Patent Publication Number: US-2007108206-A1

Title: Cartridge

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a cartridge for a changer structured such that a plurality of information recording mediums are accommodated within a cartridge case or a plurality of trays each loading the information recording medium are accommodated within the cartridge, and more particularly to an assembling structure of the cartridge case.  
      2. Description of Related Art  
      In conventional, there has been proposed a cartridge for a changer structured such that a plurality of trays loading information recording mediums are accommodated within one cartridge case, and used in a state of being detachably installed to a drive apparatus (refer, for example, to patent document 1 (JP-A-2000-40324)).  
      In the cartridge described in the patent document 1, since the cartridge case is integrally and inseparably formed, however, it is necessary to be provided with an energizing means, a lock bar and the like for stably holding a tray within the cartridge case, it is impossible to actually form the cartridge case as an integrally inseparable structure or it is extremely hard to produce it. Accordingly, with regard to the cartridge for the changer, it is required to develop an assembling structure of a cartridge case which is provided with a necessary function and is easily assembled.  
      In this case, as a conventionally known general assembling structure of a cartridge case for accommodating information mediums, there are a thread fastening system (for example, a 5-inch MO cartridge) in which a cartridge case is constituted by an upper case and a lower case, and a plurality of positions at least including four corners of the upper case and the lowercase are fastened by screws, an ultrasonic depositing system (for example, a DVD-RAM cartridge) in which abutting faces of the upper case and the lower case are deposited by an ultrasonic wave, and a snap connecting system (for example, an LTO tape cartridge) in which locking pawls  102  are provided in a hanging manner at four corner portions of an upper case  101 , engagement holes  104  capable of engaging the locking pawls  102  therewith are formed at four corner portions of a lower case  103 , and the upper case and the lower case are integrated by snap fitting the locking pawls  102  with the engagement holes  104 , as shown in  FIG. 36 . These assembling structures can be applied to the cartridge for the changer. In this case, in accordance with the thread fastening system, it is possible to firmly connect the upper case and the lower case and it is possible to obtain a cartridge case having a high strength. Further, in accordance with the ultrasonic depositing system and the snap connecting system, since a special space for joining the upper case and the lower case is not required in an opening portion side of the cartridge case, it is possible to make the cartridge relatively compact in comparison with the case of employing the thread fastening system.  
      However, the cartridge for the changer takes the information recording medium or the tray in which the information recording medium is loaded in and out through an opening portion. Accordingly, in the case that the thread fastening system is employed as the assembling structure of the cartridge case, and the thread fastening is executed in the portion closer to the opening portion than the center portion of the cartridge case, a width of the opening portion is limited by a space for the thread fastening. As a result, there is generated a problem that a width of the cartridge case is necessarily enlarged.  
      On the other hand, since the cartridge for the changer has a large size and a heavy weight, a high strength is required. However, it is impossible to connect the upper case and the lower case at a high strength in accordance with the ultrasonic deposition, and the connection between the upper case and the lower case is easily broken at a time when an impact force is applied by a drop or the like. As a result, there is generated a problem that the information recording medium tends to be damaged.  
      Further, in the case that the snap connecting system is employed as the assembling structure of the cartridge case, it is necessary that the locking pawl  102  is provided in a hanging manner in the abutting face of a peripheral wall  101   a  constituting the upper case  101  to the lower case  103 , a thin portion  103  for inside inserting the locking pawl  102  is formed in the abutting face of a peripheral wall  103   a  constituting the lower case  103  to the upper case  101 , and an engagement hole  104  of the locking pawl  102  is provided in the thin portion  103   b , as is apparent from  FIG. 36 . Accordingly, the thicknesses of the peripheral walls  101   a  and  103   a  become large. As a result, there is generated a problem that a flat surface size of the cartridge case is enlarged.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention is made by solving the problems of the prior arts mentioned above, and an object of the present invention is to provide a cartridge for a changer having a compact size and a high strength.  
      In order to achieve the object mentioned above, in accordance with the present invention, there is provided a cartridge comprising:  
      a cartridge case having an opening portion;  
      a plurality of information recording mediums or a plurality of trays each loading the information recording medium which are accommodated within the cartridge case so as to freely come in and out through the opening portion; and  
      the plurality of information mediums or trays being held by guide ribs which are formed in an inner side surface of the cartridge case in parallel to each other at a predetermined pitch,  
      wherein the cartridge case is constituted by an upper case, a lower case and right and left side plates having the guide ribs, the respective members are integrally connected in a portion closer to the opening portion than a center portion of the cartridge in accordance with a fitting operation utilizing a fitting means formed between the upper case and upper ends of the right and left side plates, and between the lower case and lower ends of the right and left side plates, and the respective members are integrally connected in a depth side than the center portion of the cartridge case in accordance with a thread fastening.  
      As mentioned above, since the cartridge case is constituted by the upper case, the lower case and the right and left side plates, and the respective members are integrally connected in the portion closer to the opening portion than the center portion of the cartridge in accordance with the fitting operation utilizing the fitting means formed between the upper case and the upper ends of the right and left side plates, and between the lower case and the lower ends of the right and left side plates, it is possible to integrally connect the respective members without arranging any member for connection such as a screw or the like in a front face of the opening portion. Accordingly, it is possible to achieve a downsizing of the cartridge case. Further, since the respective members are integrally connected in the depth side than the center portion of the cartridge case in accordance with the thread fastening, it is possible to firmly connect the respective members. Accordingly, it is possible to achieve a high strength of the cartridge case.  
      Further, in accordance with the present invention, in the cartridge having the structure mentioned above, the upper case has a top plate constituting an upper face of the cartridge case, the lower case has a bottom plate constituting a lower surface of the cartridge case, a top plate side fitting means having a thinner thickness than a thickness of the top plate is formed in end surfaces in both right and left sides of the top plate, a bottom plate side fitting means having a thinner thickness than a thickness of the bottom plate is formed in end surfaces in both right and left sides of the bottom plate, and a side plate side fitting means fitting to the top plate side fitting means and the bottom plate side fitting means is formed predetermined portions of the right and left side plates, and the upper case, the lower case and the right and left side plates are integrally connected in accordance with a slide fitting.  
      As mentioned above, since the top plate side fitting means of the bottom plate side fitting means having the thinner thickness than the thickness of the top plate or the bottom plate is formed in the end faces in both the right and left sides of the top plate constituting the upper case and the bottom plate constituting the lower case, the side plate side fitting means fitting to the top plate side fitting means or the bottom plate side fitting means is formed in the predetermined portions of the side plates, and the upper case, the lower case and the right and left side plates are integrally connected by slide fitting the top plate side fitting means to the side plate side fitting means and slide fitting the bottom plate side fitting means to the side plate side fitting means, the respective members can be firmly connected without increasing the thicknesses of the upper case, the lower case and the side plates as is different from the case of employing the snap connecting system. Accordingly, it is possible to achieve a downsizing of the cartridge case.  
      Further, in accordance with the present invention, in the cartridge having the structure mentioned above, the structure is made such that a shutter opening and closing the opening portion is provided in a front end portion of the cartridge case.  
      As mentioned above, since the shutter for opening and closing the opening portion is provided in the front end portion of the cartridge case, it is possible to prevent a foreign material from making an intrusion into the cartridge case. Accordingly, it is possible to improve a long-term keeping quality of the information recording medium accommodated within the cartridge case.  
      In accordance with one aspect of the present invention, since the cartridge case is constituted by the upper case, the lower case and the right and left side plates, the respective members are integrally connected in the portion closer to the opening portion than the center portion of the cartridge in accordance with the fitting operation utilizing the fitting means formed between the upper case and the right and left side plates, and between the lower case and the right and left side plates, and the respective members are integrally connected in the depth side than the center portion of the cartridge case in accordance with the thread fastening, it is possible to integrally connect the respective members without arranging any member for connection such as a screw or the like in a front face of the opening portion, wherein it is possible to achieve a downsizing of the cartridge case, and it is possible to firmly connect the respective members, whereby it is possible to achieve a high strength of the cartridge case. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       FIG. 1  is a perspective view of a cartridge at a time when it is not used;  
       FIG. 2  is a perspective view of the cartridge at a time when it is used;  
       FIG. 3  is an exploded perspective view of the cartridge;  
       FIG. 4  is a plan view of an upper case;  
       FIG. 5  is a front elevational view as seen from a front end side of the upper case;  
       FIG. 6  is a bottom elevational view of the upper case;  
       FIG. 7  is a plan view of a lower case;  
       FIG. 8  is a front elevational view as seen from a front end side of the lower case;  
       FIG. 9  is a bottom elevational view of the lower case;  
       FIG. 10  is a front elevational view as seen from an inner surface side of a left side plate;  
       FIG. 11  is a side elevational view as seen from a front end side of the left side plate;  
       FIG. 12  is a side elevational view as seen from a rear end side of the left side plate;  
       FIG. 13  is a plan view of the left side plate;  
       FIG. 14  is a bottom elevational view of the left side plate;  
       FIG. 15  is a front elevational view as seen from an inner surface side of a right side plate;  
       FIG. 16  is a side elevational view as seen from a rear end side of the right side plate;  
       FIG. 17  is a side elevational view as seen from a front end side of the right side plate;  
       FIG. 18  is a plan view of the right side plate;  
       FIG. 19  is a bottom elevational view of the right side plate;  
       FIG. 20  is a perspective view showing an assembling method of the left side plate and the right side plate with respect to an assembled body of the upper case and the lower case;  
       FIG. 21  is a cross sectional view of a main portion showing an assembled state of the left side plate with respect to the upper case and the lower case and an accommodated state of a disc tray within a cartridge case;  
       FIG. 22  is a perspective view of a disc tray;  
       FIG. 23  is an explanatory view showing a dimensional relation between the disc tray and a guide rib;  
       FIG. 24  is a cross sectional view of a portion A in  FIG. 22 ;  
       FIG. 25  is a cross sectional view of a portion B in  FIG. 22 ;  
       FIG. 26  is a cross sectional view as seen from a flat surface direction showing the accommodated state of the disc tray within the cartridge case;  
       FIG. 27  is a cross sectional view of a main portion as seen from a front end direction showing the accommodated state of the disc tray within the cartridge case;  
       FIG. 28  is a cross sectional view of a main portion showing an effect of an inverse slope portion;  
       FIG. 29  is a front elevational view as seen from a lower side of a shutter;  
       FIG. 30  is a front elevational view of a shutter lock member;  
       FIG. 31  is a side elevational view of the shutter lock member;  
       FIG. 32  is an explanatory view showing an opening and closing operation of the shutter;  
       FIG. 33  is an explanatory view showing the opening and closing operation of the shutter;  
       FIG. 34  is a perspective view of a disc tray in accordance with the other embodiment;  
       FIG. 35  is an enlarged view of a portion C in  FIG. 34 ;  
       FIG. 36  is a cross sectional view of a main portion explaining a snap connecting system between the upper case and the lower case; and  
       FIG. 37  is a perspective vie of a cartridge using a cartridge case integrally formed in a state in which the upper and lower cases are connected. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      A description will be given below of an embodiment in which an information recording medium accommodated in a cartridge in accordance with the present invention is constituted by in information recording disc.  
      As shown in FIGS.  1  to  3 , a disc cartridge in accordance with the present embodiment is constituted by a box-shaped cartridge case  1  having an opening portion  1   a  in one side surface, a shutter  2  attached to the cartridge case  1  so as to freely swirl and opening and closing the opening portion  1   a , a shutter lock member  3 , a plurality of disc trays  4  accommodated so as to freely come in and out an inner portion of the cartridge case  1  through the opening portion  1   a , a plurality of information recording discs  5  mounted on the respective disc trays  4  one by one, a management memory apparatus set within the cartridge case  1 , a first shutter spring  7  provided in a tensional manner between the cartridge case  1  and the shutter  2 , and a second shutter spring  8  provided in a tensional manner between the cartridge case  1  and the shutter lock member  3 .  
      The cartridge case  1  is formed as a box shape of a desired magnitude having the opening portion  1   a  in one side by an upper case  11 , a lower case  12 , a left side plate  13  and a right side plate  14 , as shown in  FIG. 3 . Each of the members  11 ,  12 ,  13  and  14  is constituted by an injection molded produce of a plastic.  
      The upper case  11  is formed as a shape structuring an upper half of the cartridge case  1  by an approximately quadrangular top plate  21  having step portions  21   a  in both right and left sides of a front end portion (a side in which the opening portion  1   a  is formed), and partition walls  22  hanged down from both right and left side lines except a forward portion than the step portions  21   a  of the top plate  21  and a rear line and having a fixed height, as shown in FIGS.  4  to  6 . A fitting projection  23  for fitting front end upper portions of the side plates  13  and  14  are provided in an end surface portion in a front side of the step portion  21   a  of the top plate  21  so as to be protruded outward. On the other hand, two ribs  24  and  25  are formed in parallel in an inner surface of the top plate  21  so as to be spaced at an interval capable of inserting the left side plate  13  and an interval capable of inserting the right side plate  14  respectively with respect to the partition walls  22  hanged down from both the right and left side lines of the top plate  21 , and projections  26  and  27  for temporarily fastening the respective side plates  13  and  14  are provided in a protruding manner in portions facing to rear ends of the respective ribs  24  and  25 . Further, a boss  28  having a thread hole is provided in a protruding manner in a rear end corner portion of the inner surface of the top plate  21 . Further, a setting portion  29  of the management memory apparatus  6  is formed in an inner surface of the partition wall  22  hanged down from the rear line of the top plate  21 .  
      The lower case  12  is formed as a shape structuring a lower half of the cartridge case  1  by an approximately quadrangular bottom plate  31  having step portions  31   a  in both right and left sides of a front end portion, and partition walls  32  risen up from both right and left side lines except a forward portion than the step portions  31   a  of the bottom plate  31  and a rear line and having a fixed height, as shown in FIGS.  7  to  9 . A fitting projection  33  for fitting front end lower portions of the side plates  13  and  14  are provided in an end surface portion in a front side of the step portion  31   a  of the bottom plate  31  so as to be protruded outward. On the other hand, two ribs  34  and  35  are formed in parallel in an inner surface of the bottom plate  31  so as to correspond to the ribs  24  and  25  formed in the upper case  11 , and first bosses  36  and  37  for screwing the respective side plates  13  and  14  are provided in a protruding manner in portions facing to rear ends of the respective ribs  34  and  35 . Further, a second boss  38  is provided in a protruding manner in a portion corresponding to the boss  28  formed in the upper case  11  in an inner surface of the bottom plate  31 . Further, a setting portion  39  of the management memory apparatus  6  is formed in a portion corresponding to the setting portion  29  formed in the upper case  11  in the partition wall  32  hanged down from the rear line of the bottom plate  31 .  
      The upper case  11  and the lower case  12  are assembled in the box shape by confronting a lower line of the partition wall  22  and an upper line of the partition wall  32  with each other, and fastening the screw inserted into the thread hole formed in the boss  28  to the second boss  38 .  
      The left side plate  13  is formed as a shape and a magnitude which can be inserted into a space constituted by the top plate  21 , the partition wall  22  and the rib  24  of the upper case  11 , and the bottom plate  31 , the partition wall  32  and the rib  34  of the lower case  12 , as shown in FIGS.  10  to  14 . A plurality of (seven in the present embodiment) guide ribs  41  are formed in the inner surface of the left side plate  13  so as to be in parallel to a direction from a front end side to a rear end side, and a mounting hole  42  of the shutter  2  is provided in a portion having no guide rib  41 . On the contrary, a spring peg projection  42   a  locking one end of the first shutter spring  7  is provided in a protruding manner near a mounting hole  42  in an outer surface of the left side plate  13 . Further, in upper and lower portions close to the front end of the left side plate  13 , there are formed fitting concave portions  43  and  44  for fitting the fitting projection  23  formed in the upper case  11  and the fitting projection  33  formed in the lower case  12 . Further, an erroneous insertion preventing portion  45  of the disc tray  4  is formed in a rear end portion of the left side plate  13 , a locking pawl  46  engaged with the temporarily fitting projection  26  formed in the inner surface of the upper case  11  is formed in an upper portion of the erroneous insertion preventing portion, and a thread hole  47  fastened to the thread hole of the first boss  36  formed in the lower case  12  by the screw is provided in a lower portion thereof.  
      The right side plate  14  is formed as a shape and a magnitude which can be inserted into a space constituted by the top plate  21 , the partition wall  22  and the rib  25  of the upper case  11 , and the bottom plate  31 , the partition wall  32  and the rib  35  of the lower case  12 , as shown in FIGS.  15  to  19 . The same number of guide ribs  51  as the guide ribs  41  are formed at the corresponding positions to the guide ribs  41  formed in the inner surface of the left side plate  13 , in the inner surface of the right side plate  14 , and a mounting hole  52  of the shutter  2  is provided in a portion having no guide rib  51 . On the contrary, an outer surface of the right side plate  14  is provided with a mounting projection  52   a  of the shutter lock member  3  and a spring peg projection  52   a  locking one end of the second shutter spring  8  in accordance with a predetermined arrangement. Further, in upper and lower portions close to the front end of the right side plate  14 , there are formed fitting concave portions  53  and  54  for fitting the fitting projection  23  formed in the upper case  11  and the fitting projection  33  formed in the lower case  12 . Further, an erroneous insertion preventing portion  55  of the disc tray  4  is formed in a rear end portion of the right side plate  14 , a locking pawl  56  engaged with the temporarily fitting projection  27  formed in the inner surface of the upper case  11  is formed in an upper portion of the erroneous insertion preventing portion, and a thread hole  57  fastened to the thread hole of the first boss  37  formed in the lower case  12  by the screw is provided in a lower portion thereof. In this case, reference numeral  58  in the drawing denotes a tray locking portion for stably holding the disc tray  4  accommodated within the cartridge case  1 . The tray locking portion  58  is constituted by an elastic piece  58   a  formed by cutting three sides of the right side plate  14 , and a locking pawl  58   b  formed in a leading end portion of the elastic piece  58   a , and is structured such that the locking pawl  58   b  is arranged within a tray inserting space formed between the guide ribs  51 . In this case, the right side plate  14  is formed such that an entire length thereof is slightly longer than the left side plate  13 .  
      The left side plate  13  is inserted from the opening portion  1   a  along an inner surface of a left side of the integrally assembled upper case  11  and lower case  12 , as shown in  FIG. 20 . Accordingly, as shown in  FIG. 21 , the fitting projection  23  formed in the upper case  11  and the fitting projection  33  formed in the lower case  12  are slidably fitted to the fitting concave portions  43  and  44  formed in the upper and lower portions close to the front end of the left side plate  13 , and the upper case  11 , the lower case  12  and the left side plate  13  are integrally connected in the portion closer to the opening portion  1   a  than the center portion of the cartridge case  1 . If the left side plate  13  is inserted to a predetermined position, the locking pawl  46  formed in the rear end portion of the left side plate  13  is engaged with the temporarily fitting projection  26  formed in the inner surface of the upper case  11 , and the formed position of the thread hole  47  provided in the rear end portion of the left side plate  13  and the formed position of the first boss  36  provided in the lower case  12  are automatically coincided. Accordingly, the left side plate  13  can be fixed to the lower case  12  by inserting the screw inserted to the thread hole of the first boss  36  into the thread hole  47  so as to fasten.  
      On the other hand, the right side plate  14  is inserted from the opening portion  1   a  along the inner surface of the right side of the integrally assembled upper case  11  and lower case  12 , as shown in  FIG. 20 . Accordingly, the fitting projection  23  formed in the upper case  11  and the fitting projection  33  formed in the lower case  12  are slidably fitted respectively into the fitting concave portions  53  and  54  formed in the upper and lower portions close to the front end of the right side plate  13 , and the upper case  11 , the lower case  12  and the right side plate  14  are integrally connected in the portion closer to the opening portion  1   a  than the center portion of the cartridge case  1 . If the right side plate  14  is inserted to a predetermined position, the locking pawl  56  formed in the rear end portion of the right side plate  14  is engaged with the temporarily fixing projection  27  formed in the inner surface of the upper case  11 , and the formed position of the thread hole  57  provided in the rear end portion of the right side plate  14  and the formed position of the first boss  37  provided in the lower case  12  are automatically coincided. Accordingly, it is possible to fix the right side plate  14  to the lower case  12  by inserting the screw inserted to the thread hole of the first boss  37  into the thread hole  57  so as to fasten. Therefore, the assembly of the cartridge  1  is finished.  
      The disc tray  4  is formed in an approximately quadrangular shape capable of being accommodated within the cartridge case  1  in an outer shape, as shown in  FIG. 22 . Further, in the disc tray  4 , a hook  4   a  for engaging a tray operating arm provided in a disc drive apparatus (not shown) is formed in a right corner portion in a front end, and erroneous insertion preventing notches  4   b  and  4   c  having different lengths are formed in both left and right corner portions in a rear end. A difference of the lengths of the notches  4   b  and  4   c  is set to a difference of the lengths of the left side plate  13  and the right side plate  14 . The disc tray  4  in accordance with the present embodiment has a thick portion  62  in which a disc accommodating concave portion  61  is formed, and a thin portion  63  held by the guide ribs  41  and  51  formed in the left and right side plates  13  and  14 , and an approximately triangular engagement concave portion  4   d  for engaging a locking pawl  58   b  formed in the right side plate  14  is formed in a rear portion of the right thin portion  63 . The disc tray in accordance with the present embodiment is also formed by an injection molded produce of a plastic.  
      As shown in  FIG. 23 , a thickness h 1  of the thick portion  62  is set to a value (h 1 &lt;h 5 +h 6 ) which is slightly smaller than a total of a dimension h 5  of a gap between two guide ribs  41  and  51  arranged adjacently with each other and a thickness h 6  of one guide ribs  41  and  51 . Further, the thickness h 2  of the thin portion  63  is set to a value (h 2 &lt;h 5 ) which is slightly smaller than the dimension of the gap between two guide ribs  41  and  51  arranged adjacently with each other. The value (h 5 +h 6 −h 1 ) and the value (h 5 −h 2 ) are approximately set while taking into consideration a clearance necessary for smoothly sliding the disc tray  4 , a deformation with age and the like. In this case, the value h 5  is set to a value which is equal to or slightly larger than the thickness of the information recording disc  5 , and the value h 6  is set while taking into consideration a strength and a formability of the guide ribs  41  and  51 . Further, a magnitude of a step h 3  formed between an upper surface of the thick portion  62  and an upper surface of the thin portion  63  and a magnitude of a step h 4  formed between a lower surface of the thick portion  62  and a lower surface of the thin portion  63  are set in such a manner that the information recording disc  5  is arranged within the gap between two guide rigs  41  and  51  arranged adjacently with each other, while taking into consideration the thickness of the information recording disc  5  and a thickness of a disc holding portion (mentioned below) formed in the disc accommodating concave portion  61 .  
      The disc accommodating concave portion  61  is formed by a circular peripheral wall  64  structured such that a diameter is larger than a diameter of the information recording disc  5  and a depth is larger than the thickness of the information recording disc  5 , and a rib-shaped disc holding portion  65  protruded inward from a lower side of the peripheral wall  64 , and a part of the disc holding portion  65  is provided with a notch  66  reaching the thin portion  63 . A protruding amount s of the disc holding portion  65  from the peripheral wall  64  is set such that the disc holding portion  65  is brought into contact only with an outer peripheral non-recording region of the information recording disc  5 . In a portion of the peripheral wall  64  corresponding to the notch  66 , there is formed an inverse slope portion  67  in which a diameter of the peripheral wall  64  is increased toward the disc holding portion  65  side from the opening surface side of the peripheral wall  64 , as a drop preventing portion of the information recording disc  5 , as shown in  FIG. 24 . On the contrary, in the other portions, it is formed in a direction in which a slope of the peripheral wall  64  corresponds to a draft angle necessary for injection molding the disc tray  4 , that is, in a direction in which the diameter of the peripheral wall  64  becomes smaller toward the disc holding portion  65  side from the opening surface side of the peripheral wall  64 , as shown in  FIG. 25 .  
      The disc tray  4  is accommodated within the cartridge case  1  in a state in which the information recording disc  5  is accommodated within the disc accommodating concave portion  61 , as shown in  FIG. 26 . In the case that the disc tray  4  is accommodated within the cartridge case  1  so as to be directed to a correct direction, the erroneous insertion preventing portion  45  formed in the left side plate  13  and the erroneous insertion preventing portion  55  formed in the right side plate  14  can be inserted to the end portions of the notches  4   b  and  4   c  formed in the rear end of the disc tray  4 , respectively. Accordingly, it is possible to insert the disc tray  4  to a predetermined position within the cartridge case  1  so as to be accommodated. Further, in this case, since the locking pawl  58   b  formed in the right side plate  14  is engaged with the engagement concave portion n 4   d  formed in the disc tray  4 , it is possible to prevent the disc tray  4  from carelessly falling away from the cartridge case  1 . On the contrary, in the case that the disc tray  4  is accommodated within the cartridge case  1  so as to be directed to an erroneous direction, the corner portion of the disc tray  4  is brought into contact with the erroneous insertion preventing portion  45  formed in the left side plate  13 . Accordingly, it is possible to automatically prevent a further insertion. The disc tray  4  inserted into the cartridge case  1  toward the correct direction is mounted on each of the guide ribs  41  and  51  in which the thin portion  63  is formed in the cartridge case  1 , as shown in  FIG. 27 , and an outer peripheral portion of the information recording disc  5  is arranged within the gap between two guide ribs  41  and  51  arranged adjacently with each other. Accordingly, it is possible to achieve a reduction of the width of the cartridge case  1 .  
      In the disc tray  4  in accordance with the present embodiment, since the inverse slope portions  67  are formed in the corresponding portion to the notch  66  in the peripheral wall  65 , in the case that the cartridge case  1  is vertically arranged in a state in which each of the inverse slope portions  67  is directed in a vertical direction, an outer peripheral edge portion of the information recording disc  5  is brought into contact with the inverse slope portion  67  in a lower side, as shown in  FIG. 28 . Then, there is generated a moment M rotating the information recording disc  5  in a direction in which the information recording disc  5  is closely attached to the disc holding portion  65  of the disc tray  4 . Accordingly, it is possible to prevent the information recording disc  5  from falling away from the disc accommodating concave portion  61 , and it is possible to improve a practicability and a general-purpose property of the disc cartridge.  
      The information recording disc  5  is structured such that a desired thin film including an information recording film is formed on one surface or both surfaces of a disc substrate. As the information recording film, it is possible to form a known optional information recording film, for example, a magnetic recording film, an optical recording film, a magneto-optic disc or the like.  
      The management memory apparatus  6  records an attribute and the like of the information recording disc  5  accommodated within the disc cartridge, can conveniently use the disc cartridge, and can employ a radio communication tag (RFID) and the like. The management memory apparatus  6  is set within the setting portions  29  and  39  formed in the rear end portions of the upper case  11  and the lower case  12 .  
      The shutter  2  is constituted by an upper surface portion  71  covering an upper surface of the cartridge case  1 , a front surface portion  72  covering a front surface of the cartridge case  1 , and a side surface portion  73  covering a side surface of the cartridge case  1 , as shown in  FIGS. 29, 32  and  33 . In an inner surface of the side surface portion  73 , there is formed in a protruding manner a support shaft  74  rotatably inserted to the mounting holes  42  and  52  provided in the left side plate  13  and the right side plate  14  so as to face to each other. Further, a spring peg projection  75  locking one end of the first shutter spring  7  is provided in a protruding manner in an inner surface of the side surface portion  73  in the left side, and an engagement projection  76  for detachably engaging the shutter lock member  3  mentioned below is provided in a protruding manner in an inner surface of the side surface portion  73  in the right side. The shutter  2  in accordance with the present embodiment is attached to the front surface portion of the cartridge case  1  so as to freely swirl by inserting the support shaft  74  to the mounting holes  42  and  52 . The first shutter spring  7  is provided in a tensional manner between the spring peg projection  75  and the spring peg projection  42   a  provided in a protruding manner in the outer surface of the left side plate  13 , and always energizes the shutter  2  in an opening direction. The shutter  2  in accordance with the present embodiment is also formed by the injection molded product of the plastic.  
      The shutter lock member  3  is formed by a plate-like main body portion  81 , an operating portion risen up outward from a front end lower portion of the main body portion  81 , an approximately rod-like shutter locking portion  83  protruded to a front side of the main body portion  81  from an upper line of the main body portion  81 , and an engagement portion  84  of the second shutter spring  8  protruded to a rear side from a rear end of the main body portion  81 , as shown in  FIGS. 30 and 31 . In the main body portion  81 , there are formed an L-shaped mounting hole  85 , and an engagement portion  86  of the mounting projection  52   a  formed in the right side plate  14 . The shutter lock member  3  in accordance with the present embodiment is attached to the right side plate  14  so as to be movable forward and backward as shown in  FIGS. 32 and 33 , by inserting the mounting projection  52   a  formed in the right side plate  14  to a vertical line portion  85   a  of the L-shaped mounting hole  85 , thereafter moving the mounting projection  52   a  to a horizontal line portion  85   b  of the L-shaped mounting hole  85  and engaging a leading end portion thereof with the engagement portion  86 . The second shutter spring  8  is provided in a tensional manner between the spring peg projection  52   b  formed in the right side plate  14  and the engagement portion  84  formed in the shutter lock member  3 , and always energizes the shutter lock member  3  to the opening portion  1   a  side. The shutter lock member  3  in accordance with the present embodiment is also formed by the injection molded product of the plastic.  
      When it is not used, the shutter lock member  3  is moved to the opening portion  1   a  side of the cartridge case  1  by the elastic force of the second shutter spring  8 , as shown in  FIG. 32 , and the shutter locking portion  83  is engaged with the engagement projection  76  formed in the shutter  2 . Accordingly, the shutter  2  is held in a closed state against the elastic force of the first shutter spring  7 , and it is possible to prevent a foreign material or the like from making an intrusion into the cartridge case  1  from the opening portion  1   a.    
      If the disc cartridge is installed to the disc drive apparatus (not shown), a canceling portion provided within the disc drive apparatus pushes the operating portion  82  of the shutter lock member  3  to a rear side, as shown in  FIG. 33 , thereby moving the shutter lock member  3  to the rear side of the cartridge case  1  against the elastic force of the second shutter spring  8 . Accordingly, the engagement between the engagement projection  76  formed in the shutter  2  and the shutter locking portion  83  formed in the shutter lock member  3  is cancelled, and the shutter  2  comes to an open state by the elastic force of the first shutter spring  7 . It is possible to take out the disc tray  4  from the inner side of the cartridge case  1  through the opening portion  1   a  and it is possible to accommodate the disc tray  4  within the cartridge case  1  from the disc drive apparatus.  
      Since the disc cartridge in accordance with the present embodiment is structured by forming the thick portion  62  in which the disc accommodating concave portion  61  is formed and the thin portion  63  held by the guide ribs  41  and  51  formed in the cartridge case  1  in the disc tray  4 , and making the difference between the thickness of the thick portion  62  and the thickness of the thin portion  63  smaller than the thickness of the guide ribs  41  and  51 , it is possible to improve an accommodating density of the disc tray  4  in comparison with the case that the thin portion  63  is not formed in the disc tray  4 . Further, since the step is formed between the upper surface of the thick portion  62  and the upper surface of the thin portion  63 , and between the lower surface of the thick portion  62  and the lower surface of the thin portion  63 , it is possible to arrange the information recording disc  5  at an intermediate position between two guide ribs  41  and  51 , it is possible to prevent collation between the guide ribs  41  and  51  and the information recording disc  5 , and it is possible to improve a storage stability of the information recording disc  5 . Further, since the depth of the disc accommodating concave portion  61  is made larger than the thickness of the information recording disc  5 , the other disc tray  4  is hard to be brought into contact with the recording surface of the information recording disc  5  mounted in one disc tray  4 , and the storage stability of the information recording disc  5  can be improved from this point. Further, since the notch  66  reaching the thin portion  63  is provided in a part of the disc holding portion  65 , it is possible to arrange the leading end portions of the guide ribs  41  and  51  within the notch  66 , and it is possible to achieve a downsizing on the basis of the reduction of the width of the cartridge.  
      In this case, in the embodiment mentioned above, the inverse slope portion  67  is formed as the drop preventing portion of the information recording disc  5 , however, the scope of the present invention is not limited to this, but one or a plurality of (four in an example in  FIG. 34 ) drop preventing projection  91  may be formed in a part of the peripheral wall  64  constituting the disc accommodating concave portion  61 , as shown in  FIGS. 34 and 35 . As mentioned above, in the case that the drop preventing projection  91  is formed as the drop preventing portion in the peripheral wall  64 , it is possible to prevent the information recording disc  5  from falling away from the disc  4  not only in the case that the cartridge case  1  is vertically arranged in a state in which the notch  66  is directed in the vertical direction, but also in the case that the cartridge case  1  is vertically arranged in a state in which the notch  66  is directed in a lateral direction. Accordingly, it is possible to further improve the practicability and the general-purpose property of this kind of disc cartridge.  
      Further, in the embodiment mentioned above, the description is given by exemplifying the disc cartridge in which the disc tray  4  mounting the information recording disc  5  thereon is held by the guide ribs  41  an d 51  formed in the side plates  13  and  14 , however, the scope of the present invention is not limited to this. The present invention can be applied to a disc cartridge in which the outer peripheral non-recording region of the information recording disc  5  is directly held by the guide ribs  41  and  51 .  
      Further, in the embodiment mentioned above, the description is given by exemplifying the cartridge in which the upper and lower cases are separately structured, however, the present invention can be similarly applied to a structure in which the upper and lower cases are integrally formed in a state of being connected, as shown in  FIG. 37 .