Patent Publication Number: US-2004055521-A1

Title: Sewing machine

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a sewing machine such as a quilting machine.  
       [0002] In a typical sewing machine such as a quilting machine, a needle plate (a type of sewing fabric supporting plate), and a vertically movable holding plate (a kind of sewing fabric supporting plate) is supported above the needle plate. A needle hole of the same diameter is formed in each of the needle plate and the holding plate. The needle holes are located to correspond to each other. When a sheet of fabric that is held between the needle plate and the holding plate is being fed, a needle to which an upper thread is passed through is vertically reciprocated between a top dead center above the holding plate and a bottom dead center below the needle plate, while passing through the needle holes. Accordingly, a desired sewing pattern is formed on the fabric.  
       [0003] To meet the demands for shorter sewing time, the fabric feeding speed at the sewing section has been significantly increased. For example, in a case of a fabric feeding mechanism for feeding fabric of an ordinary thickness, the rotation speed of the driveshaft has been increased to 1200 rpm from conventional 500 rpm. Further, to meet the demands for wide variety of sewing patterns, the sewing section not only moves the fabric in the feeding direction but also repetitively moves the fabric by small amounts in a direction perpendicular to the feeding direction while keeping the fabric strained.  
       [0004] Therefore, when the needle, which is vertically moved between the top dead center and the bottom dead center, is penetrating the fabric, fast repetitive movements of the fabric pulls the needle. This displaces the needle from the correct position. Such a displacement of the needle changes the relative positions of the needle at the bottom dead center and the looper (or a shuttle). As a result, stitch skipping occurs in the sewing pattern, and some products will be wasted.  
       SUMMARY OF THE INVENTION  
       [0005] Accordingly, it is an objective of the present invention to provide a plate for supporting sewing fabric in a sewing machine, which plate forms sewing patterns without creating stitch skipping.  
       [0006] To achieve the foregoing objectives, a first embodiment of the present invention provides a sewing fabric supporting plate for a sewing machine having a supporting plate portion and a needle. The supporting plate portion contacts sewing fabric that is being fed in a predetermined direction during a sewing operation, thereby supporting the fabric. The needle is vertically moved between a top dead center above the supporting plate portion and a bottom dead center below the supporting plate portion. The supporting plate portion has a needle hole through which the needle passes through. The needle hole is formed such that a lower end opening is smaller than an upper end opening.  
       [0007] A second embodiment of the present invention provides a lower thread supply control apparatus for a sewing machine. In synchronization with vertical movements of needle through which an upper thread is drawn, a blade portion of a looper through which a lower thread is drawn is moved back and forth to form predetermined stitches on sewing fabric. The lower thread supply control apparatus controls the supply state of the lower thread such that the lower thread drawn from a lower thread supply source is supplied in a predetermined state. The apparatus includes a lower thread guide and a lower thread interfering member. The lower thread passes through the lower thread guide such that the lower thread is supplied from the lower thread supply source to the looper by way of a predetermined lower thread path. The lower thread interfering member is capable of engaging with the lower thread passing through the lower thread guide, and constantly moves toward a predetermined end of movement. When the lower thread interfering member engages with the lower thread, the lower thread passes through the lower thread guide while being pressed against the lower thread guide.  
       [0008] A third embodiment of the present invention provides an eccentric mechanism for a sewing machine having an eccentric shaft, an eccentric member, and a connecting rod. The eccentric member is fixed to the eccentric shaft to integrally rotate with the eccentric shaft. The eccentric member includes an eccentric cylindrical portion. The eccentric cylindrical portion has a central axis displaced from a rotation axis of the eccentric shaft. The connecting rod has a sliding ring portion and a rod portion. The sliding ring portion of the connecting rod is rotatably fitted to the eccentric cylindrical portion of the eccentric member. The rod portion of the connecting rod is coupled to at least one of a needle driving mechanism and a looper driving mechanism. The eccentric mechanism converts rotation of the eccentric shaft into linear reciprocation of the connecting rod. A material of at least one of the eccentric member and the connecting rod is one of aluminum, an aluminum alloy, titanium, a titanium alloy, and ceramics.  
       [0009] A fourth embodiment of the present invention provides a sewing machine having a sewing section for sewing fabric, a feeding section that feeds fabric to the sewing section, and a winding section that sends out material sewn by the sewing section while winding the sewn material. The winding section includes a drive roller, a free roller, a free pulley, a rotation pulley, urging means and a timing belt. The drive roller has a drive pulley. The drive pulley rotates integrally with the drive roller. The free roller is rotatable about its axis. The free roller is capable of approaching and separating from the drive roller. The free pulley rotates integrally with the free roller. The rotation pulley is rotatable about its axis. The rotation pulley is capable of approaching and separating from the drive pulley. The urging means urges the rotation pulley away from the drive pulley. The timing belt couples the free pulley, the drive pulley, and the rotation pulley to one anther. The urging means urges the rotation pulley, thereby adjusting the spaces among the drive pulley, the free pulley, and the urging pulley by means of the timing belt. In accordance with the space adjustment, the space between the drive roller and the free roller is adjusted.  
       [0010] A fifth embodiment of the present invention provides a sewing machine having a needle, a looper, and a needle vibration limiting member. An upper thread is drawn through the needle, and the needle reciprocates between a top dead center above a needle plate and a bottom dead center below the needle plate. The looper having a blade portion is located below the needle plate and corresponds to the needle. When the needle reciprocates, the blade portion through which a lower thread is drawn moves back and forth in a laterally adjacent area of the needle along a path intersecting the reciprocation path of the needle, thereby, together with the needle, forming predetermined stitches, in which the lower thread is interlooped with an upper thread, on sewing fabric that is moving on the needle plate. The needle vibration limiting member is located adjacent to the blade portion. The space between the needle vibration limiting member and the blade portion is substantially equal to the outer diameter of the needle. When the needle reciprocated in the vicinity of the bottom dead center, the needle vibration limiting member moves back and forth in an area opposite from the blade portion, and cooperates with the blade portion to hold the needle from both sides.  
       [0011] A sixth embodiment of the present invention provides a sewing machine having a sewing section. The sewing section includes a needle plate, a needle, and a looper. The needle reciprocates between a top dead center above the needle plate and a bottom dead center below the needle plate. The looper is located below the needle plate. The sewing machine further includes a thread cutting blade. Below the needle plate, the thread cutting blade is moved between a cutting position, where the blade enters a space between the needle plate and the looper, and a standby position, where the blade is laterally adjacent to the looper.  
       [0012] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0013] The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:  
     [0014]FIG. 1 is a diagrammatic view illustrating a quilting machine according to a first embodiment;  
     [0015]FIG. 2 is a partial cross-sectional view illustrating a sewing section, in which needles are being lowered;  
     [0016]FIG. 3 is a partial cross-sectional view illustrating the sewing section of FIG. 2, in which the needles are at bottom dead centers;  
     [0017]FIG. 4 is a partial plan view illustrating a holding plate;  
     [0018]FIG. 5 is a front view illustrating a fitted member;  
     [0019]FIG. 6 is a schematic perspective view illustrating paths of lower threads according to a second embodiment, in which each path extends from a lower thread bobbin to a looper;  
     [0020]FIG. 7 is a diagrammatic view showing a lower thread supply control apparatus;  
     [0021]FIG. 8( a ) is a left side view showing an operation of a looper, in which a needle is lowered below a needle plate;  
     [0022]FIG. 8( b ) is a front view showing the looper and the needle of FIG. 8( a );  
     [0023]FIG. 8( c ) is a top plan view showing the looper and the needle of FIG. 8( a );  
     [0024]FIG. 9 is a diagrammatic view illustrating a quilting machine provided with an eccentric mechanism according to a third embodiment;  
     [0025]FIG. 10 is a perspective view showing the eccentric mechanism;  
     [0026]FIG. 11( a ) is a front view showing an eccentric member;  
     [0027]FIG. 11( b ) is a side view showing the eccentric member;  
     [0028]FIG. 12( a ) is a front view showing a connecting rod;  
     [0029]FIG. 12( b ) is a side view showing the connecting rod;  
     [0030]FIG. 13( a ) is a front view showing a first spacer;  
     [0031]FIG. 13( b ) is a side view showing the first spacer;  
     [0032]FIG. 14( a ) is a front view showing a second spacer;  
     [0033]FIG. 14( b ) is a side view showing the second spacer;  
     [0034]FIG. 15( a ) is a front view showing a stopper plate;  
     [0035]FIG. 15( b ) is a side view showing the stopper plate;  
     [0036]FIG. 16( a ) is a side view illustrating a winding section of a quilting machine according to a fourth embodiment;  
     [0037]FIG. 16( b ) is another side view illustrating the winding section of the quilting machine according to the fourth embodiment;  
     [0038]FIG. 17 is a front view showing the disassembled winding section;  
     [0039]FIG. 18( a ) is a side view, with a part cut away, illustrating the dissembled winding section;  
     [0040]FIG. 18( b ) is a plan view showing an urged pulley of the winding section;  
     [0041]FIG. 19( a ) is a perspective view illustrating a looper according to a fifth embodiment;  
     [0042]FIG. 19( b ) is a partial cross-sectional view illustrating the looper;  
     [0043]FIG. 20( a ) is a plan view showing the looper;  
     [0044]FIG. 20( b ) is a front view showing the looper;  
     [0045]FIG. 21( a ) is a left side view showing an operation of the looper and other members, in which a needle is at a bottom dead center;  
     [0046]FIG. 21( b ) is a front view showing an operation of the looper and other members, in which the needle is at the bottom dead center;  
     [0047]FIG. 22( a ) is a left side view showing an operation of the looper, in which the needle starts being lifted from the bottom dead center;  
     [0048]FIG. 22( b ) is a front view showing an operation of the looper, in which the needle starts being lifted from the bottom dead center;  
     [0049]FIG. 23( a ) is a left side view showing an operation of the looper, in which the needle is at a top dead center;  
     [0050]FIG. 23( b ) is a front view showing an operation of the looper, in which the needle is at the top dead center;  
     [0051]FIG. 24( a ) is a left side view showing an operation of the looper, immediately before the needle reaches the bottom dead center;  
     [0052]FIG. 24( b ) is a front view showing an operation of the looper, immediately before the needle reaches the bottom dead center;  
     [0053]FIG. 25( a ) is a bottom view illustrating a spreader according to a sixth embodiment;  
     [0054]FIG. 25( b ) is a bottom view showing a thread cutter;  
     [0055]FIG. 25( c ) is a front view showing the thread cutter;  
     [0056]FIG. 26 is a bottom view illustrating a part of a needle plate and a thread cutting device;  
     [0057]FIG. 27( a ) is a side view showing the needle plate and the thread cutting device;  
     [0058]FIG. 27( b ) is an enlarged partial cross-sectional view showing the needle plate and the thread cutting device;  
     [0059]FIG. 28( a ) is a left side view showing an operation, in which the needle is at a top dead center, and the thread cutting blade is at a non-cutting position;  
     [0060]FIG. 28( b ) is a front view showing an operation, in which the needle is at the top dead center, and the thread cutting blade is at the non-cutting position;  
     [0061]FIG. 29( a ) is a left side view showing an operation, in which the thread cutting blade is at a cutting position; and  
     [0062]FIG. 29( b ) is a front view showing an operation, in which the thread cutting blade is at the cutting position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0063] A plate for holding fabric in a quilting machine  10  according to a first embodiment of the present invention will now be described with reference to FIGS.  1  to  5 .  
     [0064]FIG. 1 is a schematic view showing the quilting machine  10  according to the first embodiment. As shown in FIG. 1, a roll of middle fabric sheet  11 , which is a thin cotton sheet, is provided at an end of the quilting machine  10 . A winding section  313  is provided at the other end of the quilting machine. Feed rollers  12  are provided at a center of the quilting machine  10  at predetermined intervals. The middle fabric sheet  11  is sent to a product receiving section (not shown) provided adjacent to the winding section  313  through the rollers  12  and the winding section  313 . A lower fabric sheet  14  is fed from below the middle fabric sheet  11  by means of the feed rollers  12 . The lower fabric sheet  14  is sent to the product receiving section through the winding section  313 . An upper fabric sheet  15  is fed from above the middle fabric sheet  11  by means of the feed rollers  12 . The upper fabric sheet  15  is sent to the product receiving section through the winding section  313 . In this embodiment, the middle fabric sheet  11 , the lower fabric sheet  14 , and the upper fabric sheet  15  correspond to sewing fabric.  
     [0065] A sewing section  16  is provided between the feed rollers  12  and the winding section  313 . The sewing section  16  sews the lower fabric sheet  14 , the middle fabric sheet  11 , and the upper fabric sheet  15 , which are fed from the feed roller  12 , to make a quilting product. As shown in FIGS. 2 and 3, the sewing section  16  has a needle plate (fabric supporting plate)  21 , a holding plate member (fabric supporting plate)  22 , vertically movable needles  24 , and reciprocating loopers  26 . Upper threads (needle threads) are drawn through the needles  24 . Lower threads (looper threads) are drawn through the loopers  26 .  
     [0066] The needle plate  21  is a flat aluminum plate horizontally fixed in the sewing section  16 . The entire needle plate  21  forms a supporting plate portion that contacts and supports the sewing fabric including the middle fabric sheet  11  from below. Referring to FIG. 2, pairs of needle holes  27  (only one pair is shown) are formed in the needle plate  21 . The pairs of the needle holes  27  are arranged at predetermined intervals along a fabric feeding direction. The needle holes  27  of each pair are arranged at a predetermined distance along a direction perpendicular to the fabric feeding direction, or along the direction coming out of and going in the elevation of FIG. 2.  
     [0067] As shown in FIG. 2, each needle hole  27  is tapered such that its cross-section along a plane containing the axis of the hole  27  (hereinafter, also referred to as a vertical cross-section) narrows toward the lower end. Each needle hole  27  has an upper opening  27   a  towards the top dead center of the needles  24  and a lower opening  27   b  towards the bottom dead center of the needles  24 . Each needle hole  27  is tapered such that the diameter at the lower opening  27   b  is less than the diameter at the upper opening  27   a . In this embodiment, the diameter of each upper opening  27   a  is 4.5 mm, and the diameter of each lower opening  27   b  is 3.5 mm.  
     [0068] As shown in FIG. 2, the holding plate  22  includes a pair of front and rear aluminum guiding plates  41  and an elongated coupler plate  43 . A cross-section of each guiding plate  41  along a direction perpendicular to the longitudinal direction of the holding plate  22  is substantially like that of a trough. The coupler plate  43  couples the guiding plates  41  to each other with screws  42 . As shown in FIG. 4, through holes  45  are formed in the bottom (supporting plate portion)  44  of each guiding plate  41 . Each through hole  45  corresponds to one of the needle holes  27  in the needle plate  21 . A fitted member  51  shown in FIG. 5 is fitted to each through hole  45 . Threaded holes  47  for receiving the screws  42  are formed in an upper portion  46  of each guiding plate  41 .  
     [0069] The fitted members  51  are made of steel. Each fitted member  51  includes a cylindrical portion  52  and a flange  53 . The cylindrical portion  52  is press fitted to the corresponding through hole  45  in the bottom  44  of the corresponding guiding plate  41  from below. When the cylindrical portion  52  is fitted to the through hole  45 , the flange  53  contacts the lower surface of the bottom  44 . The cylindrical portion  52  of each fitted member  51  has a needle hole  54  to permit the needles  24  to pass through the fitted member  51  along the axial direction.  
     [0070] As shown in FIG. 5, each needle hole  54  is tapered such that its cross-section along a plane containing the axis of the hole  54  (hereinafter, also referred to as a vertical cross-section) narrows toward the lower end, or toward the side at which the flange  53  is formed. That is, each needle hole  54  has an upper opening  54   a  and a lower opening  54   b . The diameter at the lower opening  54   b  is less than the diameter at the upper opening  54   a . In this embodiment, the diameter of each upper opening  54   a  is 5 mm, and the diameter of each lower opening  54   b  is 4 mm.  
     [0071] The holding plate  22  is located above the needle plate  21 . When sewing is performed, the position of the holding plate  22  is adjusted by a holding plate member driving mechanism (not shown) such that the holding plate  22  contacts the upper fabric sheet  15  in the sewing fabric from above. The holding plate  22  cooperates with the needle plate  21  to hold the sewing fabric, which is formed by stacking the upper fabric sheet  15 , the middle fabric sheet  11 , and the lower fabric sheet  14 .  
     [0072] The needles  24  are supported by a needle driving mechanism (not show) located above the holding plate  22 . The positions of the needles  24  correspond to the needle holes  27 ,  54  in the needle plate  21  and the holding plate  22 . The needle driving mechanism reciprocates the needles  24  between the top dead center above the holding plate  22  and the bottom dead center below the needle plate  21 . A thread hole  24   a  is formed at the lower end of each needle  24 . An upper thread  23  from a cheese located in an upper portion of the quilting machine  10  is drawn through the thread hole  24   a.    
     [0073] Rotatable looper shafts  28  are provided below the needle plate  21  (see FIG. 1). The loopers  26  are fixed to the looper shafts  28  so that each looper  26  corresponds to one of the needle holes  27  formed in the needle plate  21 . The looper shafts  28  are rotated back and forth by power of a power source (not shown) in synchronization with vertical movement of the needles  24 . At this time, a blade portion  29  of each looper  26  is moved back and forth along the fabric feeding direction at a position beside the path of the vertical movement of the needle  24 . A thread hole  30  is formed in the blade portion  29  of each looper  26 . A lower thread  25  is drawn through the thread hole  30 .  
     [0074] Spreaders are located below the needle plate  21 . Each spreader corresponds to and located in front of one of the loopers  26 . When the needles  24  start moving downward from the top dead center, penetrating the fabrics  15 ,  11 ,  14 , toward the bottom dead center, each spreader temporarily holds the lower thread  25  extending from the thread hole  30  of the corresponding looper  26  and the upper thread  23  trapped by the blade portion  29  of the looper  26 , and repeats a predetermined closed loop motion.  
     [0075] An operation of the fabric supporting plates (the needle plate  21 , the holding plate  22 ) of the quilting machine  10  according to the first embodiment will now be described.  
     [0076] During sewing, the needles  24 , the loopers  26  and the spreaders cooperate to form various sewing patterns (stitch) such as double chain stitch on the fabric made by stacking the upper fabric sheet  15 , the middle fabric sheet  11 , and the lower fabric sheet  14 . When the needles  24  start being lifted from the bottom dead center and reach a predetermined lifted position, the loop  31  of the upper thread  23  is formed in an area laterally adjacent to each needle  24  (see FIG. 3). The loop  31  is trapped by the blade portion  29  of the corresponding looper  26  as the looper  26  moves forward from a rearmost position. When the needles  24  are moved downward from the top dead center, the spreaders perform closed loop motion. At this time, each lower thread  25  is engaged with and pulled sideways by the corresponding spreader. In this state, the lower thread  25 , the loop of the corresponding upper thread  23 , and the blade portion  29  of the corresponding looper  26  form a triangular space. The corresponding needle  24  is lowered into the triangular space. As a result, the upper thread  23  and the lower thread  25  are interlooped.  
     [0077] When the needles  24  are moved from the top dead center to the bottom dead center (see FIG. 2), the needles  24  are vibrated, for example, due to vibrations generated by the operation of the quilting machine  10 . This can displace the needles  24  from the original vertical paths. However, in this embodiment, the vertical cross-section of the needle hole  54  of each fitted member  51  fitted in the holding plate  22  is tapered downward. Therefore, even if each needle  24  is displaced from the original path when moving from the top dead center to the bottom dead center, the lower end of the needle  24  is guided by the inner surface of the corresponding needle hole  54  and is aligned with the center of the needle hole  54 .  
     [0078] Depending on a selected sewing pattern (stitch pattern), the sewing fabric including the fabrics  15 ,  11 ,  14  are not only moved forward and backward in the fabric feeding direction, but also moved repeatedly by small amounts, for example laterally, in directions intersecting the fabric feeding direction, while being strained. In such a case, when the needles  24  penetrate the sewing fabric and are about to pass through the needle holes  27  of the needle plate  21 , the needles  24  receive small movements from the fabric, which displace the needles  24  from the original position. However, in this embodiment, the vertical cross-section of each needle hole  27 , through which the needle  24  passes through, is tapered downward. Therefore, even if each needle  24  is about to be displaced from the original path immediately after penetrating the fabrics  15 ,  11 ,  14 , the lower end of the needle  24  is guided by the inner surface of the corresponding needle hole  27  and is aligned with the center of the needle hole  27 .  
     [0079] Further, when the lower end of each needle  24  is moved vertically in the vicinity of the bottom dead center below the needle plate  21 , vibrations and displacement of the needle  24  is favorably limited by the lower opening  27   b  of the corresponding needle hole  27 , which has the small 3.5 mm diameter. That is, while moving toward the bottom dead center, the position of each needle  24  relative to the blade portion  29  of the corresponding looper  26  is favorably maintained. The needle  24  is not lowered outside of a triangular space defined by the corresponding lower thread  24 , which is engaged with and pulled laterally by the spreader, and the loop of the upper corresponding upper thread  23 . Also, when each needle  24  is moved from the bottom dead center to the top dead center, its position relative to the blade portion  29  of the corresponding looper  26  is favorably maintained, and the blade portion  29  of the advancing looper  26  is reliably inserted into the loop of the upper thread  23  formed in a laterally adjacent area of the needle  24 .  
     [0080] The sewing fabric supporting plate of the sewing machine according to the first embodiment has the following advantages.  
     [0081] (1) In the needle plate  21  and the holding plate  22  of the first embodiment, the diameters of the lower openings  27   b ,  54   b  of the needle holes  27 ,  54  are less than the diameters of the upper opening  27   a ,  54   a . Thus, when moving in the vicinity of the bottom dead center, the needles  24  are scarcely vibrated or displaced from the original positions. That is, even if small lateral movements are transmitted to the needles  24  from the sewing fabric including the middle fabric sheet  11 , the needles  24  are prevented from vibrated or displaced from the original positions by the lower openings  27   b ,  54   b  of the needle holes  27 ,  54 . Therefore, the upper threads  23  and the lower threads  25  are reliably interlooped, and a desired sewing patter is obtained without stitch skipping.  
     [0082] (2) In the first embodiment, the vertical cross-sectional shapes of the needle holes  27 ,  54  are tapered downward. Therefore, even if the needles  24  are vibrated (displaced form original positions) while being moved from the top dead center to the bottom dead center, the lower end of each needle  24  is guided by the inner surfaces of the needle holes  27 ,  54  and aligned with the centers of the needle holes  27 ,  54 . This prevents the relative positions of each needle  24  and the corresponding looper  26  from being changed. Accordingly, stitch skipping is prevented. In other words, no products will be wasted.  
     [0083] (3) In the first embodiment, the fitted members  51  are fitted to the through holes  45  formed in the holding plate  22 , and the needle hole  54  is formed in each fitted member  51 . Therefore, if any of the fitted members  51 , in which the needle hole  54  is formed, is damaged, only the damaged fitted member  51  needs to be replaced, and the holding plate  22  need not be replaced. This reduces the maintenance cost.  
     [0084] (4) In the first embodiment, the fitted members  51  are made of steel. Therefore, even if any of the needles  24  contacts the inner surface of the needle hole  54  of the corresponding fitted member  51 , the needle hole  54  is not damaged. As a result, the life of the holding plate  22  is extended.  
     [0085] The first embodiment may be modified as follows.  
     [0086] In the first embodiment, the fitted members  51  are fitted to the through holes  45  formed in the holding plate  22 , and the needle hole  54  is formed in each fitted member  51 . However, the fitted members  51  may be omitted, and each through hole  45  may have a tapered vertical cross-section and function as a needle hole.  
     [0087] In the first embodiment, the vertical cross-sections of the needle holes  27  formed in the needle plate  21  and the cross-sections of the needle holes  54  formed in the fitted members  51  are both tapered. However, only either the needle holes  27  or the needle holes  54  may be tapered.  
     [0088] In the first embodiment, the fitted members  51  having the needle holes  54  are fitted to the through holes  45  formed in the holding plate  22 . In addition, through holes may be formed in the needle plate  21 , and fitted members each having tapered vertical cross-section may be fitted to the through holes in the needle plate  21 .  
     [0089] In the first embodiment, the sewing fabric includes the upper fabric sheet  15 , the middle fabric sheet  11 , and the lower fabric sheet  14 . Alternatively, only any two of the fabrics  15 ,  11 ,  14  may be stacked to form the sewing fabric. Further, four or more fabrics may be stacked to form the sewing fabric. Also, the sewing fabric may include only one fabric sheet.  
     [0090] In the first embodiment, the fitted members  51  are made of steel. However, as long as the fitted members  51  are made of a material that has a sufficient hardness and is not damaged by contact with the needle  24 , any material (for example, an aluminum alloy, titanium, a titanium alloy, and ceramics) may be used.  
     [0091] In the first embodiment, the needle plate  21  and the holding plate  22  are made of aluminum. However, the needle plate  21  and the holding plate  22  may be made of an aluminum alloy (for example, Al—Cu alloy, Al—Si alloy, and Al—Mg alloy), titanium, a titanium alloy, or ceramics.  
     [0092] In the first embodiment, the diameter at the lower opening of each needle hole  27  of the needle plate  21  is 3.5 mm and the diameter at the upper opening is 4.5 mm. However, these diameters may be changed as long as the diameter at the upper opening is more than the diameter at the lower opening. Also, the diameter at the lower opening of each needle hole  54  of the holding plate  22  is 4 mm, and the diameter at the upper opening is 5 mm. However, these diameters may be changed as long as the diameter at the upper opening is more than the diameter at the lower opening.  
     [0093] In the first embodiment, the present invention is applied to the needle plate  21  and the holding plate  22  of the quilting machine  10 . However, the present invention may be applied to only one of the needle plate  21  and the holding plate  22 .  
     [0094] In the first embodiment, the present invention is applied to the needle plate  21  and the holding plate  22  of the quilting machine  10 , which is a sewing machine. However, the present invention may be applied to any sewing fabric supporting plate of other types of sewing machines.  
     [0095] A lower thread supply control apparatus of a quilting apparatus according to a second embodiment will now be described with reference to FIGS.  6  to  8 .  
     [0096] In the second embodiment, a plurality of loopers  122  are provided. Each looper  122  includes a looper supporting body  123  and a looper main body, or a blade portion  124 . The looper supporting body  123  is formed as a thick plate. The looper supporting bodies  123  are fixed to a looper shaft  125  extending in a direction along which needles  119  are arranged. The looper shaft  125  is rotated back and forth in a predetermined angle by a driving mechanism (not shown) in synchronization with vertical movement of the needles  119 . Therefore, as the looper shaft  125  is rotated back and forth, the blade portions  124  fixed to the upper surface of the looper supporting body  123  are swung in a predetermined angle range.  
     [0097] Also, as shown in FIG. 6, a base  126  with a flat top is provided rearward of the looper shaft  125  in a lower portion of the quilting machine  110 . The base  126  extends substantially parallel to the looper shaft  125 . A plurality of lower thread bobbins  127 , or lower thread supply sources, are provided on the base  126 . Each lower thread bobbin  127  corresponds to one of the loopers  122 . Each lower thread bobbin  127  is rotated as the corresponding looper  122  is moved back and forth (particularly, when the looper  122  is advanced). Accordingly, a lower thread  128  is supplied to the looper  122 .  
     [0098] As shown in FIG. 6, a plurality of substantially U-shaped lower thread guiding members  130  are fixed the base  126 . Each lower thread guiding member  130  has a pair of front and rear vertical portions  129 . Top and bottom thread holes  131 , which function as lower thread guides, are formed in each vertical portions  129 . The lower thread  128  from each lower thread bobbin  127  are drawn through the top thread holes  131  of the vertical portions  129  of the corresponding thread guiding member  130 . The lower thread  128  contacts and is bent by the inner edges of the thread holes  131  and reaches the corresponding looper  122 , which is diagonally forward and above. The thread holes  131  form lower thread paths.  
     [0099] A bearing  132  is provided at the lower end of the rear vertical portion  129  of each lower thread guiding member  130 . The bearing  132  is made of a metal piece. A lower thread interfering member, which is a pivot arm  133  made of a wire, is provided for each lower thread guiding member  130 . The pivot arm  133  has an L-shaped shaft portion  134  (rotation center) is inserted to and pivotally supported by the bearing  132 . A lower thread engaging portion, which is a helical thread catch  135 , is formed at the distal end of each pivot arm  133 . The thread catch  135  is engaged with the lower thread  128 , which is drawn through the front and rear thread holes  131  between the front and rear vertical portions  129 .  
     [0100] A weight member  136  is attached to each pivot arm  133  at a section that is near the distal end and is closer to the proximal end than the thread catch  135 . The weight member  136  is made of a square metal plate. Therefore, between the vertical portions  129 , the thread catch  135  of the pivot arm  133  pulls the lower thread  128  downward so that the thread is bent in a V-shape. As a result, the lower thread  128  is pressed against the inner wall of the thread hole  131  of the front vertical portion  129 . This applies a moderate tension to the lower thread  128 , which the looper  122  located forward of the lower thread guiding member  130 .  
     [0101] Each pivot arm  133  pivots about the proximal shaft  134 , which is the rotation center, in accordance with the weight of the weight member  136 . The weight member  136  constantly moves toward a lower position at which the weight  136  contacts the base  126 . The lower position is one of end positions of movement and is also referred to as a cut thread detecting position. In the second embodiment, a photosensor (detection means) including a phototransmitter  137  and a photoreceptor  138  is provided on the base  126 . The phototransmitter  137  and the photoreceptor  138  are provided at the left and right end portions of the base  126 , and correspond to the height of the weight member  136  when at the cut thread detection position.  
     [0102] When light such as an infrared ray emitted by the phototransmitter  137  is not received by the photoreceptor, the photoreceptor  138  sends a cut thread detection signal to a controller (control means)  139  provided on the control panel. Therefore, if one of the lower thread  128  is cut and the corresponding pivot arm  133  pivots downward, so that the weight member  136  reaches the cut thread detection position, the weight member  136  blocks light emitted by the phototransmitter  137 .  
     [0103] The controller  139  is connected to a drive circuit  140  of the quilting machine  110 . When receiving a cut thread detection signal from the photoreceptor  138 , the controller  139  sends an operation stopping signal to the drive circuit  140  to stop operation of the quilting machine  110 . If any of the loopers  122  is not used, that is, if any of the loopers  122  draws no lower thread  128 , the corresponding pivot arm  133  is pivoted to a position at which the pivot arm  133  rests against the corresponding rear vertical portion  129 , or to the other one of the end positions of movement. In the second embodiment, the lower thread guiding members  130 , the pivot arms  133 , the photosensor including the phototransmitter  137  and the photoreceptor  138 , and the controller  139  form a lower thread supply control apparatus.  
     [0104] The operation of the lower thread supply control apparatus of the above quilting machine  110  according to the second embodiment will now be described.  
     [0105] When forming stitches on sewing fabric C using the quilting machine  110 , the lower threads  128  from the lower thread bobbins  127  are supplied to the loopers  122  through the thread holes  131  of the lower thread guiding members  130  as shown in FIG. 6. When, in this state, the quilting machine  110  is started, the needles  119  through which upper threads  120  are drawn are moved up and down as shown in FIGS.  8 ( a ) to  8 ( c ). At the same time, the loopers  122  through which the lower threads  128  are drawn are moved back and forth. Accordingly, the upper threads  120  and the lower threads  128  are interlooped, and a desired stitches are formed on the sewing fabric C.  
     [0106] When the needles  119  are lowered below the needle plate  118 , the loop of each upper thread  120  trapped by the blade portion  124  of the corresponding looper  122  and the corresponding lower thread  128  drawn forward from the blade portion  124  are hooked by the corresponding spreader  141 , which performs a predetermined closed loop motion. Then, the upper thread  120  and the lower thread  128  are pulled sideways by a further closed loop motion of the spreader  141 . Subsequently, the loop of the upper thread  120 , the lower thread  128 , and the blade portion  124  form a space S, which is triangular as viewed from above. The corresponding needle  119  is lowered into the triangular space S.  
     [0107] At this time, if the lower thread  128  supplied to the looper  122  from the lower thread bobbin  127  loosens, the triangular space S is distorted and loses an appropriate tension. As a result, the needle  119  is lowered outside the triangular space S, and the upper thread  120  and the lower thread  128  are not interlooped. However, in this embodiment, as shown FIG. 6, each pivot arm  133  is always pivoted downward by the weight of the corresponding weight member  136 , and the corresponding lower thread  128  is engaged with the thread catch  135  between the front and rear vertical portions  129 .  
     [0108] That is, each pivot arm  133  pivots about the shaft portion (rotation center)  134  supported by the bearing  132  such that the thread catch  135  engaged with the lower thread  128  is moved downward along a pivot path that intersects the path of the lower thread  128  between the vertical portions  129 . Therefore, the lower thread  128  is pulled downward between the vertical portions  129  and bent substantially into a V-shape. Accordingly, the lower thread  128  slides on and is pressed against the thread holes  131 . As a result, tension corresponding to the weight of the weight member  136  is applied to the lower thread  128  at the path to the looper  122 . Thus, the triangular space S shown in FIGS.  8 ( a ) to  8 ( c ) is neatly taut.  
     [0109] During sewing, any of the lower thread  128  can be cut between the lower thread bobbin  127  and the looper  122 . For example, as shown in FIG. 7, suppose that the lower thread  128  of one (middle one) of a plurality of loopers  122  (three loopers  122  in FIG. 7) is cut. Then, the pivot arm  133  having the thread catch  135  that has been engaged with the cut lower thread  128  is pivoted to the cut thread detection position by the weight of the weight member  136 . That is, as shown in FIG. 7, the weight member  136  of the pivot arm  133  that has been engaged with the cut lower thread  128  falls and pivots to the cut thread detection position on the base  126 .  
     [0110] Then, light from the phototransmitter  137  to the photoreceptor  138  (represented by an alternate long and short dashed line in FIG. 7) is blocked by the weight member  136  at the cut thread detection member  136 . Then, the photoreceptor  138 , which stops receiving light, sends a cut thread detection signal to the controller  139 . As a result, the controller  139  sends an operation stopping signal to the drive circuit  140  of the quilting machine  110 . Therefore, when the lower thread  128  supplied to any of the loopers  122  is cut, the operation of the quilting machine  110  is stopped, and stitch skipping is prevented.  
     [0111] The lower thread supply control apparatus of the quilting machine  110  according to the second embodiment has the following advantages.  
     [0112] (1) In the second embodiment, each lower thread  128  is drawn from the lower thread bobbin  127  to the looper  122  through the thread holes  131  of the lower thread guiding member  130 , and is pulled downward in a V-shape by the pivot arm  133 . As a result, an appropriate tension is applied to the lower thread  128 . The lower thread  128 , to which an appropriate tension is applied, cooperates with the loop of the corresponding upper thread  120 , and the blade portion  124  of the looper  122  to form a neat triangular space S. This permits the upper thread  120  and a lower thread  128  to be reliably interlooped, and products will not be wasted due to skipped stitches.  
     [0113] (2) In the second embodiment, each pivot arm  133  applies an appropriate tension to the corresponding lower thread  128  supplied to the looper  122 . The thread catch  135  located at the distal end pivots about the proximal shaft portion (rotation center)  134  along a circular path intersecting the lower thread path between the vertical portions  129  of the lower thread guiding member  130 . Therefore, an appropriate tension is applied to the lower thread  128  reaching the looper  122  by a simple structure. Accordingly, the manufacturing costs of the lower thread supply control apparatus are reduced.  
     [0114] (3) In the second embodiment, when any of the lower thread  128  supplied from the lower thread bobbins  127  to the loopers  122  is cut, the corresponding pivot arm  133  pivots downward to the cut thread detection position, so that the weight member  136  blocks light emitted from the phototransmitter  137  to the photoreceptor  138 . At this time, based on a thread cut detection signal from the photoreceptor  138 , the controller  139  sends an operation stopping signal to the drive circuit  140 . Therefore, when any of the lower thread  128  is cut, the quilting machine  110  is prevented from continuously operating. Thus, products will not be wasted due to skipped stitches.  
     [0115] (4) In the second embodiment, each lower thread  128  is supplied to the corresponding looper  122  via a lower thread path. The lower thread  128  is hooked to the thread catch  135  of the pivot arm  133 . The weight member  136  causes the pivot arm  133  to naturally fall and pivot about the proximal shaft portion (rotation center)  134  toward the thread cut detection position. Therefore, the pivot arm  133  is always moved toward one of the ends of movement (the cut thread detection position) without any additional members such as a spring. This further reduces the costs.  
     [0116] (5) In the second embodiment, when any of the lower thread  128  is cut, the cut thread  128  is detected based on the light from the phototransmitter  137  to the photoreceptor  138  being blocked by the corresponding pivot arm  133  (the weight member  136 ). Unlike a detection using a contact type limit switch, a cut thread is detected by a non-contact type detector. Therefore, the photosensor (the phototransmitter  137  and the photoreceptor  138 ) is not broken by collision with the pivot arms  33 , which brings the maintenance costs of the apparatus in line. If contact type detection means such as limit switches is used, each of the looper  122  requires the detection means (sensor). However, in case of non-contact type detection means such as the photosensor of this embodiment, photosensors of a number corresponding to the number of the loopers  122  need not be prepared. Accordingly, the costs are reduced.  
     [0117] The second embodiment may be modified as follows.  
     [0118] In the second embodiment, light emitted from the phototransmitter  137  is normally not blocked by the weight members  136  of the pivot arms  133 . When any of the weight member  136  moves to the cut thread detection position and blocks the light, the corresponding thread  128  is detected to be cut. However, the quilting machine  110  may be constructed such that the light from the photodetector  137  is normally blocked by the weight members  136  of the pivot arm  133 , each of which engages with the corresponding lower thread  128  in the lower thread path. In this case, when the weight members  136  are moved downward toward cut thread detection positions and the light reaches the photoreceptor  138 , the lower threads  128  are detected to be cut.  
     [0119] In the second embodiment, the detection means includes the phototransmitter  137  and the photoreceptor  138 . However, the detection means may include a single phototransmitter-receptor that transmits and receives light.  
     [0120] In the second embodiment, the weight member  136  is located in the vicinity of the thread catch  135  in each pivot arm  133 . However, the weight members  136  may be omitted. In the second embodiment, each pivot arm  133  is pivoted toward one of the ends of movement by the weight of the corresponding weight member  136 . However, the pivot arm  133  may be pivoted by an urging member such as a spring toward the one end of the movement.  
     [0121] In the second embodiment, each thread catch  135  is formed by helically bending the distal portion of the pivot arm  133 . However, the thread catch  135  may be formed with an engaging member such as hook provided at the pivot arm  133 .  
     [0122] In the second embodiment, any of the lower thread  128  is detected to be cut when the corresponding pivot arm  133  moves to the cut thread detection position, and at this time, the quilting machine is stopped. In addition, the existence of the cut lower thread  128  may be notified to a user with sound or light.  
     [0123] In the second embodiment, each pivot arm  133  pivots about the proximal shaft portion  134 . However, the pivot arm  133  may be formed as a spring. In this case, the pivot arm  133  urges itself toward the cut thread detection position.  
     [0124] In the second embodiment, each lower thread  128  is drawn from the corresponding lower thread bobbin  127  and contacts the inner edges of the corresponding thread holes  131 . However, thread  128  may contact the inner edge of one of the corresponding thread holes  131 .  
     [0125] Next, an eccentric mechanism E of a quilting machine  211  according to a third embodiment will be described with reference to FIGS.  9  to  15 .  
     [0126] As shown in FIG. 9, the quilting machine  211  includes feed rollers  213  located an one end and winding rollers  214  located at the other end. Fabric  212  is sent to a product receiving section through the feed rollers  213  and the winding rollers  214 . A sewing section  215  is located between the feed rollers  213  and the winding rollers  214 . The sewing section  215  sews the fabric  212  fed by the feed rollers  213  thereby manufacturing a quilting product.  
     [0127] The sewing section  215  includes a holding plate  216  and a needle plate  217 . The holding plate  216  and the needle plate  217  hold the fabric  212  being sent to the product receiving section from above and below. Above the holding plate  216  is supported a needle supporting frame  219 , which supports needles  218 . The needle supporting frame  219  is moved vertically. A vertically movable slider  220  is provided adjacent to the needle supporting frame  219 . The slider  220  is coupled to the needle supporting frame  219  by a coupler bar  221 .  
     [0128] The upper end of a coupler shaft  222  is rotatably coupled to the slider  220 . A shaft support  224  is provided on a base  223  of the quilting machine  211  below the slider  220 . The eccentric mechanism E is provided between the shaft support  224  and the lower end of the coupler shaft  222 .  
     [0129] In the third embodiment, the needle supporting frame  219 , the slider  220 , the coupler bar  221 , and the coupler shaft  222  form a needle driving mechanism coupled to the eccentric mechanism E.  
     [0130] The eccentric mechanism E will now be described with reference to FIGS.  10  to  15 ( b ). As shown in FIG. 10, the eccentric mechanism E includes an eccentric shaft  225 , an eccentric member  226 , a connecting rod  227 , spacers  228 ,  229 , and a stopper plate  230 . The eccentric shaft  225  is a steel rod rotatably supported by the shaft support  224 . The eccentric shaft  225  is rotated by power of a drive source (not shown).  
     [0131] The eccentric member  226  is made of aluminum. As show in FIGS.  10 ,  11 ( a ), and  11 ( b ), the eccentric member  226  includes a bearing cylindrical portion  231 , a disk shaped flange portion  232 , a circular step portion  233 , an eccentric cylindrical portion  234 , which are integrated along the axes L 1 , L 2  of the bearing cylindrical portion  231  and the eccentric cylindrical portion  234 . The axis L 2  of the eccentric cylindrical portion  234  is displaced from the axis L 1  of the bearing cylindrical portion  231 . The centers of the flange portion  232  and the step portion  233  are aligned with the axis L 2  of the eccentric cylindrical portion  234 .  
     [0132] A through hole  235  is formed in the eccentric member  226 . The through hole  235  extends from the end surface of the bearing cylindrical portion  231  to the end surface of the eccentric cylindrical portion  234 , and receives the eccentric shaft  225 . The axis L 1  of the bearing cylindrical portion  231  corresponds to the rotation axis of the eccentric shaft  225 . A threaded hole  236  is formed in the peripheral wall of the bearing cylindrical portion  231 . A screw (not shown) is threaded to the threaded hole  236  for fixing the eccentric member  226  to the eccentric shaft  225 . Therefore, the eccentric member  226  is fixed to the eccentric shaft  225  by threading a screw to the threaded hole  236 , and integrally rotates with the eccentric shaft  225 .  
     [0133] In this embodiment, the thickness of the flange portion  232  is 5 mm. The diameter of the flange portion  232  is 130 mm. The thickness of the step portion  233  is 5 mm. The diameter of the step portion  233  is 85 mm. The thickness of the eccentric cylindrical portion  234  (the length along the axis L 2 ) is 41 mm. The diameter of the eccentric cylindrical portion  234  is 75 mm. Three threaded holes  237  are formed on the end surface of the eccentric cylindrical portion  234 . The threaded holes  237  are spaced by equal angular intervals and are located on an imaginary circle the center of which coincides with the axis L 2 . A hollow portion  238  having a predetermined shape is formed in the eccentric cylindrical portion  234  in an area where the threaded hole  237  is not formed. The hollow portion  238  is formed to reduce the weight of the eccentric member  226 .  
     [0134] The connecting rod  227  is made of aluminum. As shown in FIGS.  12 ( a ) and  12 ( b ), the connecting rod  227  includes a sliding ring portion  240  and a rod portion  241 . The sliding ring portion  240  is rotatably fitted to the eccentric cylindrical portion  234  of the eccentric member  226  with an annular bearing  239 . The rod portion  241  is coupled to the lower end of the coupler shaft  222 . The outer diameter of the sliding ring portion  240  is the same as that of the flange portion  232  of the eccentric member  226 . The thickness of the sliding ring portion  240  is less than that of the eccentric cylindrical portion  234  (41 mm), and, in this embodiment, 35 mm. A threaded hole  242  is formed in the sidewall of the sliding ring portion  240 . A screw (not shown) is threaded to the threaded hole  242  for fixing the bearing  239 .  
     [0135] The spacers  228 ,  229  include a first spacer  228  (see FIGS.  13 ( a ) and  13 ( b )) and a second spacer  229  (see FIGS.  14  ( a ) and  14  ( b )). The first spacer  228  is fitted about the step portion  233  of the eccentric member  226 . The second spacer  229  is fitted about the eccentric cylindrical portion  234  of the eccentric member  226 . The first spacer  228  is a resin ring, and has a thickness of 5 mm, an inner diameter of 85 mm, and an outer diameter of 130 mm. The second spacer  229  is a resin ring, and has a thickness of 5 mm, an inner diameter of 75 mm, and an outer diameter of 130 mm.  
     [0136] As shown in FIGS.  15 ( a ) and  15 ( b ), the stopper plate  230  is shaped like a disk. The thickness and the outer diameter are the same as those of the spacers  228 ,  229 . A through hole  243  for receiving the eccentric shaft  225  is formed at a position displaced from the center. Three threaded holes  244  are formed in the stopper plate  230 . The threaded holes  244  correspond to the three threaded holes  237  formed in the end surface of the eccentric cylindrical portion  234 .  
     [0137] When assembling the eccentric mechanism E of the quilting machine  211  according to the third embodiment, the first spacer  228  is fitted about the step portion  233  of the eccentric member  226 . In this state, the sliding ring portion  240  of the connecting rod  227  and the second spacer  229  are fitted to the eccentric cylindrical portion  234 . Then, the stopper plate  230  is fixed to the end surface of the eccentric cylindrical portion  234 , so that the eccentric member  226  and the connecting rod  227  are integrated.  
     [0138] At this time, the flange portion  232  of the eccentric member  226  and the stopper plate  230  determines the position of the connecting rod  227  relative to the eccentric cylindrical portion  234 . Thereafter, the rod portion  241  of the connecting rod  227  is coupled to the coupler shaft  222 , and the eccentric shaft  225 , which supported by the base  223 , drawn through the through holes  235 ,  243  of the eccentric member  226  and the stopper plate  230 . Accordingly, the assembly of the eccentric mechanism E is completed.  
     [0139] The operation of the eccentric mechanism E of the above quilting machine  211  will now be described.  
     [0140] When the eccentric shaft  225  is rotated based on power from a power source (not shown), the rotation is transmitted to the eccentric member  226 . The eccentric member  226 , in turn, converts the rotation into closed loop motion (eccentric rotation). That is, in the eccentric cylindrical portion  234  of the eccentric member  226 , the through hole  235 , which receives the eccentric shaft  225 , is displaced from the axis L 2  of the eccentric cylindrical portion  234 . Thus, the eccentric cylindrical portion  234  moves in a closed loop about the rotation axis (the axis L 1  of the bearing cylindrical portion) of the eccentric shaft  225 .  
     [0141] The proximal sliding ring portion  240  of the connecting rod  227  is rotatably fitted to the eccentric cylindrical portion  234  with the bearing  239 . The coupler shaft  222  is coupled to the rod portion  241  of the connecting rod. The closed loop motion is transmitted to the slider  220  through the connecting rod  227  and the coupler shaft  222 . The slider  220  limits movements other than the vertical movement in the closed motion transmitted form the coupler shaft  222 . Therefore, the slider  220  converts the closed loop motion into the vertical linear reciprocation. The linear reciprocation is transmitted to the needle supporting frame  219  of the sewing section  215 . As a result, the needles  218  are vertically reciprocated.  
     [0142] In the third embodiment, among the members forming the eccentric mechanism E, the eccentric member  226  and the connecting rod  227  are made of aluminum, which is lighter than conventionally used steel. Further, in the eccentric member  226 , the hollow portion  238  is formed in the eccentric cylindrical portion  234 . Therefore, when the rotation of the eccentric shaft  225  rotated by the power of the drive source is transmitted to the eccentric member  226 , the light weight of the eccentric member  226  reduces the load applied to the rotation and thus increases the speed of the rotation. Also, when the closed loop motion of the eccentric member  226  is transmitted to the connecting rod  227 , the light weight of the connecting rod  227  reduces the load applied to the rotation and thus increases the speed of the rotation.  
     [0143] If the first spacer  228  is located between the flange portion  232  and the sliding ring portion  240 , and the second spacer  229  is located between the stopper plate  230  and the sliding ring portion  240 , friction and rattling between the eccentric member  226  and the connecting rod  227  are reduced. Also, lubricant such as grease is applied to the bearing  239  between the eccentric cylindrical portion  234  of the eccentric member  226  and the sliding ring portion  240  of the connecting rod  227 , the lubricant is prevented from scattering due to high speed operation of the eccentric mechanism E.  
     [0144] Therefore, the eccentric mechanism E of the quilting machine  211  according to this embodiment has the following advantages.  
     [0145] (1) Among the members forming the eccentric mechanism E, the eccentric member  226  and the connecting rod  227  are made of aluminum. This reduces the weight of the eccentric member  226  and the connecting rod  227 . Therefore, the power load applied to the drive source, which rotates the eccentric member  226  with the eccentric shaft  225 , is reduced. Also, the operation of the eccentric mechanism E, which converts the rotation produced by the drive source into reciprocation, is easily accelerated.  
     [0146] (2) The hollow portion  238  is formed in the eccentric cylindrical portion  234  of the eccentric member  226  to further reduce the weight of the eccentric ember  226 . This further increases the speed of the operation of the eccentric mechanism E.  
     [0147] (3) As the eccentric shaft  225  rotates, the flange portion  232  of the eccentric member  226  and the sliding ring portion  240  of the connecting rod  227  rotate relative to each other. The first spacer  228  is located between the flange portion  232  and the sliding ring portion  240 . Therefore, the spacer  228  reduces the possibility of seizure due to friction between the eccentric member  226  and the connecting rod  227 .  
     [0148] (4) The resin first and second spacers  228 ,  229  are fitted about the eccentric cylindrical portion  234  of the eccentric member  226  such that the spacers  228 ,  229  hold the sliding ring portion  240  fitted about the eccentric cylindrical portion  234  from both sides. Therefore, even if lubricant such as grease is applied to the inner surface of the sliding ring portion  240 , the lubricant is not scattered about by high speed rotation of the eccentric mechanism E.  
     [0149] The third embodiment may be modified as follows.  
     [0150] In the third embodiment, the first and second spacers  228 ,  229  are made of resin. However, the first and second spacers  228 ,  229  may be made of, for example, ceramics.  
     [0151] In the third embodiment, the hollow portion  238  is formed only in the eccentric cylindrical portion  234 . However, a hollow portion may be formed in the bearing cylindrical portion  231 . Alternatively, the hollow portion  238  need not necessarily be formed.  
     [0152] In the third embodiment, among the members forming the eccentric mechanism E, the eccentric ember  226  and the connecting rod  227  are made of aluminum. However, only one of these member may be made of aluminum.  
     [0153] In the third embodiment, aluminum is used as the material for forming the eccentric member  226  and the connecting rod  227  of the eccentric mechanism E. However, an aluminum alloy (for example, an Al—Cu alloy, an Al—Si alloy, or an Al—Mg alloy), titanium, a titanium alloy, or ceramics.  
     [0154] In the third embodiment, the connecting rod  227  is coupled to the mechanism including the needle supporting frame  219 . However, the connecting rod  227  may be connected to a looper driving mechanism (not shown), which includes a looper shaft rotatably provided below the needle plate  217 . Alternatively, the eccentric mechanism E may be coupled to both of the needle driving mechanism and the looper driving mechanism.  
     [0155] A winding section  313  according to a fourth embodiment of the present invention will be described with reference to FIGS.  16 ( a ) to  18 ( b ).  
     [0156] As shown in FIGS.  17 ,  18 ( a ), and  18 ( b ), the winding section  313  includes a pair of support members  321 , a drive roller  322 , a first free roller  323 , and a second free roller  324 . The support members  321  are fixed to a rear portion of the sewing section  16 . The drive roller  322  is supported between the support members  321 .  
     [0157] The rollers  322 ,  323 ,  324  each have a rough surface on a central circumference to increase the sliding resistance applied to the quilting product  17 . The rollers  322 ,  323 ,  324  have shafts  322   a ,  323   a ,  324   a  at both ends, respectively. The shafts  322   a ,  323   a ,  324   a  are used for supporting the rollers  322 ,  323 ,  324 .  
     [0158] Each support member  321  is a steel square plate. The lower end of each support member  321  has a fixing portion  331  at the lower end. The fixing portion  331  is used to fix the support member  331  to the rear end of the sewing section  16  and has an inverted L-shaped vertical cross-section. Slightly above the fixing portion  331  and in a front portion of each support member  321  is formed a hole for supporting a fixing shaft. The fixing shaft supporting holes rotatably support the shafts  322   a  at the ends of the drive roller  322 . The drive roller  322  is rotated by a drive motor (not shown). At each end of the drive roller  322 , a drive pulley  332  is fixed to the shaft  322   a . The drive pulley  332  is located outward to the corresponding support member  321 . The drive pulleys  322  rotate as the drive roller  322  rotates.  
     [0159] A groove  333  that extends diagonally forward is in a rear portion of each support member  321 . The groove  333  extends diagonally from a corner of the substantially square support member  321  to the fixing shaft receiving hole. A steel groove frame  334  having a U-shaped cross-section is fixed to each groove  333 . Each groove frame  334  supports the corresponding pair of the shafts  323   a ,  324   a  of the first and second free rollers  323 ,  324 .  
     [0160] A pair of first bearing blocks  341  are attached to ends of the first free roller  323 . A pair of second bearing blocks  342  are attached to ends of the second free roller  324 . The first and second bearing blocks  341 ,  342  are hollow and each have a substantially square cross-section. The first and second bearing blocks  341 ,  342  are both rectangular prism (cube). A first circular bearing hole (not shown) is formed in the center of the side of each first bearing block  341 . A second circular bearing hole  342   a  is formed in the center of the side of each second bearing block  342 . Each first bearing hole rotatably supports one of the shafts  323   a , and the second bearing hole  342   a  rotatably supports one of the shafts  324   a.    
     [0161] The first and second bearing blocks  341 ,  342  are each detachably engaged with the corresponding groove frame  334 , and are freely moved (forward and backward) along the corresponding groove  333  along a predetermined width.  
     [0162] A first free pulley  343  is proved at each end of the first free roller  323 . A second free pulley  344  is provided at each end of the second free roller  324 . The first and second free pulleys  343 ,  344  are each fixed to the corresponding shafts  323   a ,  324   a  located outward of the first and second bearing blocks  341 ,  342 . The first and second pulleys  343 ,  344  rotate as the first and second free rollers  323 ,  324  rotate. The free pulleys  343 ,  344  are aligned in the back and forth direction.  
     [0163] A substantially rectangular fixing plate  351  is fixed to the open ends of the grooves  333  of the support members  321 . The fixing plate  351  is made of steel. The fixing plate  351  is arranged to laterally couple the support members  321  each other and prevents the first and second free rollers  323 ,  324  from coming off the support members  321 . A square prism shaped engaging projection  352  projects from an front side of each side of the fixing plate  351 . The engaging projections  352  are engaged with the upper openings of the grooves  334  to prevent the shafts  324   a  of the second free rollers  324  (the second bearing blocks  342 ) from coming off the groove frames  334 . Further, a square recess  353  is formed in the center of the front side of each engaging projection  352 . A second urging member, or a coil spring  354 , and a pressing block  355  are fitted in each recess  353  to urge the corresponding second bearing block  342  engaged with the groove frame  334  frontward.  
     [0164] An urging device  362  is connected to an upper portion of each support member  321  with an L-shaped plate  361 , which has an L-shaped cross-section. Each urging device  362  is located outward of the corresponding support member  321  and corresponds to the pulleys  332 ,  343 ,  344 . A rotation pulley  363  is located at the distal end of each urging device  362 . The rotation pulley  363  is rotatably supported by a rotation shaft  363   a  that extends laterally and perpendicular to the support member  321 . Further, an urging member  364  is provided at the proximal portion (front end) of each urging device  362 . The urging member  364  pulls the rotation pulley  363  and urges the pulley  363  frontward. The urging member  364  pulls the rotation pulley  363  with a force that corresponds to a pressure of 5 atmospheres (approximately 0.5 MPa).  
     [0165] As shown in FIGS.  16 ( a ) and  16 ( b ), a timing belt  365  is engaged with the pulleys  332 ,  343 ,  344 , and  363  on each side. Each timing belt  365  is engaged zigzag with the corresponding set of the drive pulley  332 , the first free pulley  343 , the second free pulley  344  along the winding direction of sewn quilting product  17 . From the second free pulley  344 , the timing belt  365  extends to the drive pulley  332  via the rotation pulley  363 . The pulleys  332 ,  343 ,  344 ,  363  are rotated simultaneously by means of the timing belt  365 .  
     [0166] The operation of the above described quilting machine will now be described.  
     [0167] As shown in FIGS.  16 ( a ) and  16 ( b ), in the winding section  313  of the quilting machine  10 , the bearing blocks  341 ,  342  of the first and second free rollers  323 ,  324  are movable in the range defined by the groove frames  334 , the fixing plate  351 , and the engaging projections  352 . Therefore, when the quilting product  17  is wound about the rough surfaces of the rollers  322 ,  323 ,  324 , the distances between the rollers  322 ,  323 ,  324  are adjusted according to the thickness of the quilting product  17 . Accordingly, the distances between the pulleys  332 ,  343 ,  344  are adjusted.  
     [0168] Further, since the pulleys  332 ,  343 ,  344  receive a predetermined tension of the urging device  362  through the timing belt  365 , the pulleys  332 ,  343 ,  344  are urged to approach each other. As a result, the quilting product  17  wound about the rollers  322 ,  323 ,  324  is held between the rough surfaces of each adjacent pair of the rollers  322 ,  323  by a force based on the tension. This generates a force to send the quilting product  17  from the sewing section  16  to the product receiving section. On the other hand, the pressing blocks  355  of the engaging projections  352  press the second bearing blocks  342  toward the first bearing blocks  341  due to the force of the coil springs  354 . When the quilting product  17  is relatively thick, the pressing blocks  355  aids the generation of a great sending force applied to the quilting product  17 .  
     [0169] When the quilting machine is operating, the feed rollers  12  and the drive roller  322  in the winding section  313  both rotate, and the fabrics  11 ,  14 ,  15  are sent to the sewing section  16  by the feed rollers  12 . Then, the fabrics  11 ,  14 ,  15  are sewn into the quilting product  17 . The drive roller  322  is rotated in a direction shown by arrows in FIGS.  16 ( a ) and  16 ( b ). Then, the sewn quilting product  17  is moved to the winding section  313  by the sending force generated by the rollers  322 ,  323 ,  324 , and then sent to the product receiving section (not shown).  
     [0170] When the quilting product  17  is thin, the distances between the rollers  322 ,  323 ,  324  (the distances between the pulleys  332 ,  343 ,  344 ) are shortened as shown in FIG. 16( a ). At this time, to maintain the constant tension applied to the timing belt  365 , the rotation pulleys  363  is pulled away from the first free pulleys  343  toward the urging members  364 . When the quilting product  17  is thick, the distances between the rollers  322 ,  323 ,  324  (the distances between the pulleys  332 ,  343 ,  344 ) are extended as shown in FIG. 16( b ). At this time, the rotation pulleys  363  is pulled backward toward the first free pulleys  343 . As a result, regardless of its thickness, the quilting product  17  is always held between each adjacent pair of the rollers  322 ,  323 ,  324  with a constant pressing force when being sent to the product receiving section.  
     [0171] The advantages of the fourth embodiment are as follows.  
     [0172] The winding section  313  of the quilting machine according to the fourth embodiment includes the drive roller  322 , the first free roller  323 , and the second free roller  324 . The drive pulleys  332  are fixed to the shafts  322   a  of the drive roller  322 . The first and second free rollers  323 ,  324  are configured such that the shafts  323   a ,  324   a  move back and forth (in the sending direction of the quilting product  17 ) in relation to the drive roller  322 . Further, the winding section  313  includes the urging device  362 . The urging device  362  has the urging members  364 . The urging members  364  urge the rotation pulleys  363  away from the drive pulleys  332 . In addition, the first and second free pulleys  343 ,  344  are fixed to the shafts  323   a ,  324   a  of the first and second free rollers  323 ,  324 . The timing belts  365  are engaged with the pulleys  332 ,  343 ,  344 , and  362 .  
     [0173] That is, instead of using rotation gears as used in conventional quilting machines, the winding section  313  is configured to rotate the pulleys  332 ,  343 ,  344  with the timing belts  365 . Therefore, in the winding section  313 , unlike the conventional quilting machines, no backlashes and skidding of gears between adjacent pair of rollers occur. The quilting product  17  is therefore stably and smoothly sent out.  
     [0174] Further, a predetermined tension is applied to the timing belts  365  coupling the pulleys  332 ,  343 ,  344  by the urging device  362 , so that timing belts  365  do not sag. Therefore, when rotation of the drive pulleys  332  is transmitted to the free pulleys  343 ,  344 , skidding between the timing belts  365  and the pulleys  332 ,  343 ,  344  is effectively prevented. Accordingly, rotation is reliably transmitted between the pulleys  332 ,  343 ,  344 .  
     [0175] In the winding section  313 , the distances between the pulleys  332 ,  343 ,  344  are changed in accordance with the thickness of the quilting product  17 . At this time, the distances between the pulleys  332 ,  343 ,  344  are not unnecessarily extended. Also, a constant pressing force is always applied to the quilting product  17 . Therefore, regardless of the thickness of the quilting product  17 , winding and sending of the quilting product  17  are smoothly performed.  
     [0176] In the winding section  313  of the quilting machine, the urging device  362  and the timing belts  365  urge the first and second pulleys  343 ,  344  to move toward the drive pulleys  332 . The pulleys  363  of the urging members  362  urge the second free pulleys  344 , which are farthest from the drive pulleys  332 , toward the drive pulleys  332 , or toward the front and lower part of the winding section  313 . Therefore, in the winding section  313 , the second free pulleys  344  press the first free pulleys  343  in the same direction, while narrowing the spaces between the pulleys  332 ,  343 ,  344  so that the spaces are equalized. Thus, the spaces between the pulleys  332 ,  343 ,  344  are automatically optimized to be equal to each other and to correspond to the thickness of the quilting product  17 . This permits the quilting product  17  to be effectively wound and sent out. Further, uneven distribution of pressing force applied to the quilting product  17  by the rollers  322 ,  323 ,  324  is eliminated in the entire winding section  313 .  
     [0177] In the winding section  313  of the quilting machine, the timing belts  365  contacting the pulleys  332 ,  343 ,  344  extend in the winding direction of the quilting product  17 . That is, each timing belt  365  contacts the lower end and the rear end of the corresponding drive pulley  332 , the front end and the upper end of the corresponding first free pulley  343 , and the lower end and the rear end of the second free pulley  344 . Likewise, the quilting product  17  contacts the lower end and the rear end of the drive roller  322 , the front end and the upper end of the first free roller  323 , and the lower end and the rear end of the second free roller  324 . Thus, the path of the quilting product  17  in the winding section  313  coincides with the path of the timing belts  365 . This permits the quilting product  17  to be easily wound and sent out.  
     [0178] The fourth embodiment may be modified as follows.  
     [0179] The pulleys  363  of the urging device  362  may be provided at the lower end of the support members  321 , and between the drive pulleys  332  and the second free pulleys  344 . The rotation pulleys  363  may be pulled downward by the urging members  364 .  
     [0180] The direction in which the urging members  365  pulls the rotation pulleys  363  may coincide with the longitudinal direction of the grooves  333 .  
     [0181] The second urging means, which include the coil springs  354  and the pressing blocks  355 , may be omitted. Even in this case, the urging devices  362  urge the first and second free pulleys  343 ,  344  toward the drive pulleys  332 .  
     [0182] Second urging means, which is an elastic member (such as a coil spring) may be held between each first bearing block  341  and the corresponding second bearing block  342 , which are engaged with one of the groove frames  334 . In this case, the second urging means are formed with the elastic members and the coil springs  354  of the fourth embodiment. Alternatively, a structure (second urging means) that corresponds to the recesses  353 , the coil springs  354 , and the pressing blocks  355  of the above embodiment may be provided at the front end of the second bearing blocks  342  or a the rear end of the first bearing block. In this case, the spaces between the rollers  322 ,  323 ,  324  are further easily maintained equal to each other. Also, unexpected changes of tension applied to the timing belts  365  during operation of the quilting machine  10  are reduced.  
     [0183] Other than the quilting machine of the above embodiment, the winding section  13  may be applied to a sewing machine that sews fabric having a predetermined thickness, such as nonwoven fabric cotton cloth.  
     [0184] Loopers of a quilting machine according to a fifth embodiment of the present invention will now be described with reference to FIGS. 19 and 24. The differences from the preceding embodiments will mainly be discussed.  
     [0185] The sewing section  16  has loopers  422  located below the needle plate  418 . Each looper  422  corresponds to one of needles  419 . As shown in FIGS.  19 ( a ) and  19 ( b ), each looper  422  includes a looper support body  423  and a looper main body  424 . The looper support body  423  is formed as a thick plate, and the looper main body  424  is fixed to the upper side of the looper support body  423 . The looper supporting bodies  423  are fixed to a looper shaft  425  extending in a direction along which the needles  419  are arranged. The looper shaft  425  is rotated back and forth in a predetermined angle by a driving mechanism (not shown) in synchronization with vertical movement of the needles  419 . Thus, as the looper shaft  425  rotates back and forth, the looper main bodies  424  pivot in a predetermined angle range.  
     [0186] The looper main body  424  includes a base portion  426  formed as a block, and a blade portion  427 . The blade portion  427  extends forward from the rear end of the base portion  426  and has a pointed end. The distal end (front end) of the blade portion  427  extends further forward than the front side of the looper support body  423 . A thread hole  429  is formed in the blade portion  427  to draw a lower thread  428 , which is also referred to as a looper thread. The lower thread  428  from a lower thread supplier is drawn out of the front opening of the thread hole  429  and is guided to the needle hole  421  of the needle plate  418 .  
     [0187] As shown in FIGS.  19 ( a ),  20 ( a ), and,  20 ( b ), a first arm  430  and a second arm  431  project forward from the base portion  426 . The first arm  430  functions as a loop formation aiding member. The second arm  431  functions as a needle vibration limiting member. The distal ends (front ends) of the first arm  430  and the second arm  431  extend frontward. The first arm  430  substantially linearly extends frontward to a position slightly forward of the front end of the blade portion  427 , and is then bent downward substantially at a right angle. When the looper  422  is viewed from the front, the first arm  430  is located diagonally downward left to (in a laterally adjacent area of) the blade portion  427  and is substantially parallel to the blade portion  427 . More specifically, as shown in FIGS.  20 ( a ) and  20 ( b ), the first arm  430  is arranged diagonally to approach the blade portion  427  toward the front end. A loop forming aiding surface  430   a  is formed to the right of (in the other laterally adjacent area of) the bent distal portion of the first arm  430  that faces the blade portion  427 . The loop forming aiding surface  430   a  projects diagonally upward and rightward.  
     [0188] The second arm  431  extends parallel to the first arm  430  and the blade portion  427  to a point further forward of the front end of the first arm  430 , and then bent downward by an obtuse angle. When the looper  422  is viewed from front, the second arm  431  is located diagonally downward right to the blade portion  427 . The second arm  431  is more elevated than the first arm  430 , which is located leftward of the blade portion  427 . More specifically, as shown in FIGS.  20 ( a ) and  20 ( b ), a central portion of the second arm  431  is formed as a round bar. The central portion is slightly bent rightward such that the second arm  431  is separated from the blade portion  427  by a distance that is substantially equal to the diameter of the needle  419 . Since the second arm  431  is formed as a round bar, the left side portion that faces the blade portion  427  is formed as a needle vibration limiting surface  431   a , which is a smooth bulge.  
     [0189] As shown in FIG. 19( b ), a pair of frontward threaded holes  440  are formed in the base portion  426  of the looper main body  424 . A pair of downward support holes  441  are formed in the upper side of the base portion  426 . The support holes  441  receive the proximal portions of the first and second arms  430 ,  431 . Each threaded hole  440  communicates with one of the support holes  441 . Although FIG. 19( b ) only shows one of the support holes  441  that receives the proximal portion of the second arm  431  and the threaded hole  440  connected thereto, the support hole  441  for the first arm  430  and the threaded hole  440  connected thereto are formed in positions toward the front side of the sheet of FIGS.  19 ( a ) and  19 ( b ).  
     [0190] A set-screw  442  is threaded to each threaded hole  440 . The distal end of each set-screw  442  is pressed against a side of the proximal portion of the corresponding arm (the first arm  430  or the second arm  431 ), which is inserted into the support hole  441 . Each set-screw  442  has a groove  442   a , and threaded to one of the threaded holes  440  with a jig such as screw driver. Accordingly, the set-screw presses and fixes the corresponding one of the first and second arms  430 ,  431 . Therefore, if the first and second arms  430 ,  431  are excessively far from or close to the blade portion  427  of the looper  422 , the set-screws  442  in the threaded hole  440  are receded to release the arms  430 ,  431 . Then, the angles of distal ends of the arms  430 ,  431  are fine-tuned so that the relative positions of the arms  430 ,  431  to the blade portion  427  are adjusted.  
     [0191] The operation of each looper  422  of the above quilting machine  10  will now be described.  
     [0192] FIGS.  21 ( a ) and  21 ( b ) show a state immediately before the needle  419 , through which an upper thread  420  is drawn, starts ascending toward the top dead center above the needle plate  418  after reaching the bottom dead center below the needle plate  418 . When the needle  419  is at the bottom dead center, the blade portion  427  of the looper  422  is at a rearmost position (leftward as viewed in FIG. 21( a )) in a series of frontward and backward movements. In this state, the needle  419  applies the greatest tension to the upper thread  420  one end of which is sewn to a sewing fabric C on the needle plate  418 . As shown in FIGS.  21 ( a ) and  21 ( b ), to the right of the needle  419  at the bottom dead center (the other side), the front end of the second arm  431  is located such that the second arm  431  almost slides against the needle  419 . A spreader  432  is located below the needle plate  418 . An engaging recess (not shown) is formed in the distal portion of the spreader  432 . The spreader  432  rotates clockwise in a closed loop when viewed from above such that the path of the distal portion contains a position directly below the needle hole  421 . The spreader  432  is located at the rearmost position, which is farthest from the looper  422 .  
     [0193] When the needle  419  starts ascending from the state shown in FIGS.  21 ( a ) and  21 ( b ), the upper thread  420  drawn through the needle  419  loosens. As a result, a loop  420   a  of the upper thread  420  is formed to the left of the needle  419 . Simultaneously, the blade portion  427  of the looper  422  is advanced, and the distal end (front end) of the blade portion  427  is inserted into the loop  420   a  of the upper thread  420 . That is, the loop  420   a  of the upper thread  420  is trapped by the blade portion  427  of the looper  422 , through which the lower thread is drawn. Thereafter, although the needle  419  further ascends and is inserted into the needle hole  421  of the needle plate  418 , the loop  420   a  of the upper thread  420  continues being trapped by the blade portion  427  of the advancing looper  422 . The spreader  432  advances diagonally forward left from the rearmost position shown in FIGS.  24 ( a ) and  24 ( b ).  
     [0194] When the needle  419  ascends from the bottom dead center, the loop  420   a  of the upper thread  420  is reliably trapped by the blade portion  427  of the looper  422 . Therefore, the first arm  430  and the second arm  431  are effectively related. That is, if the needle  419  is moved vertically at a high speed, the loop  420   a  of the upper thread  420  is not formed to the right to the needle  419  as it originally should be, but formed to the right of the needle  419  as shown in FIG. 22( b ). Further, when penetrating the sewing fabric C on the needle plate  418 , the needle  419  is vibrated (needle vibration) by small movements of the fabric C leftward and rightward. At a position to the left (one side) of the needle  419 , the relative position of the needle  419  to the blade portion  427  is displaced.  
     [0195] However, in the fifth embodiment, when the needle  419  is at the bottom dead center before ascending, the front end of the second arm  431  is located to the right of the needle  419  such that the second arm  431  almost slides against the needle  419 . When the needle  419  is lifted, the second arm  431  is lowered at a position to the right of the needle  419  such that the second arm  431  almost slides along the needle  419 . Therefore, when the loop  420   a  of the upper thread  420  is about to be formed to the right of the needle  419 , the needle vibration limiting surface  431   a , which is a smooth bulge on the second arm  431 , contacts the needle  419  from the right to prevent the formation of the loop  420   a . When the needle  419  is about to be vibrated by small leftward and rightward movements of the sewing fabric C, the second arm  431  constantly contacts the needle  419  from the right to limit the displacement of the needle  419  (needle vibration).  
     [0196] On the other hand, when the loop  420   a  of the upper thread  420  is formed at a position to the left of the needle  419 , not at a position to the right of the needle  419 , if the loop  420   a  is not sufficiently spread out, the loop  420   a  cannot be trapped by the blade portion  427  of the looper  422 . However, in this embodiment, when the needle  419  starts ascending from the bottom dead center and the loop  420   a  of the upper thread  420  starts forming, the front end of the first arm  430  intersects the needle  419 , which is ascending at a position diagonally downward left to the blade portion  427 , prior to that the blade portion  427  intersects the needle  419 . Further, the loop formation aiding surface  430   a , which is a smooth projection projecting diagonally upward right, is formed in the front side of the first arm  430 . Therefore, when the loop  420   a  of the upper thread  420  is not formed at a position to the left of the needle  419 , the loop formation aiding surface  430  of the first arm  430  contacts the loop  420   a  in a lifting manner from a position diagonally downward left and expands the loop  420   a  to an appropriate degree.  
     [0197] Then, when the needle  419  reaches the top dead center, which is above the needle plate  418 , the looper  422 , which is trapping the loop  420   a  of the upper thread  420 , is moved to the most advanced position below the needle plate  418 . Also, the distal end of the spreader  432  passes through a position directly blow the needle hole  421  of the needle plate  418 . Then, the distal end of the spreader  432  (the engaging recess) causes the lower thread  428 , which is drawn out of the thread hole  429  of the blade portion  427  of the looper  422 , to be engaged with the loop  420   a  of the upper thread  420 , which is trapped by the blade portion  427 . In this state, due to a further closed loop motion of the spreader  432 , the lower thread  428  and the loop  420   a  of the upper thread  420  are pulled laterally (that is to the left (to one side) in this embodiment). Accordingly, a space that is triangular as viewed from above the blade portion  427  is formed.  
     [0198] Subsequently, when the needle  419  is lowered below the needle plate  418 , the needle  419  is lowered into the space S as shown in FIGS.  24 ( a ) and  24 ( b ). As a result, the upper thread  420  and the lower thread  428  are interlooped. Interlooping refers to passing a loop of a thread through a loop of another thread. At this time, if the descending needle  419  is about to be displaced due to small movements of the fabric (if the needle  419  is about to be vibrated), the needle vibration limiting surface  431   a , which smoothly projects toward the left side of the second arm  431 , guides the needle  419  and limits the displacement (needle vibration). In the state of FIGS.  24 ( a ) and  24 ( b ), the looper  422  is moving backward. In this state, when the needle  419  is lowered into the triangular space S, the loop  420   a  of the upper thread  420  trapped by the blade portion  427  is released. At this time, the spreader  432  releases the lower thread  428  and the looper  420   a  of the upper thread  420 , which have been hooked to the distal end (engaging recess) of the spreader  432 . The spreader  432  then starts receding. Subsequently, the looper  422  returns to the state of FIGS.  21 ( a ) and  21 ( b ).  
     [0199] The looper  422  of the quilting machine  10  according to the fifth embodiment has the following advantages.  
     [0200] (1) In the fifth embodiment, when the needle  419  is moved vertically to the vicinity of the bottom dead center below the needle plate  418 , the blade portion  427  of the looper  422  is moved forward and backward at a position to the left of the needle  419 . At the same time, the second arm  431  functioning as the needle vibration limiting member is moved forward and backward at a position to the right of the needle  419 . The second arm  431  and the blade portion  427  cooperate to hold the needle  419  from both sides.  
     [0201] Therefore, when the needle  419  starts ascending from the bottom dead center, if the loop  420   a  of the upper thread  420  is about to be formed at a position to the right of the needle  419  (the other side), the second arm  431  is located to the right of the needle  419  and pushes the upper thread  420  leftward. Therefore, the loop  420   a  of the upper thread  420  is formed at a position to the left of the needle  419 . Therefore, the blade portion  427  of the looper  422 , which is moving at a position to the left of the needle  419 , reliably traps the loop  420   a  of the upper thread  420 .  
     [0202] When the needle  419  is about to be displaced (needle vibration) due to small lateral repetitive movement of the fabric C on the needle plate  418 , the second arm  431 , which almost slides on the needle  419 , limits the displacement (needle vibration). Therefore, the relative positions of the needle  419  and the blade portion  427  of the looper  422  is maintained. Thus, the loop  420   a  of the upper thread  420  is appropriately trapped by the blade portion  427  at a position to the left of the needle  419 .  
     [0203] When the needle  419  is lowered from the top dead center to the bottom dead center, if the needle  419  is about to be displaced (vibrated) due to small lateral repeated movements of the sewing fabric C, the needle vibration limiting surface  431   a , which is a smooth bulge on the second arm  431 , guides the needle  419  toward the blade portion  427 . Therefore, the needle  419  is properly lowered into the triangular space S formed with the lower thread  428  by the spreader  432 . Accordingly, the upper thread  420  and the lower thread  428  are reliably interlooped.  
     [0204] (2) In the fifth embodiment, the second arm  431 , which functions as a needle vibration limiting member, is located diagonally downward right to the blade portion  427 . Therefore, when the needle  419  ascends at a position to the right of the blade portion  427 , formation of the loop  420   a  of the upper thread  420  is prevented at a position to the right of the bald portion  427  before the blade portion  427  starts looping. Therefore, looping is properly performed at a position to the left of the needle  419 .  
     [0205] (3) In the fifth embodiment, the front end of the second arm  431 , which functions as a needle vibration limiting member, projects further frontward than the front end of the blade portion  427  of the looper  422 . Therefore, when advancing, the second arm  431  reliably limits displacement (vibration) of the needle  419  before the blade portion  427  starts looping.  
     [0206] (4) In the fifth embodiment, the second arm  431 , which functions as a needle vibration limiting member, has the needle vibration limiting surface  431   a . The needle vibration limiting surface  431   a  is located at the left side facing the blade portion  427  of the looper  422  and smoothly projects leftward. Therefore, the second arm  431  reliably guides the descending needle  419 , which is about to be displaced (vibrate), toward the blade portion  427  of the looper  422 . Also, when the loop  420   a  of the upper thread  420  is accidentally being formed at a position to the right of (the other side of) the needle  419 , the second arm  431  pushes the loop  420   a  so that the loop  420   a  is properly formed at a position to the left of the needle  419 .  
     [0207] (5) In the fifth embodiment, the first arm  430  is located diagonally downward left of the blade portion  427  and extends substantially parallel to the blade portion  427 . When the needle  419  starts ascending, the first arm  430  aids the formation of the loop  420   a  of the upper thread  420  that is formed at a position to the left of the needle  419 . That is, the loop formation aiding surface  430   a , which is a smooth bulge, is formed in the right side of the front portion of the first arm  430 , that faces the blade portion  427 . The aiding surface  430   a  contacts the loop  420   a  of the upper thread  420  from below in a lifting manner, thereby expanding the loop. Therefore, the blade portion  427  of the looper  422  reliably traps the loop  420   a  of the upper thread  420  at a position to the left of the needle  419 .  
     [0208] (6) In the fifth embodiment, the first and second arms  430 ,  431  are inserted into the support holes  441  in the proximal portion of the looper main body  424 . The positions of the first and second arms  430 ,  431  relative to the blade portion  427  of the looper  422  are fine tuned by receding the set-screws  442  in the threaded holes  440 .  
     [0209] The fifth embodiment may be modified as follows.  
     [0210] In the fifth embodiment, the looper  422  has the first arm  430 , which functions as a loop formation aiding member. However, the first arm  430  may be omitted.  
     [0211] In the fifth embodiment, the loop formation aiding surface  430   a  is formed at the right side of the bent front portion of the first arm  430 . However, the entire first arm  430  may be formed of a substantially linear round bar, and the circumference of the round bar may be used as a loop formation aiding surface.  
     [0212] In the fifth embodiment, the left side of the second arm  431 , which functions as a needle vibration limiting member, is a smooth bulge. However, as long as the side is spaced from the blade portion  427  by a distance corresponding to the outer diameter of the needle  419 , the side may be an oblique surface or a vertical surface.  
     [0213] In the fifth embodiment, the front portion of the second arm  431 , which functions as a needle vibration limiting member, is bent downward by an obtuse angle. However, the front portion of the second arm  431  may be linearly extended.  
     [0214] In the fifth embodiment, the second arm  431 , which functions as a needle vibration limiting member, is formed of a round bar, and is supported in a cantilever manner such that the front portion of the round bar projects frontward. However, both of the distal end and the proximal end of the round bar may be supported by the proximal portion  426  of the looper main body  424 , and a middle portion of the round bar may be bent to project forward.  
     [0215] In the fifth embodiment, the second arm  431 , which functions as a needle vibration limiting member, extends parallel to the blade portion  427  of the looper  422 . However, the second arm  431  need not be parallel to the blade portion  427 . That is, the shape of the second arm  431  may be different from that of the blade portion  427 . For example, the second arm  431  may be V-shaped or W-shaped.  
     [0216] In the fifth embodiment, the front end of the second arm  431 , which functions as a needle vibration limiting member, protrudes forward of the front end of the blade portion  427  of the looper  422 . However, the front end of the second arm  431  may be aligned with the front end of the blade portion  427 . Also, if the second arm  431  almost slides on the right side of the needle  419  when the needle  419  is moved in the vicinity of the bottom dead center, the front end of the second arm  431  may be located rearward of the front end of the second arm  431 .  
     [0217] In the fifth embodiment, the second arm  431 , which functions as a needle vibration limiting member, is located diagonally downward right to the blade portion  427 . However, the second arm  431  may be located substantially at the same height as the blade portion  427 . The second arm  431  may be located diagonally upward right to the blade portion  427 .  
     [0218] In the fifth embodiment, the center portion of the second arm  431 , which functions as a needle vibration limiting member, is formed of a round bar, and the center portion is slightly bent rightward. However, as long as the center portion is spaced from the blade portion  427  by a distance corresponding to the outer diameter of the needle  419 , the center portion may be formed of a linear round bar.  
     [0219] The fifth embodiment is applied to the looper  422  of the quilting machine  10 , which is a type of sewing machine. However, the fifth embodiment may be applied to a looper of other types of sewing machine.  
     [0220] A sixth embodiment of the present invention will now be described.  
     [0221] As shown in FIGS.  26 ,  28 ( a ), and  28 ( b ), substantially rectangular spreaders  432  are provided below the needle plate  418 . Each spreader  432  is formed of a steel plate. As shown in FIG. 25( a ), an engaging recess  433  having a predetermined shape is formed at the distal end of each spreader  432 . When sewing is performed, threads  420 ,  428  are hooked to the engaging recess  433 . When making each spreader  432 , a steel plate is pressed and bent into a predetermined shape. Then, the plate is quenched, and the engaging recess  433  to contact the threads  420 ,  428  is formed by elaborately polishing the plate. Each spreader  432  is located below the needle plate  418  and at an intermediate height between the blade portion  427  of the corresponding looper  422  and the needle plate  418 . The engaging recess  433  is moved along a closed loop in a clockwise direction when viewed from above. The path of the closed loop motion contains a position directly below the needle hole  421 .  
     [0222] As shown in FIG. 26, stainless steel sliding plates  534  are provided on the lower side of the needle plate  418 . Each sliding plate  534  is an extended rectangular plate and functions as thread cutting blade moving means. Sliding grooves  535  are formed on the lower side of the needle plate  418 . Each sliding groove  535  extends along the direction in which the needles  419  are arranged and is located at an intermediate position between an adjacent pair of the needle holes  421 . Each sliding groove  535  also extends in a direction along which the sewing fabric C is moved back and forth. Each sliding plate  534  is engaged with one of the sliding grooves  535  (see FIG. 27( a )). Each sliding groove  535  guides movement of the corresponding sliding plate  534 .  
     [0223] As shown in FIGS. 26 and 27( a ), two elongated holes  536  are formed (only one is shown in the drawing) in front and rear end portions of each sliding plate  534 . Each elongated hole  536  extends in a longitudinal direction of the sliding plate  534 . On the other hand, bolts  537  protrude downward from the lower side of front and rear portions, respectively. Each bolt  537  is inserted into one of the elongated holes  536  of the corresponding sliding plate  534  and prevents the sliding plate  534  from falling with its head (washer). This configuration permits each sliding plate  534  to slide in the corresponding sliding groove  535  in a predetermined range along the back-and-forth movement direction of the sewing fabric C.  
     [0224] The sliding plates  534  are coupled to a coupler plate  538  at the rear ends. The coupler plate  538  extends perpendicular to the sliding plate  534 . The coupler plate  538  permits the sliding plates  534  integrally slides on the lower surface of the needle plate  418 . A reciprocation cylinder  539  is fixed to the rear end of the needle plate  418 . The reciprocation cylinder  539  forms thread cutting blade moving means. The reciprocation cylinder  539  is coupled to the sliding plates  534  with the coupler plate  538 , and simultaneously slides the sliding plates  534  in the back-and-forth movement direction of the sewing fabric C.  
     [0225] A stainless steel thread cutter  540 , which has a T-shape, is fixed to the lower side of the center of each sliding plate  534 . As shown in FIGS.  25 ( b ),  25 ( c ), and  26 , each thread cutter  540  includes a central rectangular fixing portion  541 , and a pair of thread cutting blades  542  extending laterally from the rear section of the fixing portion  541 . A pair of front and rear fixing holes  543  are formed in the center of the fixing portion  541 . A fixing bolt  544  is inserted into the fixing hole  543 . The fixing bolt  544  fixes the thread cutter  540  to the corresponding sliding plate  534 . The proximal portion of the thread cutting blade  542  is bent into a predetermined shape such that the cutting blade  542  is located lower than the fixing portion  541  and extends in a horizontal plane parallel to the fixing portion  541 . An edge  545  for cutting the upper thread  420  is provided at the front side of the outer portion of each blade  542 .  
     [0226] As shown in FIGS.  27 ( b ),  28 ( a ), and  28 ( b ), when the needles  419  are at the top dead center above the needle plate  418 , the blade portion  427  and the spreader  432  of each looper  422  is not aligned with the corresponding needle hole  421 . At this time, a side portion of each blade portion  427  and a side portion of each spreader  432  (a portion at which the engaging recess  433  is not formed) are directly below the opening of the corresponding needle hole  421 . At this time, the engaging recess  433  of each spreader  432  is located in the vicinity of the corresponding needle hole  421  and is engaged with the corresponding upper thread  420 , which is drawn from the needle hole  421  and hooked to the blade portion  427 .  
     [0227] Further, as shown in FIGS.  27 ( b ) and  28 ( a ), each thread cutting blade  542  is located between the blade portion  427  and the spreader  432 . Specifically, the thread cutting blade  542  is located away from the corresponding needle hole  421 , one side (rear side) of the corresponding blade portion  427 , and one side (rear side) of the spreader  432 . Further, as shown in FIG. 28( b ), the outer end of each thread cutting blade  542  is located in the loop  420   a  of the corresponding upper thread  420 , which is drawn from one of the needle holes  421  and is hooked with the blade portion  427 .  
     [0228] The operation of a thread cutting device  546  of the above quilting machine  10  will now be described. The thread cutting device  546  of this embodiment includes a controller for controlling the operation of the reciprocation cylinder  539 .  
     [0229] The needles  419 , the loopers  422 , and the spreaders  432  operate in the same manner as in the fifth embodiment.  
     [0230] On the other hand, when cutting the upper threads  420  with the thread cutting device  546  of this embodiment, cutting of the threads  420  is executed when the needles  419  are at the top dead center above the needle plate  418  as shown in FIGS.  28 ( a ) and  28 ( b ), and the sewing section  16  is not performing sewing. At this time, each thread cutter  540  is at a standby position rearward of the corresponding spreader  432  and the corresponding blade portion  427 . As shown in FIG. 28( b ), the edge  545  of each thread cutter  540  is located directly behind the corresponding loop  420   a , which is hooked at a high tension to the engaging recess  433  of the spreader  432  and the blade portion  427  of the looper  422 .  
     [0231] Then, the controller (not shown) drives the reciprocation cylinder  539 , such that the thread cutters  540  are slid forward from the standby positions to cutting positions shown in FIGS.  29 ( a ) and  29 ( b ). At this time, the loop  420   a  is hooked to the engaging recess  433  of the spreader  432  and the blade portion  427  of the looper  422 . The edge  545  of each thread cutter  540  cuts the corresponding loop  420   a  at a predetermined position. Then, the controller drives the reciprocation cylinder  539  so that the thread cutters  540 , which are at the cutting positions, recede to the standby positions. Thereafter, the controller stops the reciprocation cylinder  539 .  
     [0232] The thread cutting device  546  of the quilting machine according to this embodiment has the following advantages.  
     [0233] In this embodiment, the quilting machine has the thread cutting device  546 . The thread cutting device  546  includes the thread cutting blades  542 , which are moved between the cutting positions between the needle plate  418  and the loopers  422  and the standby positions rearward of the loopers  422 . The thread cutting device  546  is independently formed from the members in the sewing section  16  (for example, the loopers  422  and the spreaders  432 ). Therefore, thread cutting device  546  easily cuts the threads  420  without adversely affecting the sewing operation.  
     [0234] Particularly, since the loopers  422  and the spreaders  432  both oscillate at a high speed, or approximately at 1000 rpm, the loopers  422  and the spreaders  432  are preferably specialized in sewing operation. Thus, in the quilting machine of this embodiment, the sewing section  16 , which exclusively performs sewing, is independent from the thread cutting device  546 , which exclusively perform cutting of the threads  420 . This prevents the sewing section  16  from malfunctioning during sewing. This advantage is particularly remarkable in the quilting machine of this embodiment, which performs high-speed sewing for forming chain stitches.  
     [0235] On the other hand, the loopers of a conventional quilting machines disclosed in the descriptions of U.S. Pat. No. 5,269,238 and No. 5,154,130 each have a blade at a proximal portion for cutting a thread. Also, the retainers of the quilting machines disclosed in these descriptions each have an edge for cutting a thread. These special configurations make the quilting machines costly. Therefore, when the threads need not be cut, loopers having no blades and retainers having no edges are used. When the threads need to be cut, the above described loopers and retainers are used.  
     [0236] In this case, the loopers need to be replaced. However, since there are a great number, for example tens to hundreds, of the loopers, and the position of each looper must be accurate to 0.1 mm, the replacement is extremely troublesome and time-consuming. Unlike these conventional machines, the loopers  422  and the spreader  432  of the quilting machine  10  of this embodiment do not cut threads. The loopers  422  and the spreaders  432  are therefore formed with inexpensive members. Further, these members do not need to be replaced before the useful lives are over. Therefore, quilting products are efficiently produced at a low cost.  
     [0237] The thread cutting device  546  of this embodiment has the thread cutting blades  542 , the thread cutting blade moving device for moving the blades  542  back and forth, and a controller for controlling the thread cutting blade moving device. Further, since the thread cutting blade moving device operated independently operated from the sewing section  16 , the threads  420  are easily cut without adversely affecting the sewing operation. Further, since the thread cutting blade moving device include the sliding plate  534 , the sliding grooves  535 , and the reciprocation cylinder  539 , the above described advantages are obtained with an extremely simple configuration. Also, in the thread cutting device  546 , each thread cutter  540  has a pair of left and right thread cutting blades  542  to cut two different upper threads  420  at a time. This configuration reduces the number of parts.  
     [0238] The sixth embodiment may be modified as follows.  
     [0239] In the sixth embodiment, the thread cutting blades  542  are moved back and forth along the back-and-forth movement direction of the sewing fabric C to cut the upper threads  420 . However, the thread cutting blades  542  may be rotated to cut the upper threads  420 .  
     [0240] In the sixth embodiment, the thread cutting blades  542  are moved back and forth along the back-and-forth movement direction of the sewing fabric C to cut the upper threads  420 . However, each thread cutting blades  542  may be located at a point of intersection of a sliding plate  534  and a straight line connecting a left and right adjacent pair of the needle holes  421  that arranged along the arrangement direction of the needles, and each thread cutting blade  542  may be moved laterally along the arrangement direction of the needles  419  to cut the upper threads  420 .  
     [0241] The sliding grooves  535  formed on the lower surface of the needle plate  418  may be omitted. Even in this case, the elongated holes  536  and the bolts  537  permit the sliding plates  534  to slide in predetermined directions.  
     [0242] When at the cutting position shown in FIG. 29( b ), each thread cutting blade  542  is preferably located close to the upper end of the corresponding blade portion  427 . However, each thread cutting blade  542  must be lower than the upper end of the corresponding blade portion  427 . Further, each thread cutting blade  542  is preferably lower than the height of the midpoint between the lower surface of the needle plate  418  and the upper end of the corresponding blade portion  427 . Further, each thread cutting blade  542  is preferably lower than the height of the midpoint between the lower end of the corresponding spreader  432  and the upper end of the corresponding blade portion  427 . In this case, each thread cutting blade  542  easily cuts the loop  420   a  at one position, which loop  420   a  is hooked to the engaging recess  433  of the corresponding spreader  432  and the blade portion  427  of the corresponding looper  422 .  
     [0243] The thread cutting device  546  may be detachable from the quilting machine  10 . That is, the thread cutting device  546  may include the needle plate  418 , the sliding plates  534  attached to the needle plate  418 , a coupler plate  538  for coupling the sliding plates  534 , the reciprocation cylinder  539  for moving the sliding plates  534  back and forth, the thread cutters  540  each fixed to one of the sliding plates  534 , and the controller for controlling operation of the reciprocation cylinder  539 . As necessary, the sliding grooves  535  are formed in the lower side of the needle plate  418 . Further, attaching means for attaching the needle plate  418  to the sewing section  16  of the quilting machine may be provided. The attaching means may be of any type as long as it is compatible with a structure for maintaining, repairing, or replacing the sewing section of commercially available sewing machines. For example, the attaching means may be, for example, holes for attaching the thread cutting device  546  to a sewing section, and bolts and nuts engaged with the holes to fix the needle plate  418  to the sewing machine. In this case, the thread cutting device  546  is easily attached to a commercially available sewing machine that does not have the thread cutting device  546 . In other words, the structure for cutting thread according to the above embodiment may be applied to a commercially available sewing machine at an extremely low cost. This configuration is useful when replacing the thread cutting device  546  of the quilting machine of the above embodiment.  
     [0244] The thread cutting device  546  is applied to the quilting machine, which is a type of sewing machine that sews fabric with chain stitches. However, the thread cutting device  546  may be applied to a sewing machine that sews fabric through other sewing method, for example, with lock stitches. Alternatively, the thread cutting device  546  may be applied to other types of sewing machines.  
     [0245] Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.