Patent Publication Number: US-8539892-B2

Title: Sewing machine and computer-readable medium storing sewing machine control program

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2009-203642, filed Sep. 3, 2009, the content of which is hereby incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a sewing machine that is used in a sewing system that performs sewing of a single embroidery pattern using a plurality of sewing machines and to a computer-readable medium that stores a sewing machine control program. 
     A sewing system is known in which a plurality of multi-needle sewing machines are connected to one another. The known embroidery sewing system includes a plurality of multi-needle sewing machines and performs sewing of a single embroidery pattern using the plurality of multi-needle sewing machines. More specifically, the embroidery sewing system allocates to each of the multi-needle sewing machines a partial pattern that constitutes a portion of the embroidery pattern, such that the number of times that the thread spools are replaced within the embroidery sewing system is reduced and the sewing time is shortened. Each of the multi-needle sewing machines performs sewing of the partial pattern that has been allocated to it. 
     SUMMARY 
     In the known sewing system, cases may occur in which the sewing cannot be performed under the same conditions in every one of the sewing machines included in the sewing system. For example, cases may occur in which the attached positions of embroidery frames in relation to embroidery devices with which the sewing machines are provided differ from one sewing machine to the next, due to attaching errors and the like. In a case where the partial patterns are not sewn under the same conditions in every one of the sewing machines, the possibility arises that the relative positions of the partial patterns that are sewn in the different sewing machines will be unintentionally altered and the appearance of the embroidery pattern will be impaired. 
     Various exemplary embodiments of the broad principles derived herein provide a sewing machine and a computer-readable medium that stores a sewing machine control program that are capable of matching the positions of partial patterns in a case where a single embroidery pattern is sewn using a plurality of sewing machines. 
     Exemplary embodiments provide a sewing machine that is included in a sewing system that, using a plurality of the sewing machines, performs sewing of a single embroidery pattern on a work cloth that is held by an embroidery frame. The sewing machine includes a transfer device, a sewing device, an image capture device, a condition acquisition device, a data acquisition device, a computation device, a correction device, and a sewing control device. The transfer device includes a carriage to which the embroidery frame can be attached and the transfer device is adapted to transfer the carriage. The sewing device moves a needle bar, to a bottom end of which a needle is attached, up and down. The image capture device is adapted to capture at least one image of at least one marker that is positioned in a marker area. The marker area is on at least one of the embroidery frame that is attached to the carriage and the work cloth that is held by the embroidery frame. The condition acquisition device acquires a pattern condition and a setting condition. The pattern condition is a condition for specifying at least one partial pattern among a plurality of partial patterns that form the embroidery pattern as a whole. The at least one partial pattern is allocated to the sewing machine. The setting condition is a condition for specifying a position and an angle of the embroidery pattern in relation to the at least one marker. The data acquisition device acquires pattern data that are data for sewing the at least one partial pattern that is specified by the pattern condition and that is allocated to the sewing machine. The computation device computes, as a positioning condition, at least one of a reference position and a reference angle of the at least one marker in relation to the carriage, based on image data that are generated by the image capture device. The correction device sets a position and an angle of the partial pattern in relation to the carriage and corrects the pattern data that are acquired by the data acquisition device based on the positioning condition that is computed by the computation device and on the setting condition that is acquired by the condition acquisition device. The sewing control device performs sewing of the partial pattern by controlling the transfer device and the sewing device in accordance with the pattern data that are corrected by the correction device. 
     Exemplary embodiments also provide a sewing machine that is included in a sewing system that, using a plurality of the sewing machines, performs sewing of a single embroidery pattern on a work cloth that is held by an embroidery frame. The sewing machine includes a transfer device, a sewing device, an image capture device, a condition acquisition device, a data acquisition device, a computation device, a correction device, and a sewing control device. The transfer device includes a carriage to which the embroidery frame can be attached and the transfer device is adapted to transfer the carriage. The sewing device moves a needle bar, to a bottom end of which a needle is attached, up and down. The image capture device is adapted to capture at least one image of at least one marker that is positioned in a marker area. The marker area is on at least one of the embroidery frame that is attached to the carriage and the work cloth that is held by the embroidery frame. The condition acquisition device acquires a pattern condition that is a condition for specifying at least one partial pattern among a plurality of partial patterns that form the embroidery pattern as a whole. The at least one partial pattern is allocated to the sewing machine. The data acquisition device acquires pattern data that are data for sewing the at least one partial pattern that is specified by the pattern condition and that is allocated to the sewing machine. The computation device computes, as a positioning condition, at least one of a reference position and a reference angle of the at least one marker in relation to the carriage, based on image data that are generated by the image capture device. The correction device sets a position and an angle of the partial pattern in relation to the carriage and corrects the pattern data that are acquired by the data acquisition device based on the positioning condition that is computed by the computation device. The sewing control device performs sewing of the partial pattern by controlling the transfer device and the sewing device in accordance with the pattern data that are corrected by the correction device. 
     Exemplary embodiments also provide a computer-readable medium storing a control program executable on a sewing machine that is included in a sewing system that, using a plurality of the sewing machines, performs sewing of a single embroidery pattern on a work cloth that is held by an embroidery frame. The program includes instructions that cause a controller of the sewing machine to perform the steps of acquiring a pattern condition and a setting condition, the pattern condition being a condition for specifying at least one partial pattern among a plurality of partial patterns that form the embroidery pattern as a whole, the at least one partial pattern being allocated to the sewing machine, and the setting condition being a condition for specifying a position and an angle of the embroidery pattern in relation to at least one marker, acquiring pattern data that are data for sewing the at least one partial pattern that is specified by the pattern condition and that is allocated to the sewing machine, computing, as a positioning condition, based on image data that are generated by an image capture device that captures at least one image of at least one marker that is positioned in a marker area, at least one of a reference position and a reference angle of the at least one marker, in relation to a carriage to which the embroidery frame is removably attached, the marker area being on at least one of the embroidery frame that is attached to the carriage and the work cloth that is held by the embroidery frame, setting a position and an angle of the partial pattern in relation to the carriage, based on the positioning condition and the setting condition, and correcting the pattern data, and performing the sewing of the partial pattern by controlling a transfer device and a sewing device in accordance with the corrected pattern data, the transfer device including the carriage and being adapted to transfer the carriage, and the sewing device that being adapted to move a needle bar, to a bottom end of which a needle is attached, up and down. 
     Exemplary embodiments further provide a computer-readable medium storing a control program executable on a sewing machine that is included in a sewing system that, using a plurality of the sewing machines, performs sewing of a single embroidery pattern on a work cloth that is held by an embroidery frame. The program includes instructions that cause a controller of the sewing machine to perform the steps of acquiring a pattern condition that is a condition for specifying at least one partial pattern among a plurality of partial patterns that form the embroidery pattern as a whole, the at least one partial pattern being allocated to the sewing machine, acquiring pattern data that are data for sewing the at least one partial pattern that is specified by the pattern condition and that is allocated to the sewing machine, computing, as a positioning condition, based on image data that are generated by an image capture device that captures at least one image of at least one marker that is positioned in a marker area, at least one of a reference position and a reference angle of the at least one marker, in relation to a carriage to which the embroidery frame is removably attached, the marker area being on at least one of the embroidery frame that is attached to the carriage and the work cloth that is held by the embroidery frame, setting a position and an angle of the partial pattern in relation to the carriage, based on the positioning condition, and correcting the pattern data, and performing the sewing of the partial pattern by controlling a transfer device and a sewing device in accordance with the corrected pattern data, the transfer device including the carriage and being adapted to transfer the carriage, and the sewing device that being adapted to move a needle bar, to a bottom end of which a needle is attached, up and down. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments will be described below in detail with reference to the accompanying drawings in which: 
         FIG. 1  is a conceptual diagram of a sewing system  100  that is provided with a plurality of multi-needle sewing machines  1 ; 
         FIG. 2  is an oblique view of the multi-needle sewing machine  1 ; 
         FIG. 3  is an oblique view that shows an interior of a needle bar case  21 ; 
         FIG. 4  is a plan view of an embroidery frame moving mechanism  11 ; 
         FIG. 5  is a block diagram that shows an electrical configuration of the multi-needle sewing machine  1 ; 
         FIG. 6  is an explanatory figure of a marker  180 ; 
         FIG. 7  is an explanatory figure of a sewing screen  200  that is displayed on a liquid crystal display  7 ; 
         FIG. 8  is an explanatory figure for explaining a position of an embroidery pattern  202  in relation to the marker  180 ; 
         FIG. 9  is a flowchart of main processing; 
         FIG. 10  is an explanatory figure of processing that detects the marker  180  based on image data of the marker  180  that are captured and acquired; 
         FIG. 11  is an explanatory figure of the processing that detects the marker  180  based on the image data of the marker  180  that are captured and acquired; 
         FIG. 12  is an explanatory figure for explaining the position of the embroidery pattern  202  in relation to the marker  180  in a case where the position has been altered; 
         FIG. 13  is an explanatory figure for explaining the position of the embroidery pattern  202  in relation to an X carriage  22 ; 
         FIG. 14  is an explanatory figure of history data; 
         FIG. 15  is a plan view of an embroidery frame moving mechanism  311  in a modified embodiment; 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a multi-needle sewing machine (hereinafter simply called the sewing machine)  1  that is an embodiment will be explained with reference to the drawings. The referenced drawings are used for explaining technical features that may be utilized in the present disclosure, and the device configurations and the like that are described are simply explanatory examples that do not limit the present disclosure to only those configurations and the like. 
     First, a sewing system  100  will be explained with reference to  FIG. 1 . The sewing system  100  includes two sewing machines  1 . The two sewing machines  1  are connected by a USB cable  147  that is connected to connectors  9  that will be described later (refer to  FIGS. 2 and 5 ). The physical configurations and the electrical configurations are the same between the two sewing machines  1 . 
     The physical configuration of the sewing machine  1  will be explained with reference to  FIGS. 2 and 3 . In the explanation that follows, in  FIG. 2 , the lower left side, the upper right side, the upper left side, and the lower right side of the page respectively indicate the front side, the rear side, the left side, and the right side of the sewing machine  1 . 
     The sewing machine  1  is provided with a supporting portion  2 , a pillar  3 , and an arm  4 . The supporting portion  2  is formed in an inverted U shape in a plan view, and the supporting portion  2  supports the entire sewing machine  1 . A pair of left and right guide slots  25  that extend in the front-to-rear direction are provided on the top face of the supporting portion  2 . The pillar  3  is provided such that it rises upward from the rear portion of the supporting portion  2 . The arm  4  extends forward from the upper end of the pillar  3 . A needle bar case  21  is mounted on the front end of the arm  4  such that the needle bar case  21  can move to the left and to the right. The needle bar case  21  will be described in detail later. 
     An operation portion  6  is provided on the right side of the arm  4  at a central position in the front-to-rear direction. A vertically extending shaft (not shown in the drawings) serves as an axis of rotation on which the operation portion  6  is pivotally supported by the arm  4 . The operation portion  6  is provided with a liquid crystal display (hereinafter simply called the LCD)  7 , a touch panel  8 , and connectors  9 . An operation screen for a user to input commands, for example, may be displayed on the LCD  7 . The touch panel  8  may be used to accept commands from the user. The user can select various types of conditions relating to a sewing pattern and sewing by using a finger, a stylus pen or the like to perform a pressing operation (the operation hereinafter being called a panel operation) on a location on the touch panel  8  that corresponds to a position on a screen that is displayed on the LCD  7  and that shows an input key or the like. The connectors  9  are USB standard connectors, and a USB device  160  (refer to  FIG. 5 ) can be connected to them. 
     A cylindrical cylinder bed  10  that extends forward from the bottom end of the pillar  3  is provided underneath the arm  4 . A shuttle (not shown in the drawings) is provided in the interior of the front end of the cylinder bed  10 . A bobbin (not shown in the drawings) on which a lower thread (not shown in the drawings) is wound may be accommodated in the shuttle. A shuttle drive mechanism (not shown in the drawings) is also provided in the interior of the cylinder bed  10 . The shuttle drive mechanism rotationally drives the shuttle. A needle plate  16  that is rectangular in a plan view is provided on the top face of the cylinder bed  10 . A needle hole  36  through which a needle  35  passes is provided in the needle plate  16 . 
     An embroidery frame moving mechanism  11  is provided underneath the arm  4 . The sewing machine  1  performs sewing of an embroidery pattern on a work cloth  39  that is held by an embroidery frame  84  as the embroidery frame  84  is moved to the left and the right, and forward and backward, by an X axis motor  132  (refer to  FIG. 5 ) and a Y axis motor  134  (refer to  FIG. 5 ) of the embroidery frame moving mechanism  11 . The embroidery frame moving mechanism  11  will be described in detail later. 
     A right-left pair of spool platforms  12  are provided at the rear face side of the top face of the arm  4 . Three thread spool pins  14  are provided on each of the spool platforms  12 . The thread spool pins  14  are pins that extend in the vertical direction. The thread spool pins  14  support thread spools  13 . The number of the thread spools  13  that can be placed on the one pair of the spool platforms  12  is six, the same as the number of needle bars  31 . Upper threads  15  may be supplied from the thread spools  13  that are attached to the spool platforms  12 . Each of the upper threads  15  may be supplied, through a thread guide  17 , a tensioner  18 , and a thread take-up lever  19 , to an eye (not shown in the drawings) of each of the needles  35  that are attached to the bottom ends of the needle bars  31  respectively. 
     Next, an internal mechanism of the needle bar case  21  will be explained with reference to  FIG. 3 . As shown in  FIG. 3 , the six needle bars  31  that extend in the vertical direction are provided inside the needle bar case  21  at equal intervals X in the left-right direction. A needle bar number is assigned to each of the needle bars  31  in order to identify the individual needle bars  31 . In the present embodiment, the needle bar numbers  1  to  6  are assigned in order starting from the right side in  FIG. 3 . The needle bars  31  are supported by two upper and lower securing members (not shown in the drawings) that are secured to a frame  80  of the needle bar case  21 , such that the needle bars  31  can slide up and down. A needle bar follow spring  72  is provided on the upper half of each of the needle bars  31 , and a presser spring  73  is provided on the lower half of each of the needle bars  31 . A needle bar guide  79  is provided between the needle bar follow spring  72  and the presser spring  73 , and a presser guide  83  is provided below the presser spring  73 . The needle bars  31  are slid up and down by a needle bar drive mechanism  85 . The needle bar drive mechanism  85  includes a sewing machine motor  122  (refer to  FIG. 5 ), a thread take-up lever drive cam  75 , a coupling member  76 , a transmitting member  77 , a guide bar  78 , and a coupling pin (not shown in the drawings). The sewing machine motor  122  is a drive source for the needle bar drive mechanism  85 . The needles  35  (refer to  FIG. 2 ) may be attached to the bottom ends of the needle bars  31 . A presser foot  71  that extends from each of the presser guides  83  to slightly below the bottom end portion (the tip portion) of the corresponding needle  35 , and operates in conjunction with the up-and-down movement of the corresponding needle bar  31 , the presser foot  71  intermittently presses the work cloth  39  (refer to  FIG. 2 ) downward. 
     An image sensor holding mechanism  150  is attached to the lower portion of the right side face of the frame  80 . The image sensor holding mechanism  150  is provided with an image sensor  151 , a holder  152 , a supporting member  153 , and a connecting plate  154 . The image sensor  151  is a known complementary metal oxide semiconductor (CMOS) image sensor. The holder  152  supports the image sensor  151  in a state in which a lens (not shown in the drawings) of the image sensor  151  faces downward. The center of the lens of the image sensor  151  is in a position that is at a distance  2 × from the needle bar  31  that is the farthest to the right. The supporting member  153  has an L shape when viewed from the front, and the supporting member  153  supports the connecting plate  154  and the holder  152 . The supporting member  153  is secured to the lower portion of the right side face of the frame  80  by screws  156 . The holder  152  is secured to the bottom face of the supporting member  153  by a screw  157 . The connecting plate  154  is a plate that is L-shaped when viewed from the front, and the connecting plate  154  electrically connects the image sensor  151  to a control portion  140  that will be described later (refer to  FIG. 5 ). The connecting plate  154  is secured to the front face of the supporting member  153  by screws  155 . The front face, the top face, and the right side face of the image sensor holding mechanism  150  are covered by a cover  38  (refer to  FIG. 2 ). 
     A plate  41 , which extends in the right-to-left direction, is affixed to the rear edge of the upper portion of the frame  80 . Eight engaging rollers  42  are respectively mounted on the plate  41  from the rear side by shoulder bolts  44 . Each of the engaging rollers  42  has a round cylindrical shape that is not shown in detail in the drawings. The engaging rollers  42  are supported by shoulder bolts  44  such that the engaging rollers  42  may revolve and such that the engaging rollers  42  cannot move in the axial direction of the engaging rollers  42 . The shoulder bolts  44  are threaded into threaded holes (not shown in the drawings) in the plate  41  and secured. The tips of the shoulder bolts  44  (the tips of male threaded portions) are secured by nuts  43  such that the shoulder bolts  44  will not be loosened by the revolving of the engaging rollers  42 . The intervals between the central axis lines of the engaging rollers  42  are all the same as the intervals X between the needle bars  31 . The heights of mounted positions of the eight engaging rollers  42  are all the same. One of the eight engaging rollers  42  engages a helical cam (not shown in the drawings) that is provided in front portion of the arm  4 . The helical cam is rotated by a needle bar case motor  45  (refer to  FIG. 5 ) and moves the frame  80  (the needle bar case  21 ) to the left and to the right. The one of the needle bars  31  with the needle bar numbers  1  to  6  and the image sensor  151  that corresponds to the engaging roller  42  that engages the helical cam is positioned directly above the needle hole  36 . However, in a case where the engaging roller  42  that is the second from the right has engaged the helical cam, neither any of the needle bars  31  nor the image sensor  151  is positioned directly above the needle hole  36 . 
     Next, the embroidery frame  84  and the embroidery frame moving mechanism  11  will be explained with reference to  FIG. 4 . The embroidery frame  84  is provided with an outer frame  81 , an inner frame  82 , and a pair of left and right coupling portions  89 . The embroidery frame  84  holds the work cloth  39  between the outer frame  81  and the inner frame  82 . The coupling portions  89  are plate members that, in a plan view, have rectangular shapes in which rectangular center portions have been cut out. One of the coupling portions  89  is secured to the right portion of the inner frame  82  by screws  95 , and the other of the coupling portions  89  is secured to the left portion of the inner frame  82  by screws  94 . In addition to the embroidery frame  84 , a plurality of types of other embroidery frames that differ in both size and shape can also be mounted in the sewing machine  1 . Of the embroidery frames that can be used in the sewing machine  1 , the embroidery frame  84  is the embroidery frame with the greatest width in the left-right direction (the distance between the left and right coupling portions  89 ). A sewing area  86  is defined in a position that is inside the inner frame  82 , in accordance with the type of the embroidery frame  84 . 
     The embroidery frame moving mechanism  11  includes a holder  24 , an X carriage  22 , an X axis drive mechanism (not shown in the drawings), a Y carriage  23 , and a Y axis drive mechanism (not shown in the drawings). The holder  24  supports the embroidery frame  84  such that the embroidery frame  84  can be mounted and removed. The holder  24  is provided with an attaching portion  91 , a right arm portion  92 , and a left arm portion  93 . The attaching portion  91  is a plate member that is rectangular in a plan view, with its long sides running in the left-right direction. The right arm portion  92  is a plate member that extends in the front-rear direction and is secured to the right end of the attaching portion  91 . The left arm portion  93  is a plate member that extends in the front-rear direction. The left arm portion  93  is secured to the left portion of the attaching portion  91  in a position that can be adjusted in the left-right direction in relation to the attaching portion  91 . The right arm portion  92  is engaged with one of the coupling portions  89 , and the left arm portion  93  is engaged with the other of the coupling portions  89 . 
     The X carriage  22  is a plate member, with its long dimension running in the left-right direction, and a portion of the X carriage  22  projects forward from the front end of the Y carriage  23 . The attaching portion  91  of the holder  24  is attached to the X carriage  22 . The X axis drive mechanism includes the X axis motor  132  (refer to  FIG. 5 ) and a linear movement mechanism (not shown in the drawings). The X axis motor  132  is a stepping motor. The linear movement mechanism includes a timing pulley (not shown in the drawings) and a timing belt (not shown in the drawings), and the linear movement mechanism moves the X carriage  22  to the left and to the right (in the X axis direction) using the X axis motor  132  as its drive source. 
     The Y carriage  23  has a box shape, with its long dimension running in the left-right direction. The Y carriage  23  supports the X carriage  22  such that the X carriage  22  can move to the left and to the right. The Y axis drive mechanism includes a pair of left and right moving bodies  26  (refer to  FIG. 2 ), the Y axis motor  134  (refer to  FIG. 5 ), and a linear movement mechanism (not shown in the drawings). The moving bodies  26  are coupled to the bottom portions of the left and right ends of the Y carriage  23  respectively and pass vertically through the guide slots  25  (refer to  FIG. 2 ). The Y axis motor  134  is a stepping motor. The linear movement mechanism includes a timing pulley (not shown in the drawings) and a timing belt (not shown in the drawings), and the linear movement mechanism moves the moving bodies  26  forward and backward (in the Y axis direction) along the guide slots  25  using the Y axis motor  134  as its drive source. In conjunction with these movements, the Y carriage  23 , which is coupled to the moving bodies  26 , and the X carriage  22 , which is supported by the Y carriage  23 , move forward and backward (in the Y axis direction). 
     Next, the operation that forms a stitch on the work cloth  39  that is held by the embroidery frame  84  will be explained with reference to  FIGS. 2 to 5 . The embroidery frame  84  by which the work cloth  39  is held is supported by the holder  24  of the embroidery frame moving mechanism  11  (refer to  FIGS. 2 and 4 ). First, one of the six needle bars  31  is selected by the moving of the needle bar case  21  in the left-right direction. The embroidery frame  84  is moved to a specified position by the embroidery frame moving mechanism  11 . The needle bar drive mechanism  85  is driven when a main shaft  74  is rotated by the sewing machine motor  122 . The rotational movement of the main shaft  74  is transmitted to the coupling member  76  through the thread take-up lever drive cam  75 , and the transmitting member  77 , on which the coupling member  76  is pivotably supported, is driven up and down, being guided by the guide bar  78 , which is positioned parallel to the needle bar  31 . The up-and-down movement is transmitted to the needle bar  31  through the coupling pin (not shown in the drawings), and the needle bar  31 , to which the needle  35  is attached, is driven up and down. Through a link mechanism that is not shown in detail in the drawings, the thread take-up lever  19  is driven up and down by the rotation of the thread take-up lever drive cam  75 . Furthermore, the rotation of the main shaft  74  is transmitted to the shuttle drive mechanism (not shown in the drawings), and the shuttle (not shown in the drawings) is rotationally driven. Thus the needle  35 , the thread take-up lever  19 , and the shuttle are driven in synchronization, and a stitch is formed on the work cloth  39 . 
     Next, the electrical configuration of the sewing machine  1  will be explained with reference to  FIG. 5 . As shown in  FIG. 5 , the sewing machine  1  includes a needle drive portion  120 , a sewn object drive portion  130 , the operation portion  6 , the image sensor  151 , and the control portion  140 . The needle drive portion  120 , the sewn object drive portion  130 , the operation portion  6 , and the control portion  140  will each be described in detail below. 
     The needle drive portion  120  includes the sewing machine motor  122 , a drive circuit  121 , the needle bar case motor  45 , a drive circuit  123 , a cutting mechanism  126 , and a drive circuit  125 . The sewing machine motor  122  moves the needle bars  31  reciprocally up and down. The drive circuit  121  drives the sewing machine motor  122  in accordance with a control signal from the control portion  140 . The needle bar case motor  45  moves the needle bar case  21  to the left and to the right in relation to the body of the sewing machine  1 . The drive circuit  123  drives the needle bar case motor  45  in accordance with a control signal from the control portion  140 . The cutting mechanism  126  cuts the upper threads  15  (refer to  FIG. 2 ) that are supplied to the needles  35 . The drive circuit  125  drives the cutting mechanism  126  in accordance with a control signal from the control portion  140 . 
     The sewn object drive portion  130  includes the X axis motor  132 , a drive circuit  131 , the Y axis motor  134 , and a drive circuit  133 . The X axis motor  132  moves the embroidery frame  84  (refer to  FIG. 2 ) to the left and to the right. The drive circuit  131  drives the X axis motor  132  in accordance with a control signal from the control portion  140 . The Y axis motor  134  moves the embroidery frame  84  forward and backward. The drive circuit  133  drives the Y axis motor  134  in accordance with a control signal from the control portion  140 . 
     The operation portion  6  includes the touch panel  8 , the connectors  9 , a drive circuit  135 , and the LCD  7 . The drive circuit  135  drives the LCD  7  in accordance with a control signal from the control portion  140 . The connectors  9  are provided with functions that connect to the USB device  160 . The USB device  160  may be a personal computer, a USB memory, or another sewing machine  1 , for example. 
     The control portion  140  includes a CPU  141 , a ROM  142 , a RAM  143 , an EEPROM  144 , and an input/output interface (I/O)  146 , all of which are connected to one another by a bus  145 . The needle drive portion  120 , the sewn object drive portion  130 , the operation portion  6 , and the image sensor  151  are each connected to the I/O  146 . The CPU  141 , the ROM  142 , the RAM  143 , and the EEPROM  144  will be explained in detail below. 
     The CPU  141  conducts main control over the sewing machine  1  and, in accordance with various types of programs that are stored in a program storage area (not shown in the drawings) in the ROM  142 , executes various types of computations and processing that relating to sewing. The programs may also be stored in an external storage device such as a flexible disk or the like. 
     The ROM  142  is provided with a plurality of storage areas that include the program storage area and a pattern storage area, although these are not shown in the drawings. Various types of programs for operating the sewing machine  1 , including a main program, are stored in the program storage area. The main program is a program for executing main processing that will be described later. Embroidery data (pattern data) for sewing embroidery patterns (partial patterns) are stored in the pattern storage area in association with pattern IDs. The pattern IDs are used in processing that specifies an embroidery pattern. 
     The RAM  143  is a storage element that can be read from and written to as desired, and storage areas that store computation results and the like from computational processing by the CPU  141  are provided in the RAM  143  as necessary. The EEPROM  144  is a storage element that can be read from and written to as desired, and various types of parameters for the sewing machine  1  to execute various types of processing are stored in the EEPROM  144 . IDs for distinguishing the sewing machines  1  that are included in the sewing system  100  are also stored in the EEPROM  144 . The IDs can be assigned as desired and may be represented in the form of ten-digit manufacturing numbers, for example. In the present embodiment, the ID of the sewing machine  1  on the left side of  FIG. 1  (hereinafter called the first sewing machine  1 ) is  1000 , and the ID of the sewing machine  1  on the right side of  FIG. 1  (hereinafter called the second sewing machine  1 ) is  1100 . 
     Next, a marker  180  will be explained with reference to  FIG. 6 . The left, right, up, and down directions in  FIG. 6  respectively correspond to the left, right, up, and down directions in the marker  180 . The marker  180  may be affixed onto the top surface of the work cloth  39 . The marker  180  that is shown in  FIG. 6  is a thin, transparent base material sheet  96  that is rectangular in shape and measures three centimeters long by two centimeters wide. A pattern is drawn on one surface of the base material sheet  96 . Specifically, a first circle  101  and a second circle  102  are drawn on the base material sheet  96 . The second circle  102  is disposed above the first circle  101  and has a smaller diameter than does the first circle  101 . Line segments  103  to  105  are also drawn on the base material sheet  96 . The line segment  103  is a line segment that extends from the top edge to the bottom edge of the marker  180  and passes through a center  110  of the first circle  101  and a center  111  of the second circle  102 . The line segment  104  is a line segment that is orthogonal to the line segment  103  and passes through the center  110  of the first circle  101 , extending from the right edge to the left edge of the marker  180 . The line segment  105  is a line segment that is orthogonal to the line segment  103  and passes through the center  111  of the second circle  102 , extending from the right edge to the left edge of the marker  180 . 
     Of the four areas that are bounded by the perimeter of the first circle  101 , the line segment  103  and the line segment  104 , an upper right area  108  and a lower left area  109  are filled in with black, and a lower right area  113  and an upper left area  114  are filled in with white. Similarly, of the four areas that are bounded by the second circle  102 , the line segment  103  and the line segment  105 , an upper right area  106  and a lower left area  107  are filled in with black, and a lower right area  115  and an upper left area  116  are filled in with white. All other parts of the surface on which the pattern of the marker  180  is drawn are transparent. 
     The back surface of the marker  180  (the surface on which the pattern is not drawn) is coated with a transparent adhesive. When the marker  180  is not in use, a release paper (not shown in the drawings) is affixed to the back surface of the marker  180 . The user may peel the marker  180  off the release paper and affixes the marker  180  onto a marker area of the work cloth  39 . The marker area is a position onto which the marker  180  is affixed. The marker area may be anywhere, as long as the marker area is on at least one of the embroidery frame  84  that is attached to the X carriage  22  and the work cloth  39  that is held by the embroidery frame  84 . A predetermined position for the marker area may also be set, and the position may be set anywhere that is on at least one of the embroidery frame  84  that is attached to the X carriage  22  and the work cloth  39  that is held by the embroidery frame  84 . In the present embodiment, a marker area  87  and a marker area  88  that are shown in  FIG. 4  are set as the marker areas. The marker area  87  is set in a position that is adjacent to the coupling portion  89  on the left side, in an area between the inner frame  82  and the sewing area  86 , with its position in the front-to-rear direction being between the two screws  94 . The marker area  88  is set in a position that is adjacent to the coupling portion  89  on the right side, in an area between the inner frame  82  and the sewing area  86 , with its position in the front-to-rear direction being between the two screws  95 . 
     Next, the main processing that is executed in the sewing machine  1  included in the sewing system  100  will be explained using as an example a case in which an embroidery pattern  202  that is shown in  FIG. 7  is sewn. First, the embroidery pattern  202  will be explained with reference to  FIG. 7 . The embroidery pattern  202  is a pattern of a bird that is to be sewn using threads of six different colors. The embroidery pattern  202  includes partial patterns that are divided according to the thread color, that is, six partial patterns. The embroidery data for the embroidery pattern  202  include six pieces of pattern data. The pattern data are data for sewing the partial patterns. The embroidery pattern  202  is displayed in a pattern display area  201  on a sewing screen  200  that is displayed on the LCD  7 . The order in which the partial patterns are sewn is displayed in a sewing order display area  204 . As shown in the sewing order display area  204 , the partial patterns for the embroidery pattern  202  are supposed to be sewn in the order of white, blue, yellow, orange, red, and black. In a case where the embroidery pattern  202  will be sewn using the one sewing machine  1  that is displaying the sewing screen  200 , the colors of threads of the thread spools that should be attached to the sewing machine  1  are displayed in a thread spool display area  203  in association with the numbers of the needle bars  31 . The embroidery data (the pattern data) for the embroidery pattern  202  may be stored in one of the ROM  142 , the EEPROM  144 , and the USB device  160 , for example. The embroidery data (the pattern data) may also be acquired through an Internet connection, for example. 
     Next, the embroidery data (the pattern data) of the present embodiment will be explained. The embroidery data (the pattern data) of the present embodiment include data on coordinates in a marker coordinate system. The marker coordinate system is a coordinate system that is set based on the markers  180  that are positioned in the marker area  87  and the marker area  88 , as shown in  FIG. 8 . An Xm axis of the marker coordinate system passes through the center of the first circle  101  of the marker  180  that is positioned in the marker area  87  and through the center of the first circle  101  of the marker  180  that is positioned in the marker area  88 . A Ym axis of the marker coordinate system is orthogonal to the Xm axis and passes through a point on the Xm axis that is a specified distance to the right of the center of the first circle  101  of the marker  180  that is positioned in the marker area  87 . The specified distance is predetermined and is stored in the EEPROM  144 . An area  186  is a sewing area in the marker coordinate system. 
     The coordinate data in the marker coordinate system are converted into coordinate data in an embroidery coordinate system, based on coordinates of the markers  180  in the embroidery coordinate system, which are computed in the main processing that will be described later. The embroidery coordinate system is the coordinate system for the X axis motor  132  and the Y axis motor  134  that move the X carriage  22 . The coordinate data in the embroidery coordinate system describe the position and angle of the embroidery pattern (the partial pattern) in relation to the X carriage  22 . In the present embodiment, the embroidery coordinate system is made to correspond to the actual three-dimensional coordinate system (the world coordinate system) in advance. In the embroidery coordinate system, the left-right direction of the sewing machine  1  is an Xe axis direction, and the front-rear direction of the sewing machine  1  is a Ye axis direction. In the present embodiment, in a case where the embroidery frame  84  is properly attached to the X carriage  22 , the theoretical center of the sewing area  86  serves as an origin point (Xe, Ye, Ze)=(0, 0, 0) at a position that is congruent with a needle drop point. The needle drop point is the point where the needle  35  pierces the work cloth  39  when the corresponding needle bar  31  is moved downward from a state in which the needle  35  that is disposed directly above the needle hole  36  (refer to  FIG. 2 ) is above the work cloth  39 . In the present embodiment, the embroidery frame moving mechanism  11  does not move the X carriage  22  in a Ze direction (the up-down direction of the sewing machine  1 ), so as long as the thickness of the work cloth  39  can be ignored, the top surface of the work cloth  39  is deemed to have a Ze coordinate value of zero. 
     Next, an overview of the main processing that is executed in the sewing system  100  will be explained. In the main processing, the partial pattern that is allocated to the sewing machine  1  is sewn in the sewing order. Using the panel operation, the user may select the embroidery pattern, modify the placement of the selected embroidery pattern, and allocate the partial patterns. The user may allocate the partial patterns to the individual sewing machines  1 , taking into account the colors of the threads of the thread spools  13  that are attached to the individual sewing machines  1 . The main processing may be started in any one of the sewing machines  1  included in the sewing system  100 . The sewing machine  1  in which the main processing is started by an instruction from the user transmits a start command to the other sewing machine  1  included in the sewing system  100 . When the other sewing machine  1  receives the start command, the other sewing machine  1  starts the main processing. In other words, once the main processing is started in any one of the sewing machines  1 , the main processing is executed in all of the sewing machines  1  included in the sewing system  100 . As shown in  FIG. 1 , the colors of the threads of the thread spools  13  that are attached to the first sewing machine  1  are white, black, green, blue, sky blue, and yellow. The colors of the threads in the thread spools  13  that are attached to the second sewing machine  1  are greenish yellow, sky blue, red, orange, blue, and black. In the main processing, the positioning of the embroidery pattern (the partial pattern) is determined in each individual sewing machine  1 , based on images of the markers  180  affixed to the marker areas  87 ,  88 . 
     Next, the main processing in the sewing system  100  will be explained in more detail with reference to  FIG. 9 . The main processing in  FIG. 9  is executed by the CPU  141  in accordance with the main program that is stored in the ROM  142 . A case in which the main processing is started in the first sewing machine  1  will be explained as an example. 
     First, a message screen is displayed on the LCD  7  (Step S 5 ). A message is displayed on the message screen that prompts the user to input an image capture command after checking the two items that are described below. The first item is whether the embroidery frame  84  by which the work cloth  39  is held has been attached to the holder  24  of the embroidery frame moving mechanism  11 . The second item is whether the markers  180  have been placed in the marker area  87  and the marker area  88 . The positions of the marker area  87  and the marker area  88  are displayed on the message screen along with a schematic view of the embroidery frame  84 , although this is not shown in the drawings. The user checks the message screen and places the markers  180  in the marker area  87  and the marker area  88 . 
     Following the processing at Step S 5 , the CPU  141  waits for the image capture command to be input (NO at Step S 10 ), and in a case where the image capture command is input (YES at Step S 10 ), the image sensor  151  captures images of the markers  180  that are attached onto the work cloth  39  (Step S 15 ). The image capture command may be input by the panel operation, for example. At Step S 15 , a control signal is output to the drive circuit  123  (refer to  FIG. 5 ), and the needle bar case  21  is moved to the position where the helical cam (not shown in the drawings) engages the engaging roller  42  that is the farthest to the right. The image sensor  151  is positioned directly above the needle hole  36  by the moving of the needle bar case  21 . Next, control signals are output to the drive circuit  131  (refer to  FIG. 5 ) and the drive circuit  133  (refer to  FIG. 5 ), and the embroidery frame  84  is moved in accordance with the embroidery coordinate system coordinates of the marker area  87  that are stored in the EEPROM  144 . The marker area  87  is moved to a position directly below the image sensor  151  by the moving of the embroidery frame  84 . Next, an image of the marker  180  that is positioned in the marker area  87  is captured by the image sensor  151 , and the image data that have been thus generated are stored in the RAM  143 . In the same manner, an image of the marker  180  that is positioned in the marker area  88  is captured, and the image data that have been thus generated are also stored in the RAM  143 . 
     Next, a positioning condition is computed based on the image data that have been generated at Step S 15 , and the computed positioning condition is stored in the RAM  143  (Step S 20 ). The positioning condition is defined as at least one of a reference position and a reference angle related to the markers  180  in relation to the X carriage  22 , the positioning condition is computed based on at least one of the markers  180  represented by the image data that are generated by the image sensor  151 . In the present embodiment, the reference position that is described by the coordinate of the embroidery coordinate system and the reference angle in relation to the positive direction on the Xe axis are computed as the positioning condition. 
     The method for computing the positioning condition in the present embodiment will be explained with reference to  FIGS. 10 and 11 . First, two-dimensional coordinates in an image coordinate system are computed for the first circle  101  and the second circle  102  of the marker  180  (refer to  FIG. 6 ). The image coordinate system is a coordinate system for the image that has been captured by the image sensor  151 . The two-dimensional coordinates in the image coordinate system are computed based on a position in the image. Specifically, circumferences of a circle  161  and a circle  162  are identified in the captured image, as shown in  FIG. 10 , for example, by Hough transform processing, which is a known technique. The coordinates of a center  163  of the circle  161  and a center  164  of the circle  162 , and radii of the circle  161  and the circle  162  are computed. At this stage, a circle that is included in a pattern or the like of the work cloth  39  itself may be identified in addition to the first circle  101  and the second circle  102  of the marker  180 . Hereinafter, a number z of coordinates that are computed for a center of a circle are indicated as (a, b) (for example, (a1, b1), (a2, b2), (a3, b3), . . . , (az, bz)), and a radius that is computed for a circle is indicated as r (for example, r1, r2, r3, . . . , rz). 
     The image data are processed, with Harris operator, for example, which is a known technique, to compute coordinates 171 to 179 and 181 of corners, from the captured image, as shown in  FIG. 11 . The corner refers to an intersection point at which a plurality of edges (portions that are each formed of a line, such as a contour) intersect with each other. Hereinafter, the computed a number 10 of coordinates of the corners are indicated as (s, t) (for example, (s1, t1), (s2, t2), (s3, t3), (s10, s10)). 
     Next, the computation results for the coordinates (a, b) and the radii r are compared to the coordinates (s, t). In a case where a set of the coordinates (s, t) exists that coincides with one of the sets of the coordinates (a, b), and sets of the coordinates (s, t) exist that coincide with the coordinates of positions along one of the radii r whose midpoint is at one of the sets of the coordinates (a, b), a determination is made that the first set of the coordinates (s, t) are the coordinates of the center of one of the first circle  101  and the second circle  102  in  FIG. 11 , and the other sets of the coordinates (s, t) are the coordinates of points where a line segment intersects the circumference of one of the first circle  101  and the second circle  102 . Of the coordinates (a, b) that are the coordinates of the center of one of the first circle  101  and the second circle  102 , the coordinates that correspond to the center of the circle for which the value of the radius r is greater are identified as the coordinates (p, q) of the center of the first circle  101 . The coordinates that correspond to the center of the circle for which the value of the radius r is smaller are identified as the coordinates (u, v) of the center of the second circle  102 . The executing of the image processing that is described above causes the coordinates (p1, q1) of the center of the first circle  101  and the coordinates (u1, v1) of the center of the second circle  102  to be computed for the marker  180  that is positioned in the marker area  87 . The coordinates (p2, q2) of the center of the first circle  101  and the coordinates (u2, v2) of the center of the second circle  102  in the marker  180  that is positioned in the marker area  88  are computed in the same manner. 
     Next, three-dimensional coordinate conversion processing is executed on the center coordinates that have been computed. The three-dimensional coordinate conversion processing is processing that converts the two-dimensional coordinates of the image coordinate system into the three-dimensional coordinates of the embroidery coordinate system (the world coordinate system). The three-dimensional coordinate conversion processing may be executed using a known method. For example, Japanese Laid-Open Patent Publication No. 2009-172119 discloses the three-dimensional coordinate conversion processing, the relevant portions of which are herein incorporated by reference. In the three-dimensional coordinate conversion processing, the amount of movement of the embroidery frame  84  at Step S 15  is factored into the computation of the three-dimensional coordinates of the embroidery coordinate system. The execution of the three-dimensional coordinate conversion processing causes the coordinates (P1, Q1, R1) of the center of the first circle  101  and the coordinates (U1, V1, W1) of the center of the second circle  102  to be computed for the marker  180  that is positioned in the marker area  87 . The coordinates (P2, Q2, R2) of the center of the first circle  101  and the coordinates (U2, V2, W2) of the center of the second circle  102  in the marker  180  that is positioned in the marker area  88  are computed in the same manner. 
     Next, the reference position and the reference angle are computed. The reference position is defined as the coordinates (P1, Q1, R1) of the center of the first circle  101  in the marker  180  that is positioned in the marker area  87 , as expressed in the embroidery coordinate system. The reference angle θ is defined as the angle, in relation to the positive direction on the Xe axis of the embroidery coordinate system, of a vector from the coordinates (P1, Q1, R1) to the coordinates (P2, Q2, R2) of the center of the first circle  101  in the marker  180  that is positioned in the marker area  88 . As described previously, the embroidery coordinate system is the coordinate system that is defined for moving the X carriage  22 , so the reference position and the reference angle express the position and the angle in relation to the X carriage  22 , respectively. The marker  180  that is positioned in the marker area  87  and the marker  180  that is positioned in the marker area  88  are differentiated by taking into consideration the coordinates of the centers of the second circles  102  in relation to the centers of the first circles  101  and the positioning of the markers  180  in the embroidery frame  84 . The reference angle θ indicates the angle of rotation of the axes of the marker coordinate system that have been converted into the embroidery coordinate system, in relation to the axes of the embroidery coordinate system. The reference angle θ expresses, as a positive value, the angle of counterclockwise rotation around the origin point of the embroidery coordinate system. In the present embodiment, the Ze coordinate of a point on the work cloth  39  is defined as having a (fixed) value of zero, so the reference angle θ is computed using the equation θ=tan −1 ((Q2−Q1)/(P2−P1)). 
     Following the processing at Step  20 , a determination is made as to whether history data have been received through the USB cable  147  and the connectors  9  (Step S 25 ). The history data are data that are transmitted through the USB cable  147  from the other sewing machine  1  that has been used before the sewing machine  1  in interest. The history data will be described in detail later. 
     The processing in a case where the history data have been received (YES at Step S 25 ) will be described later. In a case where the history data have not been received (NO at Step S 25 ), a determination is made as to whether a pattern condition has been input (Step S 30 ). The pattern condition is a condition that includes at least a condition for specifying at least one partial pattern that has been allocated to the sewing machine  1  in interest from among the plurality of the partial patterns that form the embroidery pattern as a whole. In the present embodiment, the pattern condition is information that is input in order to specify the partial patterns that are allocated to each of the sewing machines  1  that will be used for sewing the embroidery pattern, the information being input on the sewing machine  1  that will be the first to be used. Specifically, at Step S 30 , a condition that includes both the pattern ID that specifies the embroidery pattern and the information that specifies the partial patterns that will be allocated to each of the sewing machines  1  are input as the pattern condition on the sewing machine  1  that will be the first to be used. Therefore, the pattern condition that is input at Step S 30  includes a condition for specifying the partial patterns that will be allocated to the sewing machine  1  that will be the first to be used and a condition for specifying the partial patterns that will be allocated to the other sewing machine  1 . At Step S 30 , in a case where both the pattern ID that specifies the embroidery pattern and the information that specifies the partial patterns that will be allocated to each of the sewing machines  1  included in the sewing system  100  have been input by the panel operation, a determination is made that the pattern condition has been input (YES at Step S 30 ). In a case where the pattern condition has not been input (NO at Step S 30 ), the processing returns to Step S 25 . In the processing at Step S 30 , assume a specific example in which the pattern ID of the embroidery pattern  202  in  FIG. 7  has been input as the pattern ID. In this specific example, it is assumed that the first to the third partial patterns in the sewing order have been allocated to the first sewing machine  1  and that the fourth to the sixth partial patterns in the sewing order have been allocated to the second sewing machine  1 . In a case where the pattern condition has been input (YES at Step S 30 ), the pattern condition that has been input are acquired, and the acquired pattern condition are stored in the RAM  143  (Step S 35 ). 
     Next, the pattern data are acquired from the ROM  142  in accordance with the condition that specifies at least one of the partial patterns that have been allocated to the sewing machine  1  and that is included in the pattern condition that has been acquired at Step S 35 . The acquired pattern data are stored in the RAM  143  (Step S 40 ). In the case of the specific example that is described above, the pattern data that correspond to the first to the third partial patterns in the sewing order are acquired in the first sewing machine  1 . Next, a determination is made as to whether the positioning of the embroidery pattern has been changed (Step S 45 ). A command to change the positioning may be input by the panel operation. In the present embodiment, the sewing machine  1  is capable of changing the settings for the position of the embroidery pattern, which is expressed in the marker coordinate system, and changing the angle in relation to the initial positioning. The coordinates of the marker coordinate system are used for changing the positioning. In a case where the positioning of the embroidery pattern has been changed (YES at Step S 45 ), an amount of movement (ΔMx, ΔMy) of a first reference point in relation to the initial positioning and an angle of rotation ω of the embroidery pattern expressed in the marker coordinate system are acquired as a setting condition, and the acquired setting condition is stored in the RAM  143  (Step S 50 ). The setting condition is a condition for specifying the position and the angle of the embroidery pattern in relation to the markers  180 . The initial positioning of the embroidery pattern is defined by the coordinate data in the pattern data that have been acquired at Step S 40 . The first reference point is determined as appropriate, and a hypothetical point that coincides with the origin point prior to the change in the positioning may be used, for example. The angle of rotation ω expresses, as a positive value, the angle in a case where the embroidery pattern has been rotated counterclockwise around the first reference point. At Step S 50 , assume a specific example as shown in  FIG. 12 , in which, after the embroidery pattern  202  has been rotated fifteen degrees counterclockwise around the origin point, the embroidery pattern  202  is moved 25 units in the positive direction of the Xm axis and 25 units in the positive direction of the Ym axis. In this specific example, the amount of movement (ΔMx, ΔMy) of the hypothetical point is acquired as (25, 25), and the angle of rotation ω is acquired as fifteen degrees. 
     Following the processing at Step S 50 , as well as in a case where the positioning has not been changed (NO at Step S 45 ), the pattern data are corrected, and the corrected pattern data are stored in the RAM  143  (Step S 70 ). At Step S 70 , the pattern data that have been acquired at Step S 40  are corrected based on the positioning condition that has been computed at Step S 20  and on the setting condition that has been acquired at Step S 50 . First, the pattern data are corrected based on the setting condition that has been acquired at Step S 50 . The correcting is processing for changing the positioning of the at least one of the partial patterns that have been allocated to the sewing machine  1  in the pattern coordinate system, in accordance with the setting condition. In a case where the positioning of the embroidery pattern has not been changed, the setting condition is set such that (ΔMx, ΔMy) are (0, 0) and the angle of rotation ω is zero degrees. The coordinate data that are included in the pattern data are defined as (x, y). The coordinate data (x, y) are corrected based on the setting condition, and coordinate data (x′, y′) are computed by the correcting processing. In a case where the previously described hypothetical point is defined as the first reference point, the coordinate data (x′, y′) are computed based on the equation (x′, y′)=(x cos ω−y sin ω+ΔMx, x sin ω+y cos ω+ΔMy). Next, the coordinate data (x′, y′) are corrected based on the positioning condition that has been computed at Step S 20 , and coordinate data (x″, y″) are computed by the correcting processing. The correcting is processing for converting the coordinate data in the pattern coordinate system into the coordinate data in the embroidery coordinate system. In a case where the previously described hypothetical point is defined as the first reference point, the coordinate data (x″, y″) are computed based on the equation (x″, y″)=((x′−bx)cos θ−(y′−by)sin θ+bx+Δmx, (x′−bx)sin θ+(y′−by)cos θ+by+Δmy). (bx, by) are the coordinates of a second reference point in the embroidery coordinate system. The coordinates of the second reference point in the embroidery coordinate system theoretically coincide with the coordinates of the second reference point in the marker coordinate system. (Δmx, Δmy) indicate the difference between the coordinates of the second reference point in the embroidery coordinate system and the coordinates of the second reference point in the marker coordinate system that have been converted to the embroidery coordinate system based on the three-dimensional coordinates of the markers  180 . The origin point of the marker coordinate system and the origin point of the embroidery coordinate system, for example, may be used as the second reference point. For example, in a case where the embroidery data are corrected using the equation described above on the condition under which the reference angle θ is acquired as −1 degree and (Δmx, Δmy)=(5, −5), the embroidery pattern  202  is positioned in the position that is shown in  FIG. 13 . In a case where the positioning of the embroidery pattern has not been changed at Step S 45 , the coordinate data (x″, y″) may also be computed using (x, y) instead of (x′, y′). In  FIG. 13 , the portion of the area  186  that overlaps the sewing area  86  is the area where the sewing can be performed using the sewing machine  1 . In a case where the embroidery pattern includes an outer portion that is positioned outside the sewing area  86 , it is not possible for the sewing machine  1  to sew the outer portion, so the area  186  may be set in advance to be smaller than the sewing area  86 . 
     Next, a determination is made as to whether a command to start the sewing has been input (Step S 75 ). The command to start the sewing may be input by the panel operation, for example. In a case where the command to start the sewing has not been input (NO at Step S 75 ), the CPU  141  waits until the command to start the sewing is input. In a case where the command to start the sewing has been input (YES at Step S 75 ), the at least one partial pattern is sewn in accordance with the pattern data that have been corrected at Step S 70  (Step S 80 ). Specifically, a control signal is output to the drive circuit  123  in accordance with the pattern data, and the needle bar case motor  45  is driven. This causes the needle  35  to which thread of the thread spool  13  (refer to  FIG. 2 ) is supplied that has the color that corresponds to the pattern data to be positioned directly above the needle hole  36 . Control signals are also output to the drive circuit  131  and the drive circuit  133  in accordance with the pattern data, and the embroidery frame  84  is moved. A control signal is also output to the drive circuit  121 , and the sewing machine motor  122  is driven. This causes the needle bar  31  that is positioned directly above the needle hole  36  to move in the up and down directions. The processing at Step S 80  causes the first to the third partial patterns in the sewing order to be sewn by the first sewing machine  1 . The thread spools  13  for the first to the third thread colors in the sewing order (white, blue, yellow) have been attached to the first sewing machine  1 . Therefore, at Step S 80 , the sewing is performed continuously, without interruption, with the threads being switched for the first to the third partial patterns in the sewing order. 
     Next, the history data are transmitted through the connectors  9  and the USB cable  147  to the next sewing machine  1  that will be used (Step S 85 ). The setting condition and a condition that specifies at least one partial pattern that is allocated to the next sewing machine  1  that will be used are included in the history data. As described previously, in the present embodiment, the setting condition may be, for example, the amount of movement (ΔMx, ΔMy) and the angle of rotation ω of the embroidery pattern in comparison to the initial positioning of the embroidery pattern as expressed in the marker coordinate system. The condition for specifying the at least one partial pattern that is allocated to the next sewing machine  1  includes the pattern ID for specifying the embroidery pattern, as well as a starting point (START) and an ending point (END) in the sewing order for the at least one partial pattern that is allocated to the next sewing machine  1  that will be used. In the specific example, at Step S 85 , first, the second sewing machine  1  is specified as the next sewing machine  1  that will be used, based on the pattern condition that has been acquired at Step S 35 . At Step S 85 , the history data are generated as shown in  FIG. 14 , with the history data including the setting condition that has been acquired at Step S 50  and the conditions for specifying the at least one partial pattern that is allocated to the second sewing machine  1 , which have been included in the pattern condition that has been acquired at Step S 35 . The history data in  FIG. 14  include the pattern ID, the START, and the END, as the condition for specifying the at least one partial pattern that is allocated to the second sewing machine  1 , and the amount of movement (ΔMx, ΔMy) and the angle of rotation ω as the setting condition. The history data are transmitted to the second sewing machine  1  through the connectors  9  and the USB cable  147 . Following the processing at Step S 85 , the main processing is terminated. 
     At Step S 25 , in a case where the history data have been received through the connectors  9  and the USB cable  147  (YES at Step S 25 ), the received history data are acquired as the pattern condition and the setting condition, and the acquired conditions are stored in the RAM  143  (Step S 60 ). Hereinafter, assume a case in which the main processing is executed in the second sewing machine  1 . At Step S 60 , the history data that have been transmitted at Step S 85 , which has been executed by the first sewing machine  1 , are acquired as the pattern condition and the setting condition. The pattern ID, the START, and the END that are included in the history data are acquired as the pattern condition for the second sewing machine  1 . Next, the pattern data are acquired based on the conditions that have been acquired as the pattern condition at Step S 60 , and the acquired pattern data are stored in the RAM  143  (Step S 65 ). At Step S 65 , the pattern data are acquired for the fourth to the sixth partial patterns in the sewing order of the embroidery pattern  202 . Next, the pattern data that have been acquired at Step S 65  are corrected based on the positioning condition that has been computed at Step S 20  and on the setting condition that has been included in the history data that have been acquired at Step S 60 , and the corrected pattern data are stored in the RAM  143  (Step S 70 ). The method of correcting the pattern data is the same as that described earlier. Next, in a case where the command to start the sewing has been input (YES at Step S 75 ), the fourth to the sixth partial patterns in the sewing order are sewn in accordance with the pattern data that have been corrected at Step S 70  (Step S 80 ). The thread spools  13  for the fourth to the sixth thread colors in the sewing order (orange, red, black) have been attached to the second sewing machine  1 . Therefore, at Step S 80 , the sewing is performed continuously, without interruption, with the threads being switched for the fourth to the sixth partial patterns in the sewing order. Next, because the second sewing machine  1  is the last of the sewing machines  1  to be used, the processing at Step S 85  is omitted, and the main processing is terminated. 
     In the sewing system  100 , the position and the angle of the partial pattern can be set in relation to the X carriage  22  in each of the plurality of the sewing machines  1 , based on the markers  180  that are positioned in the marker area  87  and the marker area  88 . Therefore, even in a case where the positions where the embroidery frame  84  is attached or the settings of the embroidery coordinate systems varies among the plurality of the sewing machines  1 , it is possible to avoid a situation in which the relative positioning of the partial patterns that are sewn in the plurality of the sewing machines  1  is unintentionally changed. Therefore, each of the sewing machines  1  included in the sewing system  100  can accurately sew the embroidery pattern  202  together with the other sewing machines  1 . Because the sewing machine  1  uses the two markers  180  to compute the reference angle θ, the sewing machine  1  can compute the reference angle θ more precisely than in a case where only one marker is used. Therefore, the sewing machine  1 , by using the markers  180  that are positioned in the marker area  87  and the marker area  88  as references, can set the position and the angle of the partial pattern in relation to the X carriage  22  more accurately than in a case where only one marker is used in computing the reference angle θ. The pattern data can be corrected to match the position and the angle of the embroidery pattern that are specified by the setting condition. In the sewing machines  1  that will be used second and later, the setting condition is acquired from the history data that are received at Step S 25 , so the time and effort that are required for the user to input the setting condition to the individual sewing machines  1  can be eliminated. Furthermore, it is possible to avoid a situation in which the relative positioning of the partial patterns that are sewn in the plurality of the sewing machines  1  is unintentionally changed due to a mistake by the user in inputting the setting condition to the individual sewing machines  1 . The time and effort that are required for the user to input the pattern condition to the individual sewing machines  1  can be eliminated in the same manner. It is possible to avoid a situation in which an incorrect partial pattern is sewn due to a mistake by the user in inputting the pattern condition to the individual sewing machines  1 . In addition, because the bottom surfaces of the markers  180  are coated with a transparent adhesive, the markers  180  can be used by affixing them onto the work cloth  39 . In a case where the markers  180  are no longer needed after the sewing is completed, the user can easily peel the markers  180  off the work cloth  39 . The user can also easily change the positions where the markers  180  are affixed onto the work cloth  39 . 
     The sewing system of the present disclosure is not limited to the embodiment that is described above, and various types of modifications may be made within the scope of the present disclosure. For example, the modifications that are described below from (A) to (II) may be made as desired. 
     (A) The number of the sewing machines  1  that are included in the sewing system  100  is not limited to being two and may be any number that is at least two. The number of the needle bars that are provided in the sewing machine  1  may be one and may also be more than one. In a case where the sewing machines  1  included in the sewing system  100  are capable of communicating with one another, the communication devices and the method of connecting them can be modified as desired. For example, a plurality of the sewing machines  1  may communicate wirelessly. In a case where a plurality of the sewing machines  1  are connected by wire, they may be connected by a LAN cable for example, instead of by a USB cable. In the sewing system  100  that is described above, a plurality of the sewing machines  1  are provided that have the same physical configuration and the same electrical configuration, but a plurality of the sewing machines  1  may also be provided that have different physical configurations and different electrical configurations. In that ease, it shall be possible to attach the same embroidery frame in the plurality of the sewing machines  1 , and the all of the sewing machines  1  shall be capable of sewing in accordance with the same embroidery data. 
     (B) The configuration of the sewing machine  1  can be modified as desired. For example, the type and the positioning of the image sensor  151  may be modified as desired. The image sensor  151  may also be an image capture element other than a CMOS image sensor, such as a CCD camera or the like, for example. The direction in which the embroidery frame moving mechanism  11  moves the X carriage  22 , for example, can also be modified as desired. 
     (C) The embroidery pattern that is sewn by the sewing system  100  may also be modified in various ways. For example, an aggregation of a plurality of patterns may also serve as a single pattern. In addition, the setting condition for the marker coordinate system can also be modified as desired, for example, as long as the coordinate data in the pattern data are data in which the positioning of the embroidery pattern in relation to the markers  180  is defined. The specified distance that defines the position of the Ym axis may also be input by the panel operation, for example. The setting condition for the embroidery coordinate system can also be modified as desired. 
     (D) The sizes and shapes of the markers, the design of the markers, the number of the markers, and the marker areas can each be set as desired. The design of the markers may be any design that makes it possible to specify the markers based on the image data of the markers that are captured and acquired. For example, the colors with which the upper right area  108 , the lower left area  109 , and the like of the markers  180  are filled in are not limited to being white and black, and any other combination of colors that provides a clear contrast may also be used. The markers may also be modified according to the color and the pattern of the work cloth  39 , for example. 
     The number of the markers may also be defined as desired, taking into consideration the precision of the positioning of the partial pattern and the time that is required for executing the main processing. In a case where the number of the markers is greater than one, the plurality of the markers may all be of the same type, and they may also be of a plurality of types. The marker area may also be on at least one of the embroidery frame  84  that is attached to the X carriage  22  and the work cloth  39  that is held by the embroidery frame  84 . The marker areas may also be defined in advance, as in the present embodiment, and may be positioned anywhere on the work cloth  39 , for example. In a case where the marker area is defined in advance, the processing that specifies the markers based on the image data is simpler than in a case where the position of the marker area is defined as desired. 
     Furthermore, for example, as in a modified embodiment that is shown in  FIG. 15 , the markers may also be positioned in an embroidery frame  384 . In  FIG. 15 , the same reference numerals are assigned in the same sort of configuration as that of the embroidery frame moving mechanism  11  in  FIG. 4 . As shown in  FIG. 15 , a marker  282  on which the first circle  101  is drawn and a marker  281  on which the second circle  102  is drawn may also be used. In this case, the marker  281  and the marker  282  may be distinguished by the sizes of the circles. As in  FIG. 15 , the marker area may also be set in coupling portions  389  of the embroidery frame  384 . In a case where the markers  281 ,  282  are drawn on the embroidery frame  384 , as in  FIG. 15 , it is possible in the sewing machine  1  for the time and effort that are required for the user to place the markers in the marker areas to be eliminated and to reliably avoid a situation in which the markers are placed in positions that are not in the marker areas. 
     (E) The method of acquiring the pattern condition can also be modified as desired. For example, Japanese Laid-Open Patent Publication No. 2009-22400 discloses a method for allocating the partial patterns to the individual sewing machines  1  automatically, the relevant portions of which are herein incorporated by reference. In the sewing machines  1  that will be used second and later, the conditions that are included in the history data that are transmitted from the sewing machine  1  that has been used immediately prior to the sewing machine  1  in interest are acquired as the pattern conditions, but the user may also input the pattern condition to the individual sewing machine  1  in which the partial pattern will be sewn, for example. A pattern condition that is stored in an external storage device such as a memory card or the like, for example, may also be acquired. In this case, the sewing machine  1  does not need to have a communication device. The content of the pattern condition may also be modified as desired. Furthermore, in a sewing system in which the condition is set such that the partial pattern that is sewn can be sewn without the thread spools being changed, for example, the sewing order numbers of the partial patterns for which the sewing has already been completed (hereinafter called the completed numbers) may be defined in the pattern condition. In that case, the sewing machine  1  that has acquired the completed numbers may set as the at least one partial pattern to be sewn at least one partial pattern whose sewing order number is at least one greater than the highest of the completed numbers and that can be sewn without the thread spools  13  being changed. This makes it possible to eliminate the time and effort that are required for the user to allocate the partial patterns to the individual sewing machines  1  while taking into consideration the colors of the threads of the thread spools  13  that are attached to the sewing machines  1 . 
     (F) The content of the setting condition and the method for acquiring the setting condition may also be modified as desired. For example, in the sewing machines  1  that will be used second and later, the setting condition may also be input by the panel operation. Moreover, in a case where the positioning of the embroidery pattern is not changed in relation to the initial positioning, the position and the angle in relation to the X carriage  22  may also be set based on the initial positioning, for example. In that case, the setting condition does not need to be acquired. A rate of enlargement or reduction of the embroidery pattern may also be set along with the setting condition, for example. In that case, the pattern data may be corrected in accordance with the set rate of enlargement or reduction. 
     (G) The positioning condition may also include one of the position and the angle of the marker in relation to the X carriage  22 . For example, in a case where the positioning condition is only the position of the marker, the angle of the partial pattern is not corrected according to the positioning condition at Step S 70 . In that case, the angle of the partial pattern is set based on the initial position of the partial pattern that is defined by the coordinate data in the pattern data and on the setting condition that is acquired at Step S 50  (Step S 60 ). Similarly, in a case where the positioning condition is only the angle of the marker, the position of the partial pattern is set based on the initial position of the partial pattern and on the setting condition. The method for computing the positioning condition, for example, may also be modified as desired, in accordance with the positioning condition and the markers. For example, in a case where the angle is computed as a part of the positioning condition, based on the image data for one of the markers  180 , the angle may also be computed based on the coordinates of the center of the first circle  101  and the coordinates of the center of the second circle  102 . As another example, in a case where the position is computed as a part of the positioning condition, based on the image data for two of the markers  180 , the midpoint of a line segment that connects the centers of the first circles  101  of the two markers  180  may be computed as the position of the marker. 
     (H) At Step S 85  in  FIG. 9 , the method by which the sewing machine  1  transmits the history data to the next sewing machine  1  that will be used can be modified as desired. For example, history data that include associations between the partial patterns and the IDs of the sewing machines  1  may also be transmitted to all of the sewing machines  1  that are included in the sewing system  100 . In that case, the sewing machines  1  that have received the history data may specify the partial patterns that are associated with their own IDs, based on the received history data. In a case where the sewing system  100  includes two sewing machines  1 , as it is in the present embodiment, for example, the sewing machine  1  that has performed the sewing may set the other sewing machine  1  as the sewing machine  1  that will be used next. To take another example, the sewing machine  1  may also specify the sewing machine  1  that will be used next, in accordance with one of the pattern condition that is acquired at Step S 35  and the history data that are acquired at Step S 60 , and then transmit the history data to the specified sewing machine  1 . The content of the history data may also be modified as desired. 
     The apparatus and methods described above with reference to the various embodiments are merely examples. It goes without saying that they are not confined to the depicted embodiments. While various features have been described in conjunction with the examples outlined above, various alternatives, modifications, variations, and/or improvements of those features and/or examples may be possible. Accordingly, the examples, as set forth above, are intended to be illustrative. Various changes may be made without departing from the broad spirit and scope of the underlying principles.