Abstract:
An apparatus including a read head and at least two tape guides. The read head detects a magnetic field representative of information recorded on magnetic tape media, and the at least two tape guides guide the magnetic tape media on a path adjacent a read surface of the read head. The at least two tape guides are positioned to contact a substrate of the magnetic tape media and to maintain a non-zero distance between the path and the read surface.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    This application is directed generally and in various embodiments to an apparatus and a method for processing magnetic tape media. 
       BACKGROUND 
       [0002]    Magnetic tape media for recording and reproducing analog information is known and has been used extensively by the recording industry and others over the last several decades. Magnetic tape media is typically constructed of a magnetic layer bonded to a substrate by a binder layer. The magnetic layer may include, for example, magnetic oxide particles or other suitable type of magnetic particles formed into one or more tracks, and the binder layer may include a polymer binder. During the recording process, the magnetic tape media is passed over a write head which generates a time-varying magnetic field based on the analog information to be recorded. The magnetic field alters the polarity of magnetic particles, thereby “writing” the information to the magnetic tape media. The recorded information is subsequently reproduced by passing the magnetic tape media over a read head which detects a time-varying magnetic field created by the relative motion of the magnetic particles. The read head typically includes a coil which generates an analog signal representative of the recorded information in response to the time-varying magnetic field. 
         [0003]    Magnetic tape media is not suitable for storing analog information indefinitely, however. In particular, a variety of processes cause the binder layer and/or the substrate to physically degrade over time. Of particular concern is a process termed “hydrolysis” wherein moisture absorbed by the binder layer causes its deterioration and delamination from the substrate. Sometimes referred to as “sticky tape syndrome,” this condition may cause a portion of the magnetic layer and/or binder layer to shed and clog the read head and/or other components (e.g., tape guides and rollers) of the tape transport mechanism during reproduction, possibly rendering the affected portions of the tape media permanently unplayable and/or causing severe damage to the tape transport mechanism. 
         [0004]    In certain cases, magnetic tape media affected by hydrolysis may be “repaired” to an extent by heating the magnetic tape media for a period of time to stabilize the binder layer so that the recorded information may be reproduced and transferred to another recording medium. Although this “baking” process is generally effective, it nonetheless may be desirable to first ascertain and review the tape media content to determine if the time and expense of restoration is warranted. The need to ascertain and review the tape media content without baking is especially desirable in cases where a large amount of tape media of unknown content is being considered for restoration. 
       SUMMARY 
       [0005]    This application discloses an apparatus including a read head and at least two tape guides. The read head detects a magnetic field representative of information recorded on magnetic tape media, and the at least two tape guides guide the magnetic tape media on a path adjacent a read surface of the read head. The at least two tape guides are positioned to contact a substrate of the magnetic tape media and to maintain a non-zero distance between the path and the read surface. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0006]      FIG. 1  illustrates a magnetic tape media transport mechanism according to an embodiment of the present invention; 
           [0007]      FIGS. 2A and 2B  illustrate top views of a head stack mounting assembly according to various embodiments of the present invention; 
           [0008]      FIG. 3  illustrates a front view of the head stack mounting assembly of  FIG. 2A ; 
           [0009]      FIG. 4  illustrates a top view of the head stack mounting assembly of  FIG. 2A , and 
           [0010]      FIGS. 5A and 5B  illustrate top and front views, respectively, of the record head of the head stack mounting assembly. 
       
    
    
     DESCRIPTION 
       [0011]      FIG. 1  illustrates a magnetic tape media transport mechanism  5  according to one embodiment of the present invention. As shown, the transport mechanism  5  may employ a reel-to-reel configuration and include a supply tape reel spindle  10 , a take-up tape reel spindle  15 , a first tape guide  20 , a second tape guide  25 , a first roller guide  30 , a second roller guide  35 , a capstan/pinch roller assembly  40 , and a head stack mounting assembly  45 . Spindle  10  is configured to receive a supply tape reel  50  containing magnetic tape media  55  to be processed by the transport mechanism  5 , and spindle  15  is configured to receive a take-up tape reel  60  for receiving the magnetic tape media  55  subsequent to being processed. According to various embodiments, the magnetic tape media  55  may contain analog audio content, such as music or other sounds. In certain embodiments, the magnetic tape media  55  may be degraded by the effects of hydrolysis. 
         [0012]    The first and second tape guides  20 ,  25 , the first and second roller guides  30 ,  35 , the capstan/pinch roller assembly  40 , and the head stack mounting assembly  45  collectively define a tape path through which the magnetic tape media  55  is transported. At the beginning of the tape path, as shown in  FIG. 1 , magnetic tape media  55  is unwound from the supply tape reel  50  and introduced into the transport mechanism  5  such that the magnetic layer of the magnetic tape media  55  is outwardly guided over the first tape guide  20 . From the first tape guide  20 , the substrate of the magnetic tape media  55  is outwardly guided over the first roller guide  30 . The magnetic tape media  55  is next passed through the head stack mounting assembly  45  and then through the capstan/pinch roller assembly  40 . From the capstan/pinch roller assembly  40 , the substrate of the magnetic tape media  55  is outwardly guided over the second roller guide  35 . From the second roller guide  35 , the magnetic layer of the magnetic tape media  55  is outwardly directed over the second tape guide  25  and onto the take-up tape reel  60 . A DC motor (not shown) may rotate the capstan of the capstan/pinch roller assembly  40  such that the magnetic tape media  55  is metered through the tape path at an appropriate speed. Additionally, spindle  10  and/or the spindle  15  may be motorized such that the magnetic tape media  55  is properly tensioned and fed/collected by reels  50 ,  60 . 
         [0013]    In certain embodiments, the tape guides  20 ,  25  may be stationary pins constructed of a suitably non-magnetic material, such as, for example, stainless steel or ceramic. First and second roller guides  30 ,  35  may also be constructed from a non-magnetic material and configured to rotate at a speed substantially identical to that of the magnetic tape media  55  passing over their respective surfaces. Rotation of the roller guides  30 ,  35  in this manner reduces friction between the roller guide surfaces and the magnetic layer of the magnetic tape media  55 . In cases where the binder layer has deteriorated due to hydrolysis, the reduced friction advantageously decreases shedding of the magnetic layer. Although two tape guides  20 ,  25  and two roller guides  30 ,  35  are depicted in  FIG. 1 , it will be appreciated that in other embodiments additional tape guides and roller guides may be provided depending on, for example, the length of the tape path through the transport mechanism  5 . 
         [0014]      FIGS. 2A ,  3  and  4  illustrate top, front and side views, respectively, of the head stack mounting assembly  45  of  FIG. 1 . As shown, the head stack mounting assembly  45  includes a plate  65  or other suitable structure onto which a read head  70 , a first roller guide  75 , a second roller guide  80 , and an electromagnetic shield  85  are mounted. As discussed below in connection with  FIGS. 3 and 4 , the head stack mounting assembly  45  may be of a modular construction such the assembly  45  is removable from the transport mechanism  5 . 
         [0015]    The first and second roller guides  75 ,  80  are disposed adjacent opposite sides of the read head  70  and contact the magnetic layer of the magnetic tape media  55  such that the media  55  is guided between a read surface  73  of the read head  70  and the electromagnetic shield  85 . Importantly, the first and second roller guides  75 ,  80  are positioned such that their contact with the magnetic tape media  55  properly aligns the magnetic tape media  55  with the read surface  73  while at the same time preventing the magnetic layer of the media  55  from contacting the read surface  73 . The non-zero distance introduced between the path of the magnetic tape media  55  and the read surface  73  is indicated in  FIG. 2A  by distance “d”. The head stack mounting assembly  45  thus significantly differs from conventional headstack mounting assemblies in which the magnetic layer is made to contact the read head. Because contact between the magnetic tape media  55  and the read surface  73  of the read head  70  is prevented by suitably positioning the first and second roller guides  75 ,  80 , friction between the media  55  and the read surface  73  that is characteristic of conventional headstack assemblies is altogether eliminated. Advantageously, in cases where the binder layer of the magnetic tape media  55  has deteriorated due to hydrolysis, elimination of friction in this manner prevents shedding of the magnetic layer and clogging of the read head  70  that would otherwise result if a conventional headstack mounting assembly were to be used. 
         [0016]    The non-zero distance “d” may generally be selected to be as small as possible such that read head  70  signal output losses are minimized while at the same time generally preventing its contact with the magnetic tape media  55 . In certain embodiments, for example, the non-zero distance between the path of the magnetic tape media  55  and the read surface may be about 25.4 to 254 μm, and preferably 150 to 200 μm. The non-zero distance “d” may be such that, in certain cases, fluctuations in the tension of the magnetic tape media  55  or other conditions may cause the magnetic layer of the media  55  to occasionally contact the read surface  73 . It is expected that such contact will be infrequent and will not significantly effect the operation of the read head  70  in cases in which the media  55  is susceptible to magnetic layer shedding. 
         [0017]    According to various embodiments, the read head  70  may be fabricated from laminated layers of a mu-metal alloy, a ferric base material, or other suitable material and designed to compensate, either partially or entirely, output losses that might otherwise result from the introduction of the gap between the magnetic tape media  55  and the read surface  73 . In certain embodiments, for example, one or more parameters of the read head  70  may be selected so as to maximize its useful signal output. Such parameters may include, for example, the gap length  110  ( FIG. 5B ) of the read head  70  and the gap tip depth  115  (FIG.  5 A) of the read head  70 . In one embodiment, for example, the gap length  110  may be approximately 100 μm and the gap tip depth  115  may be approximately 127 μm. In certain embodiments, the gap tip depth  115  may be selected to be as small as possible without introducing significant resonance effects, thus maximizing the coil size (i.e., the number of coil turns) of the read head  70  and, correspondingly, the signal gain of the read head  70 . Other selectable parameters of the read head  70  may include, for example, the inductance of the read head  70  and the amount of field strength induced across the coil of the read head  70 . In one embodiment, for example, the inductance of the read head  70  may be approximately 1 H. 
         [0018]    Although the figures illustrate a stereo read head for reading two tracks, one of ordinary skill in the art will recognize that the read head  70  may generally be configured to read any number of tracks arranged in any configuration or format. Additionally, although only one read head  70  is shown in the figures, it will be appreciated that the head stack mounting assembly  45  may include multiple read heads  70  depending upon, for example, the number and arrangement of tracks contained on the magnetic tape media  55 . 
         [0019]    It will further be appreciated that the read head  70  having the necessary parameters for compensating the introduction of the gap may be custom-fabricated or fabricated by modifying an existing conventional read head. In the latter case, for example, a conventional read head may be recontoured to modify the gap depth  115  and/or other parameters as necessary. 
         [0020]    In addition or as an alternative to the selection of read head  70  parameters as described above, parameters of the transport mechanism  5 , such as the velocity of the magnetic tape media  55  relative to read head  70 , may be selected to maximize the useful signal output. 
         [0021]    In certain embodiments, the head stack mounting assembly  45  may include a preamplifier circuit (not shown) in communication with the read head  70  for suitably increasing the strength of the signal generated by the coil of the read head  70  prior to subsequent signal processing stages. In other embodiments, the preamplifier circuit may be externally located with respect to head stack mounting assembly  45  (e.g., at another location within the transport mechanism  5  or within signal processing equipment in communication with the transport mechanism  5 ). 
         [0022]    The electromagnetic shield  85  is positioned opposite the read surface  73  and adjacent the substrate layer of the magnetic tape media  55 . The electromagnetic shield  85  functions to reduce stray electromagnetic noise emitted from within and/or external to the transport mechanism  5  that might otherwise interfere with the desired operation of the read head  70 . 
         [0023]    The first and second roller guides  75 ,  80  may be constructed from a non-magnetic material and configured to rotate at a speed substantially identical that of the magnetic tape media  55  passing over their respective surfaces. As with roller guides  30 ,  35 , rotation of the roller guides  75 ,  80  in this manner reduces friction between the roller guide surfaces and the magnetic layer of the magnetic tape media  55 , thus decreasing the incidence magnetic layer shedding. Although two roller guides  75 ,  80  are depicted in  FIG. 2A , it will be appreciated that in other embodiments additional roller guides may be provided depending on, for example, the length of the tape path through the head stack mounting assembly  45 . 
         [0024]    As shown in  FIG. 1 , the head stack mounting assembly  45  may further include an azimuth adjustment screw  87  for adjusting the angle of the read head  70  relative to the direction of travel of the magnetic tape media  55 . 
         [0025]      FIG. 2B  illustrates a top view of a head stack mounting assembly  46  according to another embodiment of the present invention. The head stack mounting assembly  46  is identical to the assembly  45  of  FIG. 2A  with the exception that the first and second roller guides  75 ,  80  are replaced by a first tape guide  88  and a second tape guide  89  positioned to contact the substrate of the magnetic tape media  55  so as to maintain the gap between the media  55  and the read surface  73 . The tape guides  88 ,  89  may be stationary pins constructed of a suitably non-magnetic material, such as, for example, stainless steel or ceramic. It is expected that the first and second tape guides  88 ,  89  will impart a greater degree of stability to the magnetic tape media  55  compared to that of roller guides  70 ,  80  of the embodiment of  FIG. 2A . In the embodiment of  FIG. 2B , although raised areas on the substrate resulting from media splices may occasionally cause the media  55  to contact the read surface  73 , such contact is expected to be infrequent and will not adversely affect operation of the read head  70 . Although two tape guides  88 ,  89  are depicted in  FIG. 2B , it will be appreciated that in other embodiments additional tape guides may be provided depending on, for example, the length of the tape path through the head stack mounting assembly  46 . 
         [0026]    As shown in  FIGS. 3 and 4 , the head stack mounting assembly  45  may also include a top edge guide  90  and a bottom edge guide  95 . The guides  90 ,  95  may be positioned between the first and second roller guides  75 ,  80  and include a smooth surface for slidingly contacting the top and bottom edges, respectively, of the magnetic tape media  55 , thereby increasing the lateral stability of the magnetic tape media  55  as it traverses the head stack mounting assembly  45 . In certain embodiments, the guides  90 ,  95  may be fabricated from a ceramic or other nonmagnetic material. 
         [0027]    As further shown in  FIGS. 3 and 4 , the head stack mounting assembly  45  may include a head stack mounting connector  100 . The head stack mounting connector  100  may include, for example, a male edge connector  105  including electrical contacts  110  and configured for receipt by an oppositely-gendered receptacle (not shown) of the transport mechanism  5 . It will be appreciated that other suitable types of electrical connectors (e.g., pinned connectors) of either gender may alternatively be used for the mounting connector  100 . Electrical components of the head stack mounting assembly  45 , such as the read head  70 , may thus be suitably interfaced with electrical components (e.g., amplifiers, signal processing circuitry, etc.) of the transport mechanism  5  via the connector  100 . The connector  100  may also operate to mechanically retain the head stack mounting assembly  45  within the transport mechanism  5 . In certain embodiments and as noted above, the head stack mounting assembly  45  may be of a modular construction such that it may be “unplugged” and removed from the transport mechanism  5  for cleaning/servicing or replacement with a head stack mounting assembly of a different configuration. 
         [0028]    The examples presented herein are intended to illustrate potential and specific implementations of the present invention. It can be appreciated that the examples are intended primarily for purposes of illustration of the invention for those skilled in the art. No particular aspect or aspects of the examples is/are necessarily intended to limit the scope of the present invention. 
         [0029]    It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements. Those of ordinary skill in the art will recognize, however, that these and other elements may be desirable. However, because such elements are well known in the art and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. 
         [0030]    Any element expressed herein as a means for performing a specified function is to encompass any way of performing that function including, for example, a combination of elements that perform that function. Furthermore the invention, as defined by such means-plus-function claims, resides in the fact that the functionalities provided by the various recited means are combined and brought together in a manner as defined by the appended claims. Therefore, any means that can provide such functionalities may be considered equivalents to the means shown herein. 
         [0031]    While various embodiments of the invention have been described herein, it should be apparent that various modifications, alterations and adaptations to those embodiments may occur to persons skilled in the art with the attainment of some or all of the advantages of the present invention. For example, although the transport mechanism  5  of the exemplary embodiments presented above is based on a reel to reel configuration, it is contemplated that other embodiments may utilize other tape configurations (e.g., cassette tapes). The disclosed embodiments are therefore intended to include all such modifications, alterations and adaptations without departing from the scope and spirit of the present invention.