Patent Publication Number: US-2007102563-A1

Title: Method and apparatus for producing magnetic tape cartridge

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a method and apparatus for producing a magnetic tape cartridge, and, more particularly, to a method and apparatus for winding an electromagnetic tape on a tape reel with its side edge leaned on a base flange as desired.  
      2. Description of Related Art  
      Magnetic tapes are extensively used in magnetic tape cartridges as data backup recording medium for computers. Such a magnetic tape cartridge is known in two types, one having a single tape reel and the other having a pair of tape reels. In a general way, the magnetic tape cartridge is prepared by guiding and feeding a magnetic tape reeled out from a supply reel in a cartridge casing and winding it around a core hub of a tape reel in the cartridge casing with its side edge leaned on a base flange of the reel.  
      There has been proposed air guide devices for guiding a magnetic tape in non-contact with it such as described in, for example, Unexamined Japanese Patent Publication Nos. 2002-117598 and 2004-110953. Such an air guide device comprises a cylindrical air guide barrel having a number of air holes through which air is discharged against the magnetic tape. Either air guide means is configured to guide a magnetic tape controlling it in posture and position so as to be in parallel with an axis of the cylindrical air guide barrel in a width direction of tape and to feed the magnetic tape in the a cartridge casing so as to be in parallel with an axis of the core hub of the tape reel.  
      However, according to the study findings by the inventors of this application, it has been proved that the prior art air guide makes it hard to wind a magnetic tape around the core hub with its side edge leaned on a base flange of the reel.  
     SUMMARY OF THE INVENTION  
      It is therefore an object of the present invention to provide a method and apparatus for producing a magnetic tape cartridge in which a magnetic tape is always wound with its side edge leaned on a base reel flange.  
      The foregoing object of the present invention is accomplished by a method for producing a magnetic tape cartridge by winding a magnetic tape around a tape reel having a reel hub and reel flanges secured to the reel hub which is installed in a cartridge shell housing, which comprises the steps of feeding a magnetic tape toward the tape reel, tilting down the magnetic tape in a transverse direction of the magnetic tape while guiding the magnetic tape in non-contact with the magnetic tape within a specified guide area in a longitudinal direction of the magnetic tape by air guide means, and winding the magnetic tape on the reel hub with a downside edge of the magnetic tape leaned on a specified one of the reel flanges, namely a base flange. The air guide means blows air against the magnetic tape in a specified pressure distribution pattern in which pressure is lower on the downside edge than on an opposite side edge in the transverse direction.  
      According to the present invention, a magnetic tape is biased by air so as to be tilted down in a transverse direction while guided in non-contact with the guide means within the specified guide area in the longitudinal direction prior to being wound on the reel hub. In consequence, the magnetic tap is wound with the downside edge thereof leaned on the base flange.  
      The pressure distribution pattern is such that pressures decrease gradually in the transverse direction in proportion as getting closer to the downside edge of the magnetic tape. Further, the pressure distribution pattern is desirably such that pressures increase gradually in proportion as getting closer to extreme ends of the specified guide area in the circumferential direction.  
      Tilting down of the magnetic tape in the transverse direction is performed by means of an uneven distribution of air pressure which is provided by air guide means. Specifically, the air guide means comprises air blowing means for blowing pressurize air against the magnetic tape in a specified pressure distribution pattern in which pressure is lower on the downside edge than on an opposite side edge in the transverse direction. The air blowing means may comprise an air supply source for supplying pressurized air and a cylindrical tape guide barrel disposed in a path of the magnetic tape with a center axis put in parallel with an axis of rotation of the tape reel for forming an air chamber therein for receiving the pressurized air. The cylindrical tape guide barrel is provided with a number of air discharge orifices formed in the barrel wall through which the pressurized air introduced in the air chamber is blown against the magnetic tape in the specified pressure distribution pattern. With the air blow, the magnetic tape is paced from the cylindrical tape guide barrel and tiled down in a transverse direction of the magnetic tape. The air discharge orifices are distributed in axial and circumferential directions in various forms. For example, the air discharge orifices in the axial direction may be made smaller in diameter on a base side of the cylindrical tape guide barrel which is on the same side as the specified reel flange than at the middle of the specified guide area in the axial direction, or decrease gradually smaller in diameter as getting on toward a base side of the cylindrical tape guide barrel which is on the same side as the specified reel flange. Further, the air discharge orifices may be distributed in a distribution pattern in which a density of distribution is lower on a base side of the cylindrical tape guide barrel which is on the same side as the specified reel flange than at the middle of the specified guide area in the axial direction, or in a distribution pattern in which a density of distribution decrease gradually lower as getting on toward a base side of the cylindrical tape guide barrel which is on the same side as the specified reel flange. The air discharge orifices may further distributed in various pattern in the circumferential direction. Specifically, the air discharge orifices in the circumferential direction may be made larger in diameter on opposite extreme ends of the specified guide area in the circumferential direction than at the middle of the specified guide area in the circumferential direction, or may increase gradually larger in diameter as getting on toward an extreme end of the specified guide area. Further, the air discharge orifices may be distributed so that a density of distribution is higher on opposite extreme ends of the specified guide area in the circumferential direction than at the middle of the specified guide area, or so that a density of distribution increases gradually higher as getting on toward an extreme end of the specified guide area in the circumferential direction.  
      Although, according to the prior art air guide device in which the air discharge orifices have the same diameters and are evenly distributed in a direction of tape feed, pressures of air blowing against a magnetic tape decrease gradually in proportion as getting closer to opposite extreme ends of the overlap area between the magnetic tape and the tape guide barrel in the direction of tape feed. As a result, according to circumstances, the space between the magnetic tape and the tape guide barrel decreases gradually as getting closer to the opposite extreme ends of the overlap area, so that it is feared in such an event that the magnetic tape possibly comes in contact with the tape guide barrel near the boundaries on the base side. However, according to the present invention, the magnetic tape is kept at an almost equal distance from the tape guide barrel due to the uneven pressure distribution in the direction of tape feed while passing through the overlap area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing and other objects and features of the present invention will be clearly understood from the following detailed description when reading with reference to the accompanying drawings wherein same or similar parts or mechanisms are denoted by the same reference numerals throughout the drawings and in which:  
       FIG. 1  is a schematic view of a magnetic tape winding apparatus for implementing a method for preparing a magnetic tape cartridge according to a preferred embodiment of the present invention;  
       FIG. 2  is a perspective view of an air tape guide;  
       FIG. 3  is a perspective view of a cylindrical tape guide barrel;  
       FIG. 4  is a cross-sectional view taken along a line IV-IV of  FIG. 3 ;  
       FIG. 5  is a plan view of the cylindrical tape guide barrel;  
       FIG. 6  is a cross-sectional view taken along a line VI-VI of  FIG. 5 ;  
       FIG. 7  is a schematic sectional view showing a magnetic tape guided by the tape guide; and  
       FIG. 8  is a plan view of an alternative cylindrical tape guide barrel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to the accompanying drawings in detail, and in particular, to  FIG. 1  showing a magnetic tape winding apparatus  1  for implementing a method for preparing a magnetic tape cartridge  3  by winding a magnetic tape  2  having a given tape width around a tape reel  4  installed in a cartridge shell housing  5 , the magnetic tape winding apparatus  1  comprises a tape feeding device  10  for continuously reeling out the magnetic tape  2 , a tape winding device  20  for driving the tape reel  4  installed in the cartridge shell housing  5  at a specified speed of rotation so as to wind the magnetic tape  2  around the tape reel  4 , a polishing device  30  disposed between the tape feeding device  10  and the tape winding device  20  for polishing a surface of the magnetic tape  2 , a cleaning device  40  disposed after the polishing device  30  for cleaning both surfaces of the magnetic tape  2  and a tension controlling device  50  disposed after the cleaning device  40  for controlling tension against the magnetic tape  2 . The tape winding device  20  including a cartridge holding and positioning device  21  for holding the magnetic tape cartridge  3  in a specified position with an axis of rotation of the tape reel  4  put in a horizontal position. These devices  20 ,  30 ,  40  and  50 , which are known in various forms and may take any known forms well known in the art, are in a path of the magnetic tape  2  defined by a number of guide rollers  80 . The magnetic tape winding apparatus  1  further comprises an air guide device  90  (which will be described in detail later) disposed immediately before the tape winding device  20  for guiding the magnetic tape  2  in a non-contact manner and a tape traction device  22  for carrying a leading end of the magnetic tape  2  guided by the air guide device  90  into the cartridge shell housing  5  of the magnetic tape cartridge  3  held in the specified position by the cartridge holding and positioning device  21 . The magnetic tape winding apparatus  1  is further provided with a cartridge feed device  60  in which a number of the magnetic tape cartridges  3  are stored in piles therein and which supplies the magnetic tape cartridges  30  to the tape winding device  20  one by one, a cartridge holding and positioning device  21  for holding the magnetic tape cartridge  3  supplied from the cartridge feed device  60  in a specified position for winding of the magnetic tape  2 , and a cartridge ejecting device  70  for ejecting a completed magnetic tape cartridge  3  from the tape winding device  20 . The devices associated with feeding and winding of the magnetic tape  2  are controlled in operation by switches of an operating board  100 .  
      The tape feeding device  10  includes tape reels  11   a  and  11   b  on which the magnetic tapes  2  are wound and which are interchangeably driven at a specified rotational speed to reel out the magnetic tape  2 . While one of the tape reels  11   a  and  11   b  is out of service, another magnetic tape is prepared on it for another service. Therefore, magnetic tape  2  is continuously fed toward the tape winding device  20 . The magnetic tape  2  reeled out from the tape reel  11   a  or  11   b  is subjected to surface polish by the polishing device  30  and to removal of tape dust and foreign particles from both surface of the magnetic tape  2  by the cleaning devices  40 , and then sent to the air guide device  90 . On the way, the magnet tape  2  is appropriately tensioned by the tension controlling device  50 .  
      Referring to  FIGS. 3 and 4  showing the air guide device  90  in detail, the air guide device  90  controls the magnetic tape in posture and position in a transverse direction so as to wound it around the tape reel  4  with its side edge leaned on a base reel flange as will be described latter. As shown, the air guide device  90  comprises a cylindrical solid base pillar  110  having a frustum-shaped top end  110   a  which is removably secured in a horizontal position to a frame plate  105  of the magnetic tape winding apparatus  1 , a top retainer disk  112  and a cylindrical tape guide barrel  111  disposed between the base pillar  110  and the top retainer disk  112 . The cylindrical tape guide barrel  111  is borne down on the frustum-shaped top  110   a  of the base pillar  110  by screwing up top retainer disk  112  against the top retainer disk  112  by a tap bolt  113  passing through a center hole  112   c  of the top retainer disk  112  and fastened in a center screw bore  110   d  of the base pillar  110 . More specifically, as clearly shown in  FIG. 4 , a top end of the frustum-shaped top  110   a  of the base pillar  110  is surrounded by an annular shoulder  110   b . Similarly, the top retainer disk  112  has a reversed frustum-shaped under side wall  112  whose bottom end is surrounded by an annular shoulder  112   b . Both shoulders  111   b  and  112   b  have the same outer diameters as an inner diameter of the tape guide barrel  111  so as to be snugly fitted by the tape guide barrel  111 . The base pillar  110  has an air conduit bore  110   c  extending from the bottom to the top and opening to the top end of the frustum-shaped top  110   a . The air conduit bore  110   c  is connected to an air pipe  105   b  through a joint bore  105   a  formed in the frame plate  105 . Pressurized air is supplied by an air pump (not shown) into an air chamber  111   c  formed by the tape guide barrel  111  between the frustum-shaped top end  110   a  of the base pillar  110  and the top retainer disk  112 . The tape guide barrel  111  has a number of air discharge orifices  111   b  formed on a grid through which pressured air introduced into the air chamber  111   c  is discharged  
      Referring to  FIGS. 5 and 6 , the air guide device  90  guides the magnetic tape  2  traveling toward the tape reel  4  in the cartridge shell housing  5  in a direction of tape feed indicated by an arrow C. As was described previously, both the air guide device  90  and tape reel  4  are put in the horizontal position with their axes in parallel with each other. The tape reel  4  comprises a core hub  4   a  and reel flanges  4   b  and  4   c  secured to opposite ends of the core hub  4   a . Either one of the reel flanges  4   b  and  4   c , namely the reel flanges  4   b  in this embodiment, is used as a base reel flange on which side edges of convolutions of the magnetic tape  2  wound around on the core hub  4   a  lean so as thereby to be flush with one another. The air discharge orifices  111   b  are all less than 0.2 mm in diameter and formed in a predetermined pattern. In this embodiment, the air discharge orifices  111   b  are formed at grid points so as to line up in three circumferential rows and in six axial rows. The air discharge orifices  111   b  in each axial row are different in diameter, specifically, the closer the discharge orifice  111   b  gets on toward a base side  111   d  of the tape guide barrel  111  which is on the same side as the base reel flange  4   b , the smaller the diameter decrease. That is, the air discharge orifice  111   b  on the base side  111   d  of the tape guide barrel  111  is smallest in diameter among the three, and the air discharge orifice  111   b  on the side opposite to the base side  111   d  of the tape guide barrel  111  is largest in diameter among the three. Further, the air discharge orifices  111   b  in each circumferential row are different in diameter, specifically, the closer the discharge orifice  111   b  gets on toward the middle of the circumferential row, the smaller the diameters decrease. That is, the air discharge orifice  111   b  at the middle of the circumferential row is smallest among the six, and the air discharge orifices  111   b  at opposite ends of the circumferential row are largest among the six. The circumferential rows of air discharge orifices  111   b  are formed within a specified extent sufficiently cover an overlap angle θ over which the magnetic tape  2  overlaps the tape guide barrel  111  in the circumferential direction as clearly shown in  FIG. 6 .  
      Air introduced into the air chamber  111   c  of the tape guide barrel  111  blasts out through the air discharge orifices  111   b  to blow against the magnetic tape  2  traveling over the tape guide barrel  111  so as thereby to space the magnetic tape  2  from the tape guide barrel  111  traveling toward the tape winding device  20 . In other words, the magnetic tape  2  is guided by the air guide device  90  so as to travel over the same in non-contact with the tape guide barrel  111 . At this time, pressures of the air blowing against the magnetic tape  2  gradually increase in proportion as getting away further from the base side  111   d  of the tape guide barrel  111 , so that the magnetic tape  2  is tilted down on the base side  111   d  of the tape guide barrel  111  as shown in  FIG. 7   
      The tape winding device  20  includes the cartridge holding and positioning device  21  for holding the magnetic tape cartridge  3  supplied from the cartridge feed device  60  in a specified position with an axis of rotation of the tape reel  4  put in a horizontal position and the tape traction device  22  for carrying a leading end of the magnetic tape  2  into the cartridge shell housing  5  of the magnetic tape cartridge  3  held in position by the cartridge holding and positioning device  21 . The tape traction device  22  is operated by, for example, a pneumatic drive system to move between a standby position outside the cartridge holding and positioning device  21  and a working position in the cartridge holding and positioning device  21 . The tape traction device  22  is provided with suction holding means (not shown) for holding a leading end of the magnetic tape  2  in the standby position and presses it against the reel hub  4   a  of the tape reel  4  in the working position.  
      In operation of the magnetic tape winding apparatus  1 , when the magnetic tape winding apparatus  1  is activated, either one of the tape reels  11   a  and  11   b  is driven to reel out the magnetic tape  2  at a specified rate. The magnetic tape  2  from the tape reel  11   a  or  11   b  is guided in the path by the guide rollers  80  toward the tape traction device  22 . During traveling to the tape traction device  22 , the magnetic tape  2  is polished by the polishing device  30  and cleaned by the cleaning devices  40 . The magnetic tape  2  is controlled by the tension controlling device  50  so as to travel under proper tension. Until the magnetic tape  2  reaches the tape traction device  22 , the air pump for supplying air to the air guide device  90  is under suspension Therefore, the magnetic tape  2  travels forward being guided between inclined wall surfaces of the frustum-shaped top end  110   a  of the cylindrical solid base pillar  110  and the frustum-shaped under side wall  112  of the top retainer disk  112 . When the tape traction device  22  in the standby position is reached by the leading end of the magnetic tape  2 , while the tape traction device  22  is activated to hold the magnetic tape  2  by suction, the tape winding device  20  is activated to rotate the tape reel  4  of the magnetic tape cartridge  3  held in position by the cartridge holding and positioning device  21  at a specified speed of rotation. The magnetic tape winding apparatus  1  is adapted to control the tape reels  11   a ,  11   b  and  4  so that a reel out rate of the tape reel  11   a  or  11   b  and a winding rate of the tape reel  4  match well with each other. Once the tape traction device  22  moves to the working position and presses the magnetic tape  2  against the reel hub  4   a  of the tape reel  4  which is rotating a the specified speed of rotation, the tape traction device  22  is deactivated and return to the standby position. At the same time, the magnetic tape  2  is wound around the reel hub  4   a . When the magnetic tape  2  is wound around the reel hub  4   a  at least one or two turns, the magnetic tape  2  encounters a momentary increase in tension. The magnetic tape winding apparatus  1  detects the momentary increase in tension to activate the air pump of the air guide device  90 , more specifically the air pump of the air guide device  90 , and controls rotation of the tape reels  4  and  11   a  or  11   b  so as to balance the reel out rate and the winding rate. Once the magnetic tape  2  coils around the reel hub  2 , the air pump of the air guide device  90  is activated to supply pressurized air into the air chamber  111   c . In consequence, the air blasts out through the air discharge orifices  111   b  of the tape guide barrel  111  to blow against the magnetic tape  2  and spaces it from the tape guide barrel  111 . That is, the magnetic tape  2  is tilted down in a transverse direction. In this way, while traveling forward to the tape reel  4 , the magnetic tape  2  is always biased toward the base side  111   d  of the tape guide barrel  111  and, in natural consequence, against the base flange  4   b  of the tape reel  4  as shown in  FIG. 7 . Thereafter, the magnetic tape  2  is continuously wound around the reel hub  4   a  of the tape reel  4  with its side edge biased and, in consequence, leaned on the base flange  4   b.    
       FIG. 8  shows an alternative of the air discharge orifice distribution pattern. In this air discharge orifice distribution pattern, all of air discharge orifices  111   b  are identical dimensionally and are distributed so as to increase distribution density as getting far away from the base side  111   d  of the tape guide barrel  111  and as getting on toward opposite extreme ends of the overlap area in the direction of tape feed C. This air discharge orifice distribution pattern shown in  FIG. 8  brings about the same effect of pressure distribution as the air discharge orifice distribution pattern shown in  FIG. 7 .  
      In the case where the air discharge orifices  111   b  have the same diameters and are evenly distributed in the direction of tape feed C, pressures of air blowing against the magnetic tape  2  gradually increase in proportion as getting closer to the opposite extreme ends of the overlap area between the magnetic tape  2  and the tape guide barrel  111  in the direction of tape feed C. As a result, the space between the magnetic tape  2  and the tape guide barrel  111  gradually decreases as getting closer to the opposite extreme ends of the overlap area, so that it is feared that the magnetic tape  2  at the side edge possibly comes in contact with the tape guide barrel  111  near the boundaries on the base side. However, with the air guide device  90 , the magnetic tape  2  is kept at an almost equal distance from the tape guide barrel  111  due to the uneven pressure distribution in the direction of tape feed C while passing through the overlap area. Nevertheless, it is not always essential to distribute the air discharge orifice  111   b  so as to increase pressures higher as getting on toward opposite extreme ends of the overlap area in the direction of tape feed C.  
      It is a matter of course that variants of air discharge orifice distribution pattern which brings about the same effect of pressure distribution as those described above may occur to those skilled in the art  
      It is also to be understood that although the present invention has been described with regard to preferred embodiments thereof, various other embodiments and variants may occur to those skilled in the art, which are within the scope and spirit of the invention, and such other embodiments and variants are intended to be covered by the following claims.