Abstract:
An apparatus for automatically changing a bobbin case on a quilting machine having a hook drive operatively supporting the bobbin case during a stitching operation. The apparatus includes a staging station adapted to support at least one bobbin case normally having a full spool of thread, and a carriage movable between the staging station and the hook drive. A finger is movably mounted on the carriage, and the finger moves a release lever on the bobbin to an unlock position and clamps the release lever at the unlock position. A method of using the above apparatus in an automatic bobbin changing operation is also provided. A controller determines the need for a bobbin change, for example, by counting stitches and calculating the thread remaining on the bobbin. The bobbin change can be carried out between patterns or during a pattern by cutting the bobbin thread or both the top and bottom threads. The sewing of tacking stitches may also be done in sequence with the thread cutting and bobbin changes.

Description:
FIELD OF THE INVENTION 
     The present invention relates to quilting machines, and particularly to an apparatus and methods for automatically changing a bobbin on a quilting machine. 
     BACKGROUND OF THE INVENTION 
     In quilting machines of various types, threads are applied and manipulated on opposite sides of a fabric to form one or more patterns of stitches. The proper formation of the stitches of each series requires the movement and precise timing of cooperating stitching elements. Some quilts are stitched with continuous patterns along webs of material that is later cut, without the need to start and stop the quilting of a pattern in the midst of a quilted product. Many standard mattress covers are quilted on multi-needle quilting machines in this manner. Other patterns start and stop on a quilted product, which might include a number of discrete disconnected pattern components on a given quilted product. Multi-needle quilting machines can quilt mattress covers in this manner, as described in commonly assigned U.S. Pat. Nos. 5,154,130 and 5,544,599, hereby expressly incorporated herein by reference. Comforters and certain more expensive mattress covers are quilted as single panels on single needle quilting machines in this manner, as described in commonly assigned U.S. Pat. Nos. 5,650,916, 5,685,250 and 5,832,849, hereby expressly incorporated by reference herein. When a pattern starts or stops on a product, at the end of the stitching of a pattern, a tack is usually sewn, thread is cut, and the relative position of the fabric and the stitching elements is changed to sew another stitched pattern on the same or on another product. 
     Multi-needle quilting machines and some single needle quilting machines for quilting mattress covers and other quilted products having only one outer finished side use a double lock chain stitch. The chain stitch is formed by poking loops of a bottom thread through loops of a top thread, and can be employed using large spools of top and bottom threads, but because the loops are visible on the underside of the product, one side of the product is unattractive. Single needle machines and some multi-needle machines for quilting comforters and mattress covers and other products use a lock stitch. The lock stitch is formed by passing the bottom thread once through each loop of the top thread, which, by taking up the top thread loop so that the thread crossings are essentially within the quilted material, produces a line of stitches that appear the same from both sides. Forming of a lock stitch requires passing the entire bottom thread supply through each top thread loop. As a result, lock stitch machine use small quantities of thread would on a bobbin so that the top thread loop can be hooked and rotated around the bobbin and hence the single strand of bottom thread. 
     Many lock stitch quilting machines have a common structure in which a reciprocating needle is mechanically coupled to an upper sewing head motor located above a layered fabric. The needle reciprocates through layered fabric and through a needle plate supporting the layered fabric. With a lockstitch quilting machine, a lower sewing head includes a hook drive that is mechanically coupled to a bobbin case containing a spool of thread. The lower sewing head may be linked to and driven by the needle drive motor or by the hook drive motor, synchronized to the needle motion, to move the hook drive around the bobbin case to pick up thread from the spool in synchronization with the motion of the needle and thread below the layered fabric. The thread from the reciprocating needle and the thread from the bobbin case form a lockstitch securing the layers of fabric together in a known manner. 
     The nature of the lockstitch requires that the bobbin thread be reduced to a minimum size in order to allow the thread from the needle to be rotated about the bobbin case thread to form the stitch. The limited size of the bobbin case limits the quantity of thread that can be stored within the bobbin case. Usually, in commercial lockstitch quilting, some scheme is used to alert a machine operator when there is insufficient thread left on the bobbin to quilt a complete quilted product, so that the operator can change bobbins manually before starting a product. Otherwise, it is necessary for the operator to manually operate the machine to cut thread, tack the stitches if necessary, and change bobbins in the middle of a quilted patter. 
     When quilting larger workpieces, for example mattress covers, a particular stitch pattern may require more thread than can be stored in a common, commercially available bobbin case. Therefore, the thread spool and bobbin case would have to be changed in the middle of a workpiece quilting cycle. An manual operation to change a bobbin, particularly in the middle of the quilting of a pattern, requires that a machine operator stop the operation of the upper and lower sewing head motors, manually command the quilting machine to move the sewing heads to a maintenance position and remove the bobbin case with the empty thread spool. Thereafter, the machine operator must install a bobbin case with a full thread spool, command the quilting machine to move the sewing heads back to the position where the bobbin thread ran out and reinitiate the stitching cycle. Such a bobbin case changing operation is labor intensive, time consuming, inefficient, extends the time required for part production and thus, adds significant cost to the production of the workpiece. 
     Therefore, there is a need to provide apparatus and methods for automatically changing a bobbin case on a quilting machine, thereby substantially improving its efficiency. 
     SUMMARY OF INVENTION 
     The present invention provides methods and apparatus for operating a quilting machine that are more efficient than known methods and apparatus. The methods and apparatus of the present invention improve the state of automation of a lock stitch quilting machine by reducing the labor required, reducing the time required to stitch patterns and thus, substantially reducing the production of patterns stitched with the quilting machine. The invention is especially useful when stitching large patterns of layered fabric which exceed the amount of thread stored in the bobbin case and require the bobbin case be changed in the middle of stitching the pattern. 
     In accordance with the principles of the present invention and the described embodiments, the invention provides an apparatus that automatically changes a bobbin case on a quilting machine having a hook drive operatively supporting the bobbin case during a stitching operation. The apparatus includes a bobbin staging station adapted to support at least one bobbin case normally having a full spool of thread, and a carriage movable between the bobbin staging station and the hook drive. A finger is movably mounted on the carriage, and the finger moves a release lever on the bobbin case to an unlock position and clamps the release lever at the unlock position. 
     In one aspect of the invention, the finger engages a rear side of the release lever and pivots the release lever to the unlock position. In another aspect of the invention, the lever clamps the release lever against a stop, for example, a stop made from a resilient material. In a further aspect of the invention, the finger is operated by a reciprocating cylinder. In a still further aspect of the invention, the carriage is movable in mutually perpendicular directions in moving between the bobbin staging station and the hook drive. 
     In another embodiment, the present invention includes a method of automatically changing a bobbin case on a quilting machine having a hook drive operatively supporting the bobbin case during a stitching operation. The method first moves a carriage to a position adjacent a first bobbin case mounted on the hook drive. Next the release lever of the first bobbin case is mechanically pivoted to an unlock position, thereby unlocking the first bobbin case from the hook drive. The release lever of the first bobbin case is then mechanically clamped in the unlock position; and the carriage is moved away from the hook drive, thereby removing the first bobbin case from the hook drive. The release lever of the first bobbin case is then unclamped, thereby permitting the first bobbin case to drop from the carriage; and the carriage is moved to a position adjacent a second bobbin case. The release lever of the second bobbin case is mechanically pivoted to the unlock position, and the release lever of the second bobbin case is mechanically clamped at the unlock position. The carriage is then moved to the location adjacent the hook drive; and the release lever of the second bobbin case is unclamped, thereby mounting the bobbin case onto the hook drive. 
     Thus the method and apparatus of the present invention automatically changes a bobbin case on a quilting machine with the advantages of eliminating the labor, time and cost of changing bobbin cases manually in the middle of stitching a large pattern on a lock stitch quilting machine. 
     The invention also provides automatic operation of the bobbin change mechanism between the stitching of different patterns, or during the stitching of a pattern by determining the need therefore through, for example, the counting of stitches. The bobbin changes may be performed in sequence with the cutting of the bobbin thread only or the cutting of both top and bottom threads, and/or in sequence with the sewing of tacking stitches before and/or after the thread cut and bobbin change. 
     Various additional advantages, objects and features of the invention will become more readily apparent to those of ordinary skill in the art upon consideration of the following detailed description of the presently preferred embodiments taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of an automatic bobbin changer mounted in relation to known components of a quilting machine in accordance with the principles of the present invention. 
     FIG. 2 is a perspective view partially broken away of the automatic bobbin changer of FIG. 1, however, the hook drive is not shown in FIG.  2 . 
     FIG. 3 is another perspective view of the automatic bobbin changer of FIG.  1  and includes a schematic block diagram of control elements operating the bobbin changer. 
     FIG. 4 is a partial cross-sectional view taken along line  4 — 4  of FIG.  3  and illustrating a first operation of the automatic bobbin changer of FIG.  1 . 
     FIG. 5 is a side view of the carriage of the automatic bobbin changer of FIG.  1 . 
     FIG. 6 is a partial cross-sectional view taken along line  4 — 4  of FIG.  3  and illustrating a second operation of the automatic bobbin changer of FIG.  1 . 
     FIG. 7 is a perspective view of only the bobbin staging station of the automatic bobbin changer of FIG.  1 . 
     FIGS. 8A-8I illustrate each step of a cycle of operation of the bobbin changer of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The components of FIG. 1 that are shown in phantom are known quilting machine components that form a lockstitch in a known manner. The layers of fabric  20  to be stitched are laid out on top of a needle plate  22  of a quilting machine. A needle  24  is mounted in an upper sewing head motor and drive (not shown) which is located above a presser foot  28  in a known manner. The needle  24  and thread  25  reciprocate vertically through a hole  26  in the presser foot  28 , through the layers of fabric  20  and then through a hole  30  of the needle plate  22 . When sewing a lockstitch, a lower sewing head motor  34  is mechanically coupled to a hook drive  36  supporting a bobbin case  38  containing a spool of thread (not shown). The lower sewing head motor  34 , in a known manner, moves the hook drive  36  around the bobbin case  38  to pick up thread (not shown) from the spool in synchronization with the motion of the needle  24  and the thread  25  below the layered fabric. The thread  25  from the reciprocating needle  24  and the thread from the bobbin case  38  are thus formed into a lockstitch securing the layers of fabric  20  together. 
     The motion of the thread  25  with respect to the lower thread from the bobbin case  38  requires that the bobbin case be of a relatively small size. The small size limits the quantity of thread that can be stored in the bobbin case. Consequently, a bobbin case may run out of thread in the middle of sewing the layered fabric  20 , require changing. When a quilting machine control, such as a programmed controller  140  (FIG.  3 ), determines that the spool within the bobbin case  38  is empty, a bobbin changer  40  is commanded by the control to execute a bobbin change cycle. In the bobbin change cycle, a carriage  42  is moved from a rest position, as illustrated, upward to a position opposite the hook drive  36 , and the bobbin case  38  is removed from the hook drive  36  to the carriage  42 . The carriage  42  then moves to a position over a used bobbin tray  44 , and the bobbin case  38  with the used thread spool is dropped into the tray  44 . The carriage  42  then moves into alignment with a bobbin staging station  46 , which is the position illustrated in FIG.  1 . The staging station  46  contains a plurality of bobbin cases  38  each containing a full spool of thread. At the staging station, the carriage  42  picks up one of the full bobbin cases  38 , moves it to a position opposite the hook drive  36  and loads the full bobbin case  38  onto the hook drive. The quilting machine is then ready to resume its sewing operation. 
     Referring to FIGS. 2 and 3, the automatic bobbin changer  40  has a mounting block  50  that functions to mount the automatic bobbin changer  40  to a lower sewing head base mount  52  (FIG. 1) by means of fasteners  54 . The mounting block  50  is rigidly connected to a first drive  56 , for example, a horizontal cylinder and upper and lower horizontal guides,  58 ,  60 , respectively. The horizontal cylinder  56  is a fluid operated cylinder, for example, a cylinder operated with pressurized air and commercially available as part no. TE-021 from Bimba Manufacturing of Monee, Illinois. A horizontal slide  62  is rigidly connected to a distal end of a horizontal cylinder rod  64  extending from the horizontal cylinder  56 . The horizontal slide  62  is also connected to the distal ends of upper and lower rails  66 ,  68  that slidingly mount within the respective guides  58 ,  60 . Thus, the cylinder  56  operates to translate the horizontal slide  62  back and forth along a first axis of motion, for example, in the horizontal direction. 
     A second drive, which includes a vertical cylinder  74 , is rigidly mounted at its ends within a C-shaped frame  72  on the horizontal slide  62 . The vertical cylinder  74  is a fluid operated cylinder, for example, a cylinder operated with pressurized air and commercially available as part no. NCY2B6H-1.75 from SMC Pneumatics of Indianapolis, Indiana. A cylinder slide  70  is magnetically coupled to a piston within the cylinder  74 . A vertical guide rail  76  is mounted to an interior portion of the C-shaped frame  72  and, referring to FIG. 4, has a bearing slide  77  slidably mounted thereon. The bearing slide  77  and cylinder slide  70  are rigidly attached to a connecting link or plate  79 , for example, by welding, with fasteners or other appropriate means. The connecting plate  79  is attached to the carriage  42  by fasteners  78  (FIG.  3 ). The assembly of the cylinder  74 , guide rail  76  and connecting plate  79  function to translate the carriage  42  along a second axis of motion, for example, up and down in a vertical direction. Thus, the horizontal cylinder  56  and the vertical cylinder  74  are used to move the carriage  42  along mutually perpendicular axes of motion between the hook drive  36  and the bobbin staging station  46  (FIG.  1 ). 
     Once the carriage is aligned with either the hook drive  36  or the bobbin staging station  46 , the bobbin case  38  containing the thread spool is transferred to or from the carriage  42 . Referring to FIGS. 4-6, a finger cylinder  80  is mounted in a bore  82  of the carriage  42 , for example, by threads  84  or other appropriate structure. The fluid cylinder  80  is a fluid operated cylinder, for example, a pressurized air operated cylinder with an internal return spring and commercially available as part no. AL2RRO-1/4 from Watson Pneumatics of Cleveland, Ohio. A finger  86  is mounted on a pivot pin  87  within a slot  88  in the forward side  90  of the carriage  42 . When the finger  86  is at its first disengaged position as illustrated in FIG. 4, the outer end or tip  92  of the finger  86  extends slightly beyond the plane of the forward side  90  of the carriage  42 . The inner end  94  of the finger  86  is pivotally mounted to a distal end  96  of the rod  98  extending from the finger cylinder  80 . While the finger  86  may be mounted to the finger cylinder rod  98  with several different constructions, in this embodiment, the inner end  94  of the finger  86  has an elongated slot  100 . A pin  102  extends through the slot  100  and is fixed at its ends to opposite sides of a U-shaped clevis  104  mounted on the distal end  96  of the finger cylinder rod  98 . A stop  106  in the form of a deformable, resilient pad, for example, a rubber pad, is rigidly fixed within the slot  88  of the carriage  42 . 
     The bobbin case  38  is operatively connected to the hook drive  36  in a known manner. A release lever  108  is pivotally mounted to the front of the bobbin case  38 , and an outward, clockwise pivoting motion of the lever  108  causes a locking tab  110  to translate to the left as viewed in FIG.  4 . The leftward translation moves the locking tab  110  out of a slot  112  of a center shaft  114  of the hook drive  36 . Thus, pivoting the release lever  108  from a first, lock position outward to a second, unlock position, thereby unlocking the bobbin case from the hook drive  36  and permitting the bobbin case  38  to be removed therefrom. 
     Referring to FIGS. 2 and 3, when the carriage  42  has been moved to its upper, inward position, the carriage  42  is immediately adjacent the hook drive  36 . As illustrated in FIG. 4, the outer end  92  of the finger  86  is positioned immediately adjacent the movable end of the bobbin case release lever  108  located at its lock position. Referring to FIG. 6, actuating the finger cylinder  80  causes the finger cylinder rod  98  to extend, thereby pivoting the finger  86  in a generally counterclockwise direction as viewed in FIG.  6 . As the finger  86  begins to pivot, its outer end  92  engages a rear side  117  of the pivoting lever  108  of the bobbin case  38 . The pivoting finger  86  applies a force against the rear side of the lever  108 , thereby pivoting the release lever  108  outward to the unlock position. The finger  86  holds the release lever  108  in the unlock position by clamping the lever  108  against a stop surface  105  on the stop  106 . Further, the bobbin case  38  is pulled against the forward side  90  of the carriage  42 , thereby securing the bobbin case  38  to the carriage  42 . The release lever  108  is also supported between the upper and lower walls  116 ,  118 , respectively, of the slot  88  shown in FIG.  5 . Thus, the bobbin case  38  is now being carried by the carriage  42 ; and by actuating the horizontal cylinder  56 , the bobbin case  38  is removed from the hook drive  36  and carried to another location, for example, to the used bobbin tray  44  (FIG.  1 ). 
     To release the bobbin case  38  from the carriage  42 , the finger cylinder  80  is actuated so that the finger cylinder rod  98  retracts back into the cylinder  80 , and the finger  86  rotates clockwise as viewed in FIG. 6, to the position illustrated in FIG.  4 . That motion of the finger  86  releases the lever  108  from the stop  106  which allows the lever  108  to return to its lock position as illustrated in FIG. 4; and the bobbin case  38  is released from, and no longer supported by, the carriage  42 . 
     Referring to FIG. 7, the bobbin staging station  46  has a staging rod  120  with one end rigidly connected to the mounting block  50 . The rod  120  has a distal end  122  with a circular, cross-sectional profile. Immediately behind the distal end  122 , the shaft  120  is relieved or cutaway, beginning at  124 , to form a noncircular, cross-sectional profile. The cutout  126  formed by the noncircular, cross-sectional profile has a flat surface that extends longitudinally along the rod to a location, at  128 , where the circular, cross-sectional profile begins again. A pair of guide rods  130  are rigidly secured at one end to the mounting block  50 . The guide rods  130  are spaced to extend through a cutaway portion  132  in the outer periphery of the bobbin case  38 , thereby maintaining the bobbin case  38  in the desired angular orientation on the staging shaft  120 . 
     As previously discussed with respect to FIGS. 4-6, with the release lever  108  of the bobbin case  38  pivoted outward to its unlock position, the bobbin case  38  can readily slide over the circular, distal end  122  of the staging shaft  120 . After the bobbin case is mounted on the staging shaft  120 , the lever  108  is released; and as the release lever  108  returns to its lock position, it moves a locking tab into the cutout  126  of the staging shaft  120 , thereby prohibiting the bobbin case  38  from being moved outward past the circular, distal end  122 . A biasing element, for example, a compression spring  134 , has one end mounted in a bore  136  of the mounting block  50  and an opposite end contacts a rear side  138  of the bobbin case  38 . Thus, the spring  134  applies a biasing force to maintain the bobbin case  38  as close as possible to the circular, distal end  122  of the staging shaft  120 . 
     In use, the quilting machine control  140  (FIG. 3) keeps track of the thread being used from the spool of thread in the bobbin case  38 . The controller  140  typically will be a programmed controller of the quilting machine that contains data of the shapes of the patterns to be quilted, and can contain other parameters for scheduling and operating the machine for different products to be quilted. The quilting machine control  140  is programmed with the length of stitch and keeps track of the relative position of the presser foot  28  with respect to the needle plate  22  representing the thickness of the layer of material  20  being sewn. Therefore, the control  140  is able to determine the amount of thread being used from the bobbin spool with each stitch. The number of stitches can be determined in one of several ways depending on the data available on the quilting machine. For example, each reciprocation of the needle  24  or rotation of the upper sewing motor can be detected and counted by the control  140 . Alternatively, each cycle of the hook drive  36  can be detected directly from the motion of the hook drive or by the operation of the lower sewing head motor  34 . Finally, the number of stitches in a pattern and the amount of thread on a full spool is known and programmed into the quilting machine control  140 . Given the above data or by other methods known in the art, the quilting machine control  140  is able to determine a bobbin stitch count, that is, the number of stitches that can be sewn starting with a full spool of thread on the bobbin before the spool of thread reaches a state at which it should be changed. 
     When the control  140  determines that a bobbin change is needed, the change may be implemented in one of a number of sequences. A bobbin change may be implemented by determining that the amount of thread left on a bobbin is less than that needed to complete the next scheduled product. When such a determination is made, a bobbin change can be caused to be executed between products, for example, after the pattern of one product has been completed, tack stitches are sewn, and the thread has been cut, but before the pattern is started on the next product. Such a bobbin change can be executed also when a determination that bobbin thread must be changed for another reason, such as a scheduled change in color or thread type for the next product. 
     A bobbin change may also be caused to be executed by the quilting machine controller  140 , during the quilting of a pattern upon the determination that the thread on the bobbin is running out. When this determination occurs, the control  140  may cause the pattern stitching to stop, the bottom thread from the bobbin to be cut, and the bobbin to be changed, whereupon the pattern stitching is resumed. The thread cutting may involve the cutting of both top and bottom threads just as they would be cut at the end of a pattern, or with only the bottom thread cut. 
     When all threads are cut, a standard procedure is to stop the machine with the top thread extending from the needle eye through the needle plate hole below the fabric, around the hook and back through the needle plate hole to the last stitch formed in the material. A cutter below the needle plate then typically moves against the threads, displaces the top thread extending from the needle and then cuts both the top thread that extends through the hole in the needle plate from the material and the bottom thread that extends through the hole from the material to the bobbin. Usually it will be desirable to sew a tack in the pattern before cutting the thread. Also, it may be desirable to sew another tack immediately after resuming the stitching of the pattern following a bobbin change. 
     A bobbin change may be implemented by cutting only the bottom thread. This may be done by stopping the machine, upon a determination by the controller that a bobbin change is necessary in the midst of quilting a pattern, with the needle in the raised position typically above the presser foot, opposite the needle plate from the material, with the top thread released from the hook and the top thread take-up having withdrawn the top thread slack from below the material. With only the bottom thread extending through the hole in the needle plate to the bobbin, the bottom thread can be cut. The sewing of tack stitches before or after the bottom thread is cut may be carried out, but is not always necessary. 
     During a stitching cycle, the carriage  42  is generally at its lower, inner position, as illustrated in FIG. 8A, to reduce any potential for interference with the hook drive  36 . In order to provide the most efficient bobbin change cycle, since the carriage must be moved from its starting, rest position adjacent the staging shaft  120  to a position adjacent the hook drive  36 , the quilting machine control  140  initiates a bobbin change cycle before it detects a bobbin change stitch count. So that the carriage  42  is ready to effect a bobbin change as soon as the sewing motors and the hook drive  36  stop, the bobbin change cycle is initiated before the detection of a bobbin change stitch count by a period of time substantially equal to the time required to move the carriage  42  from its rest position to a position opposite the hook drive  36 . At that time, the control  140  provides a signal on an output  142  to a horizontal solenoid valve  144 , thereby switching the state of the valve  144 . Pressurized fluid is appropriately ported through the valve  144  between a pressurized fluid source  146  and the horizontal cylinder  56 . The horizontal cylinder  56  is activated to move the horizontal slide  62  and carriage  42  to a lower, outward position as illustrated in FIG.  8 B. 
     Next, the control  140  provides a signal on an output  152  to a vertical solenoid valve  154  switching the state of the valve  154 . Pressurized fluid is appropriately ported through the valve  154  between a pressurized fluid source  146  and the vertical cylinder  74 . The vertical cylinder  74  is activated to move the carriage  42  to an upper, outward position as illustrated in FIG.  8 C. The control  140  then, again, provides a signal on an output  142  to the horizontal solenoid valve  144  causing the valve  144  to operate the horizontal cylinder  56  to move the horizontal slide  62  and carriage  42  to an upper, inward position immediately adjacent the end of the hook drive  36  as illustrated in FIGS. 4 and 8D. 
     Substantially simultaneously with the carriage arriving at the upper, inward position of FIG. 8D, the quilting machine control  140  detects the bobbin change stitch count and provides command signals to stop the sewing head motors. Next, the quilting machine control provides a signal on an output  148  to a finger solenoid valve  150  switching the state of that valve. Fluid is ported through the valve  150  to the finger cylinder  80 , thereby actuating the cylinder  80 , rotating the finger  86  and pivoting the release lever  108  outward to the unlock position as previously described. That action disengages the bobbin case  38  from the hook drive  36  (FIG. 6) and clamps the bobbin case with the used spool of thread to the carriage  42 . Next, the quilting machine control  140  provides a signal on the output  142  to the horizontal solenoid valve  144  changing the state of the solenoid valve  144  to reverse the operation of the horizontal cylinder  56 . Thus, the horizontal slide  62 , carriage  42  and bobbin case  38  are moved outward, thereby removing the bobbin case  38  from the shaft  114  of the hook drive  36 . The carriage  42  and bobbin case  38  are moved outward to the position illustrated in FIG.  8 E. Thereafter, the quilting machine control  140  provides an output control signal on the output  152  to a vertical solenoid valve  154  switching the state of the valve  154  and actuating the vertical cylinder  74  to lower the carriage  42  and bobbin case  38  with the used spool of thread to a position immediately over the used bobbin tray  44  as shown in FIG.  8 F. 
     The quilting machine control  140  then supplies a control signal over the output  148  to the finger solenoid valve  150  switching the state of that valve to reverse the operation of the finger cylinder  80 , thereby rotating the finger  86  back to its initial position (FIG.  4 ). As the finger  86  moves back to its initial position, it releases the lever  108  of the bobbin case  38 ; and the bobbin case  38  with the used spool of thread drops into the used bobbin tray  44  (FIG.  8 G). Next, the quilting machine control  140  provides a control signal over the output  142  to operate the horizontal solenoid valve  144  such that the horizontal cylinder  56  moves the horizontal slide  62  and carriage  42  inward to a position immediately adjacent the bobbin staging shaft station  46  (FIG.  8 H). The quilting machine control  140  then actuates the finger solenoid valve  150  to cause the finger solenoid  80  to again rotate the finger  86  to engage a release lever  108  of a bobbin case  38  having a full spool of thread. The pivoting motion of the finger  86  moves the release lever  108  to the unlock position which unlocks the bobbin  38  from the staging shaft  120 ; and simultaneously, the pivoting finger clamps the release lever  108  against the stop  106  to hold the bobbin case  38  on the carriage. Thereafter, the quilting machine control  140  operates the horizontal and vertical solenoid valves  144 , 154  to cause the respective horizontal and vertical cylinders  56 ,  74  to move the carriage  42  carrying the bobbin case  38  with the full spool of thread first, outward to remove the bobbin case  38  from the staging shaft  120  and then, up and inward to a position adjacent the end of the hook drive  36  as shown in FIG.  81 . 
     As the horizontal slide  62  and carriage  42  carrying the bobbin case  38  with the full spool of thread move inward, the bobbin case  38  is slid over the center shaft  114  of the hook and drive  36  such that the locking tab  110  is placed in alignment with the slot  112  on the shaft  114 . Thereafter, the quilting machine control  140  operates the finger solenoid valve  150  to return the finger  86  back to its rest position, thereby releasing the lever  108  from its unlock position. The lever  108  is spring biased back to its lock position, thereby locking the bobbin case  38  with the full spool of thread on the center shaft  114 . The quilting machine control  140  then provides a command signal to the sewing head motors to initiate the sewing cycle; and substantially simultaneously, the quilting machine control  140  then operates the horizontal solenoid valve  144  to actuate the horizontal cylinder  56  in a manner to move the horizontal slide  62  and carriage  42  away from the hook drive  36  to its upper, outer position which was previously shown in FIG.  8 C. Immediately thereafter, the control  140  provides further signals to the vertical and horizontal solenoid valves  154 , 144  to operate the respective vertical and horizontal cylinders  74 ,  56  to move the carriage  42  back to its starting rest position illustrated in FIG.  8 A. 
     While the present invention has been illustrated by a description of one embodiment and while that embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the spirit and scope of the invention will readily appear to those skilled in the art. For example, in the described embodiment, the cylinders  56 ,  74  and  80  are fluid cylinders operated with pressurized air. As will be appreciated hydraulic cylinders could also be used. In addition, the commercial cylinders could be replaced by electric motor and rack and pinion drives or other known mechanisms that convert the rotary motion of the electric motor to the desired linear motion. 
     In the described embodiment, the stop is a resilient pad; however, as will be appreciated, a nonresilient pad may also be used if it is positioned to provide the desired clamping of the bobbin case release lever. Further, the described embodiment illustrates a single needle, however, as will be appreciated, the bobbin changer of the present invention may also be used on a quilting machine having multiple needles. Also, as will be recognized, while the bobbin changing apparatus is described herein with respect to a quilting machine, certain aspects of the bobbin changing apparatus may also have utility on nonquilting machines. 
     Therefore, the invention in its broadest aspects is not limited to the specific detail shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.