Holder, fusion-splicing apparatus, and manufacturing method of optical connector

A holder capable of protecting an optical connector ferrule from an external shock, or the like and executing a fusion-splice of a short optical fiber not to take out the optical connector ferrule from the holder is obtained.A holder for holding a connector plug equipped with an optical connector ferrule to which a short optical fiber is fitted and a plug frame for covering an outer periphery of the optical connector ferrule therein, wherein, when the short optical fiber together with the holder is fitted to a fusion splicing apparatus that fusion-splices the short optical fiber and other coated optical fiber, the short optical fiber extended from the plug frame is positioned in a fusion position.

TECHNICAL FIELD

The present invention relates to a holder for housing a connector plug having an optical connector ferrule with a short optical fiber to protect it, a fusion splicing apparatus for fusion-splicing the short optical fiber and other coated optical fiber, and an optical connector assembling method of assembling an optical connector by using the holder and the fusion splicing apparatus.

RELATED ART

In the private optical wiring, etc., the optical connector must be fitted to the optical fiber cable in the field.

In the prior art, as one mode of the structure that the optical connector ferrule is connected to the end of the coated optical fiber in the field, there is an optical connector110set forth in Patent Literature 1 (FIG. 25).

In the optical connector110shown herein, a short optical fiber103fitted to an optical connector ferrule102previously are connected to a coated optical fiber100in the field by the fusion splice, and the circumference of a fusion spliced portion105is covered with a protection sleeve101and is reinforced.

This optical connector110is constructed such that a connector housing121houses respective elements from the optical connector ferrule102to a part of the coated optical fiber100located in the rear of the protection sleeve101that covers the fusion spliced portion105therein.

Here, the connector housing121is constructed to have a plug frame122for housing the optical connector ferrule102in a state that its top end is projected, a boot123for housing an end portion of the coated optical fiber100, and a cylindrical stop ring124one end of which is fitted integrally into the plug frame122and the other end of which is fitted integrally into the boot123. Also, the optical connector ferrule102in the plug frame122is energized to the top end side by a compression coil spring125. This compression coil spring125enables the optical connector ferrule102to move back in connecting the connector such that a contact pressure between the optical connector ferrule102and the optical connector ferrule of the opposing optical connector can be kept within a normal range.

The optical connector ferrule102used in the optical connector110needs delicate handling. This is because it should be prevented that the short optical fiber103extended from the optical connector ferrule102is damaged due to the bending action caused in carrying, holding, etc. the ferrule in the site.

Therefore, for the purpose of protecting the optical connector ferrule102and the short optical fiber103in carrying, holding, etc. the ferrule in the site, utilization of the housing case for housing/holding these elements may be thought of.

However, even though the housing case is employed, the optical connector ferrule102must be taken out from the housing case and then set to the fusion splicing apparatus prepared in the field in advance when other coated optical fiber100is fusion-spliced to the short optical fiber103in the field. As a result, it is feared that the optical connector ferrule102or the short optical fiber103is broken down during the handling needed until the optical connector ferrule102is set to the fusion splicing apparatus.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a holder capable of protecting an optical connector ferrule with a short optical fiber from an external shock, or the like and aligning the short optical fiber with a fusion position of a fusion splicing apparatus while holding the optical connector ferrule therein, a fusion splicing apparatus equipped with a fusion processing portion to which the holder that is holding the optical connector ferrule can be fitted and a thermal shrinkage processing portion for causing a thermal shrinkable tube that covers fusion-spliced portions of mutual optical fibers to thermally shrink, and an optical connector assembling method capable of assembling effectively an optical connector by using the holder and the fusion splicing apparatus.

The present invention solves the above problems by employing following configurations in [1] to [14].

[1] A holder for containing an optical connector ferrule to which a short optical fiber is fitted, wherein the holder is constructed to position the short optical fiber extended from the optical connector ferrule and to be fitted to a fusion splicing apparatus that fusion-splices the short optical fiber and other coated optical fiber.

[2] In the holder according to [1], a recess portion for positioning the short optical fiber extended from the optical connector ferrule is provided.

[3] In the holder according to [1], a lid member for pressing the optical connector ferrule is provided to a holder main body in which a ferrule containing portion for containing the optical connector ferrule is formed.

[4] In the holder according to [3], the lid member is formed of transparent material.

[5] In the holder according to [1], the optical connector ferrule to which the short optical fiber is fitted is contained in a mode of a connector plug whose outer periphery is covered with a plug frame.

[6] In the holder according to [5], a V groove for positioning the short optical fiber extended from the plug frame is provided.

[7] In the holder according to [5], a lid member for pressing the plug frame is provided to a holder main body on which a plug housing portion for housing the plug frame therein is formed.

[8] In the holder according to [7], the lid member is formed of a transparent material.

[9] In the holder according to [7], the lid member presses the short optical fiber positioned on the V groove.

[10] A fusion splicing apparatus for fusion-slicing a short optical fiber fitted to an optical connector ferrule and other coated optical fiber, which includes a fusion processing portion equipped with a holder fitting portion that fits the holder according to [1].

[11] In the fusion splicing apparatus according to [10], the fusion splicing apparatus further includes a thermal shrinkage processing portion for heating/shrinking a thermal shrinkable tube that is put on an outer periphery of a fusion spliced portion being formed by the fusion processing portion; wherein the thermal shrinkage processing portion is equipped with a holder fitting portion that fits the holder.

[12] In the fusion splicing apparatus according to [11], the thermal shrinkage processing portion has a first thermal shrinkage processing portion in which a heating temperature distribution is set such that a heating temperature of the thermal shrinkable tube on the short optical fiber side is higher than that on the coated optical fiber side.

[13] In the fusion splicing apparatus according to [12], the thermal shrinkage processing portion has a second thermal shrinkage processing portion in which a heating temperature distribution is set such that a heating temperature of the thermal shrinkable tube on a middle portion side is higher than that on an end portion.

[14] An optical connector assembling method of assembling an optical connector in which other coated optical fiber is fusion-spliced to a short optical fiber, by fusion-splicing the short optical fiber being fitted to an optical connector ferrule to the other coated optical fiber while using the fusion splicing apparatus according to [10], which includes a step of setting the coated optical fiber on a fiber fitting portion of a fusion processing portion of the fusion splicing apparatus; a step of setting a holder that holds a connector plug therein in a holder fitting portion of the fusion processing portion; a step of fusion-splicing the short optical fiber positioned in the holder that is fitted to the holder fitting portion and the coated optical fiber positioned in the fiber fitting portion in the fusion processing portion; a step of forming a fusion spliced portion by fusion-splicing the short optical fiber and the coated optical fiber, and then putting a protection sleeve having a thermal shrinkable tube on the fusion spliced portion; and a step of transferring the fusion spliced portion to the thermal shrinkage processing portion, and then heating the thermal shrinkable tube of the protection sleeve to shrink.

According to the holder of the present invention, when the plug frame fitted onto the optical connector ferrule to which the short optical fiber is fitted is housed in the holder, this holder can protect the optical connector ferrule and the short optical fiber from a shock, etc. applied from the outside.

In addition, this holder can position the short optical fiber being fitted into the optical connector ferrule in a fusion position of the fusion splicing apparatus while holding the plug frame therein. Therefore, the troublesome operation of taking out the connector plug from the holder in the fusion splice can be omitted, and thus the easy handling property at a time of fusion splice can be improved.

According to the fusion splicing apparatus of the present invention, the fusion processing portion equipped with the holder fitting portion to which the holder can be fitted is provided. As a result, the short optical fiber being fitted into the optical connector ferrule can be fusion-spliced to the other coated optical fiber not to pick up the optical connector ferrule from the holder, and the operability in the fusion-splicing operation can be improved.

Also, because the thermal shrinkage processing portion for causing the thermal shrinkable tube that covers the fusion-spliced portions of mutual fibers to thermally shrink is provided in parallel with the fusion processing portion, the thermally shrinking process of the thermal shrinkable tube can be applied not to take out the connector plug from the holder.

According to the optical connector assembling method of the present invention, the optical connector can be assembled effectively by using the holder and the fusion splicing apparatus without damage of the optical connector ferrule and the short optical fiber.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

BEST MODE FOR CARRYING OUT THE INVENTION

Respective preferred embodiments will be explained in detail in order of a holder, a fusion splicing apparatus, and an optical connector assembling method according to the present invention with reference to the drawings hereinafter.

FIG. 1is a perspective view of a first embodiment of a holder according to the present invention, wherein a lid member is opened.FIG. 2is a perspective view showing a state that a cap is fitted onto the holder shown inFIG. 1.FIG. 3is a perspective view showing a state that a lid member of the holder shown inFIG. 1is closed.FIG. 4is a schematic view when viewed from an arrow A inFIG. 3.

A holder51of the first embodiment holds a connector plug10in which a stopper11is fitted into a plug frame9, into which an optical connector ferrule7(seeFIG. 11) described later is fitted, and on which a dust cap22is fitted. Thus, the holder51protects a short optical fiber5fitted to the optical connector ferrule7previously and the connector plug10.

In the holder51of the first embodiment, a foldable lid member56is fitted to a holder main body54on which a plug housing portion53as a recess for housing the plug frame9therein is formed to open upward. The foldable lid member56covers the plug housing portion53to hold the plug frame9contained in the plug housing portion53.

As indicated with a chain double-dashed line inFIG. 2, a box-type cap57is detachably attached to the front end side of the holder main body54from which the short optical fiber5is extended. This box-type cap57covers the surrounding of the short optical fiber extended from the holder main body54to protect the short optical fiber5and the plug frame9.

The cap57may be formed of the antistatic material.

The lid member56is hinged to the rear end portion of the holder main body54via a pivot58that is fitted into the rear end side of the holder main body54. The lid member56when turned around the pivot58is opened/closed in the arrow a direction shown inFIG. 1.

The lid member56is shaped into an almost planar shape that covers the holder main body54. As shown inFIG. 3, a grasping portion56abeing held by worker's fingers in opening/closing operations is provided to both sides respectively to project therefrom.

Also, as shown inFIG. 3, a window hole56bthrough which the worker can view the based end portion and its periphery of the plug frame9housed in the holder main body54is formed in the lid member56to pass therethrough.

In the holder51of the first embodiment, as shown inFIG. 4, a V groove61is provided to an upper end surface of a front end wall54aof the holder main body54through which the short optical fiber5passes. Thus, this V groove61positions and supports the short optical fiber5extended from the plug frame9.

Also, as shown inFIG. 4, the lid member56when is closed presses the short optical fiber5being positioned in the V groove61against the front end wall54a.

In this manner, the holder main body54on which the plug housing portion53is formed, the V groove61formed on the holder main body54, and the lid member56for pressing the short optical fiber5to the V groove61are provided to the holder51. Then, the holder51is fitted to a fusion splicing apparatus71that fusion-splices the short optical fiber5and other coated optical fiber3(seeFIG. 8) in the field, described later. At that time, the holder51can position as it is the short optical fiber5extended from the plug frame9, which is housed in the plug housing portion53, in a fusion position.

According to the holder51of the first embodiment explained above, when the plug frame9fitted onto the optical connector ferrule7, to which the short optical fiber5is fitted in advance, is housed in the holder51, this holder51can protect the optical connector ferrule7and the short optical fiber5from a shock, etc. applied from the outside and also facilitate the handling in carrying, holding, etc. the ferrule in the site.

Also, while holding the plug frame9therein, the holder51can position the short optical fiber5being fitted into the optical connector ferrule7in a fusion position of the fusion splicing apparatus71. Therefore, the troublesome operation of taking out the connector plug10from the holder51in the fusion splice can be omitted, and thus the easy handling property at a time of fusion splice can be improved.

In addition, if this holder51can be fitted to the fusion splicing apparatus that connects the existing coated optical fibers mutually, there is no need to prepare the dedicated fusion splicing apparatus.

Also, in the holder51of the first embodiment, the V groove61for positioning and supporting the short optical fiber5extended from the plug frame9is provided, and also the short optical fiber5extended from the optical connector ferrule7that is housed in this holder51is positioned precisely on the holder51by an action of the V groove61. Therefore, when the holder51is set to the fusion splicing apparatus71, no time and labor to position the short optical fiber5is needed.

Also, the holder51of the first embodiment is constructed by providing the lid member56, on which the plug housing portion53for housing the plug frame9therein is formed to open upward, to the holder main body54that covers the plug housing portion53to press the plug frame9held in the plug housing portion53. Therefore, loading/unloading of the plug frame9into/from the holder51can be executed easily by opening/closing the foldable lid member56.

Also, in the holder51of the first embodiment, not only the V groove61for positioning/supporting the short optical fiber5is provided to the holder main body54on which the plug housing portion53that holds the plug frame9is formed to open upward, but also the lid member56presses the short optical fiber5positioned in the V groove61.

Accordingly, the short optical fiber5extended from the plug frame9that is housed in the holder main body54is positioned by the V groove61, and then is fixed to the V groove61by the lid member56. Therefore, the positioning of the short optical fiber5can be executed without fail.

In addition, it is preferable that a projection portion should be provided to the lid member56on the side that is closer to the end of the short optical fiber5than the V groove61in such a way that this projection portion presses the short optical fiber5toward the V groove61from the upper side and the short optical fiber5is directed obliquely below. This is because, even when the short optical fiber5got kinked, or the like, such short optical fiber5is corrected along the V groove61and is ready to be positioned in the fusion splice.

Also, the window hole56bthrough which the worker can view the based end portion and its periphery of the plug frame9is formed in the lid member56. Therefore, unless the worker does not open the lid member56, such worker can check holding condition, type, etc. of the plug frame9being housed.

In the first embodiment, the window hole56bis provided in the lid member56to facilitate the viewing of the plug frame9being housed in the holder main body54. In this case, instead of the provision of the window hole56b, the lid member56may be formed of the transparent material. When the lid member56is formed of the transparent material in this manner, the worker can check the held plug frame9with his or her eyes not to open the lid member56.

In this case, in the holder according to the present invention, the coupling position of the holder main body54and the lid member56and the opening/closing direction of the lid member56are not restricted to the configurative modes shown in the first embodiment.

FIG. 5is a perspective view of a second embodiment of a holder according to the present invention, wherein the foldable lid member is closed in a state that the cap is removed.FIG. 6is a perspective view showing a state that the lid member of the holder shown inFIG. 5is opened.

A holder63shown herein is common to the first embodiment in that the holder main body54having the plug housing portion53, which houses therein the plug frame9that is fitted onto the optical connector ferrule7described later (seeFIG. 11) while the dust cap22and the stopper11are fitted to this plug frame9, and the lid member56provided foldably to the holder main body54to cover the plug housing portion53are provided.

However, in the case of this holder63, the fitting position and the opening/closing direction of the lid member56are improved. In the case of this holder63, as indicated by an arrow b inFIG. 6, the lid member56can be opened/closed sideward on the pivot58that is fitted into the side end portion of the holder main body54.

In this manner, the fitting position and the opening/closing direction of the lid member56can be changed in design appropriately in response to the holder main body54that houses the plug frame9.

Next, an embodiment of a fusion splicing apparatus according to the present invention will be explained hereunder.

FIG. 7is a perspective view of an embodiment of a fusion splicing apparatus according to the present invention when viewed from obliquely above.FIG. 8is an enlarged view of a fusion processing portion of the fusion splicing apparatus inFIG. 7.FIG. 9is an enlarged view showing a state that the cover of the thermal shrinkage processing portion provided to the fusion splicing apparatus inFIG. 7.

The fusion splicing apparatus71shown inFIG. 7toFIG. 9is such an apparatus that fusion-splices the short optical fiber5being fitted to the optical connector ferrule7to other coated optical fiber3in the site where the construction work to lay the optical fiber cable is carried out.

This fusion splicing apparatus71is equipped with a fusion processing portion74into which a holder fitting portion73fits the short optical fiber5housed in the holder51together with the holder51to position the fiber in a fusion position to the other coated optical fiber3is installed, and a thermal shrinkage processing portion76for thermally shrinking a thermal shrinkable tube25coated on an outer periphery of a fusion spliced portion13(seeFIG. 13), which fusion-splices the short optical fiber5being fusion-spliced by the fusion processing portion74to the other coated optical fiber3, by a heater.

The fusion processing portion74is provided to an upper surface portion of the apparatus that is covered with a foldable cover77.

As shown inFIG. 8, the fusion processing portion74has a fiber fitting portion78for setting the other coated optical fiber3in the site, a V-groove member79arranged at the top end of the fiber fitting portion78to position a top end position of the coated optical fiber3being set on the fiber fitting portion78, a V-groove member81for positioning a top end position of the short optical fiber5extended from the holder51being set to the holder fitting portion73, and a pair of electrodes83arranged to the V-groove members79,81respectively to fusion-weld mutual butted optical fibers by the electric discharge.

Dimensions of the V-groove member81for positioning the short optical fiber5and the V groove61of the holder51being set in the holder fitting portion73are set to support/align the short optical fiber5on a straight line.

The holder51may be fitted previously in the holder fitting portion73. In this case, the worker picks up the connector plug10housed in another case and then puts this plug in the holder51being set in the holder fitting portion73.

The thermal shrinkage processing portion76has a particular foldable cover84, and equipped adjacently to the fusion processing portion74.

As shown inFIG. 9, when the foldable cover84is opened, two thermal shrinkage processing portions of a first thermal shrinkage processing portion86and a second thermal shrinkage processing portion87provided in parallel appear.

The first and second thermal shrinkage processing portions86,87have a different heating temperature distribution described later respectively, but both portions are formed in the same configuration. Therefore, only the first thermal shrinkage processing portion86will be explained herein.

The first thermal shrinkage processing portion86is equipped with a heating portion88to which a heater (not shown) for heating the thermal shrinkable tube25is provided, a holder fitting portion89for positioning/fitting the holder51that contains the connector plug10, and a fiber-fitting portion90.

Although omitted from the holder fitting portion89inFIG. 9, a foldable cover91for inhibiting the coming-out of the coated optical fiber and the plug frame9is fitted to the holder fitting portion89and the fiber fitting portion90respectively.

In the first thermal shrinkage processing portion86, a heating temperature distribution of the heater is set such that a heating temperature of the thermal shrinkable tube25on the short optical fiber5(the connector plug10) side is higher than that on the coated optical fiber3side.

In the second thermal shrinkage processing portion87, a heating temperature distribution of the heater is set such that a heating temperature of the thermal shrinkable tube25on the middle portion side is higher than that on the end portion.

The first thermal shrinkage processing portion86is the configuration that is suitable for a protection sleeve15in which an end portion of the thermal shrinkable tube25is connected to a coupling component31, or the like described later. The heating temperature distribution is given to the heater such that first the short optical fiber side is heated to cause the shrinkage and then the other optical fiber side is heated to cause the shrinkage. Therefore, voids generated in the thermal shrinkable tube25at a time of heating are ready to come out of the end portion on the other optical fiber side.

Also, if the second thermal shrinkage processing portion87is provided, the heating process can be applied even when the ordinary coated optical fibers are to be connected mutually. In this case, the heating temperature distribution is given to the heater such that the center portion of the thermal shrinkable tube25is heated at a high temperature to cause the shrinkage and then the end portion is heated to cause the shrinkage. Therefore, voids generated in the thermal shrinkable tube25at a time of heating are ready to come out of both end portions.

The fusion splicing apparatus71explained above is equipped with the fusion processing portion74into which the holder fitting portion73to which the holder51that housed the optical connector ferrule7therein can be fitted is installed. As a result, the short optical fiber5being fitted into the optical connector ferrule7can be fusion-spliced to the other coated optical fiber3not to pick up the optical connector ferrule7from the holder51, and the operability in the fusion-splicing operation can be improved.

Also, because the thermal shrinkage processing portion76for causing the thermal shrinkable tube25that covers the fusion-spliced portions of mutual fibers to thermally shrink is provided in parallel with the fusion processing portion74, the thermally shrinking process of the thermal shrinkable tube25can be applied quickly on the same fusion splicing apparatus71. In this case, because the thermal shrinkage processing portion76is equipped with the holder fitting portion89, to which the holder51that held the connector plug10therein can be fitted, similarly to the holder fitting portion73in the fusion processing portion74, the thermal shrinkable tube25on the fusion spliced portion13extended from the holder51can be thermally shrunk at an adequate heating temperature distribution by arranging/positioning the holder51in the holder fitting portion89after the fusion process.

Also, because the second thermal shrinkage processing portion87having a heating temperature distribution already described is provided, one fusion splicing apparatus can be used commonly in the connection between the short optical fiber having the connector plug and the other coated optical fiber, the fusion splice between the coated optical fibers, and the heating process of the thermal shrinkable tube after both fibers are connected. Therefore, there is no necessity to prepare the dedicated fusion splicing apparatus.

In addition, in the case of the fusion splicing apparatus71, two thermal shrinkage processing portions76each having a different heating temperature distribution of the heater that heats the thermal shrinkable tube25are provided as the thermal shrinkage processing portion76. Therefore, the heating process to meet the fitting mode of the thermal shrinkable tube25can be carried out by selecting either of the thermal shrinkage processing portions76.

In respective embodiments of the holder, such a configuration is shown that the lid member is fitted to the holder main body. However, the foldable cover of the fusion splicing apparatus can be used commonly as this lid member.

Next, an optical connector assembling method according to the present invention will be explained with reference toFIG. 10toFIG. 14andFIG. 16hereunder.

FIG. 10is a perspective exploded view showing a schematic configuration of the optical connector that is assembled by using the fusion splicing apparatus inFIG. 7.FIG. 11is a perspective exploded view of a connector plug shown inFIG. 10.FIG. 12is a perspective exploded view of a protection sleeve and a rear housing shown inFIG. 10.FIG. 13is an enlarged side view of the protection sleeve shown inFIG. 12.FIG. 14is a sectional view taken along a B-B line inFIG. 13.FIG. 15is an explanatory view showing procedures of the optical connector assembling method according to the present invention.FIG. 16is a longitudinal sectional view of the optical connector that is completed by the optical connector assembling method inFIG. 15.

An optical connector1is fitted to the end portion of the coated optical fiber3in the field. As shown inFIG. 10, the optical connector1includes the connector plug10in which the optical connector ferrule7is fitted into the plug frame9, an SC connector knob33fitted onto the outer periphery of the connector plug10, the protection sleeve15for covering the circumference of the fusion spliced portion13(seeFIG. 13) between the short optical fiber5fitted to the optical connector ferrule7and the coated optical fiber3in the field, a rear housing18which has an internal space17in which the protection sleeve15is arranged and whose top end is coupled integrally to the plug frame9, and a boot21which houses the end portion and its neighborhood of the coated optical fiber3being fusion-spliced to the short optical fiber5therein to protect the coated optical fiber3and whose top end is coupled integrally to the base end of the rear housing18.

As shown inFIG. 11, the connector plug10has the optical connector ferrule7to which the short optical fiber5is fitted in advance, the plug frame9that houses/holds the optical connector ferrule7, the almost cylindrical stopper11which is fitted into the opening of the plug frame9on the base end side and into which the optical connector ferrule7is inserted, a ferrule press spring23fitted between the stopper11and a diameter-enlarged portion7bof the optical connector ferrule7in its compressed mode to support elastically the optical connector ferrule7in the plug frame9to retreat, and the dust cap22fitted to the top end side of the plug frame9to cover a top end shaft portion7aof the optical connector ferrule7projected from the top end of the plug frame9.

The connector plug10is contained/held in the above holders51,63.

The optical connector ferrule7has such a shape that the diameter-enlarged portion7bwhose diameter is enlarged is provided at the back of the top end shaft portion7athat is butt-connected to the opposing optical connector ferrule. The short optical fiber5is fitted such that its center axis agrees with the top end shaft portion7a. Also, as shown inFIG. 11, a sleeve coupling projection7cto which the protection sleeve15is coupled is provided on the outer periphery of the optical connector ferrule7on the base end side from which the short optical fiber5is protruded.

When the optical connector ferrule7is inserted into opening on the basal end side of the plug frame9, the front end of the diameter-enlarged portion7bcontacts a diameter-contracted portion9aprojected from the inner periphery of the plug frame9to restrict its forward movement, as shown inFIG. 16. In this condition, as shown inFIG. 16, a position of the optical connector ferrule7is restricted such that the top end of the optical connector ferrule7is protruded from the top end of the plug frame9by a predetermined length L1.

Then, as described above, in order to prevent that a dust, and the like adhere to the fiber end surface in keeping the optical fiber, and the like, the dust cap22is put on the top end of the optical connector ferrule7that is positioned in the plug frame9.

As shown inFIG. 13, the fusion spliced portion13is formed by causing an uncoated portion5bfrom which a coating5ain the end portion of the short optical fiber5is peeled off and an uncoated portion3bfrom which a coating3ain the end portion of the coated optical fiber3is peeled off to butt to each other, and then fusion-splicing the butted fiber end surfaces mutually.

As shown inFIG. 12toFIG. 14, the protection sleeve15has the thermal shrinkable tube25, a core rod27passed through the thermal shrinkable tube25and an adhesive tube29, and the coupling component31secured to one end of the thermal shrinkable tube25. The coupling component31is coupled to the optical connector ferrule7.

The thermal shrinkable tube25, when heated up to a predetermined temperature by the heater, causes the thermal shrinkage and is tightly adhered to the core rod27passing therethrough.

As shown inFIG. 13andFIG. 14, the core rod27is a solid round rod whose cross sectional shape is a circle, and is passed through the thermal shrinkable tube25as a reinforcing core material. As the core rod27, a steel wire, a glass, and the like can be employed.

The adhesive tube29is the tube that is made of an adhesive agent and is inserted into the thermal shrinkable tube25along with the core rod27longitudinally. The adhesive tube29is softened by the heating being applied in thermally shrinking the thermal shrinkable tube25, and acts as an adhesive to fill a clearance34between the thermal shrinkable tube25and the core rod27shown inFIG. 14.

The protection sleeve15positions at first the thermal shrinkable tube25, the core rod27, and the adhesive tube29in a state that the end portion of the core rod27and the end portion of the adhesive tube29protrude from one end of the thermal shrinkable tube25by a predetermined length L2, shown inFIG. 13. The base end of the coupling component31is secured to one end of the thermal shrinkable tube25in this positioning state.

When end portions of the thermal shrinkable tube25and the core rod27are press-fitted, adhered, or deposited to the coupling component31, this coupling component31is fixed integrally to the thermal shrinkable tube25and the core rod27.

As shown inFIG. 13, in the coupling component31, an end portion on the optical connector ferrule7side is shaped into a cylinder portion31athat is fitted onto the base end of the optical connector ferrule7. An engaging hole31bwith which the sleeve coupling projection7cof the optical connector ferrule7is engaged is formed in this cylinder portion31a.

One end of the protection sleeve15is coupled integrally with the optical connector ferrule7by engaging the sleeve coupling projection7cwith the engaging hole31b.

When the optical connector1is assembled, the coated optical fiber3is passed previously through the protection sleeve15as well as the rear housing18and the boot21, as shown inFIG. 15(b), and the protection sleeve15is replaced on the coated optical fiber3after the coated optical fiber3and the short optical fiber5are fusion-spliced. Then, length dimensions of the short optical fiber5and the protection sleeve15are set with respect to the thermal shrinkable tube25, the core rod27, and the adhesive tube29such that the fusion spliced portion13is positioned just in an almost middle position of the protection sleeve15in the longitudinal direction when the coupling component31is coupled to the base end of the optical connector ferrule7.

In more precisely speaking, the protection sleeve15is moved onto the fusion spliced portion13to cover the fusion spliced portion13after the short optical fiber5and the coated optical fiber3are fusion-spliced, then the coupling component31of the protection sleeve15is coupled to the optical connector ferrule7, and then the coated optical fiber3and the short optical fiber5around the fusion spliced portion13are secured along the core rod27longitudinally by heating the thermal shrinkable tube25.

In the case of the present embodiment, diameter dimensions of the coupling component31, the core rod27, and the like are set such that fiber positions of the short optical fiber5and the coated optical fiber3being arranged in the protection sleeve15agree with an axis center of the optical connector ferrule7in a state that the thermal shrinkable tube25has been thermally shrunk.

The rear housing18is a cylindrical structural body for covering the circumference of the protection sleeve15, and is formed by the resin injection molding, or the like. A top end of the rear housing18is shaped into a cylinder portion18athat is fitted onto the base end of the plug frame9. Then, an engaging hole18bthat engages with an engaging claw (not shown) formed on the outer periphery of the based end of the plug frame9to project when this cylinder portion18ais fitted onto the base end of the plug frame9is provided to this cylinder portion18a.

The above rear housing18is put on the protection sleeve15after the thermal shrinking process of the protection sleeve15. Then, the rear housing18is coupled integrally to the plug frame9when the engaging hole18bon the top end side is engaged with the engaging claw of the plug frame9.

In the case of the present embodiment, the SC connector knob33serving as a knob portion in the connector connection is put/fitted on the outer periphery of the plug frame9to which the rear housing18is coupled. This SC connector knob33is the enclosure member that provides an external appearance of the optical connector1on the top end side. A non-slip serrated portion33afor easy grasping is formed on the outer surface of the SC connector knob33.

The boot21protects the coated optical fiber3such that a sharp bending is not applied to the coated optical fiber3that extended to the rear side of the rear housing18. The boot21is coupled integrally with the rear housing18when its top end is tightly fitted to or screwed into the base end of the rear housing18.

Alternatively, the boot may be formed integrally with the rear housing18by injection molding of a resin.

In the case of the present embodiment, as shown inFIG. 16, a space35for enabling the protection sleeve15to retreat is created between other end15aof the protection sleeve15and an inner wall end21aof the boot21opposing to this other end15a.

Further, as shown inFIG. 12andFIG. 16, a reinforcing tube37that is put on the coated optical fiber3is inserted/fitted to the back of the inner wall end21aof the boot21.

A disconnection-preventing portion37awhose diameter is enlarged is provided to the top end of the reinforcing tube37. A backward movement of the boot21is restricted when the disconnection-preventing portion37ais latched. The reinforcing tube37is a tube that has an adequate elasticity and prevents that the coated optical fiber3is bent sharply.

Next, a method of assembling the optical connector1shown inFIG. 16by using the holder51and the fusion splicing apparatus71explained above will be explained hereunder.

In this assembling method, as shown inFIG. 15(a), the holder51in which the connector plug10is housed is prepared previously. Also, as shown inFIG. 15(b), the coated optical fiber3in the field is passed through the protection sleeve15, the rear housing18, and the boot21.

Then, as shown inFIG. 8, a step of setting the coated optical fiber3on the fiber fitting portion78of the fusion processing portion74in the fusion splicing apparatus71and a step of setting the short optical fiber5in which the connector plug10is housed on the holder fitting portion73of the fusion processing portion74are executed.

Then, the short optical fiber5positioned in the holder51being fitted to the holder fitting portion73and the coated optical fiber3positioned on the fiber fitting portion78are fusion-spliced to each other in the fusion processing portion74.

Then, the fusion spliced portion13is formed by fusion-splicing the short optical fiber5and the coated optical fiber3, and then the connector plug10is taken out from the holder51. Then, as shown inFIG. 15(c), the protection sleeve15having the thermal shrinkable tube25is put on the fusion spliced portion13, and the coupling component31formed on one end of the protection sleeve15is coupled to the plug frame9. Thus, a step of obtaining a sleeve-plug coupled body16in which one end of the protection sleeve15is coupled to the plug frame9is carried out.

Also, the sleeve-plug coupled body16is transferred to the first thermal shrinkage processing portion86of the thermal shrinkage processing portion76, and the thermal shrinkable tube25of the protection sleeve15is thermally shrunk. Thus, a step of obtaining a structural body19in which the fusion spliced portion13is reinforced by the thermal shrinkable tube25being shrunk, as shown inFIG. 15(d), is carried out.

Then, the rear housing18and the boot21through which the coated optical fiber3is passed previously are coupled to the plug frame9of the structural body19. Thus, a completed structure shown inFIG. 15(e) can be obtained.

According to the above optical connector assembling method, the optical connector1can be assembled effectively by using the holder51and the fusion splicing apparatus71without damage of the optical connector ferrule7and the short optical fiber5.

Next, a third embodiment of the holder and the fusion splicing apparatus according to the present invention will be explained hereunder.

First, prior to explanation of the holder and the fusion splicing apparatus, the optical connector used in the holder of the present embodiment will be explained hereunder.

FIG. 17is an exploded side view of an optical connector used in the third embodiment of the present invention. In this case, in the present embodiment, explanation will be made by affixing the same symbols to the same member and the same portion in the above embodiment.

The optical connector can be applied to both the fiber cord type to which an optical fiber cord70is connected and the coated fiber type to which the coated optical fiber3is connected. The coated fiber type optical connector uses substantially common components to the fiber cord type optical connector except that a shape of the Sc connector knob is slightly different. In the following explanation, mainly a fiber cord type optical connector (referred simply to as an “optical connector” hereinafter)1B will be explained.

The optical connector1B has an Sc connector knob181, a plug frame183, a fiber built-in ferrule (optical connector ferrule)185, a protection sleeve187, a ferrule set spring189, a rear housing191, a caulking ring193, and a boots195as major members from the top end side (the left side inFIG. 18) to which the counter side optical connector is coupled. That is, the structure in which the stopper11and the coupling component31explained in the above embodiment are not used is shown.

FIG. 18(a) is a longitudinal sectional view of the optical connector shown inFIG. 17, andFIG. 18(b) is a longitudinal sectional view of a pertinent portion of a variation in which a reinforcing tube is fitted.

The optical connector ferrule185is constructed by fitting an diameter-enlarged portion7bwhose outer diameter is enlarged to the back side of a top end shaft portion7ato which the optical connecter ferrule on the other side is butted and connected, and the short optical fiber5is fitted to the optical connector ferrule185such that its center axis is aligned with the top end shaft portion7a. Also, a sleeve coupling projection7cto which the protection sleeve187described later is coupled is provided to an outer periphery of the optical connector ferrule185on the base end side from which the short optical fiber5is extended.

When the optical connector ferrule185inserted into an opening of the plug frame183on the base end side, the diameter-contracted portion9aprovided to an inner periphery of the plug frame183to protrude is brought into contact with the front end of the diameter-enlarged portion7b, as shown inFIG. 19, and thus a forward movement of this ferrule185is restricted. In this state, a position of the optical connector ferrule185is fixed in the position that the top end of the optical connector ferrule185protrudes from the top end of the plug frame183by a predetermined length L1.

In order to prevent adhesion of the dust, etc. to a fiber end surface during the storage, the dust cap22(seeFIG. 2) is put on a top end of the optical connector ferrule185that has been positioned in the plug frame183.

In this case, the top end surface of the optical connector ferrule185is mirror-polished previously to omit the polishing on the job site.

The ferrule set spring189is inserted in the plug frame183into which the optical connector ferrule185is inserted. This ferrule set spring189is a compression coil spring that is put and held between the rear housing191, which is engaged with the plug frame183and described later, and the diameter-enlarged portion7bof the optical connector ferrule185. The ferrule set spring189brings the diameter-enlarged portion7bof the optical connector ferrule185into contact with the above diameter-contracted portion9aof the plug frame183, and also elastically support the diameter-enlarged portion7bretractably.

FIG. 19(a) is a sectional view of an optical connector ferrule shown inFIG. 20, andFIG. 19(b) is a longitudinal sectional view of a thermal shrinkable tube connected to the optical connector ferrule.

The fusion spliced portion13is formed by butting an end portion5b, from which a coating5ais striped off, of the short optical fiber5and an end portion3b, from which a coating3ais striped off, of the coated optical fiber3and then fusing the mutual butted fiber end surfaces.

In this case, the end surface of the short optical fiber5, from which the coating5ais striped off, is mirror-processed previously by either the cleavage caused when the optical fiber is cut by applying a bending stress to this fiber or the polishing to neglect the mirror processing on the job site.

Also, preferably an edge of the end surface of the short optical fiber5should be chamfered by the electrical discharge process prior to the fusion splicing, for the chipping generated from the edge by the polishing can be prevented. Also, preferably the carbon coated fiber should be employed as the short optical fiber5, for a reduction of strength caused due to a scratch or a moisture absorption generated in carrying the optical fiber in a coating removed state to the job site can be suppressed. Also, preferably the short optical fiber5should be formed of the fiber that is strong against the bending having a small MFD.

As shown inFIG. 19, the protection sleeve187is equipped with the thermal shrinkable tube25and the core rod27and the adhesive tube (seeFIG. 14) that are inserted into the thermal shrinkable tube25. The thermal shrinkable tube25is coupled to the optical connector ferrule185. The coated optical fiber3is fitted into the optical connector1B in a state that an outer coating72is removed from the end portion of the optical fiber cord70by a predetermined length. The protection sleeve187covers the outer periphery of the coated optical fiber3on the other end side where this fiber is not coupled to the optical connector ferrule185.

The thermal shrinkable tube25thermally shrinks when it is heated at a predetermined temperature by the heating machine, and is tightly adhered to the core rod27that is inserted into this tube.

The adhesive tube29is softened by the heating applied when the thermal shrinkable tube25is cause to thermally shrink, and acts as the adhesive to bury a clearance34between the thermal shrinkable tube25and the core rod27.

The thermal shrinkable tube25, the core rod27, and the adhesive tube29are positioned with respect to one end of the protection sleeve187such that the end portion of the core rod27is aligned with the end portion of the adhesive tube29. Then, the protection sleeve187is secured to the sleeve coupling projection7cof the optical connector ferrule185under this positioned condition.

When the end portions of the thermal shrinkable tube25and the core rod27are press-fitted or adhered or deposited to the optical connector ferrule185, this optical connector ferrule185is fixed/integrated with the tube25and the core rod27.

Respective length dimensions of the short optical fiber5and the thermal shrinkable tube25, the core rod27and the adhesive tube29of the protection sleeve187are set such that, when the protection sleeve187is coupled to the sleeve coupling projection7con the base end of the optical connector ferrule185, the fusion spliced portion13can be just positioned in an almost middle position of the protection sleeve187in the length direction.

After the short optical fiber5and the coated optical fiber3are fusion-spliced, the protection sleeve187is moved to cover the fusion spliced portion13and to contact the optical connector ferrule185. Then, the coated optical fiber3and the short optical fiber5are fixed by applying a heat to the thermal shrinkable tube25in a state that they are positioned vertically along the core rod27.

In this manner, dimensions of respective components are set such that, when the thermal shrinkable tube25is cause to thermally shrink, the end portion of the thermal shrinkable tube25overlaps with the coating3aof the coated optical fiber3and the sleeve coupling projection7cby 2 mm or more.

The rear housing191is a cylindrical structural body for covering the periphery of the protection sleeve187, and is formed by the resin injection molding, or the like. A top end of the rear housing191is shaped into a cylinder portion191athat is fitted into the base end of the plug frame183. An engaging claw191bfor engaging with an engaging hole183aformed on the outer periphery on the base end of the plug frame183when the rear housing191is fitted into the base end of the plug frame183is provided to this cylinder portion191a.

The above rear housing191is moved on the protection sleeve187and put thereon after the thermal shrinkage process of the protection sleeve187. Then, the rear housing191is coupled integrally with the plug frame183by engaging the engaging claw191bon the top end side with the engaging hole183aof the plug frame183.

An SC connector knob181serving as a knob portion when the connector is coupled is put/fitted to the outer periphery of the plug frame183to which the rear housing191is fitted. This SC connector knob181is an outer fitting member that provides an external appearance of the optical connector1B on the top end side. A non-slip serrated pattern33afor easy grasping is formed on the outer side surface of this knob.

The boots195protects the optical fiber cord70not apply a sharp bending to the optical fiber cord70that extends to the rear side of the rear housing191. When a top end of the boots195is fitted to or screwed into the base end of the rear housing191, the boots195is coupled integrally to the rear housing191.

In this case, the boots195may be formed integrally with the rear housing191by the resin injection molding.

The space35(seeFIG. 18) for allowing retreat of the protection sleeve187is formed between the other end187a(seeFIG. 19) of the protection sleeve187and the inner wall end opposing to this other end187ain the boots195.

In this case, as shown inFIG. 18(b), the boots195may have such a structure that the reinforcing tube37that is put on the optical fiber cord70is inserted/fitted to the rear side of the inner wall end.

A slip-off preventing portion37awhose diameter is expanded toward the top end is provided to the reinforcing tube37. When the slip-off preventing portion37ais latched on the inner wall end of the boots195, its backward movement is restricted. The reinforcing tube37is a tube having an adequate elasticity to prevent that the optical fiber cord70is bent sharply.

In the optical connector1B, the outer coating72is stripped off largely from the end portion of the optical fiber cord70to provide the good fusion splicing operation when the short optical fiber5of the optical connector ferrule185is fusion-spliced to the coated optical fiber3being exposed by removing the outer coating72of the optical fiber cord70on the job site. The coated optical fiber3whose outer periphery is covered with a high tensile fiber (Kevlar)174is exposed from the optical fiber cord70when the outer coating72is stripped off (removed) from the end portion.

The high tensile fiber174and the outer coating72are cut in a predetermined length, and inserted on a rear end portion191cof the rear housing191. The caulking ring193is put on the outer periphery of the outer coating72, and the caulking ring193is caulked to reduce the diameter. Since the diameter of the caulking ring193is reduced, the outer coating72and the high tensile fiber174are press-fitted into the caulking ring193and the rear end portion191cand secured to the rear housing191.

Next, the holder according to the present embodiment will be explained hereunder.

FIG. 20is a perspective view of a third embodiment of the holder according to the present invention,FIG. 21is a plan view showing a state that a lid member of the holder shown inFIG. 20is closed, andFIG. 22is a front view of the holder shown inFIG. 21.

A holder151of the third embodiment holds the optical connector ferrule185(seeFIG. 17) in a state that the dust cap22is put, and protects the optical connector ferrule185.

In the holder151of the present embodiment, a foldable lid member156is provided to a holder main body154in which a ferrule containing portion153as the recess for containing the optical connector ferrule185is formed to open upward. This lid member156covers the ferrule containing portion153, and presses the optical connector ferrule185contained in the ferrule containing portion153.

The box-like cap57(seeFIG. 2) is detachably coupled to the front end side of the holder main body154from which the short optical fiber5extends. The box-like cap57covers the periphery of the short optical fiber5extended from the holder main body154to protect the short optical fiber5.

The cap57should be formed of the antistatic material.

The lid member156is hinged to the side portion of the holder main body154around a turning/supporting shaft158being fitted to the side portion of the holder main body154. The lid member156is opened/closed in the arrow c direction shown inFIG. 20based on the turning operation around the turning/supporting shaft158.

The lid member156is shaped into an almost flat plate that is put on the holder main body154. As shown inFIG. 20, a grasping portion156athat the worker grasps by fingers in opening/closing operations is projected from its one side portion.

Also, as shown inFIG. 21, a front end portion156bof the lid member156is formed such that the operator can view the base end portion and its neighborhood of the optical connector ferrule185contained in the holder main body154.

As shown inFIG. 22, in the holder151of the present embodiment, a recess portion161is provided to an upper end surface of a front end wall154aof the holder main body154. This recess portion161is used to position/support the sleeve coupling projection7cof the optical connector ferrule185. The short optical fiber5protrudes coaxially from the sleeve coupling projection7c, as described above.

Also, as shown inFIG. 22, the lid member156, when closed, presses/holds the optical connector ferrule185via the dust cap22and thus positions the sleeve coupling projection7cin the recess portion161. In this case, it is of course that the lid member156may be formed to directly press/hold the optical connector ferrule185. Also, a length of the ferrule containing portion153in the axial direction is almost equal to a length from a front end of the diameter-enlarged portion7bof the optical connector ferrule185to a rear end of the dust cap22. Accordingly, the optical connector ferrule185on which the dust cap22is put is housed without the play in the axial direction. In this holder151, when the front end of the diameter-enlarged portion7bis brought into contact with the front inner wall of the ferrule containing portion153, a projection length L2(seeFIG. 21) of the short optical fiber5is set to about 10 mm. That is, a relative position of the short optical fiber5to the holder151is decided.

When the holder151is fitted to a fusion splicing apparatus171that fusion-splices other coated optical fiber3(seeFIG. 23) on the job site, described later, the short optical fiber5protruded from the optical connector ferrule185that is contained in the ferrule containing portion153is positioned in the fusion splicing position as it is.

According to the holder151of the third embodiment explained as above, when the optical connector ferrule185to which the short optical fiber5is fitted in advance is contained in the holder151and the cap57is put thereon, the holder151protects the optical connector ferrule185and the short optical fiber5from the impact, etc. applied from the outside.

In addition, the holder151can position the short optical fiber5while containing the optical connector ferrule185as it is in the fusion splicing position of the fusion splicing apparatus171. Therefore, the holder151can improve the handling property in the fusion splicing operation.

Also, only when the holder151is fitted to the fusion splicing apparatus171, there is no need to prepare the dedicated fusion splicing apparatus for connecting the existing coated optical fibers mutually.

Also, the recess portion161for positioning/supporting the extended short optical fiber5is provided to the holder151of the present embodiment. The short optical fiber5protruded from the optical connector ferrule185that is contained in the holder151is positioned precisely on the holder151. Therefore, when the holder151is set in the fusion splicing apparatus171, a time and labor required for positioning the short optical fiber5is not needed.

Also, the holder151of the present embodiment is constructed such that the lid member156for pressing the optical connector ferrule185being contained in the ferrule containing portion153is provided to the holder main body154in which the ferrule containing portion153that contains the optical connector ferrule185therein is formed to open upwardly. Therefore, the optical connector ferrule185can be easily put in or taken out from the holder151by opening/closing the foldable lid member156.

Also, the short optical fiber5extended from the optical connector ferrule185that is housed in the holder main body154is positioned by the recess portion161, and then the optical connector ferrule185is fixed by the lid member156. Therefore, the positioning of the short optical fiber5can be executed without fail.

Also, the front end portion156bthrough which the base end portion and its neighborhood of the optical connector ferrule185can be viewed is formed in the lid member156. Therefore, the operator can check the contained state, the type, etc. of the contained optical connector ferrule185not to open the lid member156.

In this embodiment, in order to make it easy to view the optical connector ferrule185contained in the holder main body154, the front end portion156bis provided to the lid member156. Alternately, the lid member156may be formed of the transparent material in place of the formation of the front end portion156b. Even when the lid member156is formed of the transparent material in this manner, the operator can check the contained optical connector ferrule185with the eyes not to open the lid member156.

Next, an embodiment of the fusion splicing apparatus using the holder151will be explained hereunder.

FIG. 23is a perspective view of a fusion splicing apparatus according to the present embodiment when viewed from the obliquely above side, andFIG. 24is an enlarged view of the fusion splicing apparatus inFIG. 23in a state that a cover of a thermal shrinkage processing portion is removed.

The fusion splicing apparatus171is the apparatus that fusion-splices the short optical fiber5fitted previously to the optical connector ferrule185to other coated optical fiber3on the job site where the optical fiber provision work is carried out.

This fusion splicing apparatus171is equipped with a fusion processing portion174and a thermal shrinkage processing portion176. This fusion processing portion174is equipped with a holder fitting portion173that positions the short optical fiber5in a fusion splicing position to other coated optical fiber3by fitting the short optical fiber5contained in the above holder151together with the holder. This thermal shrinkage processing portion176causes the thermal shrinkable tube25, which is put on the outer periphery of the fusion spliced portion13(seeFIG. 19) between the short optical fiber5and other coated optical fiber3both being fusion-spliced by the fusion processing portion174, to shrink by the heater.

Normally the fusion processing portion174is provided to the upper surface portion of the apparatus that is covered with a foldable cover177.

As shown inFIG. 24, the fusion processing portion174includes a fiber fitting portion178to which other coated optical fiber3is set on the job site, the V-groove member79arranged at the top end of the fiber fitting portion178to position a top end position of the coated optical fiber3being set in the fiber fitting portion178, the V-groove member81for positioning a top end position of the short optical fiber5extended from the holder151being set in the holder fitting portion173, and the electrode83arranged between a pair of V-groove members79,81to fusion-splice the mutually butted fibers by the discharge.

Respective dimensions of the V-groove member81for positioning the short optical fiber5and the recess portion161of the holder151being set in the holder fitting portion173are set such that they support/position the short optical fiber5on a straight line.

The holder fitting portion173may be equipped previously with the holder. In this case, the optical connector ferrule185housed in another case is picked up and then is housed in the holder151being set in the holder fitting portion173.

The thermal shrinkage processing portion176has a dedicated opening/closing cover184, and is equipped adjacent to the fusion processing portion174.

As shown inFIG. 24, a thermal shrinkage processing portion186is provided when the opening/closing cover184is opened.

The thermal shrinkage processing portion186is equipped with a heating portion88in which a heater (not shown) for heating the thermal shrinkable tube25is provided, a ferrule fitting portion189for positioning the optical connector ferrule185taken out from the holder151and fitting it, and a fiber fitting portion90.

A foldable cover91for pressing a jumping-out of the coated optical fiber is fitted to the ferrule fitting portion189and the fiber fitting portion90.

A heating temperature distribution of the heater is set in the thermal shrinkage processing portion186such that a heating temperature on the short optical fiber5side of the thermal shrinkable tube25is set higher than that on the coated optical fiber3side.

The thermal shrinkage processing portion186has the configuration that is suitable for the protection sleeve187in which the end portion of the thermal shrinkable tube25is connected to the sleeve coupling projection7cof the optical connector ferrule185. Since the heating temperature distribution is provided to the heater such that first the short optical fiber5side is heated at a high temperature to shrink and then the coated optical fiber3side is caused to shrink, a vapor generated due to the shrinkage and remaining in the thermal shrinkable tube25is ready to escape from the end portion of the coated optical fiber3side.

The fusion splicing apparatus171explained above is equipped with the fusion processing portion174to which the holder fitting portion173to which the holder151containing the optical connector ferrule185is fitted is provided. Therefore, the short optical fiber5fitted to the optical connector ferrule185and other coated optical fiber3can be fusion-spliced mutually not to pick up the optical connector ferrule185from the holder151, and operability in the fusion splicing operation can be improved.

In respective embodiments of the holder, the lid member is provided to the holder main body. But the foldable cover of the fusion splicing apparatus may be used commonly as this lid member.

Next, an assembling method of the optical connector1B shown inFIG. 17by using the holder151and the fusion splicing apparatus171will be explained-hereunder.

In this assembling method, the holder151containing the optical connector1B and shown inFIG. 21is prepared previously. Also, the coated optical fiber3on the job site are inserted into the protection sleeve187, the rear housing191, and the boots195.

Then, as shown inFIG. 23, the step of setting the coated optical fiber3in the fiber fitting portion178of the fusion processing portion174of the fusion splicing apparatus171and the step of setting the holder151in which the optical connector ferrule185is housed to the holder fitting portion173of the fusion processing portion174are carried out.

Then, the short optical fiber5positioned in the holder151fitted to the holder fitting portion173and the coated optical fiber3positioned in the fiber fitting portion178are fusion-spliced in the fusion processing portion174.

Then, the fusion spliced portion13is formed by fusion-splicing the short optical fiber5and the coated optical fiber3, and then the optical connector ferrule185is taken out from the holder151. Then, as shown inFIG. 24, the steps of obtaining a ferrule/sleeve coupled body201by moving the protection sleeve187having the thermal shrinkable tube25onto the fusion spliced portion13and then inserting the sleeve coupling projection7cof the optical connector ferrule185into one end of the protection sleeve187are carried out.

Also, the ferrule/sleeve coupled body201is transferred to the thermal shrinkage processing portion186to cause the thermal shrinkable tube25of the protection sleeve187to thermally shrink. Thus, as shown inFIG. 19, the steps of obtaining the structure in which the fusion spliced portion13is reinforced by the thermal shrinkable tube25are carried out.

Then, a completed structure shown inFIG. 18is obtained by coupling the plug frame183and the rear housing191and the boots195, through which the coated optical fiber3is passed previously, to the optical connector ferrule185built up as the structure.

According to the above optical connector assembling method, the optical connector1B can be assembled effectively by using the holder151and the fusion splicing apparatus171without any damage of the optical connector ferrule185and the short optical fiber5.

The present invention is explained in detail with reference to the particular embodiments. But it is apparent for those skilled in the art that various variations and modifications can be applied without departing from a spirit and a scope of the present invention.

This application is based upon Japanese Patent Application (Patent Application No. 2006-307142) filed Nov. 13, 2006; the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The holder can protect the optical connector ferrule and the short optical fiber from the impact, etc. from the external cause if the connector plug having the optical connector ferrule is housed therein.

In addition, this holder can position the short optical fiber fitted to the optical connector ferrule in the fusion position of the fusion splicing apparatus. Therefore, the troublesome operation for picking up the connector plug from the holder in the fusion splicing operation can be omitted, and the handling property in the fusion splicing operation can be improved.

Also, the short optical fiber fitted to the optical connector ferrule and other coated optical fiber can be fusion-spliced not to take out the connector plug from the holder. Thus, the operability of the fusion splicing operation can be improved.

Also, when the thermal shrinkage processing portion for causing the thermal shrinkable tube to thermally shrink is provided in parallel with the fusion processing portion, thermal shrinkage process of the thermal shrinkable tube can be executed not to take out the connector plug from the holder.

Further, the optical connector assembling method can assemble the optical connector effectively by using the above holder and the above fusion splicing apparatus without any damage of the optical connector ferrule and the short optical fiber.