Abstract:
Disclosed is an articulated cable chain  102  that has a flat spring that initiates a first folding curve that holds the articulated cable chain  102  in a tight radius. Once the first folding curve  122  is properly initiated, the remaining folding curves in the articulated cable chain  102  are folded at the proper locations and have a small radii, even though the cable within the articulated cable chain tends to cause the cable chain to maintain a straighter configuration.

Description:
BACKGROUND OF THE INVENTION 
   Customer replaceable units have provided a convenient and simple of way of replacing appliances such as disk drives in servers, RAID devices, etc. Drives, such as hot spares, mirror drives in a RAID unit, or any type of replacement drive can be easily removed or replaced using customer replaceable unit devices. Disk drives can be plugged and unplugged from the chassis of RAID units, servers, computers, etc. with cables having connectors that connect to the back of the unit. Hence, the customer replaceable unit devices have been found to be a practical and convenient way to replace appliances, such as disk drives, that are utilized in the computer and electronics industry. 
   SUMMARY OF THE INVENTION 
   An embodiment of the present invention may therefore comprise a method of folding an articulated cable chain that is connected to a customer replaceable unit in a customer replaceable unit chassis comprising: assembling said cable chain from a plurality of chain links that have a limited arc of rotation, said chain links periodically reversed on said articulated cable chain so that said articulated cable chain forms a plurality of folding curves in sequentially opposite directions along said articulated cable chain when said articulated cable chain is in a retracted position and said customer replaceable unit is in a closed position in said customer replaceable unit chassis, and so that said articulated cable chain can expand to a substantially straight orientation when said customer replaceable unit is in an open position in said customer replaceable unit chassis; providing a flat spring having a predetermined radius with slots formed proximally to ends of said flat spring; placing studs through said slots to secure said flat spring to said cable chain; attaching said studs to predetermined links of said plurality of chain links in said articulated cable chain so that said articulated cable chain substantially conforms to said predetermined radius of said flat spring; moving said customer replaceable unit to an open position to extend said cable chain so that said studs move in said slots which allows said flat spring to flex against said articulated cable chain and generate a force on said articulated cable chain; moving said customer replaceable unit to a closed position so that said force generated by said flat spring on said articulated cable chain initiates a first folding curve in said articulated cable chain and causes said articulated cable chain to fold into a first holding curve that substantially matches said predetermined radius of said flat spring, and also causes additional folding curves to be formed in said articulating cable chain that have a radius that substantially matches said predetermined radius. 
   An embodiment of the present invention may further comprise an articulated cable chain comprising: a customer replaceable unit that is attached to a first end of said articulating cable chain; a customer replaceable unit chassis that is attached to a second end of said articulating cable chain; a plurality of chain links connected to form said articulated cable chain that have a limited arc of rotation, said chain links being periodically reversed on said articulated cable chain to form a plurality of folding curves in sequentially opposite directions along said articulated cable chain; a flat spring having a predetermined radius with slots formed proximally to ends of said flat spring; studs that pass through said slots and attach to predetermined links of said plurality of links that forms said articulated cable chain so that said articulated cable chain substantially conforms to said flat spring such that said flat spring flexes against said articulated cable chain when said articulated cable chain is extended and initiates a first folding curve that substantially matches said predetermined radius of said flat spring and causes additional folding curves to be formed in said articulating cable chain that have a radius that substantially matches said predetermined radius. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a schematic perspective view of an embodiment of a cable chain that is engaged by a flat spring to form a tight radius folding curve. 
       FIG. 1B  is a schematic perspective view of the embodiment of  FIG. 1A  from a different angle than shown in  FIG. 1A . 
       FIG. 2  is a schematic plan view of an articulated cable chain assembly disposed in a chassis of a customer replaceable unit with the customer replaceable unit in a closed position. 
       FIG. 3  is a schematic top view of the articulating cable chain assembly of  FIG. 2  shown with the customer replaceable unit in an open position in a chassis. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1A  is a schematic illustration of a cable chain  100  that includes an articulated cable chain  102  and a cable  104  that is disposed within the interior portion of the articulated cable chain  102 . The articulated cable chain  102  provides protection for the cable by limiting wear of the cable  104  as a result of movement of the cable  104 . The chain  102  also assists in folding the cable in a series of sequential opposite curves in a repeating “S” formation, so that the cable does not become entangled during movement. 
   As shown in  FIG. 1A , flat spring  106  is formed with a predetermined radius to fold the cable chain  100 , so that the cable chain  100  has a radius that substantially matches the radius of the flat spring  106 . For example, a radius of 1 inch may be desirable to fold the cable chain  100 . Stud  110  is connected to link  116  through the slot  108  to hold the flat spring  106  to the cable chain  100 . 
     FIG. 1B  is a perspective view of the articulated cable chain of  FIG. 1A  viewed from a different angle. As shown in  FIG. 1B , stud  120  is connected to link  118  through slot  122  to hold the other end of the flat spring  106  to the cable chain  100 . The slots  108 ,  122  allow the studs  110 ,  120  to move within the slots  108 ,  122  as the articulated cable chain  100  is extended and retracted. Since the radius of curvature of the flat spring  106  is slightly less than the radius of curvature of the cable chain  100 , which is disposed on the outside of the flat spring  106 , slots  108 ,  122  must be provided to allow for movement between the cable chain  100  and the flat spring  106 , as the flat spring  106  is flexed from a resting position, such as shown in  FIGS. 1A and 1B  to a flexed, open position when the cable chain  100  is in an extended position, as disclosed below. 
     FIG. 2  is a schematic plan view of an articulated chain cable  102  that is shown folded in a customer replaceable unit chassis  204 . As shown in  FIG. 2 , the articulated cable chain  102  covers the cable  104 . Cable  104  is connected to the customer replaceable unit chassis  204  at one end and to the customer replaceable unit (CRU)  202  at the other end. As shown in  FIG. 2 , the cable chain  102  is folded to form a series of interlinking folds in the cable chain  102  that curve in opposite directions sequentially along the length of the cable chain  102 . The cable chain links that form the articulated cable chain  102  have a limited arc of rotation so that the cable links rotate in only one direction. The links are assembled to form the articulated cable chain  102 , so that the plurality of folding curves of the articulated cable chain  102  are sequentially reversed to produce the plurality of folding curves in sequentially opposite directions along the length of the articulated cable chain  102 , illustrated in  FIG. 2 . As shown in  FIG. 2 , it is desirable to ensure that the folding curves  122 ,  124 ,  126 ,  128  are tightly formed and are properly initiated when the customer replaceable unit (CRU)  202  is in an extended or open position in the customer replaceable unit chassis  204  and begins to move to a retracted position, such as illustrated in  FIG. 2 . If the folding curves in the articulated cable chain  102  are not properly initiated, the articulated cable chain  102  may not properly initiate a folding action, which may prevent the customer replaceable unit from being retracted into the customer replaceable unit chassis  204  in the manner illustrated in  FIG. 2 . Alternatively, some portions of the articulated cable chain  102  may fold to create the folded curves  122 - 128 , while other portions may not fold properly if the first folding curve in the articulated cable chain  102  is not initiated properly and does not have the proper radius. 
     FIG. 2  illustrates the manner in which the flat spring  106  causes the articulated cable chain  102  to be folded into a tight radius, as shown by folded curve  122 . The first curve  122 , that is closest to the point at which the cable  104  is attached to the customer replaceable unit chassis  204 , initiates the proper folding of the articulated chain  102 . In that regard, the tight radius of the first folded curve  122  causes the additional folded curves  124 ,  126 ,  128  to properly fold into tight radii, as illustrated in  FIG. 2 . In this manner, both the initiation of the first folded curve  122  and the tight radius of the first folded curve  122  that is created by the flat spring  106  causes the remaining portion of the articulated cable chain  102  to fold in the manner shown in  FIG. 2 . 
     FIG. 3  is a schematic illustration of the customer replaceable unit  202  in an extended position in the chassis  204 . As shown in  FIG. 3 , the flat spring  106  is flexed outwardly by the extension of the articulated cable chain  102 , which is caused by the customer replaceable unit  202  being extended to an open position in the chassis  204 . Studs  112 ,  114  hold the flat spring  106  against the articulated cable chain so that the first folding curve  122  is properly initiated in the articulated cable chain  102 . Studs  112 ,  114  hold the flat spring  106  against the articulated cable chain  102  to generate a force against the surface of the articulated cable chain  102  to initiate the first folding curve  122 . In this manner, the entire process of folding the articulated cable chain  102  when the customer replaceable unit  202  is pushed to a closed position is initiated properly and causes the articulated cable chain  102  to fold to create the first folding curve  122  at the proper location along the length of the articulated cable chain  102 . Again, once the first folding curve  122  is properly initiated, the remaining folds will be initiated properly and have a small radius, such as the radius that is created by the flat spring  106 , as shown in  FIG. 2 . 
   The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.