Patent Document

FIELD OF THE INVENTION 
     The present invention relates generally to methods of attaching lanyards and more specifically to a method and attachment assembly for attaching preformed loops to dust covers. 
     BACKGROUND OF THE INVENTION 
     Dust covers are used to protect connectors in a variety of electrical and optical applications. Dust covers are of particular importance in optical applications. An exposed fiber end may be damaged by adverse environmental hazards, and the accumulation of dust and dirt may impair the optical transmission capabilities of the fiber. Due to the importance of protecting optical fibers, dust covers are often attached to the connector using a lanyard to ensure that they are not lost. The most common method of attaching lanyards to dust covers was to use a wire rope, a metal sleeve and a special tool. At the time of assembling the optical connector and the dust cover, the lanyard was formed into a loop around the dust cover. Then the loop was secured using the metal sleeve and tool. This process was costly and time consuming. Another disadvantage of using this method was that it was difficult for customers to install replacement lanyards. If the lanyard broke, the customer was required to handle small parts, order a special tool and follow detailed installation instructions to form a properly sized loop. Therefore, there is a need for a method of attaching lanyards to dust covers that does not involve using tools. 
     SUMMARY OF INVENTION 
     In accordance with practice of the present invention, a device configured for attaching a preformed loop of a selected internal diameter to the device is provided. The device includes a flange located in a first plane, a groove adjacent the flange and a slot in the flange disposed at an angle to the first plane. The shape of the groove and angle of the slot enable the preformed loop to be guided into the groove by rotation of the loop relative to the structure. The shapes of the flange and the groove substantially prevent unwanted detachment of the preformed loop from the groove. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a semi-schematic side elevational view of a dust cover including a groove and a flange with a slot in it provided in accordance with practice of the present invention; 
     FIG. 2 a  is a semi-schematic elevational view of a wire lanyard including a preformed loop; 
     FIG. 2 b  is a semi-schematic elevational view of a plastic lanyard including a preformed loop. 
     FIGS. 3 a-   3   d  are perspective views illustrating a method of attaching a preformed lanyard to a dust cover provided in accordance with practice of the present invention; 
     FIG. 4 a  is a semi-schematic side elevational view of a dust cover including a groove and a flange with a slot therein; and 
     FIG. 4 b  is an enlarged view of the slot of FIG. 4 a.   
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although detailed illustrative embodiments are disclosed herein, other suitable structures for practicing the invention may be employed and will be apparent to persons of ordinary skill in the art. Consequently, specific structural and functional details disclosed herein are representative only; they merely describe exemplary embodiments of the invention. 
     Turning to FIG. 1, a preferred embodiment of a dust cover  10  provided in accordance with practice of the present invention is illustrated. The structural features of the dust cover  10  that comprise an assembly for enabling the attachment of a preformed lanyard, include a flange  12 , a groove  14  adjacent the flange and a slot  16  through the flange. The slot  16  forms an angle  18 , which is defined relative to the centerline of the dust cover  10 . In one preferred embodiment, the attachment assembly portion of the dust cover is manufactured by lathing a round rod of aluminum. The lathe turns down the diameter of the rod to create the flange  12  and the groove  14  and then a milling machine is used to create the slot  16 . Anodizing the aluminum rod completes the manufacturing process. However, other methods of construction that result in the creation of a groove and a flange with a slot in it can also be used. 
     Turning now to FIG. 2 a  in addition to FIG. 1, there is shown a lanyard  20  with a preformed loop  22  which can be attached to the dust cover  10  by means of the attachment assembly. The lanyard  20  is typically constructed from a flexible nylon covered wire formed into a loop using a crimping sleeve  24 . However, preformed plastic lanyards can also be used. Turning now to FIG. 2 b , an embodiment of a plastic lanyard  20 ′ provided in accordance with practice of the present invention comprising a preformed loop  22 ′ is illustrated. 
     Referring back to FIG. 1, the external surface of the dust cover  10  is preferably cylindrical, however, any shape is appropriate. The flange  12  is preferably a disk at one end of the dust cover possessing a diameter larger than the inside diameter of the preformed loop  22 . However, the flange  12  can be any shape so long as the combination of the flange shape and size prevents the removal of the lanyard  20  without the use of the attachment assembly once it has been attached to the dust cover. The groove  14  is preferably a circular groove around the dust cover comprising a hub with a diameter “d” located adjacent the flange  12 . However, the groove  14  can be any shape so long as its shape can be contained within the preformed loop  22 . The groove  14  is constructed so that the hub diameter “d” is less than the internal diameter of the preformed loop  22 , when it is substantially formed as a circle as shown by the imaginary line  26  in FIG. 2 a.    
     Turning now to FIGS. 3 a - 3   d , a process provided in accordance with practice of the present invention for attaching the preformed loop  22  to the dust cover  10  is illustrated. A portion of the preformed loop  22  is placed in the slot  16 . The dust cover  10  and the preformed loop  22  are then rotated relative to each other and the motion of rotation guides the preformed loop  22  into the groove  14 . The direction of rotation required to attach the preformed loop  22  is as shown in FIGS. 3 a - 3   d.    
     Referring now to FIGS. 3 c  and  3   d , when a single rotation is almost complete, the majority of the preformed loop  22  has been guided into the groove  14  and a small segment remains outside of the groove  14 . As the rotation completes, the portion of the preformed loop  22  remaining outside of the groove  14  disengages from the slot  16  and proceeds into the groove, so that the entire preformed loop  22  is inside the groove  14 . In embodiments that use flexible nylon coated wire lanyards, the preformed loop  22  disengages from the slot  16  and proceeds into the groove  14  because the crimping sleeve creates a loop that is not exactly circular. In embodiments utilizing plastic lanyards, such as the lanyard shown in FIG. 2 b  with circular preformed loops  22 , the elastic properties of the plastic enable the preformed loop  22  to disengage from the slot  16  and proceed into the groove  14 . 
     The preformed loop  22  can be detached by performing the above process in reverse. Due to the fact that the preformed loop  22  must be placed in the slot  16  for detachment to occur, the attachment assembly can be designed to virtually eliminate the possibility that the preformed loop  22  will detach during the regular usage of the dust cover  10 . 
     Referring again to FIG.  1  and FIG. 2 a  in addition to FIGS. 3 a - 3   d , the ability to attach the preformed loop  22  to the dust cover  10  using the dust cover attachment assembly of the present invention is dependent on the angle  18  of the slot  16  relative to the dust cover center line, the width of the slot  16  (shown as “s” in FIG.  1 ), the internal diameter of the preformed loop  22  when it is substantially formed as a circle as shown by the imaginary line  26  of FIG. 2 a , the diameter of the flange  12  (shown as “D” in FIG.  1 ), the width of the flange  12  (shown as “f” in FIG.  1 ), the hub diameter “d” of the groove  14 , the width of the groove  14  (shown as “g” in FIG. 1) and the materials used to construct the dust cover  10  and the lanyard  20 . 
     In one preferred embodiment of the dust cover  10 , it is constructed from anodized aluminum and the preformed loop  22  and lanyard  20  are constructed using nylon coated wire. The angle of the slot  18  is 45°, the width “s” of the slot is 0.065 in, the internal diameter of the preformed loop  22  of the lanyard  22  is 1.0 in, when it is substantially formed as a circle as shown by the imaginary line  26  of FIG. 2 a , the diameter “D” of the flange  12  is 1.2 in, the width “f” of the flange  12  is 0.08 in and the hub diameter “d” of the groove  14  is 0.99 in. 
     Turning now to FIGS. 4 a  and  4   b , in one embodiment of the dust cover  10  of the present invention, the slot  16  has an outside leading edge  30 , an inside leading edge  32 , an outside trailing edge  34  and an inside trailing edge  36 . The outside leading edge  30  and inside trailing edge  36  are rounded. 
     Referring again to FIGS. 1 and 3 a - 3   d  in addition to FIGS. 4 a  and  4   b , decreasing the angle  18  of the slot  16  causes the preformed loop  22  of the lanyard  20  to catch against the outside leading edge  30  and the inside trailing edge  36  of the slot as the lanyard is being guided into groove  14 . Catching of the preformed loop  22  of the lanyard  20  against the edges of the slot  16  can be alleviated by reducing the width “f” of the flange  12 , increasing the width “g” of the groove  14  or decreasing the friction between the attachment assembly and the preformed loop  22 . 
     Increasing the angle of the slot  18  increases the ease with which the preformed loop  22  can be attached to the dust cover  10  using the dust cover attachment assembly provided in accordance with practice of the present invention. However, two problems result when the angle  18  is increased. The first is that the outside leading edge  30  and the inside trailing edge  36  of the slot  16  can cut into the preformed loop  22  as it is being attached to the dust cover  10 , causing the loop  22  to break. A closer inspection of FIG. 4 b  reveals that the outside leading edge  30  and inside trailing edge  36  of the slot  16  are rounded to prevent breakage from occurring. The extent of the required rounding increases as the angle  18  of the of the slot  16  increases. 
     The second problem that arises from increasing the angle and thus increasing rounding is that the rounding increases the width “s” of the slot  16  at its opening into the groove  14 . Increasing the width “s” of the slot  16  opening increases the likelihood that the preformed loop  22  will inadvertently detach from the dust cover  10 , because the greater the slot width “s” the more likely a portion of the preformed loop  22  of the lanyard  20  will enter the slot. Once the preformed loop  22  has entered the slot  22 , then rotation of the preformed loop relative to the attachment assembly can result in the detachment of the preformed loop from the attachment assembly. For example, the preformed loop  22  can inadvertently detach if a portion of the preformed loop proceeds into the slot  16  and then the preformed loop is rotated relative to the dust cover  10  in a direction opposite to the direction of rotation shown in FIGS. 3 a - 3   d  causes the loop to slide through the slot and off the attachment assembly. 
     The minimum width “s” of the slot  16  is constrained by the width of the material used to construct the lanyard  20 . When the slot angle  18  is large, unwanted detachment can be avoided by increasing the friction between the preformed loop  22  and the attachment assembly. Increasing the friction has the effect of requiring a greater force be used to detach the preformed loop  22  and reduces the likelihood of use of the dust cover  10  resulting in detachment of the preformed loop from the attachment assembly. In alternative embodiments of the dust cover constructed from the same materials and with the same dimensions as the embodiment described above, acceptable performance was achieved for slot angles  18  in the range of 30° to 60°. 
     Other factors that influence the ease with which the attachment assembly enables the preformed loop  22  of a lanyard  20  to be attached to or detached from the dust cover  10  include the hub diameter “d” of the groove  14  and the internal diameter of the preformed loop  22 . Increasing the hub diameter “d” of groove  14  has the effect of requiring more force to attach and detach the preformed loop  22  using the attachment assembly of the dust cover. Conversely, increasing the internal diameter of the preformed loop  22  has the effect of requiring less force to attach and detach the preformed loop  22  of the lanyard  20  using the attachment assembly. 
     In an alternative embodiment of the dust cover in accordance with practice of the present invention, the plastic lanyard  20 ′ of FIG. 2 b  is attached to the dust cover using the attachment assembly. The material used to construct the plastic lanyard  22  is chosen such that it has a flexural modulus large enough to enable the preformed loop  22  to be deformed to lift out of the slot  16  during attachment, but small enough to prevent the preformed loop  22  from detaching from the dust cover  10  without proceeding through the slot  16  of the attachment assembly. For the preferred embodiment of the dust cover  10  described above, a lanyard  20 ′ with a circular preformed loop  22 ′ constructed from a material having a flexural modulus in the range of 330-420 kilo pounds per square inch (“kpsi”) can be used, such as an injection molded lanyard constructed from engineering grade nylon 6/6, which has a flexural modulus of 380 kpsi. 
     Plastics with a flexural modulus lower than 330 kpsi can be used. However, a plastic lanyard constructed from a material with a flexural modulus lower than 330 kpsi and a circular preformed loop  22  cannot be used in combination with the dust cover  10  described above because the preformed loop could not be deformed to lift out of the slot  16  during attachment. A plastic lanyard constructed from a material with a flexural modulus lower than 330 kpsi and constructed to have a non-circular shape similar to the shape of the preformed loop of the flexible lanyard shown as  22  in FIG. 2A can be used in combination with the dust cover  10  described above, because the irregular shape enables the preformed loop to lift out of the slot during attachment. 
     Although the embodiments recited above relate to the attachment of a preformed loop to a dust cover, the methods and techniques described above are equally adaptable to the attachment of a preformed loop to any structure having a groove and a flange with a slot in it. In other embodiments, the attachment assembly can be used to attach preformed loops to a wide variety of objects including covers for containers, computers, luggage, merchandise, clothing, shoes, buildings, seagoing vessels or any other object that requires the attachment of a lanyard. 
     While the above description contains many specific features of the invention, these should not be construed as limitations on the scope of the invention, but rather as an example of one preferred embodiment thereof. Many other variations are possible. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

Technology Category: f