Rotationally adjustable fiber optic connector

A fiber optic connector assembly includes an outer connector housing defining an optic axis. An inner optical fiber plug is mounted in the housing for limited axial movement therein and for rotational movement angularly of the axis. An indexing or locking mechanism is provided between the plug and the housing to hold the plug in selected rotational positions of adjustment angular of the optic axis. Axial movement of the plug within and relative to the housing is effective to disengage the lock or indexing mechanism and allow rotation of the plug. A retainer is selectively movable into engagement with the plug to prevent axial movement of the plug and, thereby, prevent disengagement of the lock or indexing mechanism, thereby fixing the rotational position of the adjustment of the plug.

FIELD OF THE INVENTION

This invention generally relates to the art of fiber optic connectors and, particularly, to a connector wherein an optical fiber is angularly adjustable about its axis and is maintainable in a selected rotational position of adjustment.

BACKGROUND OF THE INVENTION

Fiber optic connectors of a wide variety of designs have been employed to terminate optical fiber cables and to facilitate connection of the cables to other cables or other optical fiber transmission devices. A typical fiber optic connector includes a ferrule which mounts and centers an optical fiber or fibers within the connector. The ferrule may be fabricated of such material as ceramic. A ferrule holder or other housing component of the connector embraces the ferrule and may be fabricated of such material as molded plastic. A spring typically is disposed within the housing or ferrule holder such that the ferrule is yieldably biased forwardly for engaging another fiber-mounting ferrule of a mating connector device. Some fiber optic connectors allow for angular adjustment of the optical fiber within the connector to achieve an optimum angular position of the fiber whereat the insertion losses of the connector are at a minimum. For instance, indexing means may be provided within the connector to define and hold the fiber-terminating ferrule in any one of a plurality of rotational positions. During or after assembly, the ferrule is rotated from one position to another sequentially, with the insertion losses measured at each position. When the optimum position is determined, the ferrule is assembled in the optimum position of adjustment, and the connector is ready for mating with a complementary connector or other fiber transmission device. In other connectors, the optimum angular position or orientation is achieved by polishing the end face of the ferrule and the optical fiber terminated therewithin.

A problem continues to be encountered with adjustable fiber optic connectors as described above. Specifically, after termination of the fiber within the connector, and after the optimum angular position of the fiber-terminating ferrule is determined, or the end face of the ferrule and fiber are polished, the ferrule and fiber often are accidentally rotated away from the optimum angular position thereof, as described above. This typically occurs because of the spring loading of the ferrule or ferrule holder, whereby the ferrule can he accidentally pushed inwardly against the spring forces and accidentally rotated out of or away from the optimum rotational position of adjustment. The present invention is directed to a system which prevents this type of accidental change in the angular position of the optical fiber within the fiber optic connector.

SUMMARY OF THE INVENTION

An object, therefore, of the invention is to provide a new and improved fiber optic connector of the character described.

In the exemplary embodiment of the invention, a fiber optic connector assembly includes an outer connector housing defining an optic axis. An inner optical fiber plug terminates an optical fiber and is mounted in the housing for limited axial movement therein, and for rotational movement angularly of the axis. Complementary interengaging lock means are provided between the plug and the housing to hold the plug in selected rotational positions of adjustment angularly of the axis. Axial movement of the plug within and relative to the housing is effective to disengage the lock means and allow rotation of the plug. Retaining means are selectively movable into engagement with the plug to prevent axial movement of the plug and, thereby, prevent disengagement of the lock means, thereby fixing the rotational position of adjustment of the plug.

As disclosed herein, the lock means between the plug and the housing is provided by a complementary interengaging rotary indexing means which includes an orthogonal socket in a through passage of the housing for receiving a complementary orthogonal plug portion of the optical fiber plug. The retaining means is engageable with the plug to prevent disengagement of the rotary indexing means.

According to an aspect of the invention, spring means are provided for normally biasing the plug forwardly to engage the rotary indexing means but allow the plug to be Oselectively moved rearwardly to disengage the rotary indexing means and, thereby, allow rotational adjustment of the optical fiber plug. The spring means is provided by a coil spring encircling the plug and engaging a radially projecting flange on the plug to normally bias the plug forwardly. The retaining means is provided by a retainer clip selectively engagement behind the radially projecting flange to prevent disengagement of the rotary indexing means. The housing includes an opening for insertion of the retainer clip from exteriorly of the housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in greater detail, and first toFIGS. 1-3, the invention is embodied in a fiber optic connector assembly, generally designated10, which includes an outer connector housing, generally designated12, having a front mating end12a, a rear end12band a through passage14extending between the ends and defining an optic axis16. Housing12is a two-part housing which includes a front housing part18and a rear housing part20. The front housing part has a pair of latch openings22in opposite sides thereof for receiving a pair of chamfered latch bosses24on opposite sides of rear housing part20when the housing parts are assembled as seen in FIG.1. Typically, the housing parts are molded of plastic material whereby latch bosses24snap automatically into latch openings22when the housing parts are assembled. The front housing part also has a latch arm26which is flexible in the direction of double-headed arrows “A”. The latch arm has a pair of latching ears26aon opposite sides thereof for latching engagement with appropriate latch means on a complementary mating connector, a mating adapter or other mating optical transmission device. Rear housing part20has a flexible actuator arm28having a serrated top surface28a, for engagement by an operator, such as an operator's thumb, for depressing latch arm26downwardly toward the connector assembly. Pressing down on actuator arm28depresses flexible latch arm26which is effective to unlatch latching ears26afrom appropriate latch means on the mating connector, thereby allowing unmating of the connectors. Finally, a strain relief boot30projects rearwardly of the rear housing part to provide strain relief for a fiber optic cable32.

An inner optical fiber plug, generally designated34(FIGS.2and3), is provided for terminating at least one optical fiber of fiber optic cable32. The plug is disposed in through passage14in housing12as is seen best in FIG.5. The plug is disposed in the through passage for limited axial movement therein, as will be apparent hereinafter, the limited axial movement being on optic axis16.

Optical fiber plug includes a ferrule36which mounts and centers the optical fiber of fiber optic cable32, on optic axis16. The ferrule may be fabricated of such material as ceramic. A ferrule holder38embraces the ferrule and may be fabricated of such material as molded plastic. A coil spring40surrounds a rear tubular portion44of the optical fiber plug. The rear tubular portion may be integral with ferrule holder38. The ferrule holder is larger in diameter than the rear tubular portion, and a washer-like member46abuts against a rear face of the ferrule holder. In assembly of fiber optic connector assembly10, and as best seen inFIG. 5, a rear end40bof coil spring40abuts against a shoulder42circumferentially about through passage14in rear housing part20. Therefore, the coil spring is compressed between shoulder42and the radially projecting flange provided by washer46. This is effective to bias optical fiber plug34, including ferrule36, ferrule holder38and rear tubular portion44, forwardly of the connector assembly in the direction of arrow “B” (FIG.5).

Generally, complementary interengaging rotary indexing means, generally designated48(FIG.5), is provided between optical fiber plug34and front housing part18to define and hold the plug and, thereby, the optical fiber of fiber optic cable32, in any one of a plurality of rotational positions of adjustment angularly about optic axis16. The rotary indexing means can be considered a complementary interengaging lock means between the plug and the housing to hold the plug in selected rotational positions of adjustment. However, it should be understood that the rotary indexing means or lock means is not limited to the specific hexagonal indexing means as described below.

Specifically, referring toFIG. 4in conjunction withFIG. 5, front housing part18includes an orthogonal socket50in through passage14. In the illustrated embodiment, the orthogonal socket is hexagonal in cross-section. As can be seen inFIG. 5, ferrule holder32is complementarily hexagonally configured for insertion into socket50. Therefore, the rotary indexing means providing by hexagonal socket50and hexagonal ferrule holder38, is effective to define six distinct rotational positions of adjustment of ferrule36and, thereby, the optical fiber angularly about optic axis16. This allows for the connector assembly to be “tuned” in order to achieve the optimum angular orientation of the fiber.

As is know in the art, tuning is achieved by placing fiber optic connector assembly10in a measuring apparatus which simulates a complementary mating connector. The insertion losses of the connector assembly (i.e., the optical losses of the optical fiber) arc measured in a given rotary position of optic fiber plug34. The plug then is pushed axially inwardly (i.e., opposite the direction of arrow “B”) against the biasing of coil spring40, until hexagonal ferrule holder38is moved out of hexagonal socket50. The plug then is indexed or rotated to the next position afforded by the orthogonal arrangement. This can be done by an operator grasping ferrule36, pushing the ferrule in and rotating the ferrule and plug to the next indexed position. Upon release of the ferrule and plug, coil spring40is effective to bias the plug forwardly and reengage the interengaging rotary indexing means. The insertion losses again are measured. This same operation is repeated until all six positions or angular orientations of the plug and fiber have been measured. The plug and fiber then are rotated to the position of optimum angular orientation whereat the insertion losses are at a minimum, whereby the connector assembly is ready to be mated in operation. This final or optimal position is maintained in the connector assembly relative to an overall keying system of the assembly. In other words, latch arm26and especially a forward mounting portion26bof the arm, forms a vertically projecting “key” which is aligned with a similar key on the mating connector. The keys provide a reference plane against which the optimum angular position of rotation of plug34can be compared.

Unfortunately, tunable or adjustable fiber optic connectors such as described above have created problems because they are prone to becoming accidentally “untuned” during handling and/or mating. In other words, inner optical fiber plug34may be accidentally rotated to an unintended rotational position of adjustment angularly of optic axis16. For instance, this can happen if the end of ferrule36is accidentally abutted against a foreign object, and the plug is pushed in and “jumps” to a different indexed position.

In order to solve the above problems, the invention contemplates a retaining means selectively movable into engagement with the plug to prevent disengagement of the rotary indexing means and, thereby, fix the rotational position of adjustment of the plug. This is effective to fix the angular position of the optical fiber relative to optic axis16and, thereby, ensure that the optical fiber is in its optimal position of minimal insertion losses.

In the exemplary embodiment, the retaining means is provided by a retainer clip, generally designated54. The retainer clip is generally U-shaped to define a pair of legs56joined by a cross portion58. A pair of teeth60project outwardly from opposite sides of each leg56. Front housing part18is provided with an opening62into which retainer clip54is inserted in the direction of arrows “C” (FIGS.3and4).

After optical fiber plug34is rotated to its optimum position of adjustment angularly of optic axis16, as described above, retaining clip54it inserted through opening62in front housing part18so the retainer clip is spaced behind washer46as seen in FIG.5. This allows for limited axial movement of optical fiber plug34without hexagonal fiber holder38moving completely out of hexagonal socket50. In other words, spring loading of the plug is desirable, if not necessary, such that ferrule36is yieldably biased forwardly for engaging another fiber-mounting ferrule of a mating connecting device. Yet, retainer clip54prevents disengagement of the hexagonal rotary indexing means.

FIG. 6shows that legs56of retainer clip54are inserted into grooves64in front housing part18. Teeth60at opposite edges of the legs bight into the plastic material of the front housing part at opposite sides of grooves64to hold the retainer clip in its inserted position. Double-headed arrow “D” inFIG. 6shows the axial distance that optical fiber plug34can yield against coil spring40without disengaging the hexagonal rotary indexing means.FIG. 7shows that front housing part18includes a pair of small openings66for receiving the distal ends of legs56of the retainer clip when the retainer clip is fully inserted into the housing.

Although the invention is described herein primarily for use with an optical fiber plug which terminates a normal optical fiber, the invention has applicability for use with other types of fibers. For instance, a polarization maintaining (PM) fiber could he terminated and must be maintained in a given angular orientation within the connector assembly.