Patent Application
20140037250
1. Field of the Invention
The present invention is directed to an optical fiber connector and method for terminating a jacketed optical fiber cable in the field.
2. Related Art
Mechanical optical fiber connectors for the telecommunications industry are known. For example, LC, ST, FC, and SC optical connectors are widely used. However, commercially available optical fiber connectors are not well suited for field installations. Typically, an adhesive is required to mount these types of connectors on to an optical fiber. This process can be awkward and time consuming to perform in the field. Also post-assembly polishing requires that the craftsman have a higher degree skill.
Also known are hybrid optical fiber splice connectors, as described in JP Patent No. 3445479, JP Application No. 2004-210251 (WO 2006/019516) and JP Application No. 2004-210357 (WO 2006/019515). However, these hybrid splice connectors are not compatible with standard connector formats and require significant piecewise assembly of the connector in the field. The handling and orientation of multiple small pieces of the connector can result in incorrect connector assembly that may either result in decreased performance or increase the chance of damaging the fiber.
More recently, U.S. Pat. No. 7,369,738 describes an optical fiber connector that includes a pre-polished fiber stub disposed in ferrule that is spliced to a field fiber with a mechanical splice. Such a connector, called an NPC, is now commercially available through 3M Company (St. Paul, Minn.).
According to a first aspect of the present invention, an optical fiber connector for terminating a jacketed optical fiber cable is provided. The optical fiber connector includes a housing configured to mate with a receptacle. The optical fiber connector also includes a collar body disposed in the housing, wherein the collar body includes a fiber stub disposed in a first end portion of the collar body. The fiber stub is mounted in a ferrule and has a first end proximate to an end face of the ferrule and a second end. The collar body further includes a mechanical splice device disposed in a portion of the collar body, where the mechanical splice device is configured to splice the second end of the fiber stub to an optical fiber from the jacketed optical fiber cable. The optical fiber connector also includes a backbone to retain the collar body within the housing, the backbone including a cable jacket clamping portion to clamp a cable jacket that surrounds a portion of the optical fiber upon actuation. The optical fiber connector also includes a boot attachable to a portion of the backbone, wherein the boot actuates the cable jacket clamping portion of the backbone upon attachment to the backbone. The optical fiber connector also includes a tube or sheath configured to protect an exposed portion of the optical fiber. The tube or sheath can be positioned such that a portion of the tube or sheath is disposed underneath the attached boot.
According to another aspect of the present invention, a method for terminating a jacketed optical fiber cable in an optical connector having a fiber stub and a cable jacket clamp is provided. The jacketed optical fiber cable includes an optical fiber, a buffer coating surrounding the optical fiber, a cable jacket surrounding the buffer coating, and strength members axially disposed between the cable jacket and buffer coating. The method comprises removing a portion of the fiber cable jacket at the terminal end of the jacketed optical fiber cable. The method further comprises slitting a portion of the fiber cable jacket along its axial length to form a slit portion of the cable jacket that is axially disposed between an intact portion of the cable jacket nearest the terminal end of the fiber cable, the intact portion called a jacket band, and the remainder of the cable jacket. The jacket band is pulled back along the axial length of the optical fiber cable away from the terminal end of the fiber and towards the remainder of the cable jacket such that the slit portion expands outward from the optical fiber cable exposing the buffer coating and strength members. The terminal end of the optical fiber is prepared and is coupled to the stub fiber to form a splice between the terminal end of the fiber and the stub fiber. The method further includes sliding the jacket band toward the splice such that the slit portion is substantially returned to its pre-expanded shape, wherein at least a portion of the jacket band is disposed within the cable jacket clamp. A protective tube is placed over the jacket band and slit portion. A boot is secured over the cable jacket clamp to clamp the cable jacket clamp onto the protective tube and to secure strength members to the optical connector.
In an alternative method, a portion of the cable jacket is removed between the jacket band and the remainder of the cable jacket. The jacket band is pulled back along the axial length of the optical fiber cable away from the terminal end of the fiber and towards the remainder of the cable jacket. The terminal end of the optical fiber is prepared and is coupled to the stub fiber to form a splice between the terminal end of the fiber and the stub fiber. The jacket band is slid toward the splice, wherein at least a portion of the jacket band is disposed within the cable jacket clamp. A protective tube is placed over the jacket band and exposed fiber. A boot is secured over the cable jacket clamp to clamp the cable jacket clamp onto the protective tube and to secure strength members to the optical connector.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description that follows more particularly exemplify these embodiments.
The present invention will be further described with reference to the accompanying drawings, wherein:
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “forward,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention.
The present invention is directed to an optical fiber connector and method of field termination of a jacketed optical fiber cable. In particular, the optical fiber connector of the exemplary embodiments is of compact length and is capable of straightforward field termination. The exemplary connector(s) described herein can be readily installed and utilized for Fiber To The Home (FTTH) and/or Fiber To The X (FTTX) network installations. The exemplary connector(s) can be utilized in installation environments that require ease of use when handling multiple connections, especially where labor costs are more expensive.
According to an exemplary embodiment of the present invention, an optical fiber connector 100 is shown in isometric view in
Optical connector 100 is configured to mate with a receptacle of a corresponding format. For example, as shown in
As shown in
Connector 100 includes a housing 110 having an outer shell configured to be received in an SC receptacle (e.g., an SC coupling, an SC adapter, or an SC socket). As shown in
In this exemplary embodiment, connector 100 can be utilized to terminate a field optical fiber cable 135 (see e.g.,
In one aspect, the backbone 116 (see e.g.,
Backbone 116 includes an opening 112 at a front end to allow for insertion of the collar body 120. Backbone 116 further includes an access opening 117, which can provide access to actuate a mechanical splice device disposed within the connector collar body. In a preferred aspect, as is shown in
In addition, the backbone can include a fiber guide 113 formed in an interior portion therein to provide axial alignment support for the optical fiber cable being terminated. In an exemplary aspect, the fiber guide portion 113 is a funnel-shaped channel or groove that aligns a buffered portion of the optical fiber and guides the fiber toward the mechanical splice device 140 housed in the collar body 120.
The backbone 116 also includes a collar body mount structure 115 configured to receive and secure the collar body 120 within the backbone. In a preferred aspect, collar body mount structure 115 comprises a rigid structure formed in an interior region of backbone 116 having an axial bore therethrough. The axial bore can be of appropriate size to receive and engage raised end structure 128 of collar body 120 (see
Backbone 116 can further include one or more stops 114 formed on an interior portion thereof to provide a boundary for the insertion of the cable jacket 136 of the optical fiber cable 135 being terminated (as explained in more detail below). In addition, backbone 116 includes a clamping portion 119 formed at one an end of the backbone. The clamping portion 119 is configured to clamp onto the cable jacket 136 of the optical fiber cable 135 being terminated in connector 100. In a preferred aspect, clamping portion 119 comprises a collet-type, split body shape that is actuated when the boot is secured to mounting structure 118. The clamping portion 119 can include raised inner surfaces to permit ready clamping of the cable jacket 136. In addition, the clamping portion 119 also can provide a guide structure when inserting fiber cable 135 during the termination process. Thus, boot 180 can be utilized to clamp the fiber strength members 139 and the cable jacket 136. The interaction of the boot 180 and the backbone 116 will be described in greater detail below.
The connector also includes a tube or sheath 195 to be placed over the cable jacket of the optical fiber cable. The tube or sheath can be constructed from a conventional material, such as a plastic (e.g., plasticized PVC, urethanes, silicones, elastomers). As explained in more detail below, during the exemplary termination process, the cable jacket 136 can be slit or removed to leave an exposed portion of the fiber cable. The tube or sheath 195 is adapted to slide over the cable jacket at the slit or removed portion to protect and/or conceal the exposed portion of the fiber. In addition, the tube or sheath 195 can provide additional structural integrity against extraneous forces, such as side-pulls. The tube or sheath 195 is configured to have an axial length sufficient to cover the slit portion of the cable jacket or the exposed portion of the optical fiber. In a preferred aspect, the tube or sheath 195 extends well beyond the end of the attached boot 180 when connected with the backbone 116. In addition, tube or sheath 195 can act as an adapter tube when the optical fiber cable being clamped is of an even smaller diameter.
According to an exemplary embodiment of the present invention, housing 110 and backbone 116 are formed or molded from a polymer material, although metal and other suitably rigid materials can also be utilized. For example, one exemplary material can comprise a fiberglass reinforced polyphenylene sulfide resin. Housing 110 is preferably secured to an outer surface of backbone 116 via snap fit (see e.g., outer engagement surface 111 shown in
As mentioned above, connector 100 further includes a collar body 120 that is disposed within the connector housing and retained by the backbone. According to exemplary embodiments, the collar body 120 is a multi-purpose element that can house a ferrule 132 and optical fiber stub 134 and a mechanical splice device 140. The collar body is configured to have some limited axial movement within backbone 116. For example, the collar body 120 can include a collar or shoulder 125 that can be used as a flange to provide resistance against spring 155 (see
In particular, collar body 120 includes a first end portion 121 having an opening to receive and house a ferrule 132 having an optical fiber stub 134 secured therein. The collar body also includes a second end portion 126 configured to engage with the collar body mount structure 115 of backbone 116. In a preferred aspect, second end portion 126 has a raised end structure 128 that has a sloping shape that is insertable through the bore of the collar body mount structure 115, as is shown in
The collar body 120 also secures the fiber stub and ferrule in place in the connector 100. Ferrule 132 can be formed from a ceramic, glass, plastic, or metal material to support the optical fiber stub 134 inserted and secured therein. In a preferred aspect, ferrule 132 is a ceramic ferrule.
An optical fiber stub 134 is inserted through the ferrule 132, such that a first fiber stub end slightly protrudes from or is coincident or coplanar with the end face of ferrule 132. Preferably, this first fiber stub end is factory polished (e.g., a flat or angle-polish, with or without bevels). A second end of the fiber stub 134 extends part-way into the interior of the connector 100 and is spliced to the fiber portion 138 of an optical fiber cable (such as optical fiber cable 135). Preferably, the second end of fiber stub 134 can be cleaved (flat or angled, with or without bevels).
In one aspect, the second end of fiber stub 134 can be polished in the factory to reduce the sharpness of the edge of the fiber, which can create scrapings (debris) as it is installed in the splice element. For example, an electrical arc, such as one provided by a conventional fusion splicer machine, can be utilized to melt the tip of the fiber and form a rounded end, thereby removing the sharp edges. This electrical arc technique can be used in conjunction with polishing by an abrasive material to better control end face shape while reducing possible distortion of the core. An alternative non-contact method utilizes laser energy to ablate/melt the tip of the fiber.
Fiber stub 134 and fiber portion 138 can comprise standard single mode or multimode optical fiber, such as SMF 28 (available from Corning Inc.). In an alternative embodiment, fiber stub 134 additionally includes a carbon coating disposed on the outer clad of the fiber to further protect the glass-based fiber. In an exemplary aspect, fiber stub 134 is pre-installed and secured (e.g., by epoxy or other adhesive) in ferrule 132, which is disposed in the first end portion 121 of collar body 120. Ferrule 132 is preferably secured within collar body first end portion 121 via an epoxy or other suitable adhesive. Preferably, pre-installation of the fiber stub can be performed in the factory.
Referring back to
For example, commonly owned U.S. Pat. No. 5,159,653, incorporated herein by reference in its entirety, describes an optical fiber splice device (similar to a 3M™ FIBRLOK™ II mechanical fiber optic splice device) that includes a splice element that comprises a sheet of ductile material having a focus hinge that couples two legs, where each of the legs includes a fiber gripping channel (e.g., a V-type (or similar) groove) to optimize clamping forces for conventional glass optical fibers received therein. The ductile material, for example, can be aluminum or anodized aluminum. In addition, a conventional index matching fluid can be preloaded into the V-groove region of the splice element for improved optical connectivity within the splice element. In another aspect, no index matching fluid is utilized.
In this exemplary aspect, the splice element 142 can be configured similar to the splice element from a 3M™ FIBRLOK™ II mechanical fiber optic splice device or a 3M™ FIBRLOK™ 4×4 mechanical fiber optic splice device. Other conventional mechanical splice devices can also be utilized in accordance with alternative aspects of the present invention and are described in U.S. Pat. Nos. 4,824,197; 5,102,212; 5,138,681; 5,155,787; and 7,140,787, each of which is incorporated by reference herein, in their entirety.
Mechanical splice element 142 allows a field technician to splice the second end of fiber stub 134 to a stripped fiber portion 138 of an optical fiber cable 135 at a field installation location. In an exemplary embodiment, utilizing a 3M™ FIBRLOK™ II mechanical fiber optic splice device, splice device 140 can include splice element 142 and an actuating cap 144 (
Splice element 142 is mountable in a mounting device or cradle 124 (partially shown in
The mechanical splice allows a field technician to splice the second end of fiber stub 134 to the fiber portion 138 of an optical fiber cable 135 at a field installation location. The term “splice,” as utilized herein, should not be construed in a limiting sense since splice device 140 can allow removal of a fiber. For example, the element can be “re-opened” after initial actuation, where the splice element housing portion can be configured to allow for the removal of the actuating cap if so desired by a screw driver or similar device. This configuration permits repositioning of the spliced fibers, followed by replacement of the cap to the closed position.
As mentioned above, fiber boot 180 can be utilized for several purposes with optical connector 100. As shown in
In an exemplary aspect, boot 180 is formed from a rigid material. For example, one exemplary material can comprise a fiberglass reinforced polyphenylene sulfide resin or a polyether imide resin, such as an ULTEM material (available from SABIC). In another aspect, the materials used to form the boot 180 and the backbone 116 are the same.
An exemplary fiber cable utilized in this embodiment comprises a 3.0 mm jacketed communication cable, such as a patch cord or drop cable, commercially available from Samsung Cable, Thai-han Cable, and others (all of Korea). As would be understood by one of ordinary skill in the art given the present description, the optical connector of the exemplary embodiments can be configured to terminate the fibers of other types of jacketed cable, including 3.5 mm communication cable, and others.
As mentioned above, the optical fiber connector of the exemplary embodiments is of compact length and is capable of straightforward field termination. An exemplary termination process according to exemplary aspects of the present invention is now described with reference to
As discussed above, the optical fiber connector is partly assembled by inserting the collar body 120, with ferrule 132 secured therein, into the opening 112 of the backbone 116. This step may be performed prior to the field termination process or during the field termination process. As mentioned above, the raised end structure 128 of the collar body is inserted into the bore of collar body mount structure 115. The spring 155 is placed over the second portion of the collar body prior to installation in the backbone and will provide some bias against axial movement after insertion.
For field termination, an optical fiber cable, such as cable 135, is prepared by stripping off a small portion of the cable jacket 136 at the cable end, leaving the remaining coated portion 137, fiber portion 138, and strength members 139 intact. For the exemplary SC-type connector 100 shown in the figures, this small portion of the cable jacket can be about 65 mm or so. In one aspect, a portion of the cable jacket 136 can be slit along its axial length to leave a slit portion of the cable jacket and an intact portion of the cable jacket nearest the terminal end of the fiber cable.
This cable preparation is illustrated in
In an alternative aspect, such as is shown in
After the slitting of or removal of a portion of the cable jacket, the jacket band is pulled back along the axial length of the fiber cable as is shown in
In addition, in an alternative aspect of the invention, the terminal end of the fiber can be placed in a termination tool or platform for the stripping, cleaving, and cleaning operations.
As shown in
The splice device can then be actuated while the fibers are subject to an appropriate end loading force. To actuate the splice device, a user presses downward (with a modest thumb or finger force) onto the cap 144 of the splicing device. Alternatively, connector 100 can be mounted in a termination platform or tool, such as the 8865 AT tool, commercially available from 3M Company. In this manner, a portion of the fiber cable can be clamped by the termination tool during the actuation process. For example,
The cable jacket can then be released at clamping portion 119 or by the clamp on the termination tool, thereby releasing the fiber bow.
As the investigators have determined, when the contact force between the stub fiber and field fiber is too high, fiber mis-alignment can occur, which may lead to optical losses. This contact force can increase when the fiber coating is very stiff or the length of the field fiber is very short. This high force can be alleviated by temporarily removing the cable jacket from the terminal end of the fiber prior to termination to the stub fiber. The above mentioned slitting and cable jacket displacement process exposes a (relatively) long length of the buffer coated fiber at the terminated end. As is shown in
After the jacket band has been disposed at the rear end of the connector, the tube or sheath 195 is moved toward the rear end of the connector to cover the exposed portion 135a of the fiber cable and at least a portion of the jacket band 136b. In addition, at least a portion of the tube or sheath 195 is disposed in the jacket clamp portion 119 of the backbone 116.
The boot 180 (which is previously placed over fiber cable 135) is then pushed axially toward the backbone mounting structure 118 (see
While the above termination processes are described with respect to the exemplary 3.0 mm jacketed optical fiber cable, the termination processes described herein can be utilized with jacketed optical fiber cables of other sizes and shapes. Furthermore, the termination processes described herein can be utilized with optical connectors that connect single or multiple optical fibers. Also, the termination processes described herein can be utilized to form a restoration splice or with optical connectors that do not incorporate a fiber stub. In addition, the termination processes described herein can be utilized with or without a termination tool or platform to hold the optical connector during the termination process.
Thus, the above termination procedure can be accomplished in the field and allow for optimal axial pre-loading of the fiber into the splice device with reduced bow forces as the cable jacket can be displaced from the terminal end of the field fiber. In addition, the use of an axially displaceable cable jacket band allows the installer to organize the fiber and strength members during the final stages of assembly by sliding the cable jacket band towards the end of the field fiber and provides a more robust assembly. The optical connector is re-usable in that the actuating cap can be removed and the above steps can be repeated.
The optical connectors described above can be used in many conventional optical connector applications such as drop cables and/or jumpers. The optical connectors described above can also be utilized for termination (connectorization) of optical fibers for interconnection and cross connection in optical fiber networks inside a fiber distribution unit at an equipment room or a wall mount patch panel, inside pedestals, cross connect cabinets or closures or inside outlets in premises for optical fiber structured cabling applications. The optical connectors described above can also be used in termination of optical fiber in optical equipment. In addition, one or more of the optical connectors described above can be utilized in alternative applications.
As mentioned above, the optical connector of the exemplary embodiments is of compact length and is capable of straightforward field termination. Such exemplary connectors can be readily installed and utilized for FTTP and/or FTTX network installations.
Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US11/64857 | 12/14/2011 | WO | 00 | 6/6/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61429657 | Jan 2011 | US |
