Abstract:
A disk cartridge including a recording disk medium of diameter 2 inches or less and a housing. The housing is made up of a frame and upper and lower metal shells. The frame has a plurality of recesses in the side walls thereof, and the side walls of the upper and lower shells are provided with a plurality of elastic engagement pieces respectively engageable with the recesses. The housing is assembled by engagement of the elastic engagement pieces with the recesses.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a small disk cartridge in which a recording disk medium of diameter 50.8 mm (about 2 inches) or less is rotatably enclosed within a housing made up of a frame and upper and lower metal shells covering the top surface and bottom surface of the frame, and more particularly to the structure of the housing assembled. 
     2. Description of the Related Art 
     In mobile equipment such as a digital camera, etc., a very small disk cartridge, called “clik!™” such as that schematically shown in  FIG. 9 , is being used as a recording medium. This disk cartridge  1  is 50 mm in width, 55 mm in depth, and 1.95 mm in thickness. It has a housing, which is made up of a resin frame  2  and upper and lower metal shells (stainless steel sheets of 0.2 mm in thickness)  3 ,  4 . The housing rotatably encloses a magnetic disk of diameter 1.8 inch (about 45.7 mm) which has a recording capacity of 40 MB, and is equipped with a U-shaped hole  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 hole  6  when read and write operations are not performed. The upper and lower shells  3 ,  4  are laser welded at 10 or more positions (P) with the circumferential edges of the side walls engaged with each other. 
     In a magnetic disk cartridge (not shown) with a 3.5-inch (89-mm) floppy disk which is in wide use as a recording medium for personal computers, the upper and lower resin shells of the housing are assembled by ultrasonic bonding. 
     The structure of the assembled housing in the conventional disk cartridges described above, however, has the following problems: (1) an expensive, special machine such as a laser welding machine and an ultrasonic bonding machine is required and the upper and lower shells need to be precisely positioned so they are vertically aligned with each other; (2) paper or sputter dust occurs at the time of welding or bonding, adheres to a recording medium, and has an adverse influence on read and write operations, and also contaminates assembly space (which requires a class 100 to 1000 clean room); and (3) when disassembling the welded or bonded upper and lower shells for recycling or collection of classified refuse, the disassembly of them is fairly difficult and time-consuming, and since they are destroyed by disassembly, it is impossible to recycle them. 
     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 a structure of upper and lower shells which has fixed all the problems found in the prior art. 
     To achieve this end and in accordance with the present invention, there is provided a disk cartridge comprising a recording disk medium of diameter 2 inches or less and a housing. The housing is made up of a frame and upper and lower metal shells covering the top surface and bottom surface of the frame, and within the housing, the disk medium is rotatably enclosed. The frame has a plurality of recesses in the side walls thereof, and the side walls of the upper and lower shells are provided with a plurality of elastic engagement pieces respectively engageable with the recesses of the frame. The housing is assembled by engagement of the elastic engagement pieces with the recesses. 
     In one preferred form of the present invention, the elastic engagement pieces are constructed to be engageable with the recesses of the frame along a vertical direction. In that case, the side walls of one of the upper and lower shells may be further provided with elastic engagement pieces that are engageable directly with the side walls of the other of the upper and lower shells. 
     In another preferred form of the present invention, the recesses in the side wall of the frame maybe a slot extending along a longitudinal direction of the side wall. In this case, the elastic engagement pieces are inserted in the slot from the tip end side of the slot and are engaged with the slot. 
     In still another preferred form of the present invention, the elastic engagement pieces slide on the side walls of the frame along longitudinal directions of the side walls and are engaged with the recesses. In that case, the upper and lower shells may be formed from a shape memory alloy. 
     According to the present invention, the side walls of the upper and lower metal shells are provided with a plurality of elastic engagement pieces respectively engageable with the recesses of the frame, and the cartridge housing is assembled by engagement of the elastic engagement pieces with the recesses. Therefore, an expensive, specialized machine such as a laser welding machine is not required and the cartridge housing can be easily and precisely assembled. In addition, there is no possibility that paper or sputter dust, which can contaminate assembly circumstance and have an adverse influence on read and write operations, will occur during assembly. Moreover, when disassembling the upper and lower shells for recycling or collection of classified refuse, the disassembly of them is easy and recycling of them is possible. Furthermore, if the upper and lower shells are formed from a shape memory alloy, and the elastic engagement pieces are configured to disengage from the above-described recesses at a predetermined temperature higher than the operating temperature, disassembly of the housing can be facilitated by heating the elastic engagement pieces when disassembling the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in further detail with reference to the accompanying drawings wherein: 
         FIG. 1  is an exploded perspective view showing a disk cartridge housing constructed in accordance with a first embodiment of the present invention; 
         FIGS. 2A-I  to  2 A-IV are front and sectional views showing how an elastic engagement piece formed on the side of an upper shell is engaged with a recess formed in a frame; 
         FIGS. 2B-I  to  2 B-IV are front and sectional views showing how an elastic engagement piece different from that of  FIG. 2A  is engaged with the recess; 
         FIGS. 2C-I  to  2 C-IV are front and sectional views showing how an elastic engagement piece different from that of  FIG. 2A  is engaged with the recess; 
         FIGS. 3A-I  to  3 A-IV are views similar to  FIGS. 2A-I  to  2 A-IV showing an alteration of the elastic engagement piece shown in  FIG. 2A ; 
         FIGS. 3B-I  to  3 B-IV are views similar to  FIGS. 2B-I  to  2 B-IV showing an alteration of the elastic engagement piece shown in  FIG. 2B ; 
         FIGS. 3C-I  to  3 C-IV are views similar to  FIGS. 2C-I  to  2 C-IV showing an alteration of the elastic engagement piece shown in  FIG. 2C ; 
         FIG. 4  is an exploded perspective view showing a disk cartridge housing constructed in accordance with a second embodiment of the present invention; 
         FIGS. 5A-I  and  5 A-II are sectional and front views showing how an elastic engagement piece of a lower shell is engaged directly with an engagement portion of an upper shell; 
         FIGS. 5B-I  and  5 B-II are sectional and front views showing how an elastic engagement piece differing from that of  FIG. 5A  is engaged directly with an engagement portion of an upper shell; 
         FIGS. 5C-I  and  5 C-II are sectional and front views showing how an elastic engagement piece differing from that of  FIG. 5A  is engaged directly with an engagement portion of an upper shell; 
         FIG. 6  is an exploded perspective view showing a disk cartridge housing constructed in accordance with a third embodiment of the present invention; 
         FIG. 7A  is a front view of the slot shown in  FIG. 6 ; 
         FIG. 7B  is a front view showing an alteration of the slot; 
         FIG. 7C  is a front view showing another alteration of the slot; 
         FIG. 8  is an exploded perspective view showing a disk cartridge housing constructed in accordance with a fourth embodiment of the present invention; and 
         FIG. 9  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. 
     Referring to  FIG. 1 , there is shown a disk cartridge housing constructed in accordance with a first embodiment of the present invention. The cartridge housing is made up of a resin frame  2  of approximately the same dimensions as the magnetic disk cartridge  1  shown in  FIG. 9 , and upper and lower metal shells  3 ,  4  arranged to cover the top surface and bottom surface of the frame  2 . From the viewpoint of availability and mechanical strength, it is desirable that the material of the upper and lower shells  3 ,  4  be a stainless steel sheet of thickness 0.15 to 0.2 mm, preferably 0.2 mm. 
     The frame  2  has arcuate arm portions inside which a disk (not shown) and a rotary shutter (not shown) are arranged. The outside walls of both arm portions are provided with a plurality of vertical recesses  11  extending between the top and bottom surfaces of the frame  2 . The side walls of the upper shell  3  are provided with a plurality of elastic engagement pieces  12  extending downward from the lower edge  3   a  of each side wall, and the upper engagement pieces  12  are engageable with the recesses  11  and formed integrally with the upper shell  3 . Similarly, the side walls of the lower shell  4  are provided with a plurality of elastic engagement pieces  12  extending upward from the upper edge  4   a  of each sidewall, and the lower engagement pieces  12  are engageable with the recesses  11  and formed integrally with the upper shell  4 . 
       FIGS. 2A to 2C  show three different elastic engagement pieces  12  formed on the side of the upper shell  3 , and recesses  11  on the side of the frame  2  which are respectively engaged by the elastic engagement pieces  12 .  FIGS. 2A-I ,  2 B-I, and  2 C-I show front views of the three different elastic engagement pieces  12 ,  FIGS. 2A-II ,  2 B-II, and  2 C-II show sectional views of the elastic engagement pieces  12 ,  FIGS. 2A-III ,  2 B-III, and  2 C-III show sectional views of the recesses  11  that are engaged by the elastic engagement pieces  12 , and  FIGS. 2A-IV ,  2 B-IV, and  2 C-IV show the state in which the elastic engagement piece  12  is engaged with the recess  11 , along with the lower shell  4 . 
     The elastic engagement piece  12 , shown in  FIGS. 1 and 2A , is equipped with a claw  12   a  that protrudes inwardly, and the recess  11  in the frame  2  has a corresponding step portion  11   a  that is engaged by the claw  12   a.  The elastic engagement piece  12  shown in  FIG. 2B  is equipped with a protrusion  12   b  that extends inwardly, and the recess  11  in the frame  2  has a corresponding dent  11   b  in which the protrusion  12   b  is fitted. The elastic engagement piece  12  shown in  FIG. 2C  is equipped with an aperture  12   c,  and the recess  11  of the frame  2  has a corresponding protrusion  11   c  that is fitted in the aperture  12   c.    
     As illustrated in  FIGS. 2A-IV ,  2 B-IV, and  2 C-IV, each elastic engagement piece  12  is inserted inside the lower shell  4  through the upper edge  4   a  of the lower shell  4 , and to facilitate the insertion, the proximal portion of each elastic engagement piece  12  has slits  3   b  on both sides, as shown in  FIGS. 2A-I ,  2 B-I, and  2 C-I. 
     Instead of the slits  3   b,  the proximal portion of each elastic engagement piece  12  may have a step portion  3   c,  as shown in  FIGS. 3A to 3C  corresponding to  FIGS. 2A to 2C . The step portion  3   c  is formed by bending the proximal portion of the elastic engagement piece  12  inside. This step portion  3   c  makes it easy to insert the elastic engagement piece  12  inside the lower shell  4  through the upper edge  4   a  of the lower shell  4 . 
     Likewise, the lower shell  4  is provided with a plurality of elastic engagement pieces  12 , which have the same construction as those of the upper shell  3 . In addition to the recesses  11  to be engaged by the upper engagement pieces  12  of the upper shell  3 , the frame  2  is further provided with recesses  11  that are engaged by the lower engagement pieces  12  of the lower shell  4 , as illustrated in  FIG. 1 . 
     Referring to  FIG. 4 , there is shown a disk cartridge housing constructed in accordance with a second embodiment of the present invention. This embodiment is an alteration of the first embodiment described above. That is, the arm portions of a frame  2  are shorter than those of the first embodiment, and the number of recesses  11  that are formed in the side walls of the arm portions is reduced. Because of this, some of the elastic engagement pieces in one of the upper and lower shells are engaged directly with the side walls of the other shell. 
       FIGS. 5A to 5C  show three different elastic engagement pieces  14  formed on the side of the lower shell  4 , and the engagement portions of the upper shell  3  which are respectively engaged by the elastic engagement pieces  14 .  FIGS. 5A-I ,  5 B-I, and  5 C-I show sectional views of the engagement portions of the three different elastic engagement pieces  14 .  FIGS. 5A-II ,  5 B-II, and  5 C-II show front views of the elastic engagement pieces  14 . 
     The elastic engagement piece  14 , shown in  FIGS. 4 and 5A , is equipped with a claw  14   a  that projects inwardly, and the upper shell  3  has a corresponding step portion  13   a  that is engaged by the claw  14   a.  The elastic engagement piece  14  shown in  FIG. 5B  is equipped with a protrusion  14   b  that extends inwardly, and the upper shell  3  has a corresponding dent  13   b  in which the protrusion  14   b  is fitted. The elastic engagement piece  14  shown in  FIG. 5C  is equipped with an aperture  14   c,  and the upper shell  3  has a corresponding protrusion  13   c  that is fitted in the aperture  14   c.    
     Referring to  FIG. 6 , there is shown a disk cartridge housing constructed in accordance with a third embodiment of the present invention. Note in the figure that an upper shell is omitted. 
     In the third embodiment, as illustrated in  FIG. 7A , the side wall of each arm portion of a frame  2  is provided with a slot  15 , which extends longitudinally from the tip end of the arm portion to the proximal portion. The lower edge  3   a  of an upper shell  3  (not shown) and the upper edge  4   a  of a lower shell  4  have elastic engagement pieces  16  bent inwardly at approximately a right angle. These elastic engagement pieces  16  are inserted in the slot  15  from the tip end side of the arm portion and are engaged with the slot  15 . In this case, two parallel slots  15  may be provided for the upper shell  3  and lower shell  4 , but from the viewpoint of miniaturization, one slot is preferred as shown in  FIG. 7A . In that case, the width t of the slot  15  needs to be set to a value such that the elastic engagement pieces  16  of the upper and lower shells  3 ,  4  can be inserted. 
     As illustrated in  FIG. 7B , the end portion of the slot  15  may be provided with an inclined portion  15   a  that narrows gradually. As the elastic engagement piece  16  is inserted in the slot  15 , it is engaged with the inclined portion  15   a.  As illustrated in  FIG. 7C , the slot  15  may be provided with a protrusion  15   b.  If an elastic engagement piece  16  with a hole (not shown) engageable with the protrusion  15   b  is inserted, it is engaged with the protrusion  15   b.    
     Referring to  FIG. 8 , there is depicted a disk cartridge housing constructed in accordance with a fourth embodiment of the present invention. In this embodiment, the side walls of a frame  2  have V-shaped notches  17 , and upper and lower shells  3 ,  4  are provided with elastic engagement pieces  18  and elastic portions  19 . The elastic engagement pieces  18  slide on both side walls of the frame  2  from the tip end side of each arm portion of the frame  2  and are fitted in the rear notches  17  formed in the proximal portions of the arm portions of the frame  2 . The elastic portions  19  are fitted in the front notches  17  formed in the tip end portions of the arm portions of the frame  2 . The engagement portion of each elastic engagement piece  18  may be formed as illustrated in  FIGS. 2 and 3 . 
     In the fourth embodiment, the upper and lower shells  3 ,  4  may be formed from a shape memory alloy such as a Co—Ni—Al system alloy. In that case, if the elastic engagement pieces  18  are constructed such that they are firmly fitted in the notches  17  at normal temperature and disengage from the notches  17  at a predetermined temperature higher than the operating temperature, for example, 80° C. or more, then disassembly of the housing can be facilitated by heating the elastic engagement pieces  18 . 
     It is apparent that the above-described embodiments are all excellent in assembly and disassembly, do not contaminate 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.