Abstract:
A flexible data storage card and shutter lock is disclosed. The flexible data storage card includes a housing, a media disc, a shutter, and a shutter lock. The housing includes a card top coupled to a base to define an enclosed region, and an access window defined by the base and communicating with the enclosed region. The media disc is rotatably disposed within the enclosed region. The shutter is slidably disposed within the enclosed region and defines a shutter window selectively alignable with the access window. The shutter lock is disposed within the enclosed region and is selectively couplable with the shutter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The subject matter of this application claims priority under 35 U.S.C. §119(e) to the subject matter of U.S. Provisional Patent Application No. 60/547,708, filed Feb. 25, 2004, which is incorporated herein by reference. 
     
    
     THE FIELD OF THE INVENTION  
       [0002]     The present invention relates to flexible data storage cards. More particularly, it relates to a shutter lock for a flexible data storage card.  
       BACKGROUND OF THE INVENTION  
       [0003]     Data storage media have been used for decades in the computer, audio, and video fields. Data storage media continue to be employed for storing large volumes of information in a form suited for subsequent retrieval and use.  
         [0004]     Data storage media are generally provided in one of two forms, long strands of magnetic tape and rotating discs. The rotating disc storage media are of two types: hard disc (HD) media and floppy disc (FD) media. Generally, HD media are maintained within a housing of a data storage device. For example, HD media are commonly maintained within a computer hard drive and accessed via an internal read/write device of the drive. In contrast, FD media are removable from, and interchangeable between, data storage devices. In this regard, FD media have the benefit of being transportable.  
         [0005]     HD media typically comprise rigid discs formed of a metal substrate having a sputter deposition of a magnetic film. Deposition of the magnetic film in this manner permits a very high magnetic recording density to be achieved. During a read/write operation, the HD media are rotated at relatively high speeds (i.e., approximately 10,000 rpm) and “fly” over the read/write head in a non-contact manner.  
         [0006]     FD media typically are composed of a plastic substrate, such as polyester, that is coated with a slurry of magnetic particles. The FD media can be coated on both sides to form “two-sided” media. In any regard, FD media operate at relatively low speeds (i.e., less than 1000 rpm) and the read/write head contacts the FD media. To facilitate good wear characteristics, the magnetic slurry contains a binder and a bulk lubricant along with the magnetic particles. Commonly, FD media are provided to users in an industry-accepted format, such as 3.5 inch floppy discs. While universally accepted, these formats are not convenient to handle and carry, have limited storage capacity, and do not provide durable protection for the FD media.  
         [0007]     More recently, efforts have been made to provide a conveniently sized, robust storage media offering advantages of both the HD and FD media. In particular, a transportable data storage card having a form factor of approximately the size of a credit card has been developed that includes a flexible, one-sided data storage media in the form of a disc. Such a device is known as a “flexible data storage card” and has mechanical flexibility in both the longitudinal and transverse directions. A flexible data storage card available from StorCard, Inc., San Jose, Calif. under the trademark StorCard® is one example.  
         [0008]     Generally, the StorCard® flexible data storage card consists of an outer shell or housing that maintains the flexible media disc. The housing normally includes a separate cover and a separate base that encloses the flexible media, fabric liners, and other components. The cover is known as a card top and is formed of a plastic laminate and includes an integrated circuit that monitors the flow of data into, and out of, the flexible data storage card. The base is a thin metallic structure that is laminated to the card top to form the housing. A window is provided on the base and includes a shutter that provides selective access to the flexible media disc by an external read/write head.  
         [0009]     During use, the shutter is displaced to provide access to the rotating flexible media disc by the read/write head. In this regard, the shutter is slideably mounted inside the housing. When the shutter is in the open position, the shutter window and the access window align, thus exposing the media disc. When not in use, the shutter is shunted to a closed position. It is possible, however, that taps or bumps to the housing may cause the shutter to be jostled to the open position. The inadvertent opening of the shutter may give rise to a risk of dust and debris entering into the housing, thus mitigating the protective purpose of the shutter. Debris present on the media disc has the potential to cause read/write errors and other failures. In addition, the build-up of debris in and near the shutter mechanism can interfere with the sliding of the shutter.  
         [0010]     Flexible data storage cards offer high capacity memory storage in a flexible and transportable format. The popularity of flexible data storage cards is ever increasing. However, shutters that open inadvertently can be a conduit for dust and debris to the media disc, and may possibly decrease the useful life of the storage card. Accordingly, a need exists for a flexible data storage card having an improved shutter mechanism.  
       SUMMARY OF THE INVENTION  
       [0011]     One aspect of the present invention relates to a shutter assembly for use in a flexible data storage card. The shutter assembly includes a shutter layer defining a trace, a shutter slidably disposed within the trace, and a magnetically responsive shutter lock coupled to the shutter layer. In this regard, the shutter lock is selectively couplable with the shutter between an engaged state and a disengaged state.  
         [0012]     Yet another aspect of the present invention relates to a method of restricting lateral movement of a shutter disposed in a flexible data storage card. The method includes forming a detent on the shutter, and providing a shutter lock including a pawl disposed in the flexible data storage card. The method additionally includes selectively engaging the pawl of the shutter lock with the detent of the shutter.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Embodiments of the invention are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.  
         [0014]      FIG. 1  is a perspective, exploded view of a flexible data storage card including a shutter assembly according to one embodiment of the present invention;  
         [0015]      FIG. 2  is a top plan view of a shutter of the shutter assembly shown in  FIG. 1  according to one embodiment of the present invention;  
         [0016]      FIG. 3  is a top plan view of a shutter lock of the shutter assembly shown in  FIG. 1  according to one embodiment of the present invention;  
         [0017]      FIG. 4  is a top plan view of the shutter assembly showing the shutter lock engaged with the shutter according to one embodiment of the present invention; and  
         [0018]      FIG. 5  is a top plan view of the shutter assembly in the presence of a magnetic field and showing the shutter lock disengaged with the shutter according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     A simplified exploded, perspective view of a flexible data storage card that is representative of data storage cards advertised under the trademark StorCard® and according to one embodiment of the present invention is illustrated at  20  in  FIG. 1 . The flexible data storage card  20  includes a housing  22 , a media layer  24 , a flexible media disc  26 , and a shutter assembly  28 .  
         [0020]     The housing  22  is sized to be transportable and has a form factor that approximates the size of a credit card. Thus, the housing  22  has a size of approximately 86 mm×54 mm×0.8 mm, although other dimensions are also acceptable. With this in mind, a card top  40  and a base  42  combine to define the housing  22 . In one embodiment, the card top  40  forms a cover and the base  42  forms a bottom. However, as used though out the specification, directional terminology such as “cover,” “base,” “upper,” “lower,” “top,” “bottom,” etc., is employed for purposes of illustration only and is in no way intended to be limiting.  
         [0021]     The card top  40  and the base  42  are reciprocally mated to one another and are generally rectangular. The card top  40  defines an exterior surface  44  and an interior surface  46 . In one embodiment, an electronic chip  48  is mounted to the exterior surface  44  of the card top  40  and controls the flow of data to and from the media disc  26 .  
         [0022]     The card top  40  is generally flexible. In one embodiment, the card top  40  is a thin laminate of plastic and metal layers. In another embodiment, the card top  40  and the base  42  are each formed from a single, thin metallic layer. As an example, in one embodiment the card top  40  and the base  42  are each formed from a single metallic layer having a thickness of about 0.003 inch, such that when assembled, the housing  22  is flexible. After assembly, the flexible data storage card  20  is transportable, and can be, for example, carried in a wallet and flexed in both the transverse and longitudinal directions without damaging the flexible media disc  26 .  
         [0023]     The base  42  defines an exterior surface  50  and an interior surface  52 . In addition, the base  42  defines an access window  54  and a shutter pin slot  56 . The access window  54  is configured to permit access by a read/write head (not shown) to the flexible media disc  26 . The shutter pin slot  56  is configured for access by a drive pin (not shown) of a drive (not shown) during a read/write process, as more fully described below.  
         [0024]     The media layer  24  is generally a single layer of flexible material and defines a circular hole  60  configured to receive the flexible media disc  26 . In this regard, the media layer  24  retains the flexible media disc  26  in a desired orientation within the housing  22  and forms an offset between the shutter assembly  28  and the card top  40 .  
         [0025]     The flexible media disc  26  (hereinafter media disc  26 ) is of a type known in the art and generally includes a thin sheet of polyester or similar material having a non-media side  70  opposite a media side  72 . In this regard, in one embodiment the media side  72  is coated with a magnetic layer configured to magnetically record and store information. In general, the non-media side  70  is not coated with a magnetic layer, although the non-media side  70  can include one or more other coatings (i.e., a lubricating layer and/or and anti-static layer). For example, in one embodiment the media disc  26  is a thin sheet of polyester approximately 0.003 inch thick and includes a slurry-coated layer of magnetic particles on the media side  72 .  
         [0026]     The shutter assembly  28  includes a shutter layer  78  that defines a trace  80  (i.e., a cutout), a shutter  82 , and a shutter lock  84 . The shutter layer  78  is generally a flexible layer, and in one embodiment is a single layer of thin metal. In another embodiment, the shutter layer  78  is a flexible laminate of metal and/or plastic layers. In any regard, the shutter layer  78  defines the trace  80  that is otherwise a cutout formed in the shutter layer  78  sized and configured to receive the shutter  82  and the shutter lock  84 . To this end, the shutter  82  is slidably retained within the trace  80 , and the shutter lock  84  is cantilevered from the shutter layer  78  and oriented to selectively couple with the shutter  82  between an engaged state and a disengaged state. In one embodiment, the shutter lock  84  is cantilevered from the shutter layer  78  at a perimeter of the trace  80 , as described below.  
         [0027]     In addition, the flexible data storage card  20  includes adhesive layers configured to assemble the various components described above into a unitary flexible data storage card  20 . In particular, first adhesive layer  90  is disposed between the media layer  24  and the interior surface  46  of the card top  40 . A second adhesive layer  92  is disposed between the media layer  24  and the shutter assembly  28 . A third adhesive layer  94  is disposed between the shutter assembly  28  and the inner surface  52  of the base  42 . In one embodiment, each of the adhesive layers  90 ,  92 , and  94  defines a gasket-like spacer that provides a clearance within the assembled housing  22  for movement of the rotatable media disc  26  and the slidable shutter  82 .  
         [0028]      FIG. 2  is a top plan view of the shutter  82 . The shutter  82  includes a shutter body  100 , a shutter arm  102  extending from the shutter body  100 , and a shutter leg  104  extending from the shutter body  100  opposite the shutter arm  102 .  
         [0029]     The shutter body  100  defines a shutter window  106  and a hub window  108 . The shutter window  106  is sized for alignment with the access window  54  ( FIG. 1 ) when the shutter  82  is disengaged from the shutter lock  84  ( FIG. 1 ) and activated to an open position by a drive (not shown).  
         [0030]     The shutter arm  102  extends from the shutter body  100  and defines a detent  110  and a pin aperture  112 . The detent  110  is preferably formed as a part of the shutter arm  102 , although the detent  110  could be defined by the shutter body  100  or by the shutter leg  104 . In any regard, the detent  110  defines at least one engagement surface  114  configured to engage with the shutter lock  84  ( FIG. 1 ) and impede lateral movement of the shutter  82 , thus maintaining the shutter  82  in the closed position. The term detent is employed in this detailed description to include any surface suited for being a latching and/or engagement surface. With this in mind, the term detent includes cavities (i.e., slots or depressions), or protrusions (i.e., peaks) defined in the shutter  82 , and preferably defined by the shutter arm  102 . The pin aperture  112  is generally a circular hole defined in the shutter  82 , and preferably defined by the shutter arm  102 . A drive pin (not shown) of the drive (not shown) inserts into the pin aperture  112  in activating the disengaged shutter  82  to the open position.  
         [0031]     The shutter leg  104  extends from the shutter body  100  opposite the shutter arm  102  and is configured to slide within the trace  80  ( FIG. 1 ) in guiding and balancing the shutter  82  between the open and closed positions. In one embodiment, the mass of the shutter leg  104  counterbalances any force acting on the engagement surface  114  and/or the shutter arm  102  when the shutter lock  84  ( FIG. 1 ) couples into the detent  110 . In other words, in one embodiment the shutter leg  104  stabilizes the shutter  82  by balancing moment forces as the shutter lock  84  couples with the shutter  82  between the engaged and disengaged states.  
         [0032]     The shutter  82  is generally formed of a thin and flexible material that is unaffected by magnetic forces. In one embodiment, the shutter  82  is formed of a single layer of metal approximately 0.004 inch thick. In another embodiment, the shutter  82  is formed of plastic. In any regard, in a preferred embodiment the shutter  82  is formed of material having a low magnetic permeability such that the shutter  82  is relatively unresponsive to magnetic field forces. For example, in one embodiment the shutter  82  is formed of a stainless steel having a relative magnetic permeability of less than 50, and preferably, the shutter  82  is formed of a  316  stainless steel having a relative magnetic permeability of approximately 10. In this regard, the relative magnetic permeability is defined to be a ratio of the magnetic permeability of the material (often expressed in units of Newtons per ampere squared) to the magnetic permeability of air (often expressed in units of Newtons per ampere squared), such that the relative permeability is a dimensionless number.  
         [0033]      FIG. 3  is a top plan view of the shutter lock  84  according to one embodiment of the present invention. The shutter lock  84  includes a base  120 , a lever  122  extending from the base and terminating in an end  128 , and a leg  124  extending from the base  120  and terminating in a pawl  126 . In one embodiment, the lever  122  extends from the base  120  in the range of 0.25 inch to 1.0 inch, preferably the lever  122  extends from the base  120  by approximately 0.5 inch; and the leg  124  extends from the base  120  in the range of 0.5 inch to 1.5 inch, preferably the leg  124  extends from the base  120  a length of approximately 0.75 inch.  
         [0034]     The lever  122  is generally formed to have a low inertia such that the lever  122  will deflect in the presence of a magnetic field. In this regard, in one embodiment the lever  122  defines a leaf spring having a width D 1  of between 0.005 inches to 0.02 inches, and preferably the lever  122  has a width D 1  of approximately 0.008 inches, although other dimensions are also acceptable.  
         [0035]     The base  120  is generally much more massive than the lever  122 , and thus the base  120  has greater inertia than the lever  122 . In one embodiment, the base  120  defines a width D 2  of between 0.05 inches to 0.10 inches, and preferably the base  120  has a width D 2  of approximately 0.08 inches, although other dimensions are also acceptable. In this manner, the base  120  is approximately an order of magnitude more massive than the lever  122 .  
         [0036]     The pawl  126  is disposed on an end of the leg  124  opposite the base  120 . The pawl  126  defines at least one engagement surface  130  configured to lock (i.e., engage) with the engagement surface  114  defined by the detent  110  ( FIG. 2 ). In one embodiment, a cross-section of the pawl  126  defines a generally rectangular plan form. In an alternate embodiment, a cross-section of the pawl  126  defines a generally triangular plan form.  
         [0037]     The shutter lock  84  is preferably formed of a single layer of metal having a thickness of approximately 0.004 inches and a high magnetic permeability. In a preferred embodiment, the shutter lock  84  is formed of soft steel having a relative magnetic permeability of greater than 300. In one embodiment, the shutter lock  84  is formed of 1095 spring steel having a relative magnetic permeability of approximately 1000. With this in mind, in one embodiment, the relative magnetic permeability of the shutter lock  84  is at least one order of magnitude (i.e., ten times) greater than the relative magnetic permeability of the shutter  82  ( FIG. 2 ), and more preferably, the relative magnetic permeability of the shutter lock  84  is at least two orders of magnitude (i.e., one-hundred times) greater than the relative magnetic permeability of the shutter  82 . With this in mind, the shutter lock  84  is generally responsive to (i.e., movable by) magnetic fields, whereas the shutter  82  is not responsive to magnetic fields.  
         [0038]      FIG. 4  is a top plan view of the shutter assembly  28  showing the shutter  82  slidably retained within the trace  80  of the shutter layer  78  and engaged by the shutter lock  84 . For ease of illustration and descriptive clarity, the shutter assembly  28  will be discussed apart from the other components of the flexible data storage card  20  ( FIG. 1 ), although one of skill in the art of flexible data cards will understand that the following description is consistent with a shutter assembly  28  in an assembled flexible data storage card  20 .  
         [0039]     As a point of reference, the shutter  82  is in a closed position relative to the shutter layer  78  such that the media disc  26  ( FIG. 1 ) is not exposed to the access window  54  ( FIG. 1 ). In other words, the shutter window  106  is not aligned with the access window  54 . The shutter lock  84  is disposed within the trace  80  and is cantilevered from the shutter layer  78  at a perimeter of the trace  80 . In particular, the end  128  of the lever  122  is coupled to the shutter layer  78  at a perimeter of the trace  80 . In this manner, the end  128  is essentially fixed in place relative to the shutter layer  78  thereby confining the lever  122  (and also the shutter lock  84 ) within the trace  80 , such that movement of the pawl  126  is restricted to one direction (vertically in the Y-direction relative to  FIG. 4 ). In addition, the shutter  82  is slidably retained within the trace  80  and restricted to lateral movement (horizontally in the X-direction relative to  FIG. 4 ) along a longitudinal axis of the shutter  82 . Further, the pawl  126  is engaged with the detent  110 , such that the engagement surface  130  of the pawl  126  nests with the engagement surface  114  of the detent  110 . In this manner, the shutter  82  is impeded from sliding within the trace  80  such that lateral movement of the shutter  82  is restricted or completely eliminated.  
         [0040]      FIG. 5  is a simplified schematic view of the shutter assembly  28  as inserted in a drive  140  according to one embodiment of the present invention. While one of skill in the art of flexible storage cards will understand that the entire flexible data storage card  20  ( FIG. 1 ) is actually inserted into the drive  140 , a full appreciation of the present invention can be gathered with reference to the interaction between the shutter assembly  28  and the drive  140 , as depicted in  FIG. 5 . Therefore, the shutter assembly  28  will be discussed apart from the other components of the flexible data storage card  20 , in a manner similar to the description presented for  FIG. 4  above. With this in mind, the drive  140  includes a magnetic field source  142  and a drive pin  144 . The magnetic field source  142  emanates a magnetic field B, and the drive pin  144  is coupled to the pin aperture  112  of the shutter  82  upon insertion of the data storage card  20  into the drive  140 .  
         [0041]     The shutter  82  is illustrated in  FIG. 5  in an open position. In one exemplary embodiment, as the flexible data storage card  20  ( FIG. 1 ) is inserted into the drive  140  for read/write purposes, the magnetic field source  142  causes the shutter lock  84  to move to a disengaged state relative to the shutter  82 . In particular, the magnetic field B acts upon the magnetically permeable shutter lock  84  and attracts the shutter lock  84  to the source  142 . Specifically, the pawl  126  deflects in the Y-direction (shown in  FIG. 4 ), disengaging from the detent  110 , as the lever  122  deflects, thus ensuring essentially linear movement of the pawl  126 . Simultaneously, the drive pin  144  physically couples with the pin aperture  112  via the shutter pin slot  56  ( FIG. 1 ). Thereafter, the drive pin  144  displaces the disengaged shutter  82  to the open position (as shown). In this manner, the shutter lock  84  can be selectively and magnetically activated between an engaged state ( FIG. 4 ) and a disengaged state ( FIG. 5 ) in facilitating movement of the shutter  82  between the closed position ( FIG. 4 ) and the open position ( FIG. 5 ).  
         [0042]     The magnetic field B can be any magnetic field, for example an electro-magnetic field or a magnetic field created by a permanent magnet. In one embodiment, the magnetic field source  142  can be switched on and off. With this in mind, in the absence of the magnetic field B, the shutter lock  84  occupies a zeroth energy state (i.e., the shutter lock  84  is not deflected) and is engaged with the shutter  82 . In contrast, when the magnetic field B is present (or “on”), the shutter lock  84  responds to the magnetic field B and the pawl  126  is displaced away from the detent * 110 , thus permitting lateral movement of the shutter  82  within the trace  80 .  
         [0043]     In one embodiment, the magnetic field source  142  is a permanent magnet disposed in a card reader, such as a StorPod® brand reader available from StorCard, Inc., San Jose, Calif. In one embodiment, the magnetic field source  142  activates the shutter lock  84  to the disengaged state whenever the flexible data storage card  20  ( FIG. 1 ) is inserted into the drive  140 , for example, the StorPod® brand reader. Consequently, removal of the flexible data storage card  20  from the drive  140  returns the shutter  82  to the closed position and interrupts the effect of the magnetic field B on the shutter lock  84  such that the shutter lock  84  returns to reside in the stable zeroth energy state (i.e., the shutter lock  84  engages with the shutter  82 ).  
         [0044]     Magnetic fields B of large magnitude can potentially interfere with data stored on the media disc  26  ( FIG. 1 ). For this reason, it is desired that the magnetic field B employed to activate the shutter lock  84  be of a magnitude that is incapable of writing over the data stored on the media disc  26 . In this regard, it is preferred that the shutter lock  84  be responsive to magnetic fields B of relatively small magnitude (i.e., that the shutter lock  84  have a high relative magnetic permeability), and that the shutter  82  be relatively unresponsive to magnetic fields B of relatively small magnitude (i.e., that the shutter  82  have a low relative magnetic permeability). As described above, therefore, in one embodiment the relative magnetic permeability of the shutter lock  84  is at least ten times greater than the relative magnetic permeability of the shutter  82 , and preferably, the relative magnetic permeability of the shutter lock  84  is at least two orders of magnitude (i.e., one-hundred times) greater than the relative magnetic permeability of the shutter  82 .  
         [0045]     Although specific embodiments have been illustrated and described for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the chemical, mechanical, electromechanical, electrical, and computer arts will readily appreciate that the present invention may be implemented in a variety of embodiments. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is intended that this invention be limited only by the appended claims and their equivalents.