Patent Document

TECHNICAL FIELD 
       [0001]    This invention relates generally to a transmission apparatus for tape cartridge handling, and relates more particularly, though not exclusively, to a transmission apparatus for tape cartridge handling in a tape library. 
       BACKGROUND 
       [0002]    Loading robots are typically used to load tape cartridges into their respective slots in tape libraries. In order to store as many tape cartridges as possible in a tape library, it is desirable to minimize the space occupied by each slot so as to maximize the number of slots that may be provided in a tape library of a given form factor. 
         [0003]    For a small slot size, it is necessary for the loading robot to have precise positioning capabilities so as to be able to correctly insert the tape cartridge with little clearance between the slot and the tape cartridge. It is also desirable for the loading robot to have a low profile so as to take up less space in the tape library and allow more room for storage. 
         [0004]    Currently, loading robots are typically driven by linear slides or belt drives. These are adapted to move a tray supporting a tape cartridge up and down with respect to vertical posts. The loading robot also moves horizontally along a defined path of the tray. The tray has to stop at specific heights with great accuracy to enable the loading robot to deposit a tape cartridge into a slot since the slots in a tape library are normally vertically stacked into columns of slots. 
         [0005]    There are limitations to using linear slides or belt drives for moving the tray in a loading robot. Although accurate, linear slides are costly to implement. Belt drives are known to stretch after a period of use, thereby losing precision. 
         [0006]    To increase storage in a tape library without substantial increases in costs, there thus needs to be a low-cost, precise and robust transmission system to enable the loading robot to work with storage slots that occupy less space. 
       SUMMARY 
       [0007]    A transmission apparatus is provided for use in a tape library. The apparatus has a tray for transporting a tape cartridge and a plurality of pinion gears operably connected to each other and being rotatably attached to the tray. There is also a plurality of vertically disposed racks for engagement by the plurality of pinion gears for rotational movement therealong. 
         [0008]    The plurality of pinion gears may be mounted to a plurality of shafts. The plurality of shafts may comprise a drive shaft and a plurality of driven shafts. The plurality of shafts may be operably connected to one another via a bevel gear train between the drive shaft and each of the driven shafts. 
         [0009]    The plurality of pinion gears may comprise four pinion gears, each pinion gear being disposed at, immediately adjacent, adjacent or near each one of four corners of the tray. 
         [0010]    Each of the plurality of vertically disposed racks may be mounted on a frame. At least two of the plurality of vertically disposed racks may be adjustable relative to their frames for adjusting an incline in the tray. At least one rack of the plurality of vertically disposed racks may be fixed to its frame. 
         [0011]    The transmission apparatus may further comprise a sensor for measuring the incline of the tray. 
         [0012]    The transmission apparatus may also comprise a plurality of cam-in-slot mechanisms each operably connected to one of the adjustable racks. 
         [0013]    According to as second aspect, there is provided a transmission apparatus for use in a tape library. The transmission apparatus may comprise a tray for supporting a tape cartridge, a plurality of pinion gears operably connected to each another and rotatably attached to the tray, a plurality of vertically disposed racks for engagement by the plurality of pinion gears for rotational movement therealong, each of the plurality of vertically disposed racks being mounted on a frame, at least two of the plurality of vertically disposed racks being adjustable relative to their frames for adjusting an incline in the tray, and a plurality of cam-in-slot mechanisms each operably connected to one of the at least two of the plurality of vertically disposed racks. 
         [0014]    For all aspects, the slots of the cam-in-slot mechanisms may be located in the frames and the cams of the cam-in-slot mechanisms may be rotatably connected to the adjustable racks. The adjustable racks slideably engage the frames for vertical movement therealong. The vertically disposed racks may be arranged in a first pair oriented in a first direction and a second pair oriented in a second direction. The first pair may be oriented longitudinally outwardly; and the second pair may be oriented laterally outwardly. The plurality of racks may comprise four racks. Each rack may be disposed at, immediately adjacent, adjacent or near each one of four corners of the tray. 
         [0015]    According to a third aspect, there is provided tape library comprising the transmission apparatus of the first or second aspects. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    In order that the invention may be fully understood and readily put into practical effect there shall now be described by way of non-limitative example only exemplary embodiments, the description being with reference to the accompanying illustrative drawings. 
           [0017]    In the drawings: 
           [0018]      FIG. 1  is a perspective schematic view of an exemplary embodiment of a transmission apparatus; 
           [0019]      FIG. 2  is a schematic close-up view of a rack-and-pinion gear pair; 
           [0020]      FIG. 3  is a schematic plan view of the transmission apparatus of  FIG. 1 ; 
           [0021]      FIG. 4  is a schematic close-up view of a bevel gear train; 
           [0022]      FIG. 5  is another perspective schematic view of the transmission apparatus of  FIG. 1 ; 
           [0023]      FIG. 6  is a a schematic front view of a frame comprising a cam-in-slot mechanism operably connected to a rack; 
           [0024]      FIG. 7  is a schematic rear view of the frame of  FIG. 6 ; and 
           [0025]      FIG. 8  is a schematic close-up view of the cam-in-slot mechanism of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0026]      FIGS. 1 to 3  show a preferred embodiment of a transmission apparatus  10  that is largely symmetrical about a horizontal axis X. The transmission apparatus  10  includes a rectangular tray  12  for transporting a tape cartridge and a rack  14 -and-pinion gear  16  pair at, immediately adjacent, adjacent or near each of the four corners A, B, C, D of the tray  12 . 
         [0027]    Each rack  14  is vertically mounted to and supported by a frame  18 . Each frame  18  constitutes a corner post. They may be of any suitable material or shape provided they are substantially rigid, given their purpose. As shown, each frame  18  is a U-shaped channel member with the racks  14  being securely mounted to a web  19  of each frame  18 . Each frame  18  is securely attached to a base  17 . The four racks  14  are for being engaged by the four pinion gears  16  rotatably therealong, as shown in  FIG. 2 . 
         [0028]    The pinion gears  16  are mounted on a laterally extending drive shaft  20 , and the remote ends of longitudinally extending driven shafts  22 . The pinion gears  16  are located on the drive shaft  20  at, immediately adjacent, adjacent or near each end of the drive shaft  20 . The drive shaft  20  is driven by a motor  24  mounted to the tray  12 . The drive shaft  20  pinion gears  16  are for direct engagement with the relevant racks  14 C and  14 D. For this, the racks  14 C and  14 D are oriented with the gears facing longitudinally outwardly in the direction of the X axis, as is shown in  FIG. 2 . 
         [0029]    Between the drive shaft  20  and each of the driven shafts  22  is a bevel gear train  28 , shown in close-up in  FIG. 4 . A first bevel gear  42  is mounted to each end of the drive shaft  20  intermediate but adjacent the pinion gears  16 . The first bevel gears  42  are also spaced from the pinion gears  16 . A second bevel gear  44  is mounted to the driven shafts at the ends of the driven shafts  22 . As the two bevel gears  42 ,  44  mesh, rotation of the lateral drive shaft  20  results in simultaneous rotation of the longitudinal driven shafts  22 . 
         [0030]    Shafts  20 ,  22  are rotatably mounted to tray  12  by bearing blocks  21  secured to the tray  12 , adjacent each end of the shafts  20 ,  22 . 
         [0031]    Each of the driven shafts  22  has a pinion gear  14  mounted thereon at, immediately adjacent, adjacent or near the end opposite or remote from the end to which the second bevel gear  44  is mounted. The pinion gears  16  at the remote ends of the driven shafts  22  engage the respective racks  14 A and  14 B. For this, the racks  14 A and  14 B are oriented differently to the racks  14 C and  14 D. The racks  14 A and  14 B both face laterally outwardly. In this way, rotation of the drive shaft  20  results in simultaneous rotation of all four pinion gears  16 . As the four pinion gears  16  simultaneous rotate along their respective racks  14 , vertical movement of the tray  12  is effected. By providing a rack  14 -and-pinion gear  16  pair at each of the four corners A, B, C, D of the tray  12 , and having the four rack  14 -and-pinion gear  16  pairs identical, precise and controlled vertical movement of the tray may be achieved. This makes the transmission apparatus  10  suitable for use with reduced slot sizes since the tray  12  may be precisely positioned. 
         [0032]    A further embodiment of the transmission apparatus  10  is depicted in  FIG. 5  which shows the frames  18  mounted onto a base plate  26 . In this embodiment, the rack  14  at corner D is fixed to its frame  18 . The racks  14  at corners A, B, C and D are adjustable with respect to their frames  18 . However, a rack  14  at one corner only may not be adjustable, if required or desired. 
         [0033]      FIGS. 6 to 8  show close-ups of a cam-in-slot mechanism for adjusting a rack  14  with respect to a frame  18  in order to adjust or tune the incline of the tray  12 . This allows the tray  12  to be levelled at all the four corners A, B, C and D so that the tray  12  is level at all four corners. This would normally mean that the tray  12  is perpendicular to the four frames  18 . Allowing the incline of the tray  12  to be adjusted or tuned provides improved positioning accuracy of the tray  12  across the entire length or breadth of the tape library. 
         [0034]    As shown in  FIGS. 6 to 8 , the adjustable rack  14  is slidably attached to the frame  18  via vertically oriented pin-in-slot connections  70 . In a preferred embodiment, pins  71  of the pin-in-slot connections  70  are provided on the rack  14  while the slots  72  are provided in the frame  18 . For each pin-in-slot connection  70 , two pins  71  may be provided to engage one slot  72  for added rigidity. The adjustable rack  14  is thus constrained to move only vertically with respect to the frame  18 , as indicated by the arrow in  FIG. 7 , and the extent of the vertical movement is limited by the vertical height of the slots  72 . 
         [0035]    A cam lever  50  is rotatably attached to the adjustable rack  14  through a cam slot  80  in the web  19  of the frame  18 . In this way, the cam lever  50  is on one side of the web  19  of the frame  18  while the rack  14  is on the other side of the web  19  of the frame  18 . The cam lever  50  has a centre of rotation  60  and a guide pin  62  that is constrained to move within a curved guide slot  64 . The cam lever  50  is rotatably attached to the rack  14  at its centre of rotation  60 . 
         [0036]    Also attached to the cam lever  50  is a cam  82 . The cam  82  is a simple circular disc that has its geometrical centre offset from the centre of rotation  60  of the cam lever  50 , as shown in  FIG. 8  (for clarity, cam lever  50  has been rendered transparent). The offset cam  82  acts against a side  84  of the cam slot  80 , such that rotation of the cam lever  50  (as shown by the curved arrow in  FIG. 6 ) results in vertical movement of the rack (as shown by the arrow in  FIG. 7 ). In this way, each of the corners A, B, C of the tray  12  may be adjusted for height with respect to corner D in order to tune the incline of the tray  12 . Also, this is to allow for adjustment if the pinion gear  16  engages incorrect teeth of the rack  14 , thereby creating a misalignment. A sensor (such as a laser meter or measurement gauge commonly used in printers to control pen-to-paper spacing) may be provided to measure the incline of the tray and allow fine adjustments so as to achieve maximum “horizontalness” of the tray  12  with respect to a vertical axis. 
         [0037]    In all the embodiments, the various mechanical parts of the transmission apparatus  10  such as the rack  14 -and-pinion gear  16  pairs, the drive shafts  20 ,  22  and the bevel gear trains  28  are preferably inexpensive, off-the-shelf components. This not only reduces costs, but may also reduce the weight of the transmission apparatus  10 . 
         [0038]    Whilst there has been described in the foregoing description exemplary embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations in details of design, construction and/or operation may be made without departing from the present invention. For example, the motor may be directly connected to one of the driven shafts  22  instead of to the drive shaft  20 . The rack  14 -and-pinion gear  16  pairs may be located at the sides instead of at the corners of the tray  12 , so that only three pairs  14 ,  16  are provided at three sides of the tray  12 , leaving one side of the tray  12  open for loading and unloading tape cartridges. The adjustable racks  14  may engage the frames by providing appropriate tongue-in-groove adaptations on the racks  14  and the frames  18  instead of the pin-in-slot connections  70 .

Technology Category: y