Patent Description:
The present invention relates to optical connectors in general and, more particularly, to optical connectors having forward-biasing projections.

Demand for bandwidth by enterprises and individual consumers continues to rise exponentially. To meet this demand, fiber optics have become the standard cabling medium. Fiber optics relies on individual optical fibers of glass or polymers that are on the order of <NUM> microns in diameter. Data centers use high-density cabling, with individual fiber optic cables containing one or more optical fibers. Typically, in these high-density environments, MPO (multiple push on) connectors are used for connecting multiple optical fibers from a single multi-fiber cable. Fiber counts may be, for example, <NUM>, <NUM>, <NUM>, or <NUM> fibers. MPO optical connectors are subject to high side-loading forces. These side -loading forces occur at equipment connection points due to the cables being bent in a downward direction. A side-loaded fiber optic cable is depicted in <FIG>.

Further, current optical connectors typically use many small components assembled into a single connector. An example of a prior art connector is depicted in <FIG> (exploded view) and FIG. IB (assembled). Prior art connector <NUM> includes a dust cap <NUM> and an outer housing <NUM> that surrounds an inner housing <NUM> and employs micro springs <NUM> to bias the outer housing towards the distal (connection direction) end of the connector. From the proximal end, backpost <NUM>, spring <NUM>, pin keeper <NUM>, guide pins <NUM>, optical ferrule <NUM> and ferrule boot <NUM> are assembled into the inner housing <NUM>. Crimp ring <NUM> and boot <NUM> are assembled over the end of an optical cable. Many designs use components that "snap fit" into each other during assembly. For example, in the connector of <FIG>, the backpost <NUM> snap fits into inner housing <NUM>. Therefore, not only the side -loading stress during use but the stress of assembly may cause these components to break. Further mechanical stress is applied to the components during testing, such as in <FIG> (the arrow indicating the direction of loading), providing another occasion for components of an optical connector to fail.

Current optical connectors feature a backpost, shown in <FIG> and <FIG>. The backpost includes a pair of legs that may be prone to breaking at region <NUM> under side loads, as seen in the photograph of <FIG>. Typically, the backpost is fabricated from a polymeric component and is configured to snap fit into the connector housing. Breaking of a backpost leg may occur at the point where the backpost latches into the housing, as depicted by the arrow in <FIG> or at the corner of the backpost leg, where it meets the backpost base. The breaking of a connector may interrupt traffic carried by the optical fiber and requires a new connector to be spliced to the end of the fiber, a time-consuming process. Therefore, there is a need in the art for optical connectors that can withstand strong side-loading forces.

Fiber optic connectors typically feature an outer housing that is resiliently- biased in a forward direction by a pair of housing micro-springs, as seen in <FIG> and <FIG>. Manufacture of the connector is complicated by the presence of these springs which must be carefully assembled between the main body and the outer housing. Further, the springs may fail by being bent or by having adjacent spring coils entangle one another. Thus, there is a need in the art for fiber optic connectors that do not include micro-springs, to ease assembly and reduce potential connector failure.

<CIT> discloses an optical connector according to the preamble of claim <NUM>. The object of the invention is achieved by an optical connector with the features of claim <NUM>. An optical connector is provided having a ferrule configured to house one or more optical fibers. An inner housing is provided to hold the ferrule and has a distal end in a connection direction and a proximal end in a cable direction. An outer housing at least partially surrounds the inner housing. One or more resilient forward biasing projections extend from the outer housing for biasing the outer housing towards the distal end of the inner housing. The one or more resilient forward biasing projections is/are integrally formed with the outer housing.

This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only and is not intended to limit the scope.

As used in this document, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term "comprising" means "including, but not limited to.

The following terms shall have, for the purposes of this application, the respective meanings set forth below. A connector, as used herein, refers to a device and/or components thereof that connects a first module or cable to a second module or cable. The connector may be configured for fiber optic transmission or electrical signal transmission. The connector may be any suitable type now known or later developed, such as, for example, a ferrule connector (FC), a fiber distributed data interface (FDDI) connector, an LC connector, a mechanical transfer (MT) connector, a square connector (SC) connector, an SC duplex connector, an MPO connector, or a straight tip (ST) connector. The connector may generally be defined by a connector housing body. In some embodiments, the housing body may incorporate any or all of the components described herein.

A "fiber optic cable" or an "optical cable" refers to a cable containing one or more optical fibers for conducting optical signals in beams of light. The optical fibers can be constructed from any suitable transparent material, including glass, fiberglass, and plastic. The cable can include a jacket or sheathing material surrounding the optical fibers. In addition, the cable can be connected to a connector on one end or on both ends of the cable. As used herein, the term "optical fiber" is intended to apply to all types of single mode and multi-mode light waveguides, including one or more bare optical fibers, coated optical fibers, loose-tube optical fibers, tight-buffered optical fibers, ribbonized optical fibers, bend performance optical fibers, bend insensitive optical fibers, nanostructured optical fibers or any other expedient for transmitting light signals.

In describing the various embodiments, the term "distal," when used with an optical connector, refers to the connection direction of the optical connector. The term "proximal" refers to the cable direction of an optical connector. When used in connection with other parts, the term "proximal" refers to a location closest to a point of attachment of the part, while "distal" refers to a location furthest from a point of attachment of the part.

<FIG> respectively depict an isometric view and an exploded view of an optical connector <NUM> according to an embodiment. The connector <NUM> may include a one-piece housing-backpost <NUM> configured to hold a ferrule <NUM>. Note that the present embodiment may also be employed with the conventional two-piece inner housing and separate backpost combination of <FIG>. The specification and claims use the expression "inner housing" generically to include either the one-piece housing-backpost or the two-piece housing plus backpost - the expression "inner" is used to differentiate the outer housing from the "inner" housing which the outer housing at least partially surrounds. Ferrule <NUM> may be a single-fiber or a multiple- fiber ferrule, urged towards a distal (connection) end of the housing by biasing member <NUM>. It is depicted as a multiple-fiber MPO connector but it is understood that it could also be a single fiber connector or any of the connectors described above.

The optical connector <NUM> may further include a pin retainer <NUM> configured to receive a pair of guide pin 303a, 303b that extend into the ferrule <NUM>. Depending on whether the connector is configured as a male, female, or reconfigurable connector, the guide pins may extend through the ferrule or the ferrule will have receiving apertures to accommodate guide pins from a mating connector. The biasing member <NUM>, depicted in this embodiment as a spring, may be disposed between the housing <NUM> and the pin keeper/retainer <NUM> to bias the ferrule <NUM> distally within the housing <NUM>. Such biasing provides a biased mating of ferrule ends when the connector <NUM> is mated in an adapter or other connection to thereby hold the mated ferrule ends in contact with one another. An optional ferrule boot <NUM> is provided for fiber organization as the fibers extend into ferrule <NUM>.

In use, a fiber optic cable is attached to the proximal end of connector <NUM>, extending from a cable boot <NUM>. The fiber optic cable may be retained with the housing <NUM> by means of a crimp ring <NUM>, or any other type of detainment connector. A connector such as crimp ring <NUM> may be crimped to the inner housing as well as to a cable sheathing (e.g., aramid fiber sheathing) of the cable to thereby prevent the cable from being pulled away from the inner housing. The cable boot <NUM> is positioned over the crimped connection, providing support to an optical cable extending therethrough. The ferrule boot may be shaped to include an angle for connectors that will be subject to side loading to orient the cable <NUM> degrees from the connection direction.

Various optional accessories may be added to the basic optical connector. A polarity-changing key <NUM> that snap fits over inner housing <NUM> may be added to permit a user to change polarity of the optical connector, to be discussed in detail in connection with <FIG>, below. An optional dust cap <NUM> may also be added to fit over the distal end of connector to protect the ferrule and the optical fibers contained therein when the connector is not connected to a mating connector or other device.

The connector <NUM> may further include a displaceable outer housing <NUM> that is at least partially surrounding the inner housing <NUM> and slidably disposed about the inner housing <NUM> (and, optionally, key <NUM>) adjacent the distal end of the connector <NUM>.

<FIG> provide a detailed comparison between the optical connector <NUM> of the present embodiment and the prior art connector of <FIG>. As seen in <FIG>, the outer housing <NUM> of the optical connector <NUM> of the present embodiment has a resilient forward biasing projection <NUM> integrally formed with and extending from the outer housing for biasing the outer housing towards the distal end of the inner housing <NUM>. In contrast to the prior art connector as shown in <FIG>, wherein a pair of micro-springs 103a and 103b are used for biasing an outer housing <NUM> towards the distal end of a main body <NUM>, the optical connector <NUM> of the present embodiment does not include micro-springs. Therefore, assembly is simplified and potential connector failure is reduced.

<FIG> shows the optical connector <NUM> according to the present embodiment after assembly. As seen in <FIG>, the resilient forward biasing projection <NUM> may be a bendable arm integrally formed with and protruding from the outer housing <NUM>. The bendable arm <NUM> is configured to contact a flange <NUM> of the inner housing <NUM>. When the outer housing <NUM> is pulled towards the proximal (cable) direction along the inner housing <NUM>, the bendable arm <NUM> is bent. The bent arm <NUM> then exerts a restoring force to bias the outer housing back towards the distal end of the inner housing.

<FIG> shows an optical connector according to a further embodiment. As seen in <FIG>, a bendable arm <NUM> is integrally formed and protruding from an outer housing <NUM>. The bendable arm <NUM> is configured to contact a flange <NUM> of an inner housing <NUM>. In addition to the primary bendable arm <NUM>, the optical connector <NUM> further includes an auxiliary bendable arm 521a protruding from the outer housing <NUM> and configured to act on the primary bendable arm <NUM> to enhance the elastic force for biasing the outer housing <NUM> towards the distal end of the inner housing <NUM>. Alternatively, arm 521a may be offset and itself act on flange <NUM> (not shown), enhancing the elastic force that distally biases the outer housing.

<FIG> shows an optical connector according to a further embodiment. In the embodiment of <FIG> there are two separate bendable arms <NUM>, 521a protruding from the outer housing <NUM> and configured to independently bias outer housing <NUM> towards distal end of inner housing <NUM>. That is, the bendable arms <NUM>, 521a do not contact one another in either an unbiased or biased position. <FIG> is an enlarged view of the arms (<NUM>, 521a) in an activated position, that is, as the outer housing is being retracted towards the proximal direction; the arms <NUM>, 521a do not touch each other as they are compressed. <FIG> is an enlarged view showing a gap 521c between arms <NUM> and 521a even when they are fully compressed when the outer housing is fully retracted.

<FIG> depicts another embodiment of bendable arms (<NUM>, 521a) that do not touch as the outer housing is retracted and are likewise configured to independently bias outer housing <NUM> towards distal end of inner housing <NUM>. <FIG> is an enlarged view of a gap 521c between the arms <NUM>, 521a as the outer housing is retracted in the proximal directions, operation. Without departing from the scope of the invention, one, two or more bendable arms can be used to perform biasing as described above.

Note that many variations of bendable arms may be used in the disclosed connectors including more than two bendable arms. Note also that the same configurations depicted in the above FIGS. may be present as well on the reverse side of the connector to provide additional spring force biasing the outer connector in the distal direction.

<FIG> show an optical connector <NUM> related to embodiments, not part of the claimed invention, wherein the resilient forward biasing projection is extending from the inner housing. As seen in <FIG>, the optical connector <NUM> includes an inner housing <NUM> having a bendable arm <NUM> integrally formed with and protruding from the inner housing. As shown in <FIG>, the bendable arm <NUM> of the inner housing <NUM> is configured to contact a surface <NUM> at the end of the outer housing <NUM> after assembling. In <FIG>, the outer housing has been retracted/pulled towards the proximal (cable) direction, compressing the bendable arm <NUM>. In <FIG>, the bendable arm exerts a restoring force against surface outer housing surface <NUM> to bias the outer housing towards the distal end of the inner housing. Although not shown in <FIG>, multiple arms similar to those depicted in <FIG> could also be used with the inner housing to bias the outer housing towards the distal direction.

<FIG> show an optical connector <NUM> according to a further embodiment part of the claimed invention. As shown in <FIG>, the optical connector <NUM> has a resilient forward-biasing projection in the form of one or more ramps <NUM> extending at the proximal end of inner housing <NUM>. Cooperating with the ramps <NUM> are one or more flexing wings <NUM> formed at the proximal end of an outer housing <NUM>. As shown in <FIG>, when the outer housing is retracted in the proximal direction, the flexing wings <NUM> of the outer housing extend outwardly as they are pushed open by the ramps <NUM> of the inner housing. <FIG> shows a cross-sectional view of the optical connector <NUM> when the outer housing is at its forwardly-biased position. <FIG> shows a cross- sectional view of the optical connector <NUM> when the outer housing is retracted towards the proximal direction. It can be seen that the flexing wings <NUM> are deformed outwardly; this deformation creates a restoring force against the ramps <NUM> to bias the outer housing towards the distal end of the inner housing <NUM>.

<FIG> show an optical connector <NUM> related to embodiments not part of the claimed invention. As seen in <FIG>, the optical connector <NUM> may include a resilient forward- biasing projection in the form of one or more flexing wedges <NUM> integrally formed at the proximal end of an inner housing <NUM>. Cooperating with the flexing wedges is a rigid edge <NUM> of outer housing <NUM> at its proximal end. As shown in <FIG>, when the outer housing is retracted towards the proximal direction, the flexing wedges <NUM> of the inner housing bend inwardly upon contacting the edge <NUM> of the outer housing.

<FIG> shows a cross-sectional view of the optical connector <NUM> when the outer housing is at its forwardly-biased position while <FIG> shows a cross- sectional view of the optical connector <NUM> when the outer housing is retracted in the proximal direction. It can be seen that the flexing wedges <NUM> are deformed inwardly, toward the interior of the inner housing. In this configuration, a restoring force is exerted against the outer housing edge <NUM> to bias the outer housing towards the distal end of the inner housing.

<FIG> depict a prior art connector having a separate backpost and housing compared to <FIG> showing a connector related to the embodiments. As seen in <FIG>, the prior art connector with a separate backpost assembles components from a proximal (cable) end direction, as shown by the arrow direction, while the connector of <FIG> (substantially similar to <FIG>) assembles components from a distal (connection direction) end, as shown by the arrow. The two-piece housing/backpost configuration of <FIG> is replaced by the one-piece housing-backpost component <NUM> of <FIG> IB.

Advantageously, forming an integrated, one-piece housing-backpost permits fabrication of the housing-backpost from a variety of materials including polymers, reinforced polymers, ceramics, and metals. In particular, the housing-backpost may be fabricated from die cast metal to increase component strength.

An enlarged view of the one-piece housing-backpost is depicted in <FIG>. The one-piece housing-backpost <NUM> (substantially similar to housing-backpost <NUM>) includes a large, approximately central distal aperture <NUM> for receiving the ferrule spring <NUM> and the ferrule <NUM>. A first sidewall <NUM> is positioned along the top of housing-backpost <NUM> while a second sidewall is positioned along the bottom of housing-backpost <NUM>. Positioned in the first sidewall is one or more resiliently- deformable ferrule -retaining protrusions <NUM> extending inwardly from the sidewall to engage the corresponding stepped portion of the ferrule. In the perspective view of <FIG>, only the external portion of the protrusion is visible; <FIG> depicts a cross-sectional view of the housing-backpost where the protruding portion of the protrusion <NUM> is best seen. By being formed as a cutout in the housing-backpost, the protrusion <NUM> can flex outwardly during insertion of the ferrule, accommodating the stepped portion of the ferrule, to be discussed in connection with <FIG> below.

The one-piece housing-backpost <NUM> further includes guide projections <NUM> and projection <NUM> for engaging a polarity-changing key, to be discussed in further detail below. A ridged, approximately cylindrical portion <NUM> extends from a collar <NUM> to accommodate a crimp ring <NUM> during connector assembly.

Turning to <FIG>, the protrusion <NUM> may be clearly seen in the cross-sectional views of <NUM> A (unassembled), 13B (as ferrule enters the housing-backpost), and 13C (with ferrule assembled). As seen in <FIG>, the protrusion <NUM> flexes/deforms outwardly as the ferrule stepped portion <NUM> is inserted from the distal end into the housing-backpost <NUM>. After the ferrule is seated in the housing- backpost <NUM>, the protrusion <NUM> returns to its initial position, as shown in <FIG>, preventing forward movement of the ferrule as it butts against the stepped portion <NUM> to maintain the ferrule <NUM> in the housing-backpost.

To further assist in retaining the ferrule <NUM> within the housing-backpost <NUM>, the pin keeper of <FIG> may optionally be provided. As compared with a conventional pin keeper, <FIG>, the pin keeper of <FIG> includes a pin keeper main body and a top arm <NUM> and bottom arm <NUM> respectively extending from a main body <NUM>. As seen in the assembled cross-sectional view of <FIG>, top arm <NUM> and bottom arm <NUM> retain the ferrule <NUM> in the one-piece housing- backpost <NUM>, preventing the ferrule from rotating and detaching from the protrusion <NUM>.

In an alternative connector related to the embodiments, a retaining clip may be provided to maintain the ferrule in a seated position within a one-piece housing-backpost <NUM>. As seen in <FIG>, a clip <NUM> is positioned in the distal end of the housing-backpost to retain the ferrule in the housing/backpost. The clip <NUM> includes one or more protrusions <NUM>. These protrusions <NUM> are retained within one or more sidewall apertures <NUM> of the housing-backpost <NUM>. Within the clip <NUM>, angled sidewalls <NUM> (shown in <FIG>) narrow from the distal end towards the proximal end that contacts the ferrule stepped portion <NUM> to retain the ferrule within the housing- backpost <NUM>.

<FIG> and <FIG> depict a further connector related to the embodiments for maintaining a ferrule <NUM> within a one-piece housing-backpost <NUM> configured to receive a ferrule spring <NUM> , a pin keeper <NUM> and the ferrule <NUM> from the distal end. The pin keeper includes a main body <NUM> and top and bottom arms <NUM> respectively extending from the main body <NUM> (<FIG>). The top and bottom arms <NUM> include ferrule - retaining projections <NUM> (<FIG>) configured to grip the ferrule <NUM> adjacent the stepped portion <NUM> (<FIG>). The pin keeper main body <NUM> includes a first pair of deformable projections <NUM> positioned on side regions of pin keeper <NUM>. Optionally, a second pair of deformable projections <NUM> (<FIG> may be positioned on the top and bottom of pin keeper <NUM>. The deformable projections <NUM>, <NUM> engage in mating apertures <NUM>, <NUM> (<FIG>) in the housing-backpost <NUM> to retain the pin keeper <NUM> in the housing-backpost <NUM>. By engaging the projections <NUM>, <NUM> from the pin keeper <NUM> in the housing-backpost aperture <NUM>, <NUM>, the spring force from ferrule spring <NUM> is absorbed by the housing-backpost, preventing the ferrule <NUM> from being pushed out of the housing-backpost <NUM>.

<FIG> depict a removable polarity-changing key <NUM> that may be used with all embodiments of the present disclosure. As a result of using preterminated fiber assemblies, the issue of maintaining polarity in parallel fiber-optic links is becoming increasingly important. Polarity maintains proper continuity between transmitting and receiving elements in an optical network. In order to make sure that connectors are mated correctly with a receiving element such as an adapter or a transceiver, both the connector and the receiving element typically include keying features that permit the connector to be mated with the receiving element in generally only one mating configuration. The present embodiment uses a removable polarity-changing key in order to facilitate changing a connector from one polarity configuration to a configuration of the opposite polarity. The polarity-changing key <NUM> and its mating elements may be selected from any of those disclosed in <CIT>.

As seen in <FIG>, polarity-changing key <NUM> includes an aperture <NUM> and a gripping portion <NUM>. To facilitate user manipulation of the key, one or more ridges may be formed in the gripping portion <NUM>, as shown. The housing-backpost includes a key-engagement projection <NUM> over which the key <NUM> may be inserted to engage the projection within the key aperture <NUM>. The projection <NUM> may be tapered outwardly away from the housing-backpost <NUM> to facilitate movement of the key <NUM> over the key projection <NUM>. Guide projections <NUM> are spaced at approximately the width of the key <NUM> on the housing backpost to guide the key towards the projection <NUM> as the key is slid in from the distal end as shown by the arrow in <FIG>. As seen in <FIG>, the key <NUM> slides between the guide projections <NUM> to engage the key projection <NUM> (<FIG>).

Turning to the cross-sectional views of <FIG>, the polarity-changing key <NUM> is shown engaged on projection <NUM> in <FIG>. For removal of the polarity-changing key <NUM>, the key projection <NUM> is depressed in <FIG> and the key slides off housing-backpost <NUM> in the distal direction is shown by the arrow. A key projection <NUM> and guide projections <NUM> are also provided on the opposite surface of the housing-backpost <NUM>. To reverse the polarity of the connector, the key <NUM> is reinserted via these opposite-surface projections.

In the above detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, within the scope of the invention as defined by the appended claims. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

Claim 1:
Optical connector comprising:
a ferrule (<NUM>) configured to house one or more optical fibers;
an inner housing (<NUM>; <NUM>; <NUM>) configured to hold the ferrule (<NUM>) and having a distal end in a connection direction and a proximal end in a cable direction, the inner housing (<NUM>; <NUM>; <NUM>) having a top and bottom each extending between the distal end and the proximal end;
an outer housing (<NUM>; <NUM>; <NUM>) at least partially surrounding the inner housing (<NUM>; <NUM>; <NUM>); and
a flange (<NUM>) provided on the top or bottom of the inner housing;
characterized by
a resilient biasing projection (<NUM>; <NUM>; <NUM>) extending from the outer housing (<NUM>; <NUM>; <NUM>) and arranged on the same side as the flange to cooperate with the flange to bias the outer housing (<NUM>; <NUM>; <NUM>) towards the distal end of the inner housing (<NUM>; <NUM>; <NUM>) when moving the outer housing towards the proximal end of the inner housing, wherein the resilient biasing projection (<NUM>; <NUM>; <NUM>) is integrally formed with the outer housing (<NUM>; <NUM>; <NUM>).