Abstract:
A sewing machine which may employ a loop-making hook rotating about a vertical axis employs a one-way bobbin and bobbin case. A bobbin can have a larger flange and a smaller flange so as to fit in a suitably configured bobbin case in only one way. The bobbin may have a blind axial opening with a guide groove to fit a winder spindle in only one way so that the bobbin can only be wound in one way. Attempts at incorrect orientations cause the bobbin to protrude from the bobbin case in an obviously incorrect manner. Inadvertent efforts to wind the bobbin incorrectly are likely to be fruitless. Thus, a user can readily install the bobbin in the bobbin case with a proper orientation and with the thread correctly wound. Surprisingly, stitching problems, such as poor seams or the like, can be reduced.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0001]     (Not applicable.)  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a sewing machine, a bobbin to supply thread in the sewing machine, a bobbin case for the bobbin and a method of winding thread on the bobbin. The invention relates particularly, but not exclusively, to sewing machines intended for domestic or household use, and can be applied to industrial and other sewing machines, if desired. In general, the invention provides a novel and improved bobbin, bobbin case and bobbin winding method useful with sewing machines employing a loop-making hook rotating about a vertical axis, and other types of sewing machine.  
       BACKGROUND OF THE INVENTION  
       [0003]     Sewing machines which employ an upper and lower thread to form a seam or other sewn element employing lockstitches or other suitable stitches are sometimes subject to stitching problems which yield poor seams or other stitchwork.  
         [0004]     Beitzel U.S. Pat. No. 699,067 discloses a sewing machine of this type which employs a spool of thread supported in spool house mounted for rotation beneath a work bed to supply a lower thread to the needle.  
         [0005]     Johnson U.S. Pat. No. 4,182,  250  and Rodda et al. U.S. Pat. No. 4,487,142 both disclose sewing machine employing a rotating hook which functions as a loop taker. As disclosed in these patents a bobbin case, bearing a bobbin wound with thread, can be located beneath the sewing machine work bed, directly under the needle which is threaded with the upper thread. A hook travels around the bobbin case, rotating about a vertical axis, takes a loop from the upper thread and pulls it around the bobbin. The loop extends around the lower thread which runs from the bobbin to the fabric. As it advances, the hook sheds the loop and the sewing machine&#39;s take-up lever tightens the threads into a lockstitch or the like.  
         [0006]     The above patents do not address the problem of poor stitch formation which may occur in a lockstitch or similar sewing machine which draws a lower thread from a bobbin contained in a bobbin case.  
         [0007]     The foregoing description of background art may include insights, discoveries, understandings or disclosures, or associations together of disclosures, that were not known to the relevant art prior to the present invention but which were provided by the invention. Some such contributions of the invention may have been specifically pointed out herein, whereas other such contributions of the invention will be apparent from their context. Merely because a document may have been cited here, no admission is made that the field of the document, which may be quite different from that of the invention, is analogous to the field or fields of the present invention.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an object of the invention to provide a sewing machine which addresses the problem of poor stitch formation which may occur in forming lockstitches or the like when drawing a lower thread from a bobbin contained in a bobbin case. Other objects of the invention lie in providing a bobbin, bobbin case and threading method useful in addressing this problem.  
         [0009]     In one aspect, the invention provides a sewing machine which includes a needle mounted for reciprocal movement in opposed descending and ascending directions toward and away from a workpiece to sew the workpiece with an upper thread. In addition the machine includes a bobbin mounted to supply a lower thread to the needle. The bobbin can comprise a hub to support wound thread and respective first and second flanges located at opposed ends of the hub to retain the thread on the hub. Furthermore, the machine includes a bobbin case to support the bobbin for reciprocal movement beneath the workpiece, the bobbin case having a chamber to receive and seat the bobbin. In this novel sewing machine the bobbin and bobbin case are cooperably configured to seat the bobbin in the bobbin case chamber in a working orientation and to prevent seating of the bobbin in a nonworking orientation.  
         [0010]     To this end, the second bobbin flange can be larger than the first bobbin flange. The bobbin case chamber can have a mouth and a narrower portion inwardly of the chamber mouth. The mouth can be capable of receiving the second bobbin flange and the narrower portion can be capable of receiving the smaller, first bobbin flange. This structure enables proper seating of the bobbin in the bobbin case chamber, but the narrower portion of the chamber is incapable of receiving the larger, second bobbin flange being thereby preventing seating of the bobbin in a nonworking orientation.  
         [0011]     The bobbin hub can have an axial opening to receive a bobbin winder spindle in one axial direction. The hub opening may be at least partially obstructed to prevent insertion of the bobbin winder spindle into the hub opening in another axial direction opposed to the one axial direction. Embodiments of bobbin employing this construction fit the winder spindle in only one way. Employing a predetermined winder direction, incorrect winding can be avoided.  
         [0012]     Surprisingly, it has been found that some stitching problems in lockstitch sewing machines employing a lower thread drawn from a bobbin mounted in a bobbin case are attributable to user error in replacing and/or rewinding empty bobbins. The invention provides structural measures useful in overcoming or mitigating these problems.  
         [0013]     In another aspect, the invention provides a bobbin to supply thread in a sewing machine. The sewing machine can comprise a needle to sew the workpiece with an upper thread and a lower thread, the needle being mounted for reciprocal movement in opposed descending and ascending directions toward and away from the workpiece. The sewing machine can comprise a bobbin case to support the bobbin for reciprocal movement beneath the workpiece. The bobbin case can have a chamber to receive and seat the bobbin. The bobbin may comprise a hub to support wound thread and respective first and second flanges located at opposed ends of the hub to retain the thread on the hub. The bobbin and bobbin case can be cooperably configured to seat the bobbin in the bobbin case chamber in a working orientation and to prevent seating of the bobbin in a nonworking orientation.  
         [0014]     The invention also provides a bobbin case having the described cooperative structure and provides such a bobbin case with the bobbin seated therein.  
         [0015]     In a further aspect, the invention provides a method of winding thread on the bobbin of such a sewing machine which comprises a number of steps. The steps may comprise assembling the bobbin, when in need of thread, to the bobbin winder spindle by inserting the bobbin winder spindle into the bobbin hub in the one axial direction. Thread can then be wound on to the bobbin mounted on the bobbin winder spindle. In the event of an attempt to insert the bobbin winder spindle into the hub opening in the opposed axial direction, the method includes removing and reorienting the bobbin when the partial obstruction prevents the insertion attempt. Pursuant to the method, after removing and reorienting the incorrectly oriented bobbin, the bobbin winder spindle is now inserted into the bobbin and the bobbin is wound with thread. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0016]     Some embodiments of the invention, and of making and using the invention, as well as the best mode contemplated of carrying out the invention, are described in detail below, by way of example, with reference to the accompanying drawings, in which like reference characters designate like elements throughout the several views, and in which:  
         [0017]      FIG. 1  is a front perspective view showing one embodiment of an error-resistant bobbin for a sewing machine, according to the invention;  
         [0018]      FIG. 2  is a front perspective view of a top portion of a sewing machine showing an embodiment of bobbin winder mechanism for winding the bobbin illustrated in  FIG. 1  wherein the bobbin is mounted on a winder spindle;  
         [0019]      FIG. 3  is a view similar to  FIG. 2  showing the bobbin detached from the winder spindle and having a desired orientation;  
         [0020]      FIG. 4   a  is a view similar to  FIG. 3 , showing a portion of the structure shown in  FIG. 3  wherein the bobbin has an undesired orientation;  
         [0021]      FIG. 4   b  is a view similar to  FIG. 4   a,  from a different angle, wherein the bobbin has the undesired orientation shown in  FIG. 4   a;    
         [0022]      FIG. 5  is a front perspective view of the top portion of a sewing machine similar to that shown in  FIG. 2 , showing one embodiment of a bobbin winding method according to the invention;  
         [0023]      FIG. 6  is a cross-sectional view of one embodiment of an error-resistant bobbin case according to the invention, within which the bobbin illustrated in  FIG. 1  is accommodated with a desired orientation;  
         [0024]      FIG. 7  is a cross-sectional view of a rotating hook mechanism employing a bobbin case such as that shown in  FIG. 6  in which a bobbin like that illustrated in  FIG. 1  has been properly installed;  
         [0025]      FIG. 7   a  is a view of the bobbin case shown in  FIG. 6 , with a bobbin, such as that illustrated in  FIG. 1 , properly installed;  
         [0026]      FIG. 8  is a top perspective view of the work bed of a sewing machine employing the rotating hook mechanism shown in  FIG. 7 , with a cover retracted to reveal the bobbin and bobbin case;  
         [0027]      FIG. 9  is a view similar to  FIG. 7  showing an attempt to improperly install the bobbin in the bobbin case shown in  FIG. 6 ; and  
         [0028]      FIG. 9   a  is a view similar to  FIG. 7   a  also showing an attempt to improperly install the bobbin in the bobbin case. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     It is an understanding of the invention that lockstitch or similar sewing machine which draw a lower thread from a bobbin contained in a bobbin case are likely to consume a large amount of the lower thread. This circumstance requires frequent manually effected replacements of the lower thread bobbin. Typically, to do this, the operator or user must stop the sewing machine, remove the bobbin from the bobbin case and rewind the bobbin with new thread. The rewound bobbin must then be reinstalled in the bobbin case.  
         [0030]     While removal and reinstallation of the bobbin may be a necessary procedure and may often be straightforward it is nevertheless a manual procedure which with known machines may be subject to one or more errors. It is an insight of this invention that such errors may lead to stitching problems and poor seams or other poor stitchwork.  
         [0031]     The invention provides a novel, error-resistant bobbin useful for supplying thread to the needle of a sewing machine. It also provides a novel bobbin case which is cooperative with the bobbin.  
         [0032]     In particular, but not exclusively, the novel bobbin is useful with sewing machines of the type comprising a needle mounted for reciprocal movement in opposed descending and ascending directions. Typically, in such machines, the needle is carried by a needle bar which moves toward and away from a workpiece to sew the workpiece, which may for example be one or more layers of fabric, with an upper thread threaded through the needle. For certain stitches, for example straight stitches and zig-zag stitches, a second lower thread may be supplied to the needle from beneath a work bed which supports the fabric. The novel bobbin can be used to supply this lower thread, for which purpose it may be mounted beneath the work bed.  
         [0033]     When the bobbin runs out of thread, it has to be rewound. This may be accomplished by manually removing the bobbin from the bobbin case and mounting it on a winder spindle on top of the sewing machine where it is rewound with thread from a stock source such as a spool or reel of thread using a rotary drive supplied by the sewing machine. While the bobbin winding process is essentially simple, known methods are prone to certain errors. For example, the bobbin may be wound upside down or in the wrong direction or may be inserted into the bobbin case the wrong way round. Also, the winding operation may in some cases become uncontrolled, tangling knotting or even breaking the thread as a result of improper mounting of the bobbin on the winder spindle, or other factors. The bobbin and bobbin case and associated bobbin winder mechanism illustrated in the drawings can alleviate one or more of these problems.  
         [0034]     The sewing machine can be a domestic sewing machine useful for sewing in a household or other domestic environment or other suitable location. However, the inventive bobbin may be employed with other sewing machines as will be apparent to those skilled in the art. Only portions of the complete sewing machine are shown. The structure not shown can take any suitable form, as is well known in the art and may for example comprise a portable unit or a table-mounted unit. While it is envisaged that the invention is particularly useful when embodied in a unit supported or mounted on a tabletop, bench or the like for operation by a seated user, it will be understood that the invention can be embodied in other sewing machines, as will be or may become apparent. Directional references such as “front”, “rear” or “behind”, “up”, “down”, “left” and “right”, as used herein are to be understood as being from the perspective of such a user  
         [0035]     As shown in  FIG. 1 , a sewing machine bobbin  10  can comprise a hollow, approximately cylindrical, central hub  12  to support wound thread (not shown in this figure) which hub is with its axis vertically disposed in  FIG. 1 . Bobbin  10  can have a first flange  14  at one end of central hub  12  and a second flange  16  located at the other end of central hub  12 , opposing flange  14 , to retain the thread on the hub  12 . As oriented in  FIG. 1 , bobbin flanges  14  and  16  can be described as lower and upper flanges respectively. In the embodiment shown, they are disposed perpendicularly to the axis of central hub  12 .  
         [0036]     To help control user errors in handling bobbin  10 , as will be further explained herein, second flange  16  is distinctly larger in diameter than flange  14 . Flange  16  can, for example, be from about 2 to about 10 percent larger in diameter than flange  14 , although other proportions may be employed. As shown in  FIG. 1 , flanges  14  and  16  are uniformly thin disks with circular peripheries which are formed integrally and monolithically with central hub  12 , for example as a one-piece molding. However, other shapes and configurations may be employed including, for example, a polygonal shape and a tapered cross-section in a radial plane. Also, while shown as being similar, one flange  14  or  16  may have a different geometry from the other. One or more intermediate flanges (not shown) could be provided, if desired, between flanges  14  and  16 , for example to permit bobbin  10  to carry multiple threads. Such intermediate flanges, if provided, desirably are smaller than flange  16 .  
         [0037]     The peripheries of flanges  14  and  16 , in the circular embodiment shown in  FIG. 1 , lie on a conical or frusto-conical surface.  
         [0038]     Central hub  12  has an axial opening  18  to receive a bobbin winder spindle  30  ( FIG. 2 ) in one axial direction. In the embodiment shown, central hub  12  is thin walled and hub opening  18  is a sizeable volume occupying much of the volume of central hub  12 . Hub opening  18  is at least partially obstructed to prevent insertion of the bobbin winder spindle  30  into central hub  12  opening in the opposite axial direction so that bobbin  10  is a one-way fit on the winder spindle  30  and can only be assembled with the spindle in a properly oriented fashion. In the embodiment shown in  FIG. 1 , hub opening  18  is obstructed by the second bobbin flange which extends continuously across the whole cross-section of hub opening  18  to close it. Other obstructions may be employed to provide bobbin  10  with a desirable one-way character, for example a constricted diameter to hub opening  18  at second flange  16 , a cross-member extending across hub opening  18  at or near second flange  16  or a tapering of hub opening  18  (and thence of the bobbin winder spindle  30 ) towards second flange  16 .  
         [0039]     Hub opening  18  is formed with a channel-like keyway  20 , which may be a groove or slot and which extends axially along part of hub opening  18 , and opens at one end into smaller, first flange  14 . The other end of keyway  20  is blind. Other suitable keying, or spindle-cooperative locking structure, will be apparent to those skilled in the art. Second bobbin flange  16  has a threading aperture  22  adjacent central hub  12  for receiving the end of a thread to be wound on bobbin  10 .  
         [0040]     An optional strengthening fillet  24  can be provided around the junction between second flange  16  and central hub  12  and also around the junction between first flange  14  and central hub  12 , which latter fillet is not shown.  
         [0041]     Bobbin  10  can be constructed in one monolithic piece, as noted above, or may be fabricated from multiple components welded, adhered, fastened with fasteners or otherwise assembled together. In one embodiment of the invention, bobbin  10  is molded from a durable, and optionally resilient, material, for example a suitable thermosetting synthetic polymeric resin, such as clear styrene acrylonitrile copolymer.  
         [0042]     Bobbin  10  can have any suitable size and may for example be of a size suitable to accommodate from about 5 to about 100 meters of wound cotton thread of a type commonly used for domestic sewing such as 100% mercerized cotton thread N o 50. One embodiment of the invention provides a bobbin  10  with a capacity for from about 25 to about 38 meters of such cotton thread. Such a bobbin could have dimensions of, for example, about 20 mm external diameter, 10 mm height and a central hub diameter of about 8.0 mm. Other bobbins may be in proportion or may have other suitable dimensions, as will be apparent to one skilled in the art.  
         [0043]     Bobbin  10  can have any desired appearance and finish and may for example be transparent or opaque, colored or achromatic. In one embodiment of the invention, bobbin  10  is supplied in a range of transparent colors including pastel blues, greens pinks, yellows, secondary colors and stronger tints of the pastel hues.  
         [0044]     Referring now to  FIGS. 2-3  and  5 , a bobbin winder mechanism  26  can be located on the top or back of a sewing machine  28 , of which only a portion is shown in the drawings, or elsewhere on or off the sewing machine, as may be desired. It will be understood that those parts of the sewing machine that are neither illustrated nor described may have any suitable structure known or apparent to one skilled in the art in light of this disclosure, or as will become known or apparent as the art develops.  
         [0045]     The bobbin winder mechanism comprises a bobbin winder spindle  30  projecting upwardly from the top of sewing machine  28  and which can be rotatably driven by sewing machine  28 . Winder spindle  30  is receivable into hub opening  18 . Winder spindle  30  and hub opening  18  have cooperative locking structure, in the vicinity of first bobbin flange  14 , to lock bobbin  10  to the winder spindle  30  against rotation of bobbin  10  relatively to the winder spindle  30 . As may be seen from  FIG. 1 , in the embodiment shown, the other end of bobbin  10 , in the vicinity of second flange  16 , lacks locking structure cooperative with the winder spindle  30 .  
         [0046]     Winder spindle  30  can be resiliently engageable in central hub opening  18  to grip central hub  12  for rotation therewith. Winder spindle  30  may be a close sliding fit in hub opening  18 . In one embodiment of the invention, the winder spindle  30  is formed of a resilient material, has a transverse dimension nominally larger than axial opening  18  and is resiliently compressible laterally to receivable in central hub  12  opening. Such compressibility can be provided by a transverse slot  32  opening at the free end  34  of winder spindle  30 . With this construction, winder spindle  30  has a diameter at its free end which is slightly larger than that of hub opening  18 . Free end  34  may be chamfered or otherwise shaped to guide it into hub opening  18 .  
         [0047]     The locking structure can comprise a key  36  rotatable with winder spindle  30  and which is configured to be accommodated in keyway  20 . Key  36  may be formed as an axial rib projecting from winder spindle  30 , or may have other suitable structure.  
         [0048]     Winder spindle  30  may be fabricated of any suitable material, for example a durable resilient plastic such as an acetal copolymer for example that supplied under the trademark HOSTAFORM® LW90 BSX (Hoechst A.G.).  
         [0049]     Multiple stops  38  can be disposed peripherally around the winder spindle  30  to position central hub  12  along the winder spindle  30 . In the embodiment illustrated, stops  38  have the form of longitudinal splines projecting radially from winder spindle  30 . The upper end of each stop  38  provides a seat to support bobbin  10  during winding. Together, stops  38  provide a ring of support for bobbin  10  around winder spindle  30 .  
         [0050]     Winder spindle  30  can be freely rotatable about its vertical axis with a resistance and/or inertia which can be predetermined to facilitate a smooth winding operation. Winder spindle  30  is shown in the drawings in a drive-engaging position where it receives rotary drive from sewing machine  28 . In the particular embodiment shown, rotary drive for bobbin  10  is provided by a drive boss  40  which receives rotational drive from sewing machine  28 .  
         [0051]     Drive boss  40  provides drive to bobbin  10 , when seated on winder spindle  30 , by frictional engagement therewith. For this purpose, drive boss  40  has a cylindrical shape with a cylindrical outer surface  42 , a flat or domed top surface  44  and a peripheral recess  46  around the upper circumference edge of drive boss  40 . Drive boss  40  is mounted on a drive shaft  48  which is drivingly connected, or connectable, with the sewing machine drive (not shown). Drive shaft  48  extends through an aperture  50  in the top housing of sewing machine  28 . Drive boss  40  may have either a solid or hollow structure and outer surface  42  usefully has a matt or textured finish to help provide good driving engagement with flanges  14  and  16  of bobbin  10 . If desired, transmission of drive to drive boss  40  may be controlled by a user actuated control means such as a switch (not shown).  
         [0052]     Outer surface  42  of drive boss  40  can radially engage the periphery of smaller, lower flange  14  of bobbin  10  when bobbin  10  is located in its drive-engaging position, to apply drive thereto. Also, in another useful but not essential feature of the invention, when bobbin  10  is properly seated on winder spindle  30  against stops  38 , larger, upper flange  16  of bobbin  10  engages in peripheral recess  46 . Such engagement of flange  16  in recess  46  assists in the transmission of drive to bobbin  10  and in maintaining alignment of bobbin  10  on winder spindle  30  during winding. The axial position of one or more stops  38  along winder spindle  30  may be adjusted to facilitate snug engagement of bobbin flange  16  in recess  46  in drive boss  40 .  
         [0053]     In many embodiments, but not all, it is desirable to provide the user the ability to move winder spindle  30  away from drive boss  40  to disengage bobbin  10  from drive boss  40  to facilitate mounting of bobbin  10  on winder spindle  30  and removal of the loaded bobbin. Desirably, such movement of winder spindle  30  can be effected by operation of a lever or dial or other mechanical device or by electronic or electrical means (not shown). For example, winder spindle  30  can be supported for arcuate lateral movement of its rotation axis toward and away from the drive position by means not shown. If desired, winder spindle  30  may latch into its out-of-engagement position. Furthermore, a drive switch or other drive engagement device (neither one is shown) can, if desired, be associated with the movement of bobbin winder spindle  30  to turn on the rotary drive to bobbin  10  as winder spindle  30  moves toward bobbin  10  and to disconnect or turn off the drive as winder spindle  30  moves away.  
         [0054]     Also, if desired, winder spindle  30  can be resiliently urged into its drive position thereby applying a resilient urging force to engage bobbin  10  with drive boss  40 . Such resilient urging engagement can promote consistent application of a drive force to bobbin  10  and reliable winding of thread on to bobbin  10 . Sewing machine  28  can have an arcuate slot  52  formed in its housing to accommodate this lateral movement.  
         [0055]     Other suitable drive means for applying a rotational drive to bobbin  10  will be apparent to one skilled in the art. For example winder spindle  30  may be rotated by sewing machine  28  and apply to bobbin  10 . In this case, drive boss  40  can be replaced by an idler or a fixed guide that helps to guide and position bobbin  10  on winder spindle  30  but does not apply drive to it. Usefully, the drive means can be user-actuatable enabling the user to rotate or cease rotation of bobbin  10 .  
         [0056]     As shown in  FIG. 5 , a spool  54  loaded with thread can be mounted for rotation on a spool pin  56  to provide a source of supply of thread to bobbin  10 . Desirably spool pin  56  can provide limited resistance to rotation of the bobbin, to avoid overrun. A spool holder  58  can be used to retain bobbin  10  in position on spool pin  56 . Spool pin  56  can be disposed on sewing machine  28  conveniently adjacent winder spindle  30  and with any suitable orientation, for example with the longitudinal axis of spool pin  56  disposed approximately horizontally, or in another suitable location and orientation.  
         [0057]     To control the running thread  60  traveling from spool  54  to bobbin  10 , a thread guide  62  can be provided. Thread guide  62  can be spaced longitudinally away from spool pin  56 , along the top of sewing machine  28 , to receive thread  60  from spool  54  across spool holder  58  which guides thread leaving spool  54 . A winder pretensioner  64  can be disposed just downstream of thread guide  62  about which thread  60  turns into the final leg of its travel to bobbin  10 . This arrangement is intended to permit bobbin  10  to draw thread from spool  54  and to wind the thread neatly in continuous helical layers. Use of an appropriate pretensioner and one or more guides facilitates winding of bobbin  10  with a proper tension. Excess tension may lead to thread breakage, and undue slackness may cause surpluses, entanglement or knotting.  
         [0058]     In using the bobbin winder apparatus of the invention, before mounting a bobbin  10  on winder spindle  30 , the user ensures that a spool  54  of suitable thread is loaded on to spool pin  56 . The thread end is drawn from spool pin  56 , threaded over spool pin holder  58  and thread guide  62 , around pretensioner  64  to bobbin  10 . The thread end can be fed through threading aperture  22  and bobbin  10  can be given a turn or two to secure the thread end on bobbin  10  or it may be secured in another suitable manner.  
         [0059]     The user then mounts bobbin  10  on bobbin winder spindle  30 . The contrasting appearances provided by first flange  14  at one end of bobbin  10  with the large central aperture provided by hub opening  18  and the continuous surface of flange  16  which closes the other end of bobbin  10  makes it easy for the user to orient bobbin  10  correctly, with smaller flange  14  downward. With this orientation, bobbin  10  is pressed on to winder spindle  30 , compressing slotted end  34  of winder spindle  30  to fit within hub opening  18 . Winder spindle  30  can offer moderate resistance to the descent of bobbin  10 , providing a good tight feel to the user. Bobbin  10  is pushed down winder spindle  30  until it is securely seated on stops  38 . The combination of the resilient resistance provided by slotted spindle end  34  and the ability to positively seat the bobbin against stops  38 , will help most users position bobbin  10  on winder spindle  30  to be properly aligned with drive boss  40  for driving engagement therewith.  
         [0060]     In the event the user attempts to mount bobbin  10  on winder spindle  30  with larger flange  16  lowermost, such effort is rendered obviously impossible by engagement of the aperture-free flange with free end  34  of winder spindle  30 . This difficulty is graphically illustrated in  FIGS. 4   a  and  4   b.  Accordingly, the user may be expected to quickly abort the attempt and to correctly reorient bobbin  10  with flange  14  downward and hub opening  18  addressing winder spindle  30 .  
         [0061]     The foregoing operations desirably are performed with winder spindle  30  latched into its out-of-drive position. Once bobbin  10 , with thread end attached, is properly mounted on winder spindle  30 , the user can operate the appropriate control device to move winder spindle  30  into its driven position. This movement can bring bobbin  10  into engagement with winder boss  40  and may activate the drive to winder boss  40 , if the drive is so switched. Smaller flange  14  of bobbin  10  is resiliently urged into engagement with outer surface of drive boss  40  and large flange  16  engages in peripheral recess  46 .  
         [0062]     Bobbin  10  is rotated by engagement with drive boss  40 , drawing thread from spool  54  and winding bobbin  10 . The cooperative locking action of key  36  on winder spindle  30  and keyway  20  in hub opening  10  of bobbin  10  ensures that there is no rotational slippage of bobbin  10  on winder spindle  30 ; which helps promote a smooth and effective winding action. The direction of winding is predetermined by the direction of rotation of drive boss  40  and the one way orientation of bobbin  10 . It is not subject to user selection; which avoids possible error in the direction of winding that could be problematic when the wound bobbin is utilized in the bobbin case.  
         [0063]     When bobbin  10  is adequately wound, or at another desired moment, the user can activate the winder spindle drive control to terminate the rotation of bobbin  10 , cut the thread and remove the wound bobbin from winder spindle  30 . Wound bobbin  10  is now ready for loading into a bobbin case to supply thread to a sewing machine needle. An example of one suitable bobbin case and related mechanism that may be employed will now be described. Others will be apparent to those skilled in the art.  
         [0064]     One bobbin case with which bobbin  10  is useful is a bobbin case such as is employed in a rotating hook sewing machine. In one known form of rotating hook machine, the bobbin case, bearing the bobbin is located beneath the sewing machine work bed, directly under the needle which is threaded with the upper thread. A hook travels around the bobbin case, rotating about a vertical axis, takes a loop from the upper thread and pulls it around the bobbin. The loop extends around the lower thread which runs from the bobbin to the fabric. As it advances, the hook sheds the loop and the sewing machine&#39;s take-up lever tightens the threads into a stitch.  
         [0065]     One form of rotating hook machine employing a bobbin case is disclosed in Rodda et al., U.S. Pat. No. 4,487,142 cited above. The hook rotating structure constituted by rotary loop taker  20  in Rodda et al., and its associated structure, which carries bobbin case  42  in Rodda et al., can be employed to support the novel bobbin case of the present invention for rotary movement beneath a sewing machine needle. The so-supported bobbin case of the invention can be employed to supply a lower thread to the needle for forming dual-thread stitches, for example lock stitches, employing a bobbin  10  supported in the inventive bobbin case.  
         [0066]     A bobbin case according to one embodiment of the invention can have an internal frustoconical configuration with a smaller diameter in its lower portion to properly accommodate bobbin  10 . Proper seating and alignment of a correctly wound bobbin in its bobbin case, as may be achieved with this embodiment of the invention can prevent variations in stitching, inconsistent sewing performance, tension variations, cording, and related problems that may otherwise occur.  
         [0067]     The bobbin case of the present invention can also be employed in a relatively simple style of machine such as that shown in Beitzel U.S. Pat. No. 699,067, which is incorporated by reference herein, where the instant bobbin case may replace cup-like spool holder c of Beitzel.  
         [0068]     In the embodiment illustrated in  FIGS. 6-9   a,  a bobbin case pursuant to the present invention, can accommodate bobbin  10  in only one orientation to reduce user error that may lead to thread-handling problems and/or poor stitching. This can be accomplished employing a bobbin such as bobbin  10  which has an end-for-end asymmetry arising from the differences in size of flanges  14  and  16 . In contrast, many known bobbins are reversible end-for-end and can be installed in a bobbin case in more than one way. Incorrect installation while apparently satisfactory to the user may adversely affect sewing quality.  
         [0069]     Referring now to  FIGS. 6-9   a,  the bobbin case there illustrated, referenced  70 , has a cup-like configuration with a sidewall  71  and a mouth  72  through which bobbin  10  may be received into an interior chamber  74  within bobbin case  70 . Bobbin case  70  has a bottom portion  75  structured to retain bobbin  10  in bobbin case  70 . The exterior of bobbin case  70  is structured to be supported in a suitable rotary mechanism such as Rodda et al.&#39;s rotary loop taker  20 , for example by means of a peripheral lip  76 . Externally, bobbin case  70  can have any desired structure consistent with its bobbin-support and thread supply functions.  
         [0070]     Interior chamber  74  of bobbin case  70  is configured to closely fit bobbin  70  for which purpose it has, in its lower portion, a shape which, in the downward direction tapers or reduces in cross-section, being smaller at the bottom of chamber  74 . In height, chamber  74  may approximate the height of bobbin  10  from flange to flange, and desirably may be just sufficient for chamber  74  to completely accommodate bobbin  10 . The cross-sectional shape of bobbin case chamber  74  desirably may conform with the shape of bobbin flanges  14  and  16  and in one useful embodiment is circular. However, it will be understood that chamber  74  need not conform with the bobbin shape at all points of a given horizontal periphery and may so conform at multiple points or portions, or a single major portion of the periphery.  
         [0071]     In the illustrated embodiment of bobbin case  70 , interior chamber  74  has a middle diameter  78  and a bottom diameter  80 . Middle diameter  78  is somewhat larger than bottom diameter  80 . Thus, between middle diameter  78  and bottom diameter  80 , interior chamber  74  has a part-conical or frusto-conical shape. Above middle diameter  78 , the horizontal section of interior chamber  74  is at least as large as middle diameter  78 . Pursuant to the invention, the dimensions and configuration of interior chamber are selected so that bobbin  10  can be properly accommodated and seated in only one orientation. Usefully, the geometry can be such that attempts to seat bobbin  10  in other than the proper orientation result in misalignments or other problems such that it is clearly impossible to operate the sewing machine.  
         [0072]     For example, bottom diameter  80  may be selected to be approximately equal to the diameter of smaller flange  14  so that smaller flange  14  is a close fit into the bottom of chamber  74 . The dimensioning may provide a small clearance sufficient to prevent smaller flange  14  from being gripped by chamber  74  in a way that would interfere with removal of bobbin  10 . Middle diameter  78  may usefully be larger than bottom diameter  80 , and can be somewhat less than the diameter of larger flange  16  of bobbin  10 . The upper portion of interior chamber  74  can be sufficiently large to receive larger flange  16  of bobbin  10  with a small clearance. With these dimensions, bobbin  10  can be properly seated with smaller flange  14  downward. However, if larger flange  16  is downward, the flange will lodge near middle diameter  78 , leaving flange  14  projecting from bobbin case  70 . The projecting flange may render it impossible to assemble the bobbin case into the sewing machine. Nor can bobbin  10  be inserted into bobbin case chamber  74  with hub  12  horizontal and flanges  14  and  16  extending vertically. Thus, there is only one way in which bobbin  10  can be assembled with bobbin case  70 , as is shown.  
         [0073]     Bobbin case  70  as shown in  FIG. 6  can be fabricated from a lightweight, durable wear-resistant synthetic plastic polymer, for example a phenolic resin such as a thermoset phenolic 525 or CB-7843.  
         [0074]     While the described and illustrated embodiment of bobbin case chamber  70  may have an interior chamber  74  which has horizontal cross-sectional surfaces which lie on circles to closely accommodate or fit circular flanges  14  and  16  of bobbin  10 , it will be understood that interior chamber  74  may have other cross-sectional shapes depending upon the shape of flanges  14  and  16 , or other bobbin structures. For example, the cross-sectional shape or shapes could be square, polygonal, or the like or irregular.  
         [0075]     As will be understood by one skilled in the art, the illustrated embodiment of bobbin case  70  of the invention can be employed in a sewing machine having a hook rotating structure and associated support mechanism such as is disclosed in Rodda et al., for lockstitch operation utilizing thread supplied by bobbin  10  from bobbin case  70 , and replacing bobbin case insert  38  described by Rodda et al. The present invention includes such a sewing machine.  
         [0076]      FIGS. 7-8  show bobbin case  70  supported in a rotating hook mechanism  81  of a sewing machine to supply thread (not shown) from bobbin  10  to the sewing machine&#39;s needle, as a lower thread. Conveniently, although not necessarily, the sewing machine of which portions are illustrated in  FIGS. 7-9  may be the same machine as is partially illustrated in  FIGS. 2-5 .  
         [0077]     The sewing machine shown in  FIGS. 7-8  includes a spring guide  82  which cooperates with the bobbin case side wall  71 , over which the thread runs, to guide the lower thread and tension it during sewing. Rotating hook mechanism  81  is supported in a volume beneath the work bed  84  of the sewing machine which volume is closable by a slidable cover  86 . Cover  86  is closed in  FIG. 7  and retracted, or open, in  FIG. 8  to provide access to bobbin  10 , enabling it to be changed when exhausted of thread or when a different thread is required. Cover  86  has a downward retaining rib  88 . Desirably bobbin case  70  and other relevant components are dimensioned to provide a sufficient clearance  90  for the thread to pass as the hook rotates. Other elements of the rotating hook mechanism and the sewing machine can be as is known in the art.  
         [0078]     In use, a user retracts cover  86 , removes an existing bobbin  10  from bobbin case  70 , if present and manually inserts a wound bobbin  10  which has been prepared as shown in  FIG. 5 . Properly oriented, for example as shown in  FIG. 7   a,  with smaller flange  14  downward, bobbin  10  readily drops into place in bobbin case  70 . Thread is drawn from bobbin  70  and positioned in the usual manner to supply lower thread to the needle. Cover  86  can be closed, ready for sewing.  
         [0079]     In the event the user inserts bobbin  10  with an incorrect orientation, for example with larger flange  16  downward, as shown in  FIG. 9  and  FIG. 9   a,  flange  16  lodges near middle diameter and flange  14  projects above work bed  84 . Cover  86  cannot be closed, sewing is prevented and this state of affairs will usually prompt the user to remove, rotate and reinsert bobbin  10  in the correct orientation. Because the direction of winding of the thread on bobbin  10  has been predetermined in the winding operation, the user is assured of sewing with a properly installed and correctly wound bobbin. So long as other components of the sewing machine are functioning properly, the user may reasonably expect to be able to generate quality stitching until bobbin  10  is exhausted of thread and needs changing.  
         [0080]     Additional benefits obtainable with embodiments of novel bobbin case  70  are that it may easily be removed and reinstalled facilitating cleaning and lubricating of the rotating hook mechanism.  
         [0081]     In the above description, where structures are described as having, including, or comprising specific components, or where methods are described as having, including, or comprising specific steps, it is contemplated that structures and methods of the present invention may also consist essentially of, or consist only of, the particular components or steps recited.  
         [0082]     The foregoing detailed description is to be read in light of and in combination with the preceding background and invention summary descriptions wherein information regarding the best mode of practicing the invention may also be set forth and where modifications, alternative and useful embodiments of the invention may be suggested or set forth, as will be apparent to one skilled in the art.  
         [0083]     While illustrative embodiments of the invention have been described above, it is, of course, understood that many and various modifications will be apparent to those of ordinary skill in the relevant art, or may become apparent as the art develops. Such modifications are contemplated as being within the spirit and scope of the invention or inventions disclosed in this specification.