Abstract:
The invention relates to a device for splicing fiber optic lines having a first and second holder for direct or indirect receiving of at least one fiber optic line each, an alignment means for aligning the ends of the fiber optic lines received in the first and in the second holder to one another and electrodes in the region of the ends of the fiber optic lines aligned to one another for creating a slice connection. The two holders on one side and the alignment means and preferably the electrodes on the other side can move relative to one another between a splicing position and a release position such that the splice connection is released in the release position.

Description:
This is a National Phase Application filed under 35 U.S.C. §371 as a national stage of International Application No. PCT/EP2010/053071, filed on Mar. 11, 2010, claiming the benefit from Swiss Patent Application 00432/09, filed on Mar. 20, 2009, the content of each of which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present invention relates to a device and a method for splicing optical fibers, and to the use of an end piece in a device for splicing. 
     Numerous devices for splicing optical fibers are already known and widely used. A common feature of all these devices is that, after the splicing, the spliced connection must be removed from the device and, in an additional step, this spliced connection must be provided with a mechanical protective device. Since the optical fiber ends that are to be spliced must be free of any outer sheath and any protective sleeve before the splicing, the optical fiber ends thus exposed, and in particular the spliced connection, are fragile and very sensitive to improper handling. 
     For example, DE 10 2006 036 330 A1 shows a portable splicing unit with holding devices for receiving two pieces of optical fiber to be spliced to one another. After the splicing, the pieces of optical fiber are removed from the holding devices and fed to a shrinking oven by means of a pivotable bracket. 
     WO 2004/001471 A1 discloses a method for splicing two optical fiber ends, the one optical fiber end being preassembled in a plug-in connector part. In this case, a pin holder of the connector part and a cable end are clamped in such a way that the two optical fiber ends lie coaxially with respect to one another on a centering block. After the splicing, the pin holder and the cable end are removed from the centering block in the clamped state, in particular are raised. Subsequently, a mechanical protection is applied to the splice. The disadvantage of this method is that the unprotected splice has to be moved, which can easily lead to the splice being damaged. 
     BRIEF SUMMARY 
     It is therefore an object of the invention to provide a device and a method which make it possible for a mechanical protection to be applied to the spliced connection after the splicing without separate handling of the spliced optical fibers. This object is achieved by the device and the method with the features of claims  1  and  11 . 
     A device according to the invention for splicing optical fibers has a first and a second holder for directly or indirectly receiving at least one optical fiber each. Thus, it is conceivable, for example, that the optical fiber is clamped in an intermediate piece and the intermediate piece is received in the holder. Such an intermediate piece may be, for example, a connector or a connector part. Alternatively, it is also conceivable that the intermediate piece consists of a sheath of a fiber-optic cable. The device also has an aligning means, which serves for the precise alignment of the ends of the optical fibers received in the holders. Such an aligning means may, for example, have a V-shaped groove. Furthermore, the device has electrodes, which are located in the region of the mutually aligned ends of the optical fibers. To create the spliced connection, the electrodes are connected to a high-voltage source, so that an arc is produced between the electrodes. The two holders on the one hand and the aligning means, and preferably the electrodes, on the other hand are movable in relation to one another, between a splicing position and a releasing position, in such a way that, in the releasing position, the spliced connection is released and is consequently freely accessible for further processing steps. It is irrelevant in this respect whether the two holders move simultaneously away from the electrodes and the aligning means, or whether the electrodes and the aligning means move away from the two holders. Furthermore, it is also conceivable that the aligning means can be moved away from the two holders in one direction and the electrodes can be moved away in other directions. Apart from movement in a straight line, which may take place in any of the three axes, swiveling movements about a fixed axis or even combinations thereof are also conceivable. 
     In the releasing position, the spliced connection is released, and accessible, with respect to the longitudinal axis of the optical fibers over an angle of almost 360°. As will be evident, this allows protective sleeves or the like to be applied as long as the optical fibers are still firmly clamped. An inspection of the spliced connection before removal from the device is also made much easier. 
     The aligning means and the electrodes are, for example, advantageously arranged on a splicing module mounted between the holders. By moving this splicing module away from the relatively fixed holders, the aligning means and the electrodes are consequently moved simultaneously. Preferably, the splicing module is thereby lowered. Combinations of movements, such as lowering and displacing or swiveling and displacing, are likewise possible. Other combinations of movements are not ruled out. The relatively fixed holders have the advantage that clamped fiber-optic cables do not have to be moved. It is also advantageous for reasons of stability of the unit that the splicing module is pressed downward, that is to say against the underlying surface. 
     The splicing module is preferably moved from the splicing position into the releasing position against a prestressing force. Furthermore, it is advantageous if the splicing module can be arrested in the releasing position. For this purpose, the splicing module may, for example, be prestressed in the splicing position by a spring and be arrested in the releasing position by a simple snapping function. Alternatively, a combination of a spring and a shock absorber may be used, the shock absorber being designed such that the shock absorber valve is closed in the releasing position. Not only a hydraulic shock absorber but also a pneumatic shock absorber or a mechanical shock absorber may be used. It has proven to be advantageous if an arresting device which automatically releases the arrestment when there is pressure against the prestressing force is used for arresting in the releasing position. Apart from the known ballpoint pen mechanism, a person skilled in the art is familiar with other solutions. With the aid of this arrangement, the splicing module can be moved back again immediately into the splicing position. It goes without saying that motorized displacement of the components would also be possible. 
     The holders for receiving the optical fibers may each be arranged on a carrier unit and releasably connected to it. A screw connection, for example, represents such a releasable connection. Alternative solutions, for example combinations of positioning pins, magnetic connections and securing levers, are likewise conceivable and known to a person skilled in the art. Thus, the holders can be quickly exchanged if the device is to be converted for other optical fibers. 
     The carrier units may lie on planes which can be tilted in relation to one another. This allows an angled position between the optical fibers. This angled position makes it easier to align the ends of the optical fibers by means of the aligning means. 
     The carrier units are in this case mounted on a horizontal spindle, which is perpendicular to the axes of the optical fibers to be received in the holders. It has been found in this respect that an angle between the axes of the optical fibers to be spliced of between 170° and 180°, in particular between 174° and 178°, is advantageous. 
     To reach the releasing position, the carrier units may be in operative connection with the movement mechanism in such a way that the carrier units tilt as they move from the releasing position into the splicing position. This operative connection has the effect of ensuring said angled position automatically without any influence being brought to bear by the user. 
     One of the two holders may have a recess in which an end piece can be received with an exact fit. An exact fit is understood here as meaning that the end piece is received and fixed in the holder without any play, but without completely enclosing the end piece. This end piece contains an optical fiber, which is preferably prefabricated. Thus, for example, a plug-in connector part with a prefabricated optical fiber stub may be received by the recess. In this case, this plug-in connector part and the optical fiber are prepared in such a way that one end of the optical fiber comes to lie in the region of the electrodes. 
     In a method according to the invention for splicing optical fibers by a device for splicing, optical fibers are placed directly or indirectly into a first and a second holder of the device. Furthermore, the ends of the optical fibers placed in the holders are aligned with one another in an aligning means. By producing an arc between two electrodes, a spliced connection is obtained by splicing the ends of the optical fibers. After the splicing, the spliced connection is released between a splicing position and a releasing position by a relative movement of the two holders on the one hand and the aligning means, and preferably the electrodes, on the other hand. Now a mechanical protection can be applied to the spliced connection. As the final step, the optical fibers are removed from the holders of the device. The fact that the spliced connection is released and provided with a mechanical protection after the splicing means that it can be removed from the device without any risk of the spliced connection or the optical fiber being damaged by improper handling. 
     It has proven to be advantageous that, before and during the application of the mechanical protection, the optical fibers are subjected to a predefined tensile stress. This can ensure that the optical fibers, and in particular also the spliced connection, are enclosed optimally, in particular in the stretched state, by the mechanical protection. 
     For releasing the spliced connection after the splicing, the aligning means, and preferably the electrodes, may be lowered. However, it is also conceivable that only the aligning means are lowered, and the electrodes are laterally displaced. 
     It goes without saying that other combinations of movements are also conceivable. 
     In an aforementioned device for splicing optical fibers there may be used, in particular, an end piece that has an optical fiber which is prefabricated in the end piece and accessible on one side of the end piece, as well as sheath parts which can be connected to the end piece or are connected thereto by way of a joint. In this case, the sheath parts are closed around the spliced connection and connected to one another in the releasing position after the splicing. 
     Further individual features and advantages of the invention emerge from the description which follows of an exemplary embodiment and from the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a device according to the invention with an open protective cover, 
         FIG. 2  shows a section through the device according to  FIG. 1  along the axis of the electrodes, 
         FIG. 3  shows a section through the device according to  FIG. 1  along the axes of the optical fibers, the device being shown in the splicing position, 
         FIG. 4  shows the section according to  FIG. 3 , the device being shown in the releasing position, 
         FIG. 5  shows a prefabricated optical fiber end piece before placement in a holder, 
         FIG. 6   a  shows a view of a holder for an end piece with an open closure flap, 
         FIG. 6   b  shows a view of the holder according to  FIG. 6   a , the closure flap being closed, 
         FIG. 7  shows an enlarged view of the device according to  FIG. 1 , the protective cover and the closure flaps of the holders having been removed, 
         FIG. 8  shows the view according to  FIG. 7 , the device being in the releasing position, 
         FIG. 9  shows the view according to  FIG. 8 , the sheath parts of the end piece having been closed around the splice, and 
         FIG. 10  shows an enlarged view of the working region of the device according to  FIG. 1 , the fiber holding-down means of the protective cover being shown separately. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a view of a device  1  according to the invention with a housing  2  and an open protective cover  3 . Attached to the housing  2  on the front side is a display  4  and an operating unit  5 . Two holders  30 ,  40  can be seen in the working region. The holder  40  is configured such that it receives a prefabricated end piece and fixes it by means of the closure flap  41 . The holder  30  is designed for receiving an optical fiber, which is fixed by the closure flap  32 . A fiber holding-down means  9 , which presses the fibers into corresponding aligning means  22  (see  FIG. 8 ) between the holders ( 30 ,  40 ) during the splicing operation, can also be seen in the protective cover  3 . 
     In  FIG. 2 , a section through the device  1  according to  FIG. 1  along the axis of the electrodes  21  is shown. Arranged inside the housing  2  is a camera  23 , which shows the precise alignment of the optical fibers to be spliced on the display  4 . A splicing module  20  comprises the aligning means  22  and the electrodes  21  for splicing. The splicing module  20  is also provided with a linear guide  26  (see  FIG. 4 ), two arresting devices  25  and a shock absorber  24 . The linear guide allows lowering of the splicing module  20 , so that, after the splicing operation, the optical fibers and the spliced connection can be released. The shock absorber  24  with its retarding function prevents abrupt lowering of the splicing module  20 . The arresting devices  25  serve on the one hand for arrestment in the releasing position and on the other hand, by means of a built-in spring element, serve for the automatic displacement into the splicing position after the release of the arrestment. A battery unit  7  serves for supplying power to the camera  23 , the display  4 , a high-voltage generator  6  (see  FIG. 3 ), a lighting means  8  integrated in the protective cover  3  and electronics for the control and evaluation. The splicing operation may be initiated by pressing the corresponding buttons in the operating unit  5 . The fiber holding-down means  9 , which fixes the optical fibers on the aligning means during the splicing, can be seen in the protective cover  3 . 
       FIG. 3  shows a section through the device  1  according to  FIG. 1  along the axes  34  and  44  of the optical fibers. The device  1  is shown with the splicing module  20  in the splicing position, i.e. the splicing module  20  is aligned such that an axis through the electrodes  21  intersects the axes  34  and  44  of the optical fibers. The optical fibers are received on both sides of the electrodes  21  by holders  30 ,  40 . 
     The holder  30  is in this case designed such that it can receive an optical fiber  33  directly and fix it on the holder  30  by closing of the closure flap  32 . The holder  40  is designed such that it can receive a prefabricated end piece  50  and fixes this end piece  50  by closing of the closure flap  41 . The two holders  30 ,  40  are each arranged on a carrier unit  10  and releasably connected to it. In this case, the two carrier units  10  are mounted such that they can tilt on a horizontal spindle  11 . The carrier units  10  are operatively connected to the splicing module  20  by side pins  27  such that a movement of the splicing module  20  from the releasing position into the splicing position brings about tilting of the two carrier units  10 . This tilting of the carrier units  10  has the effect that the optical fibers to be spliced are brought together at an angle. In this case, the angle between the axes  34 ,  44  of the optical fibers to be spliced is 170° to 180°, preferably 174° to 178°. A fine adjusting means  13 ,  13 ′ serves for bringing each of the optical fibers precisely together. With these fine adjusting means  13 ,  13 ′, the ends of the optical fibers  33 ,  52  can be brought together exactly by displacement of the position of the carrier units  10 , and consequently of the holders  30 ,  40  and of the optical fibers  33 ,  52  received therein, parallel to the axes  34 ,  44  of the optical fibers  33 ,  52 . Serving for checking the position of the optical fibers is the camera  23  (see  FIG. 2 ), which transmits the image to the display  4  (likewise  FIG. 2 ). Serving for supplying the appropriate high voltage to the electrodes  21  for the splicing operation is the high-voltage generator  6 , which draws its energy from the battery unit  7 . 
     In  FIG. 4 , the device  1  is shown in a way corresponding to  FIG. 3 , the splicing module  20  being in the releasing position and arrested by the arresting devices  25 . The movement of the splicing module  20  from the splicing position into the releasing position is made possible by a linear guide  26  and is retarded by a shock absorber  24 . In the exemplary embodiment shown, the splicing module  20  has been lowered. This lowering of the splicing module  20  also brings about a lowering of the side pins  27 , which in turn are in operative connection with the carrier units  10 . This allows the carrier units  10  to be brought from their tilted position back into the horizontal. Because the spindles  11  of the carrier units  10  lie lower than the optical fibers  33 ,  52  clamped in the holders  30 ,  40 , said carrier units, and in particular also the spliced connection  15 , are subjected to a presettable tensile loading. This tensile loading is chosen here such that the optical fibers  33 ,  52  and the spliced connection  15  are optimally tensioned for the subsequent application of a mechanical protection. 
     In  FIG. 5 , a prefabricated optical fiber end piece  50  is shown before placement in a holder  40  (see  FIG. 6   a ). The end piece has a plug-in connector pin  51 , in which an optical fiber  52  is cemented. The end piece  50  is provided with two sheath parts  57 , which are each connected to the end piece  50  by means of a joint  58 . The sheath parts  57  can be swung together, so that they enclose the optical fiber  52 . The inner sides of the sheath parts  57  are each provided with an adhesive layer  59 , which is covered by a protective film  60 . The optical fiber  52  protrudes from the end piece  50  on the side opposite from the plug-in connector pin  51 . In this case, this optical fiber  52  is dimensioned such that its end comes to lie approximately centrally between the sheath parts  57  when they are swung together. 
       FIG. 6   a  shows a holder  40  for receiving a prefabricated end piece  50  with an open closure flap  41 . The holder  40  has a recess  42 , which corresponds at least partially to the contours of the end piece  50 . For precise guidance of the end piece  50 , formed in the recess  42  is a connector pin receptacle  43 , which receives the plug-in connector pin  51  of the end piece  50  and at the same time protects it from environmental influences. The prefabricated optical fiber  52  protrudes from the end piece  50  and also from the holder  40 . The end piece  50  is only partially received by the holder  40 . Along with the optical fiber  52 , the two sheath parts  57  also protrude from the holder  40 . In order to make the optical fiber  52  accessible for the splicing operation, the two sheath parts are connected to the end piece  50  by a joint. This makes it possible for the two optical fiber  52  to extend laterally away from the optical fiber  52  and, as shown, assume an angled-away position. 
       FIG. 6   b  shows the holder  40  according to  FIG. 6   a , but with a closed closure flap  41 . All that can be seen of the end piece are the two sheath parts  57 , which allow the mechanical protection of the spliced connection after the splicing, and the optical fiber  52 , which protrudes from the holder  40 . The sheath parts  57  are provided with an adhesive layer  59 , which is protected by a peel-off protective film  60 . 
     In  FIG. 7 , an enlarged view of the working region of the device  1  according to  FIG. 1  is shown. In this case, the protective cover and the two closure flaps of the holders  30 ,  40  have been removed. The splicing module  20  is in the splicing position. The two holders  30 ,  40  have each been placed on their carrier units  10 . The planes of the two carrier units  10  have been tilted with respect to one another. An end piece  50  has been placed in the holder  40  and the two sheath parts  57  of the end piece  50  have been greatly angled away, so that the optical fiber  52  protrudes freely between the electrodes  21  of the splicing module  20 . In the holder  30 , an optical fiber  33  has been placed in a groove  31 . The two optical fibers  52 ,  33  are aligned with one another in the region between the electrodes  21  by an aligning means  22  in the form of a V-shaped groove. An axial alignment takes place with the aid of the fine adjusting means  13 ,  13 ′ (see  FIG. 3 ). Serving for visually checking the alignment is the camera  23  (see  FIG. 2 ), which shows the ends of the two optical fibers  52 ,  53  in magnified form on the display  4  (see  FIG. 2 ). In order that the camera has sufficient light to detect the two optical fibers  33 ,  52 , a light-emitting diode  8  is integrated as a lighting means in the protective cover  3  (see  FIG. 2 ). This light-emitting diode  8  is shown floating freely, but in reality is integrated in the protective cover. 
       FIG. 8  shows the view according to  FIG. 7 , the splicing module  20  being shown in the releasing position. The electrodes  21  and the aligning means  22  have been lowered with the splicing module  20 . The spliced connection  15  has been released and the two sheath parts  57  are still angled away from the spliced connection  15 . Peeling off the protective films  60  from the adhesive layers  59  of the sheath parts  57  exposes the adhesive layer  59 , which adhesively bonds the two sheath parts  57  to one another and securely encloses the spliced connection when said sheath parts are swung together. 
       FIG. 9  shows the view according to  FIG. 8 , but with the sheath parts  57  closed. The splicing module  20  with the electrodes  21  and the aligning means  22  is still lowered in the releasing position. The two sheath parts  57  of the end piece  50  have been swung together and adhesively bonded. They provide both mechanical protection and protection from athmospheric conditions and environmental influences, such as for example from moisture and dust. Opening the closure flap (not represented) of the holder  40  and the closure flap  32  of the holder  30  allows the ready-prefabricated end piece  50  with the spliced optical fibers to be removed. As this happens, the closed sheath parts  57  prevent the sensitive spliced connection from being damaged. 
     In  FIG. 10 , a further enlarged view of the working region of the device  1  according to  FIG. 1  is shown. The fiber holding-down means  9 , which is integrated in the protective cover  3  (see  FIG. 2 ), is shown separately here. This fiber holding-down means  9  serves for fixing the two optical fibers  33 ,  52  in the aligning means  22  during the splicing. In this case, the fiber holding-down means  9  has contact elements in roller form, which are mounted in a floating manner and fix the optical fibers  33 ,  52  in the V-shaped groove of the aligning means  22  in the region of the ends of the optical fibers  33 ,  52 .