Optical connector and optical connector ferrule

An optical connector comprises a housing, a regulating portion which is protrudes toward an inner surface of the housing, a ferrule which is secured to an optical fiber and which is accommodated inside the housing so as to be movable. The ferrule includes a base portion and a thinned portion that has a thickness smaller than that of the base portion. If the ferrule moves forward in the butt-connection direction, the regulating portion and the base portion approach each other, so that the regulating portion regulates the movement of the ferrule in the thickness direction. If the ferrule moves backward in the butt-connection direction, the ferrule reaches a position where the thinned portion faces the regulating portion, so that the movement of the ferrule in the thickness direction is not regulated by the regulating portion.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an optical connector that is assembled to a front end of a light propagating body such as an optical fiber cord or an optical fiber cable, and is relates to an optical connector ferrule that is used to the optical connector.

Description of the Related Art

As an optical connector, for example, there is known a structure in which a guide pin positioning type ferrule is accommodated in a cylindrical housing as in an MPO type optical connector (stipulated in JIS C5982 and the like, MPO: Multi-fiber Push On) (for example, see Japanese Unexamined Patent Application, First Publication No. 2002-196189).

In the optical connector, the movement of the ferrule is generally regulated by the housing in order to reliably fit the guide pin during butt-connection.

For this reason, if the optical connector is largely inclined or the housing is largely bent when the optical fiber is laterally pulled (so-called side-pull) in the state where the optical connector is connected to an optical connector of a counter connection part inside an optical connector adapter, an excessive force is exerted on the ferrule due to the housing, which may cause a problem in that the ferrule may be broken or the state of the butt-connection between the ferrules may be affected.

SUMMARY

The invention is made in view of such circumstances, and it is an object of the invention to provide an optical connector and an optical connector ferrule capable of reliably fitting a guide pin at the time of connection and preventing side-pull adversely affecting a ferrule and a connection state thereof.

An aspect of the invention provides an optical connector which includes a housing; a regulating portion which protrudes toward an inner surface of the housing; a ferrule which is secured to an optical fiber, and which is accommodated inside the housing so as to be movable in a butt-connection direction, wherein the ferrule comprises: a base portion, which has a first thickness extending in a thickness direction that is perpendicular to the butt-connection direction; and a thinned portion, which is formed at a front side of the base portion and has a second thickness that is smaller than the first thickness, wherein if the ferrule moves forward in the butt-connection direction, the regulating portion and the base portion approach each other so that the regulating portion regulates the movement of the ferrule in the thickness direction, and wherein if the ferrule moves backward in the butt-connection direction, the regulating portion and the thinned portion separate from each other so that the movement of the ferrule in the thickness direction is not regulated by the regulating portion.

In the optical connector of the aspect of the invention, a plurality of regulating portions may be provided at upper and lower inner surfaces of the housing.

In the optical connector of the aspect of the invention, the housing may accommodate an inserting optical fiber having an end portion fixed to an end surface of the ferrule at a joint portion, and another end portion connected to the optical fiber, and a joint reinforced portion which reinforces the joint portion.

Another aspect of the invention provides an optical connector ferrule which is secured to an optical fiber in a butt-connection direction, and which is insertable into a housing of an optical connector, the ferrule comprises a base portion having a thickness in a thickness direction that is perpendicular to the butt-connection direction; a thinned portion that is in front of the base portion and has a thickness smaller than the thickness of the base portion, wherein the ferrule is movable in the butt-connection direction; wherein if the ferrule moves forward in the butt-connection direction, the base portion moves toward an inner surface of the housing and movement of the ferrule in the thickness direction is regulated as the base portion approaches the housing, and wherein if the ferrule moves backward in the butt-connection direction, the movement of the ferrule in the thickness direction is released as the thinned portion separates from the housing.

An aspect of the invention provides an optical connector which includes a housing; a regulating portion which serves as a protrusion protruding inward from the inner surface of the front end of the housing; and a ferrule which is secured to an optical fiber, and which is accommodated inside the housing so as to be movable in a butt-connection direction, wherein the ferrule comprises: a body portion with a joint end surface; and a locking convex portion formed at a rear side of the body portion so as to protrude from a side portion of the ferrule; the body portion comprises: a base portion having a side surface on which an opening communicating with an inner portion of the base portion is not provided, the side surface extending along a front-rear direction of the ferrule, the base portion being disposed at a front side of the locking convex portion so as to be adjacent to the locking convex portion, the base portion having a first thickness extending in a thickness direction that is perpendicular to the butt-connection direction, the locking convex portion having a second thickness, and the first thickness of the base portion being smaller than the second thickness of the locking convex portion; and a thinned portion, which is formed adjacently at a front side of the base portion and has a third thickness that is smaller than the first thickness; wherein if the ferrule moves forward in the butt-connection direction, the regulating portion and the base portion approach each other so that the regulating portion regulates the movement of the ferrule in the thickness direction; and wherein if the ferrule moves backward in the butt-connection direction, the regulating portion and the thinned portion separate from each other so that the movement of the ferrule in the thickness direction is not regulated by the regulating portion.

In the optical connector of the aspect of the invention, a plurality of regulating portions may be provided at upper and lower inner surfaces of the housing.

In the optical connector of the aspect of the invention, the housing may accommodate: an inserting optical fiber having an end portion fixed to an end surface of the ferrule at a joint portion and another end portion connected to the optical fiber; and a joint reinforced portion which reinforces the joint portion.

An aspect of the invention provides an optical connector which includes a housing; a regulating portion which serves as a protrusion protruding inward from the inner surface of the front end of the housing; and a ferrule which is secured to an optical fiber, and which is accommodated inside the housing so as to be movable in a butt-connection direction, wherein the ferrule comprises: a body portion with a joint end surface; and a locking convex portion formed at a rear side of the body portion so as to protrude from a side portion of the ferrule; the body portion comprises: a base portion being disposed at a front side of the locking convex portion so as to be adjacent to the locking convex portion, the base portion having a first thickness extending in a thickness direction that is perpendicular to the butt-connection direction, the locking convex portion having a second thickness, the first thickness of the base portion being smaller than the second thickness of the locking convex portion, a thinned portion, which is formed adjacently at a front side of the base portion and has a third thickness that is smaller than the first thickness, and a lens located on an extension line of the optical fiber; wherein if the ferrule moves forward in the butt-connection direction, the regulating portion and the base portion approach each other so that the regulating portion regulates the movement of the ferrule in the thickness direction; and wherein if the ferrule moves backward in the butt-connection direction, the regulating portion and the thinned portion separate from each other so that the movement of the ferrule in the thickness direction is not regulated by the regulating portion.

In the optical connector of the aspect of the invention, a side surface recess may be provided on a side surface of the body portion, the side surface extending along a front rear direction of the ferrule, the side surface recess being opened on the side surface; wherein an inserted optical fiber is fixed to the body portion so that one end portion of the inserted optical fiber is brought into contact with a surface of the side surface recess and so that another end portion of the inserted optical fiber is connected to the optical fiber.

An aspect of the invention provides an optical connector ferrule, which is secured to an optical fiber in a butt-connection direction, and which is insertable into a housing of an optical connector, the ferrule comprises a body portion with a joint end surface; and a locking convex portion formed at a rear side of the body portion so as to protrude from a side portion of the ferrule, the body portion comprising: a base portion having a side surface on which an opening communicating with an inner portion of the base portion is not provided, the side surface extending along a front-rear direction of the ferrule, the base portion being disposed at a front side of the locking convex portion so as to be adjacent to the locking convex portion, the base portion having a first thickness in a thickness direction that is perpendicular to the butt-connection direction, the locking convex portion having a second thickness, the first thickness of the base portion being smaller than the second thickness of the locking convex portion; and a thinned portion that is adjacently in front of the base portion and has a third thickness smaller than the first thickness of the base portion; wherein the ferrule is movable in the butt-connection direction; wherein if the ferrule moves forward in the butt-connection direction, the base portion moves toward an inner surface of the housing and movement of the ferrule in the thickness direction is regulated as the base portion approaches the housing; and wherein if the ferrule moves backward in the butt-connection direction, the movement of the ferrule in the thickness direction is released as the thinned portion separates from the housing.

An aspect of the invention provides an optical connector ferrule, which is secured to an optical fiber in a butt-connection direction, and which is insertable into a housing of an optical connector, the ferrule comprises a body portion with a joint end surface; and a locking convex portion formed at a rear side of the body portion so as to protrude from a side portion of the ferrule, the body portion comprising: a base portion being disposed at a front side of the locking convex portion so as to be adjacent to the locking convex portion, the base portion having a first thickness in a thickness direction that is perpendicular to the butt-connection direction, the locking convex portion having a second thickness, the first thickness of the base portion being smaller than the second thickness of the locking convex portion; a thinned portion that is adjacently in front of the base portion and has a third thickness smaller than the first thickness of the base portion; and a lens located on an extension line of the optical fiber; wherein the ferrule is movable in the butt-connection direction; wherein if the ferrule moves forward in the butt-connection direction, the base portion moves toward an inner surface of the housing and movement of the ferrule in the thickness direction is regulated as the base portion approaches the housing, and wherein if the ferrule moves backward in the butt-connection direction, the movement of the ferrule in the thickness direction is released as the thinned portion separates from the housing.

In the optical connector ferrule of the aspect of the invention, a side surface recess may be provided on a side surface of the body portion, the side surface extending along a front rear direction of the ferrule, the side surface recess being opened on the side surface, wherein an inserted optical fiber is fixed to the body portion so that one end portion of the inserted optical fiber is brought into contact with a surface of the side surface recess and so that another end portion of the inserted optical fiber is connected to the optical fiber.

According to an aspect of the invention, since the ferrule includes the base portion and the thinned portion having a thickness smaller than that of the base portion, the movement of the ferrule in the thickness direction at the base portion is regulated by the regulating portion of the housing in a non-connection state. So that the guide pin can be reliably fitted to the guide pin inserting hole of the counter optical connector during connection work.

Further, when the ferrule is retracted due to the butt-connection, the thinned portion reaches the position facing the regulating portion of the housing, so that the regulation of the movement in the thickness direction is released.

For this reason, even when the optical fiber is laterally pulled (side-pull), an excessive force is not exerted on the ferrule due to the housing, the breakage of the ferrule can be prevented, and the state of the connection with the counter optical connector is not adversely affected.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an exemplary embodiment of the invention will be described by referring to the drawings.

FIGS. 2A and 2Bshow an optical connector10of the embodiment.FIG. 1is a perspective view showing a ferrule12of the optical connector10.FIGS. 3A and 3Bare cross-sectional views showing the ferrule and a joint reinforced portion of the optical connector10. Furthermore,FIGS. 2A and 2Bmay be simply referred to as “FIG. 2”.

The optical connector10has a configuration in which the other end portion (second end portion)43of an inserting optical fiber40having one end portion (first end portion)42fixed to the ferrule12(the optical connector ferrule) is fusion spliced with a front end portion46of an external optical fiber45, and a joint reinforced portion50formed by interposing a fusion splicing portion44between a pair of reinforced members51and54so as to reinforce the fusion splicing portion44is accommodated inside a housing or the like.

In the description below, in order to distinguish both directions along the longitudinal direction of the optical fiber (the left-right direction ofFIG. 2), the direction in which a joint end surface14of the ferrule12faces (the left side ofFIG. 2) may be referred to as a “front end direction” or a “front side”, and the opposite direction (the right side ofFIG. 2) may be referred to as a “rear end direction”, a “base end direction”, or a “rear side”. The front-rear direction indicates the longitudinal direction in one end portion42of the inserting optical fiber40, and also indicates the connection direction when the optical connector10is connected to the optical connector which serves as the counter connection part.

Further,FIGS. 3A and 3Bmay be referred to as “FIG. 3”,FIGS. 6A and 6Bmay be referred to as “FIG. 6”, andFIGS. 11A and 11Bmay be referred to as “FIG. 11”.

The external optical fiber45includes a light propagating body with an optical fiber such as an optical fiber cord or an optical fiber cable. In the case of the embodiment, the external optical fiber45is an optical fiber cord that includes a multi-core optical fiber core47which is formed by an optical fiber ribbon with a plurality of optical fibers (optical fiber strands, not shown) arranged in line in the lateral direction perpendicular to the longitudinal direction, a tubular jacket48which encloses the periphery of the multi-core optical fiber core47, and a tension fiber49which is accommodated between the optical fiber core47and the jacket48. At the front end portion46of the external optical fiber45, a resin coating of the optical fiber core47and a resin coating of the optical fiber strand are removed, so that a plurality of bare optical fibers (the portions of a core and a clad) are separated from each other.

The number of bare optical fibers46(the number of cores) included in the optical fiber core47may be, for example, two cores, four cores, eight cores, twelve cores, or the like. Furthermore, only four cores are shown inFIGS. 2A, 3A, 4, 7, and 10by simplifying the configuration of twelve cores. The optical fiber cord of the embodiment has a configuration in which one optical fiber ribbon is accommodated inside the jacket, but the invention is not particularly limited thereto. For example, the external optical fiber may adopt a configuration in which one jacket accommodates a plurality of single core optical fiber core, one jacket accommodates a plurality of optical fiber ribbons, or one jacket accommodates one or more optical fiber ribbons and one or more single core optical fiber cores.

The jacket48is formed of for example, a resin such as polyethylene and desirably has flexibility. A plurality of the tension fibers49extend along the longitudinal direction of the optical fiber, and function as tension bodies which receive a tensile force (a tension) exerted on the light propagating body. The fiber material used in each tension fiber49is not particularly limited as long as the material is able to obtain a demanded tensile strength, and for example, an aramid fiber, a glass fiber, a carbon fiber, and the like may be exemplified.

Furthermore, the tension body or the jacket is not essentially needed in the invention. For example, an optical fiber core or an optical fiber ribbon without the jacket may be used as the external optical fiber. Further, for example, various wires such as a metallic wire which is a steel wire or a fiber-reinforced plastic (FRP) wire may be used as the tension body depending on the structure of the optical fiber cable or the like. As the optical fiber cable, an optical drop cable, an optical indoor cable, and the like may be exemplified.

The inserting optical fiber40is an optical fiber of which one end portion (first end portion)42is fixed to the ferrule12and the other end portion (second end portion)43protrudes (extends) backward from the ferrule12. In the case of the embodiment, the inserting optical fiber40is formed as a multi-core optical fiber core41formed of an optical fiber ribbon, where at one end portion42and the other end portion43of the optical fiber core wire41, the resin coating of the optical fiber core41and the resin coating of the optical fiber strand are removed so that a plurality of bare optical fibers (the portions of the core and the clad) are separated from each other.

The front end of the inserting optical fiber40is exposed to the joint end surface14, and is butt-connected to the optical fiber of the optical connector corresponding to the counter connection part.

Furthermore, the optical fiber used as the inserting optical fiber40is not limited to the multi-core optical fiber, and a configuration may be adopted in which one or a plurality of short single core optical fibers are inserted into one ferrule, a plurality of optical fiber ribbons are accommodated into one ferrule, or one or more optical fiber ribbons and one or more single core optical fiber cores are accommodated into one ferrule.

As shown inFIG. 4, the other end portion43of the inserting optical fiber40corresponds one-to-one to the front end portion46of the external optical fiber45, and both of them are fusion spliced. Then, as shown inFIG. 3, the fusion splicing portion44of the other end portion43of the inserting optical fiber40and the front end portion46of the external optical fiber45is reinforced by being interposed between the pair of reinforced members51and54at the joint reinforced portion50.

The reinforced members51and54respectively include reinforced member bodies52and55which are formed as rigid members such as resin or metal, and adhesion layers53and56which are provided at the inner surface side corresponding to the side contacts to the other end portion43of the inserting optical fiber40and the front end portion46of the external optical fiber45.

As shown inFIGS. 5 to 7, the pair of reinforced members51and54respectively includes a convex portion61and a concave portion62which engage with each other at both sides of the width direction (the direction perpendicular to the plane of paper ofFIG. 5) corresponding to the direction perpendicular to the longitudinal direction of the inserting optical fiber40and the external optical fiber45. By engaging the convex portion (the engagement convex portion)61with the concave portion (the engagement concave portion)62, the adhesion state between the adhesion layers53and56of the pair of reinforced members51and54is maintained.

The body55of the second reinforced member54includes a bottom wall portion57and side wall portions58and58provided at both sides in the width direction, and the engagement concave portion62is a penetration hole formed at the side wall portion58.

The side wall portion58of the second reinforced member54is divided into a plurality of portions (tongue-shaped portions) with notched portions59interposed therebetween, and one or less engagement concave portions62is formed at one piece of the side wall portion58.

In order to easily open and close the reinforced members51and54, a slope58ais formed at the inner surface of the side wall portion58.

The adhesion layers53and56respectively include bulged portions53aand56aof which the surface heights are bulged near the fusion splicing portion44, so that a further high pressing force can be maintained between the bulged portions53aand56a. Further, both sides of the bulged portions53aand56a(both sides of the bare optical fibers43and46in the longitudinal direction) are provided with alleviation portions53band56bof which the surface heights are lower than that of the bulged portions53aand56a, so that the pressing force is alleviated.

As shown inFIG. 7, the adhesion layers53and56are depressed at a position contacts to the inserting optical fiber and the external optical fiber (which are generally shown as the optical fiber F inFIG. 7) so as to come into close contact with the outer peripheral surface of the optical fiber F in the vicinity of the fusion splicing portion44.

As shown inFIGS. 1 to 3, the ferrule12includes a front end surface (a joint end surface)14which is butt-connected to a ferrule (not shown) of another optical connector (an optical connector corresponding to a counter connection part), a rear end surface16which is an end surface opposite to the joint end surface14, an optical fiber inserting hole (a microscopic hole)13which is opened to the joint end surface14, and a boot accommodating hole17which is opened to the rear end surface16. The ferrule12can be manufactured as, for example, a plastic single molding product. The joint end surface14of the ferrule12may be a perpendicular surface which is perpendicular to the center axis of the optical fiber inserting hole13(which approximately matches the optical axis of the optical fiber42) or a slope which is inclined in a predetermined direction corresponding to the ferrule of another optical connector.

The optical fiber inserting hole13is formed as many as the number of the optical fibers at one end portion42of the inserting optical fiber40. As a method of fixing the bare optical fiber corresponding to one end portion42of the inserting optical fiber40to the ferrule12, for example, a method of injecting adhesive into the optical fiber inserting hole13is simple. Each of the optical fiber inserting holes13is connected to the boot accommodating hole17. A ferrule boot18is attached to the periphery of the optical fiber core41, and is accommodated in the boot accommodating hole17. It is desirable that the ferrule boot18be formed of, for example, a material such as rubber or elastomer with flexibility. However, the ferrule boot18may be formed of a material such as resin or metal with low flexibility.

The number of the optical fiber inserting holes13provided in the ferrule12(the number of cores) may be, for example, two cores, four cores, eight cores, twelve cores, and the like, and the optical fiber inserting holes13are provided in accordance with the number of cores of the optical fiber core47. Furthermore, in the optical connector10of the embodiment, a single core ferrule may be used as the ferrule12.

Regarding the arrangement of the optical fiber inserting holes13at the joint end surface14of the multi-core ferrule12, it is desirable that the optical fiber inserting holes13be arranged in line in accordance with the arrangement of the optical fibers interposed between the reinforced members51and54. Furthermore, the invention is not limited to a configuration in which the arrangement of the optical fibers in the ferrule12is the same as the arrangement of the optical fibers in the joint reinforced portion50, but the arrangement of the optical fibers separated for each core between the ferrule12and the joint reinforced portion50may be changed.

As shown inFIGS. 1 and 11A, the ferrule12includes a body portion101with the joint end surface14and a locking convex portion102formed at the rear side of the body portion101so as to protrude outward.

The ferrule12is formed in a shape in which the dimension in the arrangement direction of the optical fiber inserting holes13(the up-down direction ofFIG. 2A) is larger than the dimension in the direction perpendicular thereto (the up-down direction ofFIG. 2B), that is, a flat shape. Hereinafter, the arrangement direction of the optical fiber inserting holes13is set as the width direction, and the direction perpendicular thereto is set as the thickness direction.

The joint end surface14of the ferrule12is substantially formed in a rectangular shape of which the side along the width direction is set as the long side and the side along the thickness direction is set as the short side.

InFIGS. 2B, 3B, 11B, and the like, the left direction indicates a direction in which the ferrule12is butt-connected to the counter connection optical connector110(the counter optical connector110), and the up-down direction perpendicular thereto indicates the thickness direction of the ferrule12.

As shown inFIG. 2, the ferrule12is movable in the front-rear direction (the butt-connection direction) while being biased forward by a ferrule spring24.

For this reason, as shown inFIG. 11A, the ferrule12is comparatively positioned at a front side while the optical connector10is not connected to the counter connection optical connector110(the counter optical connector110) (in a non-connection state). However, as shown inFIG. 11B, when the optical connector10is butt-connected to a ferrule112of the counter optical connector110, the ferrule12is pressed by the ferrule112so as to move backward.

Hereinafter, the position of the ferrule12shown inFIG. 11Aindicates an “advanced position”, and the position of the ferrule12retracted due to the butt-connection as shown inFIG. 11Bindicates a “retracted position”.

As shown inFIG. 1, the locking convex portion102is formed from both surfaces of the body portion101in the thickness direction (an upper surface101aand a lower surface101b) and both side surfaces101cand101c.

As shown inFIG. 2A, the forward movement of the locking convex portion102is regulated by a locking protrusion22aformed in the inner surface of the plug frame21, whereby the forward movement of the ferrule12is regulated and the separation of the ferrule12is prevented.

As shown inFIG. 2BandFIG. 11A, the inner surfaces (the ceiling surface and the bottom surface) of the plug frame21(housing11) are respectively provided with regulating portions22band22cwhich regulate the movement of the ferrule12in the thickness direction.

The shape and the formation position of the regulating portions22band22care not limited as long as the regulating portion can regulate the movement of the ferrule12in the thickness direction in the non-connection state. However, it is desirable that the regulating portions be formed as a protrusion protruding inward from the inner surface of the front end of the plug frame21.

Furthermore, the regulating portion may be formed only at one of the inner surfaces (the ceiling surface and the bottom surface) of the plug frame21in the thickness direction. However, it is desirable that the regulating portions be formed at both inner surfaces as shown in the drawings in that the movement toward both sides in the up-down direction is regulated.

As shown inFIG. 1, the body portion101includes a base portion103and a thinned portion104which is provided at the front side of the base portion103so as to be thinner than the thickness of the base portion103.

The base portion103is formed so as to have a substantially rectangular shape, and is formed so as to have substantially the same thickness in the front-rear direction.

The thickness of the base portion103is set so that the movement of the ferrule12in the thickness direction is regulated by the regulating portions22band22cwhen the ferrule12is positioned at the advanced position.

That is, as shown inFIG. 11A, the thickness h of the base portion103is set so that the front ends (the protruding ends) of the regulating portions22band22capproach the outer surfaces (the upper surface and the lower surface) of the base portion103facing the front ends, and the movement of the ferrule12in the up-down direction hardly occurs or the movement amount is extremely small even when the ferrule12moves in the up-down direction.

Furthermore, in the example shown in the drawing, the regulating portions22band22care not used to prohibit the movement of the ferrule12in the front-rear direction.

As shown inFIGS. 1 and 11A, the thinned portion104is formed so as to have a substantially cross-sectional rectangular shape, and is formed so as to have substantially the same thickness in the front-rear direction.

As shown inFIG. 11A, the thinned portion104is formed by a thinned concave portion104awhich is formed at the front end side portion of the body portion101.

It is desirable that the thinned concave portion104abe formed at both surfaces of the body portion101in the thickness direction, that is, the upper surface101aand the lower surface101bof the body portion101. With such a configuration, when the ferrule12is retracted due to the butt-connection, the ferrule12is movable in both directions (the up direction and the down direction) in the thickness direction, whereby the position adjusting function can improve.

Furthermore, the thinned concave portion104amay be formed only at one surface of the body portion101in the thickness direction.

The thickness of the thinned portion104is set so that the regulation of the movement using the regulating portions22band22cis released when the ferrule12is positioned at a position retracted (the retracted position) due to the butt-connection with the counter optical connector110.

Specifically, as shown inFIG. 11B, the thickness k of the thinned portion104is set so that the movement of the ferrule12in the up-down direction is permitted due to a sufficient gap between the front ends (the protruding ends) of the regulating portions22band22cand the outer surfaces (the upper surface and the lower surface) of the thinned portion104facing the front ends at the retracted position.

As shown inFIG. 3B, the ferrule boot18is attached to the ferrule12so as to coat the periphery of the portion of the inserting optical fiber40protruding from the ferrule12. The pair of reinforced members51and54(specifically, the bodies52and55) include protrusions which are provided at an end of the reinforced member near the ferrule12and serve as boot gripping portions52aand55a, and grips the ferrule boot18between the boot gripping portions52aand55a.

Accordingly, both ends of the ferrule boot18are properly held between the ferrule12and the pair of reinforced members51and54, so that the bending or the damage of the inserting optical fiber40can be more reliably prevented.

Further, since the slight bending of the ferrule boot18is permitted, even when a force in the bending direction is applied to the joint reinforced portion50due to the side-pull, the damage of the ferrule12and the joint reinforced portion50can be prevented.

Since the joint reinforced portion50is connected to the rear side of the ferrule12through the ferrule boot18, these are generally referred to as a “joint reinforced portion attached ferrule100”.

The ferrule12is provided with guide pins15of which the front ends protrude forward from the joint end surface14so as to position the ferrule with respect to the counter connection optical connector.

The guide pins15are provided so as to be inserted through guide pin inserting holes15apenetrating between the joint end surface14and the rear end surface16. When the guide pins15are inserted into guide pin inserting holes (not shown) provided in a ferrule of another optical connector, the positional deviation in the direction along the surface of the joint end surface14(the up-down direction ofFIG. 3A, the up-down direction ofFIG. 3B, or the inclined direction obtained by the combination thereof) is suppressed, and the accurate positioning operation between the optical connector10and the counter connection optical connector can be performed.

The type with which the positioning operation with respect to the counter connection optical connector is performed using the guide pins15is called a guide pin positioning type.

As shown inFIG. 3A, in the example shown in the drawing, the guide pin inserting holes15aand15aare used to allow the guide pins15to be freely inserted thereinto and extracted therefrom, where the guide pin inserting holes are provided along the front-rear direction, and are respectively provided at one side and the other side of the optical fiber inserting hole13, through which the inserting optical fiber40is inserted, namely the optical fiber inserting hole13are interposed between the guide pin inserting holes15aand15a.

The guide pins15are provided so as to be respectively inserted through the pair of guide pin inserting holes15a.

As shown inFIGS. 1 and 8, the guide pin15is substantially formed in a cylindrical shape, and includes a body portion90which has a taper-shaped front end portion90a, and a base end portion91which is formed at the rear end side of the body portion90.

The base end portion91includes a neck portion92which extends backward from the rear end of the body portion90and a head portion93which is provided at the rear end of the neck portion92. The neck portion92is formed so as to be smaller in diameter than the head portion93, and the body portion90is formed so as to be larger in diameter than the neck portion92.

As shown inFIGS. 1 to 3, the body portion90is inserted through the guide pin inserting hole15a, and protrudes forward from the joint end surface14.

Furthermore, the optical connector10shown inFIGS. 1 to 3may be formed as a type (a male type) with the guide pin15, but as described below, the optical connector may be formed as a type (a female type) without the guide pin15.

As shown inFIGS. 1 to 3, the rear end surface16of the ferrule12is provided with a pin clamp19. The position of the pin clamp19in the front-rear direction is present at the front side of the fusion splicing portion44.

As shown inFIG. 8, the pin clamp19is used to support the guide pin15, and is attachably and detachably attached to the base end portion91of the guide pin15.

The pin clamp19of the example shown in the drawing is formed of a synthetic resin material or the like, and is formed in a substantial U-shape which has a bottom portion71and side wall portions72and72provided at both side portions of the bottom portion71.

The side wall portions72and72are formed so as to be separated from each other with an insertion space73interposed therebetween, and the inserting optical fiber40is inserted through the insertion space73(seeFIGS. 2 and 3). The insertion space73may be formed so that the ferrule boot18is fittable thereinto.

The side wall portions72and72are respectively provided with fitting concave portions83and83. The base end portion91(the neck portion92) of the guide pin15may be fitted to the fitting concave portion83from a direction substantially perpendicular to the guide pin inserting hole15a.

As shown inFIGS. 8 to 10, a positioning convex portion81protruded backward is provided at the rear surface of the side wall portion72.

The positioning convex portion81is used to prevent the positional deviation of the ferrule spring24, and is inserted into the front end portion of the ferrule spring24(seeFIG. 2).

The rear surface of the side wall portion72becomes a spring seat20which receives a biasing force (a pressing force caused by elasticity) from the ferrule spring24. For this reason, even when the ferrule12is not provided with the guide pin15, the pin clamp19is attached to the ferrule12. The pin clamp19can be fitted and fixed to the ferrule12through, for example, a concave or a convex (not shown) or the like.

As shown inFIGS. 9 and 10, a notch84is formed at the center portion of the rear edge of the bottom portion71so as to have a size which permits the upward and downward movement of the boot gripping portion55aformed at the body55of the reinforced member54.

The optical connector10described in the embodiment is a multi-core optical connector, and may have the same structure as that of the MPO type optical connector (an F13-type multi-core optical fiber connector stipulated in JIS C 5982; MPO: Multi-fiber Push On). The optical connector applicable to the invention is not particularly limited regardless of whether it is for a single core or multiple cores.

The housing11of the optical connector10includes the sleeve-shaped (cylindrical) plug frame21and a sleeve-shaped (cylindrical) stop ring30which is attached to the rear end side of the plug frame21.

The ferrule12is inserted through the front end side opening22of the plug frame21.

An engagement claw33, which can engage with an engagement window27formed at the side wall portion of the plug frame21, is formed at the outer surface of the stop ring30so as to integrate the plug frame21and the stop ring30with each other.

The ferrule spring24(the biasing member) is used to bias the ferrule12forward through the pin clamp19, and is disposed around the joint reinforced portion50so as to allow the front end side of the spring24to come into contact with the spring seat20at the rear end side of the pin clamp19and allow the rear end side of the spring24to come into contact with the spring seat31at the front end side of the stop ring30.

When the joint end surface14of the ferrule12is connected to a ferrule of another optical connector, the ferrule12is pressed backward while being guided inside the opening22, so that the ferrule spring24contracts. Then, an appropriate pressing force is exerted between the joint end surface14of the ferrule12and the joint end surface of the ferrule of another optical connector, so that the joint end surfaces come into close contact with each other. Further, when the connection between the ferrule12and the ferrule of another optical connector is released, the ferrule spring24expands, so that the ferrule12moves inside the opening22and returns to the original position.

Engagement portions23are provided at both sides of the plug frame21in the width direction (both upper and lower sides ofFIG. 2A) so as to allow an MPO type connector plug to engage with an MPO type connector adapter or an engagement claw (not shown) of a receptacle. Further, the outer periphery of the plug frame21is provided with a coupling25, and a pair of coupling springs26and26is accommodated between the outer peripheral surface of the plug frame21and the inner peripheral surface of the coupling25. Accordingly, the coupling25can move forward and backward relative to the plug frame21in accordance with the expanding or the contracting of the coupling springs26and26. The engagement portion23or the coupling25corresponds to the MPO type optical connector plug, and has the same configuration as that stipulated in the above-described JIS or the like.

Furthermore, in the case where the invention is applied to a different type of optical connector, a configuration necessary for the connection of the optical connector (the connector connection) is appropriately provided at the ferrule, the housing or the like.

A penetration hole32is formed inside the stop ring30, in which the penetration hole32penetrate in the front-rear direction (the left-right direction ofFIG. 2) along the longitudinal direction of the optical fiber. The cross-sectional shape of the penetration hole32(the cross-sectional shape in the plane perpendicular to the longitudinal direction of the optical fiber) at least includes the cross-sectional shape of the joint reinforced portion50. Accordingly, when the stop ring30is press-inserted into the plug frame21from the rear side of the joint reinforced portion50while the ferrule12is inserted into the opening22of the plug frame21, the stop ring30does not interfere with the joint reinforced portion50(the press-inserting is not disturbed). When the stop ring30is press-inserted into the plug frame21from the rear side of the joint reinforced portion50, the engagement claw33is pulled into the joint reinforced portion50immediately before the engagement claw33reaches the engagement window27. For this reason, a groove32ais provided in the inner surface of the penetration hole32at the rear surface side of the engagement claw33, so that the interference between the rear surface of the engagement claw33and the joint reinforced portion50is prevented.

A male screw portion34is formed at the outer peripheral surface of the rear end of the stop ring30. The male screw portion34is fastened to the female screw portion36formed at the inner peripheral surface of the screw ring35. The front end portion of the tension fiber49of the external optical fiber45can be interposed and fixed between the male screw portion34and the female screw portion36. The screw ring35includes an opening37at the rear end side thereof, and the portions of the tension fiber49of the external optical fiber45and the optical fiber core wire47are inserted through the opening37. It is desirable that the cross-sectional shape of the opening37(the cross-sectional shape in a plane perpendicular to the longitudinal direction of the optical fiber) have a certain degree of opening dimension so as to prevent the tension fiber49and the joint reinforced portion50from coming into contact with each other.

The outer peripheral surface of the screw ring35is provided with an external optical fiber boot65which is used to protect the external optical fiber45. The external optical fiber boot65is generally formed of a material with flexibility such as rubber or elastomer or the like. In the case of the embodiment, a protection tube66is attached to the periphery of the jacket48of the external optical fiber45, and an annular fitting portion67of which the diameter increases at the front end side of the tube66is fitted into the external optical fiber boot65.

The sequence of assembling the housing or the like is not particularly limited, but for example, the following sequence may be exemplified.

As an advance preparation performed before fusion splice, the external optical fiber45is made to pass through the ferrule spring24, the stop ring30, the screw ring35, the external optical fiber boot65, and the protection tube66. It is desirable that these components be disposed at the rear side (the right side ofFIG. 2) so as not to disturb the fusion splice.

The bare optical fibers43and46are fusion spliced, and the fusion splicing portion44is reinforced by being interposed between the pair of reinforced members51and54at the joint reinforced portion50.

As shown inFIG. 8, since the fitting concave portion83of the pin clamp19is formed downward, the neck portion92of the guide pin15can be inserted or extracted in the up-down direction.

For this reason, when the pin clamp19is moved laterally (from the downside to the upside inFIG. 8) so that the base end portion91of the guide pin15is fitted to the fitting concave portion83, the pin clamp19can be installed at the rear end side of the ferrule12.

After the ferrule12is disposed inside the opening22of the plug frame21by attaching the plug frame21from the front side of the ferrule12(the left side ofFIG. 2), the stop ring30is press-inserted into the plug frame21so as to allow the engagement claw33to engage with the engagement window27and accommodate the ferrule spring24together with the ferrule12and the joint reinforced portion50. The coupling25may be attached onto the plug frame21in advance or may be attached thereto after the attachment of the stop ring30.

The front end portion of the tension fiber49is disposed on the male screw portion34of the stop ring30, and the female screw portion36of the screw ring35is fastened to the male screw portion34so as to fix the front end portion of the tension fiber49. When the front end portion of the tension fiber49extends to the outer periphery of the plug frame21, the front end portion is cut if necessary. Furthermore, the boot65is attached onto the stop ring30. According to the above-described sequence, the optical connector10shown inFIG. 2can be assembled.

Furthermore, when the external optical fiber does not include the tension fiber, the housing may be integrated by fastening the female screw portion36of the screw ring35to the male screw portion34of the stop ring30without interposing the tension fiber.

The optical connector10shown inFIG. 1is formed as a type (a male type) with the guide pin15. However, a type (a female type) may be adopted by removing the pin clamp19and extracting the guide pin15toward the front end.

Next, the operation of the optical connector10will be described by referring toFIGS. 11 and 12.

As shown inFIG. 11A, in the optical connector10in the non-connection state, the ferrule12is present at the front position. In this state, the regulating portions22band22cof the plug frame21(the housing11) are present at a position facing the base portion103.

Since the base portion103is formed so that the movement thereof in the thickness direction is regulated by the regulating portions22band22c, at the time of connecting the optical connector10to the counter optical connector, the positional deviation of the ferrule12in the up-down direction does not occur, the guide pin15can be reliably fitted to a guide pin inserting hole (not shown) of the counter optical connector, and the connection work is not disturbed.

As shown inFIG. 11B, in the state where the optical connector10is butt-connected to the ferrule112of the counter optical connector110, the ferrule12moves backward while being pressed by the ferrule112, and the thinned portion104reaches a position facing the regulating portions22band22c.

Since the thickness of the thinned portion104is smaller than that of the base portion103, the distance from the regulating portions22band22bincreases, the regulation of the movement using the regulating portions22band22cin the thickness direction is released, so that the ferrule12is permitted to slightly move up and down.

As shown inFIG. 12, when the external optical fiber45is pulled laterally (a so-called side-pull; a direction intersecting the direction of the optical fiber) in the state where the optical connector10is butt-connected to the ferrule112of the counter optical connector110, the force in such a direction may be exerted on the joint reinforced portion attached ferrule100.

In the example shown in the drawing, when a force is exerted on the external optical fiber45downward (in the thickness direction), there is a concern in that the downward force may be exerted on the rear end portion of the joint reinforced portion attached ferrule100.

In the optical connector10, since the slight upward and downward movement of the ferrule12is permitted in the butt-connection state, an excessive force is not exerted on the ferrule12due to the housing11even when the joint reinforced portion attached ferrule100is inclined downward.

Since the excessive force is not exerted on the ferrule12, the damage of the ferrule12can be prevented and the state of the connection with the counter optical connector110is not adversely affected.

The optical connector10shown inFIG. 2uses the inserting optical fiber40fixed to the ferrule12, but the invention is not limited thereto. The external optical fiber may be directly introduced into the ferrule.

FIGS. 13A and 13Bschematically illustrate the optical connector with such a structure, where the optical fiber46drawn from the external optical fiber45is directly introduced into the ferrule12. Furthermore, the description of the configuration which has been already mentioned will not be repeated by giving the same reference numerals thereto.

Further, the optical connector10shown inFIG. 2has a configuration in which the fusion splicing portion44of the inserting optical fiber40and the external optical fiber45is interposed between the pair of reinforced members51and54at the joint reinforced portion50, but the invention is not limited thereto. The fusion splicing portion44may be reinforced by the known reinforced sleeve.

Further, in the connection between the inserting optical fiber40and the external optical fiber45, another connection type, for example, a type (a mechanical splice type) in which the optical fibers are butt-connected between the pair of elements may be adopted.

As shown inFIG. 11and the like, in the optical connector10, the locking convex portion102is provided near the rear end of the ferrule12, but the shape of the locking convex portion is not limited thereto.

FIG. 14shows a modified example of the locking convex portion of the ferrule12. Regarding a locking convex portion102A shown herein, the front end position is the same as that of the locking convex portion102shown inFIG. 11and the like. However, since the rear end of the locking convex portion102A is not near the rear end of the ferrule12, the locking convex portion102A is different from the locking convex portion102in that the dimension in the front-rear direction is small.

The locking convex portion102A has a function of stabilizing the position of the ferrule12present at the advanced position as in the locking convex portion102.

Modified Example of Ferrule

Next, a ferrule212of a modified example which is applicable to the optical connector10according to the first embodiment will be described. The ferrule212of the modified example is different from the above-described ferrule12in that the ferrule212includes a lens206. Identical reference numerals are used for the elements which are identical to those of the first embodiment, and the explanations thereof are omitted or simplified here.

FIG. 15is a perspective view showing the ferrule212.FIG. 16is a cross-sectional view partially showing the ferrule212into which the inserted optical fiber40is to be inserted.

The ferrule212is formed of a transparent member. The ferrule212is a single member made of a resin material. As a resin material used to form the ferrule212, polyetherimide, polycarbonate, cyclic olefin copolymer, cyclic olefin polymer, or other transparent polymers may be adopted. Part of the ferrule212which serves as an optical path from the inserted optical fiber40to the lens206may be only formed of a transparent member.

As shown inFIG. 15, the ferrule212includes a body portion301and a locking convex portion302.

The body portion301includes a front end surface (a joint end surface)214and a side surface212cextending along with a front rear direction of the ferrule212. Furthermore, the body portion301includes a base portion303and a thinned portion304which is provided at the front side of the base portion303so as to be thinner than the thickness of the base portion303.

A locking convex portion302is formed at the rear side of the body portion301so as to protrude outward. The locking convex portion302includes a rear end surface216which is opposite to the front end surface214.

A boot housing hole (not shown in the figure) is provided on the rear-end face216of the ferrule212. The boot housing hole is configured to accommodate the ferrule boot18(refer toFIG. 1B) therein. An optical fiber insertion hole213(micro hole) is opened on the rear-end face216. As shown inFIG. 16, one end portion42of the inserted optical fiber40is inserted into the optical fiber insertion hole213. The inserted optical fiber40is fixed to the optical fiber insertion hole213by, for example, an adhesive.

A side surface recess207is provided on the side surface212cof the ferrule212. The side surface recess207is opened on the side surface212c. The side surface recess207is communicated with the optical fiber insertion hole213. The side surface recess207is formed in a rectangular shape in a plan view. An optical fiber stop plane207athat faces rearward is formed in the side surface recess207. The optical fiber stop plane207ais positioned between the inserted optical fiber40and the lens206. The front end of one end portion42of the inserted optical fiber40is brought into contact with the optical fiber stop plane207a.

As shown inFIG. 16, the side surface recess207is filled with a refractive index matching material208. Consequently, it is possible to control a refractive index in the optical path of light emitted from the front end of the inserted optical fiber40. By use of, for example, a refractive index matching epoxy resin as the refractive index matching material208, it is possible to fix the optical fiber inside the side surface recess207. As a result, it is possible to prevent the front-end position of the inserted optical fiber40from being displaced during use.

A recess205is provided on the front-end face214of the ferrule212. The recess205is depressed with respect to the front-end face214. A plurality of lenses206are formed on the surface205athat faces forward of the recess205. The lenses206are accommodated in the recess205and do not protrude forward from the front-end face214. The lenses206are located on the extension lines L of the inserted optical fibers40. The lenses206are arranged to be optically aligned with corresponding optical fiber insertion holes (optical alignment).

The lenses206are molded integrally in one body which serves as part of the ferrule212. The lenses206collimate light emitted from the front ends of the inserted optical fibers40. The lenses206condense, on the front end of the inserted optical fiber40, light emitted from the other ferrule that is butt-jointed to the ferrule212. It is preferable that the focal point of the lens206be located on the optical fiber stop plane207a.

Even in the case of using the ferrule212of the modified example in the optical connector10according to the first embodiment, the same effect can be obtained.