Patent Publication Number: US-9410275-B2

Title: Thread holding mechanism of sewing machine, needle threader thereof, and sewing machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a thread holding mechanism of a sewing machine which reduces the number of thread guiding positions, and which applies a tension to a thread to hold it. Moreover, the present disclosure relates to a needle threader of a sewing machine with the thread holding mechanism, and the sewing machine. 
     2. Description of the Related Art 
     Conventionally, various thread holding mechanisms and needle threaders have been proposed which are for threading a sewing needle of a sewing machine. For example, Japan Patent No. 4139843 discloses a thread holding mechanism of a needle threader which has a supplied thread guided by a thread guide provided at a lower part of a sewing needle, and is further guided by branched thread guides, thereby being held with a tension applied to the held thread. That is, the thread is guided by a total of three positions which are the thread guide and the two branched thread guides. 
     In the needle threader, the thread held by the thread holding mechanism with a tension is drawn from a needle hole by a guide passing through the needle hole. Hence, it is necessary for the thread to maintain a tensioned condition ahead of the needle hole, and according to the conventional technologies, as explained above, a thread holding mechanism that has two thread guiding positions near the needle hole in addition to the thread guide is used. 
     The operation of letting the thread guided at the three thread guiding positions is a bothersome work for a user of the sewing machine. In addition, the thread holding mechanism and the needle threader are disposed near the sewing needle, and thus it is necessary for the user to carry out a thread guiding operation within a narrow space near the sewing needle. Hence, it is difficult for the user to check the hands and to smoothly let the thread guided. 
     Still further, the thread guiding operation within the narrow space may cause the user who touches the sewing needle to be injured, and thus there is a demand for a thread holding mechanism and a needle threader with a higher safeness. 
     The subject matter of the present disclosure has been made in order to address the above-explained technical problems of the conventional technologies, and an objective is to provide a thread holding mechanism of a sewing machine, a needle threader thereof, and the sewing machine which enable a thread guiding operation safely and smoothly, and which can hold the thread with a tension being applied thereto. 
     SUMMARY OF THE INVENTION 
     In order to accomplish the above objective, an aspect of the present disclosure provides a thread holding mechanism of a sewing machine, the thread holding mechanism holding a thread which is supplied from a thread supply source and which is guided by a thread guide. The thread holding mechanism includes: a thread gripper unit that is provided in a movable manner in a vertical direction and that grips an end of the thread guided by the thread guide; and a thread presser unit that is provided between the thread guide and the thread gripper unit, and that is provided so as to maintain a predetermined positional relationship with the thread gripper unit. When the thread gripper unit descends below the thread guide, the thread presser unit abuts the thread. 
     The thread presser unit may have a part abutting the thread provided below a thread gripping position of the thread gripper unit with respect to a horizontal direction. 
     The thread presser unit may include a presser bar that abuts the thread, and the presser bar may have an inclined face formed at a part abutting the thread. 
     The thread gripper unit may be formed with a slit by notching, and the slit may be formed so as to have a width gradually becoming narrower toward an end of the notch. 
     The thread gripper unit may include a tension applier. Moreover, the tension applier may be a leaf spring. 
     In order to accomplish the above objective, another aspect of the present disclosure provides a needle threader of a sewing machine, and the needle threader includes: the thread holding mechanism of the foregoing aspect; a needle bar supporter to which a needle bar that holds a needle with a needle hole is attached; a threader shaft supported in a movable manner in a vertical direction and rotatable; and a threader mechanism that is held by the threader shaft, and that is moved into and out of the needle hole upon rotation of the threader shaft. 
     In order to accomplish the above objective, the other aspect of the present disclosure provides a sewing machine including the thread holding mechanism of the foregoing aspect or the needle threader of foregoing another aspect. 
     According to the subject matter of the present disclosure, it becomes possible to provide a thread holding mechanism of a sewing machine, a needle threader thereof, and the sewing machine which enable a thread guiding operation safely and smoothly, and which can hold the thread with a tension being applied thereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a needle threader with a thread holding mechanism according to an embodiment, and a motor unit that is an actuator of the needle threader; 
         FIG. 2  is a perspective view illustrating the motor unit that actuates the needle threader; 
         FIG. 3  is a front view illustrating the structure of each mechanism of the needle threader; 
         FIG. 4  is a perspective view illustrating the needle threader; 
         FIG. 5  is a front view illustrating the needle threader; 
         FIG. 6  is a back view illustrating the needle threader; 
         FIG. 7  is an exploded perspective view illustrating a needle bar supporter unit of the needle threader; 
         FIG. 8  is an exploded perspective view illustrating a threader shaft unit of the needle threader; 
         FIG. 9  is a perspective view illustrating a thread holding mechanism of the needle threader; 
         FIG. 10  is a front view illustrating the thread holding mechanism of the needle threader; 
         FIG. 11  is a side view illustrating the thread holding mechanism of the needle threader; 
         FIG. 12A  is a perspective view illustrating a leaf spring to be attached to the thread holding mechanism of the needle threader; 
         FIG. 12B  is a side view illustrating the leaf spring to be attached to the thread holding mechanism of the needle threader; 
         FIG. 13A  is a side view illustrating the leaf spring attached to the thread holding mechanism of the needle threader; 
         FIG. 13B  is an enlarged view illustrating a part surrounded by a circle in  FIG. 13A ; 
         FIG. 14  is a perspective view illustrating a threader mechanism of the needle threader; 
         FIG. 15  is a front view illustrating the threader mechanism of the needle threader; 
         FIG. 16  is a side view illustrating the threader mechanism of the needle threader; 
         FIG. 17  is a perspective view illustrating the threader mechanism in a condition in which a thread guiding operation by a user completes; 
         FIG. 18  is a partial enlarged view illustrating a condition in which the thread guiding operation by the user completes; 
         FIG. 19  is a partial enlarged view illustrating a condition in which a thread presser unit abuts a thread; 
         FIG. 20  is a perspective view illustrating the thread holding mechanism and the threader mechanism descended near a needle hole in the needle threader; 
         FIG. 21  A-C are plan views illustrating a needle threading operation by the thread holding mechanism and the threader mechanism in the needle threader; 
         FIG. 22  is a perspective view illustrating the rotating thread holding mechanism and threader mechanism in the needle threader; 
         FIG. 23  is a perspective view illustrating the threader mechanism capturing an thread in the needle threader; and 
         FIG. 24  is a side view illustrating the threader mechanism capturing the thread in the needle threader. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     1. First Embodiment 
     An explanation will be given of an embodiment of the present disclosure applied to a sewing machine. Note that the present disclosure is applicable to various sewing machines, such as a lockstitch sewing machine and a multi-needle sewing machine, and is also applicable to sewing machines available currently and in future. In the following explanation, a direction in which a user is located with respect to a sewing machine will be explained as a front, and a horizontal direction as viewed from the user will be explained as a horizontal direction in some cases. Moreover, a side at which a thread is supplied will be explained as an upper side in some cases. 
     1-1. Structure 
     A detailed explanation will be given of an embodiment of the present disclosure with reference to the accompanying drawings. First, the whole structure of a needle threader A of a sewing machine will be explained with reference to  FIGS. 1 to 3 . As illustrated in  FIG. 1 , the needle threader A is provided with a motor unit B. In this embodiment, the needle threader A will be explained as being actuated by the motor unit B. The actuation mechanism of the needle threader A is not limited to the motor unit B, and other actuation mechanisms are applicable, and, the needle threader A may be actuated by hand. 
     The motor unit B is a mechanism that actuates the needle threader A, and as illustrated in  FIG. 2 , includes a motor B 1 , gears B 2 , and an arm B 3 . The arm B 3  is provided in a movable manner in a vertical direction upon transmission of the rotational motion of the motor B 1  through the gears B 2 . The tip of the arm B 3  is linked with a lever  24  of the needle threader A to be discussed later. The needle threader A has the lever  24  to be discussed later linked with the arm B 3 , thereby performing a needle threading operation in synchronization with the vertical motion of the arm B 3 . 
     The needle threader A performs an operation of threading a needle hole H of a needle N, and as illustrated in  FIG. 3 , includes a needle bar supporter unit A 1 , a threader shaft unit A 2 , a thread holding mechanism A 3 , and a threader mechanism A 4 . The threader shaft unit A 2  is illustrated by dashed line in  FIG. 3 . The structure of each component will be explained in detail with reference to  FIGS. 4 to 16 . 
     (1) Needle Bar Supporter Unit A 1   
     The needle bar supporter unit A 1  holds a needle bar  12  having the needle N attached to the tip. As illustrated in  FIGS. 4 to 7 , the needle bar supporter unit A 1  includes a needle bar supporter  10 . 
     (2) Needle Bar Supporter  10   
     The needle bar supporter  10  supports the needle bar  12 , a threader shaft  20 , and a guide shaft  21  both to be discussed later in a substantially parallel manner. The needle bar supporter  10  is attached to an unillustrated sewing machine frame, and supports the needle bar  12  in a manner operable in the vertical direction and swingable in a direction (horizontal direction) orthogonal to the cloth feeding direction. 
     As illustrated in  FIG. 7 , provided at an upper end side of a side face of the needle bar supporter  10  is an upper needle bar supporting part  10   a . Moreover, provided at a lower end side of the side face of the needle bar supporter  10  at which the upper needle bar supporting part  10   a  is provided is a lower needle bar supporting part  10   b . The upper needle bar supporting part  10   a  is provided with a needle bar supporting hole a 1 . The lower needle bar supporting part  10   b  is provided with a needle bar supporting hole b 1 , a threader shaft supporting hole b 2 , and a guide shaft supporting hole b 3  (illustrated in  FIG. 5 ). The needle bar supporter  10  supports the needle bar  12  through the needle bar supporting hole a 1  and the needle bar supporting hole b 1 . 
     Provided between the upper needle bar supporting part  10   a  of the needle bar supporter  10  and the lower needle bar supporting part  10   b  thereof is a shaft bearing part  10   c  that supports the threader shaft  20  and the guide shaft  21  to be discussed later. The shaft bearing part  10   c  is provided with a threader shaft supporting hole c 2  and a guide shaft supporting hole c 3  (illustrated in  FIG. 6 ). The needle bar supporter  10  supports the threader shaft  20  through the threader shaft supporting hole b 2  and the threader shaft supporting hole c 2 , and supports the guide shaft  21  through the guide shaft supporting hole b 3  and the guide shaft supporting hole c 3 . 
     One end of a spring  11  is attached to a side face of the upper end side of the needle bar supporter  10  opposite to the side face where the upper needle bar supporting part  10   a  is provided. Another end of the spring  11  is attached to the lever  24  of a threader shaft unit A 2  to be discussed later. 
     (b) Needle Bar  12   
     As illustrated in  FIG. 7 , the needle bar  12  is a bar-shape member having a tip attached to the needle N. The needle bar  12  has an upper end side inserted in the needle bar supporting hole a 1  of the upper needle bar supporting part  10   a , and has a lower end side inserted in the needle bar supporting hole b 1  of the lower needle bar supporting part  10   b , and is supported by the needle bar supporter  10  in a manner slidable in the vertical direction. Attached to the needle bar  12  are a needle clamp screw  13  and a pin stopper  14 . 
     The needle clamp screw  13  is to fasten and hold the needle N to the needle bar  12 , and is provided at a tip (lower end) of the needle bar  12 . The needle clamp screw  13  fastens the needle N to the needle bar  12  by screwing in such a way that the needle hole H of the needle N is directed to the sewing direction (back-and-forth direction). Moreover, the needle clamp screw  13  is provided with a thread guide  13   a . A thread supplied from an unillustrated bobbin that is a thread supply source is guided to the thread guide  13   a.    
     The pin stopper  14  restricts the descending position of the thread holding mechanism A 3  and the threader mechanism A 4 . When the thread holding mechanism A 3  and the threader mechanism A 4  reach a position of the needle hole H of the needle N, the pin stopper  14  abuts a pin  23  of the threader shaft  20  to be discussed later. This stops the descending of the threader shaft  20 , the thread holding mechanism A 3  and the threader mechanism A 4 , and causes those to rotate in the circumferential direction of the threader shaft  20 . The pin stopper  14  is attached at a location in the needle bar  12  which allows the thread holding mechanism A 3  and the threader mechanism A 4  to reach the position of the needle hole H upon abutment with the pin  23 . The pin stopper  14  includes a stopper protrusion to stop the pin  23 , and a holding groove that holds the pin  23  with a play (see  FIG. 5 ). 
     (2) Threader Shaft Unit A 2   
     The threader shaft unit A 2  is linked with the thread holding mechanism A 3  and the threader mechanism A 4 , moves those mechanisms in the vertical direction and rotates those mechanisms. The threader shaft unit A 2  is supported by the needle bar supporter  10 . The threader shaft unit A 2  moves in the vertical direction the thread holding mechanism A 3  and the threader mechanism A 4  between a height near the needle clamp screw  13  (standby position) and a height that permits to thread the needle hole H of the needle N (threading position). As illustrated in  FIGS. 4 to 6 and 8 , the threader shaft unit A 2  includes the threader shaft  20 , the guide shaft  21 , and a linking member  22 . 
     (a) Threader Shaft  20   
     The threader shaft  20  is a bar-shape member that is a shaft to allow the thread holding mechanism A 3  and the threader mechanism A 4  to move in the vertical direction and to rotate those mechanisms. As illustrated in  FIG. 6 , the threader shaft  20  has an upper end side inserted in the threader shaft supporting hole c 2  of the shaft bearing part  10   c , and has a lower end side inserted in the threader shaft supporting hole b 2  of the lower needle bar supporting part  10   b , and, is supported by the needle bar supporter  10  in a manner slidable in the vertical direction and rotatable. As illustrated in  FIG. 8 , the pin  23 , the lever  24 , and the spring  25  are attached to the threader shaft  20 . In addition, as illustrated in  FIG. 5 , the thread holding mechanism A 3  and the threader mechanism A 4  are attached to the lower end of the threader shaft  20 . 
     As explained above, the pin  23 , by abutting the pin stopper  14  of the needle bar  12 , stops the threader shaft  20  descending and rotates the threader shaft  20  in the circumferential direction. The pin  23  is provided at the upper end side of the threader shaft  20 . The pin  23  is firmly fastened at the upper end side of the threader shaft  20  in a manner passing all the way through and substantially perpendicular to the lengthwise direction of the threader shaft  20 . The pin  23  is provided in such a way that both ends protrude to the exterior from the diametrical direction of the threader shaft  20 . 
     The lever  24  is linked with the arm B 3  of the motor unit B, and is moved by the vertical motion of the arm B 3 . The lever  24  is provided at the upper end side of the threader shaft  20 . The lever  24  is formed with a hole into which the upper end side of the guide shaft  21  is inserted. The lever  24  is provided with a cam mechanism that rotates the threader shaft  20 . 
     As illustrated in  FIG. 4 , another end of the spring  11  having the one end attached to the needle bar supporter  10  is attached to the lever  24 . Hence, the spring  11  is suspended across the needle bar supporter  10  and the lever  24 , and the thread holding mechanism A 3  and the threader mechanism A 4  linked with the threader shaft unit A 2  are pushed upwardly by the spring elastic force of the spring  11 . 
     A spring  25  pushes the threader shaft  20  upwardly, and is attached to the lower part of the pin  23  in the threader shaft  20 . Below the pin  23 , the spring  25  is attached so as to be located between the shaft bearing part  10   c  of the needle bar supporter  10  and the pin  23 . The spring  25  has a role of pushing the threader shaft  20  upwardly by its elastic force upon abutting with the shaft bearing part  10   c.    
     (b) Guide Shaft  21   
     The guide shaft  21  is a bar-shape member that is a guide to rotate the thread holding mechanism A 3  in the opposite direction to the rotation direction of the threader shaft  20 . As illustrated in  FIG. 6 , the guide shaft  21  has an upper end side inserted in the guide shaft supporting hole c 3  of the shaft bearing part  10   c , has a lower end side inserted in the guide shaft supporting hole b 3  of the lower needle bar supporting part  10   b , and is supported by the needle bar supporter  10  in a manner slidable in the vertical direction and rotatable. The guide shaft  21  has an upper end attached to the lever  24  of the threader shaft  20 , and is moved in the vertical direction and rotated in synchronization with the threader shaft  20 . A guide  21   a  with a guide groove formed at the bottom is attached to the lower end of the guide shaft  21 . The threader shaft  20  is inserted in one end of the guide  21   a . The guide  21   a  is linked with the linking member  22 . 
     (c) Linking Member  22   
     The linking member  22  is to rotate the thread holding mechanism A 3  around the threader shaft  20  in the opposite direction to the rotation direction of the threader shaft  20  in synchronization with the rotation of the threader shaft  20 . The linking member  22  includes a first link plate  22   a  and a second link plate  22   b . A pin protruding from the second link plate  22   b  passes all the way through the hole of the first link plate  22   a , and is fitted in the guide groove of the guide  21   a . The first link plate  22   a  and the second link plate  22   b  are coupled with the thread holding mechanism A 3  and the threader mechanism A 4 , respectively. 
     (3) Thread Holding Mechanism A 3   
     The thread holding mechanism A 3  holds an end side of the thread guided by the thread guide  13   a  of the needle bar  12 . As illustrated in  FIGS. 4 to 6 and 9 to 11 , the thread holding mechanism A 3  includes a thread gripper unit  30  provided in a movable manner in the vertical direction and gripping the end of the thread guided by the thread guide  13   a . As illustrated in  FIG. 9 , the thread gripper unit  30  is formed with a bearing hole  31  and a pin  32 . The thread gripper unit  30  is attached to the lower part of the threader shaft  20  in a rotatable manner upon fastening of the threader shaft  20  with the bearing hole  31 . The thread gripper unit  30  is coupled with the first link plate  22   a  by the pin  32 . In addition, a thread presser unit  33  and a leaf spring  34  are attached to the thread gripper unit  30 . 
     (a) Thread Gripper Unit  30   
     The thread gripper unit  30  grips the end of the thread. As illustrated in  FIG. 4 , the thread gripper unit  30  fastened to the threader shaft  20  has a thread gripper  30   a  bent toward the needle N when the thread holding mechanism A 3  is located at the standby position. As illustrated in  FIG. 11 , the thread gripper  30   a  is formed with a V-shape guide  30   b . A slit  30   c  with a width that enables pinching of the thread is formed in a manner continuous from the guide  30   b  by notching. The thread is inserted in the slit  30   c  in a slid manner, thereby being pinched by the thread gripper unit  30 . The slit  30   c  may be formed so as to make the width narrowed gradually toward the end of the notch and formed as a V-shape slit, thereby holding the thread further firmly. 
     (b) Thread Presser Unit  33   
     The thread presser unit  33  abuts the thread guided by the thread guide  13   a  and the thread gripper unit  30 . The thread presser unit  33  guides the position of the thread upon abutting with the thread, and applies a tension to the thread. That is, when the thread holding mechanism A 3  and the threader mechanism A 4  move from the standby position to the threading position, the thread presser unit  33  abuts the thread, and thus the thread is guided so as to be located ahead of the needle hole H of the needle N. Moreover, the thread presser unit  33  abutting the thread applies a tension in such a way that the thread becomes substantially horizontal ahead of the needle hole H. 
     The thread presser unit  33  is provided so as to maintain a predetermined positional relationship with the thread gripper unit  30 . As illustrated in  FIGS. 9 and 10 , the thread presser unit  33  is formed between the bearing hole  31  and the thread gripper unit  30 . Accordingly, when the thread holding mechanism A 3  is fitted with the threader shaft  20 , the thread presser unit  33  is provided between the thread gripper unit  30  and the thread guide  13   a  that is a thread supply side. 
     The thread presser unit  33  is an L-shape tabular member when viewed from the thread-gripper- 30   a  side and provided substantially parallel with the thread gripper  30   a . That is, the thread presser unit  33  includes a plane to be attached to the thread gripper unit  30 , and a plane orthogonal with the former plane and abuts the thread. Yet, the shape of the thread presser unit  33  is not limited to the L-shape, and a rectangular thread presser unit  33  may have a lower face abutting the thread. 
     The lower face of the thread presser unit  33  may be provided so as to be substantially in parallel with the guide  30   b  of the thread gripper unit  30  which is the thread gripping position. More preferably, as illustrated in  FIGS. 10 and 11 , the lower face of a presser bar  33   a  may be provided so as to be below the position of the guide  30   b  of the thread gripper unit  30 . The thread presser unit  33  is provided so as to maintain the above-explained positional relationship with the thread gripper unit  30 , thereby abutting the thread. 
     The thread presser unit  33  has the presser bar  33   a  formed so as to run from the end of the surface abutting the thread in the horizontal direction. The presser bar  33   a  initially abuts the thread when the thread gripper unit  30  is descended downwardly with respect to the thread guide  13   a . Moreover, the lower face of the presser bar  33   a  is formed as an inclined face inclined downwardly toward the tip. 
     (c) Leaf Spring  34   
     The leaf spring  34  applies a tension to the thread gripped by the thread gripper unit  30 , and is attached to the thread gripper unit  30 . As illustrated in  FIG. 12 , the leaf spring  34  is attached to a face located upwardly between the opposing faces forming the guide  30   b  and the slit  30   c  in the vertical direction. The face located above will be defined as an upper face, while the opposing face located below will be defined as a lower face. 
     As illustrated in  FIG. 13  that is an enlarged view, the leaf spring  34  is attached so as to cover the upper face forming the guide  30   b  and the slit  30   c . The leaf spring  34  may be machined in accordance with the shape of the upper face of the slit  30   c  when the slit  30   c  is formed in a V-shape. The slit  30   c  may be simply a notch, and a V-shape slit  30   c  may be formed by providing an inclined face in the upper face of the leaf spring  34 . 
     The leaf spring  34  is directed downwardly. Hence, when the thread is guided by the slit  30   c , the leaf spring  34  is directed in a direction pushing the thread. This pushing force allows the thread gripped by the thread gripper unit  30  to be further firmly held, and increases the tension of the thread tensioned at the threading position. The member that applies a tension to the thread is not limited to the leaf spring, and an elastic member like a rubber may be utilized. In addition, a tension applying member may be attached to the lower face forming the guide  30   b  and the slit  30   c  to push the thread upwardly. 
     (4) Threader Mechanism A 4   
     The threader mechanism A 4  is to allow the thread guided by the thread guide  13   a  and the thread gripper unit  30  to pass through the needle hole H of the needle N. As illustrated in  FIGS. 4 to 6 , the threader mechanism A 4  and the thread holding mechanism A 3  are provided so as to face with each other with the threader shaft  20  being present therebetween. As will be explained later, the threader mechanism A 4  allows the thread held by the thread holding mechanism A 3  ahead of the needle N to enter the thread hole H from the back of the needle N and to be hooked, thereby allowing the thread to pass through the needle hole H. 
     The threader mechanism A 4  includes a hook holder  40  that couples the threader shaft  20  with the threader mechanism A 4 . As illustrated in  FIGS. 4 and 5 , the hook holder  40  includes a bearing hole  41  and a linking hole  42 . The hook holder  40  is attached to the lower part of the threader shaft  20  in a unified manner so as to rotate in the same direction as the rotation direction of the threader shaft  20  by fastening the threader shaft  20  in the bearing hole  41 . The hook holder  40  is coupled with the second link plate  22   b  through the linking hole  42 . In addition, a threader hook  43  and two guide plates  44  are attached to the hook holder  40 . 
     As illustrated in  FIGS. 14 to 16 , the threader hook  43  hooks up the thread through a hooky part, and allows the thread to pass through the needle hole H. The threader hook  43  is rotated together with the hook holder  40  upon rotation of the threader shaft  20 , and enters the needle hole H of the needle N. The threader hook  43  is formed in a hooky shape having a tip that can enter the needle hole H of the needle N. 
     The guide plates  44  guide the thread in the vertical direction to a position appropriate for the threader hook  43  to capture the thread when the thread is disposed ahead of the needle hole H of the needle N. As illustrated in  FIG. 16 , the guide plates  44  are provided so as to hold the threader hook  43  therebetween, and like the threader hook  43 , are rotated together with the hook holder  40  in accordance with the rotation of the threader shaft  20 . 
     1-2. Operation 
     An explanation will be given of an example needle threading operation of the needle threader A including the thread holding mechanism A 3  as explained above. First, an explanation will be given of a thread guiding operation by the user. The thread guiding operation is carried out with the thread holding mechanism A 3  and the threader mechanism A 4  being located at the standby position. 
     With respect to the thread guided drawn from the bobbin to the proximity of the needle bar  12 , the thread guiding operation carried out by the user of the sewing machine includes the following two procedures: 
     (1) Guide the thread to the thread guide  13   a  of the needle bar  12 . 
     (2) Guide the end side of the thread guided by the thread guide  13   a  to the thread gripper unit  30 . 
     In the above-explained procedure (2), the slit  30   c  of the thread gripper unit  30  is formed in such a way that the width of such a slit becomes narrower toward the end of the notch, and thus the thread is surely held. In addition, the leaf spring  34  pushes downwardly the held thread, thereby increasing the certainty of holding the thread. 
       FIGS. 17 and 18  illustrate the needle threader A having the thread guided by the thread guide  13   a  and the thread gripper unit  30 . As is clear from the partial enlarged view of  FIG. 18 , the thread is guided by only two positions that are the thread guide  13   a  and the thread gripper unit  30 , thus no tension is applied yet. 
     Next, an explanation will be given of a needle threading operation by the needle threader A. The motor B 1  of the motor unit B is actuated and the arm B 3  is descended. In this case, the lever  24  linked with the arm B 3  is moved downwardly against the force by the spring  11  attached to the lever  24 . The lever  24  is also linked with the threader shaft  20  and the guide shaft  21 , and thus the threader shaft  20  and the guide shaft  21  are also descended. 
     The thread holding mechanism A 3  and the threader mechanism A 4  are attached to the threader shaft  20 . Hence, the thread holding mechanism A 3  and the threader mechanism A 4  are also moved downwardly. In this case, as illustrated in  FIG. 19 , when the thread holding mechanism A 3  starts descending, the lower face of the presser bar  33   a  of the thread presser unit  33  located between the thread guide  13   a  and the thread gripper unit  30  abuts the thread guided by the thread guide  13   a  and the thread gripper unit  30 . 
     Hence, the thread presser unit  33  applies a tension to the thread guided by the thread guide  13   a  and the thread gripper unit  30 . When the lower face of the thread presser unit  33  is provided below the thread gripping position of the thread gripper unit  30 , in comparison with a case in which the lower face of the thread presser unit  33  is located at the same height as that of the thread gripping position, a further stronger tension is applied. In addition, since the tip of the presser bar  33   a  is inclined downwardly, the thread is guided to the basal end of the presser bar  33   a  that is the thread pressing position without being detached from the thread presser unit  33 . 
     The lever  24  is further moved downwardly by the motor unit B at a position where the thread holding mechanism A 3  and the threader mechanism A 4  can let the thread to pass through the needle hole H of the needle N. As illustrated in  FIG. 20 , when the thread holding mechanism A 3  is descended to the threading position, the thread guided by the thread guide  13   a  and the thread gripper unit  30  is guided by the thread presser unit  33  so as to be located ahead of the needle hole H of the needle N with a clearance. In addition, the thread is tensioned substantially horizontally by the thread presser unit  33  ahead of the needle hole H, thus maintaining a sufficient tension for the needle threading operation. 
     In the thread supplying path from the unillustrated bobbin, the thread is guided by multiple guides, and thus the thread has a drag at the thread supplying side. Accordingly, when the thread presser unit  33  abuts and pushes the thread guided by the thread guide  13   a  and the thread gripper unit  30 , the thread becomes able to maintain a sufficient tension for the needle threading operation ahead of the needle hole H. Moreover, since the thread guided by the thread gripper unit  30  is pushed downwardly by the leaf spring  34 , a tension is applied to the thread, and thus a tensioned condition of the thread is further surely maintained. 
     When the thread holding mechanism A 3  and the threader mechanism A 4  descend to the threading position, the pin  24  of the threader shaft  20  abuts the stopping protrusion of the pin stopper  14  of the needle bar  12 , thus those mechanisms stop descending. In this condition, when the lever  24  is further moved downwardly, the pin  23  is rotated by the cam mechanism provided at the lever  24 . Hence, the threader shaft  20  is rotated. 
     As illustrated in  FIGS. 21 and 22 , upon rotation of the threader shaft  20 , the threader mechanism A 4  attached to the threader shaft  20  starts rotating, and the thread holding mechanism A 3  also starts rotating. The threader mechanism A 4  has the hook holder  40  rotated in the same direction as the rotation direction of the threader shaft  20 . Upon this rotation, the hook holder  40  is rotated in the forward direction, and thus the threader hook  43  is inserted in the needle hole H of the needle N. 
     The thread holding mechanism A 3  rotates in the opposite direction to the rotation direction of the threader shaft  20  by the linking member  22  that moves along the guide groove of the guide  21   a . Upon this rotation, the thread holding mechanism A 3  is rotated in the backward direction. Hence, the thread guided by the thread guide  13   a  and the thread gripper unit  30  and which has a tension applied to such a thread upon abutting of the thread presser unit  33  is moved ahead of the needle hole H of the needle N. 
     In this case, as illustrated in  FIGS. 22 to 24 , the hooky tip of the threader hook  43  of the threader mechanism A 4  inserted in the needle hole H from the back thereof captures the thread held by the thread holding mechanism A 3  ahead of the needle hole H. At this time, the thread maintaining the tensioned condition by the thread holding mechanism A 3  is guided by the guide plates  44  of the threader mechanism A 4  so as to be located at a position appropriate for the threader hook  43  to capture the thread, i.e., guided so as to be horizontal ahead of the needle hole H. 
     Next, the force by the motor unit B applied to the lever  24  is released, and the threader shaft  20  and the guide shaft  21  are pushed upwardly by the elastic forces by the springs  11  and  25 . In this case, the thread holding mechanism A 3  and the threader mechanism A 4  are moved in the opposite direction when the threader shaft  20  and the guide shaft  21  descend. That is, the threader mechanism A 4  is rotated in the backward direction, and is retracted from the needle hole H with the threader hook  40  capturing the thread, and thus the needle threading operation of the thread with respect to the needle hole H of the needle N is carried out. 
     When the lever  24  is further moved upwardly, the thread holding mechanism A 3  and the threader mechanism A 4  ascend. In this case, while moving upwardly after rotated in the forward direction, the thread holding mechanism A 3  releases the thread from the thread gripper unit  30 . Although the guide  30   b  of the thread gripper unit  30  is firmly holding the thread, the thread has a held direction changed when the thread holding mechanism A 3  is rotated in the forward direction with the thread captured by the threader hook  40 , and becomes likely to be easily released from the guide  30   b . In addition, the guide  30   b  in the V-shape has the width that becomes wider from the end part of the notch to the origin part, and thus the thread is smoothly released when the thread holding mechanism A 3  moves in the direction in which the thread is released. 
     When the lever  24  is moved upwardly, the threader mechanism A 4  is moved upwardly with the threader hook  43  capturing the thread. When the threader hook  43  pulls up the thread, the thread is released from the thread holding mechanism A 3 . Hence, after the completion of the threading with respect to the needle hole H of the needle N, the thread holding mechanism A 3  releases the thread, and thus the length of the thread drawn from the needle hole H becomes long. The needle threading operation by the needle threader A of this embodiment completes as explained above, and the thread holding mechanism A 3  and the threader mechanism A 4  return to the standby position. 
     1-3. Advantageous Effects 
     The advantageous effects of this embodiment employing the above-explained structure are as follows. 
     (1) It is appropriate for the user to guide the thread at the two positions that are the thread guide  13   a  and the thread gripper unit  30 . This enables the user to smoothly carry out a thread guiding operation. 
     (2) Conventional thread holding mechanisms have two thread guiding positions in addition to a thread guide, and thus it is necessary for the user to guide the thread at a total of three positions. In contrast, according to this embodiment, it is appropriate for the user to guide the thread at a total of two positions. Accordingly, a nearby space to the thread gripper unit  30  can be enlarged, which enables the user to safely carry out a thread guiding operation. 
     (3) With respect to the thread guided by the thread guide  13   a  and the thread gripper unit  30 , the thread gripper unit  30  descends below the thread guide  13   a , and the thread presser unit  33  abuts the thread. Hence, even if the thread is guided at only the two positions, the thread is surely pressed by the thread presser unit  33 , and thus the thread can be held in a tensioned condition. 
     (4) When a part of the thread presser unit  33  abutting the thread is provided below the thread gripping position of the thread gripper unit  30 , the tension of the thread can be further increased to ensure the holding. 
     (5) The presser bar  33   a  of the thread presser unit  33  has the inclined face formed at a part abutting the thread. Hence, it becomes possible to guide the thread once abutting the presser bar  33   a  to the basal end of the presser bar  33   a  while preventing the thread from being released from the presser bar  33   a . Accordingly, it becomes possible to further surely hold the thread in a tensioned condition. 
     (6) The guide  30   b  provided in the thread gripper unit  30  is formed in such a way that the width becomes narrower toward the end of the notch. Hence, the thread guided by the user can be surely held, which makes the thread guiding operation further smooth. Moreover, since the guide  30   b  firmly holds the thread, the thread can be held in a further tensioned condition. Furthermore, the guide  30   b  has the width that becomes wider from the end of the notch to the origin part, making the release of the thread smooth. 
     (7) Since the leaf spring  34  is provided at the thread gripper unit  30 , the thread guided by the thread gripper unit  30  can be surely held by the pushing force by the leaf spring  34 . Moreover, the tension of the thread can be enhanced at the needle threading position. 
     (8) The application of the above-explained thread holding mechanism A 3  to the needle threader A makes the thread guiding operation to the needle threader A smooth, and enables the needle threader A to maintain a sufficient tension of the thread for the needle threading operation. Hence, it becomes possible to provide the needle threader A that performs a needle threading operation further surely. 
     (9) When the above-explained thread holding mechanism A 3  or the needle threader A both explained above is applied to a sewing machine, it becomes possible to provide the sewing machine which enables the user to carry out the thread guiding operation safely and smoothly, and which can hold the thread in a tensioned condition. 
     The present disclosure is not limited to the above-explained embodiment, and permits various modifications as needed.