Fiber optic connection system

Abstract: The present invention is a fiber optic connection system including a fiber optic plug adapted to mate and lock with a fiber optic connector. The plug includes a housing and mated insert that cooperate to position and secure the plug pre-assemblies with respect to the plug and to structurally affix the cable strengthener to the plug.

Description: BACKGROUND OF THE INVENTION The present invention relates generally to a fiber optic connection system and, more particularly, to a fiber optic plug wherein a housing and mating insert cooperate to secure the fiber optic cable and spring-biased ferrule holders with respect to the plug. Fiber optic transmission of information is now virtually commonplace. Its continued growth demands the development of inexpensive, readily manufactured and quickly replacable connection systems. One such connection system is shown in U.S. Patent No. 5,828,804. SUMMARY OF THE INVENTION In principal aspect, the present invention is a fiber optic connection system including a fiber optic plug adapted to mate and lock with a fiber optic connector. As used herein, the term "connector" means (i) a socket whereby two fiber optic cables are coupled together and (ii) an interface housing, such as a transceiver, whereby a fiber optic cable is coupled to a piece of hardware. The plug includes a housing, a pair of spring-biased ferrule holders and an insert. The housing has curved or arcuate side walls that partially define two passageways. The spring-biased ferrule holders reside within the passageways. Each spring-biased ferrule holder has a sleeve that surrounds the ferrule of the ferrule holder. The side walls of the housing terminate a predetermined distance from the front housing end and thus define a recess in each of the passageways, exposing the two sleeves that are colour-coded and visually accessible through the recesses to provide a means for the identification of the type of fibers being used. The housing and insert snap-lock together and cooperatively define a mechanism to position and maintain the spring-biased ferrule holders. That is, the housing and insert cooperatively secure the ferrule holders with respect to the plug. The housing and insert further cooperate to secure the fiber optic cable with respect to the plug for proper loading, i . e ., the strengthener of the cable (such as aramid yarn) is secured to the plug. It is thus an object of the present invention to provide a new and improved fiber optic connection system. Another object is an inexpensive, readily produced connection system for fiber optic cable. Still another object is a fiber optic connection wherein the plug and connector interlocked to provide connection stability and to substantially avoid connection "play." Yet another object of the present invention is fiber optic plug including a housing and insert snap-locked thereto to substantially facilitate assembly and repair. It is also an object to provide a plug for a fiber optic cable connection system, wherein a housing and mated insert cooperatively secure the plug pre-assemblies and strengthener of the cable to the plug. These and other features, objects and advantages of the present invention are set forth or apparent in the following detailed description. BRIEF DESCRIPTION OF THE DRAWING Various preferred embodiments of the present invention are described herein with reference to the drawing herein: FIGURE 1 is a top perspective, partial cut-away view of a first preferred embodiment of the present invention; FIGURE 2 is an exploded perspective view of the fiber optic plug shown in FIGURE 1; FIGURE 3 is an enlarged, partial cross-sectional view of the fiber optic plug shown in FIGURE 2; FIGURE 4 is a bottom perspective view of the fiber optic plug shown in FIGURE 2; and FIGURE 5 is an exploded perspective view of a second preferred embodiment of the fiber optic plug. DETAILED DESCRIPTION OF VARIOUS PREFERRED EMBODIMENTS A first preferred embodiment of the present invention is shown in FIGURES 1 - 4 as a fiber optic connection system, generally designated 10. The system 10 operatively couples first and second fiber optic cables 12, 14 in an interlocked state. The cable 12 includes side-by-side optical fibers 16, 18, and a cable strengthener, generally designated 20 and typically an aramid yarn. In this preferred embodiment, the optical fibers 16, 18 are individually wrapped with strengthening elements 22, 24, respectively, shown in FIGURE 1 as a solid strand jacket and in FIGURES 3 and 5 as separated loose strands. The second cable 14 similarly includes fiber elements 26, 28 and strengthening elements 30, 32. The system 10 includes a fiber optic plug 34, structurally affixed or secured to the cable strengthener 20 and, more particularly, the strengthening elements 22, 24, and a fiber optic jack 36 structurally affixed to the strengthening elements 30, 32. The socket 36 receives the plug 34 in the interlocked state to selectively couple the bare glass fibers of the optical fibers 16, 18 to the bare glass fibers of the fiber elements 26, 28, respectively, as is well known in the art. The plug 34 includes a housing 38, first and second spring-biased ferrule holders, generally designated 40, 42 in FIGURE 2, and an insert 44, assembled as shown. The housing 38 is generally rectangular and has a front housing end 46 and a rear housing end 48. The socket 36 receives at the front housing end 46; the insert 44 is received at the rear housing end 48. The housing 38 includes a substantially planar top wall 50, a substantially planar bottom wall 52, and substantially arcuate side walls 54, 56. As best shown in FIGURES 2 and 3, the side walls 54, 56 terminate a predetermined distance from the front housing end 46. As such, the housing 38 provides first and second plug stabilizing surfaces 58, 60, defined by the terminating edges of the side walls 54, 56, respectively, and first and second side recesses 62, 64. The housing 38 also includes an interior, central dividing wall 66, extending vertically from the top wall 50 to the bottom wall 52. The dividing wall 66 extends longitudinally from the front housing end 46 to a point between the rear housing end 48 and the plug stabilizing surfaces 58, 60. An upper portion 68 of the dividing wall 66, adjacent the top wall 50, extends to the rear housing end 48. The dividing wall 66 and the upper portion thereof 68 have arcuate side surfaces 70, 72, and 74, 76, respectively, substantially matching the curvature of the side walls 54, 56. Portions of the top and bottom walls 50, 52 form similar interior curves, such that the housing 38 defines side-by-side cylindrical housing passageways 78, 80. The housing 38 further includes thin, substantially annular flanges 82, 84, extending circumferentially within the cylindrical passageways 78, 80, in the region between the housing front end 46 and the plug stabilizing surfaces 58, 60. The top wall 50 defines a pair of opposed snap openings 86, 88 near the rear end 48 of the housing 38. The bottom wall 52 defines a third central snap opening 90. In this preferred embodiment, the housing 38 includes a conventional latch 90, extending from the front housing end 46 along the top wall 50. Each of the spring-biased ferrule holders 40, 42 is a conventional spring-biased assembly. Each assembly 32, 34 includes ceramic ferrule 92, ferrule holder 94, spring 96, backbone 98 and plastic sleeve 100. The sleeve 100 receives and is ultrasonically welded to the backbone 98. The sleeve 100 is centrally located and defines a radially extending front face 102 of the spring-biased ferrule holde 40, 42; the backbone 98 defines a radially extending rear face 104 of the spring-biased ferrule holder 40, 42. The bare glass fibers are secured, in a conventional fashion, to the forwardly extending ceramic ferrules 92. The spring-biased ferrule holders 40, 42 reside within and pass through the passageways 78, 80, respectively. The front face 102 engages and stops against one of the annular flanges 82, 84 therein, with the ceramic ferrule 92 extending beyond the front housing end 46, in a conventional manner. The side windows 62, 64 provide visual access into the housing passageways 78, 80, respectively, and expose the sleeve 100 of each spring-biased ferrule holder 40, 42. The sleeve 100 is conventionally color-coded, with beige representing multi-mode and blue representing single-mode. The color thereof can be readily seen through the side recesses 62, 64, thereby facilitating identification and replacement. The front housing end 46 defines a predetermined corner pattern, generally designated 106. This corner pattern 106 matches the corner pattern of prior connectors distributed by the assignee, whereby the plug 34 is compatible therewith. The insert 44 snap-locks into the housing 38, driving the plug pre-assemblies 40, 42 into abutment with the annular flanges 82, 84 and securing the strengthening elements 22, 24 to the plug 34. More particularly, the insert 44 includes first and second outwardly opening, substantially C-shaped sections 108, 110, which define first and second insert passageways 112, 114, respectively. In an assembled plug state, the housing passageways 78, 80 and the insert passageways 112, 114 substantially axially align. The diameter of the insert passageways 112, 114 is less than the diameter of the housing passageways 78, 80, and the insert 44 engages the dividing wall 66 and the two rear faces 104 in the assembled plug state. As such, the spring-biased ferrule holders 40, 42 are locked with respect to the housing 38. The insert 44 includes first and second, opposed upper snap projections 116, 118, and a central lower snap projection 120. In the assembled plug state, the projections 116, 118, 120 engage and lock into the snap openings 86, 88, 90 of the housing 38. The insert 44 further includes a central, upwardly open channel 122 to receive the upper extension 68 of the dividing wall 66. This overall configuration facilitates assembly of the connection system 10, allowing the insert 44 to be quickly oriented with respect to the housing 38. The fibers 16, 18 and strengthening elements 22, 24 reside within the insert passageways 112, 114 in the assembled plug state. The open outer sides of the passageways 112, 114 facilitate assembly and replacement. The fiber optic socket 36 has front and rear socket ends 122, 124. The socket 36 receives the plug 34 through front socket end 122 and the cable 14 through the socket rear end 124. The front end 122 thereof has an inner configuration substantially corresponding to the front housing end 46. In a conventional fashion, the latch 90 snap-locks to the socket 36 in the interlocked state. The socket 36 includes first and second side offsets 126, 128 extending rearwardly from the front socket end 122 to provide first and second socket stabilizing surfaces 130, 132, respectively. In the interlocked state of the connection system 10, the plug stabilizing surfaces 58, 60 engage and abut the socket stabilizing surfaces 130, 132, respectively. This solid contact between four surfaces 58, 60, 130, 132 substantially enhances and stabilizes the interconnection between the fiber optic plug 34 and socket 36. Another preferred embodiment of the present invention is shown in FIGURE 5. This embodiment is used with fiber optic cable wherein the optical fibers 16, 18 are wrapped with a single strengthening element 20. To maintain proper loading, the strengthening element 20 is affixed to the insert 44, as opposed to the spring-biased ferrule holders 40, 42. In this preferred embodiment, the insert 44 includes a rearwardly extending, substantially cylindrical boss 134. The boss 134 is centrally located, substantially interposed the first and second insert passageways 112, 114, and defines two, substantially opposed fiber slots 136, 138, extending therethrough. The fibers 16, 18 extend through the first and second insert passageways 112, 114 and the fiber slots 136, 138, terminated at the ferrules 92 in a conventional fashion. In each of the preferred embodiments, the fiber optic cable 12 is affixed to the plug 34 for proper loading, i.e., substantially avoiding strain on the optical fibers 16, 18. The housing 38 and the insert 44 cooperate to define interconnection means, generally designated 140, for (i) positioning and securing the spring-biased ferrule holders 40, 42 with respect to the plug 34, and (ii) structurally affixing or securing the strengthener 20 to the plug 34. In the preferred embodiment described immediately above, the interconnection means 140 includes first crimp means, generally designated 142, for securing the single strengthening element 20 to the insert 44 or, more particularly, the boss 134 thereof. In the first preferred embodiment, the interconnection means 140 includes second crimp means, generally designated 144, for securing the strengthening elements 22, 24 to the plug pre-assemblies 40, 42 or, more particularly, the backbones 98 thereof. The first and second crimp means 142, 144 include conventional fiber optic crimping elements 146. To further reduce strain upon the cable 12, the connection system 10 includes a conventional strain relief boot 148. The boot 148 is snap-locked to the insert 44, as best shown in FIGURES 2 and 5. Various preferred embodiments of the present invention have been described herein. It is to be understood that modifications and changes can be made without departing from the scope of the present invention, as defined by the following claims.

Claims: Fiber optic connection system (10) comprising a fiber optic cable (12) having a pair of optical fibers (16, 18); a fiber optic plug (34), receiving the fiber optic cable (12) and including a housing (38), first and second spring-biased ferrule holders (40, 42) and an insert (44), the first and second spring-biased ferrule holders (40, 42) having front and rear surfaces (102, 104); the housing (38) having front and rear housing ends (46, 48), top and bottom walls (50, 52) and substantially arcuate side walls (54, 56), the top, bottom and arcuate side walls defining passageways (78, 80) extending from the front housing end (46) in a substantially side-by-side relationship; the first and second spring-biased ferrule holders (40, 42) sliding in the passageways (78, 80), respectively, and extending beyond the front housing end (46) in an assembled plug state; and the insert (44) at least partially encompassing the optical fibers (16, 18) and being snap-locked to the housing (38) through the rear housing end (48); and a fiber optic socket (36) to receive the fiber optic plug (34) in an interlocked state, the fiber optic plug snap-locking to the fiber optic jack (36); the housing (38) and the insert (44) cooperatively defining interconnection means for positioning the first and second spring-biased ferrule holders (40, 42) with respect to the fiber optic plug (34) and for affixing first cable strengthener (20) to fiber optic plug (34), characterized in that the first and second spring-biased ferrule holders (40, 42) have first and second sleeves (100), respectively, that surround the ferrules (92) of the spring-biased ferrule holders (40, 42), and the substantially arcuate side walls (54, 56) terminate a predetermined distance from the front housing end (46) to define first and second recesses (62, 64) into the first and second passageways (78, 80), exposing the first and second sleeves (100) that are colour-coded and visually accessible through the recesses (62, 64) to provide a means for the identification of the type of fibers being used. Fiber optic connection system as claimed in claim 1 wherein the interconnection means includes first and second flanges (82, 84) within the first and second passageways (78, 80) to engage the front assembly surface (102) of said first and second spring-biased ferrule holders (40, 42), respectively, and the insert (44) engaging the rear surface of the first and second spring-biased ferrule holders (40, 42), thereby securing the first and second spring-biased ferrule holders. Fiber optic connection system as claimed in claim 2 wherein the interconnection means further includes first crimp means (142) for structurally securing a first cable strengthener (20) to the insert (44). Fiber optic connection system as claimed in claim 2 wherein the first cable strengthener (20) includes a pair of strengthening elements (22, 24) associated with the pair of optical fibers (16, 18), respectively, the interconnection means further including second crimp means (144) for structurally securing the pair of strengthening elements (22, 24) to the first and second spring-biased ferrule holders (40, 42), respectively. Fiber optic connection system as claimed in claim 1 wherein the first and second recesses (62, 64) provide first and second plug stabilizing surfaces (58, 60), respectively, to engage and abut the fiber optic socket (36), whereby connection stability is enhanced.

Inventors: CONNELLY JOHN M, MARRS SAMUEL M, RADEK JEFFRY J, CONNELLY, JOHN M., MARRS, SAMUEL M., RADEK, JEFFRY J.
Applicants: PANDUIT CORP, PANDUIT CORPORATION
Application year: 2001
Main classification: G02B6
IPC codes: G02B6