Abstract:
A data storage device chassis for housing a plurality of data storage devices has a plurality of walls at least some of which have at least one guide strip along at least part of the length of the wall to define a plurality of bays in which data storage devices ( 18 ) can be housed. The guide strips support respective data storage devices in the bays such that the data storage devices can be slid into and out of the bays by sliding along the guide strips. The at least some of the walls are composed of a non-metallic material such that the surface of said guide strips along which a data storage device slides is non-metallic. Each of said at least some of the walls have an electrically conductive portion passing through the wall to provide for electrical conduction between the bays thereby providing electrical shielding for data storage devices housed in the bays.

Description:
[0001]    This application claims priority to U.S. provisional application No. 60/383,126, filed May 28, 2002, the entire content of which is hereby incorporated by reference. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of Invention  
           [0003]    The present invention relates generally to a data storage device chassis, a wall therefor, and a data storage device case and clamp mechanism.  
           [0004]    2. Discussion of Related Art  
           [0005]    As is well known, data storage devices, such as disk drive units, are used to store data. In many applications, plural data storage device are housed in a single chassis and are removable therefrom for maintenance or replacement as and when necessary. In practice, it is desirable to fit as many data storage devices in a single chassis as possible in order to save space. A typical known chassis of standard 19″ rack width and height of 3U (5¼″) may hold 12 or 15 data storage devices at most, the devices being arranged in a regular array.  
           [0006]    A number of difficulties arise in the design of a chassis of this type, particularly when trying to accommodate a greater number of data storage devices in a standard volume as space is at a premium and thin chassis walls are therefore required.  
           [0007]    First, it is important to ensure that the cases of the data storage devices are held securely in the chassis and particularly in a way that minimises vibration of the data storage device. In the case of disk drive units, it is important to minimise the rotary vibrations that can arise because of the spinning disk.  
           [0008]    It is furthermore important to minimise any damage to the chassis or data storage device case that might arise on sliding the data storage device in and out of the chassis. Given that data storage devices are typically housed in metal cases, it is important to ensure that metal flakes or other particles do not scrape off the data storage device case or the chassis because such metallic particles can interfere with the proper operation of the data storage device in use. One known solution to this particular problem is to glue or rivet plastics strips along the metal runners of metal walls that define the bays for the data storage devices in the chassis. Practical problems with this approach include the fact that the plastics strips are often not glued or otherwise fixed in the correct place and that they may become loose and even detached after repeated sliding in and out of the data storage devices. The use of discrete plastics strips also increases the parts count and the gluing or other fixing of the plastics strips adds significantly to the labour costs.  
           [0009]    In such a chassis, it is furthermore important to ensure that electromagnetic interference both out of and into the chassis is minimised, not only to meet legal requirements in regard to emissions but also to minimise the possibility of the operation of the data storage devices being affected by stray electromagnetic radiation entering the chassis.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0010]    According to a first aspect of the present invention, there is provided a data storage device chassis for housing a plurality of data storage devices, the chassis having a plurality of walls, at least some of the walls having at least one guide strip along at least part of the length of the wall to define a plurality of bays in which data storage devices can be housed, said guide strips supporting respective data storage devices in the bays such that said data storage devices can be slid into and out of the bays by sliding along the guide strips, said at least some of the walls being composed of a non-metallic material such that the surface of said guide strips along which a data storage device slides is non-metallic, each of said at least some of the walls having an electrically conductive portion passing through the wall to provide for electrical conduction between the bays thereby providing electrical shielding for data storage devices housed in the bays.  
           [0011]    The use of a non-metallic material for the wall and particularly for the guide strip or strips along which the data storage devices slide means that there is no metal-to-metal contact between the data storage device and the wall. This in turn avoids the scraping of metal, which can otherwise lead to formation of metallic particles that can affect performance of the data storage devices. This construction furthermore avoids having to glue or otherwise fix strips of plastics along the guide strips along which the data storage devices slide, thus reducing the parts count and labour costs and avoiding the problem of such plastics strips becoming detached in use. The non-metallic wall can be formed very cheaply and yet have the high stiffness required of such a wall in a data storage device chassis.  
           [0012]    Said guide strips may project into respective bays for supporting respective data storage devices in the bays. As an alternative, the guide strips may be in the form of recesses in the respective walls.  
           [0013]    In an embodiment, the non-metallic material of said at least some of the walls is plastics. Plastics is preferred because it can be manufactured simply at low cost and within a narrow range of dimensional tolerances. Also, through selection of the appropriate plastics material, the walls can have a very high stiffness, which is important in minimising vibration of data storage devices housed in the chassis. In a preferred embodiment, the non-metallic material of said at least some of the walls is polycarbonate.  
           [0014]    In an embodiment, the electrically conductive portion of said at least some of the walls is metal.  
           [0015]    In a preferred embodiment, the non-metallic material of said at least some of the walls is plastics and the electrically conductive portion of said at least some of the walls is metal, each of said walls being formed by over-moulding the metal electrically conductive portion with plastics such that the metal electrically conductive portion is held captive in the plastics part of the wall. The use of over-moulding, which will be discussed further below, allows for simple, low cost and accurate manufacture of the walls. The metal electrically conductive portion preferably has projecting ears that are engaged by the plastics part of the wall to hold the metal electrically conductive portion captive in the plastics part of the wall.  
           [0016]    According to a second aspect of the present invention, there is provided a wall for a data storage device chassis that houses a plurality of data storage devices, the wall having at least one guide strip along at least part of the length of the wall, the guide strip being constructed and arranged to at least partially support a respective data storage device in the data storage device chassis such that said data storage device can be slid into and out of the chassis by sliding along the guide strip, the wall being composed of a non-metallic material such that the surface of said guide strip along which a data storage device slides is non-metallic, the wall having an electrically conductive portion passing through the wall to provide for electrical conduction across the wall to enable electrical shielding for data storage devices housed in the chassis.  
           [0017]    In an embodiment, the non-metallic material of said wall is plastics.  
           [0018]    In an embodiment, the non-metallic material of said wall is polycarbonate.  
           [0019]    In an embodiment, the electrically conductive portion of said wall is metal.  
           [0020]    In a preferred embodiment, the non-metallic material of said wall is plastics and the electrically conductive portion of said wall is metal, said wall being formed by over-moulding the metal electrically conductive portion with plastics such that the metal electrically conductive portion is held captive in the plastics part of the wall.  
           [0021]    The metal electrically conductive portion preferably has projecting ears that are engaged by the plastics part of the wall to hold the metal electrically conductive portion captive in the plastics part of the wall.  
           [0022]    According to a third aspect of the present invention, there is provided a method of manufacturing a wall for a data storage device chassis that houses a plurality of data storage devices, the method comprising: placing a conductive strip in a mould; introducing molten non-metallic material into the mould; and, allowing the molten non-metallic material to solidify; the conductive strip being supported in the mould such that the conductive strip is held captive by the solidified non-metallic material and passes through the non-metallic portion of the wall to provide for electrical conduction across the wall.  
           [0023]    The conductive strip preferably has projecting ears that are engaged by the non-metallic portion of the wall to hold the conductive strip captive in the non-metallic portion of the wall.  
           [0024]    In an embodiment, the non-metallic material of the wall is plastics.  
           [0025]    In an embodiment, the non-metallic material of the wall is polycarbonate.  
           [0026]    In an embodiment, the electrically conductive strip is metal.  
           [0027]    According to another aspect of the present invention, there is provided a data storage device chassis and a data storage device case having a clamp mechanism for clamping the data storage device case in the data storage device chassis, the clamp mechanism comprising: a lever mounted for pivotable movement about a pivot axis between an open position in which the data storage device case is unclamped and a closed position in which the data storage device case is clamped; the lever having a cam surface constructed and arranged to engage a cam surface in the data storage device chassis in the closed position; the lever cam surface having a bevel substantially parallel to the pivot axis and the chassis cam surface having a complementary bevel such that, as the lever is pivoted about the pivot axis from the open position towards the closed position, the bevels on the lever cam surface and the chassis cam surface engage to clamp the data storage device case in the data storage device chassis.  
           [0028]    The use of bevelled cam surfaces causes the data storage device case to be drawn closely into and clamped strongly against the adjacent wall of the data storage device chassis. This gives the effect of an interference fit in the clamped position, whereas sliding in and out of the data storage device can be an easy, almost loose fit. The strong clamp load that can be applied serves to minimise vibrations that may arise during operation of the data storage device.  
           [0029]    In a preferred embodiment, the lever cam surface is positioned at one end of the lever and the opposite end of the lever has a projecting tab that engages in a slot in the data storage device case when the data storage device case is in the clamped position.  
           [0030]    According to another aspect of the present invention, there is provided a data storage device case having a clamp mechanism for clamping the data storage device case in a data storage device chassis, the clamp mechanism comprising: a lever mounted for pivotable movement about a pivot axis between an open position in which the data storage device case is unclamped and a closed position in which the data storage device case is clamped; the lever having a cam surface constructed and arranged to engage a cam surface in a data storage device chassis in the closed position; the lever cam surface having a bevel substantially parallel to the pivot axis and for engagement with a complementary bevel on a said chassis cam surface such that, as the lever is pivoted about the pivot axis from the open position towards the closed position, the bevels on the lever cam surface and the chassis cam surface engage to clamp the data storage device case in the data storage device chassis.  
           [0031]    In a preferred embodiment, the lever cam surface is positioned at one end of the lever and the opposite end of the lever has a projecting tab that engages in a slot in a said data storage device case when the data storage device case is in the clamped position.  
           [0032]    According to yet another aspect of the present invention, there is provided a data storage device chassis for housing one or more data storage devices, the chassis having walls that define an aperture through which a module can be passed to be housed in the chassis, the periphery of the aperture being surrounded by an electromagnetic interference shielding gasket, the gasket having a base portion and an upstanding portion upstanding therefrom that engages a said module when a said module is housed in the chassis, the base portion of the gasket being received in a recess or recesses in the walls of the chassis to retain the gasket in position around the aperture, the recess or recesses having an opening through which the upstanding portion of the gasket projects into the periphery of the aperture.  
           [0033]    This arrangement means that the gasket does not have to be fixed by gluing, rivetting or the like, which reduces labour costs and helps to ensure that the gasket is correctly positioned initially and that the gasket stays in the correct position in use. In practice, the base portion of the gasket will typically be slid into the recess from an end of the recess or recesses during assembly of the chassis.  
           [0034]    The opening of the recess or recesses preferably has a width that is substantially the same as the cross-sectional width of the upstanding portion of the gasket. This arrangement assists in making a close sealing engagement between the gasket and the module as it provides some support for the upstanding portion of the gasket.  
           [0035]    The gasket is preferably generally T-shape in cross-section such that the base portion of the gasket is generally rectangular in cross-section and the upstanding portion of the gasket is upstanding generally centrally therefrom. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]    Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:  
         [0037]    [0037]FIG. 1 is a perspective view from the front of an example of a data storage device chassis according to an embodiment of the present invention;  
         [0038]    [0038]FIG. 2 is a perspective view from the rear of the chassis of FIG. 1;  
         [0039]    [0039]FIG. 3 is a side elevation of an example of a mid-wall of a data storage device chassis in accordance with an embodiment of the present invention;  
         [0040]    [0040]FIG. 4 is an end elevation of the wall of FIG. 3;  
         [0041]    [0041]FIG. 5 is a plan view from above of the wall of FIG. 3;  
         [0042]    [0042]FIG. 6 is a side elevation of an electrically conductive strip of the wall of FIG. 3;  
         [0043]    [0043]FIGS. 7A to  7 C are partially sectioned views from above of an example of a data storage device having a clamp mechanism engaging a wall of a data storage device chassis in accordance with an embodiment of the present invention, the clamp mechanism being shown in a fully open, partially open and a clamped position respectively; and,  
         [0044]    [0044]FIG. 8 is a sectioned perspective view of the periphery of openings at the rear of a data storage device chassis in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0045]    Referring initially to FIGS. 1 and 2, a generally box-like data storage device chassis  10  has side walls  11 , a top wall  12  and a bottom wall  13 . Three vertical mid walls  14  pass from the front  15  to approximately the mid point of the chassis  10 . Each mid-wall  14  has on each side five guide strips  16  and the inner most facing surfaces of the side walls  11  have similar guide strips  16  which together in this example define a regular array of 4×4 bays  17 . Each bay  17  can receive a data storage device  18  which can be slid into and out of the base  17  through the open front  15  of the chassis  11 , the guide strips  16  providing the surface along which the cases  19  of the data storage devices  18  slide.  
         [0046]    A preferred arrangement for the walls  14  will now be described with particular reference to FIGS.  3  to  6 . Each wall  14  is generally rectangular in shape. The main body of the wall  14  is made of a non-metallic material, preferably plastics and in one embodiment polycarbonate. The wall  14  contains a conductive strip  20 , which may be an aluminium casting. In the most preferred embodiment, the wall  14  is formed by over-moulding the conductive strip  20  with the plastics material of the body of the wall  14 . For this purpose, the conductive strip  20  has through holes  47  which can be used to mount the conductive strip  20  on pegs in a moulding tool whilst plastics material is introduced into the tool. The conductive strip  20  has plural projecting ears  48  on each side which are encapsulated by the moulded plastics material of the wall  14  in order to hold the conductive strip  20  securely in the formed wall  14 . Moreover, as can be seen particularly clearly in FIG. 3, the guide strips  16  overlie the conductive strip  20 , again serving to hold the conductive strip  20  securely in place.  
         [0047]    This arrangement for forming the wall  14 , including the selection of materials and the method of manufacture, has several distinct advantages in the context of a wall as used in a data storage device chassis  10 . In particular, in a chassis  10  for a plurality of data storage devices  18 , space is at a premium as it is always desirable to fit as many data storage devices as possible across the standard rack width of 19″. The dividing walls must therefore be thin. On the other hand, it is also desirable to construct the chassis  10  so that the chassis  10  can itself act to minimise vibration passing into and out of the data storage devices  18 . Where the data storage devices  18  are disk drives which have spinning disks, it is important to damp the rotary vibrations that can arise during operation of the disk drives. These vibration damping requirements imply that the walls  14  should have a high stiffness. Last, it is necessary that the walls  14  be formed within close tolerances given their function not only in supporting the data storage devices but also in minimising vibrations. All of these requirements are met in the preferred embodiment of the wall  14  and its method of manufacture as described above.  
         [0048]    In the preferred embodiment, the walls  14  each have a generally trapezoidal slot  21  in the region of the wall  14  at the front of each bay  17 . Each of these trapezoidal slots  21  has a bevelled leading edge  22 . Moreover, a short keying rib  23  is provided on each side of the wall  14  at the portion at the rear of each bay  17 . The chassis  10  has similar trapezoidal slots  24  and short keying ribs  25  for the left most and right most bays. The function of these features will be discussed further below.  
         [0049]    Referring now to FIGS. 7A to  7 C, each data storage device  18  is generally rectangular in plan and fits snugly in a respective bay  17  in the chassis  10 . The case  19  contains the actual storage device such as a hard disk, read/write heads, etc. (not shown). The data storage device  14  has a clamp mechanism  30  which includes an operating lever  31  which is pivotable about a pivot  32  which is perpendicular to the direction of insertion of the data storage device  18  and parallel to the bevelled edge  22  of the trapezoidal slots  21 , 24 . The operating lever  31  has a cam surface having a corresponding bevel  33  on a leading edge. The lever  31  furthermore has a projecting stop  34  close to the bevel  33 .  
         [0050]    As a data storage device  18  is slid into a bay  17  of the chassis  10 , the case  19 , which is typically metal, slides along the guide strips  16  that define the bay  17 . Because the guide strips  16  are provided by the non-metallic and preferably plastics wall  14 , there is no sliding of metal on metal. This serves practically to reduce to zero the possibility of metal flakes or particles scraping off any of the components when the data storage device  18  is moved into and out of position in the chassis  10 , thereby reducing the risk of damage or other interference to the electronic components of the chassis  10  and the data storage devices  18 . Moreover, avoiding the metal-on-metal contact of typical known arrangements means that the action of sliding the data storage devices  18  in and out has a much better “feel” for the user or operator.  
         [0051]    The case  19  of the data storage device has short elongate keying recesses  26  which correspond to and receive the respective keying ribs  23 , 25  of the walls  14  or chassis  10  as the data storage device  18  moves towards its fully home position in the bay  17 . The ribs  23 , 25  are a loose fit in the recesses  26  so that they do not interfere with engagement of the data and power connector at the back of the data storage device  18  with the data and power connector provided in the chassis  10  at the rear of each bay  17 . These keying ribs  23 , 25  and recesses  26  help to ensure that the data storage device  18  is inserted the right way up and, indeed, help to ensure that the correct module is being inserted into the chassis  10 .  
         [0052]    As can be seen in FIG. 7A, as the data storage device  18  moves towards its fully home position, the stop  34  of the lever  31  abuts the leading edge of the wall  14  (or chassis wall  11  as the case may be). At that point, the lever  31  is then pivoted, this action causing the bevel  33  of the lever cam surface to engage the bevel  22  in the trapezoidal slot  21 , 24  in the wall  14  or chassis  10  as the case may be. This can be seen most clearly in FIG. 7B. Further pivoting of the lever  31  and the resultant action of the bevelled surfaces  33 , 22  against each other clamps the case  19  of the data storage device  18  securely against the wall  14 , 11  on that side. The end of the lever  31  opposite the cam surface  33  has a projecting tab  35  on the end of a resilient U-shape formation  36  which engages in a slot  37  in the case  19  when the data storage device  18  is in the fully clamped position shown in FIG. 7C. This provides a lock against accidental opening of the clamp mechanism  30 .  
         [0053]    In the fully clamped position, the metal walls of the data storage device case  19  engage the conductive strips  20  of the mid walls  14  and also the metal side walls  11  of the chassis  11 , optionally through metal leaf springs mounted on the case  19 . This metal-to-metal contact provides an earth path between all of the data storage devices  18  in the bays  17  of the chassis  10 . This serves to reduce electromagnetic interference either entering or leaving the chassis  10 . Thus, despite the non-metallic material used for the walls  14 , earthing conduct can be made through the walls  14  in a simple manner and is effected whenever the data storage device  18  is in its clamped position in a bay  17 .  
         [0054]    In a manner known per se, the pivot  32  may travel slightly in a direction along the length of the case  19  when the data storage device  18  is moved into its fully home position. Similarly, in a manner known per se, a torsion spring may be mounted around the pivot  32  which winds up to its full force as the lever  31  is moved to its home position. These effects act together to provide a load on the case  19  towards the rear of the chassis  10 , which serves to ensure that the power and data connections between the data storage device  18  and the chassis components at the rear of the data storage device  18  are strongly made.  
         [0055]    The combined action of the bevelled cam surface  33  of the lever  31  engaging the bevelled cam surfaces  22  of the trapezoidal slot  21 , 24 , the engagement of the cam surface  33  in the trapezoidal slot  21 , 24  itself, and the engagement of the data and power connector on the data storage device  18  with the connector on the motherboard at the rear of the bay  17 , provides for a secure 3-point mounting of the case  19  in the bay  17 , with the case  19  being locked in three perpendicular axes. This results in extremely efficient damping of vibrations and provides strong resistance against shock.  
         [0056]    Referring now to FIG. 8, there is shown a portion around the periphery of apertures  40  at the rear of the chassis  10 . These apertures  40  can receive a module, such as a power supply and cooling fans, etc., for data storage devices  18  located in the chassis  10 .  
         [0057]    It is desirable in practice to provide for electromagnetic shielding around the periphery of these openings, both to prevent leakage out and leakage in of electromagnetic interference. Conventionally, such shielding has been provided by strips of short metallic fingers which are glued around the periphery of the aperture  40 . The gluing of such fingers increases labour costs and it is also a fact that such fingers or similar may well not be glued in the correct place in the first instance and that they can become detached during use.  
         [0058]    Accordingly, in the preferred embodiment, a gasket  41  of generally T-shape cross section is employed. The gasket  41  has a plastics base  42  with an upstanding urethane foam portion  43 , which are both entirely covered by a woven fabric covering  44  which is either made of metallic material or which is metallised. A preferred material for the metal or metallised coating is nickel or silver. A suitable gasket  41  is manufactured by Schlegel Systems Inc. The region of the chassis  10  around the periphery of the apertures  40  has a recess  45  of rectangular cross section which can receive the base portion of the gasket  41 , the recess  45  having an opening  46  through the chassis wall through which the upstanding portion of the gasket  41  projects into the aperture  40  in the chassis  10 . The depth of the recess  45  is selected so that the gasket  41  is compressed somewhat when a module is loaded in the aperture  40 . The gasket  41  can be introduced into the recess  45  during assembly of the chassis  11  by sliding the gasket  41  in from one open end of the recess  45 .  
         [0059]    Not only does the preferred gasket  41  provide for good electromagnetic shielding, it also provides a good air seal around the module in the aperture  40 . This is of particular advantage in a data storage device chassis  10  given that temperature control of the data storage devices  18  is provided by special cooling fans under specific software control and it is therefore desirable to prevent air leaking into or out of the chassis  10  other than through the air flow paths occupied by the cooling fans.  
         [0060]    Embodiments of the present invention have been described with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.