Abstract:
A connector boot for attachment to a flanged BTW-LC connector has extending at an angle therefrom a trigger member. The trigger on the boot acts as an anti-snag device and makes removal of the connector easier. The boot has a bore extending therethrough having an undercut portion for gripping the connector flange, and at least one key in the bore for mating with slots in the flange of the connector for preventing the boot and trigger from turning relative to the connector. In an embodiment of the invention, a second boot parallel to the first boot is joined thereto by a web, and a trigger member extends from the web at an angle to the boots.

Description:
FIELD OF THE INVENTION 
     The present invention relates to optical fiber connectors and, more particularly, to a buffer adapter, also known as the boot, of an optical fiber connector which provides the connector with anti-snagging characteristics and enables the polarity of an optical fiber cable terminated by the connector to be ascertained. 
     BACKGROUND OF THE INVENTION 
     In networks and communication equipment that utilize a high count of optical fibers, such as with a dense wavelength division multiplexer (DWDM), it is frequently a nuisance and time consuming to de-tangle the optical connectors for desirable proper order and illustration, and to ensure DWDM operation, it is important to ensure that the 40 output fibers can also be organized, for example, in order of increased wavelengths, and detangled without damage to the fibers. An increasingly used connector for the purpose of determining fibers on DWDMs is known as the behind-the-wall (BTW) version of the LC connector. This small-form-factor-connector (SFFC) is an optical connector, such as is shown in U.S. Pat. No. 5,719,977 which discloses a BTW optical fiber connector for terminating a cable containing a buffered optical fiber. Each optical fiber is held within a fiber-holding assembly comprising a ferrule and a spring-loaded base member. The fiber-holding assemblies are contained within a common housing that is formed to include a flexible molded plastic latching arm member for interlocking with a mating receptacle or adapter. In high-density applications it is possible to have the latch “fish-hook” other connectors which become difficult to separate and organize. 
     Similarly, it can be important that when only a pair of transmit and receive optical fibers are to be connected to another pair of transmit and receive optical fibers, the correct optical fibers of each of the pairs are connected together in a duplex format, or optically coupled at their ends. Otherwise, an end of a transmit optical fiber of one pair may be connected to an end of a receive optical fiber of the other pair, which, for obvious reasons, is unacceptable. Properly orienting the optical fibers in this duplex manner ensures that the optical fibers are connected with the proper polarity. 
     Duplex optical connectors have been utilized in the communications industry to couple two simplex optical fibers together in a duplex arrangement to allow both optical fibers to be simultaneously connected to ports located on communication equipment or to an adapter that connects pairs of optical fibers together. For example, U.S. Pat. No. 4,787,706 discloses a duplex optical fiber connector for terminating a cable containing a pair of buffered optical fibers. The optical fibers are held within fiber-holding assemblies which are contained within a common housing that is formed to include two flexible molded plastic side arm members for interlocking with a mating receptacle. The housing includes details that can be used to ensure that when the optical fiber connector is connected with another optical fiber connector, the connection is made with the properly polarity. 
     U.S. Pat. No. 5,579,425 (hereinafter the &#39;425 patent) also discloses an optical fiber duplex connector which is constructed by joining together a pair of simplex connectors with a plastic clip. The plastic clip has information thereon, such as the letters A and B, that may be utilized by a user to identify the correct polarization of the duplex connector with respect to an adapter (not shown) into which it is plugged. 
     Although the plastic clip disclosed in the &#39;425 patent is suitable for use with the type of simplex connectors shown, which are normally connected to the front side of a connector receptacle or adapter, this clip is generally not suitable for use with behind-the-wall (BTW) connectors. BTW connectors which typically use buffered fibers are connected on the back side, commonly referred to as the junior side, of the receptacle or adapter where there is typically very little room. The confined area dictates that the simplex connectors and the boots associated therewith generally be shorter in length than the boots of the cables that are used with the simplex connectors in front side mounting configurations. 
     On the front side of the connector receptacle or adapter, there is generally plenty of space for the length of the connector which usually is for jumper cordage and the boot, which is also referred to as a cable support, and hence is not an issue. Therefore, the plastic clip disclosed in &#39;425 patent, which connects to the housing of the connectors is suitable for use in this type of environment since the lengths of the housings normally are sufficiently long to accommodate connection with the clip at locations near the back ends of the housings. However, this generally is not true with respect to connectors used in BTW configurations. 
     It is important that the simplex or duplex orientation is maintained, i.e, each connector not be allowed to rotate on fiber axis, so that the trigger on the boot is in the proper orientation to interact with the latch. Internal keys added to the boot that fit into existing key-slots in the extender cap accomplish this. These key-slots are provided for inspection of proper orientation of the extender cap in the plug housing. 
     In BTW mounting configurations, the connectors that terminate the ends of the receive and transmit optical fibers must be connected to the receive and transmit ports located in the junior side of the receptacle or adapter. Therefore, the receive and transmit optical fibers must be correctly polarized on the junior side of the housing in the same manner in which the receive and transmit optical fibers must be correctly polarized on the front side of the receptacle or adapter. However, currently there is no aid for assisting a user or technician in determining the polarity of the optical fibers connected on the junior side. Therefore, once the transmit and receive optical fibers have been connected to the ports on the junior side, if a user removes one or both of the optical fibers from their respective ports, the user must somehow keep track of which simplex connector is to be connected to which port in order to ensure that the connectors are properly polarized when they are re-connected to the transmit and receive ports. 
     It would be desirable to provide a duplex boot that converts two simplex connectors into a duplex connector for use in case where there is very little room to work with the connectors and/or in cases where the housings of the connectors are too short to enable the housings to be coupled together to form a duplex connector. For example, once the connector has been inserted into an associated adapter or receptacle, most of the body of the connector is contained within the adapter or receptacle and is generally of insufficient length to enable a duplex yoke to be attached thereto for the purpose of clipping two of the connectors together to form a duplex connector. 
     Accordingly, a need exists for simplex and duplex boots that are capable of providing an anti-snag mechanism that prevents the simplex or duplex connectors from fish-hooking when the connectors are being removed from a connection location, and a means to prevent rotation of the connector on the fiber axis. Additionally, a need exists to join two simplex connectors together to form a duplex connector, which is suitable for use with connectors used in BTW configurations, and which helps a user to determine the polarity of the connectors easily. 
     SUMMARY OF THE INVENTION 
     The present invention is an anti-snag boot that attaches to the extender cap of an optical fiber BTW simplex connector to provide the connector with anti-snagging characteristics and/or to enable the polarity of an optical fiber cable terminated by the connector to be ascertained. The device generally is a boot having internal keys that are adapted to be received in the key-slots of the extender cap and prevent rotation of the connector within the boot of an optical fiber simplex or duplex connectors. The boot has a trigger thereon that is in contact with the latch of the simplex connector when the simplex connector is held in the clip body. When a user depresses the trigger, the trigger depresses the latch and causes the simplex connector to be decoupled from an adapter or receptacle. The trigger prevents the latch from snagging on objects, or “fish-hooking”, when the simplex connector is being moved. 
     In accordance with a first embodiment, the boot is adapted to receive and grip the outer surface of the extender cap of a single simplex connector. A generally cylindrical bore is formed in the boot and the inner surface of the bore contains keys which are adapted to interact with existing key-slots of the extender caps. A cable can be passed through the boot prior to assembly of the connector. The boot is aligned and attached to a simplex connector, and then the trigger is available when it is desired to couple or decouple the connector from the receptacle or adapter. The boot has a trigger thereon that is in contact with the latch of the simplex connector when the simplex connector is held by the boot. The trigger allows a user to decouple the connector from an adapter or receptacle and provides the connector with the aforementioned anti-snagging feature. 
     In accordance with another embodiment, the device is a duplex boot that comprises a trigger that is adapted to receive and interact with the latch of the connector housing, that can also contain a web to create a duplex boot from a pair of simplex connectors both to hold the simplex connectors in close spatial proximity to one another to thereby form a duplex connector. The trigger and web are made integral with two or more boots to form a unitary structure. Slots are formed in the extender cap which interact with internal keys provided in the boots to provide an anti-rotation feature. During assembly of the connectors, cables can be passed through the boots so they can be later attached to (a pair of) simplex connectors when the simplex connectors are coupled to or decoupled from a receptacle or adapter. The duplex boot has markings thereon, which preferably are located on the trigger, that enable the polarity of the cables held in the connectors to be easily ascertained. 
    
    
     These and other features and advantages of the present invention will become apparent from the following description, drawings and claims. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a prior arrangement for converting a pair of simplex connectors to a duplex connector; 
     FIG. 2 is a partially exploded perspective view of another arrangement for connecting a pair of simplex connectors to a duplex connector; 
     FIG. 3 is a perspective view of a simplex BTW (behind-the-wall) connector with which the present invention is used; 
     FIGS. 4 a  through  4   c  are perspective views of the boot of the invention for use with the connector of FIG. 3; 
     FIG. 5 is a partially exploded perspective view of the boot of FIGS. 4 a  through  4   c  and the connector of FIG. 3; 
     FIG. 6 is a cross sectional view of the assembled elements of FIG. 5 as mounted in a receptacle; 
     FIGS. 7 a  and  7   b  are an end view and a cross sectional view along the line I—I respectively of the boot of the invention; 
     FIGS. 8 a  through  8   d  are several views of the boot of the invention and embodied in a duplex arrangement; and 
     FIG. 9 is a partially exploded perspective view of the duplex combination of boot and connectors as mounted in a duplex receptacle or one side of a duplex adapter. 
    
    
     DETAILED DESCRIPTION 
     In FIG. 1 there is shown the arrangement of two simplex connectors  11  and  12  with the adapter clip  13  for creating a duplex connector, as disclosed in the previously discussed U.S. Pat. No. 5,579,425 (hereinafter the &#39;425 patent). The duplex connector is constructed by joining simplex connectors  11  and  12  equipped with elongated boots  15  with plastic clip  13  by means of pins  14  projecting from a planar portion  16  of clip  13  which fit into holes  17  in the sides of each of connectors  11  and  12 . Clip  13  is equipped with a trigger  20  which actuates trigger  21  which, in turn, actuate latches  22 . As previously pointed out, clip  13  is generally not suitable for use with behind-the-wall (BTW) connectors, where space is at a minimum. 
     FIG. 2 illustrates another prior art duplex connector arrangement comprising two simplex connectors  23  and  24  which are clipped together to form a duplex connector by a yoke  27  which has a trigger  28  for actuating latching arms  29  and having boots  26 . Both the triggers  20  and  28  provide the anti-snag protection that is desired. 
     The housing of connectors  23  and  24  require back portions  31 , as do connectors  11  and  12  of the FIG. 1 arrangement which contain metal inserts for side loading capability which is a desideratum for front side connectors, as the connectors of FIGS. 1 and 2 are. However, such arrangements as shown in FIGS. 1 and 2 are not suitable for BTW mounting. For BTW mounting, metal inserts are not required, hence the back portion  31  of the connector body can be replaced by an extender cap which makes the connector substantially shorter. 
     In FIG. 3 there is shown a connector  33  suitable for BTW use, which comprises a body portion  34  having an extender cap  36  which has a short flanged portion  37  extending therefrom. Flanged portion  37  has key slots  38  therein (best seen in FIG. 5) which provide for inspection of proper orientation of the extender cap  36  in the plug housing  34 . Body portion  34  has a latching arm  39  extending at an angle therefrom which functions to latch connector  33  in place within an adapter (not shown) or other connector receiving member. The front portion  41  of body portion  34  has a fiber containing ferrule (not shown) extending therefrom which, as shown in FIG. 3, is protected by a protective plug  42 , which is removed when a connection is to be made. The ferrule is extended by a barrel or tube  51 ′ to facilitate installation of adhesives and the fiber. The overall length of connector  33  is substantially less than that of  11 ,  12 ,  23 , and  24  shown in FIGS. 1 and 2, thereby making it more suitable as a BTW connector. 
     As was pointed out in the foregoing, the abbreviated length of the BTW plug presents some difficulty in introducing an anti-snag or anti-fish hook arrangement inasmuch as there generally is not room for a trigger to be formed on the back end of connector  33 , extender cap  36  being too short. In FIGS. 4 a  through  4   c  there are shown various views of the boot  43  of the present invention, which provides an anti-snag feature. Boot  43  comprises elongated body having a large diameter portion  44  having a bore  46  therein for fitting the boot  43  over the flanged portion  37  of extender cap  36 , a tapered portion over section  47  which resists side pulling and ensures a minimum bend radius for the optical fiber, and a reduced diameter portion  48  through which the fiber passes and which protects the buffered fiber from kinking. Between bore  46  and a reduced diameter portion  45  is a circular tapered cavity  40 , and there is created a shoulder from which a pair of keys  50  extend, toward the front or connector end of the boot as best seen in FIG. 7 b . Boot  43  is preferably made from a suitable material, such as flexible PVC or TPR, which is resilient or flexible, but sufficiently stiff to resist heavy side loads. In order to create an anti-snag configuration, boot  43  has extending at an angle therefrom a cantilevered trigger  49 , the use of which is more clearly shown in FIGS. 5 and 6. In FIG. 5, connector  33  and boot  43  are shown arrayed, but not connected to each other, on a buffered fiber  55 . It is to be understood that other than buffered fiber may comprise member  55 , which has been mounted in barrel assembly tube  51 ′. Generically, the term “cable” will be used hereinafter. Boot  43  is oriented relative to connector  33  such that, when they are connected, keys  50  fit within keyways  38 . In addition, trigger  49  is oriented relative to keyways  38  such that its free end overlies the end of latching arm  39 , as best seen in FIG. 6, thereby reducing the damages of snagging or fish hooking. In FIG. 6 the assembled connector-boot arrangement is shown mounted in a sectional view showing a receptacle or one-half of an adapter  52  (the alignment and other half of the adapter not shown). FIG. 6 also shows the location and orientation of the previously mentioned ferrule  51 . 
     FIGS. 7 a  and  7   b  illustrate the configuration of the boot and illustrate the arrangement of the bores  45  and  46  and location of the keys  50 . It can be seen that bore  46  has a beveled undercut cavity  40  into which flange portion  37  of extender cap  36  fits and is gripped thereby, as seen in FIG.  6 . 
     From the foregoing it can be seen that the boot  43  of the invention in its simplex configuration provides anti-snag protection without requiring additional connector length as in the structures of FIGS. 1 and 2, and facilitates removal of the connector from the adapter and, additionally, in the case of the duplex connector, insures correct polarization of the optical fiber and prevention of rotation of the connector relative to the fiber axis. 
     The principles of the invention as illustrated in the foregoing are readily adaptable to use in a duplex arrangement. In FIGS. 8 a  and  8   b  there is shown a duplex boot arrangement  52  wherein first and second boots  53  and  54  are joined together in spaced relationship by a web  56  which has extending therefrom a trigger member  57 . Inasmuch as the individual boots  53  and  54  are substantially identical to the simplex boot  43  described in the foregoing, corresponding parts have been given the same reference numerals. The duplex structure  52  can be in the form of a unitary molded member, or web  57  and trigger  57  may be in the form of a clip mounted on the boots  53  and  54 . FIGS. 8 c  and  8   d  are, respectively, an end view and a top plan view of the duplex connector arrangement. It is possible that more than a two connectors, i.e., duplex, assembly might be required in which case the arrangement of FIGS. 8 a  through  8   d  can be expanded to accommodate more than two connectors, preferably in a unitary form, but by means of clips if desired. It can be appreciated that, thus joined, the connectors and the boots will not rotate relative to each other, thus insuring correct polarization. 
     FIG. 9 illustrates, in perspective, the relationship of the duplex arrangement  52  of FIGS. 8 a  through  8   c  with a pair of BTW connectors  58  and  59  (buffered fibers not shown) mounted in a receptacle or half of an adapter  61 . As was the case in the simplex arrangement, each connector  58  and  59  has a latching arm  62  and  63 , respectively which are adapted to be actuated by trigger  57 , the free end of which overlies them (see FIG.  6 ). The numerous advantages listed in the discussion of the simplex arrangement are also realized in the duplex (or greater) arrangement. 
     It is to be understood that the various features of the present invention are amenable to inclusion in other connector-boot arrangements, and that other modifications or adaptations might occur to those skilled in the art. All such variations, modifications, or adaptations are intended to be included herein as being within the scope of the present invention as set forth in the claims. Further, in the claims hereafter, the corresponding structures, materials, acts, and equivalents of all means or step plus function elements are intended to include any structure, material, or acts for performing the functions in combination with other elements as specifically claimed.