Abstract:
An optical fiber coupling assembly is provided herein for the coupling of at least a pair of fiber cables. A connector is installed to an end of a fiber cable. The connector is then inserted into a through channel of a coupler. A spring-loaded latch inside the through channel is used to force the cores of the fiber cables to be tightly joined together, reducing the power loss of the light signal transmission over the pair of coupled fiber cables. The coupling assembly is structurally simple, has a smaller form factor, and is able to increase installation efficiency and reduce production cost.

Description:
This is a continuation-in-part of U.S. application Ser. No. 11/135,423, now U.S. Pat. No. 7,036,996, filed May 23, 2005. 

   BACKGROUND OF THE INVENTION 
   (a) Technical Field of the Invention 
   The present invention generally relates to optical fibers, and more particularly to a coupling assembly comprising coupler and connectors for tight joining of the cores of fiber cables. 
   (b) Description of the Prior Art 
   The introduction of fiber optics has dramatically changed how telecommunications is conducted. Using lights as carriers and fiber cables to deliver light signals precisely and accurately, fiber optics provides signal transmissions far superior than conventional means and, therefore, relevant industries have emerged around the field of fiber optics. 
   In real-life applications, it is often required to join two fiber cables together using passive devices such as couplers. An ideal coupler should be able to provide low power loss, reliability in terms of frequent connection and disconnection, durability under harsh environment, and easy installation. Currently, a common fiber coupler establishes physical contact between two fiber cables by receiving the connectors installed at the ends of the fiber cables into the through channels inside the coupler. Usually a spring or other similar device inside the coupler exerts pressure on the connectors so that the cores of the fiber cables are in close contact with each other, and light signals could thereby be transmitted from one fiber cable to another. 
   For example, both the U.S. Pat. No. 5,359,688 and Republic of China, Taiwan, Patent No. 302,441 discloses different connector and coupler designs for joining a single pair of fiber cables. The connectors according to these teachings contain multiple components arranged in a complicated structure. Therefore, not only the installation of the connectors becomes troublesome, but also the coupler requires a larger form factor so as to accommodate the more complicated connectors. In user environments where facility space is tight, the bulky couplers would provide only a limited number of cable couplings. 
   U.S. Pat. No. 5,719,977 therefore discloses a design which achieves a coupler having a smaller form factor by utilizing specially-shaped connectors. Compared with conventional connectors and couplers, the design is able to provide an additional pair of fiber cable coupling within a compatible dimension. The space saving of the teaching, however, is compromised by the additional requirement of increased precision in the production of reduced-sized components. For example, the diameter of the connector&#39;s tubular plug is reduced from the conventional 2.5 mm to 1.25 mm, making the manufacturing process much more difficult and, therefore, increasing the production cost dramatically. 
   Accordingly, an improved design is required so as to strike a balance between the requirements for scaling down the component sizes and for reducing operation difficulty and production cost. 
   SUMMARY OF THE INVENTION 
   The primary purpose of the present invention is to provide an assembly for fiber cable coupling, which utilizes structurally simple and easy-to-assembly connectors and coupler. The coupler is able to join fiber cables whose connectors have conventional 2.5 mm tubular plugs within the conventional form factor, thereby achieving the size reduction for the coupler while reducing the production cost of both the coupler and connectors. 
   To achieve the foregoing purpose, the coupling assembly provided by the present invention contains structurally simple connectors and coupler. The coupler is formed by joining two identical body members. A crimp ring fixedly install the connector body to an end of a fiber cable. A tubular plug of the connector body is fit inside a sleeve or through channel of the coupler. A spring-loaded latch exerts pressure on the connector body so that the cores of the fiber cables are tightly joined together, providing effective and lossless light signal transmission over the two fiber cables. The coupling assembly of the present invention is able to provide coupling for an additional pair of fiber cables within the same form factor as conventional couplers. Due to its simplicity, the coupling assembly of the present invention could further reduce production cost and increase installation efficiency. 
   The foregoing object and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
   Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective exploded view showing the coupling assembly according to an embodiment of the present invention. 
       FIG. 2  is a perspective view showing two pairs of fiber cables coupled by the coupling assembly of  FIG. 1 . 
       FIG. 3  is a perspective view showing the interaction of the coupler and the connector of the coupling assembly of  FIG. 1 . 
       FIG. 4  is a sectional view showing a fiber cable is plugged into the coupler of the coupling assembly of  FIG. 1 . 
       FIG. 5  is a sectional view showing another fiber cable is plugged into the coupler of the coupling assembly of  FIG. 4 . 
       FIG. 6  is a perspective view showing a fiber cable is plugged into the coupler of the coupling assembly of  FIG. 1 . 
       FIGS. 7A &amp; 7B  is a perspective view showing a fiber cable is unplugged from the coupler of the coupling assembly of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following descriptions are of exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
   As illustrated in  FIGS. 1 to 3 , an embodiment of the optical fiber coupling assembly according to the present invention mainly contains optical fiber connectors  10  and a coupler  20 . 
   The connector  10  has a tubular body member  11  with a tubular plug  14  at an end (hereinafter, the back end), which has the other end (hereinafter, the front end) threaded through and extended out of a tubular segment  12 . At the back end of the tubular segment  12 , there is an arc indentation (not numbered) on the cylindrical outside wall of the tubular segment  12  in front of said tubular plug  14 . The emerged section of the body member  11  is then threaded through a crimp ring  13  and pierces into the cladding layer (not numbered) and the sheath layer (not numbered) of a fiber cable  30 . The crimp ring  13  is used to fixedly clip the fiber cable  30  and the tubular body  11  together, and to achieve an appropriate tension between the fiber cable  30  and the connector  10 . Please note that the core  31  of the fiber cable  30  is exposed for an appropriate length so that it is extended out of the tubular plug  14  of the body member  11 . The extraneous fiber core  31  outside the tubular plug  14  is cut and removed. The fiber core  31  is then abraded so that its end surface is flush against the tubular plug  14 &#39;s back end. At this point, the installation of the connector  10  to the fiber cable  30  is completed. Please note that, on the cylindrical outside wall of the tubular plug  14  as shown in  FIG. 3 , there is a groove  15  along the axial direction of the connector  10  for preventing the connector  10  from rotation inside the coupler  20 . In contrast to the conventional connectors having springs and other component inside and therefore having higher production cost and fiber cable installation difficulty, the connector  10  of the present invention is significantly simplified and cost-downed. 
   The coupler  20  is assembled by joining a pair of corresponding body members  21 . Each body member  21  has a pair of parallel, circular through channels  23  for receiving the tubular plugs  14  of two fiber cables  30 &#39;s connectors  10 . The through channels  23  of the body members  21  are properly aligned so that, when the body members  21  are attached together, their through channels  23  are joined to form a pair of through ducts (not numbered) from one end of the coupler  20  to the other end. Each of the through channels  23  is configured such that, from a cross-sectional point of view, the through channel  23  is similar to being formed by two semi-circular pieces joined together by a pair of radially aligned connection blocks  22 . At an appropriate location on the circular wall of each through channel  23 , there is a positioning block  24 . The positioning block  24  is configured correspondingly to the groove  15  of the tubular plug  14  so that, when a fiber cable  30  is inserted into the coupler  20 , the positioning block  24  is received by the groove  15  and the connector  10  is prevented from rotating inside the coupler  20  and causing light power loss resulted from the misconnection and inappropriate wearing at the interface of the two connected fiber cables  30 . 
   A tubular segment  27  is positioned inside each of the through ducts and is extended from one through channel  23  to the other. The dimension of the tubular segment  27  is configured such that the tubular plug  14  can be fitted inside perfectly. A C-shaped latch  25  having two parallel hooks  28  and a helix spring  26  positioned between the two hooks  28  are sleeved over an end of the tubular segment  27  via a hole  29  of the latch  25 . Each end of the tubular segment  27 , along with the latch  25  and the spring  26  at that end, is inserted into the back end of a through channel  23  of a body member  21  until the hooks  28  pass over and locks on the connection blocks  22 , causing the spring  26  slightly compressed by the connection blocks  22 . 
   As shown in  FIGS. 4 and 5 , to use the coupling assembly of the present embodiment, the connector  10  of a first fiber cable  30  is inserted into the front end of a through channel  23  of a first body member  21  of the coupler  20  by aligning the positioning block  24  and the groove  15 . As the tubular plug  14  enters the through channel  23 , the hooks  28  are pushed apart and, as the tubular plug  14  is inserted further, the hooks  28  embed into the arc indentation along the outside wall of the tubular segment  12  of the connector  10 , as shown in  FIG. 6 . The tubular plug  14  can go all the way through the through channel  23  and extends into a second body member  21  of the coupler  20 . When a second fiber cable  30  is inserted into the corresponding through channel  23  of the second body member  21 , the second fiber cable  30  will force the first fiber cable  30  backward and compress the spring  26  of the first body member  21 . Correspondingly, the second cable  30  and the spring  26  of the second body member  21  will suffer an equal amount of counterforce. As the two body members  21  are configured identically, when the resilient force of the two springs  26  reach an equilibrium state, the cores  31  of the first and second fiber cables  30  would be tightly joined together. 
   To unplug a fiber cable  30 , the tubular segment  12  is twisted until the hooks  28  are pushed apart as they are forced out of the arc indentation as shown in  FIGS. 7A &amp; 7B . Then, the fiber cable  30  can be pulled out of the coupler  20  manually or ejected by the resilient force of the spring  26 . 
   Due to the simplified structure of the connectors  10  and the coupler  20 , the present embodiment is able to provide coupling for an additional pair of fiber cables  30  within the same form factor as the conventional couplers. In addition, the tubular plug  14  of the body member  11  has an ordinary diameter and, therefore, requires no special treatment and parts and hence less production cost. Furthermore, the reduced number of components and convenience of operation also further contribute to enhanced installation efficiency. 
   It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
   While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.