Patent Publication Number: US-7905188-B2

Title: Threading device of sewing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims priority from Japanese Patent Application No. 2007-184444 filed on Jul. 13, 2007 and Japanese Patent Application No. 2008-053411 filed on Mar. 4, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD OF INVENTION 
     The present invention relates to a threading device of a sewing machine which can insert a thread with respect to a plurality of needles, eyes of which being different in height. 
     DESCRIPTION OF RELATED ART 
     In a sewing machine including a plurality of needles, the respective needles have different heights of eyes and are disposed at a regular interval in a direction intersecting a cloth feeding direction. A related art threading device for inserting a thread through each of the needles has a configuration disclosed, for example, in JP 10-137482 A Publication. More specifically, a threading shaft having a lower end provided with a threading hook for inserting a thread into an eye of a needle is supported to enable a vertical motion and a rotating operation with respect to an oscillating base which is oscillatably supported on a sewing machine frame. The threading shaft is provided with a threading lever having a cam groove formed in an oblique direction and enabling an operation downward, a threading guide for determining a height of the threading hook in a threading operation, and a transverse switching cam for oscillating the oscillating base by a manual operation in relation to each other. 
     The threading hook catches an end of a thread on a tip of the threading shaft when the threading shaft is rotated in one direction to insert the thread through the eye of the needle, and the threading shaft is rotated in the other direction to slip out of the eye, thereby pulling the caught thread into the eye to implement a threading operation. 
     A pin to be engaged with the cam groove of the threading lever is protruded from the threading shaft, and furthermore, a guide pin for abutting on an abutting surface of the threading guide is provided in the middle of a downward motion. For this reason, when the threading shaft is moved downward by a downward moving operation of the threading lever, the guide pin abuts on the threading guide in the middle of the downward movement so that the downward movement of the threading shaft is blocked. When the threading lever is operated downward, furthermore, the threading shaft is rotated in the one direction with respect to the threading lever to move the threading hook forward by means of the pin to be engaged with the cam groove. 
     The (two) needles have different arrangements in the direction intersecting the cloth feeding direction and the eyes also have different heights. In the threading device, therefore, two abutting surfaces having different heights are provided on the threading guide and the oscillating base is oscillated by the manual operation of the transverse switching cam to change a position of the threading shaft so that the guide pin is caused to abut on one of the abutting surfaces to enable the threading hook to correspond to the height of the eye and the arrangement of each of the needles. 
     In another related art threading device disclosed in JP 06-49114 B2 Publication, a horizontal shaft is provided on a sewing machine frame close to a vertical moving path of a needle and a threading member having a threading hook on a lower end is supported to be rotatable and oscillatable around the horizontal shaft. There has been known a configuration in which the threading member is moved over an arcuate track in an oblique direction and the threading hook can be inserted into eyes corresponding to positions of two needles. 
     According to the related art threading devices described above, however, a needle with respect to which the threading shaft or the threading member is set cannot be visually checked reliably after a switching operation unless the threading lever or an operation knob is actually operated to carry out a threading operation. For this reason, general users of the sewing machine of this type at home cannot carry out the threading operation at ease so that it is necessary to previously execute the threading operation by way of trial, resulting in a reduction in a working efficiency. 
     In a sewing machine having a large number of needles (e.g., three or more needles), in particular, it is necessary to carry out a work for confirming the needle with respect to which the threading member is set. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a threading device for a sewing machine having a plurality of needles, the threading device being configured to allow a user to easily confirm a needle through which a thread is to be inserted. 
     According to a first aspect of the invention, there is provided a threading device of a sewing machine having a plurality of needles, the threading device being configured to insert a thread through an eye of any one of the needles. 
     The threading device includes: a threading hook which moves forward to enter the eye of one of the needles and moves backward to catch the thread and to insert the thread through the eye; a threading mechanism which moves the threading hook to insert the thread; a selecting portion operable to select, among the plurality of needles, a needle through which the thread is to be inserted; a positioning mechanism which moves the threading hook to a position corresponding to the needle selected by operating the selecting portion; and a selected needle indicating device which distinguishably indicates the needle with respect to which the threading hook has been positioned by operating the selecting portion. 
     According to a second aspect of the invention, the selected needle indicating device includes an indicator which moves together with the threading hook, wherein the selected needle indicating device indicates, in accordance with a position of the indicator, the needle with respect to which the threading hook has been positioned. 
     According to a third aspect of the invention, the selected needle indicating device includes: position detecting means for detecting a position of the threading hook; and display means for indicating the needle corresponding to the position detected by the position detecting means. 
     According to a fourth aspect of the invention, the selected needle indicating device emits light to indicate the needle with respect to which the threading hook has been positioned. 
     According to a fifth aspect of the invention, the selected needle indicating device indicates, at a front side portion of the sewing machine, the needle with respect to which the threading hook has been positioned. 
     According to a sixth aspect of the invention, the selecting portion is disposed on a rear side of an indicating position of the selected needle indicating device. 
     According to a seventh aspect of the invention, there is provided a threading device of a sewing machine having a plurality of needles arranged along a direction intersecting a cloth feeding direction, the threading device being configured to selectively insert a thread through an eye of one of the needles. 
     The threading device includes: a threading hook which is supported on a sewing machine arm so as to be rotatable around a vertical axis and movable along an axial direction of the vertical axis, wherein the threading hook is rotatable, at a downwardly moved position which is coincident with the eye of one of the needles, between a forwardly moved position toward which the threading hook enters the eye and a backwardly moved position toward which the threading hook catches and inserts the thread through the eye; a threading mechanism coupled to the threading hook to rotate the threading hook between the backwardly moved position and the forwardly moved position; a selecting portion operable from an outside of the sewing machine to select a needle through which the thread is to be inserted; a positioning mechanism coupled to the threading hook to move the threading hook, interlockingly with the selecting portion, in the direction along which the plurality of needles are arranged to a position corresponding to the selected needle; and a selected needle indicating device including an indicator which is disposed so as to be visible from the outside of the sewing machine, wherein the indicator is configured to interlock with a movement of the threading hook in the direction along which the plurality of needles are arranged. 
     According to the first aspect of the invention, in a state in which the threading hook is aligned with the corresponding position to the selected needle through the positioning mechanism in accordance with the operation of the selecting portion, the threading hook is rotated and moved forward through the threading mechanism so that the threading operation is executed. 
     At this time, if the threading hook is aligned in accordance with the operation of the selecting portion, the selected needle indicating device indicates the needle with which the threading hook is aligned so as to be distinguishable from the other needles. 
     Differently from the case in which the position of the threading hook is visually confirmed, accordingly, it is possible to accurately grasp the selected needle. Furthermore, it is not necessary to operate the threading hook in order to carry out the confirmation before the threading operation. Therefore, it is possible to eliminate a complicatedness of the confirming work. 
     Also in case of a sewing machine provided with more needles, moreover, it is possible to carry out the confirming work easily and accurately. Consequently, it is possible to properly correspond to a sewing machine having more needles. 
     “The position corresponding to the needle” is a position of the threading hook at which the threading hook can be inserted into the eye of the needle when the threading hook is moved forward. 
     According to the second aspect of the invention, the needle with respect to which the threading hook is positioned is indicated in accordance with the change in the position of the indicator which moves together with the threading hook. Therefore, it is not necessary to provide means for detecting the position of the threading shaft and means for displaying information about the position. Consequently, it is possible to confirm the selected needle with a simple structure. 
     According to the third aspect of the invention, the change in the position of the threading hook is detected and there is provided the display means for indicating the needle based on the detection. Therefore, a mechanical movable structure is not required and a durability can be enhanced without an influence of a deterioration such as an abrasion. 
     According to the fourth aspect of the invention, the needle with respect to which the threading shaft is positioned is indicated with a light emission. Therefore, the selected needle can be distinguished more accurately and immediately. 
     According to the fifth aspect of the invention, the needle with respect to which the threading hook is positioned is indicated on the front side portion of the sewing machine. Therefore, the needle to be selected for the execution of the threading work can be confirmed without moving from a place in which the sewing work is to be carried out or changing a posture to look into the place. Consequently, it is possible to enhance a workability of the threading work and to relieve a burden of an operator. 
     “The front side portion of the sewing machine” is a position to be a front face seen from a position in which the operator is present with respect to the sewing machine in the sewing work, for example, a surface on an upstream side in a feeding direction of a workpiece in a sewing machine frame or a housing cover of the sewing machine. 
     According to the sixth aspect of the invention, the selecting portion is disposed behind the indicating position of the selected needle indicating device. In the operation for selecting the needle to carry out the threading work, therefore, it is possible to avoid a problem that an arm of the operator to carry out the operation causes the indication of the selected needle positioned on the front side of the sewing machine to be shielded or seen with difficulty. Thus, the selection of the needle can be confirmed well and a selecting error can be avoided, and furthermore, a workability can be enhanced. 
     “The rear side the indicating position of the selected needle indicating device” implies a provision on a surface positioned at a downstream side in a cloth feeding direction from a surface over which the selection indication is carried out in the sewing machine frame or the housing cover of the sewing machine. Although it is more desirable to set a position to be a rear face seen from a position in which the operator is present with respect to the sewing machine in the sewing work, it is not restricted but an upper or side surface of the sewing machine frame or the housing cover of the sewing machine may be set. 
     Other aspects and advantages of the invention will be apparent from the following description, the drawings and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a threading device according to a first exemplary embodiment of the invention; 
         FIG. 2  is a front view of the threading device; 
         FIG. 3  is a front view a portion of the threading device; 
         FIG. 4  is a plan view of a portion the threading device; 
         FIG. 5  is an enlarged perspective view showing a lower end portion of a threading shaft; 
         FIG. 6  is a perspective view of the threading device which is seen in a different direction from  FIG. 1 ; 
         FIG. 7  is a rear view a portion of the threading device; 
         FIG. 8  is a side view of a stage switching portion of a selecting portion when seen from a right side; 
         FIG. 9A  is an explanatory view showing an expanded first cam and stage switching positions thereon; 
         FIG. 9B  is an explanatory view showing an expanded second cam and stage switching positions thereon; 
         FIG. 10  is a perspective view of a threading mechanism; 
         FIG. 11  is an explanatory view of a portion of a threading cam mechanism; 
         FIG. 12  is a perspective view of a lower threading guide; 
         FIGS. 13A to 13E  are explanatory views showing a relationship between guide pins and abutting portions in cases in which a threading shaft is positioned so as to correspond to each of the needles through a positioning mechanism; 
         FIG. 14  is an enlarged perspective view of the lower threading guide and an upper threading guide; 
         FIG. 15  is a perspective view showing a mounting position of a selected needle indicating device on a sewing machine; 
         FIG. 16  is a front view of the selected needle indicating device; 
         FIG. 17  is an exploded perspective view of the selected needle indicating device; 
         FIG. 18  is an explanatory plan view showing an operation of the selected needle indicating device; 
         FIG. 19  is a perspective view of a threading device having a selecting portion according to a second exemplary embodiment; 
         FIG. 20  is another perspective view of a portion of the threading device of  FIG. 19 ; 
         FIG. 21  is a rear view of the threading device of  FIG. 19 ; and 
         FIG. 22  is a perspective view showing a mounting position of the threading device of  FIG. 19  on a sewing machine. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. The following exemplary embodiments do not limit the scope of the invention. In the following description, a Z-axis direction is a vertical direction which is parallel to a needle bar  6 , an X-axis direction (a first direction) is a direction intersecting a cloth feeding direction, and a Y-axis direction (a second direction) is a direction parallel to the cloth feeding direction. 
     First Exemplary Embodiment 
     A threading device  10  of a sewing machine according to a first exemplary embodiment will be described with reference to  FIGS. 1 to 18 . 
     The sewing machine mounting the threading device  10  thereon can selectively implement an overlock stitch and a cover stitch and has the needle bar  6  capable of attaching five needles  1 - 5 . Two needles  1  and  2  are used for the overlock stitch and three needles  3 ,  4  and  5  are used for the cover stitch. The needles  1 ,  2  of a first group and the needles  3 ,  4 ,  5  of a second group are parallel with the first direction respectively and are disposed with an offset in a second direction. 
     The threading device  10  is disposed in an arm portion of the sewing machine adjacently to the needle bar  6 . 
     The threading device  10  includes a threading shaft  11  for holding a threading hook  20  to insert, through eyes of the needles  1 - 5 , a thread entering the eyes of the needles by a forward movement and caught by a backward movement, a threading mechanism  300  for giving a back and forth movement to the threading hook  20  through the threading shaft  11 , a thread holding member  50  for holding the thread in an arrangement on an opposite side to the threading hook  20  with the needles  1 - 5  interposed therebetween, a thread holding member support mechanism  60  for movably supporting the thread holding member  50  between a threading position in an arrangement on the opposite side to the threading hook  20  with the needles  1 - 5  interposed therebetween and a standby position separated from the needles  1 - 5 , a first support mechanism  100  for supporting the threading shaft  11  movably in the X-axis direction, a second support mechanism  200  for supporting the threading shaft  11  movably in the Y-axis direction, a positioning mechanism  400  for moving the threading shaft  11  to a corresponding position to a selected one of the needles  1 - 5  by an operation for a selecting dial  401  (a selecting portion), a selected needle indicating device  70  for distinguishably indicating one of the needles  1 - 5  with respect to which the threading shaft  11  is positioned through an operation of the selecting dial  401 , and a main frame  90  for supporting each structure. 
     [Threading Shaft and Threading Hook] 
     In  FIG. 5 , a hook holding arm  21  is fixed to a lower end of the threading shaft  11 . The threading hook  20  supported in a tip part of the hook holding arm  21  has a hook portion formed in a tip part thereof. The hook portion in the tip part of the threading hook  20  can be inserted into any of eyes  1   a - 5   a  of the needles  1 - 5  in a forward movement through a rotation in one direction of the threading shaft  11 , and furthermore, is removed from the eye while catching the thread by the hook portion in a return in a reverse direction to the threading shaft  11 . 
     A pair of guide plates  22 ,  23  is provided in parallel in the tip part of the hook holding arm  21 . The guide plates  22 ,  23  are provided apart from each other so as to enable an insertion of one of the needles  1 - 5  opposite to both sides of the threading hook  20 . Furthermore, each of the guide plates  22 ,  23  has a thread guiding notch formed in a slightly lower position than the threading hook  20  in a direction of extension of the threading hook  20 . By the guide plates  22 ,  23 , it is possible to accurately guide any of the eyes of the needles  1 - 5  to the threading hook  20  in a forward movement. 
     [Main Frame] 
     The main frame  90  of the threading device  10  is fixed to a frame of an arm portion of the sewing machine which is not shown. 
     As shown in  FIG. 4 , the main frame  90  includes an almost planar back plate  91  fixed to and supported on the sewing machine frame and a front frame member  92  bent like a U shape and fixedly coupled to the back plate  91 . The back plate  91  holds a main structure of the positioning mechanism  400 . 
     The front frame member  92  has two left and right sidewall portions  94  and  95  which are mutually opposed to a rear sidewall portion  93  provided in cloth contact with the back plate  91 . The left sidewall portion  94  on a left side in  FIG. 4  (a sewing machine face portion side) has a smaller width (a length in the Y-axis direction) than that of the right sidewall portion  95 . 
     Moreover, the rear sidewall portion  93  is set to have a smaller width (the X-axis direction) than that of the back plate  91 , and the back plate  91  is greatly protruded leftward with respect to the rear sidewall portion  93 . 
     The second support mechanism  200  is disposed on an inner region of the front frame member  92 , and the first support mechanism  100  is disposed on a further inner side thereof. 
     [Second Support Mechanism] 
     As shown in  FIG. 4 , the second support mechanism  200  includes a second frame member  201  bent like an almost L shape and supported movably in the Y-axis direction with respect to the front frame member  92  of the main frame  90 . 
     The second frame member  201  includes a rear sidewall portion  203  opposed to the rear sidewall portion  93  of the front frame member  92 , and a right sidewall portion  204  opposed to the right sidewall portion  95  of the front frame member  92 . 
     As shown in  FIGS. 3 and 4 , cylindrical guide shafts  202  are protruded from upper and lower ends of the right sidewall portion  204 , and a pair of long slots  95   a  is formed in the Y-axis direction on the right sidewall portion  95  of the front frame member  92  opposite to the guide shafts  202 . Each of the guide shafts  202  is inserted through each of the slots  95   a  and has C rings  205  attached to a tip part thereof so that a slip from the slots  95   a  can be prevented. 
     When each of the guide shafts  202  is moved along the slot  95   a , the second frame member  201 , that is, the whole second support mechanism  200  can be moved in the Y-axis direction. 
     Furthermore, a bracket-shaped transmitting arm (an operation transmitting arm)  206  is protruded rearward from the rear sidewall portion  203  of the second frame member  201  and penetrates a horizontal through hole  90   a  provided on the main frame  90  and is thus coupled to the positioning mechanism  400  which will be described below. 
     [First Support Mechanism] 
     As shown in  FIG. 4 , the first support mechanism  100  includes a first frame member  101  supported movably in the X-axis direction with respect to the second frame member  201  of the second support mechanism  200 . 
     The first frame member  101  includes a rear sidewall portion  103  opposed to the rear sidewall portion  203  of the second frame member  201 , two left and right sidewall portions  104 ,  105  bent at a right angle from both ends of the rear sidewall portion  103  and opposed to each other, and a front sidewall portion  106  bent from one end of the right sidewall portion  105  and formed along an X-Z plane. 
     As shown in  FIGS. 3 and 4 , the rear sidewall portion  103  is vertically provided with two support brackets  107  for inserting and supporting the threading shaft  11  movably in a vertical direction. 
     Moreover, a cylindrical guide shaft  102  is protruded from upper and lower ends of the rear sidewall portion  103 , and a pair of upper and lower slots  203   a  for inserting the respective guide shafts  102  is formed in the X-axis direction on the rear sidewall portion  203  of the second frame member opposite to the guide shafts  102 . Each of the guide shafts  102  is inserted through each of the slots  203   a  and has a C ring  108  attached to a tip part thereof, thereby preventing a slip from the slot  203   a.    
     The guide shaft  102  is slid along the slot  203   a  so that the first frame member  101  can be moved in the X-axis direction. More specifically, the first support mechanism  100  can be moved in the X-axis direction with respect to the second frame member  201  so that all the structures supported by the first frame member  101  can be moved in the X-axis and Y-axis directions with respect to the main frame  90  in cooperation of the first support mechanism  100  with the second support mechanism  200 . 
     The left sidewall portion  104  is provided with a bracket  109  taking an almost U shape seen from a front and a tip part thereof is coupled to the positioning mechanism  400  which will be described below, and a moving force is transmitted from the bracket  109  to the first frame member  101  in the X-axis direction. 
     Moreover, a boss-shaped engaging projection  109   b  provided in an upper surface portion of the bracket  109  is engaged with a forked coupling arm  71   a  provided in an indicator moving member  71  of the selected needle indicating device  70  which will be described below, and has the function of transmitting a moving operation in the X-axis direction of the first frame member  101  to the indicator moving member  71 . 
     As shown in  FIGS. 1 and 2 , the front sidewall portion  106  is provided with guide grooves  106   a ,  106   b  for guiding a movement to a standby position and a threading position of a moving member  61  in the thread holding member support mechanism  60 . 
     [Positioning Mechanism] 
     The positioning mechanism  400  will be described with reference to  FIGS. 4 ,  6 ,  7 ,  8  and  9 . 
     The positioning mechanism  400  has each structure supported mainly on the back plate  91  of the main frame  90 . 
     The positioning mechanism  400  includes the selecting dial  401  for sequentially switching the position of the threading shaft  11  into the needles  1 - 5  so as to select one of the needles  1 - 5  through which a thread is to be inserted, a stage switching portion  410  for intermittently dividing a rotating operation of the selecting dial  401  corresponding to the positions of the respective needles  1 - 5 , a first cam mechanism  420  for giving a moving operation in the X-axis direction to the threading shaft  11  through the operation of the selecting dial  401 , and a second cam mechanism  430  for giving a moving operation in the Y-axis direction to the threading shaft  11  through the operation of the selecting dial  401 . 
     [Selecting Dial and Stage Switching Portion] 
     As shown in  FIGS. 6 and 7 , the selecting dial  401  is fixed to one end of a rotating support shaft  422  for pivotally supporting a first cam  421  of the first cam mechanism  420 . 
     As shown in  FIG. 8 , moreover, the stage switching portion  410  includes a rotor  411  of the stage switching portion  410  fixed to the other end of the rotating support shaft  422  and a leaf spring  417  having one end fixed to the back plate  91 . 
     Engaging concave portions  412 - 416  corresponding to the needles  1 - 5  respectively are formed on a part of an outer periphery of the rotor  411 , and the leaf spring  417  has a tip part provided with a projection capable of being fitted into the engaging concave portions  412 - 416 , and always has an elastic force for causing the projection to come in pressure contact with the outer periphery of the rotor  411  and the projection is fitted into the engaging concave portions  412 - 416  to control the rotation of the rotor  411 . 
     When the selecting dial  401  is rotated, therefore, the leaf spring  417  is moved back and forth to the engaging concave portions  412 - 416  by its own elastic force, thereby controlling the rotation into a fitting position, that is, one of the positions corresponding to the needles  1 - 5 . 
     [First Cam Mechanism] 
     As shown in  FIG. 7 , the first cam mechanism  420  includes the rotating support shaft (first rotating support shaft)  422  supported rotatably with respect to the back plate  91  in the X-axis direction, the first cam  421  taking a cylindrical shape which is fixed to the rotating support shaft  422  and has an almost spiral cam groove  421   a  formed on an outer periphery (which is not shown in  FIG. 4 ), and an oscillating arm  423  having an intermediate portion  423   d  supported rotatably around a vertical axis with respect to the back plate  91  and a projection  423   a  to be a cam follower which is engaged with the cam groove  421   a.    
     As shown in  FIG. 4 , the bracket  109  of the first support mechanism  100  has a slot  109   a  formed in the Y-axis direction and an engaging pin  423   b  of the oscillating arm  423  is inserted into the slot  109   a . The oscillating arm  423  is coupled to the bracket  109  provided on the first frame member  101  through the engaging pin  423   b  provided on the other end thereof. 
     When the first cam  421  is rotated in a clockwise direction as seen from a left, a moving force is applied in the X-axis direction (a rightward direction) to the follower projection  423   a  of the oscillating arm  423 . Consequently, the other end of the oscillating arm  423  generates a leftward movement so that the first frame member  101  is moved in a leftward direction through the bracket  109 . When the first cam  421  is rotated in a reverse direction, moreover, the first frame member  101  generates a movement in a rightward direction. 
     The slot  109   a  of the bracket  109  serves to permit a displacement in the Y-axis direction which is generated in a rotation of the other end of the oscillating arm  423 , and furthermore, to permit a movement in the Y-axis direction of the first frame member  101  with a movement in the Y-axis direction of the second frame member  201  through the second cam mechanism  430  which will be described below. 
     [Second Cam Mechanism] 
     The second came mechanism  430  has a second cam  431  for oscillating the oscillating arm  423  and linearly moving the oscillating arm  423  in the X-axis direction, a rotating support shaft (a second rotating support shaft)  432  supported rotatably in the X-axis direction with respect to the back plate  91 , a follower projection  433  provided on the rotating support shaft  432  and serving to convert the linear movement of the second cam  431  into a rotating operation and to transmit the rotating operation to the rotating support shaft  432 , and an almost L-shaped link member  434  for applying a moving operation in the Y-axis direction through the operation transmitting arm  206  to the second frame member  201  by the rotation of the rotating support shaft  432 . 
     The second cam  431  taking such a shape as to take a part of an outer peripheral surface taking a shape of a hollow cylinder away is supported slidably in the X-axis direction through the rotating support shaft  432 . 
     Moreover, the outer peripheral surface of the second cam  431  is provided with an engaging projection  43  la which is protruded outward, and the engaging projection  431   a  is inserted into a slot  423   c  formed in a longitudinal direction at one end side of the oscillating arm  423 . When the oscillating arm  423  is oscillated by the rotation of the first cam  421 , the second cam  431  is moved in the X-axis direction. A detent  435  shown in  FIG. 7  controls the movement in the Y-axis direction of the engaging projection  431   a  and the rotation of the second cam  431  through the insertion of the engaging projection  431   a  of the second cam  431  into a slot  435   a  formed in the X-axis direction. 
     Furthermore, the outer peripheral surface of the second cam  431  is provided with a guide hole  431   b  into which a tip part of the follower projection  433  is inserted. The guide hole  431   b  has an almost spiral section (an inclined portion in  FIG. 7 ) formed in an intermediate part thereof. When the follower projection  433  is engaged with the almost spiral section, it is moved in a circumferential direction to rotate the rotating support shaft  432 . 
     A link member  434  having a lower end supported pivotally on the rotating support shaft  432  has an upper end coupled to the transmitting arm  206  extended from the second frame member  201 . When the link member  434  is rotated interlockingly with the rotation of the rotating support shaft  432 , the transmitting arm  206  is moved in the Y-axis direction so that the second frame member  201  and the first frame member  101  which are coupled to the transmitting arm  206  are moved in the Y-axis direction. 
     [Operation of Positioning Mechanism] 
     Next, a switching operation in five stages of the selecting dial  401  will be described with reference to  FIG. 9 . 
     (1) A state in which the selecting dial  401  is adjusted into a position in which the engaging projection of the leaf spring  417  is fitted in the engaging concave portion  412  is set to be a first state. At this time, the projection  423   a  is placed in a first position of  FIG. 9A  at one end side of the cam groove  421   a  and the first frame member  101  is positioned on a rightmost side. Moreover, the follower projection  433  is placed in a first position of  FIG. 9B  at one end side of the guide hole  431   b  and the second frame member  201  is positioned on a rearmost side. By the arrangement of the first and second frame members  101  and  201 , the threading shaft  11  is placed in a position in which the threading hook  20  inserts a thread through the needle  1 . 
     (2) A state in which the selecting dial  401  is adjusted into a position in which the engaging projection of the leaf spring  417  is fitted in the engaging concave portion  413  is set to be a second state. At this time, the projection  423   a  is placed in a second position of  FIG. 9A  in the cam groove  421   a  and the first frame member  101  generates a leftward movement. Moreover, the follower projection  433  is placed in a second position of  FIG. 9B  in the guide hole  431   b  and the second frame member  201  does not generate the movement in the state of (1). In this case, a moving distance of the first frame member  101  is coincident with an interval in the X-axis direction between the needles  1  and  2 . By the arrangement of the first and second frame members  101  and  201 , the threading shaft  11  is placed in a position in which the threading hook  20  inserts a thread through the needle  2 . 
     (3) A state in which the selecting dial  401  is adjusted into a position in which the engaging projection of the leaf spring  417  is fitted in the engaging concave portion  414  is set to be a third state. At this time, the projection  423   a  is placed in a third position of  FIG. 9A  in the cam groove  421   a  and the first frame member  101  generates the leftward movement. Moreover, the follower projection  433  is placed in a third position of  FIG. 9B  in the guide hole  431   b  and the second frame member  201  generates a movement toward a front side. In this case, a moving distance of the first frame member  101  is coincident with an interval in the X-axis direction between the needles  2  and  3  and a moving distance of the second frame member  201  is coincident with an interval in the Y-axis direction between the needles  2  and  3 . By the arrangement of the first and second frame members  101  and  201 , accordingly, the threading shaft  11  is placed in a position in which the threading hook  20  inserts a thread through the needle  3 . 
     (4) A state in which the selecting dial  401  is adjusted into a position in which the engaging projection of the leaf spring  417  is fitted in the engaging concave portion  415  is set to be a fourth state. At this time, the projection  423   a  is placed in a fourth position of  FIG. 9A  in the cam groove  421   a  and the first frame member  101  generates the leftward movement. Moreover, the follower projection  433  is placed in a fourth position of  FIG. 9B  in the guide hole  431   b  and the second frame member  201  does not generate the movement in the state of (3). In this case, a moving distance of the first frame member  101  is coincident with an interval in the X-axis direction between the needles  3  and  4 . By the arrangement of the first and second frame members  101  and  201 , the threading shaft  11  is placed in a position in which the threading hook  20  inserts a thread through the needle  4 . 
     (5) A state in which the selecting dial  401  is adjusted into a position in which the engaging projection of the leaf spring  417  is fitted in the engaging concave portion  416  is set to be a fifth state. At this time, the projection  423   a  is placed in a fifth position of  FIG. 9A  in the cam groove  421   a  and the first frame member  101  generates the leftward movement. Moreover, the follower projection  433  is placed in a fifth position of  FIG. 9B  in the guide hole  431   b  and the second frame member  201  does not generate the movement in the state of (3). In this case, a moving distance of the first frame member  101  is coincident with an interval in the X-axis direction between the needles  4  and  5 . By the arrangement of the first and second frame members  101  and  201 , the threading shaft  11  is placed in a position in which the threading hook  20  inserts a thread through the needle  5 . 
     By carrying out the position switching operation over the selecting dial  401  from the first state to the fifth state in order as shown in the (1) to (5), it is possible to position the threading shaft  11  in the position in which the threading hook  20  can insert the thread into the positions of the needles  1 - 5 , thereby carrying out the threading work over them. 
     [Threading Mechanism] 
     The threading mechanism  300  will be described with reference to  FIGS. 2 ,  3  and  10  to  14 . 
     The threading mechanism  300  includes an operation lever  310  to be operating means for moving the threading shaft  11  downward and giving a threading operation, a threading slide guide  320  to be an up-down frame member for carrying out a downward moving operation together with the threading shaft  11  through a downward operation of the operation lever  310 , a height regulating mechanism  330  for blocking the downward movement of the threading shaft  11  in a plurality of heights corresponding to the heights of the eyes of the needles  1 - 5 , and a threading cam mechanism  340  for rotating the threading shaft  11  in such a direction that the threading hook  20  is moved forward when only the threading slide guide  320  is moved downward with respect to the threading shaft  11 . 
     [Threading Slide Guide] 
     The threading slide guide  320  includes a back plate  321  which is vertically long and has an arcuate section, plate-shaped support portions  322  and  323  provided integrally with both of upper and lower ends thereof and provided with through holes for inserting the threading shaft  11  therethrough, and an engaging shaft  324  with the operation lever  310  extended leftward in the X-axis direction from the back plate  321 . 
     The support portions  322  and  323  are plate-shaped along an X-Y plane and are provided with through holes for inserting the threading shaft  11  therethrough, and the threading slide guide  320  is coupled to the threading shaft  11  slidably along the threading shaft  11  via the through holes. A compression coil spring  325  is inserted between the upper support portion  322  and a first guide pin  331  provided on the threading shaft which will be described below, and a stopper  11   a  to abut on an upper surface of the support portion  322  is provided on an upper end of the threading shaft  11 . Therefore, the threading shaft  11  and the threading slide guide  320  are always energized in a state in which the threading shaft  11  is pressed downward and the threading slide guide  320  is pressed upward. 
     [Operation Lever] 
     As shown in  FIGS. 3 and 10 , the operation lever  310  is provided on a left side surface of the left sidewall portion  94  of the main frame  90  and has a vertical slot  311  for inserting two guide shafts  96  protruded leftward in upper and lower positions on a left side surface of the left sidewall portion  94 , and is held by a C ring  97  provided in a tip part of each of the guide shafts  96  so as not to slip off. The operation lever  310  is supported to be vertically movable with respect to the main frame  90  by the structure. 
     The operation lever  310  includes a long body portion  312  in a vertical direction, an arm portion  313  extended in an orthogonal direction (the Y-axis direction) to the body portion  312  in the vicinity of the middle of the body portion  312 , and a thread holding member operating portion  314  bent at a right angle in a tip part of the arm portion  313  and extended in the X-axis direction. 
     The slot  311  is formed to penetrate the body portion  312 . Moreover, a lower end of the body portion  312  is bent at a right angle so that a protruded portion  315  extended in the X-axis direction is formed and a downward pressing operation is carried out therein. Furthermore, the body portion  312  is coupled to the main frame  90  through a tension spring  316  and an upward tensile force is always energized. 
     On the other hand, a slot  317  is formed to penetrate the arm portion  313  in the Y-axis direction and the engaging shaft  324  extended from the threading slide guide  320  is inserted therein. Accordingly a downward moving operation applied to the operation lever  310  is transmitted from the arm portion  313  to the threading slide guide  320  and the threading shaft  11  through the engaging shaft  324 . The slot  317  of the arm portion  313  is provided in the Y-axis direction in order to permit a movement in the Y-axis direction through the second support mechanism  200 . 
     The thread holding member operating portion  314  serves to give an operation for moving the thread holding member  50  close to the needle side in the forward movement of the threading hook  20 . The thread holding member operating portion  314  is provided in the operation lever  310  to implement an interlocking motion of the forward moving operation of the threading hook  20  and the close motion of the thread holding member  50 . An action of the thread holding member operating portion  314  on the thread holding member  50  will be described in detail in an explanation of the thread holding member support mechanism  60 . 
     [Threading Cam Mechanism] 
     The threading cam mechanism  340  includes an engaging projection  341  protruded in a horizontal direction from the threading shaft  11  toward the back plate  321  of the threading slide guide  320  and a slot portion  342  to be a groove cam formed on the back plate  321  of the threading slide guide  320 . 
     The engaging projection  341  actually serves as a rear end of the first guide pin  331  provided to penetrate the threading shaft  11  which will be described below. The engaging projection  341  is set to have such a length as to be inserted into the slot portion  342  formed to penetrate the back plate  321  and to penetrate the back plate  321  to an outside. The slot portion  342  is formed with a longitudinal direction inclined to a vertical direction. The engaging projection  341  is maintained to be usually positioned on a lower end of the slot portion  342  by an action of the compression coil spring  325  provided between the threading shaft  11  and the threading slide guide  320 . The slot portion  342  is inclined in such a direction as to generate a displacement in a direction in which the threading shaft  11  is rotated toward the forward movement of the threading hook  20  when the engaging projection  341  is moved upward along the slot portion  342 . More specifically, the threading shaft  11  is rotated clockwise as seen on a plane so that the threading hook  20  is moved forward. Therefore, the slot portion  342  is inclined upward in such a direction as to be turned toward the rear side in the Y-axis direction. 
     In the case in which the threading slide guide  320  is relatively moved downward with respect to the threading shaft  11 , the engaging projection  341  is moved upward along the slot portion  342 . As described above, the threading shaft  11  and the threading slide guide  320  are moved vertically until a greater force than a pressing force of the compression coil spring  325  is applied by the action of the compression coil spring  325  provided between the threading shaft  11  and the threading slide guide  320  and the stopper  11   a  provided on the upper end of the threading shaft  11 . Accordingly, the height regulating mechanism  330  for blocking a downward movement is provided in the middle of a downward moving path of the threading shaft  11 . When the downward moving operation is applied to the threading slide guide  320  and the threading shaft  11  through the operation lever  310 , the downward movement of only the threading shaft  11  is blocked in the middle. In this case, when a greater pressing force than the compression coil spring  325  is applied from the operation lever  310 , the threading slide guide  320  is relatively moved downward with respect to the threading shaft  11  so that the threading shaft  11  is rotated by the action of the threading cam mechanism  340  and the threading hook  20  is moved forward to carry out the threading operation. The threading hook  20  is moved backward by a return force of the compression coil spring  325  through the release of the operation lever  310 . 
     [Height Regulating Mechanism] 
     The height regulating mechanism  330  has the function of blocking the downward movement of only the threading shaft  11  in order to operate the threading cam mechanism  340  and the function of regulating the height of the threading hook  20  for each of the needles  1 - 5  in cooperation with the positioning mechanism  400  for moving and positioning the threading shaft  11  corresponding to the arrangement of the needles  1 - 5  in the threading operation of the needles  1 - 5 . 
     More specifically, the height regulating mechanism  330  includes first and second guide pins  331 ,  332  provided on the threading shaft  11 , a lower threading guide  350  having five abutting portions  351 - 355  on which either one of the guide pins  331 ,  332  abuts from above, and an upper threading guide  360  (which is not shown in  FIG. 10 ) for guiding a revolution of each of the guide pins  331 ,  332  in the rotation of the threading shaft  11 . 
     Both of the first and second guide pins  331 ,  332  are provided perpendicularly to the threading shaft  11 , and the first guide pin  331  is disposed in an upper position. Moreover, the two guide pins  331 ,  332  are disposed on the threading shaft  11  at different angles around the threading shaft  11  over the X-Y plane. 
     As shown in  FIG. 13A , the abutting portion  351  is disposed in a position in which the first guide pin  331  is moved downward to abut thereon when the threading shaft  11  is placed in a position in which the thread is to be inserted through the needle  1 . As shown in  FIG. 13B , the abutting portion  352  is disposed in a position in which the first guide pin  331  is moved downward to abut thereon when the threading shaft  11  is placed in a position in which the thread is to be inserted through the needle  2 . As shown in  FIG. 13C , the abutting portion  353  is disposed in a position in which the second guide pin  332  is moved downward to abut thereon when the threading shaft  11  is placed in a position in which the thread is to be inserted through the needle  3 . As shown in  FIG. 13D , the abutting portion  354  is disposed in a position in which the second guide pin  332  is moved downward to abut thereon when the threading shaft  11  is placed in a position in which the thread is to be inserted through the needle  4 . As shown in  FIG. 13E , the abutting portion  355  is disposed in a position in which the second guide pin  332  is moved downward to abut thereon when the threading shaft  11  is placed in a position in which the thread is to be inserted through the needle  5 . 
     Moreover, all of the planes of the abutting portions  351 - 355  are formed to have substantially arcuate shapes in such a manner that the guide pins  331 ,  332  can maintain the abutting state when the threading shaft  11  abuts to carry out the rotation. 
     Furthermore, the abutting portions  351 - 355  serve to determine the heights of the threading shaft  11  and the threading hook  20  in the threading operation respectively. Therefore, respective planar heights are set to be varied depending on the heights of the eyes of the needles  1 - 5 . 
     In addition, the abutting portions  351  and  352  and the abutting portions  353 ,  354  and  355  are disposed apart from each other depending on opening angles of the guide pins  331 ,  332  around the threading shaft  11  respectively. Thus, a plurality of abutting portions is distributed and disposed corresponding to the number of the guide pins to avoid an interference with the arrangement of each of the abutting portions. 
     Moreover, two guide pins  331 ,  332  are present. A difference in a height is made between the first guide pin  331  and the second guide pin  332  in such a manner that one of the guide pins  331 ,  332  does not abut on any of the abutting portions when the other abuts on the abutting portion. Furthermore, a relief portion  356  is formed to be partially lower than an upper surface in such a manner that one of the guide pins does not abut on a portion other than the abutting portion of the lower threading guide  350  when the other guide pin abuts on the abutting portion (see  FIG. 13A ). 
     The lower threading guide  350  has the function of determining the height of the threading hook  20  in the threading operation. For this reason, a height of a certain section is always required. Accordingly, a sewing machine motor is controlled in such a manner that the needle bar is set to have an upper shaft angle in a predetermined certain section to always obtain the same threading enable section in the threading operation. 
     In  FIG. 14 , the upper threading guide  360  has the function of guiding the guide pin in abutment from above so as to maintain an abutment when any of the guide pins  331 ,  332  abutting on the abutting portions  351 - 355  of the lower threading guide  350  is moved over the upper surfaces of the abutting portions  351 - 355  through the rotation of the threading shaft  11 . 
     As shown in  FIG. 14 , accordingly, the upper threading guide  360  includes a guide portion  361  for guiding in abutment when the first guide pin  331  is moved in abutment on the abutting portion  351  of the lower threading guide  350 , a guide portion  362  for guiding in abutment when the first guide pin  331  is moved in abutment on the abutting portion  352 , a guide portion  363  for guiding in abutment when the second guide pin  332  is moved in abutment on the abutting portion  353 , a guide portion  364  for guiding in abutment when the second guide pin  332  is moved in abutment on the abutting portion  354 , a guide portion  365  for guiding in abutment when the second guide pin  332  is moved in abutment on the abutting portion  355 , a relief portion  366  for permitting a downward movement of the first guide pin  331  in the downward movement of the threading shaft  11 , and a relief portion  367  for permitting a downward movement of the second guide pin  332  in the downward movement of the threading shaft  11 . 
     [Thread Holding Portion] 
     The thread holding portion  50  is a member formed by bending a plate, and includes two thread guarding portions  51 ,  52  for guarding a thread at a lower end and an interposing portion  53  having a leaf spring for interposing the thread end as shown in  FIG. 2 . The two thread guarding portions  51 ,  52  have notches for guarding a thread respectively (not shown) and the thread is provided over them and can be thus laid in the X-axis direction. Moreover, the interposing portion  53  comes in pressure contact with a holding plate and the leaf spring and can interpose the thread end through an insertion therein. Moreover, the interposing portion  53  is adjacent in a direction in which the two thread guarding portions  51 ,  52  are provided side by side. The interposing portion  53  is caused to interpose a residual end of the thread in the case in which the thread guarding operation is carried out with the thread laid over the two thread guarding portions  51 ,  52 . Consequently, the thread can be maintained to be stretched in the X-axis direction between the two thread guarding portions  51 ,  52 . 
     By interposing the thread and disposing the thread holding member  50  at an opposite side to the threading hook  20  in a state in which the thread is stretched in the X-axis direction, thus, it is possible to smoothly catch the thread through a return part in a rearward movement when the threading hook  20  moved forward in the Y-axis direction passes just above the thread which is orthogonal thereto. 
     [Thread Holding Member Support Mechanism] 
     As shown in  FIGS. 2 and 4 , the thread holding member support mechanism  60  includes the moving member  61  to be moved by the guide grooves  106   a ,  106   b  of the front sidewall portion  106  while holding the thread holding portion  50  oscillatably, an interlocking member  62  for moving the moving member  61  downward with the downward movement of the threading shaft  11 , and an oscillating lever  63  for oscillating the thread holding portion  50  placed in a threading position toward the needle side. 
     The moving member  61  is a long plate and is disposed in a vertical direction, and guide shafts  64  are provided in two places in an upper part thereof. The guide shafts  64  are inserted into the guide grooves  106   a ,  106   b  of the front sidewall portion  106  respectively and are fixed with a C ring  65  from a front side. With the structure, the moving member  61  can carry out a movement along the guide grooves  106   a ,  106   b . A position of the thread holding portion  50  in the case in which the moving member  61  is placed on upper ends of the guide grooves  106   a ,  106   b  is set to be a standby position, and a position of the thread holding portion  50  in the case in which the moving member  61  is positioned on lower ends of the guide grooves  106   a ,  106   b  is set to be a threading position. 
     A boss-shaped projection  61   b  is provided on a rear side of an upper end of the moving member  61 , and the interlocking member  62  to carry out an up-down motion together with the threading shaft  11  abuts thereon from above. 
     Furthermore, the moving member  61  includes a plane portion  61   a  obtained by bending a lower part thereof at a right angle and provided along a Y-Z plane, and the thread holding portion  50  is pivotally supported through a support shaft in the X-axis direction at a lower end of the plane portion  61   a . Moreover, the oscillating lever  63  is pivotally supported by the support shaft which is also provided in the X-axis direction in an upper part of the plane portion  61   a.    
     The thread holding portion  50  has the abutting portion  54  on the oscillating lever  63  above the support shaft. 
     On the other hand, the oscillating lever  63  has the oscillating portion  63   a  suspended downward, and the oscillating portion  63   a  is provided with a projection  63   b . The projection  63   b  abuts on the abutting portion  54  of the thread holding portion  50  from a rear side. Moreover, the oscillating lever  63  is provided, at an upper rear side thereof, with an engagement extending portion  63   c  on which the thread holding member operating portion  314  of the operation lever  310  abuts from above. When the thread holding member operating portion  314  of the operation lever  310  abuts on the engagement extending portion  63   c  from above, the oscillating portion  63   a  of the oscillating lever  63  is oscillated so that the projection  63   b  presses the abutting portion  54  of the thread holding portion  50  toward a front side to oscillate the thread holding portion  50 . By the oscillation, the thread guarding portions  51 ,  52  provided at the lower end of the thread holding portion  50  can approach the needle  1  to  5  side to transfer the thread to the threading hook  20 . 
     The moving member  61  of the thread holding member support mechanism  60  is downward moved interlockingly with the threading shaft  11  through the interlocking member  62 . When the threading shaft  11  is regulated to have a proper height through each of the abutting portions  351 - 355  of the lower threading guide  350 , therefore, the thread holding portion  50  can also be regulated to have a proper height through the moving member  61 . 
     [Selected Needle Indicating Device] 
     As shown in  FIGS. 16 and 17 , the selected needle indicating device  70  includes the indicator moving member  71  to be moved together with the first frame member  101  in only the X-axis direction, a panel  72  (display means) having selection indicating windows  72   a - 72   e  corresponding to the respective needles  1 - 5 , an indicator  73  which is coupled to the indicator moving member  71  and is placed into a position which selectively faces one of the selection indicating windows  72   a - 72   e  from a rear side of the panel  72 , and a slide table  74  for reciprocably supporting the indicator  73  in the X-axis direction. 
     The indicator moving member  71  has the indicator  73  fixed to an upper part thereof and is supported movably in the X-axis direction through the slide table  74  integrally with the indicator  73 . The indicator moving member  71  is provided with two coupling arms  71   a  extended in the Y-axis direction. The coupling arms  71   a  have such a structure that they are extended in parallel with each other in a cantilever state and are engaged with each other to interpose the engaging projection  109   b  provided on the bracket  109  of the first frame member  101  therebetween. An interval between the two coupling arms  71   a  is set to be greater than at least an outside diameter of the engaging projection  109   b , and the engaging projection  109   b  can be smoothly moved in the Y-axis direction between the two coupling arms  71   a.    
     The first frame member  101  supports the threading shaft  11  and carries out a movement in the X-axis direction and the Y-axis direction when the needle to perform the threading operation is to be selected. On the other hand, the indicator moving member  71  has such a structure that the engaging projection  109   b  is interposed between the two coupling arms  71   a  extended in the Y-axis direction. When the first frame member  101  is moved, therefore, only the moving operation in the X-axis direction is transmitted to the indicator moving member  71 . 
     All of the needles  1 - 5  are disposed in different positions in the X-axis direction. When the thread is to be inserted through the needles  1 - 5 , therefore, the indicator moving member  71  is also moved to five fixed positions in the X-axis direction respectively. 
     The slide table  74  is fixed to a rear face of a cover  12  of the sewing machine. A front face portion is provided with a rectangular opening portion  74   a  in the X-axis direction, and the indicator  73  is fitted in the opening portion  74   a  slidably along the opening portion  74   a . The opening portion  74   a  penetrates a bottom face side, and the indicator moving member  71  positioned on the bottom face side and the indicator  73  can be coupled to each other. 
     The indicator  73  has a prismatic bar-shaped portion  73   a  extended in a vertical direction, and a front face of the bar-shaped portion  73   a  is set to have a bright color or a fluorescent color. On the other hand, a front face portion of the slide table  74  is set to have a black color or a dark color and a contrast is given in such a manner that the bar-shaped portion  73   a  of the indicator  73  becomes striking. 
     As shown in  FIG. 15 , the panel  72  is fixed to the surface of the cover  12  of the sewing machine in such a manner that an operator can carry out a visual confirmation from an outside, particularly, a front side of the sewing machine where the operator is placed in the threading work, and is disposed on the front side of the slide table  74 . The panel  72  is a square plate and the slit-shaped selection indicating windows  72   a - 72   e  in the vertical direction are formed in a penetration. The selection indicating windows  72   a - 72   e  are provided on the level with the bar-shaped portion  73   a  of the indicator  73 . The selection indicating windows  72   a - 72   e  are set into the same positions in the X-axis direction as the bar-shaped portion  73   a  of the indicator  73  when the indicator moving member  71  is moved to the respective fixed positions in the threading operation for the needles  1 - 5 . In other words, when the thread is to be inserted through each of the needles  1 - 5 , the bar-shaped portion  73   a  of the indicator  73  is positioned in one of the five selection indicating windows  72   a - 72   e  in a one-to-one relationship. In the case in which the bar-shaped portion  73   a  of the indicator  73  is positioned in one of the selection indicating windows  72   a - 72   e , consequently, the bright color or the fluorescent color can be visually recognized through only one of the selection indicating windows and only the black color or dark color of the slide table  72  can be visually recognized through four other selection indicating windows. By confirming one of the selection indicating windows  72   a - 72   e  that has the bright color or the fluorescent color, therefore, it is possible to distinguish the needle selected among the needles  1 - 5 . 
     Moreover, the panel  72  shows the selected one of the needles  1 - 5  on the surface (front side) of the cover  12  of the sewing machine. Therefore, the operator of the sewing machine is opposed to the panel  72  so that the indication can be recognized clearly. The surface (front side) of the cover  12  of the sewing machine indicates a surface at an upstream side in a feeding direction of a workpiece. 
     As shown in  FIG. 15 , furthermore, the selecting dial  401  is protruded leftward from a left side surface of the cover  12  of the sewing machine and is not present on the same surface as the panel  72  but is disposed behind the panel  72 . Therefore, an arm of the operator to manipulate the selecting dial  401  does not disturb the recognition of the panel  72  so that the indication can be recognized clearly. 
     [Operation of Threading Device] 
     Description will be given to the threading operation of the threading device  10  having the configuration described above. 
     First of all, the needles  1 - 5  for inserting the thread therethrough are selected by the rotating operation of the selecting dial  401 . 
     At this time, the first cam mechanism  420  moves the first frame member  101  of the first support mechanism  100  in the X-axis direction and the second cam mechanism  430  moves the second frame member  201  of the second support mechanism  200  in the Y-axis direction depending on the angular position of the selecting dial  401 . By their cooperation, the threading shaft  11  is moved and placed in a predetermined position in the X-Y plane. 
     At this point, in the height regulating mechanism  330 , it is determined as to which of the guide pins  331 ,  332  abut on which of the abutting portions  351 - 355 . 
     When the operation lever  310  is manipulated downward, then, the threading shaft  11  starts a downward moving operation together with the threading slide guide  320 . Moreover, the moving member  61  is pressed downward by the interlocking member  62  provided on the upper end of the threading shaft  11  so that the thread holding portion  50  also starts the downward moving operation. 
     When the predetermined guide pins  331 ,  332  extended from the threading shaft  11  abut on the predetermined abutting portions  351 - 355 , thereafter, the downward moving operation is blocked so that the threading shaft  11  and the threading hook  20  are regulated into the height of the selected needle depending on the set height of the abutting portion. Moreover, the thread holding portion  50  to be interlocked through the interlocking member  62  is also regulated into the height of the selected height. 
     At this point, when the operation lever  310  is further pressed downward, only the threading slide guide  320  is moved downward with respect to the threading shaft  11 . As a result, the threading shaft  11  is rotated clockwise by the action of the threading cam mechanism  340 . Moreover, the thread holding member operating portion  314  of the operation lever  310  presses the oscillating portion  63   c  of the oscillating lever  63  from above to rotate the oscillating lever  63 . As a result, the threading hook  20  is moved forward and is inserted into the eye of the predetermined needle so that the thread holding portion  50  is tilted toward the needle side to cause the thread stretched in the X-axis direction to approach the front face of the threading hook  20 . As a result, the return part of the threading hook  20  catches the thread. 
     When the operation lever  310  is released from the downward pressing state, then, the threading hook  20  starts the backward movement to pull the caught thread into the eye of the needle so that the threading work is executed. 
     In the case in which the thread is inserted through the other needles, furthermore, the selecting dial  401  is rotated to downward manipulate the operation lever  310  again. 
     Moreover, the operation of the selected needle indicating device  70  in the case in which the needles  1 - 5  for carrying out the threading work are selected by the rotating operation of the selecting dial  401  will be described with reference to  FIG. 18 . 
     When the thread is to be inserted through each of the needles  1 ,  2 ,  3 ,  4  and  5 , the first frame member  101  and the threading shaft  11  are moved in the X-axis direction and the Y-axis direction through the positioning mechanism  400 . In  FIG. 18 , a change in the position of the bracket  109  with the movement to each position is indicated as  1091 ,  1092 ,  1093 ,  1094  and  1095 . When the threading shaft  11  is aligned with the needles  1 - 5  in order, the bracket  109  is changed into five positions in the X-axis direction and is changed into two positions in the Y-axis direction as shown. However, only a displacement in the X-axis direction is transmitted to the indicator moving member  71  and the indicator  73 . The bar-shaped portion  73   a  is positioned in the selection indicating window  72   a  when the alignment with the needle  1  is carried out, the bar-shaped portion  73   a  is positioned in the selection indicating window  72   b  when the alignment with the needle  2  is carried out, the bar-shaped portion  73   a  is positioned in the selection indicating window  72   c  when the alignment with the needle  3  is carried out, the bar-shaped portion  73   a  is positioned in the selection indicating window  72   d  when the alignment with the needle  4  is carried out, and the bar-shaped portion  73   a  is positioned in the selection indicating window  72   e  when the alignment with the needle  5  is carried out. Depending on which of the selection indicating windows  72   a - 72   e  is changed to have the bright color or the fluorescent color, accordingly, it is possible to quickly recognize which of the needles  1 - 5  has been selected. 
     The threading device  10  supports the threading shaft  11  to be movable to an optional position on the X-Y plane by means of the first support mechanism  100  and the second support mechanism  200 , and the positioning mechanism  400  selectively carries out a movement and positioning in the five places corresponding to the needles  1 - 5  depending on the rotating operation of the selecting dial  401  in cooperation of the two cam mechanisms  420 ,  430 . 
     As in a sewing machine capable of implementing the overlock stitch and the cover stitch by itself, accordingly, also in the case in which the five needles  1 - 5  are provided and are not simply arranged in a line, for example, it is possible to position the threading shaft  11  through only the rotating operation of the selecting dial  401  without requiring an individual position adjusting operation in a plurality of directions. In addition, it is also possible to carry out the alignment with all of the needles  1 - 5  in order. Accordingly, it is possible to precisely insert the thread through all of the needles  1 - 5 . 
     Moreover, the thread holding portion  50  is provided on the first frame member  101  through the moving member  61 . Therefore, the threading shaft  11  as well as the thread holding portion  50  can be aligned with all of the needles  1 - 5  in order in the X-Y direction through only the rotating operation of the selecting dial  401 . Furthermore, it is possible to precisely insert the thread through all of the needles  1 - 5 . 
     In addition, in the threading device  10 , the abutting portions  351 - 355  of the lower threading guide  350  of the threading mechanism  300  are set to have the heights corresponding to the needles  1 - 5  individually. Therefore, it is possible to regulate the threading hook  20  to have a proper height with respect to the eye of each of the needles  1 - 5 . 
     Also in the case in which the five needles  1 - 5  are provided as in the sewing machine capable of implementing the overlock stitch and the cover stitch by itself, two guide pins  331 ,  332  are provided. Therefore, it is possible to distribute and provide the abutting portions  351 - 355  on the lower threading guide  350  and to properly regulate the height of the threading hook  20 , thereby causing the threading work to be more appropriate. 
     Since the selected needle indicating device  70  is provided, moreover, it is possible to indicate one of the needles  1 - 5  with which the threading shaft  11  is aligned distinguishably from the other needles when carrying out the alignment in accordance with the manipulation of the selecting dial  401 . Differently from the case in which the position of the threading shaft  11  is visually confirmed, accordingly, it is possible to accurately grasp the selected needles  1 - 5 . Furthermore, it is not necessary to carry out an operation for rotating the threading shaft  11  in the confirmation. Therefore, it is possible to eliminate the complicatedness of the confirming work. 
     Moreover, the selected needle indicating device  70  indicates one of the needles  1 - 5  with respect to which the threading shaft  11  is positioned in accordance with a change in the positions of the indicator moving member  71  and the indicator  73  which are moved together with the threading shaft  11 . Therefore, it is not necessary to provide means for electrically detecting the position of the threading shaft  11  and means for displaying information about the position and it is possible to confirm the selected needle with a simple structure. 
     Second Exemplary Embodiment 
     Although the selecting dial  401  (the selecting portion) is protruded leftward from the left side surface of the cover  12  of the sewing machine in the threading device  10  of the first exemplary embodiment, the present invention is not restricted to such an arrangement. Hereinafter, a second exemplary embodiment in which a selecting portion and an arrangement thereof are different from the first exemplary embodiment will be described with reference to  FIGS. 19 to 22 . In the second exemplary embodiment, the same structures as those of the threading device  10  of the first exemplary embodiment have the same reference numerals and description thereof will be omitted. 
     The second exemplary embodiment is different from the first exemplary embodiment in that, instead of the circular selecting dial  401  provided on the rotating support shaft  422  of the first exemplary embodiment, a third rotating support shaft  418 A is provided above the rotating support shaft  422  and a selecting lever  401 A (a selecting portion) is provided on the third rotating support shaft  418 A as shown in  FIG. 19 . 
     More specifically, as shown in  FIGS. 20 and 21 , the third rotating support shaft  418 A is supported rotatably by a back plate  91  in the X-axis direction above the rotating support shaft  422  at a rear side of the back plate  91 , and the selecting lever  401 A is fixed to one end (a left end) thereof. 
     The selecting operation switching lever  401 A includes a lever portion  401   a  extended like a bar outward in a radial direction of a disk which is partially cut away linearly, and is fixed to the third rotating support shaft  418 A in a central position of the disk. 
     Furthermore, a main driving gear  419 A is fixed to the other end (a right end) of the third rotating support shaft  418 A and is engaged with a driven gear  424 A which is newly provided on the rotating support shaft  422 . The driven gear  424 A is fixed to the rotating support shaft  422 . When a rotating operation is applied to the selecting lever  401 A, the driven gear  424 A is rotated through the third rotating support shaft  418 A and the main driving gear  419 A, and furthermore, a first cam  421  is also rotated. Subsequent operations are the same as those of the first exemplary embodiment. 
     Moreover, the stage switching portion  410  is moved to an intermediate position between the rotating support shaft  422  and the third rotating support shaft  418 A. 
     By employing the structure, it is possible to dispose the selecting operation switching lever  401 A rightward and rearward (the rear side) as compared with the selecting dial  401  and to provide the lever portion  401   a  so as to be protruded from the rear side (the rear side) of the sewing machine cover  12  as shown in  FIG. 22 . 
     Consequently, the selecting lever  401 A is disposed on a surface at an opposite side to the indicating position of the panel  72  in the selected needle indicating device  70  in the cover  12 . As compared with the selecting dial  401 , therefore, it is possible to more effectively avoid a problem in that the arm of the operator for executing the operation for selecting the needles  1 - 5  to carry out the threading work causes the indication of the selected needle positioned on the front side of the sewing machine to be shielded or seen with difficulty in the same operation, to confirm the selection of the needle more satisfactorily, and to avoid a selection error and to further enhance a workability. 
     Other Exemplary Embodiments 
     The selected needle indicating device  70  may be provided with a sensor for detecting a change in a position for the threading shaft  11  or a structure to be displaced in the X-axis direction together with the threading shaft  11  and may be provided with a panel for displaying which of the needles  1 - 5  has been selected upon receipt of a signal sent from the sensor. For example, by utilizing a linear scale for detecting a linear moving amount to couple the sensor to the first frame member  101  in the same structure as the indicator moving member  71 , it is possible to detect a position of the threading shaft  11  which corresponds to one of the needles in the X-axis direction. By utilizing a liquid crystal panel to display the needle selected corresponding to a result of the detection, for example, it is possible to quickly recognize the selected needle. 
     Consequently, it is possible to decrease a mechanical movable structure and to enhance durability without an influence of deterioration such as an abrasion. 
     Moreover, the selected needle indicating device  70  may have such a structure that the needle  1 - 5  with respect to which the threading shaft  11  is positioned is indicated with a light emission. For example, it is possible to easily implement the same structure by attaching a light emitting device to the bar-shaped portion  73   a  of the indicator  73  or utilizing the panel  72  in the example which is of a light emitting display type. 
     Consequently, it is possible to distinguish the selected needles  1 - 5  more accurately and immediately. 
     While description has been made in connection with exemplary embodiments of the present invention, those skilled in the art will understand that various changes and modification may be made therein without departing from the present invention. It is aimed, therefore, to cover in the appended claims all such changes and modifications falling within the true spirit and scope of the present invention.