Abstract:
A carriage, provided with a mounting for one or more media devices is slideably mountable in a system unit (for example a computer system unit) such that the carriage may be slid out of an aperture the system unit. The slideable carriage means that the system unit does not need to be opened in order to insert, remove, or replace a media drive. For example, a media drive can be removed from the system unit by sliding the carriage out of the system unit, disconnecting cables from the media drive and the removing the media drive from the carriage. Similarly, a media drive can be installed in the system unit by mounting the media drive in the carriage, connecting cables to the media drive and reinserting the carriage within the system unit. The use of the slideable carriage is particularly useful for rack mountable systems where it is undesirable to have to remove the system unit from the racking system to insert a media drive.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to improving the ease of maintenance and enhancement of computer systems in the field. 
     It is standard practice in designing computer systems to provide for components that can be swapped in and out. For example, a system unit typically has one or more slots on its front for receiving devices such as disk and tape drives, which can be swapped in and out. However, in practice, such operations can be awkward, particularly for systems intended to be rack-mounted, due to the need to remove the system unit from the rack, and then to open the system unit cover (which is typically formed in the upper surface thereof) in order to gain access to the mounting bracket and the connecting cables for the media drive(s). After securing the drive to the mounting brackets within the unit, and connecting the cables, the system unit cover can be replaced and the unit put back into the rack. 
     Accordingly the present invention seeks to provide for more ready replacement and/or installation and/or removal of media devices in a computer system unit. 
     SUMMARY OF THE INVENTION 
     Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as appropriate and not merely as explicitly set out in the claims. 
     In accordance with one aspect of the invention, there is provided a carriage for media devices slideably mountable in a system unit such that the carriage may be slid out of an aperture in the system unit, wherein the carriage is provided with a location for receiving at least one media drive. 
     The provision of the slideable carriage means that the system unit does not need to be opened in order to insert, remove, or replace a media drive. 
     For example, with an embodiment of the invention, steps in removing a media drive from the system unit can include sliding the carriage out of the system unit, disconnecting cables from the media drive and removing the media drive from the carriage. The disconnection of the cable from the media drive and the removal of the media drive from the carriage can thereby be done outside the system unit and without needing to open its cover. 
     Similarly, with an embodiment of the invention, steps in installing a media drive in the system unit can include sliding the carriage out of the system unit, mounting the media drive within the carriage, connecting cables to the media drive and reinserting the carriage within the system unit. The securing of the media drive to the carriage and the connection of the cable to the media drive can thereby be done outside the system unit and without needing to open its cover. 
     The securing of the carriage within the system unit can be achieved using suitable fastenings. For example, the carriage can be screwed to the system unit and/or it can be retained therein by means of a face plate that is secured to the system unit. 
     Similarly, the media drives can be secured within the slideable carriage using suitable fastenings, for example screws that pass through a side of the carriage into predetermined threaded holes in sides of the media drives. 
     In a preferred embodiment of the invention, the carriage is a single assembly with all the necessary fastening screws for attaching media drives and for securing the carriage in the system unit held in place. The carriage can be supplied with electromagnetic conductor blanks, held with spring clips, in the front of the carriage, so that full electromagnetic shielding is provided with no drives in place. When it is desired to install a drive, an appropriate one of the electromagnetic blanks is popped out and the drive can be inserted in its place. 
     In an embodiment of the invention, the aperture is in the front surface of a casing of the system unit, with a media bay being located behind the aperture. Alternatively, the aperture could be in the rear of the system unit, or indeed in any face of the system unit that is readily accessible. In the case of a rack mountable unit, the apertures are preferably located in the front and/or rear surfaces of the system unit, as these can enable access to the media drives without removing the system unit from the rack. 
     In accordance with another aspect of the invention, there is provided a system unit comprising an aperture in a surface thereof and a carriage as set out above, slideably mountable in the system unit such that the carriage may be slid out of the aperture. 
     In accordance with a further aspect of the invention, there is provided a method of installing a media drive in a system unit, the method includes: mounting a media drive in the carriage, configured to be slideably mounted within the system unit and connecting at least one cable to the media drive; and then sliding the carriage through an aperture in a surface of the system unit. 
     A method of removing a media drive from a system unit following installation thereof as set out above, the method includes: sliding the carriage out of the system unit; disconnecting cables from the media drive; and then removing the media drive from the carriage. 
     Thus, an example of the invention can avoid the need to remove the main cover of the system unit and, in the case of a rack mountable system unit, the removal of the system unit from the rack. It finds particular application in rack-mountable computer system units for telecommunications applications, where it is important to minimize down times when system changes and maintenance operations are performed. As the unit does not need to be removed from the rack and opened, removing, replacing and installing drives can be done very quickly and efficiently. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the present invention will be described hereinafter, by way of example only, with reference to the accompanying drawings in which like reference signs relate to like elements and in which: 
     FIG. 1 is a perspective view from the front of an embodiment of the invention including sacrificial transport brackets; 
     FIGS. 2A and 2B are plan and front views, respectively of the embodiment of FIG. 1 with alternative mounting brackets, and FIG. 2C is a side view showing the mounting holes for alternative types of mounting arrangements; 
     FIG. 3 is perspective view from the rear of the embodiment FIGS. 1 and 2 illustrating a removable top cover; 
     FIG. 4 is an exploded view of the aforementioned embodiment; 
     FIG. 5 is a front view of the aforementioned embodiment; 
     FIG. 6 is a rear view of the aforementioned embodiment; 
     FIG. 7 is perspective view from the front of the embodiment FIGS. 1 and 2 illustrating the removal of a slideable carriage for one or media drives; 
     FIGS. 8A,  8 B, and  8 C are plan, front, side and perspective views of the carriage; and 
     FIG. 9 is a flow diagram setting out the steps in replacing a media drive. 
     FIG. 10 is a flow diagram illustrating the steps of removing a media drive. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, a particular embodiment of the invention will be described by way of example only. 
     FIG. 1 is a perspective view of a system unit  10  for use in a rack-mountable system. In a particular example described herein, the system unit is a computer system unit for forming a computer server for a telecommunications application, for example an Internet server. As shown in FIG. 1, the unit  10  has a front surface  12  formed by a front wall, a rear surface  14  formed by a rear wall, a left end surface  16  formed by a left side wall, a right end surface  18  formed by a right side wall, a lower surface  20  formed by a base wall and an upper surface  22 , in the present example formed by a cover  30 . As shown in FIG. 1, the system unit  10  is provided with sacrificial transport flanges  24 , which extend above and below the system unit. This optional feature is removed before installation of the system unit  10  in a rack. 
     The system unit  10  is constructed with an extremely robust chassis  11 , with the various walls  12 - 20  and the cover  30  forming the casing of the chassis  11  as well as internal walls (not shown) being formed of heavy gauge steel. The walls of the chassis can be made, for example, from electroless nickel-plated mild steel with a thickness of, for example, 1.5 to 2.0-mm. 
     The steel chassis  11  is pre-formed with mounting holes for the attachment of mounting flanges or a slide mechanism to enable the system unit  10  to be provided with a wide variety of mounting options and rack sizes. Mounting flanges can be provided to suit standard 19-inch, 23-inch, 24-inch or 600-mm nominal frame widths. (One inch=approximately 25.4 mm). 
     FIG. 2A is a plan view of the unit  10  showing the upper surface  22 /cover  30  and various options for flanges  26  with the displacements from the front surface indicated in mm. 
     FIG. 2B is a front view of the unit  10  showing the front surface  12  and two different examples of mounting flanges  26 . The mounting flange shown to the left (as seen in FIG. 2B) is provided with a handle to facilitate insertion and removal of the unit  10  from the racking system, whereas the flange  26  to the right (as viewed in FIG. 2B) is not provided with a handle. 
     In the present example, the mounting flanges can be attached using screws which pass through the mounting flange into threaded holes in the end walls  14 ,  16  at either side of the chassis  11  of the unit  10 . FIG. 2C is a side view of the system unit  10 , showing the holes in the side of the system unit  10  for the mounting of flanges or a slide mechanism. Vertical rows of holes are for the attachment of flanges to be attached to vertical rack components, and horizontal rows of holes provide for the attachment of a runners for permitting a slideable mounting of the system unit in a rack. 
     FIG. 3 is a perspective rear view of the unit  10  showing the cover  30  that forms the top surface  22  of the unit  10 . As can be seen, the cover  30  is provided with front locating flanges  32  that, in use, engage a co-operating front flange  31  of the body of the chassis  11 . Side flanges  33  engage either side of the end walls forming the left and right ends  16  and  18  of the chassis  11 . Detents  34  on those end walls engage within L-shaped slots  35  in the side flanges  33  so that the cover may be lowered onto the top of the chassis  11  and then moved forwards so as to cause the detents  34  to latch within the slots  35 . At the rear of the cover  30 , a rear flange  36  with a lower lip  37  engages over an abutment  38  at the top of the rear end wall  14  of the casing  10 . The cover can be secured to the remainder of the chassis  11  by means of a screw  39  that passes through this rear flange into a threaded hole in the abutment  38 . 
     FIG. 4 is an exploded perspective view from the front of the system unit  10 . This shows a motherboard  40  that is mounted on a horizontal mounting plane  41  within the chassis  11 . Mounted on the motherboard  40  are between one and four processor modules  42 . A riser card  44  can receive a plurality of dual in-line memory modules (DIMMs)  46 . Further DIMMs  46  can be received directly in slots in the motherboard. A slideable carriage  48  is provided for receiving one or more media drives. 
     As shown in FIG. 4, the slideable carriage  48  can receive up to two media drives. In the present instance, two media drives including a digital audio tape (DAT) drive  50  and a CD-ROM drive  52  are provided. Appropriately configured metal cover plates  54  and  56  are provided for the media drives  50  and  52 . A disc bay assembly  58  provides a small computer system interface (SCSI) backplane and cables for receiving one or more SCSI media drives, such as a SCSI disc drive  60 . Although, in the present instance, the drives are controlled via a SCSI-type interface, it will be appreciated that another media drive interface (e.g., IDE) could be used. A SCSI card (not shown) is located within the chassis to the front of the motherboard. A bezel (decor panel)  62  is provided for covering ventilation holes  63  in the front wall  12  of the chassis  11 . A bezel  64  is provided for covering the media drives  50 ,  52  and  60 . 
     A fan control module  66  controls the operation of processor fans  68  and system fans  70 . A power sub-assembly that includes a power sub-frame  72  with a power distribution board assembly, is provided for receiving three separate power supply units  74 . An alarms module in the form of an alarms card  78  enables the signalling of alarms to the outside world, and is also connected to an LED card  2  for signalling alarms locally on the front of the unit  10 . A power switch  82  is also provided on the front surface of the unit  10 . FIG. 4 also illustrates one PCI card  84  to be received within a PCI slot  85  on the motherboard  40 . 
     FIG. 5 is a front view of the unit  10  showing the bezels  62  and  64 , a power and alarm panel  90  which includes the power switch  82  and a number of status light emitting diodes (LEDs)  92 . FIG. 5 also illustrates the slots  86  and  88  for the media drives such as media drives  50  and  52  shown in FIG.  4 . 
     FIG. 6 is a rear view of the unit  10  in a configuration with three DC power supply units  74 A,  74 B and  74 C. Each of the power supply units  74 A,  74 B and  74 C is the same, and provides redundant power for the unit  10 . However, as will be seen later, one or more of the DC power supply units could be replaced by AC (mains) power supply units. The power supplies are hot swappable (i.e., while the system is running), as long as they are swapped one at a time. 
     With regard to power supply unit  74 A, it can be seen that this is provided with a handle  94  that is used for inserting and removing the power supply unit  74 A. The handle  94  includes a flange portion that is able to receive a screw  95  for securing the power supply unit to the chassis  11 . First and second power cable sockets  96  and  98  are shown. 
     Also shown is a grounding plate  100  that is secured by knurled nuts  102 ,  104  and  106  to grounding studs  103 ,  105  and  107 . Grounding stud  103  provides a connection directly to the chassis  11  of the unit  10 . Grounding studs  105  and  107 , on the other hand are electrically isolated from the chassis by an insulating board and are instead connected to logic ground (i.e. the ground of the electronic circuitry). By means of the grounding plate  100 , logic ground can be connected directly to chassis ground. The provision of this grounding plate provides for optional tying of logic ground to chassis ground. It will be noted that each of the power supply units  74  is provided with a similar grounding plate  100 , for connection to corresponding grounding studs. If it is desired to isolate logic ground from chassis ground, it is necessary to remove the grounding plate  100  from each of the power supply units  74 A,  74 B and  74 C. 
     An isolated ground system is needed in some telco applications when operating in a Regional Bell Operating Company (RBOC) mode. When operating in such a mode, the chassis and logic ground are connected at a remote location to provide, for example, lightning protection. In this case two-hole lugs  101  having a pair of holes  111  to fit over the pair of grounding studs  105  and  107  are provided for each of the power supply units  74  and are secured over the studs using nuts  104  and  106 . A similar two-hole lug  101  is secured to the grounding studs  108  and is secured with similar nuts. Earthing wires  109  from each of the two-hole lugs  101  on the power units and the chassis then are taken to the remote, earthing location. The studs  103   105 ,  107  and  108  are of a standard thread size (M 5 ). The studs  105 / 107  and the studs  108  are at a standard separation (15.85 mm). The studs  105 / 107  are self-retaining in the insulated board on the power supply units. The stud  103  is self-retaining in the casing of its power supply unit  74 . The suds  108  are also self-retaining in the system unit chassis. 
     In a non-isolated ground situation, chassis ground can simply be tied to a desired ground potential (for example, to the racking system) by connecting a grounding cable to grounding studs  108  provided on the rear of the chassis. A further earth connection is provided via the power cables for the power supplies. 
     FIG. 6 also illustrates rear ventilation holes  110  through which air is vented from the system. FIG. 6 also shows the alarms module  78  with a serial connector  112  enabling connection of the alarms module to a network for the communication of faults and/or for diagnostic operations on the unit  10  to be performed from a remote location. FIG. 6 also shows a number of PCI cards  84  received within respective PCI slots  116 . A number of further external connections  114  are provided for connection of serial connections, parallel connections and SCSI connections, and for the connection of a keyboard or a Twisted-Pair Ethernet (TPE) connector. 
     FIG. 7 is a perspective view of the front of the system unit  10  showing, in more detail, the mounting of the media devices  50  and  52  in the slideable carriage  48 . FIG. 7 also shows the metal cover plates  54  and  56  for the media drives  50  and  52 , that in use complete the electromagnetic shielding for the system unit  10 . A front bezel  64  with apertures  86  and  88  for the media drives  50  and  52 , respectively can be secured to the front of the system unit by means of  1 / 4  turn fasteners. 
     The chassis  48  defines an upper compartment (or a first drive location) for the first media drive  50  and a lower compartment (or second drive location) for a second media drive  52 . Each of the compartments for the media drives is provided with four screws  130  for screwing into threaded holes in the sides of the media drives, which holes are provided at standard positions. The screws  130  are preferably self-retaining in the slideable carriage  48  so that they cannot fall out. Zero, one or two media drives can be mounted in the present example of the carriage  48 . Once the media drives have been secured into position in the carriage  48 , standard connectors (not shown) at the rear of the media drives  50  and/or  52  can be connected to corresponding connectors. These include signal connectors  126  and  128 , for the media drives  50  and  52  respectively, on a flexible cable  124  which can be a SCSI standard cable, or an IDE standard cable, as appropriate. Power connectors  127  on power cables  129  also need to be connected. The cables are configured to be of sufficient length to be able to extend out of the aperture in the system unit whereby connection of the connectors may readily be effected outside the system unit. 
     The carriage  48  is provided with flanges  122  at the upper and lower edges thereof. These flanges are arranged to form guide followers that engage with corresponding guides  120  provided at upper and lower portions at either side of a bay  138  for receiving the carriage. When the carriage  48  has been slid fully back into the bay  138 , the carriage  48  can be secured in place by means of screws  132  provided on small flanges  133  at the front of the carriage  48 . These screws  132  engage in threaded holes  134  provided in small corresponding flanges  135  at the left and right sides of the bay  138 . These screws  132  are also arranged to be self-retaining in the flanges  133  so that they cannot be lost. The cover plate(s)  54  and/or  56  can then be screwed in place in front of the media drives  50  and  52  by means of further screws, which in the preferred embodiment are self-retaining in the cover plate(s)  54 / 56  concerned. The front bezel  64  can be secured in place (in the present example by ¼ turn fasteners). 
     As an alternative to providing screws for securing the media drives in the carriage, another arrangement could be provided, for example using a resilient or other latching mechanism. As a further alternative, a simple friction fit could be employed, for example by fitting the drive between flanges. Similarly, as an alternative to providing screws for securing the carriage in the system unit, another arrangement could be provided, for example using a resilient or other latching mechanism. As a further alternative, the cover plates  54  and  46  could be used to this effect. 
     However, in the particularly preferred embodiment, screws are used for securing the media drives within the carriage  48 , for securing the carriage to the system unit chassis  11  and for securing the cover plates  54 / 56  to the system unit chassis  11 . Each of these screws is arranged to be self-retaining so that the carriage  48  is provided as an integral, user friendly unit. When the system unit is initially supplied, metallic electromagnetic conduction blanks with spring clip fastenings are mounted at the front of each vacant compartment in the carriage. In the absence of a media drive in the compartment of the carriage, this effectively blanks the front panel of the location for mounting the drive. The metal electromagnetic conduction blanks can be provided with a plastics cover for decorative and electrical insulating purposes. These blanks will be behind the cover plates  54  and  56  and behind the bezel  64 . When it is desired to install a media drive, an appropriate blank can be popped out and replaced with the drive. 
     FIGS. 8A,  8 B and  8 C are front, plan and side views of the carriage  48 . The carriage  48  is substantially “U” shaped and the body of the carriage can be stamped from a single piece of sheet metal to define a base  150  and two side walls  152  and  154 . Part way (approximately half way) up both of the walls an inwardly facing lip  156  is formed that acts to separate the carriage into an upper compartment  158  and a lower compartment  160 , each for receiving a media drive  50 , 52 . Zero, one or two media drives can be mounted in the present example of the carriage  48 . However, it will be appreciated that the carriage could similarly be subdivided into more compartments, or could alternatively be configured to provide a single compartment. Also, the sizes of the compartments could be set to be the same or different by setting the lip(s) at appropriate positions. Each of the compartments  158 ,  160  for the media drives is provided with four screws  130  for screwing into threaded holes in the sides of the media drives, which are provided at standard positions. The screws  130  are preferably retained in the slideable carriage  48  so that they cannot fall out. The flanges  122  at the upper and lower edges of the carriage  48  are stamped and folded from the sheet of metal and to form guide followers for engaging with the guides (e.g. the “U”-shaped guide channels  120  illustrated in FIG. 7) provided at upper and lower portions at either side of the bay  138  for receiving the carriage. The flanges  133  at the front of the carriage  48  can also be formed by suitable stamping and folding of the sheet metal used to form the carriage  48 . The screws  132  for mounting the carriage in the system unit chassis  11  are preferably also self-retaining so that they cannot be lost. 
     To avoid a potential loss of components and for the convenience of users, the cover plates  54  and  56  are preferably supplied screwed to the system unit chassis  11 . The carriage can be supplied empty in place behind the cover plates  54  and  56  in the media drive bay. The carriage can be supplied with electromagnetic conduction blanks for blanking plates  180  (see FIG. 8B) at the front of each drive compartment. The blanking plates can be held in the front of the carriage by a resilient member  182 . The cover plates  54  and  56  will then hold the blanking plates in place. If and when a media drive is inserted, the appropriate blanking plate can then be removed. 
     FIG. 9 is a flow diagram illustrating the steps of installing a media drive for the first time. 
     In step S 10 , the plastic media cover (bezel  64 ) is removed by undoing six ¼ turn fasteners. 
     In step S 12 , an earthing strap is connected to an earthing stud on the front of the chassis (not shown in FIG.  7 ). 
     In step S 14 , the metal covers  54  and  56  are removed. 
     In step S 16 , the screws  132  are undone to release the carriage. 
     In step S 18 , the carriage is slid out. 
     In step S 20 , the relevant electromagnetic conduction blank is removed. 
     In step S 22 , the power and signal cables are attached to the media drive and the media drive is secured in the appropriate place in the carriage using the four retained screws  130  provided. (These operations can be performed in any desired order). 
     In step S 24 , the carriage is slid back into the system unit chassis  11 . 
     In step S 26 , the screws  132  are done up to secure the carriage in the chassis. 
     In step S 28 , the cover plates  54  and  56  are reattached using the self-retaining screws provided. 
     In step S 30 , the earth strap is disconnected. 
     In step S 32 , the plastic decor panel is re-attached using the ¼ turn fasteners. 
     FIG. 10 is a flow diagram illustrating the steps of removing a media drive. 
     In step S 50 , the plastic media cover (bezel  64 ) is removed by undoing six ¼ turn fasteners. 
     step S 52 , an earthing strap is connected to an earthing stud on the front of the chassis (not shown in FIG.  7 ). 
     In step S 54 , the metal covers  54  and  56  are removed. 
     In step S 56 , the screws  132  are undone to release the carriage. 
     In step S 58 , the carriage is slid out. 
     In step S 60 , the power and signal cables are removed from the media drive and the media drive is released from the carriage by releasing the four retained screws  130 . (These operations can be performed in any desired order). 
     In step S 62 , the relevant electromagnetic conduction blank is clipped back in (or alternatively a new media drive can be inserted as at step S 22  of FIG.  9 ). 
     In step S 64 , the carriage is slid back into the system unit chassis  11 . 
     In step S 66 , the screws  132  are done up to secure the carriage in the chassis. 
     In step S 68 , the cover plates  54  and  56  are reattached using the self-retaining screws provided. 
     In step S 70 , the earth strap is disconnected. 
     In step S 72 , the plastic decor panel is re-attached using the ¼ turn fastenings. It will be appreciated that the provision of the slideable carriage greatly facilitates the addition, replacement or removal of a media drive in that access to the media drives for replacement can readily be obtained at the front of the system unit  10  without needing to remove the system unit  10  from the racking in which it is held. 
     It will be appreciated from the above, that an embodiment of the invention facilitates the installation, removal or replacement of a media drive by avoiding the need to open the main cover of the system unit and, in the case of a rack-mounted system, by avoiding the need to remove the system unit from the rack. Moreover, the provision of self-retaining screws, means that the carriage is provided as an integral unit, without needing loose fastenings which might get lost or, even worse, fall within the system unit and cause a potential hazard. 
     It will be appreciated that although particular embodiments of the invention have been described, many modifications/additions and/or substitutions may be made within the spirit and scope of the present invention. Accordingly, the particular example described is intended to be illustrative only, and not limitative.