Abstract:
A cartridge for a magnetic disk drive having a clamping mechanism which is actuated as the door to the cartridge is closed is disclosed. The cartridge is closed when he cartridge is removed from the drive. The door covers the opening through which the cartridge is accessed by read/write heads. When the cartridge is removed from the drive, the mechanism of the present invention clamps the recording disk against the cartridge shell to prevent rattle, which might otherwise damage the recording disk. The mechanism includes a rotating cam having helical lobes, a translating cam having helical slots to receive the lobes, a spring to bias the door and a spring to bias the rotating cam.

Description:
This Application is a continuation of U.S. provisional Application Ser. No. 09/139,608 filed Aug. 25, 1998 (Iom-9470) now U.S. Pat. No. 6,141,185. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to data recording drives and, more particularly, to a removable cartridge for disk drives that contains a mechanism that restrains the cartridge disk/hub assembly when the cartridge is not in use. 
     BACKGROUND OF THE INVENTION 
     Magnetic disk drives which write and read digital data from flexible magnetic disks are wide spread. “Floppy disk drives” have been extensively used for small, so-called microcomputer systems, for word processing applications and the like. The flexible disk cartridge includes a relatively thin, flexible jacket which is inserted into the floppy disk drive. 
     Rigid disk drives, such as the Model 3350 produced by IBM Corporation, usually have a fixed rigid magnetic media. The magnetic heads do not contact the magnetic surface, but ride on a thin film of air. Because of this, and other features, these disk drives are capable of extremely precise and high speed operation. This type of disk drive is commonly referred to as a “Winchester” drive. 
     “Bernoulli” disk drives having performance characteristics similar to that of Winchester drives, but with removable cartridges, have been developed. A flexible magnetic disk is enclosed in a rigid box which is normally completely closed. U.S. Pat. No. 4,400,748 to Bauck et al. and related patents that are assigned to the assignee of the present invention describe drives using Bernoulli flexible disks. U.S. Pat. No. 4,901,173 to Jones et al. Also, related patents that are assigned to the assignee of the present invention describe improvements which relate to so-called “half height drives.” 
     Rigid disks enclosed in a rigid, removable cartridge, or shell have also been used. U.S. Pat. No. 4,864,452 to Thompson et al. is an example of such a drive. 
     The JAZ™ drive that is manufactured and sold by the assignee of the present invention, like a Winchester type drive, stores data on rigid recording media. 
     Removable cartridges that are used with such drives typically have a door which closes the cartridge when it is removed from the drive. The door prevents contamination on the magnetic recording medium when the cartridge is not in the drive. When the cartridge is inserted into the drive, the door slides to an open position to provide access for the magnetic recording heads to engage the recording medium. 
     When the cartridge is removed from the drive, it is often subject to rough handling. During handling, physical contact of the disk with the shell may damage the disk, particularly if the disk and cartridge shell are subject to excessive “rattling”. 
     U.S. Pat. No. 5,650,899 to Schick (&#39;899” patent), which is assigned to the assignee of the present invention and incorporated herein by reference in its entirety, shows a non-rattling mechanism for removable cartridges. The cartridge shown in the &#39;899 patent, which is used with a magnetic disk drive, has a clamping mechanism that is actuated as the door to the cartridge is opened and closed. When the door closes, the mechanism clamps the recording medium against the cartridge shell to prevent the disc from rattling inside the housing, which might otherwise damage the recording disk. When the door opens, the mechanism retracts to free the disk to rotate. 
     Typically, the door of the &#39;899 patent cartridge was not self-closing, but rather required a mechanical mechanism within the drive to physically close the door. If the mechanical closing mechanism did not close the door, or if a user opened the door by hand outside of the drive, then the disk is exposed to contaminants. 
     It is an object of the present invention to provide a device which clamps the disk to the cartridge shell when the cartridge is removed from the drive to prevent rattling of the cartridge, which has sufficient strength to close the cartridge door, and which is easy to assemble. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a clamping mechanism in a data storage cartridge is actuated when the cartridge is removed from the drive. The mechanism restrains the recording medium to prevent rattling. 
     The clamping mechanism is driven by the motion of the sliding door. When the door is in a closed position (which corresponds to the cartridge disposed out of the drive) the mechanism expands or extends to restrain the media from rattling inside the cartridge during handling. When the door is in an opened position (which corresponds to the cartridge disposed inside of the drive) the mechanism contracts such that it is free of the hub and the media is free to rotate. 
     The clamping mechanism includes a rotating cam which rotates in around same axis as the media, a translating cam follower, a door spring, a rotating cam spring, and an arm, which connects the rotating cam to the motion of the sliding cartridge door. The mechanism is mounted on a post in the cartridge top shell half. The clamping mechanism is situated in the cavity formed inside the media hub. The door spring is a torsion spring that is disposed around the post. The door spring has sufficient strength to pivot the door to its fully closed position. The rotating cam spring, which is also disposed around the post, provides torsion to pivot the rotating cam to its clamped state, also referred to herein as its rest state or locked state, that exists while the door is fully closed. The rotating cam has spiral radial lobes that cooperate with spiral slots in the translating member. A rotating cam spring urges the cam actuation. 
     The mechanism is attached to the sliding door by means of a bent wire which slides in a slot in the end of an arm which pivots about the axis of the recording media. In a preferred embodiment, a member, which is rotatable about the axis of the recording medium, has an arm connected to the door and attaches the sliding door to the mechanism. A wire in an opening in the terminal end of the arm telescopes into and out of the opening as the door travels through its stroke. This provides compliance to account for relative changes in the distance between the mechanism and sliding door attachment point as the door travels through its stroke. A door spring actuates the door via the bent wire. 
     The mechanism has two states; locked and unlocked, which correspond respectively to the door closed and door opened states. In the locked state, the translating cam follower applies a force against the media hub effectively trapping the hub against the cartridge bottom shell. This force is sufficient to prevent the media from rattling against the cartridge shell halves when out of the drive. In the unlocked state, the translating cam does not contact the hub to allow the media to spin freely when coupled to a spindle motor. 
     The foregoing and other objects, features and advantages of the invention will be better understood from the following more detailed description and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings which are incorporated in and constitute a part of the specification, illustrate the preferred embodiment of the invention and together with the description, explain the principles of the invention. The invention will now be further described by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 shows a top view of the cartridge; 
     FIG. 2 shows a front view of the cartridge with the door closed; 
     FIG. 3 is a bottom perspective view with a portion of the bottom shell and recording media removed to show the cams; 
     FIG. 4 is another perspective view of the embodiment shown in FIG. 3 showing; 
     FIG. 5 is the view of the embodiment shown in FIG. 3 with the door removed for clarity; 
     FIG. 6 is a perspective view of the top section of the cartridge with the bottom section and clamping mechanism removed; 
     FIG. 7 is a perspective view of the top shell including the mounting post and door spring; 
     FIG. 8 shows the view of FIG. 7 with the rotating cam spring attached; 
     FIG. 9 shows the underside of the rotating cam with the rotating cam spring installed; 
     FIG. 10 is a perspective view of the top shell including the rotating cam; 
     FIG. 11 is a top view of the translating cam in the raised position; and 
     FIGS. 12A and 12B show the clamping mechanism in the locked, and unlocked positions, respectively. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-3 show a cartridge having two half shells  11  and  12  joined together at joint  13 . The cartridge has a front  14 , a back  15  and two sides  16  and  17  between substantially flat planar surfaces  18  and  19 . An opening  20  in the front of the cartridge provides access by the read/write heads to the recording disks  22 ,  22   a.    
     As best shown in FIG. 1, the cartridge has a protruding front  14  that preferably comprises substantially rectilinear portions that obliquely extend from sides  16  and  17 , and that yield to a radius portion near the center of front  14 . Pack  15 , sides  19  and  17 , and surfaces  18  &amp;  19  otherwise preferably form an approximate right parallelpiped. 
     The disks  22  and  22   a , a spacer  24 , a spindle hub  26 , and a bottom plate  25  comprise the media hub. A flexible door  23  covers the opening  20  (shown in FIG. 5) when the cartridge is removed from the drive. A hole in the bottom shell half allows access for a spindle motor to engage the bottom plate  25  of the media hub. Door arm  27 , which is attached to door  23 , is shown in the closed position in FIG.  3 . 
     The clamping mechanism  10  according to the present invention is actuated as the door  23  is opened and closed. The mechanism  10  includes a rotating cam  29  with three helical lobes  44 , and a translating cam  30  with three matching helical slots  46 . As best seen in FIGS. 1 and 10, each lobe  44  has an arcuate or spiral length “L” that is substantially greater than its longitudinal height “H”. The greater contact surface area created by such lobe shape, compared with prior art designs having cylindrical posts of diameter H, provides operational and manufacturing advantages. The terms “helical,” and “spiral” (and variations thereof) in this application and appended claims may refer to a curved shape (that is, wherein the lobe has a somewhat cup-like shape), a helical shape, or a straight shape obliquely oriented to the longitudinal axis (that is, wherein the lobes have a substantially constant slope). As used in the specification and appended claims, the terms “translating cam” and “translating cam follower” are synonymous. Both cams  29  and  30  are located coaxial to the media hub. Translating cam  30  is moved axially by the cam lobes  44  as the rotating cam  29  rotates. This axial movement clamps the media hub against bottom shell half  11  in the position shown in FIG.  3 . Mechanism  10  also includes a door spring  48  and a rotating cam spring  50 , as will be described below. 
     As shown in FIG. 4, door arm  27  is connected to the door  23  by a bent wire  28 . Wire  28  is slidably coupled to arm  27  to allow relative changes in the distance between door arm  27  and the end of door  23  as the door travels through its stroke, which enables clamping mechanism  10  to be employed with a door having a non-uniform radius. 
     As shown in FIG. 5, when the door  23  is moved to the open position, the door arm  27  and rotating cam  29  have been rotated counter clockwise, the translating cam  30  is fully retracted away from the media hub, and the media hub has moved away from the bottom half shell  11 , by the rotation of lobes  44  within slots  46 . The terms “clockwise” and “counter clockwise” as used herein are used relative to the particular Figure to which the discussion pertains. 
     FIGS. 6 and 7 show the top shell half  12  with an integral mounting post  31  on which mechanism  10  mounts. The hollow mounting post  31  is substantially coaxial to the media hub. Post  31  has flexible fingers formed by notches  34  in the post. Raised lips  32  on top of the post provide “snap” retention of the rotating cam  29 . A ring  33  coaxial to the media hub provides a rotating pivot surface for the door arm  27 . 
     As shown in FIGS. 7 and 8, a door spring  48  and a rotating cam spring  50 , each of the torsion spring-type, and disposed around post  31 . Door spring  48  has one end  49   a  engaged in a notch  34 . Another end  49   b  of door spring  48  is engaged on a tang  36  to provide torsion to urge arm  27  towards its closed position. Tang  36  is formed integral with door arm  27 . Cam spring  50  has one end  51   a  engaged in another notch  34  (opposite the notch in which the door spring end  49   a  is engaged). Another end  51   b  of cam spring  50  is engaged in a notch  52  disposed on the underside of rotating cam  29 , as shown in FIG.  9 . Cam spring  50  urges rotating cam  29  towards its rest position corresponding to the mechanism in the locked position. FIG. 7 shows cam spring  50  removed for clarity. 
     The wind direction of the torsion door spring  48  is such that it urges the door arm counter-clockwise toward the closed position. As shown in FIG. 9, rotating cam  29  has feet  40  disposed on the bottom thereof that slide inside slots  39  integrally formed in the plate that forms door arm  27  (as shown in FIG.  9 ). Slots  39  are approximately coaxial with the disk hub, and allow feet  40  on the bottom of rotating cam  29  to extend therethrough and contact the inside surface of the top shell half  12 . Slots  39  allow the rotating cam  29  to clamp the media hub while still allowing the door arm to rotate and close the door. 
     FIG. 10 shows the rotating cam  29  “snapped” into place over the lips  32  on the mounting post  31 . The rotating cam  29  is retained and guided radially at the top by mounting post  31  and at the bottom by the slots  39  in the door arm  27 . 
     FIG. 11 shows the translating cam  30  assembled on rotating cam  29 , in the raised or “door closed” position. The cross bar  41  of the translating cam  30  engages the notches  34  in the mounting post  31  to prevent rotation of the translating cam  30 . 
     Referring to FIGS. 12A and 12B, the operation of the mechanism according to the present invention will be described. FIG. 12A shows door arm  27  in its fully closed position. Lobes  44  of rotating earn  29  (biased by spring  50 ) are shown urging translating cam  30  upwards (relative to FIG. 12A) to the clamped state. The fully closed position of arm  27  results in translating cam  30  urging against the disk hub to clamp the disk hub to the cartridge housing  11 , as will be understood by those familiar with such cartridges. The disk hub and recording media are not shown in FIGS. 12A and 12B for clarity. 
     When the cartridge is inserted into a drive (not shown), a snag (not shown) disposed within the drive opens door  23  by catching on clip  57  (shown in FIG. 3) in a clockwise direction relative to FIGS. 3,  12   a , and  12   b . Motion of door  23  imparts rotation through wire  28  and arm  27  to pivot rotating cam  29 . FIG. 12B shows arm  27  in its fully open position. Rotating cam  29  has, therefore, been rotated clockwise such that lobes  44  engage slots  46  in translating cam  30 . The spiral arrangement of lobes  44  and slots  46  cause such clockwise rotation to draw translating member  30  toward rotating member  29  and top plate  12 , thereby freeing the disk hub (not shown in FIG. 12B) from the mechanism to enable the recording media to rotate. When use of the disk is no longer required, the door  23  may close by the torsion created by door spring  48 . Rotating cam spring  50  provides torsion to counter-clockwise pivot rotating cam  29  to its rest position that corresponds to a locked state. 
     The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.