Abstract:
A universal optical connector adapter that can be used to connect optical connector plugs of the same or different types having ferrules fixed at ends of optical fibers. The universal adapter has first and second housings each having at one end a coupling portion for detachably coupling with an optical connector plug of a given type and on an opposite end a base plate having a reference plane. A cylindrical coupling member is rotatably held inward of the coupling portion of the first housing and incorporates a sleeve for fitting ferrules into opposite sides thereof. A male thread is provided on an outer periphery of the coupling cylindrical member and a female thread is provided in the coupling portion of the second housing on a side opposite to that in which an optical connector plug is coupled. The female thread is removably couplable with the male thread. The first and second housings can be coupled together so that the reference planes are closely contacted and the male thread and female thread are removable.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a universal adapter for optically connecting between optical connector plugs provided at ends of optical fiber cables. 
     Conventionally, the optical connector has been used to optically connect between optical fiber cables. This type of connector is structured by an optical connector plug holding a ferrule fixed at an end of an optical fiber and an optical fiber adapter for optically connecting between the opposed plugs. 
     Meanwhile, there are a plurality of types of optical connectors like this, and they are separately used depending on the application. In order to connect between different plugs, there are prepared conversion adapters. 
     However, there is a problem in that, if there are a plurality of kinds of optical connectors, a plurality of kinds of conversion adapters are required to be prepared. That is, where using optical connectors of all FC type, an SC type and an ST type, for adapters and conversion adapters there is a necessity to prepare six kinds of adapters, resulting in a of very uneconomical procedure. 
     Also, in the manufacture of the apparatuses, there is a problem in that an adapter must be assembled after confirming the kind of optical connector being used. 
     Therefore, it is an object of the present invention to provide a universal adapter that can connect between the different types of optical connector plugs used. 
     SUMMARY OF THE INVENTION 
     A first respect of the invention for solving the above problem resides in providing a universal optical adapter for optical detachably connecting between optical connector plugs having ferrules fixing ends of optical fibers, the universal adapter comprising: first and second receptacle housings each having at one end a coupling portion as a cylinder in a form to decouplably couple with a desired optical connector plug and on the other end a reference plane; a coupling cylindrical member rotatably held inward of the coupling portion of the first receptacle housing and incorporating a sleeve for fitting ferrules from an opposite side; a male thread portion provided in an outer periphery of the coupling cylindrical member; a female thread portion provided in the coupling portion of the second receptacle housing on an opposite side to a coupling end with the optical connector plug and couplable with the male thread portion; wherein the first and second receptacle housings can be coupled in a state that the reference planes are closely contacted in a manner such that the male thread portion and the female thread portion are removable. 
     A second aspect of the invention resides in the universal adapter of the first aspect, wherein the coupling portions of the first and second receptacle housings are couplable with of optical connector plugs of an FC type, an SC type and an ST type. 
     A third aspect of the invention resides in the universal adapter of the first or second aspect, wherein a rotation groove engageable with a jig for rotating the coupling cylindrical member is formed in an end face on an opposite side to the coupling portion of the coupling cylindrical member. 
     A fourth form of the invention lies in the universal adapter wherein, in any of the first to third aspects, an engaging convex protrusion is provided on one of the reference planes of the first and second receptacle housings while a engaging concave portion for engagement with the engaging protrusion is provided on one of the reference planes of the first and second receptacle housings. 
     A fifth aspect of the invention lies in the universal adapter wherein, in the fourth aspect, the engaging convex portion and the engaging concave portion are provided in two sets to restrict movement in a direction along the reference plane and rotation in a plane along the reference plane. 
     A sixth aspect of the invention lies in the universal adapter wherein, in any of the first to fifth aspects, and wherein the second receptacle housing can be fixed to a member to be fixed in a state the reference plane is exposed, the first receptacle housing can be decouplably coupled to the fixed second receptacle housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a universal adapter according to a first embodiment of the invention; 
     FIG. 2 is an assembly sectional view of a universal adapter according to the first embodiment of the invention; 
     FIG. 3 is a rear view of a FC type receptacle housing in the first embodiment of the invention; 
     FIG. 4 is a sectional view of a FC type receptacle in the one embodiment of the invention; 
     FIGS. 5A and 5B are views showing an operation state of the universal adapter according to the first embodiment of the invention; 
     FIGS. 6A and 6B are sectional views of a universal adapter according to a second embodiment of the invention; and 
     FIGS. 7A and 7B are sectional views of a universal adapter according to a third embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Next, an embodiment of an optical connector adapter according to the present invention will be explained based on the drawings. FIG. 1 to FIG. 7 exemplifies a universal adapter according to one embodiment of the invention. 
     The universal adapter  1 A shown in FIG. 1 was assembled as an adapter for an FC-FC connection, and is assembled by an FC type receptacle housing  10  and an FC type receptacle  20  as shown in FIG.  2 . 
     The FC type receptacle housing  10  has, as shown in FIG. 3, a coupling portion  13  formed by a cylinder in a form to be coupled with an FC type optical connector plug, on an opposite side of a reference plane  11  of a base plate  12  having one end surface serving as the reference plane  11 . The coupling portion  13  has a male thread portion  13   a  on an outer peripheral surface and a cut-out  13   b  for engagement with a key ring of the optical connector plug. Furthermore, a step portion  13   c  is provided in an inner peripheral surface. 
     A female thread portion  14  is provided in the inner surface of the coupling portion  13  on the reference plane  11  side. Also, on the reference surface side  11  of the base plate  12 , a reference concave portion  15  is provided that is as a circular concave portion greater in diameter than the female thread portion  14 . Furthermore, on the reference plane  11  side of the base plate  12 , a reference pin  16  is provided protruding from the base plate  12  in the opposite direction from the coupling portion  13 , and a pair of fixing through-holes  17  are provided. Incidentally, a taper formed concave portion  18  is provided at a peripheral edge portion on the reference plane  11  side of the fixing through-holes  17  such that a fixing screw can be accommodated therein. 
     Meanwhile, the FC type receptacle  20  is formed by an FC type receptacle housing  30  and a coupling cylindrical member  40 . 
     The FC type receptacle housing  30  has generally the same shape as the FC type receptacle housing  10 . That is, on an opposite side to a reference plane  31  of a base plate  32  having the reference plane  31  on one side, a coupling portion  33  is provided that is shaped like a cylinder with a form capable of coupling with the FC type optical connector plug. The coupling portion  33  is the same as the FC type receptacle housing  10  in that it has a male thread portion  33   a,  a cut-out  33   b  and a step portion  33   c.  Meanwhile, there is difference in that on the reference plane  31  side of the coupling portion  33 , a small diameter portion  34  is provided, and in the reference plane  31  a ring formed reference convex portion  35  is provided to engage the reference concave portion  15  provided in the reference plane  11  of the FC type receptacle housing  10  and the base plate  32  is provided with a reference hole  36  to fit with the reference pin  16 . 
     Meanwhile, the coupling cylindrical member  40  has a press-fitted pair comprising a first cylindrical member  41  and a second cylindrical member  42  and incorporates inside an optical connecting sleeve  50  such as a split sleeve. That is, the first cylindrical member  41  has an inner diameter size capable of incorporating the optical connecting sleeve  50  in a free-fitting state. On one end side, an optical coupling opening portion  43  is provided that has an inner diameter size greater than the inner diameter size of the optical connecting sleeve  50  although somewhat smaller in diameter than the outer diameter size thereof. Also, on an outer peripheral surface, a male thread portion  44  is provided to be coupled to the female thread portion  14  of the FC type receptacle housing  10 . Also, the second cylindrical member  42  has a fitting portion  45  having an inner diameter size to be fitted with the first cylindrical member  41 , and has on one end side an optical coupling opening portion  46  with generally the same size as the optical coupling opening portion  43  and on the outer peripheral surface a flange portion  47  having a greater diameter than the inner diameter of the step portion  33   c.  Furthermore, a pair of engaging grooves  48  are provided in diametrically opposite positions in a peripheral edge portion of the optical coupling opening portion  46 . Incidentally, the first cylindrical member  41  and the second cylindrical member  42  have end shapes on sides of the optical coupling opening portions  43  and  46  which can couple with the optical connector plug. 
     If the first cylindrical member  41  and the second cylindrical member  42  thus formed are press-fitted in a state incorporating the optical connecting sleeve  50  and the first cylindrical member  41  is inserted in the small diameter portion  34  of the FC type receptacle housing  30 , because the male thread portion  44  is greater in diameter than the small diameter portion  34  and the flange portion  47  is greater in diameter than the step portion  33   c,  the coupling cylindrical member  40  is rotatably engaged with and held by the FC type receptacle housing  30 . 
     The FC type receptacle  20  rotatably engaged and held with the coupling cylindrical member  40  in this manner, as shown in FIG. 2, becomes an adapter  1 A for FC-FC coupling of FIG. 1 by being coupled and assembled with the FC type receptacle housing  10 . 
     This assembling is made by coupling the male thread portion  44  of the coupling cylindrical member  40  to the female thread portion  14  of the FC type receptacle housing  10  such that the reference concave portion  15  and reference pin  16  of the FC type receptacle housing  10  are respectively engaged with the reference convex portion  35  and reference hole  36  of the FC receptacle housing  30 . 
     Incidentally, although this coupling can be made by engaging a minus driver with the pair of engaging grooves  48  provided at the end of the second cylindrical member  42 , an exclusive jig  60  as shown in FIG. 5 may be used. This jig  60 , as shown in FIG. 5A, has at an end a convex portion  62  that can be inserted in the optical coupling opening portion  46 , and on an outer peripheral surface of the convex portion  62  engaging protrusions  63  to be engaged with the engaging grooves  48 . Accordingly, as shown in FIG. 5B, the convex portion  62  is inserted in the coupling cylindrical member  40  and the engaging grooves  48  engage the engaging protrusions  63  and then the jig  60  is rotated whereby the coupling cylindrical member  40  can be rotated in a state of fixing the FC type receptacle housing  30 . 
     Also, although the FC type receptacle housing  10  is fixable to a member to be fixed through the fixing through-hole  17  (see FIG.  4 ), the FC type receptacle  20  can be detachably coupled to the FC type receptacle housing  10  fixed in this manner. 
     FIGS. 6A and 6B illustrate another embodiment. A universal adapter  1 B is assembled as an FC-SC connection adapter, which is assembled with the above-stated FC type receptacle housing  10  and a SC type receptacle  120 . 
     Here, the SC type receptacle  120  is similar in basic structure to the FC type receptacle  20  except for having structure connectable to an SC type optical connector plug, and identical in that it can be detachably coupled to the FC type receptacle housing  10 . 
     Here, the SC type receptacle  120  is formed by an SC type receptacle housing  130  and a coupling cylindrical member  140 . 
     The SC type receptacle housing  130  is identical to the FC type receptacle housing  30  except that it is made in a shape connectable with an SC type optical connector plug. That is, on an opposite side to a reference plane  131  of a base plate  132  having the reference plane  131  on one side, a flange portion  137  of a coupling portion  133  formed by a cylindrical member couplable with an SC type connector plug. The base plate  132  is provided with a through-hole having a smaller diameter portion  134  at its peripheral edge portion. In the reference plane  131  a ring formed reference convex portion  135  is provided that engages a reference convex portion  15  provided in the reference plane  11  of the FC type receptacle housing  10 , and a reference bore  136  for insertion of a reference pin  16  is provided in the base plate  132  and the flange portion  137 . 
     Meanwhile, the coupling cylindrical member  140  has a press-fitted pair comprising a first cylindrical member  141  and second cylindrical member  142 , and incorporates inside an optical connection sleeve  50 , such as a split sleeve. That is, the first cylindrical member  141  has an inner diameter size capable of incorporating the optical connection sleeve  50  in a play fit state. On one side an optical coupling opening  143  is provided having a greater inner diameter size than an inner diameter size of the optical connection sleeve  50  although somewhat smaller in diameter than an outer shape size of the optical connection sleeve  50 . Also, in an outer peripheral surface a male thread portion  144  is provided which is to be coupled to the female thread portion  14  of the FC type receptacle housing  10 . Meanwhile, the second cylindrical member  142  has a fitting portion  145  having an inner diameter size to allow fitting to the first cylindrical member  141 , which also has one end side an optical coupling opening  146  having generally the same size as the optical coupling opening  143 . Furthermore, a pair of engagement grooves  148  are provided in diametrically opposite positions at a peripheral edge portion of the optical coupling opening  146 . Incidentally, the first cylindrical member  141  and second cylindrical member  142  have end shapes, on the side of the optical coupling openings  143  and  146 , respectively couplable to the optical connector plugs. 
     If the first cylindrical member  141  and second cylindrical member  142  are press-fitted in a state of incorporating the optical connection sleeve  50  and the first cylindrical member  141  is inserted in the smaller diameter portion  134  of the SC type receptacle housing  130 , because the male thread portion  144  is greater in diameter than the end-portion smaller diameter portion  134  of the second cylindrical member  142 , the coupling cylindrical member  140  is rotatably engaged with and held by the SC type receptacle housing  130 . 
     The SC type receptacle  120  rotatably engaged and held with the coupling cylindrical member  140  in this manner becomes an FC-SC coupling adapter  1 B by being coupled and assembled with the FC type receptacle housing  10 . Incidentally, this assembling can be performed similarly to the one mentioned above. 
     FIGS. 7A and 7B show another embodiment. A universal adapter  1 C in this embodiment is assembled as a FC-ST connection adapter, which is assembled with the above-stated FC receptacle housing  10  and the ST type receptacle  220 . 
     Here, the ST type receptacle  220  is similar in basic structure to the FC type receptacle  20  except for having structure connectable with an ST type optical connector plug, and is identical in that it is detachably couplable to the FC type receptacle housing  10 . 
     Here, the ST type receptacle  220  is formed by an ST type receptacle housing  230  and a coupling cylindrical member  240 . 
     The ST receptacle housing  230  has generally the same shape as the FC type receptacle housing  10 . That is, on an opposite side to a reference plane  231  of a base plate  232  having the reference plane  231  on one side, a coupling portion  233  is provided that is formed by a cylindrical member having a shape couplable with a ST type optical connector plug wherein a step portion  233   c  is provided at an inward portion thereof. Meanwhile, on a reference plane  231  side of the coupling portion  233  a smaller diameter portion  234  is provided. On the reference plane  231  a ring formed reference convex portion  235  is provided which is to be coupled to a reference concave portion  15  provided on the reference plane  11  of the FC type receptacle housing  10 , and in the base plate  232  a reference hole  236  is provided which is to be fitted with the reference pin  16 . 
     Meanwhile, the coupling cylindrical member  240  has press-fitted first cylindrical member  241  and second cylindrical member  242 , and incorporates at the inside thereof an optical connection sleeve  50 , such as a split sleeve. That is, the first cylindrical member  241  has an inner diameter capable of incorporating the optical connection sleeve  50  in a play fit state. On one end side, an optical coupling opening portion  243  is provided that has an inner diameter size greater than the inner diameter size of the optical connecting sleeve  50  although somewhat smaller in inner diameter size than the outer diameter size of the sleeve  50 . Also, on an outer peripheral surface, a male thread portion  244  is provided to be coupled to the female thread portion  14  of the FC type receptacle housing  10 . Also, the second cylindrical member  242  has a fitting portion  245  having an inner diameter size to be fitted with the first cylindrical member  241 , and has on one end side an optical coupling opening portion  246  with generally the same size as the optical coupling opening portion  243  and on the outer peripheral surface a step portion  247  having a greater diameter than the inner diameter of the step portion  233   c.  Furthermore, a pair of engaging grooves  248  are provided in diametrically opposite positions in a peripheral edge portion of the optical coupling opening portion  246 . Incidentally, the first cylindrical member  241  and the second cylindrical member  242  have end shapes on sides of the optical coupling opening portions  243  and  246  respective of which can couple with the optical connector plug. 
     If the first cylindrical member  241  and second cylindrical member  242  thus formed are press-fitted in a state incorporating the optical connecting sleeve  50  and the first cylindrical member  241  is inserted in the small diameter portion  234  of the ST type receptacle housing  230 , because the male thread portion  244  is greater in diameter than the small diameter portion  234  and the step portion  247  is greater in diameter than the step portion  233 c, the coupling cylindrical member  240  is rotatably engaged with and held by the ST type receptacle housing  230 . 
     The ST type receptacle  220  rotatably engaged and held with the coupling cylindrical member  240  in this manner becomes a FC-ST coupling adapter  1 C by being coupled and assembled with the FC type receptacle housing  10 . Incidentally, this assembling can be performed similarly to the one stated above. 
     As explained above, the above-described FC type receptacle housing  10  decouplably is coupled with any of the FC type receptacle  20 , the SC type receptacle  120  and the ST type receptacle, thus structuring a universal adapter in variety of types. That is, if a universal adapter as this is used, the FC type optical connector plug can be switch-connected to an optical connector plug in variety of types. 
     Also, switch-connection having- been conventionally impossible becomes possible because replacement is possible with a receptacle in variety of kinds of a FC type receptacle  20 , a SC type receptacle  120  and a ST type receptacle  220  in a state of fixing the FC type receptacle housing  10 . 
     Naturally, the receptacle housing on the fixing side can be modified to a SC type or a ST type. Also, it is needless to say that the above-described various structures can be modified within a range of the rating of the various optical connectors and within a range not departing from the gist of the invention. Furthermore, it is naturally possible to make as an adapter for an optical connector in various kind other than the FC type, SC type and ST type. 
     As explained above, according to the universal adapter of the present invention, it is possible to easily switch over for various kinds of optical connector plugs. For example, for one kind of optical connector plug, various kinds of optical connector plugs can be switchably connected.