Abstract:
A disk cartridge includes a rotatable disk having upper and lower surfaces and an outer casing for rotatably housing the disk. The casing includes upper and lower shells which have a non-woven fabric polyester liner with round fibers having rough, irregular, diameters. The rough surface of the fibers makes the liner more compliant and thus less abrasive to the disk. The round fibers have irregular variation in diameter of 10% to 50% with variations of about 25% being preferable.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application of Ser. No. 09/021,501 filed Feb. 10,1998, now U.S. Pat. No. 6,148,495, which is a divisional of Ser. No. 06/613,880 filed Mar. 11, 1996 now U.S. Pat. No. 6,185,803, which is a continuation of 08/681,095 filed Jul. 22, 1996, now U.S. Pat. No. 5,677,818 issued Oct. 10, 1997 which is a continuation of Ser. No. 08/324,579 filed Oct. 18, 1994, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to disk cartridges for storing electronic information, and more particularly, to a disk cartridge having an improved fabric liner. 
     DESCRIPTION OF THE PRIOR ART 
     Removable disk cartridges for storing digital electronic information typically comprise an outer casing or shell that houses a magnetic, magneto-optical or optical disk upon which electronic information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. The disk is mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive engages with the disk hub in order to rotate the disk within the cartridge at a given speed. The outer shell of the cartridge typically has an aperture near one edge to provide access to the disk. A shutter or door mechanism is often provided to cover the aperture when the cartridge is not in use to prevent dust or other contaminants from entering the cartridge and settling on the recording surface of the disk. 
     Although the cartridge shell and shutter mechanism provide some protection against contaminants entering the cartridge, some contaminants will inevitably reach the recording surface of the disk. For example, dust, smoke and other debris may enter the cartridge through the disk hub or through the cartridge shutter when the disk is inserted in a disk drive. Additionally, magnetic particles may be generated during manufacturing of the disk cartridge as well as during read/write operations in the disk drive. These contaminants can interfere with a read/write head causing errors and a potential loss of information. 
     To reduce the risk of read/write errors resulting from particles on the disk surface, cartridge often include one or more fabric liners within the cartridge in contact with the disk surface. 
     U.S. Pat. No. 5,667,818, Ma et al., issued on an application from which a divisional application is the parent hereof. It describes a non-woven fabric liner which has been fuzzed to loosen fibers in a region which contacts the surface of the disk. The upstanding fibers wipe the surface of the disk while the main body of the liner remains spaced from the disk thereby reducing drag. A second non-woven fabric liner is attached to the inner surface of the other of the shells. 
     Making the liner more compliant and less abrasive to the disk and making the liner more abrasion resistant to protect itself, lead to improved performance of the disk cartridge system. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention an improved liner for a disk cartridge includes a polyester material having round fibers which vary in diameter along the length of the fibers. The rough surface of the polyester fiber makes the liner more compliant and less abrasive to the disk. Because of the variations in diameter along the length of the fiber, the liner is more abrasion resistant which protects the liner. This new liner provides greatly improved performance when compared with cartridges having liners made of prior material. 
     The foregoing and other objects, features, and advantages will be better understood from the following more detailed description and appended claims. 
    
    
     SHORT DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of a disk cartridge according a preferred embodiment of the present invention; 
     FIG. 2 is a sectional view of the cartridge of FIG. 1 taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a perspective view of a fabric liner affixed to the inner surface of the lower shell of the cartridge of FIG.  1  and illustrates a fuzzed region of the liner; 
     FIG. 4 is a perspective view of a fabric liner affixed to the inner surface of the upper shell of the cartridge of FIG. 1; 
     FIG. 5 is a close up view of a polyester fiber in accordance with the present invention; 
     FIG. 6 shows a liner in accordance with the invention; 
     FIG. 7 shows a prior art rayon fiber next to a prior art polyester fiber; 
     FIG. 8 shows a prior art polyester fiber; and 
     FIG. 9 shows a prior art rayon fiber. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings wherein like numerals indicate like elements throughout, there is shown in FIGS. 1-4 a prior art disk cartridge  10  comprising an outer casing  12  and a disk  14  having a hub  16  rotatably mounted in the casing  12 . The casing  12  comprises upper and lower shells (FIGS. 3 &amp; 4) that mate to form the casing. A shutter  18  is provided on the cartridge to cover an aperture (not shown) in the front edge  20  of the casing. When the cartridge is inserted into a disk drive (not shown), the shutter moves to the side exposing the aperture and thereby providing the read/write heads of the drive with access to the recording surface of the disk  14 . In the present embodiment, the disk  14  comprises a flexible or floppy magnetic disk, however, in other embodiments, the disk may comprise a rigid magnetic disk, a magneto-optical disk or an optical storage medium. The magnetic disk  14  is formed of a thin (e.g. 0.0025 inches), flexible, circular base of polymeric film. Each side of the flexible disk is coated with a layer of magnetic recording material to form upper and lower recording surfaces. 
     Referring to FIG. 2, in greater detail, the upper shell  22  of the outer casing  12  has an inner surface  22   a  disposed in facing relation to the upper side  14   a  of the rotatable disk  14 . Similarly, the lower shell  24  has an inner surface  24   a  disposed in facing relation to the lower surface  14   b  of the disk  14 . As further shown, a circular cutout  21  is formed in the lower shell  24  to provide access to the disk hub  16 . Preferably, the inner surfaces  22   a,    24   a  of the upper and lower shells  22 ,  24  are substantially planar. 
     A first non-woven fabric liner  26  is attached to the inner surface  22   a  of the upper shell  22 . The liner  26  is formed of a mixture of non-woven fibers bonded together in any well known manner, such as thermally, with an adhesive binder, or through a hydroentangling process. As used herein and in the claims, the term “bonded” is intended to cover all such possibilities. In the cartridge of U.S. Pat. No. 5,677,818, the liner  26  is formed of a mixture of rayon (80%) and nylon (20%) fibers. One fabric liner which has been used is “DataProtech Liner”, available from Veratec Data Resources Group, 100 Elm Street, Walpole, MA 02081-1898. The “DataProtech Liner” has a standard weight of 30.0 GSY, a nominal thickness of 7.8 mils, and a standard dry “MD” tensile strength of 5.0 lb/in. 
     When the fabric liner  26  is affixed to the inner surface  22   a  of the upper shell  22 , the main body  26   a  of the liner is spaced from the disk, in facing relation thereto, a predetermined distance, D. The main body  26   a  of the liner does not contact the upper surface  14   a  of the disk  14 . Preferably, the predetermined distance, D, is in the range of 0.2 to 0.8 mm. The predetermined distance, D, is approximately 0.5 mm. 
     A region of the fabric liner is subjected to a fuzzing process (described in U.S. Pat. No. 5,677,818) in which some of the bonded fibers in that region are loosened to form a region of upstanding fibers  26   b  that extend from the main body  26   a  of the liner to the surface  14   a  of the disk  14 , as shown in FIG.  2 . The upstanding fibers  26   b  contact the surface  14   a  of the disk and wipe any undesirable contaminants from the disk surface  14   a  as the disk  14  rotates in the casing  12 . The main body  26   a  of the liner  26 , however, remains spaced from the surface of the disk. With only the upstanding fibers  26   b  contacting the surface of the disk, drag on the disk is extremely low. Additionally, the upstanding fibers  26  wipe the disk without the need for conventional lifters and/or ribs to press the liner against the disk surface. Accordingly, the cartridge  10  of the present invention requires less components and is easier to manufacture. As can be appreciated, the upstanding fibers resulting from the fuzzing process must extend from the main body of the liner at least a distance equal to the predetermined spacing, D. 
     As further shown in FIG. 2, a second fabric liner  28 , which may be identical to the first liner  26 , is attached to the inner surface  24   a  of the lower shell  24 . Like the first liner  26 , the second liner  28  has a region of upstanding fibers  28   b  which extend from the main body  28   a  of the liner  28  to the lower surface  14   b  of the disk  14 . The upstanding fibers  28   b  of the second liner  28  function identically to those of the first liner. The enlarged cross-sectional view of a portion of the second liner  28  provides further detail illustrating the bonded fibers of the main body  28   a  of the liner, as well as the upstanding fibers  28   b  resulting from the fuzzing of the liner in accordance with the present invention. It has been found that use of the opposing fuzzed liners in accordance with the preferred embodiment of the present invention has a tendency to stabilize the disk  14  during high speed rotation (e.g., 3600 rpm). Stabilization of the rotating media is desirable. Additionally, because the upstanding fibers are not densely packed together, they can also serve to filter the air within the cartridge. 
     The first and second liners  26 ,  28  are attached to the respective planar surfaces  22   a,    24   a  of the upper and lower shells  22 ,  24  using an adhesive  29 . Specifically, an adhesive that cures under exposure to ultra-violet light is printed on the inner surfaces  22   a,    24   a  of the upper and lower shells  22 ,  24  using conventional pad printing technologies with a flat transfer pad. The liners  26 ,  28  are then placed on the respective shell surfaces  22   a,    24   a.    
     FIGS. 3 and 4 show further details of the inner surfaces  22   a,    24   a  of the upper and lower shells  22 ,  24 , respectively. As shown in FIG. 3, the inner surface  22   a  of the upper shell  22  is substantially planar, and the main body  26   a  of the first fabric liner  26  is affixed to the inner surface  22   a  of the upper shell  22  so that it lies substantially flat against the planar surface  22   a.  An opening  30   a  is provided in the front edge  20   a  of the upper shell  22 , and a groove  32   a  is formed in the upper shell  22  that extends from the opening  30  toward the center of the shell  22 . 
     As shown in FIG. 4, the inner surface  24   a  of the lower shell  24  is also substantially planar, and the main body  28   a  of the second fabric liner  28  is affixed to the inner surface  24   a  of the lower shell  24  so that it too lies substantially flat against the planar surface  24   a.  As further shown, the lower shell  24  includes an opening  30   b  and a groove  32   b  similar to that formed in the upper shell  22 . A circular opening  21  in the lower shell  24  provides access to the hub  16  of the disk  14 . 
     The opening  30   a  and groove  32   a  in the upper shell  22   a  cooperate with the opening  30   b  and groove  32   b  in the lower shell to provide the magnetic heads (not shown) of a disk drive with access to the recording surface(s) of the disk  14 . As FIGS. 3 and 4 illustrate, according to an important feature of the cartridge  10  of the present invention, there is no aperture or opening in either the upper or lower shell surfaces. Rather, the grooves  32   a,    32   b  form a closed channel within the cartridge. The only aperture through which the magnetic heads of a disk drive can enter the cartridge is that formed on the front edge  20  of the cartridge  10  by the respective openings  30   a  and  30   b.  By providing an aperture only in the front edge  20  of the cartridge, the risk of contaminants entering the cartridge and reaching the recording surface of the disk  14  is reduced. 
     FIGS. 3 and 4 further illustrate the sizes and shapes of the fuzzed regions  26   b,    28   b  (shaded portions) of the first and second liners  26 ,  28 . As shown, in the preferred embodiment, the fuzzed regions  26   b,    28   b  of each liner  26 ,  28  occupy approximately fifty percent (50%) of the liner surface area. 
     In accordance with the present invention the liner  28  is a polyester material which has unique characteristics which give the disk cartridge improved operating characteristics. The fibers of the liner of the present invention are shown in FIGS. 5 and 6. The single fiber of FIG. 5 is round and has a diameter of approximately 12 microns. The round fibers vary in diameter along the length of each fiber. As shown in FIG. 5, the fiber has a reduced diameter in the region  30  which is approximately 9 microns in diameter. These reductions in diameter appear irregularly over the fiber lengths as is shown in FIG.  6 . 
     The reductions in diameter are preferably approximately 25%. Reduction in the range of approximately 10% to approximately 50% produce improved results. 
     FIG. 7 shows a regular polyester fiber  32  next to a rayon fiber  34 . The polyester fiber is relatively smooth as is the rayon fiber. Moreover, the rayon fiber is not circular in cross-section. 
     FIG. 8 depicts the normal polyester fiber which is typically used as liner material. 
     FIG. 9 depicts rayon fiber which has been used as disk liner material. 
     The following tests and results show the improved operating characteristics which have been obtained with polyester liner material having fibers which are round and have irregularities as shown in FIGS. 5 and 6. The test which is performed where the interaction between liner and the disk is maximized is called the Spin-up-Spin-down test. In this particular test the drive will spin up to the operational speed. After the drive reaches the steady operating speed, the recording head will access a random location on the disk before parking again. The drive will then spin down to zero rpm. Since the disk is flexible in this case, substantial contact between the disk and the liner occurs during the spin-up-spin-down cycle. The interaction between the prior art polyester liner and disk will produce a substantial amount of contamination on the disk surface which could lead to increased error rate. Similar testing done with the liner made with rough polyester in accordance with the present invention, however, produces no or very slight contamination of the disk surface. 
     The table below summarizes the visual inspection result at the end of a comparative Spin-up-Spin-down test between the two liner types. Clearly, the liner in accordance with its present invention is much better in comparison to the prior art polyester liner. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                   
                   
                 Ranking of 
               
               
                 Sample 
                 Liner Type 
                 Contamination 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 Prior Art 
                 8 
               
               
                 2 
                 Prior Art 
                 9 
               
               
                 3 
                 Prior Art 
                 8 
               
               
                 4 
                 Prior Art 
                 8 
               
               
                 5 
                 Prior Art 
                 7 
               
               
                 average 
                   
                 8 
               
               
                 6 
                 Per Invention 
                 0 
               
               
                 7 
                 Per Invention 
                 1 
               
               
                 8 
                 Per Invention 
                 1 
               
               
                 9 
                 Per Invention 
                 0 
               
               
                 10  
                 Per Invention 
                 0 
               
               
                 Average 
                   
                 0.4 
               
               
                   
               
             
          
         
       
     
     A particular embodiment has been shown and described but various modifications are within the true spirit and scope of the invention. The appended claims cover all such modifications.