the modified HDD  48  will fill with the ambient gasses more quickly. Due to the resultant increased air flow a more robust chemical and particle filter  14  could optionally be used. These additional holes can be blocked up with a suitable adhesive covering  50  when the environment the modified HDD  48  operates without a need for additional gas exchange. The placement of the additional holes  12  can be positioned to target particular pressure zones within a modified HDD  48 . One breather hole  12  may be positioned such that it is over a low pressure zone and a separate breather hole  12 , would be positioned over a high pressure zone. With this configuration ambient gasses would be drawn through the internal portion of the modified HDD  48  further increasing the rate the drive would fill with ambient gas. 
     Referring now to  FIG. 8  which shows a side view of a sample flying height of a head  6  in a HDD  2 . While running in a low density system the head  6  of a HDD  2  will have a lower flying height h, and in turn a smaller clearance d. Generally all drives address this issue by detecting touchdowns or near touchdowns, measuring or approximating the distances h and d, then cooling or heating the protrusion  52  as necessary to change the distance d. This method is shown in  FIG. 10 . The flying height h would be greatly altered by a moderate to substantial change in environment of the HDD  2 . Great changes in flying height can cause needless touchdowns which cause damage to the disc  4  or head  6 , and thus avoiding moderate to substantial transition phases would be ideal for an operator of the invented environmental system  16 . It is thus important for a user to minimize time in which the environmental system is exposed to external conditions such that transition phases remain small or negligible. Subsequent to this disclosure, HDDs  2  will have an improved ability to detect flying height changes as a result of transitions in environment, thus the care required by a user will decline over time. 
     Other changes that could potentially be made to HDD  2  design would include; the airbearing design could be optimized for operating in a helium mixture environment; the storage density can be increased because the low density environment allows for higher track densities due to less non repeatable run out, only the drives  2  firmware needs to have the provision to make use of this capability; and due to low density environment, drives  2  could spin at higher RPM than in ambient air which would offset some of the power savings but still be a beneficial application for the above mentioned environmental system  16 . 
     Referring to  FIG. 9 , which is a plurality of environmental systems  16 . The invented environmental system can be used in series with others using the same gas supply  30  and data/electrical bus  54 . In series, the invented environmental system  16  each containing HDD arrays  2   a , or servers  3  can save on power consumption over a much larger scale. 
     The foregoing disclosures and statements are illustrative only of the present invention, and are not intended to limit or define the scope of the present invention. The above description is intended to be illustrative, and not restrictive. Although the examples given include many specifics, they are intended as illustrative of only certain possible applications of the present invention. The examples given should only be interpreted as illustrations of some of the applications of the present invention, and the full scope of the Present Invention should be determined by the appended claims and their legal equivalents. Those skilled in the art will appreciate that various adaptations and modifications of the just-described applications can be configured without departing from the scope and spirit of the present invention. Therefore, it is to be understood that the present invention may be practiced other than as specifically described herein. The scope of the present invention as disclosed and claimed should, therefore, be determined with reference to the knowledge of one skilled in the art and in light of the disclosures presented above.