Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/267,972 (now U.S. Pat. No. 7,726,886), filed Nov. 10, 2008, and is a divisional of U.S. application Ser. No. 11/757,711 (now U.S. Pat. No. 7,467,899), filed Jun. 4, 2007, the entire contents of which are incorporated herein by reference. 
     U.S. application Ser. No. 11/757,711 claims priority to Japanese application No. 2007-021298, filed Jan. 31, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a ferrule transfer method of transferring a ferrule with a built-in optical fiber that is fusion-spliced with an optical fiber to a fusion-spliced-portion reinforcing device and a ferrule holder for holding the ferrule. 
     2. Description of the Related Art 
     Recently, with the prevalence of FTTH (Fiber To The Home) and the like, an optical communication network is widely used at general households. Along with this condition, various splicing methods of assembling an optical connector without performing a polishing step and splicing optical fibers are employed at a splicing site. 
     As the optical connector, there is known a mechanical optical connector in which one end of a built-in optical fiber matches a splicing end of the ferrule and the other end of the built-in optical fiber is protruded from the other end of the ferrule where a mechanical holding unit is provided (see, for example, Japanese Patent Application Laid-open No. H10-206688, Japanese Patent Application Laid-open No. H11-142686, Japanese Patent Application Laid-open No. H11-142687, Japanese Patent Application Laid-open No. H11-160563, and Japanese Patent Application Laid-open No. 2000-347068). In the mechanical optical connector, the other end of the built-in optical fiber and one end of another optical fiber are mechanically held to splice them in such a manner that their axis centers match each other so that an optical connector can be provided on the one end of another optical fiber. 
     In these days, an optical connector is provided in which a built-in optical fiber and another optical fiber are fusion-spliced to enhance a long-time reliability (see, for example, Japanese Patent Application Laid-open No. 2002-82257). 
       FIG. 19  is a schematic partial section view of a conventional optical connector  10  disclosed in Japanese Patent Application Laid-open No. 2002-82257. The optical connector  10  includes a ferrule  11 , a built-in optical fiber  12 , a housing  15 , and a coil spring  20 , and is fusion-spliced with an optical fiber core  14 , with a fusion-spliced portion reinforced with a reinforcing body  13 . 
     The housing  15  includes a plug housing  16 , a stopper ring  17 , and a boot  18 . The plug housing  16  and the stopper ring  17  are coupled by engaging an engagement hole  16   a  and an engagement protrusion  17   a . The boot  18  is attached to the stopper ring  17  that constitutes a rear portion of the housing  15 . The boot  18  includes an attaching portion  18   a  and a bending portion  18   b . The coil spring  20  is placed between the ferrule  11  and the stopper ring  17 , holding the ferrule  11  in a movable manner in an axis direction. 
     The built-in optical fiber  12  is formed by cutting in advance an appropriate optical fiber by a predetermined length at a manufacturing factory, and inserting and fixing it in the ferrule  11 . One end of the built-in optical fiber  12  and a splicing end of the ferrule  11  are polishing-processed in advance, and are processed not to cause splicing loss with another optical connector spliced. On the other hand, removal of a coating and end processing for fusion splicing are required for the other end of the built-in optical fiber  12  that protrudes backward of the ferrule  11 , which are generally performed in advance at a manufacturing factory and the like. 
     Removal of a coating and end processing with regard to the optical fiber core  14  to be spliced to the optical connector  10  are performed at the splicing site. Machine tools for the processing are provided at the splicing site. 
       FIGS. 20 to 22  depict an operation of fusion splicing between the built-in optical fiber attached by insertion into the ferrule  11  and the optical fiber core  14 . The operation of fusion splicing is performed at the splicing site. Prior to the fusion splicing, as shown in  FIG. 20 , at the end of the built-in optical fiber  12  that is to be fusion-spliced, a coating  12   a  is removed so that a bare optical fiber portion  12   b  is exposed in advance at a factory as described above. In addition, at an end of the optical fiber core  14 , a coating  14   a  is removed so that a bare optical fiber portion  14   b  is exposed. Then, the bare optical fiber portions  12   b  and  14   b  are placed at a fusion-splicing device by a holder that holds them, their centers are aligned on a V-shaped groove of the holder, and the bare optical fiber portions  12   b  and  14   b  are clamped. Then, as shown in  FIG. 21 , an electric discharge is applied to them through an arc discharge A from discharge electrodes  22   a  to heat them for fusion splicing, thereby forming a fusion-spliced portion  19 . Mechanical strength of the fusion-spliced portion  19  is degraded because of removed coating so that the fusion-spliced portion  19  is transferred to a later-described fusion-spliced-portion reinforcing device. Then, as shown in  FIG. 22 , the fusion-spliced portion  19  is covered by the reinforcing body  13 . 
     The reinforcing body  13  is a heat-shrinkable tube that includes a reinforcing member such as metal and thermoplastic resin. The fusion-spliced portion  19  is covered by the reinforcing body  13  and is transferred to the fusion-spliced-portion reinforcing device. The reinforcing body  13  is heated and contracted so that it covers the fusion-spliced portion  19 . Besides using the reinforcing body  13  as a means of protecting the fusion-spliced portion, a recoating method of coating the fusion-spliced portion with a UV-curing resin and hardening the UV-curing resin to form a coating layer is also used. 
       FIG. 23  is a view of an example of a main unit of a conventional fusion-splicing device  21  that fusion-splices optical fibers. It is indicated that a fusion-splicing operation unit  22  is arranged at the center and a fusion-spliced-portion reinforcing device  23  is arranged above the fusion-splicing operation unit  22 . Optical fiber holders H that causes optical fibers F to face each other on their ends to arrange and fix them are arranged both sides of the fusion-splicing operation unit  22 , and the discharge electrodes  22   a  to cause the arc discharge are arranged at its center. The fusion-spliced-portion reinforcing device  23  includes a long heating chamber  23   a  that extends laterally in a straight line and holders  23   b  that are arranged at both ends of the heating chamber  23   a  and that give tension to fusion-spliced optical fibers and hold optical fibers F. A reference sign  22   b  is a lid that covers the fusion-splicing operation unit  22  and a reference sign  23   c  is a lid that covers the fusion-spliced-portion reinforcing device  23 . 
     When the built-in optical fiber  12  fitted into the ferrule  11  and the optical fiber core  14  are fusion-spliced by the fusion-splicing device  21 , one of optical fiber holders is replaced with a ferrule holder. 
     To attach a reinforcing body to the fusion-spliced portion of the ferrule in which the optical fiber and the built-in optical fiber are fusion-spliced and to give a mechanical protection as described above, it is necessary to transfer the ferrule from the fusion-splicing operation unit of the fusion-splicing device to the fusion-spliced-portion reinforcing device. However, because an optical fiber is not attached at the splicing end of the ferrule, it is impossible to hold and transfer each of optical fibers as in a case of a conventional fusion-splicing of optical fibers. For this reason, as shown in  FIG. 24 , it is considered that the ferrule  11  and the optical fiber core  14  are pinched by a pinching device  25  that includes pinching units  25   a ,  25   a  having a shape like a clothespin and are transferred from the fusion-splicing operation unit  22  to the heating chamber  23   a  of the fusion-spliced-portion reinforcing device  23 . The pinching device  25  in which the pinching units  25   a ,  25   a  are coupled by a rod-shaped coupling member  25   b  having a predetermined length to maintain a predetermined distance therebetween is arranged and is constituted not to give a tension to the fusion-spliced portion when transferring the ferrule and the optical fiber. 
     However, to accommodate the fusion-spliced portion  19  and the reinforcing body  13  in the heating chamber  23   a  using the method of pinching the ferrule  11  and the like by the pinching device  25  and transferring them, because the heating chamber  23   a  has a narrow insertion slot, the pinching device  25  should be reduced in size to be accommodated in the heating chamber  23   a  while the pinching device  25  pinches the ferrule  11  and the like, or the reinforcing body  13  and the ferrule  11  have to be fallen in the heating chamber  23   a  by stopping pinching the ferrule  11  above the heating chamber  23   a . However, when accommodating the ferrule  11  by use of the small pinching device  25  in the heating chamber  23   a , it is impossible to close the lid  23   c  of the fusion-spliced-portion reinforcing device  23 . This makes it impossible to stably contract the reinforcing body  13  like a heat-shrinkable tube. Alternatively, a method can be considered that an equivalent for a lid is arranged around the pinching device  25  and the equivalent covers the heating chamber  23   a . However, the method causes problems of a poor workability, a higher price because of a higher component count, and the like. Furthermore, the method of falling the reinforcing body  13  and the ferrule  11  from above the fusion-spliced-portion reinforcing device  23  has problems of a possibility of cutting the fusion-spliced portion  19  due to an impulse of falling, being unable to contract the heat-shrinkable tube in a good shape because fusion-spliced optical fibers cannot be straightly held, and the like. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     A ferrule transfer method according to one aspect of the present invention is for placing a ferrule in which one end of a built-in optical fiber matches a splicing end surface and other end of the built-in optical fiber is protruded from an end portion opposite to the splicing end surface and one end of a splicing optical fiber to be spliced to the built-in optical fiber at a fusion-splicing operation unit of a fusion-splicing device, fusion splicing the other end of the built-in optical fiber with the one end of the splicing optical fiber, and then transferring the ferrule to a fusion-spliced-portion reinforcing device. The ferrule transfer method includes holding the ferrule by inserting a cylindrical portion of the ferrule into a holding unit of a ferrule holder from the splicing end surface; and transferring the ferrule while holding a stem extended on an opposite side of the holding unit of the ferrule holder and the splicing optical fiber. 
     A ferrule holder according to another aspect of the present invention includes a holding unit into which a cylindrical portion of a ferrule is inserted from a splicing end surface of the ferrule and by which the ferrule is held; and a stem that is extended on an opposite side of the holding unit. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic exploded view of a ferrule holder according to a first embodiment of the present invention. 
         FIG. 2  is a schematic front view of the ferrule holder according to the first embodiment of the present invention. 
         FIG. 3  is a schematic partial section side view of the ferrule holder according to the first embodiment of the present invention. 
         FIG. 4  is a schematic diagram illustrating a step of fusion splicing between a ferrule and a splicing optical fiber. 
         FIG. 5  is a schematic diagram illustrating a step of fusion splicing between the ferrule and the splicing optical fiber. 
         FIG. 6  is a schematic diagram illustrating a step of fusion splicing between the ferrule and the splicing optical fiber. 
         FIG. 7  is a schematic diagram illustrating a step of fusion splicing between the ferrule and the splicing optical fiber. 
         FIG. 8  is a schematic diagram illustrating how a ferrule is transferred according to a second embodiment of the present invention. 
         FIG. 9  is a schematic perspective view of a ferrule holder as an example in which the ferrule and the ferrule holder are placed. 
         FIG. 10  is a schematic view of a transfer arm used in a third embodiment of the present invention. 
         FIG. 11  is a schematic diagram illustrating a method of transferring the ferrule by use of the transfer arm shown in  FIG. 10 . 
         FIG. 12  is a schematic diagram illustrating a method of transferring the ferrule by use of the transfer arm shown in  FIG. 10 . 
         FIG. 13  is a schematic diagram illustrating a method of transferring the ferrule by use of the transfer arm shown in  FIG. 10 . 
         FIG. 14  is a perspective view for explaining how the transfer arm used in the third embodiment is mounted on a fusion-splicing device. 
         FIG. 15  is a schematic perspective view of a ferrule holder according to another embodiment of the present invention. 
         FIG. 16  is a schematic perspective view of a ferrule holder according to still another embodiment of the present invention. 
         FIG. 17  is a schematic perspective view of a ferrule holder according to still another embodiment of the present invention. 
         FIG. 18  is a schematic perspective view of a ferrule holder according to still another embodiment of the present invention. 
         FIG. 19  is a schematic partial section view of a conventional optical connector. 
         FIG. 20  is a schematic diagram illustrating an operation of fusion splicing between a built-in optical fiber fitted by insertion into a ferrule and an optical fiber. 
         FIG. 21  is a schematic diagram illustrating the operation of fusion splicing between the built-in optical fiber fitted by insertion into the ferrule and the optical fiber. 
         FIG. 22  is a schematic diagram illustrating the operation of fusion splicing between the built-in optical fiber fitted by insertion into the ferrule and the optical fiber. 
         FIG. 23  is a view of an example of a main unit of a conventional fusion-splicing device that fusion-splices optical fibers. 
         FIG. 24  is a view of an example of a pinching device that transfers the ferrule. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Exemplary embodiments of a ferrule transfer method and a ferrule holder according to the present invention are explained in detail below with reference to  FIGS. 1 to 18 . The present invention is not limited to the embodiments and it is possible to modify the embodiments in various manners within a scope not departing from the gist of the present invention. 
     (First Embodiment) 
     An explanation is first given about a ferrule holder according to a first embodiment of the present invention.  FIGS. 1 to 3  are schematic diagrams of the ferrule holder according to the first embodiment.  FIG. 1  is an exploded view,  FIG. 2  is a front view, and  FIG. 3  is a partial section side view of the ferrule holder. As shown in  FIGS. 1 to 3 , a ferrule holder  30  includes a holder body  31 , a holding unit  32 , a stem  33 , and a tube-shaped fixing member  34 . 
     The holder body  31  includes a central portion  31   c  that has substantially the same outer diameter as that of a cylindrical portion of a ferrule to be held, and a tip  31   a  and a rear end  31   b  having a diameter smaller than that of the central portion  31   c . An outer diameter of the tip  31   a  is formed slightly smaller than that of the cylindrical portion of the ferrule to be held. 
     The holding unit  32  that is made of an elastic material is cylindrically formed to have a slit  32   a  in a longitudinal direction and an inner diameter slightly smaller than the outer diameter of the cylindrical portion of the ferrule to be held. The stem  33  is constituted of a string that has much flexibility or a rod that has no flexibility. The fixing member  34  is formed to have an inner diameter slightly smaller than an outer diameter of the central portion  31   c  of the holder body  31 . 
     The ferrule holder  30  can be assembled by inserting the stem  33  into a hole formed in the rear end  31   b  of the holder body  31 , fixing the stem  33  by a method of caulking the rear end  31   b  or applying an adhesive into the hole, fitting one end of the holding unit  32  over the tip  31   a  of the holder body  31 , and fixing the holding unit  32  and the holder body  31  in an integrated manner by covering the fixing member  34  on at least the fitted portion. 
     When the cylindrical portion of the ferrule to be held is inserted into a tip  32   b  of the holding unit  32 , an inner diameter of the holding unit  32  made of an elastic material in which the slit  32   a  is formed is slightly enlarged to generate a repulsive force, thereby enabling the ferrule holder  30  to mechanically hold the ferrule. The stem  33  is extended on the opposite side of the holding unit  32  in the ferrule holder  30  and is constituted to easily hold the ferrule holder  30 . 
     As an example of each of the above components, the holder body  31  is made of a soft material such as Teflon®. The tip  31   a  is 2.4 millimeters in outer diameter, the central portion  31   c  is 3 millimeters in outer diameter, and the rear end  31   b  is 2 millimeters in outer diameter. The holding unit  32  is made of a spring or the like with 11 millimeters in length, 2.4 millimeters in inner diameter, and 3 millimeters in outer diameter. The stem  33  is made of a material, such as wire, piano wire, an optical fiber, with outer diameter in the order of 0.9 millimeters and length in the order of 20 centimeters. The fixing member  34  is formed of a heat shrinkable tube with inner diameter in the order of 3 millimeters and outer diameter in the order of 4 millimeters. As the holding unit  32 , a separating sleeve used for a connection adaptor of an optical connector can be used. 
     Each component is arranged in a heating chamber of a fusion-spliced-portion reinforcing device when reinforcing the fusion-spliced portion. Thus, in a device in which a heat shrinkable tube is heated in the fusion-spliced-portion reinforcing device, each component is required to be made of a material capable of resisting a temperature of 230° C. that is a heating temperature in the fusion-spliced-portion reinforcing device  23 . 
     By use of the ferrule holder  30  according to the first embodiment, it is possible to easily transfer the ferrule fusion-spliced with an optical fiber to the fusion-spliced-portion reinforcing device and reinforce the fusion-spliced portion in a good condition. An explanation is given below about a ferrule transfer method by use of the ferrule holder according to the first embodiment, as a second embodiment of the present invention. 
     (Second Embodiment) 
       FIGS. 4 to 7  are schematic diagrams illustrating a step of a fusion-splicing between a ferrule and a splicing optical fiber, which is a step before a ferrule transfer method according to the second embodiment. As shown in  FIG. 4 , the ferrule holder  30  according to the first embodiment, a ferrule  40  with a built-in optical fiber, and a splicing optical fiber  45  are prepared. The ferrule  40  is arranged in such a manner that one end  43   a  of a built-in optical fiber  43  matches a splicing end  41   a  of its cylindrical portion  41  and a bare optical fiber portion  43   b  that is the other end of the built-in optical fiber  43  is protruded from a ferrule end  41   b  on the opposite side of the splicing end  41   a . The ferrule  40  includes a guard  42  to fix the ferrule  40  to a housing of an optical connector. The ferrule  40  is similar to a conventional ferrule  11  shown in  FIG. 19 . The splicing optical fiber  45  is an optical fiber to be spliced to the built-in optical fiber  43 , a coating  45   a  is removed on one end of the splicing optical fiber  45 , and a bare optical fiber portion  45   b  is exposed in the same way as a conventional optical fiber core  14  shown in  FIG. 20 . 
     As shown in  FIG. 5 , the cylindrical portion  41  of the ferrule  40  is inserted into the tip  32   b  of the holding unit  32  of the ferrule holder  30 , and the inner diameter of the holding unit  32  is being enlarged and the holding unit  32  is fitted over the cylindrical portion  41  of the ferrule  40 . As a result, the holding unit  32  mechanically holds the ferrule  40  by a repulsive force generated by its enlarged inner diameter. The holder body  31  is made of a soft material such as Teflon®, so that even if the end  43   a  of the built-in optical fiber  43  butts the holder body  31  in an inserting operation, it is possible to prevent the end  43   a  from being damaged. 
     The ferrule  40  that is mechanically held by the holding unit  32  and the splicing optical fiber  45  are arranged in the fusion-splicing operation unit  22  of the conventional fusion-splicing device  21  shown in  FIG. 23  in such a manner that an end of the bare optical fiber portion  43   b  of the built-in optical fiber  43  in the ferrule  40  and an end of the bare optical fiber portion  45   b  of the splicing optical fiber  45  face each other. The splicing optical fiber  45  is previously inserted into a heat-shrinkable reinforcing body  48 . As shown in  FIG. 6 , the end of the bare optical fiber portion  43   b  and the end of the bare optical fiber portion  45   b  are fusion-spliced through an arc discharge A generated from the discharging electrodes  22   a  of the fusion-splicing device  21 . 
     As shown in  FIG. 7 , the reinforcing body  48  is moved to include and involve the bare optical fiber portions  43   b ,  45   b  and a fusion-spliced portion  49 , and the ferrule  40  together with the splicing optical fiber  45  are transferred to the fusion-spliced-portion reinforcing device  23 . 
     As shown in  FIG. 8 , in the ferrule transfer method according to the second embodiment, the splicing optical fiber  45  and the stem  33  of the ferrule holder  30  that holds the ferrule  40  are held to transfer the ferrule  40 . As a result, compared with a conventional method, it is possible to easily transfer the ferrule  40  and stably house it in the heating chamber  23   a  of the fusion-spliced-portion reinforcing device  23 . 
     Then, the reinforcing body  48  is heated in the heating chamber  23   a  of the fusion-spliced-portion reinforcing device  23  and is subject to heat shrinkage. The fusion-spliced portion  49  and the bare optical fiber portions  43   b ,  45   b  are covered by the reinforcing body  48  in a good condition. As a result, the fusion-spliced portion  49  is reinforced well and becomes more reliable. 
     According to the second embodiment, when performing a fusion-splicing by use of the fusion-splicing device  21  shown in  FIG. 23 , the fusion splicing is performed by replacing one of optical fiber holders H with a ferrule holder  50 .  FIG. 9  is a schematic perspective view of an example of the ferrule holder  50  while the ferrule and the ferrule holder are placed thereon. 
     The ferrule holder  50  includes a holder base  51  that has a bottom shape and a dimension that are long and wide enough to be set in the fusion-splicing device  21  instead of the optical fiber holder H. A groove  52  in which the ferrule holder  30  and the ferrule  40  held by the ferrule holder  30  can be arranged and fixed is formed on an upper surface of the holder base  51 . A metal lid  53  that is rotatably fixed through a hinge mechanism  53   a  is arranged on a side of the holder base  51  and covers the ferrule  40  and the ferrule holder  30  that are placed on the groove  52 . The metal lid  53  can be fixed by use of a magnetic force of a magnet  54  arranged in the holder base. As shown in  FIG. 9 , the ferrule  40  is placed in the ferrule holder  50 , which is set at a holder arranging position in the fusion-splicing operation unit  22  of the fusion-splicing device  21 . This makes it possible to reliably arrange the ferrule  40  in the fusion-splicing operation unit  22  of the fusion-splicing device  21 . 
     The ferrule holder  30  includes, as described above, the stem  33  at one end and the holding unit  32  at the other end that holds the cylindrical portion  41  of the ferrule  40 . Therefore, when the built-in optical fiber  43  and the splicing optical fiber  45  are fusion-spliced, it is different from a conventional operation of fusion-splicing optical fibers in a fact that the ferrule  40  is placed in the ferrule holder  50  of the fusion-splicing device  21 . However, by employing the stem  33  as one of optical fibers when fusion-splicing optical fibers, a conventional technology of transferring the fusion-spliced portion when fusion-splicing optical fibers can be applied as it is. 
     (Third Embodiment) 
     A specific explanation is given below about a ferrule transfer method according to a third embodiment of the present invention. The ferrule transfer method according to the third embodiment is different from the ferrule transfer method according to the second embodiment in a fact that a splicing optical fiber that is fusion-spliced with the ferrule and the stem of the ferrule holder that holds the ferrule are held by use of a transfer arm to transfer the ferrule. 
       FIG. 10  is a schematic view of a transfer arm  60  used in the third embodiment. As shown in  FIG. 10 , the transfer arm  60  includes a fixing arm  61 , rotation shaft supporting units  62 ,  62  arranged at both ends of the fixing arm  61 , a movable arm  63  that can be rotated about the rotation shaft supporting units  62 ,  62 , and pinching units  64 ,  64  which are arranged respectively at both ends of the movable arm  63 . As shown in  FIG. 14 , the transfer arm  60  is mounted on top of the fusion-splicing device  21  by fixing the fixing arm  61  on a back surface of the fusion-spliced-portion reinforcing device  23 . 
     An explanation is given below about the ferrule transfer method by use of the transfer arm  60  with reference to  FIGS. 10 to 13 . As shown in  FIG. 10 , the movable arm  63  is first rotated and is moved to the same side of the fixing arm  61  as if they are folded. Similarly to the case of the second embodiment, the ferrule  40  that is held by the ferrule holder  30  and the splicing optical fiber  45  are arranged in the fusion-splicing operation unit  22  of the fusion-splicing device  21  so that the end of the bare optical fiber portion  43   b  of the built-in optical fiber  43  in the ferrule  40  and the end of the bare optical fiber portion  45   b  of the splicing optical fiber  45  face each other. Then, the built-in optical fiber  43  and the splicing optical fiber  45  are fusion-spliced and bare optical fiber portions that include the fusion-spliced portion are covered by the reinforcing body  48 . 
     As shown in  FIG. 11 , the movable arm  63  is moved by a rotation to the side of the fusion-splicing operation unit  22  of the fusion-splicing device  21 . One pinching unit  64  pinches the splicing optical fiber  45  and the other pinching unit  64  pinches the stem  33  of the ferrule holder  30 . 
     The movable arm  63  is half-rotated to pass through a condition shown in  FIG. 12  to the side of the fixing arm  61  shown in  FIG. 13 . As a result, the ferrule  40  is transferred with the splicing optical fiber  45 . While the movable arm  63  is half-rotated, the reinforcing body  48  is housed in the heating chamber  23   a  of the fusion-spliced-portion reinforcing device  23 . 
     Holders  23   b  of the fusion-spliced-portion reinforcing device  23  hold the splicing optical fiber  45  and the stem  33  of the ferrule holder  30 . Tension is exerted to the fusion-spliced portion  49  to operate the fusion-spliced-portion reinforcing device  23  and the fusion-spliced portion  49  is covered by the reinforcing body  48 . 
     According to the third embodiment, the ferrule  40  is transferred by use of the transfer arm  60  so that the ferrule  40  can be easily transferred and the reinforcing body  48  can be reliably housed in the heating chamber  23   a  of the fusion-spliced-portion reinforcing device  23 . 
     A heating temperature of the fusion-spliced-portion reinforcing device  23  is generally 230° C. in the second and the third embodiments. The ferrule  40  is housed in the heating chamber  23   a  so that there is a likelihood that an adhesive to fix the inserted built-in optical fiber  43  in the ferrule  40  may melt. In that case, it is preferable that the temperature of the heating chamber  23   a  is a temperature or more for the reinforcing body  48  to become heat-shrinkable and a temperature or less for an adhesive to melt, for example, 120° C. to 160° C. When the holding unit  32  of the ferrule holder  30  is made of a heat-resisting material such as a ceramic in the first embodiment, it is preferably possible to prevent the ferrule  40  in the heating chamber  23   a  from increasing in temperature and an adhesive from melting. 
     The ferrule holder according to the present invention is not limited to the first embodiment and can be implemented in various aspects. The other aspects of the ferrule holder are explained below. 
     For example, as shown in a perspective view of  FIG. 15 , a ferrule holder  70  includes a holder body  71 , a cylindrical holding unit  72  on which a slit is not formed, a stem  73  that is arranged at a rear end  71   b  of the holder body  71 , and a fixing member  74 . The ferrule holder  70  can be made as follows. An inner diameter of the holding unit  72  is larger than the outer diameter of the cylindrical portion of the ferrule. A layer-shaped elastic member  72   c  is mounted on an inner wall of the holding unit  72 . A hole is made by the layer-shaped elastic member  72   c  to have a slightly smaller inner diameter than the outer diameter of the cylindrical portion of the ferrule. The ferrule holder  70  can hold the ferrule while the layer-shaped elastic member  72   c  presses an outer periphery of the cylindrical portion of the ferrule. Therefore, it is possible to mechanically hold the ferrule with an appropriate force without forming a slit on the holding unit  72 . 
     In addition, as shown in a perspective view of  FIG. 16 , a ferrule holder  80  includes a holder body  81 , a holding unit  82  on which a slit  82   a  is formed, and a stem  83  arranged at a rear end  81   b  of the holder body  81 . The holding unit  82  can be caulked by a caulking unit  82   c  and fixed at a front end (not shown) of the holder body  81  in the ferrule holder  80 . It is possible to reduce the number of components in the ferrule holder  80  because a fixing member to fix the holding unit  82  to the holder body  81  is not required. With its easy assembly, the ferrule holder  80  is hardly affected by heat. 
     As shown in a perspective view of  FIG. 17 , a ferrule holder  90  includes a lid-shaped holding unit  92  that has a slightly smaller inner diameter than the outer diameter of the cylindrical portion of the ferrule and a string-shaped stem  93 . The string-shaped stem  93  is inserted into a hole (not shown) formed in a lid  92   a  of the lid-shaped holding unit  92  and is fixed by a method of running an adhesive into the hole. The ferrule holder  90  can be manufactured at a low price by using a ferrule protection cap that is made of elastic materials such as plastic, PVC, rubber, or the like and that is attached to a commercially available optical connector. It is preferable that the ferrule holder  90  functions as a protection cap for a ferrule before and after a fusion splicing operation. 
     As shown in a perspective view of  FIG. 18 , a ferrule holder  100  can be formed in such a manner that a holding unit  102  and a stem  103  are integrally formed of a tube that has a slightly smaller inner diameter than the outer diameter of the ferrule the ferrule holder holds. The ferrule holder  100  has a low component count and is inexpensive. A material of the tube can be, but are not particularly limited to, ones that do not degrade due to a heating temperature in the fusion-spliced portion. PVC, rubber, heat-shrinkable materials, or the like are used. If the stem  103  of the tube that constitutes the ferrule holder  100  is crushed, the crushed stem is preferable because it is hard to become caught by a windshield cover of the fusion-splicing device. 
     As described above, the ferrule transfer method and the ferrule holder according to the present invention are preferably used when the ferrule with a built-in optical fiber that is fusion-spliced with an optical fiber is transferred to the fusion-spliced portion. 
     Additional effects and modified examples can be easily led by those skilled in the art. Therefore, a broader aspect of the present invention is not limited to specific details and representative embodiments that are represented and described above. Hence, various modifications can be made without departing from a spirit or a scope of a comprehensive concept of the invention that is defined by attached claims and their equivalents. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Technology Category: 3