Rotatably polarizing keying element for a polarized connector

#This invention relates generally to polarized connectors and, more particularly, to a keying element for configuring a connector to one of several allowed polarizations.

#Fiber Distributed Data Interface (FDDI) connectors are used for data transmission in, among other things, computer systems and particularly local area networks. Typical FDDI connectors include a connector body having an entrance at one end for receiving a fiber optic cable. The fiber optic cable breaks out inside the connector body into two separate optical fibers that are attached to, and terminate in, two ferrules. The connector body mates with one of several different receptacles including, for example, an active device receptacle, a transceiver adaptor, a dual ST-coupling, or an FDDI to FDDI coupling.

#The receptacles typically include a spline cooperating with a connector key or polarizing element to ensure that the particular receptacle being used is compatible with the mated connector. See U.S. Pat. No. 5,166,995 to Weber, the teachings of which are specifically incorporated herein by reference. There are generally four basic keying formats in the American National Standards Institute (ANSI) protocol, that is the A, B, M ("Master")and S ("Slave") polarizations as disclosed in FDDI:X3.166-1990; ISO/IEC 9314-3 and X3T9.5/88-155 the teachings of which are hereby incorporated by reference. The polarizations are achieved by the size and placement the spline in the cooperating receptacle. For example, a connector polarized in the S configuration has a centrally disposed full width channel. The "A" polarization is a partial width channel located to the right of center, while the "B" polarization is a partial width channel located to the left of center. The "M" polarization is a partial width channel located at the center of the connector.

#FIG. 1 is an perspective view of an FDDI connector having a key according to the teachings of the present invention.

#FIG. 2 is an exploded, perspective view of the connector of FIG. 1.

#FIG. 3 is an perspective view of the top half of the connector of FIG. 1.

#Referring now to the drawings wherein like reference numerals refer to like elements, polarized FDDI connector is shown in FIG. 1. While the present invention is particularly suited for FDDI style connectors and devices, it will be recognized by those with skill in the art that the polarized connectors and keys described and claimed herein will be useful for any connector which must operate according to multiple polarizations.

#Connector 10 comprises a connector body 20 having a channel 190 with an opening 30 therein to receive a polarization key 40. The key 40 mechanically rotates in the opening 30 to an appropriate position to change the polarization of the connector 10. The connector 10 houses a fiber optic cable 50 protected by bend relief element 60 as is conventionally known in the art. Inside the connector 10, the fiber optic cable 50 is distributed and preferably terminates in at least two ferrules 70. The connector 10 mates with a receptacle (not shown) having a polarizing spline member. The connector 10 comprises a top half 80, shown in FIG. 3, and a bottom half 90, shown in FIG. 4, molded from a thermoplastic material such as polyester or nylon. The channel 190 and opening 30 are molded in the top half 80 of the connector 10 to receive the polarization key 40 therein. A bottom half 90 is molded with reciprocal receiving element 100 having a size and position corresponding to the opening 30. To assemble the connector 10, the terminated ferrules 70 and fibers 50 are placed in their respective positions in the bottom half 90 of the connector 10. The top half 80 of the connector 10 is latched to the bottom half 90 to form an FDDI connector as shown substantially in FIG. 1 with opening 30 and reciprocal receiving element in substantial alignment. Polarization key 40 is inserted into opening 30 and reciprocal receiving element 100 where the key may be rotated to complete the assembly.

#With reference to FIGS. 3 and 4, the top half 80 of connector 10 has a full width channel 190 to cooperate with the spline in a mating receptacle (not shown). As known by those with skill in the art, the spline member cooperates with a channel in the connector to ensure that the particular receptacle is compatible with the mating connector. The connector 10, therefore, is intrinsically configured for the S polarization without a polarizing element. The FDDI polarizations for multimode fiber are termed A, B, M, and S polarizations and represent the four basic polarization formats for multimode fiber. The FDDI polarizations for singlemode fiber are termed SA, SB, SM, and SS polarizations and represent the four basic polarization formats for singlemode fiber.