Optical fiber connector

Description: TECHNICAL FIELD [Detailed description of the invention]

Technical field The present invention relates to a bicone optical fiber connector that prevents damage to the end face of a plug disposed in a positioning sleeve and improves insertion loss and characteristic reproducibility. The connection of a single optical fiber cable can be made by a connector called a bicone connector. This connector includes a coupler with a housing in which a bicone positioning sleeve is disposed internally. The sleeve contains two cone-trapezoidal cylinders, which communicate with each other through a common surface, which is their smallest diameter. Each of the two optical fibers connected is terminated with a plug. Each plug has a conical trapezoidal end, which is the first pedestal, and this end is housed in each cavity of the sleeve. Each optical fiber is inserted into the plug and its end terminates in the second pedestal of the plug. The plug is held inside the cap, and the cap having a threaded portion on the outside is screwed into the threaded portion at the entrance portion of the housing. At least the conical surfaces of the plug and sleeve are designed to act as positioning surfaces and be consistent. When the cap is screwed into the housing, the plug is forced in place with respect to the wall defining the cavity in which it is housed. When two plug-terminated optical fibers are coaxially positioned and the flat ends of the optical fibers come into contact with each other on a common surface, the two connected optical fibers have the least loss. Considering an optical fiber with a core diameter of 8 microns and a clad diameter of 125 microns, for example, the task of providing a consistent plug sleeve surface to meet positioning and end face separation requirements is trivial. It's not a thing. The problem with this type of connector is related to mounting the plug inside the sleeve. Fixing the cable when rotating the cap into the housing of the connector can be very difficult, if not impossible, for some connectors. If the plug is not fixed when the cap is rotated and inserted into the housing in which the sleeve is arranged, the plug will rotate together with the cap. As the plug rotates, the end face of the plug, and thus the end face of the optical fiber terminating at it, comes into contact with the end face of the optical fiber and the plug already in the coupler, causing wear and causing damage to the optical fiber. This problem can be solved by a taper length that allows gaps to exist in both end faces. Here, the taper length is the distance from the reference periphery at the plug boundary to the end surface of the optical fiber which is the end surface of the second pedestal. However, this solution increases insertion loss. This loss provides an optical index matching material into the cavity of the sleeve and then pushes the optical fiber into the cavity to engage the end face with the conical wall to position the optical fiber and bring the end face closer. By doing so, it can be reduced. This index matching material helps reduce transmission loss, even if the end faces are not in contact. While this method can provide a suitable connection, contamination by the extra medium added to the fiber optic junction can be problematic. Another problem that arises when trying to solve the problem of careless rotation of the plug is compatibility. Since many bicone connectors are already in use, it is sensible to provide a plug that solves the unwanted rotation problem but is incompatible with the sleeves that are already in use. Clearly, prior art has not provided a method that easily solves the problem of mounting a conical trapezoidal plug that terminates an optical fiber inside a bicone coupler without wear at the end of the optical fiber. The required connector has improved loss loss and characteristic reproducibility. Desirably, the required connector plugs and sleeves are compatible with connectors already in use in the art. Outline of the invention The above-mentioned problem is solved by the optical fiber connector of the present invention. The first and first plug structures (plug assemblies) each terminate the optical fiber and have a plug. The plug has a passage in its length direction and accommodates the end of the optical fiber such that its end face terminates at the end face of the plug. Each plug structure encloses at least part of the plug and also includes a cap that is rotatable relative to the plug. At least one plug structure comprises a key that is attached to the plug and projects towards the free end of the plug to which the optical fiber terminates. The connector also includes a sweep, which accommodates the plugs of the first and second plug structures at both ends and engages the guide surface of each plug with the consistent guide surface of the sleeve. .. It has a notch in which the key engages with at least one of the ends of the sleeve, and prevents the relative rotation of the plug and the sleeve when the cap and the sleeve of the at least one plug structure perform a relative rotational movement. doing. According to one embodiment, the plug has a conical trapezoidal end connected to a cylindrical portion. The plug has a threaded portion on the outside and is attached to the cap, but the conical trapezoidal end of the plug extends from the cap. The sleeve, which has a conical trapezoidal cavity on both sides, is mounted in a binder housing with an internal screwed inlet. The screws at each inlet go inside the inlet and are far enough to engage the plug key to the outer notch of the sleeve before rotating the cap into the binder housing to secure the cap to the housing. Only the plug can be inserted. Detailed explanation With reference to FIG. 1, a bicone connector, indicated by reference number 20, as a whole is shown. The bicone connector 20, which shows the partially removed state in Fig. 2, contains the two plug structures (plug assemblies) 23, and the coupler 22 which accommodates the 23. Fig. 2 shows the vertical axis of Fig. 1. 180 around It is the figure which showed by rotating. Each plug structure 23 contains a light guide or plug 24 that terminates the optical fiber 25 (see Figure 3), and as can be seen from Figure 3, each plug 24 has a cylindrical portion 26 and an end that includes a lumen 28. It has a part 30 and. The end 30, referred to as the first pedestal, is conical trapezoidal and has a flow path 32 that communicates with the lumen 28. An integral coated optical fiber 25 jacketed with a plastic material such as polyvinyl chloride to form a cable 35 is terminated by a plug 24 (see Figure 3 again). After the jacket material and coating are removed from the end 34 of one fiber optic cable, the cable is inserted into lumen 28 and the bare end 34 is housed in the flow path 32 and the fiber optic. The end of 25 extends to the second pedestal 36. The end face of the end 34 of the optical fiber 25 coincides with the end face of the second pedestal 36. A strain removing member 38 is provided at a location exiting the cable lumen 28. Each plug 24 has a retaining ring and washer at its end 30 (see Figures 1 and 2). As can be seen from the plugs 24 shown on the left side of FIG. 1 and the right side of FIG. 2, which constitute a preferred embodiment of the present invention, the holding ring 40 includes a key 43 projecting toward the free end of the plug (FIG. 4, FIG. (See also Fig. 5), abuts on the washer 47 fixed to the plug 24. In the other plug shown on the right side of FIG. 1, the retention ring 42 is provided around the plug near the first pedestal, and the washer 45 is equipped with a key instead of the retention ring (Fig. 1A). , See also Figures 6 and 7). The washer 45 is in contact with the retaining ring 42, and the washer key 43 is in the notch 49 of the retaining ring 42 (see Figure 1A). A compression spring 44 is placed between the washer 45 and another washer 47 (see the right side of Fig. 1) or between the washers 47 and 47 (see the left side of Fig. 1) around the cylindrical portion 26 of the plug. It is stretched. The plug 24 is located at the end of the holder or cap 46, where the washer 45 and another retaining ring 42 engage the annular lip 48 to hold the plug in the cap. One side of the cap 46 includes a threaded portion 54 threaded on the outside, and an integral fiber cable 35 extends from the other side of the cap. As described above, the connector 22 connector 22 (see FIGS. 1 and 2) houses two screwed plug caps 46, 46 and two plugs 24, 24. The coupler 22 is composed of a housing 57 including two opposing cavity 58, 58 each having a threaded portion 59, which housing 57 may or may not include a flange 60 attached to a support surface. The flange 60 is positioned relative to the annular collar 62 formed inside, which extends along the longitudinal axis 64 of the connector (see FIG. 2). The housing 57 of the coupler 22 houses a positioning sleeve 66 consisting of two opposing conical trapezoidal cylinders 68, 70. Empty fuselage 68 and 70 communicate with each other on a common surface 72. Both the plug 24 and the sleeve 66 are made of, for example, a transfer molded epoxy composite filled with ground silica, while the housing 57 is made of, for example, a plastic material. However, plugs and sleeves can also be made of other materials, such as metal materials. Since the positioning sleeve 66 is disposed inside the housing 57, when the caps 46, 46 and their outer threads 54, 54 are rotationally screwed onto the inner threads 59, 59 of the fuselage 58, 58, The ends 30, 30 of the plugs attached to the corresponding caps are housed in cavities 68, 70, with the second pedestals 36, 36 near the common surface 72. Further, when the screw portions 54, 54 of the caps 46, 46 are rotationally screwed to the housing 57, the cylindrical portions 26, 26 of the plug move in the opening defined by the lips 48, 48 to move the holding rings 42, 42. To disengage the lip (see the left side of Fig. 2). The retaining ring 40 of the plug on the left side of FIG. 2 is a collar with an external screw that is rotationally screwed into the empty body 58 on the left side of FIG. 2 or the empty body on the right side of FIG. 1 to fix the sleeve 66 to the housing 57. It is in the vicinity of 74. The collar 74 is screwed and secured to the inside of the binder 22 to prevent the sleeve from inadvertently detaching from the housing, although it does not necessarily have to engage the sleeve. The spring 44 is positioned by securely engaging the plug end 30 with the wall 76 of the positioning sleeve. Further, the plug end 30 on the right side of FIG. 2 moves into the cavity 68 of the sleeve 66 and comes into contact with the wall 78. The sleeve 66 can move within the opening 79 of the collar 62, facilitating the positioning of the two plugs 24, 24. Ideally, the longitudinal axes of the plugs 24, 24 located within the sleeve 66 should be on the same axis, and the end faces of the optical fibers should have the second pedestals 36, 36 in contact with each other for minimum loss. It is in a state. The outer surface of the conical end 30 of each plug 24 and the surfaces of the sleeve cavity walls 76, 78 are positioning surfaces that are consistent with each other, and these positioning surfaces cause the conical trapezoidal end of the plug to be inside the sleeve 66. The second pedestals 36, 36 are in the desired positioning when housed in. When the plugs 24, 24 are disposed on the positioning sleeve 66, the plugs must have the required end face spacing based on the length of the cavity 68, 70. Similarly, the so-called taper length of each plug needs to be a predetermined length. As mentioned above, the taper length of the plug is defined as the distance from the reference periphery of the plug boundary to the end face of the second pedestal 36. Next, FIG. 8 shows a prior art bicone connector for reference. Corresponding elements of the connectors in Figures 8 and 1 are indicated by the same reference number. As you can imagine, if one plug 24 of a prior art connector is inserted into a prior art sleeve 80 and the cap 46 is rotationally screwed into the housing of the coupler 82, rotating the cap of the other plug will illuminate. The end faces of the fibers may wear against each other. This is because when the cap 46 is rotated, it tends to rotate unless the plug inside it is also blocked. As the plug 24 rotates, the end face of the optical fiber terminated therein may come into contact with and wear the end face of the optical fiber terminated to the opposite plug already positioned within the sleeve 66. By fixing the cable 35 of the plug structure attached to the housing 81 by the worker, it is naturally possible to prevent damage to the end face of the plug. However, this may not be done on a daily basis by the worker, and it may not be possible to secure the cable. It is considered that the connector itself needs to have a function to solve this problem. The connector 20 of the present invention is therefore provided for solving this problem. As described above, the holding ring 40 has a key 43 that projects vertically from the holding ring surface (see the plug on the left side of FIG. 1 and FIGS. 4 and 5). A retaining ring on the plug 24 projects its key 43 to the free end of the conical trapezoidal end of the plug. In a preferred embodiment, the key 43 is formed on the retention ring 40, but the key is similarly provided on the washer 45 (see the plug on the right side of FIG. 1 and FIGS. 6 and 7) or the plug 24. it can, Bei also the position of which angle the plug can be obtained. The key 43 is adapted to engage a portion of the coupler so that the plug 24 does not inadvertently rotate when the cap 46 is secured to the coupler 22. For this reason, the positioning sleeve 66 has at least one notch 86 around it (see FIGS. 1 and 2). Since the key 43 is housed in the notch 86 when the conical trapezoidal end of the plug 24 engages the wall of the sleeve, the sleeve is extended, i.e., extended longitudinally at the end that requires the notch. There is. Otherwise, the notched inlet end of the sleeve of the prior art does not extend to the inlet end of the coupler enough to accept the key 43. It is clear that notches may be provided at one end of the sleeve or at both ends of the sleeve 66 (see Figures 1, 2 and 9). If notches are provided at both ends as shown in FIG. 9, a conventional plug 24 without a key 43 can be attached. Further, when the sleeve 80 of the prior art is attached to the binder housing, the plug structure having the key 43 can be inserted into the binder housing without the key becoming an obstacle and the plug can be accommodated in the sleeve ( (See Fig. 10) is particularly clear from the above description. Next, especially referring to FIG. 1, the screw of the cap 46 of the plug structure 23 engages the housing 57 before the key 43 is housed in the notch 86, so that the operator feels that the key enters the notch. It is clear that it cannot be grasped. To solve this, the key 43 must be aligned with the notch 86 of the sleeve 66 before the cap 46 is rotationally screwed into the screwed inlet portion of the binder housing. This can be difficult in use with connectors. For example, another device may be an obstacle, making it impossible to see the end face of the connector inlet and determine the position of the notch. This problem can be solved by scraping the corresponding portion of the inlet portion of the binder housing 57. For details, cut out the screw portion 59 as shown by the reference number 88, and insert the beginning of the screw portion 59 into the cavity 58 a little. This allows the threaded portion 54 of the cap 46 to be inserted into the coupling housing 57 for a short length, stopping engagement with the threaded portion and not rotating the plug 24 until the key 43 is positioned in the notch of the sleeve. The connector 20 of the present invention is compatible with connectors existing in the art. For example, if all new jumper cables were equipped with plugs 24, 24 with keyed washers or keyed retaining rings, such plugs would be combined with the coupler housings and sleeves already installed in the field. It is important to be able to use it. The sleeves of the prior art are not expanded, i.e. not extended longitudinally to provide a notch around them. Therefore, when the keyed plug is rotationally screwed into a housing with such a positioning sleeve (see FIG. 10), the key does not engage the sleeve. As a result, the plug with the key can be attached to the sleeve of the prior art without any trouble. The modifications of the preferred embodiment described above are useful for a particular mounting structure. For example, in the housing of a device, a connector coupler 100 to 100 (11th) in which a circuit board is slidably moved to a truck and one or more connectors at one end of the board are attached to the back plate 101. It is housed in the empty fuselage (see figure). The connector coupler 100 shown in FIG. 11 typically includes a housing 102 with a flange 103 secured to the back plate. The housing 102 includes a tapered inlet 104 and an inlet 106. The wall 108 defining the entrance 106 and the empty body 107 is provided with a threaded portion 110. The positioning sleeve 112 fixed within the housing has an end 114 that faces the threaded 110 side and includes a notch 115. The collar 74 secures the sleeve 112 inside the housing 102. At the time of use, the circuit board is moved to accommodate the bicone plug at the inlets 104 to 104 of the connectors 100 to 100 attached to the back plate 101. The conical trapezoidal end of the plug is housed in the notched ends 116-116 of the positioning sleeves 112-112. Next, the plug of the keyed bicone connector is inserted into the inlets 106-106 of the connector couplers 100-100. Instead of the connector connector 100, a separable separation block 119 and a ride guide separation block 120 can be used (see Figure 12). Separation block 119 includes a support 122 having a flange 124 fixed to the back plate 101. The support 122 includes an inlet cavity 126 that houses a plug extending from the circuit board, and the separation block 119 on the opposite side of the tergum has two bends 127, 127 that are opposite to each other in the radial direction. including. Each bend 127, 127 includes a slot 128 that accommodates a snap-lock tongue piece 130 that extends radially from the housing 132 of the separation block 120. One end 134 of the housing, which is the same sleeve as used in the structure of FIG. 11 and is provided with the positioning sleeve 112 fixed by the ring 131 of the separation block 120, is housed in the cavity 133 of the support. The other end of the housing 132 is provided with an inlet 136 having an internally threaded threaded portion 138 and a machined unscrewed inlet portion 139 for accommodating a threaded cap of a keyed bicone plug. There is. In the installation of the structure of FIG. 12, the separation blocks 119 to 119 are attached to the back plate 101, and then the light guide separation blocks 120 to 120 are attached to them. A bicone plug terminating a single fiber optic cable is inserted into the inlet 136 of each separation block 120 and its cap is rotationally screwed into the housing 132. Next, the circuit board is moved to accommodate the plugs at the inlets 126 to 126 of the separation blocks 119 to 119. In another application of the present invention, the device panel 140 is used as a connecting cabinet for bulkhead mounting connectors (see Figure 13). The device panel 140 includes, for example, one or more separation blocks 141-141. A plurality of separation blocks 141 to 141 can be provided on the back plate of the housing. The input cable is pulled into a building or the like, and each fiber optic of the cable has an end terminated by a bicone connector and is connected to a single fiber optic jumper cable. Each of these bicone connectors, keyed or keyless, is inserted into the inlet end 142 of the housing 143 of the separation block 141 secured to the panel 140 via the flange 144. Note that the entrance to the separation block accommodates a keyed or unkeyed plug. As a result, the equipment panel has a large number of fibers of cables connected to the separation block array fixed to the panel. Next, to connect a specific piece of optical fiber to the device, the ride guide separation block 120, which is the separation block of FIG. 12, is connected to the snaplock tongue pieces 130, 130 into slots 128, 128. Attach it to the block already on the panel. As mentioned above, the separation block 120 includes an end 134 housed in the flange end of the separation block and another end 136 having an inlet defined by a wall with inner threads 138,138. Includes housing 132 with. The positioning sleeve 112 is fixed within the separation block 120. The positioning sleeve 112 has a notched end 114 facing the inlet end 136, which is extended from the end of the prior art positioning sleeve to include the notch 115. Also, since the inlet 136 is scraped to give the unscrewed portion 139, the beginning of the screw goes inside the housing 132. After the separation block 120 is attached to the separation block 141, the keyed plug 24 is inserted into the inlet 136 of the separation block 120 and its cap is In the installation of the structure of FIG. 13, the keyed or keyless bicone plug structure is rotationally screwed into the inlet 142 of the separation block 141 mounted on the panel 140 of the device housing. The plug housed in the inlet end 142 terminates the optical fiber of the inlet cable, which remains unused until the separation block 120 is snap-locked into the cavity 151 of the separation block 141. At this time, there is no plug on the other inlet 136 side of the separation block, and no key is required. However, when the jumper cable is attached to the inlet 136 of the separation block 120, it is desirable to use the keyed plug 24 as the plug end is connected to a positioning sleeve that already has a plug on one side, and the plug end. It is necessary to avoid damage to the part. As described above, the connector of the present invention prevents the plug from inadvertently rotating with respect to the positioning sleeve. Also, the key gives improved reproducibility because the optical fiber is positioned in the same position each time it is connected. The loss due to the fiber position of the connector reproduces the same loss each time the connector is connected because the key of the plug engages with the notch formed by enlarging the sleeve. It is clear that other structures of the key 43 are also within the scope of the present invention. For example, the key 43 can be formed integrally with the plug 24 instead of extending from the washer 45 or the holding ring 40 (see FIG. 13). Other advantages of the present invention can be understood by referring to FIGS. 14-18. As can be seen in FIGS. 14 and 15A, the center 170 of the core of the optical fiber 171 at the end face of the plug 24 on the common surface 72 is generally not located at the center 175 of the end face of the plug. Further, the center 173 of the core of the optical fiber 174 terminated by the common surface 72 is not located at the center 175 of the end face of the plug terminating the optical fiber 174. As shown in FIG. 15B, in order to facilitate the connection of both plugs with the core on the same side of the center 175 of the plug, the positioning member 176 should be oriented in a particular direction with respect to the center of the fiber optic core. Can be fixed to each plug. This positioning member, which is the key 43, is arranged radially with respect to the center of the core (see FIGS. 15B and 16), or is arranged at an angle such as 90 ° with respect to the center of the core. It can be installed (see Fig. 17). By doing so, in FIG. 15A, the center of the core is located in the opposite position in the radial direction, or on the side that is not fixed to any of the longitudinal axes 178 and 178 that pass through the centers 175 and 175 of the end face of the plug. The situation shown is avoided. The position of the positioning member can be indicated on the strain removing member 38 (see FIG. 3) or on the plug 24. The keys 43, 43 and the notched sleeve can be arranged as shown in FIG. 17, the notches 86, 86 of the sleeve are 180 ° apart, and each key is 90 ° off the center of its core. The centers of the cores appear along the axes 178 and 178 in FIG. 17, but typically the centers of these cores are offset along the plane passing through the axes 178 and 178. The notches on both sleeves are shown, but the fiber optic core is along the same radial plane. In a preferred embodiment shown in FIG. 18, each key is arranged radially with respect to the center of its core, so that, for example, the notches 86, 86 of the sleeve 66 are represented identically to each other in the plan view of the sleeve. It should be understood that the above configuration is merely for explaining the present invention. Those skilled in the art can devise other configurations within the spirit and scope of the invention by implementing the principles of the invention.

[Simple explanation of drawings]

FIG. 1 is a front view showing the assembled state of a bicone connector of an optical fiber cable, which includes a positioning sleeve and two plugs, each terminating the optical fiber. Fig. 1A is a detailed view of the holding ring located near the keyed washer. Fig. 2 is a partial decomposition view of the bicone connector in which only one plug of the bicone connector of Fig. 1 is retained in the connector housing. Fig. 3 is a detailed view of the bicone plug of the connector shown in Fig. 1 with one optical fiber terminated. Figures 4 and 5 show the end and side views of the holding ring with the lock key. 6 and 7 are end and side views of a washer with a key that locks the plug from rotating during connector assembly. Figure 8 shows the front view of a conventional positioning sleeve with the conventional plug on one side and the other conventional plugs on the other side. FIG. 9 is a front view of a positioning sleeve having key storage slots at both ends, a plug with a key inserted at one end, and conventional plugs lined up at the other end. FIG. 10 is a partial assembly of a connector of the present invention, including a plug with a lock key attached to a conventional sleeve and a plug with a key placed in a position to be inserted into the sleeve. FIG. 11 is a front sectional view of a positioning sleeve with one key containment notch located within a housing having an inner threaded portion at one end and a tapered cavity for accommodating a plug pushed into the other end. FIG. 12 is an exploded front sectional view of a positioning sleeve arranged in a snuff-coupled light beam separation block with a key containment notch and a single separation block with a tapered inlet to accommodate a plug that can be pushed in. , Figure 13 shows a positioning sleeve located on a light beam disassembly block that has a key containment notch and is snap-coupled, a separation block with an inner thread, and a key in place for insertion into the sleeve. Partial cross-sectional front view with the plug FIG. 14 is a partial front sectional view of two plugs in a conventional positioning sleeve, in which the center of the fiber optic core terminated by the plug is located in a direction that varies within the manufacturing tolerance. 15A and 15B are schematic end-views showing the center position of the fiber optic core on a common surface in the structure of FIG. 14 and the structure in which the keyed plug and the notched positioning sleeve are used. FIG. 16 is a partial cross-sectional front view of a sleeve having a notch at each end and two plugs each having a key whose core center is positioned along a common radial plane. FIG. 17 is a partial cross-sectional front view of the positioning sleeve and the two plugs in it, with the core positioning members offset 180 ° from each other and the center of the fiber optic core positioned to minimize insertion loss. And FIG. 18 is a diagram showing a preferred embodiment of the sleeve of the present invention in which a notch positioned at the center of the core is arranged along a common radial plane. 20 ...... Connector, 23 ...... Plug structure (plug assembly), 24 ...... Plug, 25 ...... Optical fiber, 30 ...... 1st pedestal (end), 36 ...... 2nd pedestal, 40, 42 ... holding ring, 45, 47 ... washer, 43 ... key , 44 ... compression spring, 46 ... cap, 57 ... housing, 58 ... empty body, 60 ... flange, 68, 70 ...... empty body, 66 ...... positioning sleeve, 72 ...... common surface, 74 ...... color.