Slide Fit Optical Connector Having End Cap to Prevent Rotation

The field of the invention is fiber optic connectors.

As fiber optic local area networks and the telephony subscriber loop begin to make a large impact on the market for fiber optic connectors and splices, users are finding that most connectors were not designed for field installation. This was not a problem when installation of connector pigtails, that is, a predetermined length of fiber to be joined to a system fiber with a splice, was the norm; but direct connectorization is now becoming common. Installing a typical fiber optic connector requires a lengthy process of heat curing epoxy and polishing the fiber end. Other connectors have eliminated the epoxy and polish steps, but they do so at the expense of performance and longevity. Still other connectors rely on ultraviole cured adhesive to secure a fiber into a splice. While this method is quicker and easier than the heat cured epoxy method, it requires the user to have an adhesive which has a finite shelf life and an ultraviolet curing lamp.

Therefore, there is seemingly a need for connectors requiring no epoxy or curing in the field but maintaining desirable performance and longevity.

The connector according to the invention is designed to allow the curing and polishing steps usually performed in the field for fiber optic connectorization to be moved into the factory. In the field, the steps to complete connectorization are similar to those for installing a mechanical splice. This process is accomplished by centering the connector through a slide fit process, keeping the connector rotationally and longitudinally stable while doing so, and securing the optical fiber to be connected by crimping. The resulting connector can then be placed into communication with other connectors through the use of standard connector sleeves and connector sleeve adapters.

The following detained description of the preferred embodiment is made with reference to the several figures, in which:

FIG. 1 is an enlarged perspective view of the connector prior to introduction of the optical fiber to be connected;

FIG. 2 is a longitudinal sectional view of the apparatus shown in FIG. 1 along sectional lines 2--2 of FIG. 1;

FIG. 3 is a perspective view of the process of introducing the optical fiber to be connected into the apparatus of FIG. 1 while such apparatus is held by an insertion tool;

FIG. 4 is an expanded fragmentary view of FIG. 3 after the tool has moved the sliding member;

FIG. 5 is a perspective view of the completed connector joined to an optical fiber in a cable;

FIG. 6 is a perspective view of the connector joined to a buffered optical fiber;

FIG. 7 is a longitudinal sectional view of the completed connector of FIG. 5;

FIG. 8 is an enlarged perspective view of the end cap; and

FIG. 9 is an enlarged fragmentary sectional view of the apparatus shown in FIG. 1 with the end cap inserted.

The portion of the connector which is preassembled in the factory is as shown in FIGS. 1 and 2. Optical fiber 12 is placed in ferrule 10, with one end of optical fiber 12 being polished to a smooth finish with the end of ferrule 10 having the smaller outer diameter. The other end of optical fiber 12 is cleaved and extends to the middle of housing 11. Optical fiber 12 may be secured within ferrule 10 by an epoxy.

A centering assembly is placed into housing 16. The preferred centering assembly is that shown in U.S. Pat. 4,787,704, issued to Knecht and Dean, which is incorporated herein by reference.

Knecht and Dean show in FIG. 1 thereof a frame 11, rods 15-17 and 16-18, and lid 10, all of which may be utilized in this preferred embodiment. To the curved portion of frame 11 of Knecht and Dean is now attached first rib 40, which extends through slot 41 of housing 16. In practice, rods 15-17 and 16-18 of Knecht and Dean are placed in channel 19 of frame 11 of Knecht and Dean (as modified by attaching first rib 40 thereto). Then first rib 40 is inserted using tweezer into housing 16 with first rib 40 placed through housing slot 41. Then lid 10 of Knecht and Dean is inserted into housing 16. Optical fiber 12 is then coated with epoxy and inserted into ferrule 10. The assembly of ferrule and fiber is then fitted into housing 16 and the centering assembly, respectively, as shown in FIGS. 1 and 2 herein. The outside of metal crimp tube 18 is coated with epoxy and fitted to housing 16 as shown in FIGS. 1 and 2.

Next referring to FIG. 9, dust cap 23 is formed of a rigid plastic, having a slot 39 and opposing small exterior knobs, one of which is visible, to connect with bayonet 11 as described below. Dust cap 23 is placed over ferrule 10 with slot 39 fitted on housing rib 15 to lock end cap 23 and housing 16 with respect to rotation. Coil spring 17 is then placed over housing 16 from the end opposite dust cap 23. Bayonet 11 is then placed over spring 17, bayonet 11 turned so that the exterior knobs of dust cap 23 fit into its interior grooves. Slider (locking member) 14 is then placed over the tip of housing 16 opposite dust cap 23. The apparatus at this point is as shown in FIGS. 1 and 2, with the addition of end cap 23 as shown in FIG. 9.

The user now takes in hand cable 28 which is to be affixed to the connector. Cable 28 is inserted through boot 26 and crimp ring 32. The connector assembly is placed into a crimping tool as shown in FIG. 3. The crimping tool has jaws 19 and 20, which are terminated with one terminal end 22 shaped to grip end cap 23 to prevent its rotation and another terminal end 21 having fingers to apply force to slider 14. The end portion of cable 28 is stripped away, revealing buffered optical fiber 30, which is properly stripped, cleaved and loaded through crimp tube 18 until it meets the terminal end of optical fiber 12. The tool is closed as shown in FIG. 4, slider 14 urged inward to slide to the second position over tab 40, urging tab 40 radially inward through slot 41 to center the connector.

Hole 24 of the crimp tool is then used to crimp tube 18. With reference o FIG. 7, strength members 31 are spread over the exterior of housing 16, crimp ring 32 is placed over housing 16 and strength members 31, and tool hole 2 is used to crimp the crimp ring 32. Boot 26 is then placed over crimp ring 32. Boot 26 may be scored at notch 35 to accommodate cable 28.