Abstract:
The invention relates to an optical fiber plug connector, comprising at least one pair of plug connectors and a coupling, whereby each plug connector comprises a ferrule, each two ferrules of a pair of plug connectors are detachably guided and aligned together within a guide sleeve and the coupling has a housing, for each of the plug connectors. According to the invention, a compact space-saving optical fiber plug connector made from few components may be achieved, whereby the coupling is made from only one component.

Description:
This application is a Continuation of U.S. Ser. No. 10/591,647, filed 2 Jun. 2007, now issued as U.S. Pat. No. 7,419,309, which is a National Stage of PCT/E2005/001990, filed 25 Feb. 2005, which claims priority to Ser. No. 10 2004 013 905.9, filed 17 Mar. 2004 in Germany, and which applications are incorporated herein by reference and a claim of priority to all is made. 

   TECHNICAL FIELD 
   The present invention relates to an optical fiber plug-in connection comprising at least one pair of plug-in connectors and a coupling. 
   BACKGROUND 
   In optical transmission technology, there is often the task of accommodating a number of individual optoelectronic or optical components in a confined space and in such cases connecting their pigtails in such a way that only a small amount of additional space is required for this. An actual example is a printed circuit board with a number of optoelectronic components (for example laser diodes or photodiodes) and also passively optical fiberoptic components (for example couplers, splitters, wavelength multiplexers). A further example is an Ethernet transceiver module, in which a number of laser diode modules and receiving diode modules and also an optical multiplexer/demultiplexer pair are accommodated in a standardized compact module housing. The individual components in all these cases are provided with pigtails, which have to be connected to one another on the printed circuit board or within the module housing with a minimal space requirement. The optical fibers are in this case either only provided with a primary coating (typical diameter 245 μm) or formed as secondary coated fibers (typical diameter 900 μm). In many cases, flexibility is desired for these connections, allowing individual ones to be disconnected and reconnected, for example for measuring purposes. 
   An optical fiber plug-in connection of the generic type is already known from the reference WO 03/076997 A1. This plug-in connection comprises a two-part coupling and a number of plug-in connectors which can be inserted between the coupling parts. The coupling is in this case made up of an upper part and a lower part, which are aligned with respect to each other during assembly by guiding means (for example guiding pins) and are connected to each other for example by screwing. Once the two coupling parts have been connected to each other, the plug-in connectors can be respectively inserted between the coupling parts through corresponding inlet openings on the opposing longitudinal sides. The coupling parts have for this purpose inner insertion channels corresponding to the number of suitable plug-in connectors. In an insertion channel, two plug-in connectors are guided and aligned coaxially in relation to each other, so that their ferrule end faces abut resiliently within a guiding sleeve. The plug-in connectors have in this case a securing means in the form of a frame, in which the ferrules provided with a flange (diameter 1.25 mm) are spring-mounted. Attached to the rear part of the securing means is a crimping neck, which allows cable strain-relieving elements to be anchored on the plug-in connector by means of crimping. For each plug-in connector there is an opening in the upper part of the coupling. Through this opening, a latching element arranged on the plug-in connector can be unlocked by means of a tool if the plug-in connector is to be pulled out of the insertion channel. In the case of this optical plug-in connection, the plug-in connectors can be individually accessed as desired. 
   A disadvantage of this optical fiber plug-in connection is that the coupling comprises an upper part and a lower part and a number of fastening parts, which are necessary for connecting and putting together the upper part and lower part. For instance, the upper part and lower part must be aligned exactly with respect to each other and connected to each other by means of a number of screw connections. The production of the parts and their assembly involve considerable effort. Likewise, the plug-in connector is provided with a series of components, which have to be individually created for the plug-in connector system described. For instance, the possibility of crimping strain-relieving elements on the connector parts must be provided. 
   It is therefore the object of the present invention to provide a compact, space-saving optical fiber plug-in connection which comprises only few components. 
   The optical fiber plug-in connection according to the invention has in particular the advantage that the coupling comprises only a single component and can consequently be produced and assembled in a simple manner. Putting together the optical fiber plug-in connection no longer involves complex assembly operations. The optical properties of the connections (attenuation, return loss) and also their climatic and mechanical stability (vibration, impact loading) correspond to those of a high-grade optical plug-in connection, as required for the corresponding application in transmission technology. 
   SUMMARY 
   Further advantageous refinements of the invention emerge from the subclaims. 
   For instance, the sleeve receptacles and receptacles for the plug-in connectors are integrated within the coupling and constructed in a simple form in production engineering terms. 
   The plug-in connectors of a pair are aligned coaxially with respect to each other and detachably fixed within the coupling by means of a latching device, so that access to individual pairs of fibers of those connected is possible according to choice. 
   According to an embodiment, there is the advantage that each plug-in connector has an arresting part with a T-shaped attachment, which engages in the guiding groove of the coupling. As a result, the plug-in connector is mounted and guided in the coupling and the ferrules are mounted and guided in the guiding sleeve in a very simple way, the two ferrule end faces of a pair of plug-in connectors abutting resiliently on account of the compression springs within the guiding sleeve. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained in more detail below on the basis of an exemplary embodiment represented in the drawings, in which: 
       FIG. 1  shows a perspective view of an optical fiber plug-in connection with a coupling and eight pairs of plug-in connectors; 
       FIG. 2  shows a perspective view of a plug-in connector. 
   

   DETAILED DESCRIPTION 
   In  FIG. 1 , an optical fiber plug-in connection  1  is shown as a multiple optical fiber plug-in connection for eight pairs of plug-in connectors  3 . The optical fiber plug-in connection  1  comprises a coupling  2  with plug-in connectors  3  arranged therein. The coupling  2  comprises a base plate  23  and two side walls  24 , so that two receptacles  20 ,  21  lying opposite each other are formed for the plug-in connectors  3 . Additionally provided, centrally between the receptacles  20 ,  21  is a sleeve receptacle  19 , which in  FIG. 1  is represented partly in a broken-open view to illustrate the position and arrangement of the guiding sleeves  5  inserted into the sleeve receptacle  19 . The sleeve receptacle  19  additionally has four through-bores  25 , so that either a number of couplings  2  can be screwed to one another, lying one on top of the other, or a single coupling  2  can be screwed onto a plate (not represented). 
   Each plug-in connector  3 , which is also shown in  FIG. 2 , comprises a ferrule  4 , a ferrule flange  7  and an arresting part  10 . As explained in more detail later, the end of the optical fiber  18  is cemented into the ferrule  4 , with primary or secondary coated optical fibers being used in particular. 
   In the coupling  2 , the plug-in connectors  3  are respectively connected to one another in pairs. Each plug-in connector  3  of a pair is in this case positioned into the separate first and second receptacles  20 ,  21 . The coupling  2 , acting together with the plug-in connectors  3 , has the task of aligning the ferrules  4  of a pair of plug-in connectors  3  with respect to each other and pressing them together with the required compression force. For the necessary compression force—as shown in FIG.  2 —the plug-in connector  3  is provided with a compression spring  17 , which is pushed onto the ferrule extension  9 . (The permissible tolerance range for the compression force in the case of all standardized optical plug-in connectors with cylindrical zirconium ferrules is fixed and is instrumental in reliably maintaining the optical data of the plug-in connection). Serving for the alignment of the ferrules  4  are the guiding sleeves  5 , which are customary in the case of optical fiber plug-in connectors with a cylindrical ferrule. 
   The guiding sleeves  5  are accommodated in the central region of the coupling  2 , in the sleeve receptacle  19 . For this purpose, the sleeve receptacle  19  is provided with a series of equidistant bores  6 , in which the guiding sleeves  5  are accommodated in a protected manner in the inserted state of the plug-in connectors  3  (with lateral play in relation to the walls of the bores). 
     FIG. 2  shows an optical fiber  18  prepared for use with the optical fiber plug-in connection and fabricated with a plug-in connector  3 . The end of the optical fiber  18  freed of the coating is cemented in the ferrule  4  provided with a ferrule flange  7 , in a way corresponding to the customary technique used when fabricating optical fiber connectors. The ferrule flange  7  is formed in the front region as a square  8  and in the rear part as a cylindrical ferrule extension  9 , which serves as a guide for the compression spring  17  and receives in its interior the adhesive that is used to ensure adequate strain relief of the optical fiber  18  provided with a primary or secondary coating. The flanged ferrule (diameter 1.25 mm) is the same design as that used in the case of an optical fiber connector of the LC type. However, in principle a different 1.25 mm ferrule provided with a flange, of the SFF (Small Form Factor) connector type or some other type (for example MU or LX.5), may also be used. The ferrule end face  11  is provided during fabrication with a suitable polish (for example PC or UPC), as also applied in the fabrication of a customary connector. Furthermore, during fabrication, the compression spring  17  and the arresting part  10  are pushed onto the optical fiber  18  before the end of the optical fiber  18  is cemented into the ferrule  4 . 
   To establish a connection between two plug-in connectors  3 , firstly a guiding sleeve  5  is pushed onto one of the ferrules  4  of a pair of plug-in connectors  3 . The ferrule  4  with the guiding sleeve  5  is then introduced into a free bore  6  of the sleeve receptacle  19  of the coupling  2 , with the plug-in connector being placed into the first receptacle  20 . After compressing the compression spring  17  by a defined amount, the T-shaped attachment  12  formed at the bottom of the arresting part  10  can be introduced into the correspondingly shaped guiding groove  13  in the coupling  1  and arrested there by pushing it back in the axial direction. The compression spring  17  respectively strikes against the square  8  and the arresting part  10 . Once the plug-in connector  3  of the other side has been placed into the second receptacle  21  and the flanged ferrule  4  of the other side introduced into the bore  6  and arrested in the same way, the two compression springs  17  provide the correct compression force between the two ferrules  4  of a pair of plug-in connectors  3 . The two ferrule end faces  11  then abut resiliently under pressure. 
   To disconnect a connection between two plug-in connectors  3 , the tool  14  represented in  FIG. 1  is used, with which the arresting part  10  is released from the guiding groove  13  by pressure in the axial direction against the spring tension. For this purpose, the tool  14  is provided in the front region with two lugs  15 , which engage in corresponding clearances  16  in the arresting parts  10 . 
   Apart from the ferrules  4  with PC or UPC polish, the optical fiber plug-in connection may also be used for the connection of obliquely polished APC ferrules. For this purpose, a step  22  is formed on both sides of the sleeve receptacle  19 . This step  22  provides the required twist prevention of the ferrules  4 , since the square  8  of the ferrule flange  7  rests on this step  22  in the inserted state of the plug-in connector  3 , and the plug-in connector  3  consequently cannot twist. 
   For a connection to be established more efficiently, it is also conceivable to combine a group (for example four) of plug-in connectors  3  that are adjacent in the optical fiber plug-in connection  1  by means of the arresting parts  10  to form a single part and in this way collectively establish the connection for the group of plug-in connectors concerned in a single operation. 
   Furthermore, it is possible in principle to dispense with the compression springs  17  on one side of the optical fiber plug-in connection  1 , since the required compression force between the ferrules  4  can also be ensured with in each case only one compression spring  17  per connected pair of plug-in connectors. The flanged ferrules  4  are then arrested on one side of the optical fiber plug-in connection  1  by suitable means without springing, in such a way that they cannot move back in the axial direction when the ferrule  4  is introduced on the other side. For this purpose, arresting parts  10  similar to those on the sprung other side can be used. 
   In principle, the construction of the optical fiber plug-in connection  1  is possible in its smallest configuration in such a way that, by contrast with the exemplary embodiment represented, only a single pair of plug-in connectors  3  is inserted into the coupling  2 . Any desired multiples of pairs of plug-in connectors  3  are conceivable, with the coupling  2  being formed in a way corresponding to the number of pairs of plug-in connectors  3 . 
   LIST OF DESIGNATIONS 
   
       
         1  optical fiber plug-in connection 
         2  coupling 
         3  plug-in connector 
         4  ferrule 
         5  guiding sleeve 
         6  bore 
         7  ferrule flange 
         8  square 
         9  ferrule extension 
         10  arresting part 
         11  ferrule end face 
         12  T-shaped attachment 
         13  guiding groove 
         14  tool 
         15  lugs 
         16  clearances 
         17  compression spring 
         18  optical fiber 
         19  sleeve receptacle 
         20 ,  21  receptacle for plug-in connector 
         22  step 
         23  base plate 
         24  side walls 
         25  through-bores