Abstract:
A disk cartridge comprising a flat housing and a recording disk medium. The flat housing is constructed of upper and lower metal shells, and the recording disk medium is rotatably enclosed within the housing. The housing is assembled by mechanically linking the circumferential edge portions of the upper and lower shells together.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a disk cartridge in which a recording disk medium is rotatably enclosed within a housing made up of upper and lower metal shells, and more particularly to the assembled structure of the housing. 
     2. Description of the Related Art 
     In mobile equipment such as digital cameras, etc., a very small disk cartridge, called “clik!™” such as that described in U.S. Pat. No. 6,256,168, is in use as a recording medium. This disk cartridge 1 is 50 mm in width, 55 mm in depth, and 1.95 mm in thickness, as schematically shown in  FIG. 12 . It has a housing, which is constructed of a resin frame  2 , and upper and lower metal shells  3 ,  4  formed from a stainless steel sheet of 0.2 mm in thickness. Within the housing, there is rotatably enclosed a magnetic disk of diameter 1.8 inch (about 45.7 mm) which has a recording capacity of 40 MB. The housing is equipped with a U-shaped opening  6  through which a magnetic head is positioned over a recording surface of the magnetic disk, and a rotary shutter  7  that covers the U-shaped opening  6  when read and write operations are not performed. As illustrated in  FIG. 12 , the upper and lower shells  3 ,  4  are laser welded at 10 or more positions P with the upper and lower circumferential wall portions abutting each other. 
     The assembled structure of the housing in the above-described conventional disk cartridge, however, has the following problems: (1) an expensive, special machine such as a laser welding machine is required and the upper and lower shells need to be precisely positioned so they are not shifted from each other; (2) paper or sputter dust particles occur at the time of welding, adhere to a recording medium, and have an adverse influence on read and write operations, and also contaminate assembly space (which requires a class 100 to 1000 clean room); (3) in the case of welding the circumferential edges of upper and lower shells, at welded portions the circumferential edge of one shell is provided with tabs protruding slightly from the other shell, and consequently, at portions other than the welded portions there occur slight gaps between both circumferential edges and the problem of the occurrence of dust particles will arise; and (4) when disassembling the welded upper and lower shells for recycling or collection of classified refuse, the welded portions have to be destroyed and therefore the operation of disassembling them is time-consuming. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the circumstances described above. Accordingly, it is the object of the present invention to provide an assembled structure of upper and lower shells that solves all the problems mentioned above. 
     To achieve this end and in accordance with the present invention, there is provided a disk cartridge comprising a flat housing and a recording disk medium. The flat housing is constructed of upper and lower metal shells, and the recording disk medium is rotatably enclosed within the housing. The housing is assembled by mechanically linking the circumferential edge portions of the upper and lower shells together. 
     In a preferred form of the present invention, the circumferential edge portions of the upper and lower shells are joined mechanically by engagement between grooves and protrusions formed in the upper and lower shells. 
     In another preferred form of the present invention, the circumferential edge portions of the upper and lower shells are joined mechanically by caulking either the circumferential wall portion of the upper shell or the circumferential wall portion of the lower shell. 
     In still another preferred form of the present invention, the upper and lower shells are formed by folding back a single metal plate. 
     In a further preferred form of the present invention, one of the circumferential edge portions of the upper and lower shells has fastening tongues, while the other circumferential edge portion has recesses at positions corresponding to the fastening tongues. And the circumferential edge portions of the upper and lower shells are joined mechanically by bending the fastening tongues inserted in the recesses. 
     In a further preferred form of the present invention, one of the circumferential edge portions of the upper and lower shells has windows, while the other circumferential edge portion has locking pieces at positions corresponding to the windows. And the circumferential edge portions of the upper and lower shells are joined mechanically by elastically fitting the locking pieces in the windows. 
     Further, the circumferential edge portions of the upper and lower shells can be joined mechanically by combining some of the aforementioned fastening tongues, recesses, locking pieces, and windows, or by using an adhesion or hot melting method at the same time. 
     According to the present invention, the upper and lower metal shells of the disk cartridge housing are joined mechanically by caulking or the like, without welding. Therefore, an expensive specialized machine such as a laser welding machine is not required and the disk cartridge housing can be easily and precisely assembled. In addition, there is no possibility that paper or sputter dust particles, which can contaminate the assembly environment and have an adverse influence on read and write operations, will be generated during assembly. Furthermore, when disassembling the upper and lower shells for recycling or collection of classified refuse, the disassembly operation is easy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in further detail with reference to the accompanying drawings wherein: 
         FIG. 1A  is a schematic sectional view, partly omitted, showing the upper shell of a disk cartridge housing constructed in accordance with a first embodiment of the present invention; 
         FIG. 1B  is a schematic sectional view, partly omitted, showing the lower shell of the disk cartridge housing constructed in accordance with the first embodiment of the present invention; 
         FIG. 1C  is a schematic sectional view, partly omitted, showing the upper and lower shells joined together; 
         FIG. 2A  is a sectional view showing a disk cartridge constructed in accordance with a second embodiment of the present invention; 
         FIG. 2B  is a sectional view showing the state in which an upper shell is placed on the step portion of a lower shell; 
         FIG. 2C  is a sectional view showing the state in which the upper and lower shells are assembled into a housing by caulking; 
         FIGS. 3A to 3C  are enlarged sectional views showing different caulking portions by means of which upper and lower shells are mechanically joined; 
         FIG. 4  is a sectional view showing a disk cartridge constructed in accordance with a third embodiment of the present invention; 
         FIG. 5  is an exploded perspective view of a disk cartridge housing constructed in accordance with a fourth embodiment of the present invention; 
         FIG. 6  is an enlarged sectional view showing the principal part of the disk cartridge housing of the fourth embodiment; 
         FIG. 7A  is a front view showing the principal part of the upper shell of a disk cartridge housing constructed in accordance with a fifth embodiment of the present invention; 
         FIG. 7B  is a sectional view showing the principal part of the upper shell of the disk cartridge housing constructed in accordance with the fifth embodiment; 
         FIG. 8A  is a front view showing the principal part of a lower shell that is joined to the upper shell of  FIG. 7 ; 
         FIG. 8B  is a sectional view of the principal part of the lower shell shown in  FIG. 8A ; 
         FIG. 9A  is a front view showing the state in which the upper and lower shells of  FIGS. 7 and 8  are mechanically joined; 
         FIG. 9B  is a sectional view showing the state in which the upper and lower shells of  FIGS. 7 and 8  are mechanically joined; 
         FIG. 10  is a sectional view showing an alteration of the joined structure of  FIG. 9B ; 
         FIG. 11  is a plan view showing the joined portions of the upper and lower shells of a disk cartridge constructed in accordance with the fifth embodiment of the present invention; and 
         FIG. 12  is a perspective view showing a conventional disk cartridge. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will hereinafter be described in detail with reference to the drawings. To facilitate understanding of the present invention, the dimensions of each part will be shown at ratios differing from those of the actual dimensions. 
     Referring now to  FIGS. 1A to 1C , there is shown a disk cartridge housing  5  constructed in accordance with a first embodiment of the present invention. 
     An upper shell  3  illustrated in  FIG. 1A  consists of a flat plate portion  3   a  constituting the ceiling plate of the housing  5 , and a circumferential wall portion  3   b  extending downwardly from the circumferential edge of the flat plate portion  3   a . The interior wall surface of the circumferential wall portion  3   b  has a groove  11  extending parallel to the flat plate portion  3   a.    
     A lower shell  4  illustrated in  FIG. 1   b  consists of a flat plate portion  4   a  constituting the bottom plate of the housing  5 , and a circumferential wall portion  4   b  extending upwardly from the circumferential edge of the flat plate portion  4   a . The circumferential wall portion  4   b  is inserted inside the circumferential wall portion  3   b  of the upper shell  3 , and the exterior wall surface has a ridge  12  engageable with the groove  11  and extending parallel to the flat plate portion  4   a.    
     The above-described upper shell  3  and lower shell  4 , as illustrated in  FIG. 1C , are joined mechanically by the projection/groove engagement between the groove  11  and ridge  12 , and constitute the housing  5 . Preferably, the height of the ridge  12  from the exterior wall surface of the circumferential wall portion  4   b  is about 50% of the thickness of the circumferential wall portion  4   b.    
     Referring to  FIGS. 2A to 2C , there is shown a disk cartridge constructed in accordance with a second embodiment of the present invention. This embodiment is characterized in that a housing  5  is assembled by caulking upper and lower shells  3 ,  4 . 
     As illustrated in  FIG. 2A , the upper shell  3  consists only of a flat metal plate  3   a  and has a discoid liner  16  adhesively attached on the under side of the flat metal plate  3   a . The lower shell  4  is equipped with a circumferential wall portion  4   b  rising upwardly from the circumferential edge of a flat plate portion  4   a . The upper portion of the circumferential wall portion  4   a  serves as a caulking portion  14 , and the proximal portion of the caulking portion  14  has a step portion  14   a  that receives the circumferential edge of the upper shell  3  to regulate the spacing between the upper and lower shells  3 ,  4 . Also, the flat plate portion  4   a  of the lower shell  4  has a drive spindle aperture  4   c  so a drive spindle (not shown) of a disk drive unit (not shown) can spin a magnetic disk  15  through a center core  10  mounted on the magnetic disk  15 . The lower shell  4  further has a doughnut-shaped liner  16  adhesively attached on the upper side thereof, and the above-described magnetic disk  15  is placed on the doughnut-shaped liner  16 . 
     As illustrated in  FIG. 2B , the upper shell  3  is placed on the step portion  14   a  of the lower shell  4 . And as illustrated in  FIG. 2C , the caulking portion  14  is caulked to the circumferential edge portion of the upper plate portion  3   a  of the upper shell  3  by bending the caulking portion  14  inwardly, whereby the housing  5  is assembled. 
       FIGS. 3A to 3C  show different caulking portions by means of which upper and lower shells  3 ,  4  are mechanically joined.  FIG. 3A  shows an enlarged sectional view of the principal part of  FIG. 2C . 
     In the case of  FIG. 3B , the lower end of the circumferential wall portion  3   b  of the upper shell  3  abuts the upper side of the flat plate portion  4   a  of the lower shell  4  to regulate the spacing between the upper and lower shells  3 ,  4 . The circumferential wall portion  4   b  of the lower shell  4  extends upwardly along the exterior wall of the circumferential wall portion  3   b  of the upper shell  3  and forms double walls, and the upper end portion of the circumferential wall portion  4   b  of the lower shell  4  is bent inwardly and caulked to the circumferential edge portion of the upper plate portion  3   a  of the upper shell  3 , whereby the housing is assembled. 
     In the case of  FIG. 3C , the lower portion of the circumferential wall portion  3   b  of the upper shell  3  is folded back outwardly and forms a folded-back portion  19 . The circumferential wall portion  4   b  of the lower shell  4  has a step portion  4   d , which receives the lower end of the folded-back portion  19  to regulate the spacing between the upper and lower shells  3 ,  4 . And the upper end portion of the circumferential wall portion  4   b  of the lower shell  4  is bend inwardly as a caulking portion  20  and caulked onto the folded-back portion  19  of the upper shell  3 , whereby the housing is assembled. 
     Referring to  FIG. 4 , there is shown a disk cartridge constructed in accordance with a third embodiment of the present invention. This embodiment is characterized in that upper and lower shells  3 ,  4  are formed by folding and caulking a single metal plate  21 . That is, at approximately the longitudinal center position of the metal plate  21 , a protrusion  21   a  is formed so it extends perpendicular to the longitudinal direction of the metal plate  21 , and by folding back the metal plate  21  along the protrusion  21   a , the left-side plate portion  21   b  of the protrusion  21   a  forms the flat plate portion of the upper shell  3 , while the right-side plate portion  21   d  of the protrusion  21   a  forms the flat plate portion of the lower shell  4 . Also, the circumferential edge portion  21   c  of the left-side plate portion  21   b  is bent and formed into the circumferential wall portion of the upper shell  3 . Similarly, the circumferential edge portion  21   e  of the right-side plate portion  21   d  is bent and formed into the circumferential wall portion of the lower shell  4 . For example, the circumferential edge portions  21   c ,  21   e  are joined by bending a caulking portion  17  inwardly, as illustrated in  FIG. 3B . 
     Referring to  FIG. 5 , there is shown a disk cartridge constructed in accordance with a fourth embodiment of the present invention. In this embodiment, the lower edge of the circumferential wall portion  3   b  of an upper shell  3  is provided with a plurality of fastening tongues  22 , and the circumferential edge portion of the flat plate portion  4   a  of a lower shell  4  has a plurality of recesses  23  at the positions corresponding to the fastening tongues  22 . After the fastening tongues  22  on the side of the upper shell  3  are inserted through the recesses  23  of the lower shell  4 , the fastening tongues  22  projected downwardly from the under side of the flat plate portion of the lower shell  4  are bent inwardly as shown in  FIG. 6 , whereby the housing is assembled. Note that the fastening tongues  22  may be provided on the side of the lower shell  4  and the recesses  23  on the side of the upper shell  3 . 
     Referring to  FIGS. 7 to 9 , there is shown a disk cartridge constructed in accordance with a fifth embodiment of the present invention.  FIGS. 7A and 7B  show front and sectional views of the principal part of the circumferential wall portion of the upper shell of the fifth embodiment,  FIGS. 8A and 8B  show front and sectional views of the principal part of the circumferential wall portion of the lower shell of the fifth embodiment, and  FIGS. 9A and 9B  show front and sectional views of the state in which the upper and lower shells are mechanically joined. 
     In  FIGS. 7A and 7B , the flat plate portion  30   a  of the upper shell  30  of the fifth embodiment is formed from a SUS 304 steel sheet of thickness 0.2 mm, and the circumferential wall portion  30   b  of the upper shell  30  is formed by bending the circumferential edge portion of the flat plate portion  30   a  downwardly at a right angle. The circumferential wall portion  30   b  has a plurality of rectangular windows  31 . In the fifth embodiment, the height of the circumferential wall portion  30   b  is 1.95 mm, and the longitudinal length of the window  31  is slightly longer than 2 mm and the transverse length is 0.9 mm. The lower edge of the window  31  extends parallel to the lower edge of the wall portion  30   b  at a position 0.5 mm away from the lower edge of the wall portion  30   b.    
     In  FIGS. 8A and 8B , the flat plate portion  40   a  of the lower shell  40  of the fifth embodiment is likewise formed from a SUS  304  steel sheet of thickness 0.2 mm, and the circumferential wall portion  40   b  of the lower shell  40  is formed by bending the circumferential edge portion of the flat plate portion  40   a  upwardly at a right angle, and is arranged inside the circumferential wall portion  30   b  of the upper shell  30 . At the positions corresponding to the windows  31 , there are provided locking pieces  41 , which are rectangular in shape and 2.0 mm in width. The number of locking pieces  41  corresponds to the number of windows  31 . Each of the locking pieces  41  has a lower edge and side edges cut away from the circumferential wall portion  40   b  of the lower shell  40 , and the lower edge is projected outwardly from the circumferential wall portion  40   b.    
     When the circumferential wall portion  40   b  of the lower shell  40  is inserted inside the circumferential wall portion  30   b  of the upper shell  30 , the locking pieces  41  of the lower shell  40  are elastically bent inwardly by the lower edge portion of the circumferential wall portion  30   b  of the upper shell  30 , and as soon as the top surface of the circumferential wall portion  40   b  of the lower shell  40  abuts the under side of the flat plate portion  30   a  of the upper shell  30 , the locking pieces  41  restore to their original states and are fitted in the windows  31 . As illustrated in  FIGS. 9A and 9B , the upper and lower shells  30 ,  40  are mechanically joined at the circumferential wall portions  30   b ,  40   b.    
     In the joined structure described above, even if force is applied so the upper and lower shells  30 ,  40  are further pushed, the top end of the circumferential wall portion  40   b  of the lower shell  40  abuts the under side of the flat plate portion  30   a  of the upper shell  30  at position A indicated in  FIG. 9B , and consequently, it is impossible to push them any further. Also, even if force is applied so the upper and lower shells  30 ,  40  are vertically separated from each other, the lower edge of each of the fastening pieces  41  of the lower shell  40  abuts the lower edge of the corresponding window  31  of the upper shell  30  at position B indicated in  FIG. 9B , so it is impossible to separate them. 
     Further, even when force is applied so that the circumferential wall portions  30   b ,  40   b  of the upper and lower shells  30 ,  40  are shifted horizontally from each other, the side edge of the locking piece  41  abuts the side edge of the window at position C or D indicated in  FIG. 9A , so it is also impossible to shift the upper and lower shells  30 ,  40  horizontally. 
     However, if the locking pieces  41  are disengaged from the windows  31  by being bent inwardly, the upper and lower shells  30 ,  40  can be vertically separated. 
     Thus, although the joined structure of the upper and lower shells  30 ,  40  in the fifth embodiment is simple, the housing is extremely easy to assemble, and although the joined strength of the upper and lower shells  30 ,  40  is high, it is also possible to disassemble them. 
     Instead of the above-described structure, the circumferential wall portion  40   b  of the lower shell  40  may be provided with windows  42  and the circumferential wall portion  30   b  of the upper shell  30  may have locking pieces  32 , as shown in  FIG. 10 . Similarly, the above-described advantages can be obtained. 
       FIG. 11  illustrates a plan view of the case where the joined structure of the upper and lower shells in  FIGS. 9A and 9B  is employed in the magnetic disk cartridge  1  described in  FIG. 12 , and the upper and lower shells are joined at  13  positions indicated by arrows S. Note in  FIG. 11  that reference numeral  15  denotes a magnetic disk. 
     As evident in the foregoing description, the above-described embodiments are excellent in assembly characteristics and disassembly characteristics, do not contaminate the assembly environment, and have no adverse influence on read and write operations. 
     While the present invention has been described with reference to the preferred embodiments thereof, the invention is not to be limited to the details given herein, but may be modified within the scope of the invention hereinafter claimed.