Patent Abstract:
A sewing machine including a needle bar; a sewing needle attached to the lower end of the needle bar; a needle bar drive mechanism vertically driving the needle bar; a presser foot capable of applying releasable pressure on a workpiece cloth and that releases the pressure to allow manual movement and sewing of the workpiece cloth; a regulatory needle including a tip and being capable of assuming a pierced state where the tip is pierced through the workpiece cloth and a non-pierced state, wherein the regulatory needle is moved along with the workpiece cloth while retaining the pierced state of the tip; a regulatory needle drive unit vertically driving the regulatory needle between the pierced state and the non-pierced state in coordination with vertical movement of the sewing needle; and a regulatory needle regulator limiting horizontal movement of the regulatory needle so as not to exceed a predetermined stitch pitch.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application 2008-201861, filed on Aug. 5, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a sewing machine and more particularly to so called free motion sewing machine that forms stitches while manually feeding a workpiece cloth. 
     BACKGROUND 
     Sewing machines have been known which are capable of executing a so called free motion sewing operation. In a free motion sewing operation, a feed dog for longitudinally feeding a workpiece cloth is inactivated within a bed and a presser foot for applying pressure on the workpiece cloth releases its pressure exerted on the workpiece cloth. The user is allowed to manually feed the workpiece cloth freely under such state. The free motion sewing operation will end up in poor looking stitches if the stitches are not formed at a constant stitch pitch. However, forming stitches at a constant stitch pitch through manual feeding of the workpiece cloth has been a difficult task for inexperienced users. 
     To address such difficulties, a sewing machine capable of executing the free motion sewing operation at a constant stitch pitch is proposed, for example, in JP-2002-292175 A hereinafter referred to as patent publication 1. The disclosed sewing machine is provided with a distance measuring element which measures the distance of travel of fed workpiece cloth and a needle speed changing element that changes operating speed of the sewing needle based on the measurement. In another example of a sewing machine disclosed in JP 2008-79998 A hereinafter referred to as patent publication 2, an imaging element and a feed amount regulator are provided. Under the disclosed configuration, the feed amount of workpiece cloth is calculated based on the image data captured by the imaging element. The feed amount regulator compares the calculated feed amount with a predetermined stitch pitch and limits the feed amount based on the comparison. 
     However, the sewing machine disclosed in patent publication 1 requires additional features such as the distance measuring element and the needle speed changing element, whereas the sewing machine disclosed in patent publication 2 requires additional features such as the imaging element and the feed amount regulator. Both sewing machines disadvantageously require complicated configurations. 
     SUMMARY 
     One object of the present disclosure is to provide a sewing machine that allows even inexperienced users to form stitches at a constant stitch pitch in free motion sewing in a simple configuration. 
     In one aspect of the present disclosure there is provided a sewing machine including a needle bar; a sewing needle attached to the lower end of the needle bar; a needle bar drive mechanism that vertically drives the needle bar; a presser foot that is capable of applying releasable pressure on a workpiece cloth and that releases the pressure to allow manual movement and sewing of the workpiece cloth; a regulatory needle that includes a tip and that is capable of assuming a pierced state in which the tip is pierced through the workpiece cloth and a non-pierced state, wherein the regulatory needle is moved along with the workpiece cloth while retaining the pierced state of the tip; a regulatory needle drive unit that vertically drives the regulatory needle between the pierced state and the non-pierced state in coordination with vertical movement of the sewing needle; and a regulatory needle regulator that limits horizontal movement of the regulatory needle in the pierced state so that the horizontal movement does not exceed a predetermined stitch pitch. 
     According to the above described configuration, the tip of the regulatory needle in the pierced state is allowed to move along with the workpiece cloth and the regulatory needle is driven vertically by the regulatory needle drive unit in coordination with the vertical movement of the sewing needle. The regulatory needle regulator limits the horizontal movement of the regulatory needle in the pierced state so that the amount horizontal movement does not exceed a predetermined stitch pitch. Thus, when the user manually transfers the workpiece cloth in free motion, the movement of the workpiece cloth with the regulatory needle in the pierced state does not and is not allowed to exceed the predetermined stitch pitch. The above configuration allows formation of stitches at a constant stitch pitch and even inexperienced users can readily perform free motion sewing at a constant stitch pitch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and advantages of the present disclosure will become clear upon reviewing the following description of the illustrative aspects with reference to the accompanying drawings, in which, 
         FIG. 1  is a front view of a sewing machine according to one exemplary embodiment of the present disclosure with a cover of a sewing machine head removed; 
         FIG. 2  schematically illustrates a mechanical configuration of the sewing machine; 
         FIG. 3  is a partial cross sectional front view of a regulatory needle in an upper position; 
         FIG. 4  is a partial cross sectional front view of a regulatory needle in a lower position; 
         FIG. 5  is a plan view of a needle plate and a bed; 
         FIG. 6  is an enlarged view of the main features of the needle plate and a regulatory plate; 
         FIG. 7  is a cross sectional view taken along line VII-VII of  FIG. 6 ; 
         FIG. 8  is a rear view of the sewing machine with the cover of the sewing machine head removed; 
         FIG. 9A  is a cross sectional view taken along line IX-IX of  FIG. 6  showing a lever in a lowered state; 
         FIG. 9B  is a cross sectional view taken along line IX-IX of  FIG. 6  showing a lever in a lifted state; 
         FIGS. 10A to 10D  schematically illustrate timing in movement of regulatory needle relative to a sewing needle; 
         FIG. 11  is a front view of the main features of a second exemplary embodiment; 
         FIG. 12  is a plan view of a needle guide; and 
         FIGS. 13A and 13B  illustrate partial cross sectional views of cylindrical portions having different inner diameters. 
     
    
    
     DETAILED DESCRIPTION 
     A description will be given hereinafter on exemplary embodiments of the present disclosure. Elements that are substantially identical between the exemplary embodiments are identified with identical reference symbols and their descriptions will not be given if once described. 
       FIGS. 1 to 10  depict a sewing machine according to a first exemplary embodiment. A sewing machine  10  includes a bed  11 , a pillar  12  standing on the right end of bed  11 , an arm  13  extending leftward over bed  11  from the upper end of pillar  12 , and a head  14  defined at the left end of arm  13 . An exterior cover  15  is provided over bed  11 , pillar  12 , arm  13 , and head  14 . 
     Referring now to  FIG. 2 , sewing machine  10  is further provided with a main shaft  16 , a lower shaft  17 , a sewing machine motor  18 , an upper transmission mechanism  19 , a lower transmission mechanism  21 , a needle bar drive mechanism  22 , a needle bar  23 , a sewing needle  24 , a needle plate  25 , and a shuttle  26 . Main shaft  16  extends laterally within arm  13  and is supported rotatably by a bearing not shown. Lower shaft  17  extends laterally within bed  11  and is also supported rotatably by a bearing not shown. Sewing machine motor  18 , upper transmission mechanism  19 , and a lower transmission mechanism  21  are stored within pillar  12 . The rotational drive force generated by sewing machine motor  18  is transmitted to main shaft  16  through a belt  27  provided at upper transmission mechanism  19 , and the rotational drive force of main shaft  16  is in turn transmitted to lower shaft  17  through belt  28  provided at lower transmission mechanism  21 . Rotational drive force of sewing machine motor  18  is thus, transmitted to main shaft  16  through upper rotational transmission mechanism  19 , and from main shaft  16  to lower shaft  17  through lower rotational transmission mechanism  21 . According to the above described configuration, the rotation of sewing machine motor  18  causes the rotation of main shaft  16  and lower shaft  17 . 
     Needle bar drive mechanism  22  is provided on the left end of main shaft  16 . Needle bar  23  is provided within head  14  of sewing machine  10  and its lower end protrudes downward from cover  15  covering head  14 . Needle bar drive mechanism  22  transforms the rotary movement of main shaft  16  into a vertical movement of needle bar  23 . Needle bar  23  is vertically reciprocated once as main shaft  16  is rotated once. Needle bar  23  has a sewing needle  24  detachably attached to its lower end. Bed  11  has needle plate  25  provided in opposition of head  14 . Within bed  11  below needle plate  25 , shuttle  26  comprising a horizontal shuttle composed of an outer shuttle  26  and an inner shuttle  30  is provided. Shuttle  26  receives detachable attachment of bobbin thread bobbin not shown within inner shuttle  30 . Outer shuttle  29  is driven in rotation by lower shaft  17 . On the upper portion of arm  13 , a thread spool attachment  31  is provided to receive a detachable attachment of a thread spool  32  that provides supply of needle thread. Needle plate  25  has a needle hole  33  defined on it for allowing penetration of sewing needle  24  as can be seen in  FIG. 5 . 
     Referring back to  FIG. 1 , head  14  further contains a presser bar  34 . Presser bar  34  is oriented upright relative to needle plate  25  and is vertically movably supported by a sewing machine frame not shown. Presser bar  34  has a presser foot  35  not shown attached to its lower end. Presser foot  35  presses the subject of the sewing operation, which is typically a workpiece cloth not shown, against needle plate  25 . Though not shown in detail, presser foot  35  releases its pressure on the workpiece cloth when sewing in free motion to allow the workpiece cloth to be moved freely by manual transfer. 
     At the lower front face of head  14 , a start/stop switch  36  is provided for starting or stopping a sewing operation. Depression of start/stop switch  36  causes sewing machine motor  18  to be activated or stopped. Other switches and controls such as a back stitch switch  37 , a needle vertically moving switch  38 , a thread cut switch  39 , and a speed adjustment dial  40  are provided on the front faces of head  14  and arm  13 . Back stitch switch  37 , when operated, reverses the cloth feed direction; whereas needle vertically moving switch  38  alternately transfers sewing needle  24  at an upper needle stop position and a lower needle stop position; thread cut switch  39  activates a needle cut mechanism not shown that cuts the needle thread and bobbin thread at the end of a sewing operation; and speed adjustment dial  40  makes adjustments in sewing speed, in other words, the rotational speed of main shaft  16 . 
     At the lower end of head  14 , a regulatory needle  41  which penetrates in an out of the workpiece cloth and a regulatory needle driving element  42  which vertically drives regulatory needle  41  are provided so as to be situated at the left side proximity of sewing needle  24 . Regulatory needle driving element  42  comprises a coil  44  and an electromagnetic actuator  43  provided with a regulatory bar  45 . Regulatory bar  45  retains its upper position shown in  FIG. 3  by a return spring not shown. Coil  44 , when energized, produces electric magnetism that causes regulatory bar  45  to be driven downward against the bias of return spring. Regulatory needle  41  is provided interchangeably at the lower end of regulatory bar  45 . Thus, when coil  44  is de-energized, regulatory needle  41  retains its upper position, whereas when coil  44  is energized, regulatory needle  41  is moved to a lower position shown in  FIG. 4  to penetrate the workpiece cloth. Electromagnetic actuator  43  is supported by a support member  46  which is detachably attached by a fastening screw  47  to a frame  141  secured on the sewing machine frame. Thus, regulatory needle  41  and regulatory needle driving element  42  may be removed from sewing machine  10 , when executing a normal sewing operation, for example. 
     Regulatory needle  41  comprises an elastically deformable spring wire, for example. Regulatory needle  41  has a sharpened tip to allow penetration in and out of workpiece cloth. The base end of regulatory needle  41  is interchangeably secured to regulatory bar  45  of electromagnetic actuator  43 . To elaborate, the base end of regulatory needle  41  is clamped between a holder  48  mounted at the lower end of regulatory bar  45  and clamp member  49  as can be seen in  FIGS. 3 and 4 . Clamp member  49  is screw fastened to holder  48  by a screw not shown and allows replacement of regulatory needle  41  by loosening the fastening screw. 
     Referring now to  FIG. 2 , arm  13  includes a sensor section  51 . Sensor section  51  senses the vertical position of sewing needle  24  through sensing of rotational phase of main shaft  16 . Sensor section  51  comprises a known sensor provided with a plurality of shutters  52 , a photo interrupter  53  and a substrate  54 . Shutters  52  are secured on main shaft  16  and photo interrupter  53  is provided on substrate  54  secured on the sewing machine frame so as to oppose shutters  52 . Though not shown in detail, shutters  52  are each sectoral having a unique angle and provided at different phase positions. The rotational phase of main shaft  16  can be sensed by sensing the unshown edges of shutters  52  by photo interrupter  53 . The vertical position of sewing needle  24  is recognized based on the sensed phase of main shaft  16 . The control circuit not shown, controls the energization and de-energization of coil  44  of electromagnetic actuator  43  based on the incoming electric signals from photo interrupter  53 . 
     Next, a description will be given on a regulatory needle regulator  60  with reference to  FIGS. 3 ,  4 , and  5 . Regulatory needle regulator  60  is provided with a regulatory plate  61  which is fitted into a circular recess  251  defined on needle plate  25  so as to be at level, in other words, coplanar with the upper surface of needle plate  25 . As can be seen in  FIG. 5 , regulatory plate  61  is disc shaped and is provided with a support shaft  62  at its center. As can be seen in  FIGS. 3 ,  4  and  7 , support shaft  62  extends downward from the underside of regulatory plate  61  to penetrate a bearing  611  provided at the lower central portion of circular recess  251 , thereby allowing regulatory plate  61  to rotate about support shaft  62 . Regulatory plate  61  is further provided with six holes  631 ,  632 ,  633 ,  634 ,  635 , and  636  each having a unique inner diameter defined on the circumference centering on the center of support shaft  62  as can be seen in  FIG. 5 . The centers of holes  631  to  636  are disposed at 60 degree angular interval. When regulatory plate  61  assumes the position shown in  FIG. 5 , regulator needle  41  is inserted into hole  633  which is in the closest proximity of needle hole  33 . When the workpiece cloth is manually transferred, the tension between sewing needle  24  and regulatory needle  41  tends to be reduced as the distance between needle hole  33  and hole  633  receiving regulatory needle  41 , that is, the distance between sewing needle  24  and regulatory needle  41  is increased. Reduced tension at the workpiece cloth provides grounds for inconsistent stitch pitch and thus, hole  633  that assumes a position to allow penetration of regulatory needle  41  is moved as close as possible to needle hole  33  receiving sewing needle  24 . 
     Referring now to  FIG. 6 , regulatory plate  61  is further provided with six V-shaped notches  641  to  646  on its outer peripheral portion. Notches  641  to  646  are arranged at 60 degree angular interval. On a portion of the inner wall of circular recess  251  defined on needle plate  25 , a protrusion  252  is formed that protrudes radially inward in V-shape. The selective engagement of protrusion  252  with one of notches  641  to  646  determines the positioning of regulatory plate  61  relative to needle plate  25 . 
     For instance, in  FIG. 6 , shows protrusion  252  being engaged with notch  643 . At this instance, hole  633  is located below regulatory needle  41  such that the center of regulatory needle  41  is coincidental with the center of hole  633 . 
     Next, a description will be given on a hole selector  70  which selects the hole having the desired inner diameter among the six holes  631  to  636 . Referring to  FIG. 7 , hole selector  70  comprises a lever  71  for vertically moving regulatory plate  61 , and support shaft  62 , and a support section  72 . The rear end tip of lever  71  slightly protrudes rearward from the rear side surface of bed  11  as can be seen in  FIGS. 5 ,  7 , and  8  to allow the user to manually operate lever  71  in the vertical direction through this protruding tip. Support section  72  supports the lower end of support shaft  62  so as to be rotatable but axially unmovable. Thus, by lifting lever  71 , the fitting engagement between regulatory plate  61  and circular recess  251  is cancelled to move regulatory plate  61  upward as shown in  FIG. 9B . Thus, engagement of protrusion  252  with one of notches  641  to  646  (notch  643  in  FIG. 6 ) is cancelled to allow rotation of regulatory plate  61  about support shaft  62 . Then, regulatory plate  61  is rotated to locate one of the six holes  631  to  636  that has the desired inner diameter to be located in a position (in the right side relative to support shaft  62 ) as close as possible to needle hole  33  whereafter lever  71  is lowered to lower regulatory plate  61  back into fitting engagement with circular recess  251  as shown in  FIG. 9A . Consequently, protrusion  252  is placed in engagement with one of notches  641  to  646  to determine the rotational positioning of regulatory plate  61 . As described above, the hole through which regulatory needle  41  is inserted is selected from one of the six holes  631  to  636 . 
     Regulatory plate  61  provided on needle plate  25  may be provided on bed  11 , if found appropriate, depending on the size and shape of needle plate  25 . 
     The timing in movement of regulatory needle  41  relative to sewing needle  24  will be described based on  FIG. 10 . Sewing needle  24  and regulatory needle  41  have been illustrated schematically for simplicity of description. Further, workpiece cloth not shown in the previous figures will be represented as workpiece cloth  100 . Description will be given hereinafter with an assumption that regulatory plate  61  assumes a position in which hole  633  has been selected. 
     As can be seen in  FIG. 10A , when sewing needle  24  is pierced through workpiece cloth  100 , workipiece cloth  100  cannot be moved because it is anchored in place by sewing needle  24 , and thus, regulatory needle  41  is displaced upward away from workpiece cloth  100 . When regulatory needle  41  is in the upper position, regulatory needle  41  assumes the initial position residing on a center line L of hole  633 . 
     Then, as can be seen in  FIG. 10B , as sewing needle  24  is elevated, regulatory needle drive unit  42  drives regulatory needle  41  downward so as to pierce workpiece cloth  100  before sewing needle  24  is lifted above workpiece cloth  100 . Regulatory needle  41  is thus, pierced through workpiece cloth  100  by traveling downward below center line L of hole  633 . Under such state, when sewing needle  24  is moved out of workpiece cloth  100 , workpiece cloth  100  is allowed to be moved within the limitation given by regulatory needle  41 . By piercing regulatory needle  41  through workpiece cloth  100  before sewing needle  24  is lifted above workpiece cloth  100 , regulatory needle  41  can takeover the task of limiting the movement of workpiece cloth  100  from sewing needle  24 . 
     Then, as can be seen in  FIG. 10C , by the time sewing needle  24  is lifted out of workpiece cloth  100 , only regulatory needle  41  is pierced through workpiece cloth  100 . Since regulatory needle  41  is made of elastically deformable material, workpiece cloth  100  can be manually moved freely. Even if work piece cloth  100  is moved in the horizontal direction indicated by arrow A in  FIG. 10C , regulatory needle  41  is elastically deformed under the influence of the movement of workpiece cloth  100  to show a bend However, since the tip of regulatory needle  41  is inserted into hole  633 , further movement of regulatory needle  41  can be restricted once the tip of regulatory needle  41  is placed in contact with the inner wall of hole  633 . Thus, workpiece cloth  100  can be moved to the extent of the radius of hole  633 , meaning that the radius of hole  633  defines the stitch pitch. Accordingly, by selecting either of holes  631 ,  632 ,  634 ,  635 , and  636  to replace hole  633 , the distance of movement, in other words, the stitch pitch can be changed. 
     Then, as can be seen in  FIG. 10D , regulatory needle drive unit  42  keeps regulatory needle  41  pierced through workpiece cloth  100  until sewing needle  24  is pierced through workipiece cloth  100 . That is, regulatory needle drive unit  42  moves regulatory needle  41  upward after sewing needle  24  has pierced workpiece cloth  100 . Since movement of workpiece cloth  100  is prohibited by the piercing of sewing needle  24 , workpiece cloth  100  need not be limited in movement by regulatory needle  41 . Regulatory needle  41  being lifted out of workpiece cloth  100  returns, from the bent state, to its original position on center line L of hole  633  by its own elasticity as shown in  FIG. 10A . 
     As described above, regulatory needle  41  stays pierced through workpiece cloth  100  while workpiece cloth  100  is being moved manually. Thus, movement of workpiece cloth  100  can be limited reliably with preciseness. 
     Next, a description will be given on the operation and effect of the first exemplary embodiment. 
     Regulatory needle  41  is made of elastically deformable material and thus, can be moved along with workpiece cloth  100  with the tip of regulatory needle  41  pierced through workpiece cloth  100 . The elastic deformation of regulatory needle  41  is limited by hole  633  of regulatory plate  61 , in other words, workpiece cloth  100  is free to move within the radius of hole  633  meaning that the radius of hole  633  represent the stitch pitch According to the above described configuration, the user is allowed to readily execute free motion sewing with constant stitch pitch by merely moving workpiece cloth  100  such that the tip of regulatory needle  41  contacts the inner wall of hole  633  every time workpiece cloth  100  is manually fed. 
     The above configuration is further advantageous in that stitches with constant stitch pitch can be formed in a simple configuration comprising an elastically deformable regulatory needle  41  and regulatory plate  61  having a hole  633  allowing penetration of regulatory needle  41 . 
     Regulatory plate  61  is disc shaped and is provided with six holes  631  to  636  having unique inner diameters. One of the six holes having the desired inner diameter is selected by rotating regulatory plate  61 . Thus, constant stitch pitch can be obtained in a simple configuration by a simple operation. 
     Further, regulatory needle  41  is provided in the proximity of needle hole  33  allowing penetration of sewing needle  24  and thus, the distance between regulatory needle  41  and sewing needle  24  can be reduced. Such configuration minimizes the slack being produced between the regulatory needle  41  and sewing needle  24  when manually moving workpiece cloth  100  to allow the stitches to be formed precisely in constant stitch pitch. 
     In the first exemplary embodiment, regulatory needle drive unit  42  pierces regulatory needle  41  through workpiece cloth  100  before sewing needle  24  is lifted out of workpiece cloth  100  and stays pierced until sewing needle  24  is pierced through workpiece cloth  100 . Thus, regulatory needle  41  stays pierced through workpiece cloth  100  while workpiece cloth  100  is being manually moved to reliably and precisely prevent movement of workpiece cloth  100  in excess of the predetermined stitch pitch. 
     Further, regulatory needle drive unit  42  is provided with electromagnetic actuator  43  that vertically moves regulatory needle  41 . Thus, regulatory needle  41  can be vertically moved rapidly and precisely in a simple configuration. 
     A description will now be given on a second exemplary embodiment of the present disclosure.  FIG. 11  shows the portion constituting the main features of the sewing machine according to the second exemplary embodiment. 
     As can be seen in  FIG. 11 , the second exemplary embodiment differs from the first exemplary embodiment in the configuration of the regulatory needle regulator, which is identified in the second exemplary embodiment as regulatory needle regulator  160 . Regulatory needle regulator  160  is provided with a needle guide  161  which is provided with a cylindrical section  162  that covers the entire outer periphery of the base end portion of regulatory needle  41 . Regulatory needle  41  comprises an elastically deformable spring wire as was the case in the first exemplary embodiment. The center of cylindrical section  162  is located with the center of regulatory needle  41 . 
     Needle guide  161  is provided integrally with a cylindrical head  163  at its upper end. A portion of the side surface of head  163  defines a planar section  164  shown in  FIG. 12 . Planar section  164  is placed in abutment with the tip of a later described fastening screw  165 . 
     Electromagnetic actuator  43  has holder  48  secured on the lower end of regulatory bar  45  as described earlier. Holder  48  is provided with a fitting hole which establishes fitting engagement with head  163 . Needle guide  161  having its head  163  being fitted into the fitting hole of the holder  48  is fastened unfastenably by fastening screw  165 . Planar section  164  of head  163  is provided to avoid contact with fastening screw  165  which may become an impediment to the detachment of needle guide  161 . 
     Regulatory needle regulator  160  being configured as described above is driven by electromagnetic actuator  43  to move up and down in coordination with the vertical movement of sewing needle  24  as in the first exemplary embodiment. 
     When workpiece cloth  100  is moved with the downwardly driven regulatory needle  41  pierced through it, regulatory needle  41  bends by elastic deformation as work piece cloth  100  is moved. As the lower end of regulatory needle  41  increases the degree of bend, regulatory needle  41  eventually contacts lower end  166  of the inner wall of cylindrical section  162 . Stated differently, the movement of regulatory needle  41  is limited by the inner wall of cylindrical section  162 . This means that the movement of workpiece cloth  100  is limited to half of the inner diameter of cylindrical section  162 , that is, the radius of cylindrical section  162 . When regulatory needle  41  is lifted out of workpiece cloth  100 , it returns to the initial position which is located with the center of cylindrical section  162  by its own elasticity. As described above, half length of the inner diameter, in other words, the radius of cylindrical section  162  represents the stitch pitch. 
     Further, as exemplified in  FIGS. 13A and 13B , different types of needle guide  161  are provided that vary in the inner diameter of cylindrical portion  162 . Thus, the user is allowed to sew in free motion in the desired stitch pitch by selectively attaching needle guide  161  of the desired size. 
     The second exemplary embodiment having the above described configuration provides the following operation and effect. 
     Regulatory needle  41  being elastically deformed by movement of workpiece cloth  100  is limited in movement through contact with the inner wall of cylindrical section  162  of needle guide  161 . Thus, the movement of workpiece cloth in excess of the predetermined stitch pitch can be prohibited by a simple configuration. 
     The present disclosure is not limited to the above described exemplary embodiments but may be modified or expanded as follows. 
     In the first and the second exemplary embodiment, electromagnetic actuator  43  for driving regulatory needle  41  has been provided at head  14  to lower regulatory needle  41  to pierce workpiece cloth  100 . In contrast, electromagnetic actuator  43  may be provided within bed  11  and regulatory needle  41  may be configured to protrude upward through the hole such as hole  633  of regulatory plate  61  to pierce workpiece cloth  100  from the underside. In such case, though not shown in detail, a protective element formed in a cap form, for example, may be provided so as to oppose the protruding regulatory needle  41  for user safety and for preventing workpiece cloth  100  from being lifted by the piercing of regulatory needle  41 . The protective element, however, needs to be provided so as to allow the underlying workpiece cloth  100  to move freely. 
     The count of holes provided on regulatory plate  61  of the first and the second exemplary embodiments is not limited to six, but may be modified as required. 
     Further, support shaft  62  that supports regulatory plate  61  may be eliminated and the disc shaped regulatory plate  61  may be simply fitted into the circular recess  251 . In such case, regulatory plate  61  can be removed by use of tools such as tweezers. 
     While various features have been described in conjunction with the examples outlined above, various alternatives, modifications, variations, and/or improvements of those features and/or examples may be possible. Accordingly, the examples, as set forth above, are intended to be illustrative. Various changes may be made without departing from the broad spirit and scope of the underlying principles.

Technology Classification (CPC): 3