Connector for connecting an optical fiber cable

Abstract: A cable side connector for connecting an optical fiber cable, which is partially usable as of both full lock type and friction type and does not cause a variation in optical coupling in either case, includes a housing 10 and a fixing member 20 which is securely accommodated in the housing 10. The fixing member 20 is formed with locking arms 25 which engage engaging projections of a module side connector when the cable side connector is coupled with the module side connector or the housing is formed with a friction lock projection. This connector can be used as of full lock type and of friction type only by replacing the fixing member. Further, since the housing 10 is used commonly for the both types, displacement of the ferrule which is required to have accuracy can be prevented.

Description: DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a connector for connecting an optical fiber cable and a photoelectric device or for connecting optical fiber cables. When, for example, a photoelectric device and an optical fiber cable are connected, it is a general practice that a module side connector is mounted on the photoelectric device and a cable side connector is mounted on the optical fiber cable. The photoelectric device and the optical fiber cable are connected by coupling these connectors. In this case, there are two types of locking mechanisms for locking the coupled state of the connectors: friction lock type and full lock type. The friction lock type is such that a projection is, for example, formed on the outer surface of the cable side connector. When the cable side connector is fitted and coupled with the module side connector, this projection presses the module side connector and the coupled state of these connectors is readily secured with a frictional force. On the other hand, the full lock type is such that the cable side connector is provided, for example, with a locking claw and the module side connector is formed with an engaging portion engageable with the locking claw. The coupled state of the connectors is stronly secured by engagement of the locking claw with the engaging portion. US-A-5,107,536 concerns an optical fiber terminus in which front and rear connector bodies are provided, each having a bore with a counterbore being formed in the rearward end of said front connector body. A sleeve is provided with a tapered surface and slots through it so that one end portion of the sleeve can flex transversely. A taper is formed in the counterbore, matching the taper of the sleeve. The sleeve is positioned in the counterbore and an optical fiber is extended through sleeve and the bores. The rear connector body is advanced a predetermined distance into the counterbore, which it engages with a press fit, so that the sleeve is biased forwardly to cause a reaction between the tapered surfaces, thereby compressing one end portion of the sleeve inwardly to grip and retain the optical fiber. EP-A-0 125 398 concerns a fiber optic connector for optically coupling a pair of fiber optic cables or a single fiber optic cable and a light source or detector. A terminal member includes a pair or identical matching halves defining a through hole extending axially therethrough. The through hole has a fist portion extending through a mating end of the terminal member and sized to snugly receive a length of the fiber core stripped of the outer coating and properly positioning the core with respect to the mating end of the terminal member. The through hole has s second portion extending through a rear end of the terminal member and sized for receiving the outer coating of the fiber optic cable. Projections are to prevent lengthwise movement of the fiber optic cable relative to the terminal member. A ferrule member is positionable over the rear end of the terminal member for biasing the projections into clamping engagement with the outer coating of the fiber optic cable. EP-A- 0 177 937 relates to an optical fibre connector comprising: an internal member including a block having a hole to receive a sheath portion on an end of an optical fiber cord and an optical fiber exposed therefrom, and cantilevers provided on the side walls of the block to extend along the walls, which cantilevers respectively have projections protruding inward as well as projections which protrude outward when no force is applied thereon. The optical fiber connector comprises further an external member including an opening through which said optical fiber cord is inserted, and openings or recesses which engage with the projections on the cantilevers of the internal member on the side wall thereof to be fit into the block of the internal member axially and slidably. The internal member is inserted into the external member gradually, the projections project therethrough to thereby prevent said external member from receding therefrom. US-A-4,779,949 relates to a connector for optical fiber used for optical communication parts, especially to a plug of the connector, comprising an inner tube into which an endportion of an optical fiber cord, whose cover is peeled off, is inserted and which is formed with axial slittings; and an outer tube being fitted onto the inner tube and made of a solid material, the inner tube being reduced in diameter at the portion having the slittings, thereby fixing the optical fiber thereto. One of the drawbacks and shortcomings of the prior art resides in the difficulties when using none compatible joining members for connecting an optical fiber cable and a photoelectric device or for connecting optical fiber cables. In view of the above problem, it is an object of the invention to provide a connector for connecting an optical fiber cable which is partially usable as of both full lock type and friction type and does not cause a variation in optical coupling in either case. This object is achieved by a connector having the features of claim 1. According to the invention, since the locking arms are mounted on the fixing member, the connector can also be used as of friction type by replacing the fixing member with the one without the optional locking arms. At this time, as the housing to be coupled with the mating connector is commonly used for the both types, the ferrule is not displaced relative to the mating connector in either case where the connector is used as of full lock type or of friction type. Preferred embodiments as well as a connector system are defined in the subclaims. Preferably, when the optical fiber cable having the exposed leading end where the insulation was peel off is inserted into the insertion hole formed in the holding plate of the fixing member, the core and the coating of the optical fiber cable are retained by the retainers, respectively. When this fixing member is fitted in the housing, the retainers are smoothly introduced to the pressing portion through the receptacle because of the presence of the tapered face formed at the stepped portion of the housing. The retainers are pressed inward in the pressing portion, and thereby the projections formed at the leading ends of the retainers come into pressing contact with the core and the coating of the optical fiber cable. As a result, the optical fiber cable is secured by the fixing member and the fixing member is secured in the housing. At this stage, the locking portions of the fixing member are engaged with the engaging portions of the housing, thereby preventing the fixing member from getting out of the housing. When the thus assembled connector is coupled with the mating connector, the locking claws of the locking arms mounted on the fixing member are engaged with the engaging portions of the mating connector, thereby locking the coupling of the connectors. Further, when the connector is coupled with the mating connector, the locking claws formed at the leading ends of the second arms come into contact with the engaging portions of the mating connector and are moved forward while undergoing deflection. The locking claws are returned to their original shape after moving over the engaging portions and are engaged therewith, with the result that the coupling of the connectors is locked. The locked state is released as follows. When the rear ends of the first arms are pressed inward, the leading ends of the second arms move wider open, thereby releasing engagement of the locking claws with the engaging portions of the mating connector. When the optical fiber cable having an exposed leading end is inserted through the insertion hole of the holding plate, the end face of the insulation of the optical fiber cable comes into contact with the contact portion of the retainer for retaining the core of the optical fiber cable. As a result, the optical fiber cable is positioned relative to the fixing member. These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings in which: FIG. 1 is an exploded perspective view of a cable side connector of one embodiment according to the invention, FIG. 2 is a section along line V-V of FIG. 1, FIG. 3 is a section along line W-W of FIG. 1, FIG. 4 is a section along line X-X of FIG. 1, FIG. 5 is a section along line Y-Y of FIG. 1, FIG. 6 is a section along line T-T of FIG. 9, FIG. 7 is a section along line U-U of FIG. 9, FIGS. 8(a) and 8(b) are diagrams showing the connector in its partially locked state, FIG. 9 is a perspective view of the connector in its fully assembled state, FIG. 10 is a perspective view of a module side connector as a male connector, FIG. 11 is an exploded perspective view of the connector when it is used of friction type, and FIGS. 12(a) and 12(b) are exploded perspective views of a prior art connector. Hereafter, one embodiment of the invention is described with reference to the accompanying drawings. As shown in FIG. 1, a connector for connecting an optical fiber cable is of full lock type which is securely coupled with a module side connector 30 (see FIG. 10) connected with a photoelectric device by means of locking arms. This cable side connector includes a housing 10 and a fixing member 20 securely mounted in the housing 10. The fixing member 20 is of synthetic resin and, as shown in FIGS. 4 and 5, includes a holding plate 21 formed with an insertion hole 21a through which an optical fiber cable A is inserted, a pair of flexible core retainers 22 formed on the holding plate 21, a pair of coating retainers 23, and locking portions 24, and locking arms 25. As shown in FIGS. 4 and 5, the pair of core retainers 22 are opposed to each other with the insertion hole 21a of the holding plate 21 therebetween and project forward so as to extend along the optical fiber cable A inserted through the insertion hole 21a. Each core retainer 22 is formed at the inner surface of its leading end with a projection 22a for pressing a core a of the optical fiber cable A where an insulation b is peeled off and at the outer corner portion of its leading end with a tapered face 22b. A distance between the projections 22a is set equal to or larger than an outside diameter of the core a by about 0.1 mm. Further, as shown in FIG. 5, each retainer 22 is formed with a stepped portion 22c in a position more forward (to the left in FIGS. 4 and 5) than the retainer 23. The end face of the coating b of the optical fiber cable A inserted into the hole 21a comes into contact with the stepped portions 22c, thereby being positioned. Similar to the core retainers 22, as shown in FIGS. 4 and 5, the pair of coating retainers 23 are opposed to each other with the insertion hole 21a of the holding plate 21 therebetween, but the positions thereof are displaced by 90° from those of the core retainers 22 with respect to the insertion hole 21a. Each retainer 23 is formed with a projection 23a engageable with an insertion groove 12c formed in the housing 10 and a projection 23b for pressing the coating b of the optical fiber cable A at the inner and outer surfaces of its leading end, respectively. A tapered face 23c which tapers toward the leading end of the retainer 23 is formed on the projection 23a on the outer surface. A distance between the projections 23b is set equal to or larger than an outside diameter of the coating b by about 0.1 mm. Since the retainers 23 are adapted to retain the coating b of the optical fiber cable A, they are located more backward than the core retainers 22. Thus, the length of the retainers 23 is shorter than that of the retainers 22. As shown in FIGS. 5 and 8(a), the locking portions 24 are U-shaped with bent leading ends, and project forward from the opposite sides of the holding plate 21. Projections 24a engageable with a stepped portion 12h of the housing 10 to be described later are formed at the opposite sides of the leading end of each locking portion 24 (see FIG. 8(a)). As shown in FIGS. 1 and 5, each locking arm 25 includes an arm main body 26 connected with the corresponding locking portion 24 and a locking claw 27 formed at the leading end of the arm main body 26. Each arm main body 26 includes a first arm 26a one end of which is connected with the outer surface of the leading end of the corresponding locking portion 24 and which extends obliquely outward along the locking portion 24 to a position adjacent the holding plate 21, and a second arm 26b which is bent outward and extends forward from the other end of the first arm 26a. The second arm 26b is bent inward in its intermediate position. The locking claw 27 is formed on the inner surface of the leading end of each second arm 26b. Accordingly, when the rear ends of the second arms 26b are pressed inward, the first arms 26a are deflected inward, with the result that the leading ends of the second arms 26b are move outward apart from each other. As shown in FIGS. 1 to 3, the housing 10 includes a ferrule 11 into which the core a of the optical fiber cable A from which the insulation b is peeled off is inserted and which positions the optical fiber cable A and a housing main body 12 for accommodating the fixing member 20 retaining the optical fiber cable. The ferrule 11 and the housing main body 12 are unitarily formed of synthetic resin, similar to the fixing member 20. Projections 13 are formed on the outer surface of the leading end of the housing main body 12. When the cable side connector is inserted into a receptacle 31 formed in the module side connector 30 as a mating connector shown in FIG. 10, the projections 13 press the surface of the receptacle 31 to readily secure the coupling state of the connectors with its frictional force. Particularly, the surface of the receptacle is provided with projections 33 which correspond to the projections 13 of the cable side connector. The housing main body 12 includes a first receptacle 12a which acts to press the core retainers 22, and a second receptacle 12b which is larger than the first receptacle 12a, acts to press the coating retainers 23 and facilitate insertion of the core retainers 22. The second receptacle 12b is formed with the insertion grooves 12c with which the projections 23a are engaged to guide insertion of the coating retainers 23. Tapered faces 12d and 12e which taper toward the leading end of the housing main body 12 are formed at stepped portions between the second receptacle 12b and the first receptacle 12a and between the leading end of the insertion grooves 12 and the second receptacle 12b, respectively. On the outer surface of the housing main body 12, there are formed projections 12f engageable with the locking portions 24 of the fixing member 20. A tapered face 12g which tapers toward the rear end of the housing main body 12 is formed on each projection 12f. Stepped portions 12h engageable with the projections 24a are formed behind the projections 12f (see FIG. 8(a)). Engagement of the projections 24a with the stepped portions 12h as shown in FIG. 8(a) prevents the fixing member 20 from getting out of the housing main body 12. In this way, the fixing member 20 is partially locked in the housing main body 12. At this stage, the projections 23a of the retainers 23 are loosely fitted in the insertion groove 12c of the housing main body 12 and the retainers 22 are loosely received within the second receptacle 12b. Thus, the second receptacle 12b and the insertion groove 12c form a receptacle for loosely receiving the retainers 22 and 23 as shown in FIG. 8(b). The optical fiber cable A can be set in the fixing member 10 by inserting the optical fiber cable A through the insertion hole 21a of the holding plate 21. In the partially locked position, the optical fiber cable A can be easily inserted since the distance between the projections 22a and the distance between the projections 23b are, as described above, equal to or slightly larger than the outside diameter of the core a and the outside diameter of the coating b, respectively. The optical fiber cable A is attached to the cable side connector assembled as described above as follows. The optical fiber cable A having the leading end where the insulation b is peeled off is inserted through the insertion hole 21a of the fixing member 20 partially locked in the housing 10 as shown in FIGS. 8(a) and 8(b), such that the core a and the coating b are retained by the retainers 22 and 23, respectively. In this position, the coating b abuts the stepped portions 22c of the core retainers 22. When the fixing member 20 is pressed forward with the projections 23a fitted in the insertion grooves 12c, the leading ends of the retainers 22 and 23 smoothly enter the first and second receptacles 12a and 12b because of the presence of the tapered surfaces 22b, 12d and 23c, 12e, respectively, with the result that the retainers 22 and 23 are pressed inward. At this time, since the outward deflection of the retainers 22 is restricted by the first receptacle 12a of the housing main body 12, the end face of the insulation b will not get disengaged from the stepped portions 22c even if the fixing member 20 is inserted with a strong force. Thus, the optical fiber cable A can be securely positioned and the retainers 22 are not damaged. As a result, the first receptacle 12a and the second receptacle 12b act as pressing portions for pressing the projections 22b and 23b against the core a and the coating b of the optical fiber cable A, respectively, and the optical fiber cable A is secured by the fixing member 20. Simultaneously, the locking portions 24 are smoothly engaged with the projections 12f because of the presence of the tapered faces 12g, and thereby the fixing member 20 is secured to the housing main body 12 as shown in FIG. 9. When the leading end of the cable side connector thus assembled is inserted into the receptacle 31 of the module side connector 30 as a mating connector shown in FIG. 10, the projections 13 formed on the housing 10 press the inner wall of the receptacle 31, thereby readily securing the connectors with its frictional force. Simultaneously, the locking claws 27 of the locking arms 25 formed at the fixing member 20 are engaged with engaging projections 32 of the module side connector 30, thereby strongly coupling the connectors. At this time, the projections 13, cooperating with the corresponding projections 33 of the surface of the receptacle, act as springs to constantly press the ferrule 11 forward. The cable side connector in its coupled state is detached from the module side connector 30 as follows. When the rear ends of the second arms 26b of the locking arms 25 are pressed inward, the leading ends of the second arms 26b move wider open, thereby disengaging the locking claws 27 from the engaging projections 32. In this way, the connectors can be easily detached. If a fixing member 20' without locking arms as shown in FIG. 11 (the fixing member 20' has the structure identical to the fixing member 20 except that it has no locking arms, and therefore like elements are identified by like reference numerals) is used instead of the fixing member 20, the cable side connector can be used as of friction type which is readily coupled with the module side connector only by means of the projections 13. Since the housing 10 is commonly used for the both types, the ferrule 11 is not displaced relative to the module side connector, thus causing no variation in optical coupling of the photoelectric devices with the optical fiber cables A. Although the invention is described with respect to the cable side connector to be coupled with the module side connector in the foregoing embodiment, its application is not limited to this. For example, the invention can also be applied to connectors for connecting the optical fiber cables. As described above, in an inventive connector for connecting an optical fiber cable, friction lock projections are formed on a housing unitarily formed with a ferrule and locking arms are mounted on a fixing member. Accordingly, by selectively using the fixing member with the locking arms and the one without the locking arms, this connector can be used both as of full lock type and as of friction type. Particularly, since the housing is commonly used in either case, the ferrule is not displaced relative to a mating connector, thereby suppressing a variation in optical coupling of the optical fiber cables and light emitting devices or optical coupling of the optical fiber cables. Further, the optical fiber cable can be retained by retainers formed at the fixing member, and the retainers are pressed inward upon accommodating the fixing member in the housing, with the result that the optical fiber cable is strongly retained. Further, the fixing member can be smoothly inserted into the housing because of the presence of tapered faces. Thus, the optical fiber cable can be easily secured in the connector, thereby considerably improving operability. If each retainer for retaining a core of the optical fiber cable is formed with a contact portion with which the end face of an insulation of the optical fiber cable comes into contact, it is very convenient because the optical fiber cable is automatically positioned when the optical fiber cable is placed in the fixing member. LIST OF REFERENCE NUMERALS 10 Housing 11 Ferrule 12 Housing Main Body 13 Projection 20 Fixing Member 21 Holding Plate 22 Core Retainer 23 Coating Retainer 24 Locking Portion 25 Locking Arm 26 Arm Main Body 26a First Arm 26b Second Arm 27 Locking Claw

Claims: A connector for connecting an optical fiber cable (A), comprising a housing (10) unitarily formed with a ferrule (11), and a fixing member (20; 20') which is adapted to be fitted in said housing (10) and to secure the optical fiber cable (A), characterized in that the fixing member (20; 20') is formed with locking means (24) for locking the fixing member (20; 20') with said housing (10) and in that a coupling structure (13, 25) is provided on the connector for coupling the connector with a mating connector (30), whereby friction lock projections are formed on the housing (10) and the fixing member (20) is formed selectively with or without locking arm means (25), wherein the ferrule (11) is not displaced relative to the mating connector (30), irrespective of said coupling structure (13, 25). A connector according to claim 1, wherein: the fixing member (20) comprises a holding plate (21) formed with an insertion hole (21a) through which the optical fiber cable (A) is inserted, flexible retainers (22, 23) extending forward from the holding plate (21), and locking portions (24). A connector according to claim 2, wherein the retainers (22, 23) are adapted to retain a core (a) and a coating (b) of the optical fiber cable (A) inserted through the insertion hole (21a), respectively, and a projection (22a, 23b) for pressing the optical fiber cable (A) is formed on the leading end of each retainer (22, 23). A connector according to claim 2 or 3, wherein each of the locking arms (25) comprises a flexible arm main body (26) connected with the leading end of each locking portion (24), and a locking claw (27) formed at the leading end of each arm main body (26) and engageable with the corresponding engaging portion (32) of the mating connector (30). A connector according to any of claims 2 to 4, wherein the housing (10) is formed with a receptacle (12b, 12c) for loosely receiving the retainers (22, 23) formed at the leading end of the fixing member (20), and a pressing portion (12a, 12b) formed contiguous with the receptacle (12b, 12c) for pressing the retainers (22, 23) against the optical fiber cable (A). A connector according to claim 5, wherein a tapered face (22b, 23c, 12d, 12e) is formed on at least one of the outer sides of the leading ends of the retainers (22, 23) and stepped portions between the receptacle (12b, 12c) and the pressing portion (12a, 12b) of the housing (10). A connector according to claim 5 or 6, wherein the locking portions (24) are engaged with engaging portions (12f) formed on the housing (10) to lock the fixing member (20) when the retainers (22, 23) are positioned at the receptacle (12b, 12c) and the pressing portion (12a, 12b) of the housing (10), respectively. A connector according to any of claims 4 to 7, wherein each arm main body (26) comprises a first arm (26a) which extends backward from the leading end of the corresponding locking portion (24) toward the holding plate (21) of the fixing member (20) along the locking portion (24) and a second arm (26b) which is bent at the rear end of the first arm (26a) and extends forward, and the locking claw (27) is formed at the leading end of each second arm (26b). A connector according to any of claims 2 to 8, wherein the retainer (22) for retaining the core (a) of the optical fiber cable (A) is formed with a contact portion (22c) with which the end face of the coating (b) of the optical fiber (A) comes into contact. Connector assembly comprising a connector according to one or more of the preceding claims and a mating connector (30) provided with projection (33) being engageable with the corresponding friction lock projection (13) of the housing (10) and with an engaging portion (32) being engageable with the corresponding locking arm means (25) if present on the fixing member (20).

Inventors: KAWAMURA SHIGETO, KAWAMURA, SHIGETO, KAWAMURA, SHIGETO, C/O SUMITOMO WIRING SYSTEMS LTD
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1995
Main classification: G02B6
IPC codes: G02B6