Abstract:
A frame and upper and lower shells made of metal plates covering the top and bottom of the frame constitute a flat housing. A disk cartridge rotatably houses a disk serving as a recording medium in the flat housing. Disassembly of the disk cartridge is facilitated. An engaging protrusion  25  is provided on at least one of the side of the frame  22 . The engaging protrusion can freely oscillate in and out from the surface and is elastically urged in a direction the engaging protrusion  25  protrudes from the surface. At the same time, an engaging aperture  23   c  which engages with the engaging protrusion  25  is formed on at least one of the upper and lower shells  23  and  24.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a small disk cartridge which rotatably houses a disk serving as a recording medium in a flat housing constituted of a frame and upper and lower shells made of metal plates covering the top and bottom of the frame. More particularly, the present invention relates to an assembly structure of the housing.  
           [0003]    2. Description of the Related Art  
           [0004]    Recording media, e.g., a micro-magnetic disk cartridge called “clik!” (registered trademark) shown in a schematic perspective view in FIG. 9, have conventionally been used for mobile equipment such as digital cameras.  
           [0005]    [0005]FIGS. 10A to C are a plan view, a right side view, and a bottom plan view of a closed rotary shutter  7  of a magnetic disk cartridge  1 , respectively. FIGS. 11A and B are a plan view and a bottom plan view of the opened rotary shutter  7 , respectively. FIG. 12 is an exploded perspective view of the magnetic disk cartridge  1 . As shown in these drawings, a flat housing of the magnetic disk cartridge  1  rotatably contains a magnetic disk  5 . A resin frame  2  and upper and lower shells  3  and  4  constitute the housing. The resin frame  2  includes a pressing portion  2   a , and the upper and lower shells  3  and  4  are made of thin metal plates. The dimensions of the housing are 50 mm wide by 55 mm deep by 1.95 mm thick. The magnetic disk  5  has a storage capacity of 40 MB and a diameter of 1.8 inches (45.7 mm).  
           [0006]    The magnetic disk cartridge  1  is provided with a V-shaped opening  6  and a rotary shutter  7 . The opening  6  is for a magnetic head provided in a disk drive, into which the cartridge  1  is inserted to be mounted, to access the surface of the magnetic disk  5 , and the rotary shutter  7  opens and closes the opening  6 . Upper and lower shutter members  7 U and  7 D (refer to FIG. 12) engage each other to form the rotary shutter  7 , and a center pin  17  axially supports the upper shutter member  7 U beneath the upper shell  3 . Liners  18  are individually inserted between the magnetic disk  5  and the upper shutter member  7 U and between the magnetic disk  5  and the lower shutter member  7 D.  
           [0007]    In addition, a notch  8  is formed in the top portion on the left side of the housing in FIG. 10A, and a small window  9  is formed in the top portion of the right side. The notch  8  engages with an engaging member of the disk drive to ensure the positioning of the magnetic disk cartridge  1  in the disk drive. The small window  9  is for a shutter locking member  11 , which locks the rotary shutter  7  at a closed position, to face the exterior.  
           [0008]    A circular opening  4   a  and an arcuate groove  4   b  are formed on the lower shell  4  of the housing. The opening  4   a  is for a center core  10  of the magnetic disk  5  to connect with a drive spindle of the disk drive, and the arcuate groove  4   b  is concentric with the rotary shutter  7 . A shutter knob  7   b  is fixed to the lower shutter  7   d . The shutter knob  7   b  protrudes from the arcuate groove  4   b  and moves along the arcuate groove  4   b  to open and close the rotary shutter  7 .  
           [0009]    [0009]FIGS. 13A and B are plan views of the rotary shutter  7  in its closed and opened state, respectively, shown by removing the upper shell  3  and omitting the magnetic disk  5 .  
           [0010]    The shutter locking member  11  is provided with an engaging protrusion  11   a  at the tip thereof. The protrusion  11   a  can engage with an engaging recess  7   c  formed on the periphery of the rotary shutter  7 , and the shutter locking member  11  locks the rotary shutter  7  at the closed position. The shutter locking member  11  is rotatably attached to a shaft  12  provided in the housing, and a spring plate  11   b  urges the shutter locking member  11  in the direction (counterclockwise direction in FIG. 13) that enables the engaging protrusion  11   a  to engage with the engaging recess  7   c . When the magnetic disk cartridge  1  is inserted into the disk drive, a lock releasing member provided in the disk drive passes through the small window  9  to press the shutter locking member  11 . Accordingly, the locking member  11  is slightly rotated clockwise, and the engaging protrusion  11   a  escapes from the engaging recess  7   c . Thus, the lock on the rotary shutter  7  is released.  
           [0011]    A long thin coil spring  14  with a small diameter urges the rotary shutter  7  in a closing direction (counterclockwise direction in FIG. 13). A guide wire  13  is provided to mount the coil spring  14  thereto. One end of the guide wire  13  is latched to the frame  2  at a portion  2   b  which faces the periphery of the rotary shutter  7 , and the other end slidably penetrates a support member  7   d  fixed to the periphery of the rotary shutter and extends along the periphery of the rotary shutter  7 . As shown in FIG. 13A, the coil spring  14  is compressed and provided between the portion  2   b  of the frame  2  and the support member  7   d  so as to be compressed and expanded along the guide wire  13 . The coil spring  14  urges the rotary shutter  7  in the closing direction (counterclockwise direction in FIG. 13). When the rotary shutter  7  which has been released from the lock is rotated from this state in a clockwise direction in FIG. 13, the coil spring  14  becomes compressed as shown in FIG. 13B.  
           [0012]    Incidentally, when assembling the foregoing conventional magnetic disk cartridge  1 , the upper and lower shells  3  and  4  cover the frame  2  from the top and bottom thereof, and edges of the upper and lower shells  3  and  4  abut each other. Thereafter, as shown in FIG. 9, ten or more spots P are laser welded to assemble the disk cartridge  1 . Hence, it takes considerable time and energy to disassemble the disk cartridge  1  for recycling and waste separation and disposal since the welds must be broken.  
         SUMMARY OF THE INVENTION  
         [0013]    In consideration of the foregoing circumstances, an object of the present invention is to provide this type of disk cartridge, which is capable of being disassembled without breaking welds.  
           [0014]    The disk cartridge rotatably houses a disk, which is a recording medium, in a flat housing. The flat housing is constituted of a frame and upper and lower shells made of metal plates covering the top and bottom of the frame.  
           [0015]    The present invention is characterized in that an engaging protrusion is provided on at least one of upper and lower surfaces of the frame and an engaging aperture which engages with the engaging protrusion is formed on at least one of the upper and lower shells. The engaging protrusion can freely oscillate in and out from the surface and is elastically urged in the direction that the engaging protrusion protrudes from the surface.  
           [0016]    The present invention is also characterized in that the frame, in which the engaging protrusion is sunk from the surface, is inserted into a space formed between the upper and lower shells until the engaging protrusion is at a position to be aligned with the engaging aperture. Thus, the engaging protrusion engages with the engaging aperture, and the housing is assembled.  
           [0017]    The engaging protrusion is preferably coupled to the frame via thin portions which have elasticity and are integrally formed with the engaging protrusion and the frame by synthetic resin. In this case, a material of the frame is preferably ABS resin which is excellent in elastic deformability or polyester elastomer resin such as Hytrel (registered trademark).  
           [0018]    Alternatively, the engaging protrusion can be formed separately from the frame and coupled to the frame via thin portions which have elasticity and are integrally formed with the engaging protrusion.  
           [0019]    According to the disk cartridge of the present invention, a space is formed between the upper and lower shells by engagement of the upper and lower shells through, for example, welding. The frame, in which the engaging protrusion is sunk from the surface by thrust pressure against the urging force, is inserted into the space until the position the engaging protrusion is aligned with the engaging aperture. Accordingly, the engaging protrusion engages with the engaging aperture by the urging force, thereby assembling the housing. Thus, upon disassembly, the engagement between the frame and the upper and lower shells can be released by simply pressing the engaging protrusion engaged with the engaging aperture against the urging force. Therefore, there is an advantage that the disk cartridge can be easily disassembled without breaking the welds.  
           [0020]    Moreover, in the case where the engaging protrusion is coupled to the frame through the thin portions which have flexibility and are integrally formed with the engaging protrusion and the frame by synthetic resin, the engaging protrusion can obtain the urging force by the thin portions. Therefore, the structure of the disk cartridge becomes simple, facilitating the manufacture thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a perspective view schematically showing a housing in an embodiment of a magnetic disk cartridge according to the present invention.  
         [0022]    [0022]FIG. 2 is an exploded perspective view of the housing shown in FIG. 1.  
         [0023]    [0023]FIG. 3A is an enlarged sectional view showing the essential part of a frame shown in FIG. 2, and FIGS. 3B and C are enlarged plan views showing the essential part of the frame shown in FIG. 2.  
         [0024]    [0024]FIG. 4 is a perspective view showing a method of assembling the housing shown in FIG. 1.  
         [0025]    [0025]FIG. 5 is an enlarged sectional view of the essential part of the housing.  
         [0026]    [0026]FIGS. 6A to C are a plan view, a front view, and a plan view showing three modifications of the frame structures, respectively.  
         [0027]    [0027]FIG. 7 is an exploded perspective view of a housing in another embodiment of a magnetic disk cartridge according to the present invention.  
         [0028]    [0028]FIG. 8A is a sectional view showing a frame and an engaging member separate from the frame, and FIGS. 8B and C are a perspective view and a plan view showing the engaging member, respectively.  
         [0029]    [0029]FIG. 9 is a perspective view showing a conventional magnetic disk cartridge.  
         [0030]    [0030]FIGS. 10A to C are a plan view, a right side view and a bottom plan view showing the magnetic disk cartridge in FIG. 9 when a rotary shutter is closed, respectively.  
         [0031]    [0031]FIGS. 11A and B are a plan view and a bottom plan view showing the magnetic disk cartridge in FIG. 9 when the rotary shutter is open, respectively.  
         [0032]    [0032]FIG. 12 is an exploded perspective view showing the magnetic disk cartridge in FIG. 9.  
         [0033]    [0033]FIGS. 13A and B are plan views showing a positional relationship between inner parts when the rotary shutter of the magnetic disk cartridge in FIG. 9 is closed and opened, respectively. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    Embodiments of the present invention are detailed below with reference to the drawings.  
         [0035]    FIGS.  1  to  5  are views schematically showing a housing of a magnetic disk cartridge according to the present invention. FIG. 1 is a perspective view of the assembled magnetic disk cartridge, and FIG. 2 is an exploded perspective view of the magnetic disk cartridge. To facilitate understanding, the constituent parts are shown with dimensions having ratios different from the actual ratios, and details are omitted in FIGS.  1  to  5  to schematically show the magnetic disk cartridge.  
         [0036]    In FIGS. 1 and 2, a synthetic resin frame  22  and upper and lower shells  23  and  24  constitute the housing of the magnetic disk cartridge  20 . The frame  22  is preferably made of ABS resin or polyester elastomer resin such as Hytrel (registered trademark) and the like, and the upper and lower shells  23  and  24  are made of 0.2 mm-thick stainless steel plates. Of the magnetic disk cartridge  20 , only the structure of the housing differs from the conventional magnetic disk cartridge  1  shown in FIGS. 9 through 13. In other respects, the magnetic disk cartridge  20  has substantially the same parts contained in the housing as the conventional magnetic disk cartridge  1 .  
         [0037]    The upper shell  23  is formed of a flat part  23   a  and sidewalls  23   b  extending perpendicularly from the periphery of the flat part  23   a , excluding a straight front edge  23   d . Engaging apertures  23   c  and  23   c  are provided in the vicinity of the right and left ends of the front edge  23   d . Engaging protrusions  25  of the frame  22 , to be described later, engage with the engaging apertures  23   c  and  23   c . The lower shell  24  is formed of a flat part  24   a  and sidewalls  24   b . The flat part  24   a  has the same outer shape as that of the flat part  23   a  of the upper shell  23 , and the sidewalls  24   b  extend upward from the outer edge of the flat part  24   a , excluding a straight front edge  24   d . At the center of the flat part  24   a , a circular aperture  24   c  is formed for a center core  10  to face the exterior.  
         [0038]    The frame  22  comprises an arcuate inner edge  22   a  as well as engaging protrusions  25  at the right-and-left ends of the upper surface. As shown in an enlarged sectional view in FIG. 3A and an enlarged plan view in FIG. 3B, the engaging protrusion  25  is supported by four thin portions  27  to protrude from an upper surface  22   b  of the frame  22 . The four thin portions  27  extend from an inner wall of an aperture  26  toward the center of the aperture  26  as beams, and the aperture  26  penetrates the frame  22  from the top to the bottom. The engaging protrusions  25  and the thin portions  27  are integrally formed with the frame  22  by a synthetic resin material. The four thin portions  27  have elasticity. Thus, by depressing the upper surface of the engaging protrusion  25 , the engaging portion  25  can be sunk from the upper surface  22   b  of the frame  22  as indicated by broken lines in FIG. 3A. This urges the engaging protrusion  25  in a direction so that the engaging protrusion protrudes from the upper surface  22   b  of the frame  22 , in other words, in an upward direction. Note that the number of the thin portions  27  may be three, and the number of the beam-like thin portions is not particularly limited. Alternatively, the thin portion  27  may enclose the entire periphery of the engaging protrusion  25  as a diaphragm as shown in FIG. 3C.  
         [0039]    To assemble a housing by use of the frame  22  and the upper and lower shells  23  and  24  having these structures, first, side edges  23   b  and  24   b  of the upper and lower shells  23  and  24  are abutted and integrated by, for example, welding, to form a space having an opening  30  defined by straight front edges  23   d  and  24   d , as shown in FIG. 4.  
         [0040]    Next, the engaging protrusions  25  and  25  are depressed and sunk from the upper surface  22   b  of the frame  22  into the apertures  26  and  26 , and the frame  22  is inserted into the space between the upper and lower shells  23  and  24  from the opening  30 . At this time, the engaging protrusions  25  and  25  are abutted on the lower surface of the upper shell  23  and slide along the lower surface of the flat part  23   a  of the upper shell  23 . When the frame  22  is inserted to the position at which the engaging protrusions  25  and  25  are aligned with the engaging apertures  23   c  and  23   c  of the upper shell  23 , the thin portions  27  elastically urge the engaging protrusions  25  and  25  upward to engage with the engaging apertures  23   c  and  23   c , respectively, as shown in FIG. 5. Accordingly, the frame  22  engages between the upper and lower shells  23  and  24 . Thus, the assembly of the housing is completed. Note that it is not preferable for the engaging protrusion  25  to protrude from the surface of the upper shell  23  in the assembly shown in FIG. 5.  
         [0041]    As apparent from the description, according to the present embodiment, the upper and lower shells  23  and  24  are integrated by, for example, welding, and a space is formed between the upper and lower shells  23  and  24 . The frame  22 , in which the engaging protrusions  25  and  25  are pressed and sunk from the upper surface, is inserted into the space to the position at which the engaging protrusions  25  and  25  elastically engage with the engaging apertures  23   c  and  23   c . Accordingly, the housing is assembled. Thus, upon disassembly of the housing, the frame  22  can be pulled out from the space between the upper and lower shells  23  and  24  by simply pressing the engaging protrusions  25  and  25  engaged with the engaging apertures  23   c  and  23   c  to release the engagements between the engaging protrusions  25  and  25  and engaging apertures  23   c  and  23   c . Therefore, a disk cartridge of the present invention has an advantage that the disk cartridge can be easily disassembled without breaking the welds.  
         [0042]    Moreover, the engaging protrusions  25  and  25  are coupled to the frame  22  through the thin portions  27 , which have elasticity and are integrally formed with the engaging protrusions  25  and  25  and the frame  22 . Thus, the structure of the disk cartridge is simple and can be easily produced.  
         [0043]    Upon disassembly, the engaging protrusions  25  and  25  may be depressed with strong force to break the thin portions  27 . However, to recycle the parts, it is preferable to deform the thin portions  27  temporarily, instead of breaking them.  
         [0044]    In the embodiment described above, two cylindrical engaging protrusions  25  and  25  are provided on the upper surface of the frame  22 . However, as shown in FIG. 6A, three or more protrusions  25  may be provided. Moreover, as shown in FIG. 6B, the protrusions  25  can be provided on both upper and lower surfaces of the frame  22 . In this case, the engaging apertures are provided on the flat part  24   a  of the lower shell  24  as well, at the positions corresponding to the engaging protrusions  25 . Furthermore, the shape of the engaging protrusion is not limited to a cylinder. As shown in FIG. 6C, an engaging protrusion  25 ′ with an elongate shape when viewed from above maybe employed.  
         [0045]    In addition, as shown in FIG. 7, the engaging protrusions  25  can be provided on both sides of the frame  22 . In this case, the apertures  26  are provided horizontally in the frame  22 , and engaging apertures  29  are provided on both sides of the upper and lower shells  23  and  24 .  
         [0046]    Furthermore, as shown in FIGS. 8A and B, an engaging member  32 , separate from the frame  22 , having an engaging protrusion  35  and a circular elastic thin portion  37  can be employed. In this case, a circular recess  36  is provided on the frame  22  to receive this engaging member  32 , and grooves  36   a  are provided in the periphery of the bottom of the recess  36  to engage with the outer edge of the thin portion  37  to hold the engaging member  32 . Although the engaging member  32  shown in perspective and plan views in FIG. 8B comprises a circular elastic thin portion  37 , the engaging member  33  comprising quadrilateral thin portions  38  extending in four directions can be employed as shown in perspective and plan views in FIG. 8C.  
         [0047]    Since the thin portion  37  of the engaging member  32  and the thin portions  38  of the engaging member  33  are required to be elastic, the engaging members  32  and  33  are preferably made by a wringing process from a PET sheet material or a PC (polycarbonate) sheet material when formed of resin. In the case that metal is employed as the material, the engaging members  32  are  33  are preferably made by wringing process from stainless steel plates.