High density fiber optic connector with individual fiber removal

[0002] There is a need for high capacity and high density optical fiber connectors that facilitate maintenance of a single optical fiber assembly without disrupting communications through of all the other optical fiber assemblies. For example, there are requests for connector systems with hundreds of fiber assemblies to fit within eight inches square of space on a panel, the system being composed of separate modules of thirty-two fibers each. Such assembly must allow a single fiber assembly to be removed for cleaning or other maintenance and repair without disrupting communications through the other hundreds of optical fibers. A system which was very compact but still allowed individual fiber maintenance would be of value.

[0003] In accordance with one embodiment of the present invention, applicant provides an optical fiber connector system of a type that has individual alignment sleeves and loading springs for each pair of coupled optical fiber assemblies for efficient light coupling. The system organizes the fibers and cables extending from each of a plurality of modules to enable easy access to an individual optical fiber assembly. Each rear module includes a module body and a backshell extending rearwardly from the module body. Optical fiber cables that each includes a plurality of optical fibers, have jackets with jacket front ends lying within the backshell. Free optical fiber portions extending forward at the jackets and within the front of the backshell, extend into passages in the rear module body. Each backshell has a rectangular front end and each backshell has a pair of fastener-receiving backshell passages at opposite corners. A pair of backshell fasteners extends through each backshell passage, each fastener having a front end that is detachably connected to the rear body of the module.

[0004] The modules are arranged in a plurality of rows and columns in corresponding ports of a main rear shell. Each port receives one of the module bodies and has a pair of internal flanges for receiving jackscrews.

[0005] Jackscrews that fasten each module body to the rear shell, are aligned with the backshell fasteners. The backshell fasteners have wrench-receiving passages extending along their axes, so a wrench can pass through a backshell fastener to turn a jackscrew.

[0006] A cable holder has a rear end that lies within the backshell and that holds the front ends of the optical cables where the individual cables are unwrapped from the cable jackets. The cable holder has a post that extends forwardly and is coupled to the module housing to fix the positions of the cable front ends. This facilitates removal of an individual optical fiber assembly from a passage of the module housing.

[0007] The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.

[0008] FIG. 1 is a front isometric view of an optical fiber connector system of the present invention.

[0009] FIG. 2 is a partially exploded front isometric view of the connector system of FIG. 1, showing the front and rear connectors, showing an individual alignment sleeve frame detached from the front connector, and showing a rear module detached from the rear main shell.

[0010] FIG. 3 is a front isometric view of the main rear shell of the rear connector of FIG. 2.

[0011] FIG. 4 is an exploded front isometric view of one the rear modules of the rear connector of FIG. 2, with the backshell slid rearwardly from its fully installed position.

[0012] FIG. 5 is an exploded front isometric view of the alignment sleeve frame and sleeves of the connector system FIG. 2.

[0013] FIG. 6 is a partial sectional view of the connectors of FIG. 2 shown fully mated.

[0014] FIG. 7 is a sectional view showing a corner region of the rear module of FIG. 4, and also showing its connection to the main rear shell of FIG. 3

[0015] FIG. 8 is an exploded front isometric view of the cable holder of FIG. 4.

[0016] FIG. 1 shows an optical fiber connector system 10 which has a small profile in lateral L and vertical V directions, such as eight inches by eight inches, and yet which efficiently couples three hundred twenty optical fibers. Rear optical fiber cables 82 are shown but front optical fiber cable are not shown. The system includes a receptacle or front connector 12 mounted on a drawer or rack plate 16 and a plug or rear conneotor 14 mounted on a panel 20. With a drawer lock 22 fixing the drawer, a handle 24 can be turned to turn a main jackscrew 26 that draws the connectors 12, 14 close together. As the connectors move together, the tips of optical fibers of the two connectors move together until the tips abut to couple the optical fibers (if the tips do not already abut).

[0017] FIG. 2 shows the two connectors 12, 14. The front connector 12 includes a front shell and body apparatus 32 that includes ten modules regions 34. Each module region includes thirty-two passages 36 that each receives an optical fiber coupling assembly. Ten sleeve-holding frames 40 each holds thirty-two alignment sleeves, and is installed on the front shell and body apparatus 32. The rear connector 14 includes a main rear shell 50 that has a plurality of module-receiving ports 52. Each port 52 receives part of, and preferably most of, the module body 54 of a rear module 60. The rear connector includes ten module regions 56 occupied by ten rear modules 60 arranged in three vertically V extending columns 61-63 and a plurality of lateral L extending rows. There are four modules in each side column 61, 63 and two modules in the middle column 62. FIG. 3 shows details of the main rear shell SO and of its ports 52.

[0018] FIG. 4 shows that the rear module body 54 includes a front plate 70 and a back plate 72. The plates form laterally L extending rows and vertically V extending columns, of passages 74. Each passage holds an optical fiber coupling assembly 76. Thirty-two optical fibers 80 extend rearwardly from the thirty-two passages. It is noted that each optical fiber 80 actually includes a thin optical fiber element with a cladding around it and usually with a protective covering. The optical fibers emerge from four optical cables 82 that each holds eight optical fibers. A backshell 84 surrounds the front ends 90 of the four optical cables and surrounds free optical fiber portions 92 that are not surrounded by the jackets 96 of the cables and that lie behind the module body. The free optical fiber portions 92 extend from the cable front ends 90 to the rear module body 54. The length of the free fiber portions 92 is preferably at least half the length of the backshell 84. At the rear end of the backshell, a cable bend relief 94 that is attached to the backshell, provides strain relief for the four optical cables 82. The backshell longitudinal length is preferably more than four time the module body length.

[0019] FIG. 6 shows a pair of optical fiber coupling assemblies 100, 102 that lie in passages 74, 106 of the rear and front connectors. Each rear coupling assembly 100 includes an optical fiber 80 with the front end 110 of the fiber extending through a ferrule 112. The front tip of the fiber front end 110 abuts the front tip of the fiber of the front optical fiber coupling assembly 102 of the front connector. Ceramic alignment sleeves 114 precisely align the two ferrules, while a spring 116 of the rear connector urges the fiber tips to firmly abut one another. The alignment sleeves are held in the sleeve frame 40 which includes two sleeve frame plates 40A, 40B.

[0020] An alignment post 120 is fastened by a locking pin 122 to the front connector shell apparatus 32. A rear portion of the post projects into an alignment sleeve member 124 in the rear module body 54. The body 54 lies one of the ports 52 of the main rear shell 50.

[0021] An individual rear optical fiber coupling assembly 100 can be removed by inserting a tool through the passage 74 to expand a retaining clip 130. Such tool is in the form of a cylinder with a slot along its length to receive the optical fiber. The optical fiber coupling assembly 100 is then removed by merely pulling rearwardly on the optical fiber 80 while the tool is in place.

[0022] As shown in FIG. 3, the main rear shell 50 has a pair of internal flange parts 140 projecting into each of its ports 52. Each internal flange part has a threaded hole 144. FIG. 4 shows that each rear module 60 includes a pair jackscrews 150 with threaded front ends that can screw into one of the threaded holes of the main rear shell to hold the rear module body 54 securely in a corresponding main rear shell port. The jackscrew threads can be bayonet type threads.

[0023] FIG. 7 shows one of the jackscrews 150 with its threaded front end 152 screwed into a threaded hole 144 of an internal flange part 140 that lies +in a port 52 of the main rear shell 50. The module body 54 has a cutout 153 that receives the internal flange part 140. The jackscrew has an external flange 154 forming a forwardly-facing shoulder 156 that abuts a corresponding shoulder of the backplate 72 of the rear module body 54. The backplate 72 presses the front plate 70 against the internal flange 140. The jackscrew has a wrench-engaging rear end 160 for turning the jackscrew to loosen it or tighten it. The particular wrench-engaging end 160 includes a hexagonal cavity, but can include a hexagonal outside or other wrench-engagable shape. The backshell 84 has a fastener-receiving passage 162 that is aligned with the jackscrew 150.

[0024] FIG. 4 shows that the backshell 84 has a largely rectangular front end 170 and a largely circular rear end 171, and that the backshell has a pair of backshell passages 162 at its opposite corners and extending along much of its length. A pair of backshell fasteners 172 lie in the backshell passages 162 and serve to hold the backshell front end 170 against the rear module body 54. Each backshell fastener 172 has a front end 174 that is threaded. Each backshell fastener has a rear end 176 that has a noncircular surface such as a slot for turning by a screwdriver.

[0025] Referring again to FIG. 7, it can be seen that the rear module includes a coupling sleeve 180 with an externally threaded front end 182 and an internally threaded rear end 184. The sleeve 180 may be considered part of the rear module body. The sleeve front end 182 is threadably engaged with a threaded hole 190 in the backplate 72 of the rear module body. The sleeve rear end 184 is threadably engaged with the threaded end 174 of the backshell fastener 172. The backshell fastener has a wrench-receiving passage 192 that can receive a wrench indicated at 194, for turning the rear end 160 of the jackscrew. The jackscrew 150 and backshell fastener 172 are aligned, preferably with their axes 198 aligned in a longitudinal M direction. It is possible to use a very short backscrew whose rear end lies forward of the backshell fastener front end instead of within it.

[0026] If it is desired to remove an entire rear module 60, this can be accomplished using the wrench 194 to turn the jackscrew 150 so as to move the rear module body 54 rearwardly. In practice, each of the two jackscrews that hold the module body in a port of the main rear shell 50, is unscrewed by perhaps one-half turn at a time to move the rear module rearwardly with minimum tilting that could damage the thirty-two optical coupling assemblies lying in passages of the rear module body. The backshell 84 with the thirty-two optical fibers will all be removed as a unit. FIG. 2 shows one of the rear modules 60 removed so another rear module can be substituted for it.

[0027] In many cases, it is desirable to remove a single optical fiber coupling assembly 100 (FIG. 6). This may occur, for example, if less than the usual percent of light is being transmitted between a pair of front and rear optical fiber coupling assemblies. By removing only a single coupling assembly, applicant needs to switch only the limited number of communication channels carried through one optical fiber coupling assembly, to another coupling assembly that is providing as a spare. If an entire module had to be removed every time a defect was detected in one of the thirty-two optical fiber coupling assemblies, then thirty-two times as many channels would have to be switched.

[0028] In order to remove a single optical fiber coupling assembly 100, applicant first removes the backshell 84 (FIG. 7). Applicant accomplishes this by unscrewing the two backshell fasteners 172 from the corresponding coupling sleeve rear ends 184. This results in a configuration such as shown in FIG. 4, where the free portions 92 of the individual optical fibers 80 are accessible. As discussed above, a technician inserts a tool within the retention clip 130 (FIG. 6) and pulls on the optical fiber 80 to remove it from the module body. In many cases, a poor optical fiber connection can be returned to an initial high level by cleaning the tips of the fibers and ferrules. The tip of the removed optical fiber is readily accessible for cleaning. The tip of the front fiber can be cleaned by a special tool that is moved along the corresponding rear module body passage 74 and against the ferrule and optical fiber tip of the front optical fiber assembly 102. During all of this time, the thirty-one other optical coupling assemblies 100 in the module continue to function.

[0029] FIG. 4 shows that the four optical cables 82 are held and connected together by a cable holder 200. The cable holder has a post 202 that extends forwardly and that has a front end threadably engaged with the rear module body 54. FIG. 6 shows the front end 204 of the cable holder post threadably engaged with an internally threaded rear end 206 of the alignment sleeve 124. The post 202 of FIG. 4 fixes the distance of the cable front ends 90 (FIG. 4), from the module body 54 to provide a neat arrangement of the optical fibers free portions 92. This facilitates access to a selected one of the thirty-two optical fibers 80 and the corresponding ferrules for removal and cleaning. The cable holder transfers rearward forces applied to cable jackets, directly to the module body. The cable holder is preferably not fixed to the backshell and lies completely within the backshell. FIG. 8 shows that the cable holder 200 includes a crimp section 210 that includes four crimp sleeves 212. The jacket of each of the four optical cables is wrapped backward around a front end 214 of each sleeve, a crimp ring 216 is placed around the jacket and sleeve front end 214, and the crimp ring 216 is crimped to securely hold to the jacket of each optical cable. The four crimp sleeves 212 lie in a positioner 220 that has a hole that receives the rear end 222 of the post 202. A removable strap (not shown) is wrapped around the four sleeves to hold them in place.

[0030] Thus, the invention provides an optical fiber connector system with front and rear connectors that each has a plurality of module regions for holding multiple optical fiber coupling devices. The rear connector includes a rear main shell with a plurality of module receiving ports that each forms part of one of the module regions. A plurality of rear modules each has a rear module body that fits into one of the ports of the main rear shell. The ports of the main rear shell are arranged in a plurality of rows and columns, with a plurality of ports in each row and each column. The walls of each port include a pair of internal flange parts having threaded holes. Each rear module includes a pair of jackscrews that each has a threaded front end that threadably engages one of the flange parts. A backshell extends behind each rear module body to enclose the optical fiber cable or cables and the free optical fiber portions that extend from front ends of the cables where the jackets have been stripped away. Each backshell has a pair of backshell passages that each receives a backshell fastener that fastens to the rear module body. Each backshell fastener is aligned with one of the jackscrews, to reduce the amount of space occupied by both of them, to provide more space for the multiple optical fiber coupling assemblies. Each backshell fastener has a wrench-receiving passage extending along its length, through which a wrench can be inserted to loosen a jackscrew without requiring the backshell to be removed (which could result in damage to the optical fibers during jackscrew turning). A cable holder which lies primarily within the backshell, has a rear end attached to the optical fiber cables and a front end that is fixed to the module body. As a result, opposite ends of the free portions of the optical fibers are fixed to provide a neat arrangement of multiple optical fibers that facilitates removal and replacement of one optical fiber.

[0031] Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.