Patent Publication Number: US-9897380-B2

Title: Carrier transport system

Description:
CROSS REFERENCE 
     This application is a division of and is based upon and claims the benefit of priority under 35 U.S.C. § 120 for U.S. Ser. No. 13/061,873, filed Mar. 2, 2011, the entire contents of which is incorporated herein by reference. U.S. Ser. No. 13/061,873 is a National Stage of PCT/IB09/006837, filed Sep. 8, 2009, and claims the benefit of priority under 35 U.S.C. § 119 from Japanese Patent Application No. 2008-231932, filed Sep. 10, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a technique for positioning carriers, which are transported by a transport conveyor, in a heating furnace. 
     2. Description of the Related Art 
     Various techniques have been suggested for positioning work or a carrier transported by a transport conveyor. For example, Japanese Utility Model Publication No. 1-15199 (JP-Y-1-15199) describes a technique for positioning first one substrate by a positioning mechanism when a plurality of substrates (work) in a transport path are transported by a comb-shaped guide member having a plurality of protrusions and then the first one substrate in the transport direction reaches a predetermined position. The positioning mechanism positions a substrate using, for example, a block equipped with a piston and rollers provided at a distal end of a cylinder for guiding a substrate. 
     In addition, various techniques have been suggested for checking whether positioning is accurately performed. For example, Japanese Patent Publication No. 2-49856 (JP-B-2-49856) describes a technique for checking whether there is a pallet on a swiveling table. In the technique, positioning means for positioning a pallet by fitting a movable pin in a recess formed in the pallet and detecting means for detecting whether the movable pin is fitted in the recess of the pallet are provided. In this technique, one pallet is positioned by the positioning means, and then completion of the positioning may be checked by the detecting means. 
     However, the techniques described in JP-Y-1-15199 and JP-B-2-49856 have the following problems. That is, according to the technique described in JP-Y-1-15199, it is not checked whether a substrate is accurately positioned after the substrate has been positioned. Therefore, if the substrate is not accurately positioned because, for example, work gets caught on something, it may be impossible to, for example, process or treat the work appropriately. 
     In addition, in the technique described in JP-B-2-49856, completion of positioning is checked by the detecting means; however, this technique is not directed to simultaneously positioning a plurality of pallets and then checking the positioning of the plurality of pallets, there is still a problem that working efficiency is poor. 
     SUMMARY OF THE INVENTION 
     The invention provides a carrier positioning method and carrier transport system that are able to simultaneously position a plurality of carriers in a heating furnace and then check whether all the carriers are accurately positioned with a simple configuration. 
     A first aspect of the invention provides a carrier positioning method that transports a plurality of carriers, on which pieces of work are respectively mounted, by a transport conveyor into a heating furnace and that positions the plurality of carriers. The carrier positioning method includes: a transport process of transporting the plurality of carriers by the transport conveyor into the heating furnace; a first advance process of advancing a comb-shaped carrier stopper toward the carriers, wherein the carrier stopper has a plurality of protrusions used for positioning the carriers; a positioning process of positioning the carriers at a time at predetermined intervals in a transport direction in which the carriers are transported in such a manner that the carriers are moved by the transport conveyor in the transport direction to engage engagement portions, provided respectively for the carriers, with the protrusions of the carrier stopper; a second advance process of advancing the carrier stopper toward the carriers so as to insert distal ends of the respective protrusions of the carrier stopper into insertion holes of the engagement portions, wherein the insertion holes are provided so as to allow the distal ends of the protrusions to be inserted when the carriers are properly positioned; and a determination process of determining, on the basis of a moved distance of the carrier stopper toward the carriers, whether the carriers are properly positioned. 
     In the carrier positioning method according to the first aspect of the invention, the “positioning process” may be performed after the “first advance process” has been completed; instead, the “first advance process” and the “positioning process” may be performed in parallel with each other. In addition, in the carrier positioning method, the carriers may be once stopped after the “first advance process” has been completed and then the carriers may be advanced in the “second advance process” again; instead, the “first advance process” and the “second advance process” may be continuously performed. In addition, the “moved distance of the carrier stopper” may be a total moved distance of a moved distance in the “first advance process” and a moved distance in the “second advance process”; instead, the “moved distance of the carrier stopper” may be only a moved distance in the “second advance process”. 
     In the carrier positioning method according to the first aspect of the invention, in the transport process, the plurality of carriers are transported by the transport conveyor into the heating furnace. Then, in the first advance process, the carrier stopper is advanced toward the carriers. By so doing, the plurality of protrusions of the carrier stopper may be moved to positions at which the protrusions are engageable with the engagement portions of the respective carriers. In addition, in the positioning process, the transport conveyor is moved in the transport direction to engage the plurality of protrusions of the carrier stopper with the engagement portions of the respective carriers. By so doing, the carriers may be positioned at intervals corresponding to the intervals of the protrusions of the carrier stopper. That is, in the above method, by changing the intervals of the protrusions of the carrier stopper, it is possible to position the carriers at desired positions. For example, when the carriers are positioned so that the carriers respectively face a plurality of heating devices provided in the heating furnace, it is possible to accurately heat pieces of work mounted respectively on the carriers by the heating devices without waste. 
     In the second advance process, the carrier stopper is advanced toward the carriers to cause the distal ends of the protrusions of the carrier stopper to be inserted into the insertion holes provided for the engagement portions of the respective carriers. The insertion holes are provided so as to allow the distal ends of the protrusions to be inserted when the carriers are properly positioned. Then, in the determination process, it is determined, on the basis of the moved distance of the carrier stopper, whether the carriers are properly positioned. Here, determination as to whether the carriers are properly positioned may, for example, include an embodiment in which it is determined that the carriers are properly positioned when the moved distance of the carrier stopper exceeds a predetermined reference value, and it is determined that the carriers are not properly positioned when the moved distance of the carrier stopper is smaller than or equal to the predetermined reference value. The reference value may be, for example, a moved distance of the carrier stopper at the time when the distal ends of the protrusions start to be inserted into the insertion holes. 
     In this manner, by determining whether the carriers are properly positioned, even when the carriers are not accurately positioned because, for example, the carriers get caught on something, it is possible to detect the inaccurate positioning and then position the carriers again. By so doing, it is possible to, for example, appropriately process or treat pieces of work mounted respectively on the carriers. In addition, the plurality of carriers may be positioned at a time and then the positioning may be checked, so working efficiency is favorable. 
     In addition, with the carrier positioning method according to the first aspect of the invention, a moved distance of the carrier stopper is detected to check whether positioning is accurately performed. Thus, a plurality of position detecting means (position sensors, or the like) corresponding to the respective carriers are not required. That is, even when the plurality of carriers are positioned in the heating furnace, it is not necessary to ensure a large space in the chamber side surface of the heating furnace to form a plurality of quartz windows. As a result, it is possible to position the plurality of carriers in the heating furnace at a time and to check whether all the carriers are positioned accurately with a simple configuration. 
     In addition, in the carrier positioning method according to the first aspect, the engagement portions of the carriers may be cutout grooves that are wider in the transport direction of the carriers than the protrusions, in the first advance process, the carrier stopper may be advanced toward the carriers to insert the protrusions of the carrier stopper into the cutout grooves, and in the positioning process, the carriers may be moved by the transport conveyor in the transport direction to engage rear end surfaces in the transport direction of the cutout grooves with the protrusions of the carrier stopper, whereby the carriers are positioned. 
     In this way, the engagement portions are formed of cutout grooves that are wider in the transport direction of the carriers than the protrusions. Thus, the protrusions of the carrier stopper may be inserted into the cutout grooves, and the carriers may be transported to engage the rear end surfaces in the transport direction of the cutout grooves with the protrusions of the carrier stopper. Therefore, it is possible to easily implement the carrier positioning method according to the first aspect. That is, it is possible to position the plurality of carriers in the heating furnace at a time with a simple configuration. 
     In addition, in the carrier positioning method according to the first aspect, the insertion holes may be provided at rear end portions in the transport direction of the respective cutout grooves, and, in the determination process, it may be determined, on the basis of the moved distance of the carrier stopper toward the carriers after the carriers have been moved in the transport direction in the positioning process, whether the carriers are properly positioned. 
     In addition, in the carrier positioning method according to the first aspect, the insertion holes may be provided at rear end portions in the transport direction of the respective cutout grooves, and, in the determination process, it may be determined that the carriers are not properly positioned when the moved distance of the carrier stopper toward the carriers is smaller than or equal to a predetermined reference value. 
     In addition, in the carrier positioning method according to the first aspect, when it is determined in the determination process that the carriers are not properly positioned, the carriers may be positioned again. 
     A second aspect of the invention provides a carrier transport system. The carrier transport system includes: a plurality of carriers on which pieces of work are respectively mounted; a transport conveyor that transports the plurality of carriers; a heating furnace that covers part of the transport conveyor and that heats the pieces of work; and positioning means that positions the plurality of carriers in the heating furnace, wherein the heating furnace includes a plurality of heating devices for heating the pieces of work inside so that the plurality of heating devices are arranged at predetermined intervals in a transport direction in which the carriers are transported, each of the carriers has at least one engagement portion, and the positioning means includes a comb-shaped carrier stopper having a plurality of protrusions that are engageable with the engagement portions of the respective carriers; actuating means that moves the carrier stopper toward the carriers in order to engage the protrusions with the engagement portions; moved distance detecting means that detects a moved distance of the carrier stopper moved by the actuating means; and determination means that determines, on the basis of the moved distance detected by the moved distance detecting means, whether the carriers are properly positioned. 
     Here, the “moved distance of the carrier stopper” may be a total moved distance of a moved distance in the “first advance process” and a moved distance in the “second advance process” as in the case of the above; instead, the “moved distance of the carrier stopper” may be only a moved distance in the “second advance process”. 
     In the carrier transport system according to the second aspect, the plurality of carriers are transported by the transport conveyor into the heating furnace. The plurality of heating devices for heating pieces of work are arranged in the heating furnace at predetermined intervals in the transport direction of the carriers. Then, after the carriers have been transported into the heating furnace, the carrier stopper is advanced toward the carriers by the actuating means, and then the carriers are moved by the transport conveyor in the transport direction. By so doing, it is possible to engage the plurality of protrusions of the carrier stopper with the engagement portions of the respective carriers. As a result, it is possible to position the carriers at intervals corresponding to the intervals of the protrusions of the carrier stopper. Here, in the carrier transport system according to the second aspect, by changing the intervals of the protrusions of the carrier stopper, it is possible to position the carriers at desired positions. Thus, by positioning the carriers so that the carriers respectively face the plurality of heating devices provided in the heating furnace, it is possible to accurately heat pieces of work mounted respectively on the carriers by the heating devices without waste. Note that in the carrier transport system according to the second aspect, the carriers may be positioned after the carrier stopper has been once advanced; instead, the carriers may be positioned while the carrier stopper is being advanced. 
     Then, in the carrier transport system according to the second aspect, it may be determined by the determination means on the basis of a moved distance of the carrier stopper whether the carriers are properly positioned. Note that, as in the case of the above, “determination as to whether the carriers are properly positioned” may, for example, include an embodiment in which it is determined that the carriers are properly positioned when the moved distance of the carrier stopper exceeds a predetermined reference value, and it is determined that the carriers are not properly positioned when the moved distance of the carrier stopper is smaller than or equal to the predetermined reference value. In this manner, by determining whether the carriers are properly positioned, even when the carriers are not accurately positioned because, for example, the carriers get caught on something, it is possible to detect the inaccurate positioning and then position the carriers again. By so doing, it is possible to, for example, appropriately process or treat pieces of work mounted respectively on the carriers. In addition, the plurality of carriers may be positioned at a time and then the positioning may be checked, so working efficiency is favorable. 
     In addition, with the carrier transport system according to the second aspect, a moved distance of the carrier stopper is detected to check whether positioning is accurately performed. Thus, a plurality of position detecting means (position sensors, or the like) corresponding to the respective carriers are not required. That is, even when the plurality of carriers are positioned in the heating furnace, it is not necessary to ensure a large space in the chamber side surface of the heating furnace to form a plurality of quartz windows. As a result, it is possible to position the plurality of carriers in the heating furnace at a time and to check whether all the carriers are positioned accurately with a simple configuration. 
     In the carrier transport system according to the second aspect, the engagement portions of the carriers may be cutout grooves that are wider in the transport direction of the carriers than the protrusions, rear end portions in the transport direction of the cutout grooves may respectively have insertion holes that allow distal ends of the protrusions to be inserted, and the actuating means may advance the carrier stopper so as to engage the protrusions with the cutout grooves and insert the distal ends of the protrusions into the insertion holes in coordination with transport operation of the transport conveyor. 
     In addition, in the carrier transport system according to the second aspect, after the protrusions are moved by the actuating means to be inserted into the cutout grooves, the transport conveyor may be transported to engage the rear end surfaces in the transport direction of the cutout grooves of the carriers with the protrusions, and then the protrusions may be moved by the actuating means toward the carriers again to insert the distal ends of the protrusions into the insertion holes. 
     In addition, the carrier transport system according to the second aspect may further include: a proximity detection sensor that detects proximity of the carriers; and control means that controls the actuating means to drive the carrier stopper on the basis of information detected by the proximity detection sensor. 
     With the carrier transport system according to the second aspect, the proximity of the carriers transported by the transport conveyor is detected by the proximity detection sensor, and it is possible to accurately determine that the carriers are transported to the predetermined positions on the basis of the detected information. Thus, the carrier stopper may be advanced toward the carriers at an adequate timing. As a result, it is possible to prevent interference between the carrier stopper and the carriers and accurately position the carriers. 
     In the carrier transport system according to the second aspect, the engagement portion of each carrier may be provided at each end in a direction that intersects with the transport direction, and the carrier stopper may be provided on each side in a direction that intersects with the transport direction. 
     In this way, the engagement portion of each carrier is provided at each end in a direction that intersects with the transport direction, and the carrier stopper is provided on each side in a direction that intersects with the transport direction. Thus, it is possible to position the carriers from both sides with respect to the transport direction. By so doing, it is possible to further accurately position the carriers. 
     In the carrier transport system according to the second aspect, the actuating means may advance at least one of the carrier stoppers, located on both sides, toward the carriers to hold the carriers by the carrier stoppers located on both sides. 
     In this way, the actuating means advances at least one of the carrier stoppers, located on both sides, toward the carriers to hold the carriers by the carrier stoppers located on both sides. Thus, it is possible to position the carriers in the direction that intersects with the transport direction. Thus, the pieces of work mounted respectively on the carriers may be further accurately arranged so that the pieces of work respectively face the heating devices in the heating furnace. As a result, the pieces of work may be further adequately heated without waste. 
     In the carrier transport system according to the second aspect, at least one of the carrier stoppers located on both sides may further include a rotation preventing portion that contacts parts of the carriers to prevent rotation of the carriers. 
     With the carrier transport system according to the second aspect, when the carriers rotate, the carriers contact the rotation preventing portion that is provided for at least one of the carrier stoppers located on both sides. Thus, rotation of the carriers is suppressed. Thus, the pieces of work mounted respectively on the carriers may be further accurately arranged so that the pieces of work respectively face the heating devices in the heating furnace. As a result, the pieces of work may be further adequately heated without waste. 
     With the carrier positioning method or the carrier transport system according to the aspect of the invention, as described above, it is possible to simultaneously position a plurality of carriers in a heating furnace and then check whether all the carriers are accurately positioned with a simple configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features, advantages, and technical and industrial significance of this invention will be described in the following detailed description of example embodiments of the invention with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is a cross-sectional view that shows the schematic configuration of a carrier transport system according to a first embodiment of the invention; 
         FIG. 2  is a plan view that shows the inside of the carrier transport system according to the first embodiment of the invention; 
         FIG. 3  is an enlarged view that shows a transport conveyor provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 4  is a perspective view that shows the transport conveyor provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 5  is a plan view that shows a carrier provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 6A  is a side cross-sectional view of a jig placed on a mount portion provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 6B  is a top view of the jig placed on the mount portion provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 7A  is a side cross-sectional view of a solder foil and element that are arranged on the mount portion provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 7B  is a top view of the solder foil and element that are arranged on the mount portion provided for the carrier transport system according to the first embodiment of the invention; 
         FIG. 8  is a view that illustrates a first step of positioning carriers according to the first embodiment of the invention; 
         FIG. 9  is a view that illustrates a second step of positioning the carriers according to the first embodiment of the invention; 
         FIG. 10  is a view that illustrates a third step of positioning the carriers according to the first embodiment of the invention; 
         FIG. 11  is a view that illustrates a fourth step of positioning the carriers according to the first embodiment of the invention; 
         FIG. 12  is a view that illustrates a fifth step of positioning the carriers according to the first embodiment of the invention; 
         FIG. 13  is a side view that shows a state where the carriers are positioned by carrier stoppers according to the first embodiment of the invention; 
         FIG. 14  is a schematic configuration diagram that shows a carrier transport system according to a second embodiment of the invention; 
         FIG. 15  is a schematic configuration diagram that shows a carrier transport system according to a third embodiment of the invention; 
         FIG. 16  is a view that illustrates a method of positioning carriers according to a comparative embodiment of the invention; 
         FIG. 17  is a view that illustrates the method of positioning carriers according to the comparative embodiment of the invention; and 
         FIG. 18  is a view that illustrate the method of positioning the carriers according to the comparative embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a carrier positioning method and carrier transport system according to aspects of the invention will be schematically described, and specific embodiments of the carrier positioning method and carrier transport system will be described. 
     First, the carrier positioning method according to a first aspect of the invention will be schematically described. The carrier positioning method according to the first aspect of the invention transports a plurality of carriers, on which pieces of work are respectively mounted, by a transport conveyor into a heating furnace and positions the plurality of carriers. The carrier positioning method includes: a transport process of transporting the plurality of carriers by the transport conveyor into the heating furnace; a first advance process of advancing a comb-shaped carrier stopper toward the carriers, wherein the carrier stopper has a plurality of protrusions used for positioning the carriers; a positioning process of positioning the carriers at a time at predetermined intervals in a transport direction in which the carriers are transported in such a manner that the carriers are moved by the transport conveyor in the transport direction to engage engagement portions, provided respectively for the carriers, with the protrusions of the carrier stopper; a second advance process of advancing the carrier stopper toward the carriers so as to insert distal ends of the respective protrusions of the carrier stopper into insertion holes of the engagement portions, wherein the insertion holes are provided so as to allow the distal ends of the protrusions to be inserted when the carriers are properly positioned; and a determination process of determining, on the basis of a moved distance of the carrier stopper toward the carriers, whether the carriers are properly positioned. 
     In the carrier positioning method according to the first aspect of the invention, the “positioning process” may be performed after the “first advance process” has been completed; instead, the “first advance process” and the “positioning process” may be performed in parallel with each other. In addition, in the carrier positioning method, advance of the carriers may be once stopped after the “first advance process” has been completed and then the carriers may be advanced in the “second advance process” again; instead, the “first advance process” and the “second advance process” may be continuously performed. In addition, the “moved distance of the carrier stopper” may be a total moved distance of a moved distance in the “first advance process” and a moved distance in the “second advance process”; instead, the “moved distance of the carrier stopper” may be only a moved distance in the “second advance process”. 
     In the carrier positioning method according to the first aspect of the invention, in the transport process, the plurality of carriers are transported by the transport conveyor into the heating furnace. Then, in the first advance process, the carrier stopper is advanced toward the carriers. By so doing, the plurality of protrusions of the carrier stopper may be moved to positions at which the protrusions are engageable with the engagement portions of the respective carriers. In addition, in the positioning process, the transport conveyor is moved in the transport direction to engage the plurality of protrusions of the carrier stopper with the engagement portions of the respective carriers. By so doing, the carriers may be positioned at intervals corresponding to the intervals of the protrusions of the carrier stopper. That is, in the above method, by changing the intervals of the protrusions of the carrier stopper, it is possible to position the carriers at desired positions. For example, when the carriers are positioned so that the carriers respectively face a plurality of heating devices provided in the heating furnace, it is possible to accurately heat pieces of work mounted respectively on the carriers by the heating devices without waste. 
     In the second advance process, the carrier stopper is advanced toward the carriers to cause the distal ends of the protrusions of the carrier stopper to be inserted into the insertion holes provided for the engagement portions of the respective carriers. The insertion holes are provided so as to allow the distal ends of the protrusions to be inserted when the carriers are properly positioned. Then, in the determination process, it is determined, on the basis of the moved distance of the carrier stopper, whether the carriers are properly positioned. Here, determination as to whether the carriers are properly positioned may, for example, include an embodiment in which it is determined that the carriers are properly positioned when the moved distance of the carrier stopper exceeds a predetermined reference value, and it is determined that the carriers are not properly positioned when the moved distance of the carrier stopper is smaller than or equal to the predetermined reference value. The reference value may be, for example, a moved distance of the carrier stopper at the time when the distal ends of the protrusions start to be inserted into the insertion holes. 
     In this manner, by determining whether the carriers are properly positioned, even when the carriers are not accurately positioned because, for example, the carriers get caught on something, it is possible to detect the inaccurate positioning and then position the carriers again. By so doing, it is possible to, for example, appropriately process or treat pieces of work mounted respectively on the carriers. In addition, the plurality of carriers may be positioned at a time and then the positioning may be checked, so working efficiency is favorable. 
     On the other hand, as shown in  FIG. 16 , the inventors have an idea (comparative embodiment) that there is provided a plurality of carriers  140  on which pieces of work  150  are respectively mounted, transport conveyors  120  that transport the plurality of carriers  140 , comb-shaped carrier stoppers  135  having a plurality of protrusions  135   a  for positioning the carriers  140  at predetermined intervals, cylinders  137  and position sensors  145  that detect a position of a first one carrier  140   a , and then the protrusions  135   a  of the carrier stoppers  135  are respectively engaged with cutout grooves  142  formed in the carriers  140  to position the plurality of carriers  140  at a time at the predetermined intervals. 
     In this technique, as shown in  FIG. 17 , by transporting the carriers  140  by the transport conveyors  120 , it is possible to engage the protrusions  135   a  of the carrier stoppers  135  with rear end surfaces  142   b  in the transport direction of the cutout grooves  142  of the respective carriers  140 . By so doing, it is possible to position the carriers  140  at the predetermined intervals. Then, the position of the first one carrier  140   a  is checked by the position sensors  145  to make it possible to check whether the carriers  140  are positioned. However, according to the above technique, as shown in  FIG. 18 , when a carrier  140   b , for example, gets caught on something, the rear end surfaces  142   b  of the cutout grooves  142  of the carrier  140   b  may not accurately engage with the protrusions  135   a  of the carrier stoppers  135 . That is, the carrier  140   b  may not be positioned accurately. Therefore, in the above technique, it may be difficult to accurately detect whether all the carriers  140  are accurately positioned. 
     On the other hand, it is also conceivable that a plurality of position sensors  145  are provided in correspondence with the respective carriers  140  to check whether the carriers  140  are positioned. However, in this case, the configuration of the system is complex and, in addition, it is necessary to ensure a space for providing the plurality of position sensors  145 . Particularly, when the plurality of carriers are positioned in the heating furnace, it is difficult to ensure a large space in the chamber side surfaces of the heating furnace. In addition, even when a sufficient space may be ensured in the chamber side surfaces of the heating furnace, it is necessary to form a plurality of quartz windows in the chamber side surfaces. This makes the configuration of the system complex to increase manufacturing cost. 
     In contrast, with the carrier positioning method according to the first aspect of the invention, it is impossible to insert the distal end of the protrusion of the carrier stopper into the insertion hole of the carrier that is not properly positioned, so the carrier stopper cannot be advanced toward the carriers until all the carriers are positioned accurately. Thus, different from the comparative embodiment, even when only one of the carriers is inaccurately positioned, it is possible to detect that the carrier is not positioned accurately. That is, it is possible to determine whether all the carriers are properly positioned accurately. 
     Next, a carrier transport system according to a second aspect of the invention will be schematically described. The carrier transport system according to the second aspect of the invention includes: a plurality of carriers on which pieces of work are respectively mounted; a transport conveyor that transports the plurality of carriers; a heating furnace that covers part of the transport conveyor and that heats the pieces of work; and positioning means that positions the plurality of carriers in the heating furnace, wherein the heating furnace includes a plurality of heating devices for heating the pieces of work inside so that the plurality of heating devices are arranged at predetermined intervals in a transport direction in which the carriers are transported, each of the carriers has at least one engagement portion, and the positioning means includes a comb-shaped carrier stopper having a plurality of protrusions that are engageable with the engagement portions of the respective carriers; actuating means that moves the carrier stopper toward the carriers in order to engage the protrusions with the engagement portions; moved distance detecting means that detects a moved distance of the carrier stopper moved by the actuating means; and determination means that determines, on the basis of the moved distance detected by the moved distance detecting means, whether the carriers are properly positioned. 
     Here, the “moved distance of the carrier stopper” may be a total moved distance of a moved distance in the “first advance process” and a moved distance in the “second advance process” as in the case of the above; instead, the “moved distance of the carrier stopper” may be only a moved distance in the “second advance process”. 
     In the carrier transport system according to the second aspect, the plurality of carriers are transported by the transport conveyor into the heating furnace. The plurality of heating devices for heating pieces of work are arranged in the heating furnace at predetermined intervals in the transport direction of the carriers. Then, after the carriers have been transported into the heating furnace, the carrier stopper is advanced toward the carriers by the actuating means, and then the carriers are moved by the transport conveyor in the transport direction. By so doing, it is possible to engage the plurality of protrusions of the carrier stopper with the engagement portions of the respective carriers. As a result, it is possible to position the carriers at intervals corresponding to the intervals of the protrusions of the carrier stopper. Here, in the carrier transport system according to the second aspect, by changing the intervals of the protrusions of the carrier stopper, it is possible to position the carriers at desired positions. Thus, by positioning the carriers so that the carriers respectively face the plurality of heating devices provided in the heating furnace, it is possible to accurately heat pieces of work mounted respectively on the carriers by the heating devices without waste. Note that in the carrier transport system according to the second aspect, the carriers may be positioned after the carrier stopper has been once advanced; instead, the carriers may be positioned while the carrier stopper is being advanced. 
     Then, in the carrier transport system according to the second aspect, it may be determined by the determination means on the basis of a moved distance of the carrier stopper whether the carriers are properly positioned. Note that, as in the case of the above, “determination as to whether the carriers are properly positioned” may, for example, include an embodiment in which it is determined that the carriers are properly positioned when the moved distance of the carrier stopper exceeds a predetermined reference value, and it is determined that the carriers are not properly positioned when the moved distance of the carrier stopper is smaller than or equal to the predetermined reference value. In this manner, by determining whether the carriers are properly positioned, even when the carriers are not accurately positioned because, for example, the carriers get caught on something, it is possible to detect the inaccurate positioning and then position the carriers again. By so doing, it is possible to, for example, appropriately process or treat pieces of work mounted respectively on the carriers. In addition, the plurality of carriers may be positioned at a time and then the positioning may be checked, so working efficiency is favorable. 
     In addition, with the carrier transport system according to the second aspect, a moved distance of the carrier stopper is detected to check whether positioning is accurately performed. Thus, a plurality of position detecting means (position sensors, or the like) corresponding to the respective carriers are not required. That is, even when the plurality of carriers are positioned in the heating furnace, it is not necessary to ensure a large space in the chamber side surface of the heating furnace to form a plurality of quartz windows. As a result, it is possible to position the plurality of carriers in the heating furnace at a time and to check whether all the carriers are positioned accurately with a simple configuration. 
     In the carrier transport system according to the second aspect, the engagement portions of the carriers may be cutout grooves that are wider in the transport direction of the carriers than the protrusions, rear end portions in the transport direction of the cutout grooves may respectively have insertion holes that allow distal ends of the protrusions to be inserted, and the actuating means may advance the carrier stopper so as to engage the protrusions with the cutout grooves and insert the distal ends of the protrusions into the insertion holes in coordination with transport operation of the transport conveyor. 
     In this way, by forming the cutout grooves of the carriers so as to be wider in the transport direction of the carriers than the protrusions of the carrier stopper, it is possible to easily insert the protrusions into the cutout grooves when the carrier stopper is advanced toward the carriers. In addition, by forming the insertion holes, which allow the distal ends of the protrusions to be inserted, at the rear end portions in the transport direction of the cutout grooves, it is possible to further advance the carrier stopper toward the carriers to insert the distal ends of the protrusions into the insertion holes in a state where the carriers are positioned so that the protrusions are engaged with the rear end surfaces in the transport direction of the cutout grooves. With the above configuration, it is possible to easily determine, on the basis of a moved distance of the carrier stopper, whether the carriers have been positioned. Specifically, with the above system, it is impossible to insert the distal end of the protrusion of the carrier stopper into the insertion hole that is not properly positioned. Therefore, the carrier stopper cannot be advanced toward the carriers unless all the carriers are positioned accurately. Thus, different from the comparative embodiment, even when only one of the carriers is inaccurately positioned, it is possible to detect that the carrier is not positioned accurately. That is, it is possible to position the plurality of carriers in the heating furnace at a time and to check whether all the carriers are positioned accurately with a simple configuration. 
     Hereinafter, specific embodiments of the carrier positioning method and carrier transport system according to the aspect of the invention will be described in detail with reference to the accompanying drawings. The carrier positioning method and the carrier transport system position carriers transported by a transport conveyor into a heating furnace and then heat pieces of work mounted respectively on the carriers. 
     A carrier transport system according to a first embodiment will be described with reference to  FIG. 1 .  FIG. 1  is a cross-sectional view that shows the schematic configuration of the carrier transport system according to the first embodiment of the invention. As shown in  FIG. 1 , the carrier transport system  10  includes carriers  40  on which pieces of work  50  are respectively mounted, transport conveyors  20  that transports the carriers  40 , a heating furnace  13  that covers part of the transport conveyors  20  and heats the pieces of work  50 , and a positioning mechanism (an example of the positioning means according to the aspect of the invention) that positions the plurality of carriers  40  in the heating furnace  13 . 
     The heating furnace  13  includes a chamber  17 , which forms a furnace body, and halogen heaters  30  (an example of the heating device according to the aspect of the invention) that respectively heat the pieces of work  50 . The inside of the chamber  17  is partitioned by a quartz glass  11  into an upper space and a lower space. Then, the space above the quartz glass  11  is a heating chamber  16 , and the space below the quartz glass  11  is a decompression chamber  15 . The heating chamber  16  is filled with inert gas, such as nitrogen. The plurality of halogen heaters  30  for heating the pieces of work  50  are provided in the decompression chamber  15  at predetermined intervals. For example, in the present embodiment, six halogen heaters  30  (not illustrated in the drawing) are provided in the heating furnace  13  at equal intervals in the transport direction of the carriers. Then, the carriers  40  are positioned by the positioning mechanism, which will be described later, so that the carriers  40  respectively face the halogen heaters  30 . That is, the carrier transport system  10  according to the present embodiment is able to handle six pieces of work at a time inside the heating furnace  13 . Note that the number of pieces of work handled in the heating furnace  13  is determined on the basis of a relationship between the size of the heating furnace  13  and the size of each piece of work  50 , so the number of pieces of work handled may be changed by changing the design where necessary. However, heating process requires several minutes, so the number of pieces of work handled is desirably increased as much as possible to improve working efficiency. 
     Each halogen heater  30  is a typical halogen heater in which a quartz glass tube is filled with halogen gas and a tungsten filament is provided in the quartz glass tube. The halogen heaters  30  are used to irradiate infrared rays to the pieces of work  50  to make it possible to heat the pieces of work  50 . The halogen heaters  30  are fixed in the decompression chamber  15 . On the other hand, the transport conveyors  20  are provided in the heating chamber  16 . Thus, the halogen heaters  30  and the transport conveyors  20  are isolated by the quartz glass plate  11 . By so doing, it is possible to prevent dust, or the like, produced because of driving of the transport conveyors  20  from entering the halogen heaters  30 . Note that in the above system, the decompression chamber  15  is desirably filled with inert gas, such as nitrogen, to suppress degradation of the halogen heaters  30 . 
     The transport conveyors  20  will be described with reference to  FIG. 2  and  FIG. 3 .  FIG. 2  is a plan view that shows the inside of the carrier transport system according to the present embodiment,  FIG. 3  is an enlarged view of the portion indicated at III of  FIG. 1  that shows the transport conveyor provided for the carrier transport system according to the present embodiment. As shown in  FIG. 2 , the transport conveyors  20  are provided respectively at both sides in a direction D 2  perpendicular to the transport direction D 1  in the heating chamber  16 . More specifically, the transport conveyors  20  are provided parallel to the transport direction D 1  over a range from a carrier entrance of the chamber  17  to a carrier exit of the chamber  17 , Each of the transport conveyors  20  includes transport rollers  21  and a drive motor  12  (see  FIG. 1 ). The transport rollers  21  are used to transport the carriers  40 . The drive motor  12  is used to drive the transport rollers  21 . 
     As shown in  FIG. 3 , the drive motor  12  transmits driving force to rotary shafts  23  via a belt  26  and drive pulleys  22 . Each rotary shaft  23  is rotatably supported by bearings provided respectively on a partition wall  24  and a support wall  27 . Then, each transport roller  21  is fixed to one end of a corresponding one of the rotary shafts  23 . From the above configuration, by driving the drive motor  12 , the transport rollers  21  may be rotated. 
     Each transport roller  21  is made of stainless steel (for example, SUS304L) of which the content of carbon is low in the material in consideration of hydrogen brittleness, or the like. As shown in  FIG. 2 , a line of the transport rollers  21  are provided at each end in the heating chamber  16  so as to be aligned in the transport direction D 1  of the carriers  40 . More specifically, as shown in  FIG. 3 , each transport roller  21  is arranged at a position distanced from the quartz glass plate  11 . In addition, each drive pulley  22  is arranged on the outer side of the transport roller  21  (on a side away from the quartz glass plate  11  and the halogen heater  30 ). This is because the belt  26  wound around each drive pulley  22  is made of resin and is poor heat-resistant. For this reason, the drive pulleys  22  and the belt  26  are desirably arranged on the outer side as much as possible. In addition, in terms of heating efficiency, the inside of the heating furnace  13  is desirably made compact as much as possible. 
     The positioning mechanism will be described with reference to  FIG. 4 .  FIG. 4  is a perspective view that shows the positioning mechanism provided for the carrier transport system according to the present embodiment. As shown in  FIG. 4 , the positioning mechanism includes carrier stoppers  35 , cylinders  37  (an example of the actuating means according to the aspect of the invention), and a control device (an example of the determination means according to the aspect of the invention). The carrier stoppers  35  are used to stop the carriers  40 . The cylinders  37  respectively move the carrier stoppers  35  toward the carriers  40 . The control device drives the carrier stoppers  35  and checks whether the carriers  40  are positioned. 
     Each of the carrier stoppers  35  has a comb shape and has a plurality of protrusions  35   a . As shown in  FIG. 2 , the carrier stoppers  35  are arranged respectively at both ends of the heating furnace  13  in the direction D 2  so as to extend in the transport direction D 1 . Although not shown in the drawing, two carrier stoppers  35  are provided at each end of the heating furnace  13 , that is, four carrier stoppers  35  are provided in total. The protrusions  35   a  are formed at equal intervals in the longitudinal direction of each carrier stopper  35 . The interval of the adjacent protrusions  35   a  is desirably sufficiently wider than the width of the carrier  40  in the transport direction D 1 . For example, in the present embodiment, the width of the carrier  40  in the transport direction is about 120 mm, whereas the interval of the adjacent protrusions  35   a  is designed to about 125 mm. As a result, when the carriers  40  are engaged with the carrier stoppers  35 , the carriers  40  are stopped at constant intervals (intervals of about 5 mm in the present embodiment) on the transport conveyors  20 . Each carrier stopper  35  is fixed to the distal ends of two stopper shafts  36  provided to extend in the direction D 2 . Each stopper shaft  36  is supported reciprocably in the direction D 2  by a shaft guide  38 . 
     Each cylinder  37  is provided between the two shaft guides  38 . Each cylinder  37  includes a piston rod  37   a  that is provided reciprocably in the direction D 2 . Then, the distal end of the piston rod  37   a  is coupled to the distal ends of the stopper shafts  36 , located on both sides, by a connecting member  39 . With the above configuration, as the cylinder  37  drives the piston rod  37   a  in the direction D 2 , the stopper shafts  36  coupled to the piston rod  37   a  via the connecting member  39  move the carrier stopper  35  in the direction D 2 . Each cylinder  37  according to the present embodiment is able to advance in two steps. This two-step advance action is implemented, for example, by providing two air chambers for an air cylinder or combining two cylinders in series with each other. Alternatively, by adjusting a moved distance using an electric cylinder, the above two-step advance action may be implemented. Note that each cylinder  37  according to the present embodiment is provided laterally with respect to the carrier stopper  35 ; instead, each cylinder  37  may be provided above the carrier stopper  35 . In addition, when the halogen heaters  30  are, for example, provided at the upper portion of the heating furnace  13 , each cylinder  37  should be provided below the carrier stopper  35  in terms of the influence of heat and installation space. 
     The carrier  40  will be described with reference to  FIG. 5 .  FIG. 5  is a plan view that shows the carrier provided for the carrier transport system according to the present embodiment. As shown in  FIG. 5 , the carrier  40  is a rectangular plate member made of aluminum. The carrier  40  includes two positioning pins  44  used for positioning a piece of work  50  and supported portions  40   a  supported by the transport rollers  21 . The positioning pins  44  are provided so as to protrude upward from predetermined positions of the upper surface of the carrier  40 . The supported portions  40   a  are provided at both end portions of the carrier  40  in the direction D 2 . As shown in  FIG. 1  and  FIG. 3 , each supported portion  40   a  is bent upward and laterally to form a stepped shape, and is mounted on the transport rollers  21 . Thus, as the drive motors  12  rotate the transport rollers  21 , the supported portions  40   a  (carrier  40 ) are transported in the transport direction D 1 . In addition, each supported portion  40   a  has a cutout groove  42  (an example of the engagement portion according to the aspect of the invention). 
     The cutout groove  42  is provided between protrusions  41  that are formed to protrude laterally at both ends of the supported portion  40   a  in the direction D 1 . The cutout groove  42  is formed to be wider than each protrusion  35   a  of the carrier stopper  35 . In addition, an insertion hole  42   a  is recessed in the direction D 2  at the rear end portion in the transport direction D 1  of one of the cutout grooves  42 . The distal end of each protrusion  35   a  of the carrier stopper  35  can be inserted into the insertion hole  42   a . Then, rear end surfaces  42   b  in the transport direction D 1  of the respective cutout grooves  42  are surfaces that are brought into contact with the protrusions  35   a  of the carrier stoppers  35 . 
     As shown in  FIG. 2 , the carrier transport system  10  according to the present embodiment includes temporary holding mechanisms  70  that temporarily hold the carrier  40  transported into the heating furnace  13 . The temporary holding mechanisms  70  are provided downstream of the positioning mechanism in the carrier transport direction D 1 . Each of the temporary holding mechanisms  70  includes a temporary stopper  60  and a temporary holding cylinder  61 . The temporary stopper  60  is brought into contact with the distal end portion in the transport direction of the first one carrier  40 . The temporary holding cylinder  61  drives the temporary stopper  60  in the direction D 2 . A drive shaft  65  of each temporary holding cylinder  61  extends through a shaft hole  64  that is formed in a guide case  63  in the direction D 2 . In addition, the distal end of the drive shaft  65  is fixed to the temporary stopper  60 . With the above configuration, as the temporary holding cylinder  61  drives the drive shaft  65  in the direction D 2 , the temporary stopper  60  is driven in the direction D 2 . 
     Next, the piece of work  50  transported by the carrier transport system  10  according to the present embodiment will be described with reference to  FIG. 5  to  FIG. 7B .  FIG. 6A  is a side cross-sectional view of a jig placed on a mount portion provided for the carrier transport system according to the present embodiment.  FIG. 6B  is a top view of the jig placed on the mount portion provided for the carrier transport system according to the present embodiment.  FIG. 7A  is a side cross-sectional view of a solder foil and element that are arranged on the mount portion provided for the carrier transport system according to the present embodiment.  FIG. 7B  is a top view of the solder foil and element that are arranged on the mount portion provided for the carrier transport system according to the present embodiment. The present embodiment refers to a case in which an inverter component is used as the piece of work  50 . As shown in  FIG. 5 , the inverter component  50  is mounted on the carrier  40  via a heat insulating material  43 . The inverter component  50  includes pin holes  50   b  and mount portions  50   a . The pin holes  50   b  are used for positioning. The mount portions  50   a  are used to arrange elements  51 . The pin holes  50   b  are provided at positions corresponding to the positioning pins  44  provided for the carrier  40 . In addition, a jig  56  for holding the element  51  is attached to each mount portion  50   a.    
     The jig  56  is made of carbon. As shown in  FIG. 6B , the jig  56  includes an arrangement hole  56   a  for arranging the element  51 , or the like, inside and an outer frame  56   b  for positioning the jig  56 . As shown in  FIG. 6A , an insulating substrate  54  is brazed onto the upper surface of the mount portion  50   a  using brazing filler metal  55 , and an aluminum pattern  53  is formed on the upper surface of the insulating substrate  54 . In addition, as shown in  FIG. 7A  and  FIG. 7B , the element  51  is arranged inside the arrangement hole  56   a  via a solder foil  52 . Note that a method of bonding the insulating substrate  54  is not limited to brazing; instead, another method of bonding, such as soldering, may be used. 
     Next, a control device  75  provided for the carrier transport system according to the present embodiment will be described with reference to  FIG. 8 .  FIG. 8  is a view that illustrates a first step of positioning the carriers according to the present embodiment. As shown in  FIG. 8 , the control device  75  includes a moved distance detection sensor  46  (an example of the moved distance detecting means according to the aspect of the invention) and proximity detection sensors  45 . The moved distance detection sensor  46  detects a moved distance of the carrier stopper  35  that is moved by the cylinder  37 . The proximity detection sensors  45  detect proximity of the carriers  40  in the transport direction D 1 . Then, on the basis of information acquired from these sensors  45  and  46 , the control device  75  drives the carrier stoppers  35  and the temporary stoppers  60 , and checks whether the carriers  40  have been positioned. Note that a laser irradiation device that uses a phototube, or the like, may be, for example, used as each sensor. 
     Next, how the inverter component  50  is treated in the heating furnace using the above configured carrier transport system  10  will be described in detail with reference to  FIG. 8  to  FIG. 13 .  FIG. 9  is a view that illustrates a second step of positioning the carriers according to the present embodiment.  FIG. 10  is a view that illustrates a third step of positioning the carriers according to the present embodiment.  FIG. 11  is a view that illustrates a fourth step of positioning the carriers according to the present embodiment.  FIG. 12  is a view that illustrates a fifth step of positioning the carriers according to the present embodiment.  FIG. 13  is a side view that shows a state where the carriers are positioned by the carrier stoppers according to the present embodiment. 
     In the carrier transport system  10 , the inverter components  50  are respectively mounted on the carriers  40  before the carriers  40  are transported into the heating furnace  13 . At this time, by inserting the positioning pins  44  of the carrier  40  into the pin holes  50   b  of the inverter component  50 , the inverter component  50  may be accurately positioned to the carrier  40 . Then, after the inverter components  50  are mounted respectively on the carriers  40 , the carriers  40  are transported by the transport conveyors  20  into the heating furnace  13 . Then, the carriers  40  transported into the heating furnace  13  are positioned by the positioning mechanism of the carrier transport system  10  in according with the following first to fifth steps. 
     In the first step, as shown in  FIG. 8 , the carrier transport system  10  drives the temporary holding cylinders  61  by the control device  75  to advance the temporary stoppers  60  toward the transport path of the carriers  40  beforehand. After that, the carrier transport system  10  drives the transport conveyors  20  to transport the carriers  40  into the heating furnace  13 . Then, the first one carrier  40  stops as the protrusions  41  thereof contacts the temporary stoppers  60 , and then the subsequent carriers  40  also contact the preceding carriers  40  to stop at predetermined positions. The control device  75  uses the proximity detection sensors  45  to detect that the carriers  40  have reached the predetermined positions. Then, the carrier transport system  10  uses the control device  75  to check the proximity of the carriers  40 , and then stops the transport conveyors  20 . 
     With the carrier transport system  10 , the proximity of the carriers  40  transported by the transport conveyors  20  is detected by the proximity detection sensors  45 , and it is possible to accurately determine that the carriers  40  are transported to the predetermined positions on the basis of the detected information. Thus, in the next second step, the carrier stoppers  35  may be advanced toward the carriers  40  at an adequate timing. As a result, it is possible to prevent interference between the carrier stoppers  35  and the carriers  40  and further accurately position the carriers  40 . Note that it is also applicable that a deceleration sensor is provided upstream of the proximity detection sensors  45  in the transport direction D 1  and then a transport speed at which the carriers  40  are transported by the transport conveyors  20  is reduced when the deceleration sensor detects the proximity of the carriers  40 . By so doing, it is possible to temporarily stop the carriers  40  by the temporary stoppers  60  further reliably. 
     In the second step, as shown in  FIG. 9 , the carrier transport system  10  uses the control device  75  to drive the cylinders  37  to advance the carrier stoppers  35 , located on both sides, toward the carriers  40 . At this time, in the carrier transport system  10 , the cutout grooves  42  of the carriers  40  are wider in the transport direction D 1  of the carriers  40  than the protrusions  35   a  of the carrier stoppers  35 . Thus, the protrusions  35   a  may be easily inserted into the cutout grooves  42  by advancing the carrier stoppers  35  toward the carriers  40 . 
     Each of the protrusions  35   a  of the carrier stoppers  35  is inserted into a middle portion in the transport direction (front portion in the transport direction in the case of the first one carrier  40 ) of the corresponding cutout groove  42  of the carrier  40 . In this way, by inserting the protrusions  35   a  of the carrier stoppers  35  into the middle portions in the transport direction of the cutout grooves  42  of the carriers  40 , the protrusions  35   a  may be reliably inserted into the cutout grooves  42  of the carriers  40 . In addition, the control device  75  drives the temporary holding cylinders  61  in synchronization with the cylinders  37 , and recedes the temporary stoppers  60  to the sides opposite to the transport path of the carriers  40 . 
     In the third step, as shown in  FIG. 10 , the carrier transport system  10  uses the transport conveyors  20  to further move the carriers  40  in the transport direction D 1 . Then, the carriers  40  sequentially stop from the ones at the upstream side in the transport direction D 1  in such a manner that the rear end surfaces  42   b  in the transport direction of the cutout grooves  42  are brought into contact with the protrusions  35   a  of the carrier stoppers  35 . As a result, the carriers  40  are positioned at predetermined intervals in the transport direction D 1  at a time. Here, in the present embodiment, the carriers  40  are positioned so that the carriers  40  respectively face the halogen heaters  30 . Therefore, the inverter components  50  mounted respectively on the carriers  40  may be adequately heated by the halogen heaters  30  without waste. Moreover, the carriers  40  are positioned from both sides with respect to the transport direction D 1 . Thus, it is possible to further accurately position the carriers  40 . 
     In the fourth step, as shown in  FIG. 11 , after all the carriers  40  have been positioned, the carrier transport system  10  uses the control device  75  to drive the cylinders  37  to advance one of the carrier stoppers  35  further toward the carriers  40 . By so doing, the distal ends of the protrusions  35   a  of the one of the carrier stoppers  35  are inserted into the insertion holes  42   a  provided in the cutout grooves  42  of the carriers  40 . Note that at this time, the carrier stoppers  35  may be advanced to positions at which the carrier stoppers  35  hold the carriers  40 . In this way, by holding the carriers  40  with the carrier stoppers  35 , the carriers  40  may be positioned in the direction D 2 . Thus, the inverter components  50  mounted respectively on the carriers  40  may be further accurately arranged so that the inverter component  50  respectively face the halogen heaters  30  in the heating furnace  13 . As a result, the inverter components  50  may be further adequately heated without waste. 
     In the fifth step, as shown in  FIG. 12 , after the distal ends of the protrusions  35   a  have been inserted into the insertion holes  42   a , the control device  75  of the carrier transport system  10  determines, on the basis of a moved distance X of the carrier stopper  35  detected by the moved distance detection sensor  46 , whether the carriers  40  are properly positioned. At this time, a total moved distance of a moved distance in the second step and a moved distance in the fourth step is used as the moved distance X of the carrier stopper  35 . Instead, only a moved distance in the fourth step may be used as the moved distance X of the carrier stopper  35 . Then, the control device  75  determines that the carriers  40  are properly positioned when the moved distance X of the carrier stopper  35  exceeds a predetermined reference value. On the other hand, the control device  75  determines that the carriers  40  are not properly positioned when the moved distance of the carrier stopper  35  is smaller than or equal to the predetermined reference value. The reference value may be a moved distance of the carrier stopper  35  at the time when the distal ends of the protrusions  35   a  start to be inserted into the insertion holes  42   a.    
     With the carrier transport system  10 , the distal end of the protrusion  35   a  of the carrier stopper  35  cannot be inserted into the insertion hole  42   a  of the carrier  40  that is not properly positioned. Therefore, the carrier stopper  35  can be advanced toward the carriers  40  only when all the carriers  40  are positioned accurately. Thus, even when only one of the carriers  40  is inaccurately positioned, the moved distance X of the carrier stopper  35  is smaller than or equal to the reference value. Hence, it is possible to detect that the carriers  40  are not positioned accurately. Note that the carrier transport system  10  positions the carriers again when the carrier transport system  10  detects that the carriers  40  are not positioned accurately. By so doing, the carrier transport system  10  is able to further accurately position the carriers  40 . 
     After the carrier transport system  10  detects that all the carriers  40  are accurately positioned, the carrier transport system  10  stops the transport conveyors  20 . Then, as shown in  FIG. 13 , the carrier transport system  10  starts heating the inverter components  50  by the halogen heaters  30 . As the inverter components  50  are heated by the halogen heaters  30 , the solder foil  52  provided on each inverter component  50  melts. After that, the carrier transport system  10  releases positioning of the carriers  40  and drives the transport conveyors  20  to transport the carriers  40  out from the exit of the heating furnace  13 . In each of the inverter components  50  transported to the outside of the heating furnace  13 , the solder foil  52  is cooled and solidified, and the element  51  is soldered to the inverter component  50 . 
     Here, in the present embodiment, the carriers  40  are made of aluminum. Then, when the inverter components  50  are heated by the halogen heaters  30 , the carriers  40  are also heated to about a little below 400° C. Because of the above heating, the carriers  40  made of aluminum expand by about several millimeters. Thus, when the plurality of carriers  40  are arranged adjacent to each other in the heating furnace  13 , the carriers  40  are influenced by the expansion from each other and are deviated in position. As a result, there is a possibility that the inverter components  50  may not be exposed equally to infrared rays irradiated from the halogen heaters  30 . In contrast, in the carrier transport system  10 , the carriers  40  are positioned at the predetermined intervals in the transport direction D 1  at a time so that the carriers  40  respectively face the halogen heaters  30 . By so doing, the carrier transport system  10  prevents the influence due to the expansion of each carrier  40  on the other carriers  40  to make it possible to suppress a positional deviation of each carrier  40  due to the expansion. As a result, it is possible to equally heat the inverter components  50  by the halogen heaters  30 . 
     Note that in the present embodiment, the third step is performed after the second step has been completed; instead, the second step and the third step may be performed in parallel with each other. In addition, in the present embodiment, advance of the carriers  40  is once stopped after the second step has been completed and then the carriers  40  are advanced again in the fourth step; instead, the second step and the fourth step may be continuously performed. 
     As described in detail above, with the carrier transport system  10  according to the present embodiment, by determining whether the carriers  40  are properly positioned, even when the carriers  40  are not positioned accurately because, for example, the carriers  40  get caught on something, it is possible to detect the inaccurate positioning and then position the carriers  40  again. By so doing, it is possible to, for example, appropriately process or treat the inverter components  50  mounted respectively on the carriers  40 . In addition, the plurality of carriers  40  may be positioned at a time and then the positioning may be checked, so working efficiency is favorable. 
     Furthermore, the carrier transport system  10  detects the moved distance X of the carrier stopper  35  to check whether the carriers  40  are positioned accurately. Thus, it is not necessary to provide a plurality of position detecting means (position sensors, or the like) in correspondence with the carriers  40 . Therefore, it is not necessary to ensure a large space in the side surface of the chamber  17  of the heating furnace  13  to form a plurality of quartz windows. As a result, it is possible to position the plurality of carriers  40  in the heating furnace  13  at a time and to check whether all the carriers  40  are positioned accurately with a simple configuration. 
     Next, a carrier transport system according to a second embodiment of the invention will be described with reference to  FIG. 14 .  FIG. 14  is a schematic configuration diagram that shows the carrier transport system according to the second embodiment. Note that in the carrier transport system according to the second embodiment, like reference numerals in the drawing denote like components to those of the first embodiment, and the description thereof is omitted where appropriate, and then the difference will be mainly described below. The carrier transport system according to the second embodiment differs from the first embodiment in the shape of one of carrier stoppers. That is, as shown in  FIG. 14 , a carrier stopper  85  has rotation preventing portions  86 , which contact parts of the carriers  40  to prevent rotation of the carriers  40 . The rotation preventing portions  86  are formed to extend from both ends of the carrier stopper  85  in the longitudinal direction. 
     In the carrier transport system, when the carriers  40  rotate, parts of the carriers  40  contact the rotation preventing portions  86  of the carrier stopper  85 . Thus, rotation of the carriers  40  may be suppressed. In this manner, it is possible to further accurately position the carriers  40 , so the inverter components  50  may be further accurately arranged so that the inverter components  50  respectively face the halogen heaters  30 . As a result, the inverter components  50  may be further adequately heated without waste. Note that in  FIG. 14 , the rotation preventing portions  86  are provided only for the one carrier stopper  85 ; instead, the rotation preventing portions  86  may be provided for the carrier stoppers located on both sides. By so doing, the carriers  40  may be further accurately positioned. 
     Next, a carrier transport system according to a third embodiment of the invention will be described with reference to  FIG. 15 .  FIG. 15  is a schematic configuration diagram that shows the carrier transport system according to the third embodiment. Note that in the carrier transport system according to the third embodiment, like reference numerals in the drawing denote like components to those of the above embodiments, and the description thereof is omitted where appropriate, and then the difference will be mainly described below. The carrier transport system according to the third embodiment differs from the above embodiments in the shape of protrusions provided for one of carrier stoppers. That is, as shown in  FIG. 15 , protrusions  96  of a carrier stopper  95  located on one side according to the present embodiment each have an insertion portion  96   a  and a contact portion  96   b . The insertion portion  96   a  is inserted into the insertion hole  42   a . The contact portion  96   b  contacts a bottom surface of the cutout groove  42 . 
     In this carrier transport system, the insertion portions  96   a  and contact portions  96   b  of the protrusions  96  of the one carrier stopper  95  and the protrusions  35   a  of the other carrier stopper  85  are used to be able to hold the carriers  40 . In this way, by holding the carriers  40 , it is possible to effectively suppress a positional deviation of each carrier  40  in the direction D 2  and rotation of each carrier  40 . 
     Note that the above embodiments are just illustrative and are not intended to limit the invention, and the above embodiments may be, of course, variously modified or improved without departing from the scope of the invention. For example, in the above embodiments, the carrier stopper  35 ,  85  or  95  approaches the carriers  40  laterally with respect to the transport conveyor  20 ; instead, the carrier stopper  35 ,  85  or  95  may approach the carriers  40  from the upper side with respect to the transport conveyor  20 . In addition, the shape of the cutout groove  42  of each carrier  40  or the shape of the protrusion  35   a  or  96  of each carrier stopper  35 ,  85  or  95  may be freely changed depending on a mode for positioning, or the like. Furthermore, the carrier transport system according to the above embodiments may be used to position the carriers  40  outside the heating furnace  13 . 
     While the invention has been described with reference to example embodiments thereof, it should be understood that the invention is not limited to the example embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the example embodiments are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.