Fiber optic connector sub-assemblies having a front-loading locking ferrule holder and related fiber optic components, devices and methods

A fiber optic connector inner housing employing a front-loading retention feature for receiving and retaining a ferrule holder, and related fiber optic connectors, cables, and methods are disclosed. In one example, the inner housing has an opening extending therethrough and at least one bayonet locking mechanism that includes an insertion slot, a rotation slot, and a retention slot disposed in an interior surface of the opening. A ferrule holder having a key portion is inserted into the opening such that the key portion is received by the insertion slot. The ferrule holder is next rotated in the rotation slot and released such that a bias member within the inner housing moves the key portion of the ferrule holder into the retention slot, thereby retaining the ferrule holder in the inner housing and preventing accidental removal of the ferrule holder from the inner housing.

BACKGROUND

The disclosure relates generally to fiber optic connector sub-assemblies, and more particularly to a fiber optic connector sub-assembly that includes a front-loading locking ferrule holder, which may be used in assembly of fiber optic connectors. Related components, devices and methods are also disclosed.

Benefits of utilizing optical fiber include extremely wide bandwidth and low noise operation. Because of these advantages, optical fiber is increasingly being used for a variety of applications, including but not limited to broadband voice, video, and data transmission in communications networks. As a result, communications networks include a number of optical interconnection points in fiber optic equipment and between fiber optic cables in which optical fibers must be interconnected via fiber optic connections. To conveniently provide these fiber optic connections, fiber optic connectors are provided. A fiber optic connector includes a housing that provides internal components for receiving, supporting, protecting, and aligning one or more end portions of optical fibers exposed from a fiber optic cable(s) when mated with other fiber optic connectors or adapters provided in fiber optic equipment or fiber optic cables. Fiber optic connectors may be installed on fiber optic cables in the field. Alternatively, fiber optic cables may be “pre-connectorized” during the manufacturing of the fiber optic cables.

In this regard, a fiber optic connector typically employs a fiber optic connector sub-assembly having a plurality of components. For example,FIG. 1shows a view of an exemplary fiber optic connector sub-assembly10for a conventional SC-type connector. The connector sub-assembly10is assembled by inserting a ferrule holder12having a ferrule14mounted thereon into a rear opening16of an inner housing18. The ferrule14extends through the inner housing18to a front opening (not shown) of the inner housing18. A spring20is then disposed around the end of the ferrule holder12and a crimp body22is inserted into the rear opening16of the inner housing18around the ferrule holder12and spring20. The crimp body22has a plurality of radial teeth24that align with grooves26within the rear opening16of the inner housing18, and a snap fit flange28that securely mates with a complementary snap fit feature (not shown) within the inner housing18. An unterminated fiber optic cable30can then be passed through the crimp body22to be mated with the ferrule holder12for final assembly of the connectorized optical cable.

These and other methods of assembling fiber optic cable connectors include a number of mechanical steps and typically may include manual labor. The influence of manual labor in the assembly process provides cost, affects consistency, and can decrease throughput in processing fiber optic connector terminations. Automated fiber optic connector termination processes for fiber optic cable preparations have been employed to reduce manual labor influence, but at significant capital costs. Even so, these automated fiber optic connector termination processes may not be flexible with respect to terminating varieties of fiber optic connectors or fiber optic cable types. Further, with these fiber optic connector termination processes, if one fiber optic connector termination fails, it must be reworked or the entire fiber optic cable must scrapped. In either case, the fiber optic cable assembly can be delayed, thereby disrupting fiber optic cable assembly throughput and increasing scrapped fiber optic cables, increasing costs as a result.

No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.

SUMMARY

Embodiments disclosed herein include fiber optic connector inner housing employing a front-loading retention feature for receiving and retaining a ferrule holder. Related fiber optic connectors, cables, and methods are also disclosed. In one embodiment, inner housing includes an inner housing having an opening extending therethrough. An interior surface of the opening includes a bayonet locking mechanism having an insertion slot, a rotation slot, and a retention slot, and a bias member mounting portion for mounting a bias member. A ferrule holder having a key portion is inserted into the opening such that the key portion is received by the insertion slot and the bias member is disposed between the ferrule holder and the bias member mounting portion. The ferrule holder is next rotated such that the key portion rotates within the rotation slot. The ferrule holder is then released such that the bias member moves the key portion of the ferrule holder into the retention slot, thereby retaining the ferrule holder in the inner housing and preventing accidental removal of the ferrule holder from the inner housing. This arrangement simplifies assembly of a fiber optic connector sub-assembly and provides secure retention of the ferrule holder within the inner housing.

One embodiment of the disclosure relates to a fiber optic connector inner housing for mounting and retaining a ferrule holder as part of a fiber optic connector sub-assembly. The inner housing includes an inner housing having an opening extending therethrough, wherein the opening comprises a front end, a rear end, and an interior surface. The inner housing further includes at least one bayonet locking mechanism. Each bayonet locking mechanism comprises an insertion slot disposed in the interior surface of the opening configured to receive a respective key portion of a ferrule holder when the ferrule holder is inserted into the front end of the opening. Each bayonet locking mechanism further comprises a rotation slot disposed in the interior surface of the opening for rotating the key portion of the ferrule holder away from the insertion slot. Each bayonet locking mechanism further comprises a retention slot disposed in the interior surface of the opening for retaining the ferrule holder in the inner housing.

An additional embodiment of the disclosure relates to a fiber optic connector sub-assembly. The fiber optic connector sub-assembly includes an inner housing comprising an inner housing having an opening extending therethrough, wherein the opening comprises a front end, a rear end, and an interior surface. The inner housing also includes at least one bayonet locking mechanism comprising an insertion slot disposed in the interior surface of the opening,

a rotation slot disposed in the interior surface of the opening, and a retention slot disposed in the interior surface of the opening. The fiber optic connector sub-assembly further includes a bias member mounting portion disposed at the rear end of the opening, a ferrule holder having a key portion disposed in the inner housing, and a bias member disposed in the inner housing between the ferrule holder and the bias member mounting portion. The insertion slot is configured to receive the key portion of the ferrule holder when the ferrule holder is inserted into the opening. The rotation slot is configured to allow the ferrule holder to be rotated away from the insertion slot. The bias member is configured to move the key portion of the ferrule holder into the retention slot when the ferrule holder is released, thereby retaining the ferrule holder in the inner housing.

An additional embodiment of the disclosure relates to a method of assembling a fiber optic connector sub-assembly. The method comprises providing an inner housing comprising an inner housing having an opening extending therethrough, wherein the opening comprises a front end, a rear end, and an interior surface. The inner housing further includes at least one bayonet locking mechanism comprising an insertion slot disposed in the interior surface of the opening, a rotation slot disposed in the interior surface of the opening, and a retention slot disposed in the interior surface of the opening. The inner housing further includes a bias member mounting portion disposed at the rear end of the opening. The method further includes providing a bias member in the inner housing adjacent the bias member mounting portion. The method further includes inserting the ferrule holder into the front end of the opening of the inner housing such that the key portion is received by the insertion slot and the bias member is disposed between the ferrule holder and the bias member mounting portion. The method further includes rotating the ferrule holder about a longitudinal axis of the opening such that the key portion rotates within the rotation slot. The method further includes releasing the ferrule holder such that the bias member moves the key portion of the ferrule holder into the retention slot, thereby retaining the ferrule holder in the inner housing.

DETAILED DESCRIPTION

Various embodiments will be further clarified by the following examples. In this regard,FIG. 2is an exploded isometric view of an exemplary fiber optic connector sub-assembly32having a front-loading ferrule holder34according to an embodiment. An inner housing sub-assembly36includes an inner housing38and crimp body40assembled and/or integrally formed as one piece. A spring42or other bias member is inserted into a front opening43of the inner housing sub-assembly36and a ferrule holder34having a ferrule44mounted thereon is inserted into the front opening43of the inner housing sub-assembly36through the spring42. In this example, the ferrule holder34has a pair of key portions46that align with complementary insertion slots48in an interior surface of the inner housing38to permit insertion of the ferrule holder34into the front opening of the inner housing38. As will be shown in greater detail inFIGS. 3A and 3B, each insertion slot48is part of a bayonet locking mechanism that allows the complementary key portion46of the ferrule holder34to be inserted into the insertion slot48, rotated in a rotation slot50and retained in a retention slot52. After the key portions46are locked into their complementary retention slots the key portions46are retained in the retention slots52by the bias force of the spring42pressing against the ferrule holder34. In addition, as will be discussed below with respect toFIGS. 5A and 5B, the key portions46can be further retained the retention slots52in this embodiment by complementary locking flanges (not shown) on an interior surface of a shroud54that mate with respective locking slots56on an outer surface of the inner housing38. In this manner, a number of retention mechanisms can be employed to permanently secure and retain the key portions46within their respective retention slots52, thereby securely retaining the ferrule holder34within the inner housing38. An optical fiber57extending from fiber optic cable30may be passed through the rear end of the ferrule holder34and connected to the ferrule44using conventional techniques.

In this regard,FIG. 3is a cross-sectional side view of the inner housing sub-assembly36including a detailed view of the bayonet locking mechanism of the inner housing sub-assembly36. As described above with regard toFIG. 2, the spring42is inserted into the front opening43of inner housing38. The crimp body40is connected to the inner housing38at the rear end of opening43, and a stepped surface of the crimp body40forms a bias member mounting portion58in this embodiment, which is abutted by the inserted spring42. In another embodiment, an alternative bias member mounting portion (not shown) can be formed in the inner housing38instead of on the crimp body40.

FIG. 3also illustrates how structural integrity and bend resistance of the inner housing can be maintained when including a bayonet mechanism according to different embodiments disclosed herein. For example, fiber optic inner housings are commonly formed from a moldable material such as thermoplastic. Accordingly, the limitations of molding techniques may determine the types of unitary shapes that can be produced. It is possible to form the straight insertion slot48as a groove along the longitudinal axis of the inner housing38that does not completely pass through the wall of the inner housing38because a mold pin configured to produce such a groove can be removed from the inner housing sub-assembly36in a longitudinal direction without damaging the inner housing38. However, conventional molding techniques do not permit forming the rotation channel50and retention slot52in this manner, because the mold pin could not then be removed from the inner housing38without damaging the inner housing38. Instead, conventional molding techniques require either a flange in an inner surface of the mold to contact the mold pin, thereby creating an aperture through the inner housing38, or a subsequent coring out of an aperture to form the rotation slot50and retention slot52after the molding process. Thus, at least a portion of the rotation slot50and a portion of the retention slot52extends from the interior surface of the inner housing38through an outer surface of the inner housing38in this embodiment. As can be seen fromFIG. 3, the rotation slot50and retention slot52are comparatively small in relation to the overall inner housing38. Accordingly, it can be seen in this and other embodiments that the relative size of the rotation slot50and retention slot52can be designed so as to optimize the structural integrity and bend resistance of the inner housing38.

To illustrate insertion and retention of the ferrule holder34within the inner housing sub-assembly36,FIG. 4A-4Cillustrate exemplary steps for inserting and retaining the ferrule holder34. After the spring42is disposed in the inner housing38to abut the bias member mounting portion58,FIG. 4Ashows the ferrule holder34being inserted into the front opening43of the inner housing38using an insertion force F1parallel to a longitudinal axis of the fiber optic inner housing sub-assembly36. In this embodiment, the key portions46of the ferrule holder34are protrusions that slidably engage the insertion slot48of the inner housing38during insertion.

After the ferrule holder34has been fully inserted, as shown inFIG. 4B, the rotation slot50permits each key portion46to rotate with respect to a longitudinal axis of the fiber optic connector, thereby permitting the entire ferrule holder34to be rotated about the longitudinal axis. In this embodiment, the initial rotation of the key portion46into the rotation slot50requires application of a rotational force T1in combination with maintaining the original insertion force F1, to counteract the compression of the spring42(not shown). After the ferrule holder34has been rotated, the retention slot52permits the ferrule holder34to move back toward the front opening43of the inner housing38by the spring42. In this manner, a ferrule holder34can be inserted and retained in the inner housing sub-assembly36by a simple, two-step motion.

As can be seen fromFIGS. 4A-4C, the insertion slots48, rotation slots50, and retention slots52are configured to slidably accommodate the key portions46. The retention slots52permit the key portions46to freely move longitudinally forward and backward, while providing a stop59at the front end of the retention slots52to prevent removal of the ferrule holder34and to properly align the ferrule44within predetermined tolerances with respect to the connector assembly. In addition, the key portions46are located away from the longitudinal axis of the ferule holder34. This arrangement creates a longer moment arm for the key portions46, such that rotation of the ferule holder34about the longitudinal axis permits greater control of the rotation of the key portions46and/or permits greater manufacturing tolerances for the key portions46and rotations slots50.

To prevent accidental removal of the ferrule holder34via the rotation slots50, spring42also keeps the ferrule holder34biased forward toward the opening43such that the ferrule holder34cannot be removed from the inner housing38without simultaneously applying an insertion and rotation force to the ferrule holder. In this manner, the ferrule holder34is thus also prevented from being accidentally or unintentionally removed from the inner housing sub-assembly36.

Additional features may also be included to prevent removal of the ferrule holder34from the inner housing38after the key portions46have been retained by the retention slots52. For example, a locking mechanism may be employed to physically obstruct the rotation slots50after the key portions46have been retained by the retention slots52. In this regard,FIGS. 5A and 5Bare respective front and top cutaway views of an exemplary assembled fiber optic connector sub-assembly ofFIG. 2. As discussed above with respect toFIG. 2, the inner housing may include retention slots52on an outer surface of the inner housing38. As shown inFIGS. 5A and 5B, complementary locking flanges60disposed on the interior surface of the shroud54are configured to slidably mate with the locking slots56when the inner housing sub-assembly36is inserted into the shroud54. As shown inFIG. 5B, each locking slot56is adjacent to the retention slot52and passes through the rotation slot50. Thus, when the locking flanges60are mated with the locking slots56, each locking flange60physically blocks a portion of the rotation slot50, thereby preventing the key portion46disposed in the retention slot52from being rotated out of the retention slot52. In many embodiments, the shroud54may be configured to be permanently attached to the inner housing sub-assembly36, for example through a one-way snap-fit or other conventional attachment mechanism. Thus, in this embodiment, the locking flange60of the shroud54effectively forms a permanent side wall for the retention slot52when the inner housing sub-assembly36is permanently mounted within the shroud54.

Additional features for retaining the key portion46in the retention slot52of a bayonet locking mechanism may also be employed. In this regard,FIGS. 6A and 6Bare side views of an exemplary inner housing sub-assembly62for a fiber optic connector sub-assembly showing a ramp feature for automatically rotating and retaining a ferrule holder having key portions46in the inner housing sub-assembly62. In this example, an alternative bayonet locking mechanism includes an insertion slot64, a rotation slot66, and a retention slot68. However, the rotation slot66in this example has a trapezoidal profile including a first ramp surface70for guiding a key portion46away from insertion slot64during insertion of the ferrule holder34(not shown), and a second ramp surface72for blocking and guiding the key portion46away from the insertion slot64and toward the retention slot68when the ferrule holder34is released. One advantage of this arrangement is that insertion and rotation of the ferrule holder34can be accomplished by a single longitudinal insertion force F1that does not include an external torque component.FIG. 6Aillustrates how continued application of insertion force F1causes the key portion46to engage the first ramp surface70of the rotation slot66and automatically rotate as the key portion46travels further in the longitudinal direction. As shown byFIG. 6B, the second ramp surface72causes a similar rotation toward the retention slot68as the spring42applies a bias force (i.e., counterforce) in the opposite longitudinal direction when the insertion force is released. One advantage of this arrangement is that it simplifies both manual and automated assembly by requiring a simple, one dimensional force to be applied to the ferrule holder34.

In addition, the precision of the insertion force F1can be varied in this arrangement, because the key portion46does not need to be fully rotated in the rotation slot66prior to releasing the insertion force. For example, so long as the key portion46is rotated out of the insertion slot64, the second ramp surface72will prevent the counterforce from the spring42(not shown) from moving the key portion back into the insertion slot64. Instead, the counterforce from the spring42will cause the key portion46to be rotated toward and into the retention slot68automatically by the second ramp surface72. Thus, in an automated process, the precise amount of insertion force to be applied to the ferrule holder34can have a relatively large tolerance (i.e., manufacturing window). Likewise, in a manual process, the small amount of time saved by a simplified, one-action insertion assembly process may produce substantial savings in aggregate time and labor costs.

This arrangement also permits a “prescribed displacement” system to be used, for example, to design assembly tools having appropriate tolerances. In this regard,FIGS. 6C and 6Dare simplified detail views of the bayonet mechanism ofFIGS. 6A and 6Bwith additional dimensions that may be used for determining acceptable tolerances for assembly tools.FIG. 6Cillustrates a first length A representative of a minimum allowable insertion distance for key feature46, i.e., the distance beyond which the key feature46will contact the second ramp surface when the insertion tool is released, thereby biasing the key feature toward and into the retention slot.FIG. 6Calso illustrates a second length B representative of a maximum allowable insertion distance for key feature46, i.e., the vertex between the first ramp surface70and the wall of retention slot68. Thus, an appropriate insertion tool for this design should have a length LTequal to the average of A and B plus or minus an acceptable tolerance of half the difference of B and A. This relationship is represented by Equation 1 below:

To aid in designing for specific values of A and B,FIG. 6Dillustrates a number of dimensions of the bayonet mechanism. In this regard, the three illustrated lengths L1-L3correspond to the length of the insertion slot64measured from different points in the bayonet mechanism. L1corresponds to the length of the insertion slot64measured from the vertex of the insertion slot64and second ramp surface72. L2corresponds to the length of the insertion slot64measured from the vertex of the insertion slot64and first ramp surface72. L3corresponds to the length of the insertion slot64and rotation slot66measured from the vertex of the rotation slot66and second ramp surface72.FIG. 6Dalso illustrates angle θ corresponding to the angle of the first ramp surface70, and angle α corresponding to the angle of second ramp surface72. Finally,FIG. 6Dillustrates a width I of insertion slot64, width R of retention slot68(equal to width I in this embodiment), and intermediate width W therebetween. These dimensions permit an appropriate prescribed displacement design calculation to be performed.

For example, to determine an appropriate manufacturing tool length tolerance to form the first ramp surface70for the bayonet mechanism ofFIGS. 6A-6D, the threshold longitudinal distance Tytraveled by the key portion within the rotation slot66must be determined. This distance Tyis equal to (B-A), which corresponds the longitudinal translation of the center of the key feature46from the point at which the center of the key feature rotates out of the insertion slot64(at distance A) to the point at which the key feature46abuts the far wall of the rotation slot66and the first ramp surface70(at distance B). Because the diameter of the key feature46is equal to width R in this embodiment, the distance (B-A) can be also be represented by equation 2 below.

Combining Equation 2 with Equation 1 yields the following calculation for determining LTmay be represented by equation 2 below.

Thus, as shown above, a prescribed displacement system can be used with this and other embodiments to design assembly tools that achieve reliable assembly during manufacturing while allowing for maximum allowable tolerances to keep overall manufacturing costs down.

The bayonet locking mechanism may include additional structures for preventing removal of the ferrule holder34as well. In this regard,FIGS. 7A-7Care side views of an exemplary inner housing sub-assembly74for a fiber optic connector sub-assembly showing a latch feature for automatically locking and retaining the ferrule holder in the inner housing. As shown inFIG. 7A, the rotation slot78includes a one-way flexible latch structure82that extends towards and partially obstructs the retention slot80.FIG. 7Billustrates that the latch structure82is bendable about the first ramp surface84such that the latch structure82is pushed aside by the key portion46when the key portion46is being guided into the retention slot80. However, once the key portion46is retained in the retention slot80, the latch structure82blocks and obstructs the key portion46. If an attempt is made to move the key portion46back into the rotation slot78, as shown inFIG. 7C, the key portion46will engage a free end86of the latch structure82such that the latch structure82impedes movement of the key portion46and may also resiliently deform to further block the rotation slot78.

Advantageously, and as shown inFIGS. 7A-7C, the latch structure82may designed as with first and second substantially straight sections separated by a bend. This configuration allows for a latch structure with a longer length, which helps distribute loads.

Another alternative fiber optic inner housing sub-assembly88is disclosed inFIGS. 8A-8C. In this embodiment, as shown byFIG. 8A, the fiber optic inner housing sub-assembly88includes a bayonet locking mechanism including an insertion slot90, a rotation slot92, and a retention slot94for accommodating a ferrule holder, such as ferrule holder34having key portions46and carrying ferrule44. The rotation slot92has an irregular curved profile to facilitate movement of key portion46into the retention slot94. A latch structure96also includes a ramped flange98in this embodiment. As shown byFIG. 8B, the ramped flange98has a first ramp surface100facing the rotation slot92that facilitates movement of the key portion46from the rotation slot92by moving the latch feature away from the rotation slot92when the key portion46engages the first ramp surface100. The ramped flange98also has a second ramp surface102facing the retention slot94. As shown byFIG. 8C, the second ramp surface102prevents removal of the key portion46from the retention slot94by moving the latch feature further into the rotation slot92when the key portion46engages the second ramp surface102, thereby preventing removal of the key portion46from the retention slot94.

FIGS. 9A-9Cshow another fiber optic inner housing sub-assembly104that includes a bayonet locking mechanism including an insertion slot106, a rotation slot108, and a retention slot110for accommodating a ferrule holder, such as ferrule holder34having key portions46and carrying ferrule44. As shown inFIG. 9A, a latch structure112disposed in the rotation slot108comprises a leaf spring (e.g., has a leaf spring profile). As shown inFIG. 9B, insertion of the key portion46causes the latch structure112to flatten out within the rotation slot108when the key portion46is moved through the rotation slot108toward the retention slot110. However, after the key portion46moves past the latch structure112, the leaf spring profile of the latch structure112causes the latch structure112to spring back into place. Thus, as shown inFIG. 9C, if an attempt to remove the key portion46from the retention slot110is made, the key portion46engages the free end114of the latch structure112, thereby causing the leaf spring profile to bow out toward the opposite wall of the rotation slot108and obstruct the rotation slot108.

In some embodiments, the latch structure can obstruct the interface between the rotation slot and insertion slot. In this regard,FIGS. 10A-10Cshow another fiber optic inner housing sub-assembly116that includes a bayonet locking mechanism including an insertion slot118, a rotation slot120, and a retention slot122for accommodating a ferrule holder, such as ferrule holder34having key portions46and carrying ferrule44. The fiber optic inner housing sub-assembly116also includes a latch structure124that extends along a portion of the insertion slot118into the rotation slot120. As shown byFIGS. 10A and 10B, a ramped surface126of the latch structure124causes the latch structure124to press away from the key portion46during insertion into the rotation slot120. As shown byFIG. 10C, the ramped surface126then obstructs the rotation slot120to impede movement of the key portion46out of the rotation slot120back into the insertion slot118.

FIGS. 11A-11Cshow another fiber optic inner housing sub-assembly128that includes a bayonet locking mechanism including an insertion slot130, a rotation slot132, and a retention slot134for accommodating a ferrule holder, such as ferrule holder34having key portions46and carrying ferrule44. In this embodiment, a latch structure136on the inner housing sub-assembly128extends within the rotation slot132to obstruct the key portion46from being moved from the rotation slot132to the insertion slot130. As shown byFIGS. 11A and 11B, when the key portion46is inserted into the insertion slot130, the key portion46engages a ramp surface140of a flange138disposed on the end of the latch structure136. The latch structure136is pressed toward a rear of the rotation slot132while the ramp surface140guides and rotates the key portion46into the rotation slot132, where it can then be rotated toward the retention slot134and released. However, as shown byFIG. 11C, when the key portion46is rotated back toward the insertion slot130, the key portion46engages a side surface142of flange138and is prevented from rotating further. Thus, the flange138of the latch structure136permits movement of the key portion46into the rotation slot132for assembly while preventing removal of the key portion46from the rotation slot132into the insertion slot130, thereby preventing accidental disassembly.