BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a tape cartridge recording/playback apparatus and particularly to a tape cartridge misloading prevention mechanism that is arranged at a mail slot for preventing the misleading of a tape cartridge. 
         [0003]    2. Description of the Related Art 
         [0004]    A typical tape cartridge autoloader includes a tape cartridge picker in the center, a mail slot at the front side, a read/write tape drive at the rear side, and tape cartridge transport magazines disposed one at each lateral side. 
         [0005]    The tape cartridge picker is configured to transport a tape cartridge between the mail slot, the tape drive, and the tape cartridge transport magazines. A tape cartridge misleading prevention mechanism for preventing the misleading of the tape cartridge is arranged at the mail slot. 
         [0006]      FIG. 23  is a diagram showing a configuration of a tape cartridge misleading prevention mechanism according to the prior art. The illustrated tape cartridge misleading prevention mechanism is configured to prevent the misloading of a LTO (Linear Tape Open) tape cartridge (brand name). Pillars  2  and  3  are arranged at the lateral sides of an loading passage (mail slot)  1  of a LTO tape cartridge  10 , and a misleading prevention key  4  that is configured to rotate around an axis  5  is arranged at the pillar  2  on the X 2  side of the loading passage  1 . An end portion  4   a  of the tape cartridge misloading prevention key  4  is arranged to protrude toward the inner side of the loading passage  1 . 
         [0007]    The LTO tape cartridge  10  has an outer configuration as is shown in  FIG. 25A . As is shown in this drawing and in  FIG. 2 , a magnetic tape  11  is wound around a single reel  12  to be accommodated inside a cartridge main frame having a thickness of T 1 , and the magnetic tape  11  is arranged to be drawn out from the rear side. The LTO tape cartridge  10  includes a front face  13 , a rear face  14 , and side faces  15  and  16 . The side face  15  has a groove  15   a  for realizing engagement with a cartridge pin (not shown) of a tape cartridge picker  102  as is described in detail below. A triangular recessed step portion  17  is arranged at a corner portion of the upper face of the LTO tape cartridge  10  at which the rear face  14  and the side face  15  meet. The triangular recessed step portion  17  includes a wall portion  17   a  at its edge that extends in a direction slanted with respect to the Y 1 -Y 2  line. It is noted that the height of the upper surface of the triangular recessed step portion  17  with respect to the bottom face of the LTO tape cartridge  10  is denoted as h 1 . 
         [0008]    The end portion  4   a  of the misloading prevention key  4  is arranged at a height corresponding to the height h 1  of the triangular recessed step portion  17  of the LTO tape cartridge  10  inserted into the mail slot  1 . 
         [0009]    As is shown in  FIG. 24A , when the LTO tape cartridge  10  is loaded in a proper position, the triangular recessed step portion  17  fits underneath the misleading prevention key  4  so that the inner wall portion  17   a  of the triangular recessed step portion  17  comes into contact with the end portion  4   a  of the misleading prevention key  4  to rotate the misleading prevention key  4  in the counterclockwise direction and push the misloading prevention key  4  toward the X 2  side of the LTO tape cartridge loading passage  1 . The LTO tape cartridge  10  is loaded to reach a position indicated by the two-dotted lines in  FIG. 24A . 
         [0010]    When the LTO tape cartridge  10  is loaded in a position other than the proper position; for example, when the LTO tape cartridge  10  is loaded upside down as is shown in  FIG. 24B , the face  14  corresponding to the inserting direction front end of the LTO tape cartridge  10  comes into contact with the end portion  4   a  of the misleading prevention key  4  so that the LTO tape cartridge  10  is prevented from being inserted further. 
         [0011]    There are currently two types of tape cartridges on the market as tape cartridges adapted for in the tape cartridge autoloader as is described above. The LTO tape cartridge as is described above corresponds to one of the two types, and a DLT (Digital Linear Tape) tape cartridge (brand name) corresponds to the other type. Accordingly, a tape cartridge auto loader manufacturer has to manufacture a LTO tape cartridge autoloader adapted for the LTO tape cartridge and a DLT tape cartridge autoloader adapted for the DLT tape cartridge. 
         [0012]      FIG. 25B  is a diagram showing the outer configuration of the DLT tape cartridge  10 A, which includes a front face  13 A, a rear face  14 A, and side faces  15 A and  16 A. As is shown in this drawing and in  FIG. 15 , the DLT tape cartridge  10 A includes a recessed portion  18  arranged at the side face  16 A instead of the triangular recessed step portion  17  of the LTO tape cartridge  10 , and the DLT tape cartridge  10 A also includes a slit  19  connected to the recessed portion  18  that is arranged at a corner portion defined by the rear face  14 A and the side face  16 A, the slit  19  being positioned at a height that is slightly lower than the middle height position with respect to the thickness direction of the DLT tape cartridge  10 A. The side face  15 A includes a groove  15 Aa. The height from the bottom face of the DLT tape cartridge  10 A to the slit  19  is denoted as h 2 . It is noted that the height h 2  is not equal to the height h 1  shown in  FIG. 25B  (i.e., h 2 &lt;h 1 ). The recessed portion  18  includes an edge portion  18   a  at the Z 2  side and an edge portion  18   b  at the Y 2  side. 
         [0013]    In a case where the DLT tape cartridge  10 A is loaded into the tape cartridge autoloader with the tape cartridge misleading prevention mechanism as is shown in  FIG. 23 , the face at the inserting direction front end of the DLT tape cartridge  10 A comes into contact with the end portion  14   a  of the misleading prevention key  4  so that the DLT tape cartridge  10 A is prevented from being inserted further. 
         [0014]    As can be appreciated, a different tape cartridge misleading prevention mechanism has to be designed for the DLT tape cartridge autoloader. 
         [0015]    The misleading prevention mechanisms for the DLT tape cartridge and the LTO tape cartridge are preferably designed to have as many common features as possible in order to reduce manufacturing costs. 
       SUMMARY OF THE INVENTION 
       [0016]    Accordingly, embodiments of the present invention solve one or more of the above problems. 
         [0017]    In one embodiment of the present invention, a tape cartridge recording/playback apparatus is provided that includes: 
         [0018]    an inlet through which a tape cartridge is passed; and 
         [0019]    an interior portion into which the tape cartridge is inserted, the interior portion being configured to accommodate a plurality of the tape cartridges and including a tape cartridge misloading prevention key for preventing misleading of the tape cartridge, the tape cartridge misleading key being rotatably mounted at a location close to the inlet; wherein 
         [0020]    the tape cartridge misleading prevention key includes a protruding portion that is configured to block an inserting direction front end face of the tape cartridge when the tape cartridge is improperly inserted and prevent the tape cartridge from being inserted further, and a block portion that is configured to be pushed by the tape cartridge when the tape cartridge is properly inserted and displace the protruding portion to a position where the protruding portion does not block insertion of the tape cartridge. 
         [0021]    In another embodiment of the present invention, a tape cartridge recording/playback apparatus that receives a tape cartridge into an interior portion of the apparatus is provided, the apparatus including: 
         [0022]    a tape cartridge misleading prevention key that prevents misleading of the tape cartridge, the tape cartridge misleading key being rotatably mounted in the interior portion, the tape cartridge misleading prevention key including (i) a protruding portion that blocks an inserting direction front end face of the tape cartridge when the tape cartridge is improperly inserted and inhibits the tape cartridge from being inserted further, the protruding portion being in a first plane, and (ii) a block portion that is contacted by the tape cartridge when the tape cartridge is properly inserted, the block portion moving the protruding portion to a position where the protruding portion does not block insertion of the tape cartridge, the block portion being in a second plane that is different than the first plane. 
         [0023]    In another embodiment of the present invention a tape cartridge recording/playback apparatus that receives a tape cartridge into an interior portion of the apparatus is provided, the apparatus including: 
         [0024]    a tape cartridge misleading prevention key that prevents misleading of the tape cartridge, the tape cartridge misleading key being rotatably mounted in the interior portion, the tape cartridge misleading prevention key including (i) a protruding portion that blocks an inserting direction front end face of the tape cartridge when the tape cartridge is improperly inserted and inhibits the tape cartridge from being inserted further, and (ii) a block portion that is disposed at a different height from the protruding portion, that block portion being contacted by the tape cartridge when the tape cartridge is properly inserted, the block portion moving the protruding portion to a position where the protruding portion does not block insertion of the tape cartridge. 
         [0025]    According to one aspect of the present invention, by configuring the tape cartridge misleading prevention key to include a protruding portion as well as a block portion, misleading of a tape cartridge may be prevented while a tape cartridge that is properly inserted may pass where the tape cartridge misleading prevention key is located without being blocked by the protruding portion of the tape cartridge misloading prevention key. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a diagram illustrating prevention against misleading a LTO tape cartridge and a DLT tape cartridge in a LTO tape cartridge autoloader according to a first embodiment of the present invention and a DLT tape cartridge autoloader according to a second embodiment of the present invention; 
           [0027]      FIG. 2  is a perspective view of the LTO tape cartridge autoloader according to the first embodiment of the present invention with its cover removed; 
           [0028]      FIG. 3  is a side view of the interior of a tape cartridge transporting magazine of the LTO tape cartridge autoloader of  FIG. 1  viewed from the X 1  side; 
           [0029]      FIG. 4  is a diagram illustrating operations of a tape cartridge picker; 
           [0030]      FIG. 5  is a perspective view of a main module; 
           [0031]      FIGS. 6A and 6B  are diagrams showing the main module; 
           [0032]      FIG. 7  is an exploded perspective view of the main module; 
           [0033]      FIG. 8  is a perspective view of the main module viewed from the Y 1  side; 
           [0034]      FIG. 9  is a perspective view of a misleading prevention key for the LTO tape cartridge autoloader; 
           [0035]      FIG. 10  is an enlarged view of a tape cartridge misloading prevention mechanism; 
           [0036]      FIGS. 11A and 11B  are diagrams showing the misleading prevention key for the LTO tape cartridge autoloader, the LTO tape cartridge, and a mail slot; 
           [0037]    FIGS.  12 A 1 - 12 C 2  are diagrams illustrating operations of the misleading prevention key for the LTO tape cartridge autoloader in a case where the LTO tape cartridge is inserted in a proper position; 
           [0038]    FIGS.  13 A 1 - 13 C 3  are diagrams illustrating operations of the misloading prevention key for the LTO tape cartridge autoloader continued from FIGS.  12 A 1 - 12 C 2 ; 
           [0039]      FIGS. 14A-14E  are diagrams illustrating operations of the misleading prevention key for the LTO tape cartridge autoloader for preventing the misleading of a tape cartridge; 
           [0040]      FIG. 15  is a perspective view of the DLT tape cartridge according to the second embodiment of the present invention with its cover removed; 
           [0041]      FIG. 16  is an enlarged view of a tape cartridge misloading prevention mechanism for the DLT tape cartridge autoloader; 
           [0042]      FIG. 17  is a perspective view of a misleading prevention key for the DLT tape cartridge autoloader; 
           [0043]      FIGS. 18A and 18B  are diagrams showing the misleading prevention key for the DLT tape cartridge autoloader, the DLT tape cartridge, and a mail slot; 
           [0044]    FIGS.  19 A 1 - 19 C 2  are diagrams illustrating operations of the misleading prevention key for the DLT tape cartridge autoloader in a case where the DLT tape cartridge is inserted in a proper position; 
           [0045]    FIGS.  20 A 1 - 20 C 3  are diagrams illustrating operations of the misleading prevention key for the DLT tape cartridge autoloader continued from FIGS.  19 A 1 - 19 C 2 ; 
           [0046]      FIGS. 21A-21E  are diagrams illustrating operations of the misleading prevention key for the DLT tape cartridge autoloader for preventing the misleading of a tape cartridge; and 
           [0047]      FIGS. 22A and 22B  are diagrams showing mold apparatuses for molding the misleading prevention key for the LTO tape cartridge autoloader and the misleading prevention key for the DLT tape cartridge autoloader. 
           [0048]      FIG. 23  is a diagram showing a configuration of a tape cartridge misleading prevention mechanism according to the prior art; 
           [0049]      FIGS. 24A and 24B  are diagrams illustrating operations of the prior art tape cartridge misleading prevention mechanism of  FIG. 23  in exemplary cases of loading a tape cartridge; and 
           [0050]      FIGS. 25A and 25B  are diagrams showing prior art configurations of a LTO tape cartridge and a DLT tape cartridge, respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    In the following, preferred embodiments of the present invention are described with reference to the accompanying drawings. 
         [0052]    Specifically, descriptions of preferred embodiments of the present invention include the following: 
         [0053]    1. LTO Tape Cartridge  10  and DLT Tape Cartridge  10 A Misloading Prevention in LTO Tape Cartridge Autoloader  100  and DLT Tape Cartridge Autoloader  100 A ( FIG. 1 ) 
         [0054]    2. Configuration and Operations of LTO Tape Cartridge Autoloader  100  ( FIGS. 2 ,  3 , and  4 ) 
         [0055]    3. Configuration of Main Module  110  ( FIGS. 5 ,  6 ,  7 , and  8 ) 
         [0056]    4. Tape Cartridge Misloading Prevention Mechanism  500  ( FIGS. 9 ,  10 , and  11 ) 
         [0057]    5. Operations of Tape Cartridge Misloading Prevention Mechanism  500   
         [0058]    5-1. Case Where Tape Cartridge is Properly Inserted ( FIGS. 12 and 13 ) 
         [0059]    5-2. Other Cases ( FIG. 14 ) 
         [0060]    6. Configuration and Operations of DLT Tape Cartridge Autoloader  100 A ( FIG. 15 ) 
         [0061]    7. Tape Cartridge Misloading Prevention Mechanism  500 A ( FIGS. 16 ,  17 , and  18 ) 
         [0062]    8. Operations of Tape Cartridge Misloading Prevention Mechanism  500 A 
         [0063]    8-1. Case Where Tape Cartridge is Properly Inserted ( FIGS. 19 and 20 ) 
         [0064]    8-2. Other Cases ( FIG. 21 ) 
         [0065]    9. Method for Manufacturing Misloading Prevention Key  501  and Misloading Prevention Key  501 A ( FIG. 22 ) 
         [0066]    1. [LTO Tape Cartridge  10  and DLT Tape Cartridge  10 A Misloading Prevention in LTO Tape Cartridge Autoloader  100  and DLT Tape Cartridge Autoloader  100 A] ( FIG. 1 ) 
         [0067]    In  FIG. 1 , a LTO tape cartridge autoloader  100 , a DLT tape cartridge autoloader  100 A, a LTO tape cartridge  10 , and a DLT tape cartridge  10 A are shown. 
         [0068]    The LTO tape cartridge autoloader  100  includes a mail slot  107  as a loading slot at its front side, a tape cartridge picker  102  at the center, a LTO tape cartridge tape drive  101  at its rear portion, and a tape cartridge misleading prevention mechanism  500  arranged at the mail slot  107 . 
         [0069]    The DLT tape cartridge autoloader  100 A includes a mail slot  107  at its front side, a tape cartridge picker  102  at the center, a DLT tape cartridge tape drive  101 A at its rear portion, and a tape cartridge misleading prevention mechanism  500 A arranged at the mail slot  107 . 
         [0070]    In  FIG. 1 , the LTO tape cartridge  10  in a proper position, a LTO tape cartridge  10 -R positioned upside down, and a LTO tape cartridge  10 -S facing the wrong direction are shown. Also the DLT tape cartridge  10 A in a proper position, a DLT tape cartridge  10 A-R positioned upside down, and a DLT tape cartridge  10 A-S facing the wrong direction are shown. 
         [0071]    In the LTO tape cartridge autoloader  100 , the tape cartridge misloading prevention mechanism  500  is configured to enable the LTO tape cartridge  10  to pass through the mail slot  107  in the case where the LTO tape cartridge  10  is properly positioned upon being inserted into the mail slot  107 . In other cases, namely, in cases where the LTO tape cartridge  10  is not properly positioned (e.g., LTO tape cartridges  10 -R and  10 -S), or in a case where the DLT tape cartridge  10 A is inserted, the tape cartridge misleading prevention mechanism  500  is configured to reject the inserted tape cartridge. It is noted that in  FIG. 1 , the mark ◯ denotes acceptance of the inserted tape cartridge, and the mark × denotes rejection of the inserted tape cartridge. 
         [0072]    In the DLT tape cartridge loader  100 A, tape cartridge misloading prevention mechanism  500 A is configured to enable the DLT tape cartridge  10 A to pass through the mail slot  107  in the case where the DLT tape cartridge  10 A is properly positioned upon being inserted into the mail slot  107 . In other cases, namely, in cases where the DLT tape cartridge  10 A is not properly positioned (e.g., DLT tape cartridges  10 A-R and  10 A-S), or in a case where the LTO tape cartridge  10  is inserted, the tape cartridge misloading prevention mechanism  500 A is configured to reject the inserted tape cartridge. 
         [0073]    2. [Configuration and Operations of LTO Tape Cartridge Autoloader  100 ] ( FIGS. 2 ,  3 , and  4 ) 
         [0074]      FIG. 2  is a diagram showing the LTO tape cartridge autoloader  100  according to a first embodiment of the present invention with its upper cover removed.  FIG. 3  is a diagram showing a configuration of the LTO tape cartridge autoloader  100  with its side cover removed. It is noted that in these drawings, directions X 1 -X 2  represent width direction, direction Y 1 -Y 2  represent depth directions, and directions Z 1 -Z 2  represent height directions. 
         [0075]    In one embodiment, the LTO tape cartridge autoloader  100  generally comprises a metal frame  190 , a control panel  105  and a mail slot  107  both arranged on a front panel, a main module  110  including a tape cartridge picker  102  at a position opposing the mail slot  107 , a LTO tape cartridge read/write tape drive  101  disposed at the Y 1  side of the main module  110 , and one or more tape cartridge transport magazines  103  and  104  (for example, two tape cartridge transport magazines  103  and  104  are shown in the embodiment illustrated in  FIG. 2 ), which in this embodiment, are disposed one at the X 1  side and the X 2  side of the main module  110 . For example, the tape cartridge transport magazines  103  and  104  can be inserted toward the Y 1  side from the front panel side and removably attached on opposing sides of the frame  190 . In an alternative embodiment, the tape cartridge transport magazines  103 ,  104  can be positioned to have a different orientation relative to one another and/or to the main module  110 . In one embodiment, the LTO tape cartridge autoloader  100  can be mounted in a rack by fixing four corners of the frame  190  to poles of the rack, for example. 
         [0076]    As is shown in  FIG. 3 , the tape cartridge transport magazines  103  and  104  each have plural containers  401 , and are configured to accommodate the LTO media cartridges  10  in the containers  401  with the front faces  13  facing toward the tape cartridge picker  102 . The tape cartridge transport magazines  103  and  104  are also configured to transport the media cartridges  10  along a racetrack path elongated in the Y 1 -Y 2  direction. 
         [0077]    The LTO tape cartridge tape drive  101  is operable to read and/or write data from or to the magnetic tape  11  pulled out from the loaded LTO tape cartridge  10 . The LTO tape cartridge tape drive  101  includes a tape cartridge eject mechanism (not shown). 
         [0078]    As is shown in  FIG. 4 , the tape cartridge picker  102  is configured to transport the LTO tape cartridge  10  onto or off of a turntable  140  for operations such as loading the LTO tape cartridge  10  inserted through the mail slot  107  into the LTO tape cartridge tape drive  101 , retrieving the LTO tape cartridge  10  from the tape cartridge transport magazines  103  and  104  to load the LTO tape cartridge  10  onto the LTO tape cartridge tape drive  101 r retrieving the LTO tape cartridge  10  from the LTO tape cartridge tape drive  101  to return the LTO tape cartridge  10  to the tape cartridge transport magazines  103  and  104 , and ejecting the LTO tape cartridge  10  through the mail slot  107 . The tape cartridge picker  102  is also configured to rotate the turntable  140  by a predetermined rotational interval, such as by approximately 90-degree increments, although the rotational interval can vary depending upon the design requirements of the LTO tape cartridge autoloader  100 . The tape cartridge picker  102  can also lift/lower the turntable  140  as necessary. When the turntable  140  is rotated, the orientation of the LTO tape cartridge  10  is changed. 
         [0079]    When an ejection command is issued, the LTO tape cartridge  10  is transported by a tape cartridge linear transporting mechanism  170  (described below) through the mail slot  107  until its front face  13  side protrudes out of the mail slot  107 . Then, an operator may get hold of the LTO tape cartridge  10  and pull this LTO tape cartridge  10  out of the LTO tape cartridge autoloader  100 . 
         [0080]    3. [Configuration of Main Module  110 ] ( FIGS. 5 ,  6 ,  7 , and  8 ) 
         [0081]      FIG. 5  is a perspective view of the main module  110 ;  FIG. 6A  is a front view of the main module  110 ; and  FIG. 6B  is a cross-sectional view of the main module  110 .  FIG. 7  is an exploded view of the main module  110 .  FIG. 8  is a perspective view of the main module  110 , viewed from the Y 1  side. 
         [0082]    In this embodiment, the main module  110  includes a base  120 . The main module  110  also includes the tape cartridge picker  102 , a tape cartridge transport magazine drive motor module  330 , a mail slot module  340 , a rotation transmitting channel forming apparatus  300 , and the tape cartridge misleading prevention mechanism  500 . The mail slot module  340  includes a frame  341  and the mail slot  107  arranged inside the frame  341 . The tape cartridge picker  102  can occupy a large part of the base  120 . The base  120  includes an extension  120   a  extending at the Y 2  side of the tape cartridge picker  102 . A drive shaft unit  301  and a tape cartridge transport magazine drive motor module  330  are disposed on the extension  120   a.  For example, the mail slot module  340  can be mounted on the upper side of the magazine drive motor module  330 . As is shown in  FIGS. 6A and 6B , in one embodiment, the mail slot  107  may be disposed at the same height as the turntable  140 . 
         [0083]    The base  120  at the Y 2  side of the tape cartridge picker  102  includes a tape cartridge guide hollow pillar  121  at the X 1  side, a tape cartridge guide hollow pillar  122  at the X 2  side, and a tape cartridge guide rail  123  at the Z 2  side. The tape cartridge guide hollow pillars  121 ,  122 , and the tape cartridge guide rail  123  are disposed along the outline of the mail slot  107  viewed from the Y 2  side, and are configured to guide the LTO tape cartridge  10  that is being transported through the mail slot  107  and into the tape cartridge picker  102 . 
         [0084]    4. [Tape Cartridge Misloading Prevention Mechanism  500 ] ( FIGS. 9 ,  10 , and  11 ) 
         [0085]    The tape cartridge misleading prevention mechanism  500  is arranged at the tape cartridge guide hollow pillar  122 , and comprises a misleading prevention key  501  as is shown in  FIG. 9 . In one embodiment, the misleading prevention key  501  is supported within the tape cartridge guide hollow pillar  122  as is shown in  FIGS. 5 ,  10 ,  11 A, and  11 B, and is applied a force in the counterclockwise direction by a spring  510 . 
         [0086]    As is shown in  FIG. 9 , the misleading prevention key  501  includes a center tube  502 , an arm portion  503  extending from the center tube  502 , a protruding plate  504  at the tip of the arm portion  503 , and a triangular prism block  508 . The protruding plate  504  includes an end face  504   a  at its Y 2  side. The triangular prism block  508  includes a first slanted face  505 , a second slanted face  507 , and a corner portion  506 . The corner portion  506  is formed by the first slanted face  505  and the second slanted face  507 . 
         [0087]    In the present embodiment, a stationary shaft  125  is arranged to extend from a bottom plate  124  to protrude in the Z 1  direction within the tape cartridge guide hollow pillar  122 . 
         [0088]    The center tube  502  includes a portion  502   a  corresponding to the arm portion  503 , a portion  502   b  having a length L 1  that protrudes from the arm portion  503  in the Z 2  direction, and a portion  502   c  having a length L 2  that protrudes from the arm portion  503  in the Z 1  direction. The length L 2  is relatively short, and in one embodiment, the length L 1  is arranged to be at least five times greater than the length L 2 . Alternatively, the length L 1  can be less than or equal to five times greater than the length L 2 . 
         [0089]    The misloading prevention key  501  is rotatably mounted by realizing engagement of the center tube  502  and the stationary shaft  125  arranged within the tape cartridge guide hollow pillar  122 . In this case, the bottom end of the center tube  502  comes into contact with the bottom plate  124 , and the protruding plate  504  is disposed at a height H 1  from the top face of the tape cartridge guide rail  123  (see  FIG. 11B ). It is noted that in the present embodiment, the height H 1  corresponds to the height h 1  of the recessed step portion  17  from the bottom face of the LTO tape cartridge  10  shown in  FIG. 25A . 
         [0090]    The arm portion  503  is arranged to extend in the Y 2  direction. The protruding plate  504  and the triangular prism block  508  are arranged to protrude into the mail slot  107  from the X 2  side. In this case, the end face  504   a  of the protruding plate  504  is arranged to be perpendicular to the Y 1 -Y 2  line; that is, the end face  504   a  is arranged to be perpendicular to the tape cartridge inserting direction. 
         [0091]    As is shown in  FIG. 11B , the triangular prism block  508  is disposed at the Z 2  side of the protruding plate  504 . As is shown in  FIG. 11A , the first slanted face  505  extends from the end face  504   a  of the protruding plate  504  in a direction slightly slanted from the Y 1  direction. The extending direction of the first slanted face  505  slants toward the X 1  direction as it extends in the Y 1  direction. The corner portion  506  is disposed at one end of the first slanted face  505 , and is arranged to protrude in the X 1  direction. Similarly, as is shown in  FIG. 11A , the second slanted face  507  is disposed toward the Y 2  side with respect to the protruding plate  504 , and is arranged to extend in a direction slightly slanted toward the X 1  direction from the Y 2  direction. 
         [0092]    The protruding plate  504  is configured such that its end face  504   a  blocks the inserting direction front end face of a tape cartridge that is erroneously inserted. 
         [0093]    The first slanted face  505  and the corner portion  506  of the triangular block  508  are configured to be pushed by a tape cartridge that is properly inserted so that the protruding plate  504  may be displaced to a position where it may not obstruct the insertion of the tape cartridge. 
         [0094]    The second slanted face  507  of the triangular prism block  508  is configured to be pushed by a tape cartridge that is being ejected so that the protruding plate  504  may be displaced to a position where it may not obstruct the ejection of the tape cartridge. 
         [0095]    5. [Operations of Tape Cartridge Misloading Prevention Mechanism  500 ] 
         [0096]    5-1. [Case Where Tape Cartridge is Properly Inserted] ( FIGS. 12 and 13 ) 
         [0097]      FIGS. 12 and 13  are diagrams illustrating a case in which the LTO tape cartridge  10  is inserted in a proper position with its rear face  14  facing forward in the inserting direction. It is noted that FIGS.  12 A 1 ,  12 A 2 , and FIGS.  13 A 1 - 13 A 3  are perspective views of the LTO tape cartridge and the misleading prevention key  501 . FIGS.  12 B 1 ,  12 B 2 , and FIGS.  13 B 1 - 13 B 3  are corresponding plan views from the Z 1  side; and FIGS.  12 C 1 ,  12 C 2 , and FIGS.  13 C 1 - 13 C 3  are corresponding plan views from the Z 2  side. 
         [0098]    FIGS.  12 A 1 ,  12 B 1 , and  12 C 1  are diagrams showing the LTO tape cartridge  10  being inserted into the mail slot  107  in the Y 1  direction to face the misloading prevention key  501 . Specifically, in these drawings, the recessed step portion  17  is facing the protruding plate  504 . 
         [0099]    When the LTO tape cartridge  10  is inserted further into the mail slot  107 , the recessed step portion  17  engages the lower side of the protruding plate  504  as is shown in FIGS.  12 A 2  and  12 B 2 . Also, in this case, the X 2  side edge of the rear face  14  of the LTO tape cartridge  10  comes into contact with the first slanted face  505  of the triangular prism block  508  as is shown in FIG.  12 C 2 . 
         [0100]    When the LTO tape cartridge  10  is inserted further into the mail slot  107 , the first slanted face  505  is pushed in the X 2  direction as is shown in FIGS.  13 A 1 ,  13 B 1 , and  13 C 1 . In this case, the side face  16  of the LTO tape cartridge  10  comes into contact with the corner portion  506  at the edge of the first slanted face  505 , and the misleading prevention key  501  is rotated in the clockwise direction viewed from the Z 1  side against the force of the spring  510  (illustrated in  FIG. 10 ) as is shown in FIG.  13 C 1 . Also, the protruding plate  504  is displaced toward the X 2  direction to be positioned on the X 2  side of the recessed step portion  17  as is shown in FIG.  13 B 1 . In this way, the LTO tape cartridge  10  may be inserted through the mail slot  107  without hitting the protruding plate  504  as is shown in FIGS.  13 A 2 ,  13 B 2 , and  13 C 2  to pass through the misleading prevention key  501  as is shown in FIGS.  13 A 3 ,  13 B 3 , and  13 C 3 . 
         [0101]    As can be appreciated from the above descriptions, when the LTO tape cartridge  10  is inserted in a proper position and orientation, the LTO tape cartridge  10  may be inserted through the mail slot  107  without being blocked by the misloading prevention key  501  and pass the lateral side of the misloading prevention key  501 . 
         [0102]    After the LTO tape cartridge  10  passes the misleading prevention key  501 , the misloading prevention key  501  is reverted to its original position by the force of the spring  510 , and the second slanted face  507  of the triangular prism block  508  faces the front face  13  of the LTO tape cartridge  10 . During ejection, the LTO tape cartridge  10  pushes the second slanted face  507  to displace the triangular prism block  508  in the X 2  direction and is transported in the Y 1  direction through the mail slot  107 . 
         [0103]    5-2. [Other Cases] ( FIG. 14 ) 
         [0104]      FIGS. 14A-E  illustrate non-exclusive examples of cases other than that illustrated in  FIGS. 12 and 13 . 
         [0105]    Specifically,  FIG. 14A  illustrates a case of inserting the LTO tape cartridge  10 -R that is positioned upside down. In this case, the rear face  14  of the LTO tape cartridge  10 -R hits the end face  504   a  of the protruding plate  504  so that the LTO tape cartridge  10 -R is prevented from being inserted further into the mail slot  107 . 
         [0106]      FIG. 14B  illustrates a case of inserting the LTO tape cartridge  10 -S that is oriented such that its side face  15  corresponds to the inserting direction front end. In this case, the side face  15  of the LTO tape cartridge  10 -S hits the protruding plate  504  so that the LTO tape cartridge  10 -S is prevented from being inserted further into the mail slot  107 . 
         [0107]    The LTO tape cartridge  10 -S is similarly prevented from being inserted through the mail slot  107  in a case where its side face  16  or its front face  13  corresponds to the inserting direction front end in which case the side face  16  or the front face  13  hits the protruding plate  504 . 
         [0108]      FIG. 14C  illustrates a case of inserting the DLT tape cartridge  10 A. In this case, since the slit  19  is positioned toward the Z 2  side with respect to the protruding plate  504 , the rear face  14 A of the DLT tape cartridge  10 A hits the protruding plate  504  so that the DLT tape cartridge  10 A is prevented from being inserted further into the mail slot  107 . 
         [0109]      FIG. 14D  illustrates a case of inserting the DLT tape cartridge  10 A-R that is positioned upside down. In this case, the rear face  14 A of the DLT tape cartridge  10 A-R hits the protruding plate  504  so that the DLT tape cartridge  10 A-R is prevented from being inserted further into the mail slot  107 . 
         [0110]      FIG. 14E  illustrates a case of inserting the DLT tape cartridge  10 A-S that is oriented such that its side face  15 A corresponds to the inserting direction front end. In this case, the side face  15 A of the DLT tape cartridge  10 A-S hits the protruding plate  504  so that the DLT tape cartridge  10 A-S is prevented from being inserted further into the mail slot  107 . 
         [0111]    The DLT tape cartridge  10 A-S is similarly prevented from being inserted through the mail slot  107  in a case where its side face  16 A or its front face  13 A corresponds to the inserting direction front end in which case the side face  16 A or the front face  13 A hits the protruding plate  504 . 
         [0112]    As can be appreciated from the above descriptions, although the specific configuration of the misleading prevention key  501  can vary from those illustrated in the Figures, the misleading prevention key  501  can be configured to enable the LTO tape cartridge  10  to pass through the mail slot  107  only when the LTO tape cartridge  10  is inserted in the proper position and orientation, and thwart tape cartridge insertion in other cases. 
         [0113]    6. [Configuration and Operations of DLT Tape Cartridge Autoloader  100 A] ( FIG. 15 ) 
         [0114]      FIG. 15  is a diagram showing the DLT tape cartridge autoloader  100 A according to a second embodiment of the present invention. The DLT tape cartridge autoloader  100 A is adapted for the DLT tape cartridge  10 A. Since the size of the DLT tape cartridge  10 A is substantially the same as the size of the LTO tape cartridge  10 , the DLT tape cartridge autoloader  100 A is substantially identical to the LTO tape cartridge autoloader  100  except for its main module  110 A. 
         [0115]    The main module  110 A includes a tape cartridge misleading prevention mechanism  500 A that is different from the tape cartridge misleading prevention mechanism  500  of the main module  100 . It is noted that other parts of the main module  110 A are identical to those of the main module  100 . 
         [0116]    7. [Tape Cartridge Misloading Prevention Mechanism  500 A] ( FIGS. 16 ,  17 , and  18 ) 
         [0117]      FIG. 16  is a diagram showing the tape cartridge misleading prevention mechanism  500 A. The tape cartridge misleading prevention mechanism  500 A is adapted for the DLT tape cartridge  10 A, and includes a misloading prevention key  501 A as is shown in  FIG. 17 . 
         [0118]    The misleading prevention key  501 A includes a center tube  502 A that differs from the center tube  502  of the misleading prevention key  501 . Other parts of the misleading prevention key  501 A are identical to the misleading prevention key  501 . Specifically, the misloading prevention key  501 A includes the arm portion  503 , the protruding plate  504 , and the triangular prism block  508  as is described above. 
         [0119]    The center tube  502 A has a configuration that is reciprocal to the configuration of the center tube  102  of the misleading prevention key  501  with respect to the X-Y plane at the center of the arm portion  502 . That is, in this embodiment, the center tube  502 A includes a portion  502 Ab protruding from the arm portion  503  in the Z 2  direction that is arranged to have a relatively short length L 2 , and a portion  502 Ac protruding from the arm portion  503  in the Z 1  direction that has a length L 1  that is substantially longer than the length L 2 . 
         [0120]    The misleading prevention key  501 A is rotatably mounted by realizing engagement of the center tube  502 A and the stationary shaft  125  arranged within the tape cartridge guide hollow pillar  122 . In this case, the bottom end of the center tube  502 A comes into contact with the bottom plate  124 , and the protruding plate  504  is disposed at a height H 2  from the top face of the tape cartridge guide rail  123  (see  FIG. 18B ). It is noted that in the present embodiment, the height H 2  corresponds to the height h 2  of the slit  19  from the bottom face of the DLT tape cartridge  10 A shown in  FIG. 25B . 
         [0121]    As is shown in  FIG. 18B , the height H 10  of the bottom plate  124  of the base  120  with respect to the top face of the tape cartridge guide rail  123  is adjusted such that the protruding plate  504  may be positioned at the height H 1  in a case where the misleading prevention key  501  is arranged at the tape cartridge guide hollow pillar  122 , and the protruding plate  504  may be positioned at the height H 2  in a case where the misloading prevention key  501 A is arranged at the tape cartridge guide hollow pillar  122 . 
         [0122]    8. [Operations of Tape Cartridge Misloading Prevention Mechanism  500 A] 
         [0123]    8-1. [Case Where Tape Cartridge is Properly Inserted] ( FIGS. 19 and 20 ) 
         [0124]      FIGS. 19 and 20  are diagrams illustrating a case in which the DLT tape cartridge  10 A is inserted in a proper position with its rear face  14 A facing forward in the inserting direction. It is noted that FIGS.  19 A 1 ,  19 A 2 , and FIGS.  20 A 1 - 20 A 3  are perspective views of the LTO tape cartridge and the misleading prevention key  501 A. FIGS.  19 B 1 ,  19 B 2 , and FIGS.  20 B 1 - 20 B 3  are corresponding plan views from the Z 1  side; and FIGS.  19 C 1 ,  19 C 2 , and FIGS.  20 C 1 - 20 C 3  are corresponding plan views from the Z 2  side. 
         [0125]    FIGS.  19 A 1 ,  19 B 1 , and  19 C 1  are diagrams showing the LTO tape cartridge  10  being inserted into the mail slot  107  in the Y 1  direction to face the misloading prevention key  501 . Specifically, in these drawings, the slit  19  is facing the protruding plate  504 . 
         [0126]    When the DLT tape cartridge  10 A is inserted further into the mail slot  107 , the slit  19  engages the protruding plate  504  as is shown in FIGS.  19 A 2  and  19 B 2 , and the protruding plate  504  passes through the slit  19  to enter the recessed portion  18  as is shown in FIGS.  20 A 1 ,  20 B 1 , and  20 C 1 . 
         [0127]    Also, as is shown in FIG.  19 C 2 , the X 2  side edge of the rear face  14 A of the DLT tape cartridge  10 A comes into contact with the first slanted face  505  of the triangular prism block  508  so that the triangular prism block  508  is pushed in the X 2  direction. When the DLT tape cartridge  10 A is inserted further into the mail slot  107 , the edge portion  18   a  of the side face  16 A of the DLT tape cartridge  10 A comes into contact with the corner portion  506 , and misleading prevention key  501  is rotated in the clockwise direction viewed from the Z 1  side against the force of the spring  510  (illustrated in  FIG. 16 ) and retained in this position as is shown in FIG.  20 C 1 . In this case, the protruding plate  504  is displaced toward the X 2  direction to be positioned at the X 2  side of the recessed portion  18  as is shown in FIG.  20 B 1 . 
         [0128]    When the DLT tape cartridge  10 A is inserted further into the mail slot  107 , the edge portion  18   b  closes in on the protruding plate  504 . At this point, the edge portion  18   a  is still in contact with the corner portion  506  of the triangular prism block  508 . Thus, the edge portion  18   b  passes the protruding plate  504  without hitting the end face  504   a  as is shown in FIGS.  20 A 2 ,  20 B 2 , and  20 C 2 . Further, the DLT tape cartridge  10 A may be inserted past the misleading prevention key  501 A as is shown in FIGS.  20 A 3 ,  20 B 3 , and  20 C 3 . 
         [0129]    As can be appreciated from the above descriptions, when the DLT tape cartridge  10 A is inserted in a proper position and orientation, the DLT tape cartridge  10 A may be inserted through the mail slot  107  without being blocked by the misleading prevention key  501 A and pass the lateral side of the misleading prevention key  501 A. 
         [0130]    After the DLT tape cartridge  10 A passes the misleading prevention key  501 A, the misleading prevention key  501 A is reverted to its original position by the force of the spring  510 , and the second slanted face  507  of the triangular prism block  508  faces the front face  13  of the DLT tape cartridge  10 A. During ejection, the DLT tape cartridge  10  pushes the second slanted face  507  to displace the triangular prism block  508  in the X 2  direction and is transported in the Y 1  direction through the mail slot  107 . 
         [0131]    8-2. [Other Cases] ( FIG. 21 ) 
         [0132]      FIGS. 21A-E  illustrate non-exclusive embodiments of cases other than that illustrated in  FIGS. 19 and 20 . 
         [0133]    Specifically,  FIG. 21A  illustrates a case of inserting the DLT tape cartridge  10 A-R that is positioned upside down. In this case, the rear face  14 A of the DLT tape cartridge  10 A-R hits the end face  504   a  of the protruding plate  504  so that the DLT tape cartridge  10 A-R is prevented from being inserted further into the mail slot  107 . 
         [0134]      FIG. 21B  illustrates a case of inserting the DLT tape cartridge  10 A-S that is oriented such that its side face  15 A corresponds to the inserting direction front end. In this case, the side face  15 A of the DLT tape cartridge  10 A-S hits the protruding plate  504  so that the DLT tape cartridge  10 A-S is prevented from being inserted further into the mail slot  107 . 
         [0135]    The DLT tape cartridge  10 A-S is similarly prevented from being inserted through the mail slot  107  in a case where its side face  16 A or its front face  13 A corresponds to the inserting direction front end in which case the side face  16 A or the front face  13 A hits the protruding plate  504 . 
         [0136]      FIG. 21C  illustrates a case of inserting the LTO tape cartridge  10 . In this case, since the triangular recessed step portion  17  is positioned toward the Z 1  side with respect to the protruding plate  504 , the rear face  14  of the LTO tape cartridge  10  hits the protruding plate  504  so that the LTO tape cartridge  10  is prevented from being inserted further into the mail slot  107 . 
         [0137]      FIG. 21D  illustrates a case of inserting the LTO tape cartridge  10 -R that is positioned upside down. In this case, the rear face  14  of the LTO tape cartridge  10 -R hits the protruding plate  504  so that the LTO tape cartridge  10 -R is prevented from being inserted further into the mail slot  107 . 
         [0138]      FIG. 21E  illustrates a case of inserting the DLT tape cartridge  10 -S that is oriented such that its side face  15  corresponds to the inserting direction front end. In this case, the side face  15  of the LTO tape cartridge  10 -S hits the protruding plate  504  so that the LTO tape cartridge  10 -S is prevented from being inserted further into the mail slot  107 . 
         [0139]    The LTO tape cartridge  10 -S is similarly prevented from being inserted through the mail slot  107  in a case where its side face  16  or its front face  13  corresponds to the inserting direction front end in which case the side face  16  or the front face  13  hits the protruding plate  504 . 
         [0140]    As can be appreciated from the above descriptions, although the specific configuration of the misloading prevention key  501 A can vary from those illustrated in the Figures, the misleading prevention key  501 A can be configured to enable the DLT tape cartridge  10 A to pass through the mail slot  107  only when the DLT tape cartridge  10  is inserted in the proper position and orientation, and thwart tape cartridge insertion in other cases. 
         [0141]    9. Method for Manufacturing Misloading Prevention Key  501  and Misloading Prevention Key  501 A ( FIG. 22 ) 
         [0142]      FIG. 22A  is a diagram showing a mold apparatus  600  for molding the misleading prevention key  501 . The mold apparatus  600  includes upper and lower molds  601  and  602  for molding the parts of the misloading prevention key  501  other than the center tube  502  (i.e., the arm portion  503 , the protruding plate  504 , and the first and second slanted faces  505  and  507 ) and upper and lower molds  603  and  604  for molding the center tube  502 . The misleading prevention key  501  is molded using this mold apparatus  600 . 
         [0143]      FIG. 22B  is a diagram showing a mold apparatus  600 A for molding the misloading prevention key  501 A. The mold apparatus  600 A includes components identical to those of the mold apparatus  600  but has the mold  603  and the mold  604  arranged at reverse positions with respect to their positions within the mold apparatus  600 . 
         [0144]    As can be appreciated from the above descriptions, the misleading prevention key  501  and the misleading prevention key  501 A may be molded using the same molds so that manufacturing costs may be reduced compared to a case in which molds dedicated for each of the misleading prevention keys  501  and  501 A are used. 
         [0145]    It is noted that a tape cartridge misleading prevention mechanism according to an embodiment of the present invention is not limited to application within a tape cartridge autoloader as is described above, and may also be used in other applications such as a tape cartridge library. 
         [0146]    Although the present invention is shown and described with respect to certain non-exclusive embodiments, it is obvious that equivalents and modifications may occur to others skilled in the art upon reading and understanding the specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the appended claims. 
         [0147]    The present application is based on and claims the benefit of the earlier filing date of Japanese Patent Application No. 2006-198417 filed on Jul. 20, 2006, the entire contents of which are hereby incorporated by reference.
A tape cartridge recording/playback apparatus that receives a tape cartridge into an interior portion of the apparatus is disclosed. The apparatus includes a tape cartridge misleading prevention key that prevents misloading of the tape cartridge. The tape cartridge misleading key is rotatably mounted in the interior portion of the apparatus and includes (i) a protruding portion that blocks an inserting direction front end face of the tape cartridge when the tape cartridge is improperly inserted and inhibits the tape cartridge from being inserted further, the protruding portion being in a first plane, and (ii) a block portion that is contacted by the tape cartridge when the tape cartridge is properly inserted, the block portion moving the protruding portion to a position where the protruding portion does not block insertion of the tape cartridge, the block portion being in a second plane that is different than the first plane.