WO2000069294A1

WO2000069294A1 - Fiber optic cable coupling system

Info

Publication number: WO2000069294A1
Application number: PCT/US2000/013741
Authority: WO
Inventors: Jack Caruso
Original assignee: Optic-Tech International Corp.
Priority date: 1999-05-19
Filing date: 2000-05-19
Publication date: 2000-11-23
Also published as: WO2000069294A8; AU5029300A

Abstract

A fiber optic cable coupling system comprising a mounting member (6) and a fiber optic plug assembly. The mounting member (6) is attached to an opening in the housing (2) of a light source and has a hollow cylindrical cavity. A retaining pin (5) extends from an exterior surface of the mounting member to the cavity. The fiber optic plug assembly is connected to one or more ends of the fiber optic cables (9) and includes an exterior surface adapted to slidably enter the mounting member cavity. The fiber optic plug further includes an annular retaining groove (41) on the exterior surface and a hollow cylindrical cavity through which the fiber optic strands travel. When the fiber optic plug assembly fully extends into the mounting member, the retaining pin (5) engages the retaining groove (41). As a result of the structure, the fiber optic strands may rotate as needed but the fiber optic plug assembly will not release from or move in the mounting member (6).

Description

FIBER OPTIC CABLE COUPLING SYSTEM

This application is a continuation-in-part of U.S. application serial-number of 09/314,068 filed May 19, 1999.

BACKGROUND OF THE INVENTION

Field Of The Invention

The present invention relates to a coupling system for connecting one or more fiber optic cables to a light source. More particularly, the invention provides assemblies that provide superior coupling of the fiber optic cables to the light source.

Description Qf The Background Art

An optical fiber is an elongated glass or plastic filament having a core region surrounded by one or more layers of cladding, with the core having a higher index of refraction than the cladding so that light introduced at one end of the fiber will be internally reflected for transmission longitudinally within the core channel to the other end of the fiber. A fiber optic cable comprises a sheath surrounding a multiplicity of optical fibers. The size of the fiber optic cables may vary widely depending on the number and size of the optical fibers within the sheath. Typically, one end of the fiber optic cable is coupled to a light source to receive light energy, and the other end is positioned to emit the received light anergy at an area to be illuminated. Because the fiber optic cables are often used to illuminate outdoor areas that are exposed to the elements, the light source is usually enclosed within a housing to form a lamp box. The housing generally includes some type of coupling structure to connect with the fiber optic cables and to provide the fiber optic cables access to the light source. Coupling of the fiber optic cable to the lamp box is conventionally accomplished using ferrules having multiple screws, dowels, and brackets to tightly mount the cable. This type of connection makes installation of the fiber optic cables to the lamp box awkward, tedious and time-consuming.

One system to couple the fiber optic cables to the light source is illustrated in FIG. 1. In this system, a fiber optic plug is installed on an end of the fiber optic cables. The fiber optic plug includes a locking slot 1. At the leading end of the locking slot 1 is a flange 11 having a generally elliptical shape with flat top and bottom surfaces 111 and 112. An opening adapted to mate with the flange 11 is provided in the housing 2 of the lamp box. To connect the fiber optic cables to the lamp box, the fiber optic plug is inserted into the opening and rotated 90°. As a result of the rotation, the housing 2 engages the flange 11 and the locking slot 1.

However, the coupling system suffers from several disadvantages. Rotation of the fiber optic plug may cause an inadvertent detachment of the fiber optic cable from the housing 2 of the lamp box. Similarly, the rotation of the fiber optic plug may interfere with the engagement of the housing 2 with the flange 11 and the locking slot 1. Although still coupled to the housing 2, the fiber optic plug may move slightly withing the opening in the housing 2 of the lamp box. Because of this motion, the optical fibers may not stay in an ideal position to receive light from the lamp. In particular, the end of the optical fibers should be perpendicular to the path of the light energy to maximize absorption of light energy into the optical fibers. Motion in the fiber optic plug may misalign the optical fibers, preventing some of the desirable illumination from the light source to not enter the optical fibers. Even a slight motion in the fiber optic plug may drastically reduce light absorption. Furthermore, the fiber optic plug must mate almost perfectly to the opening in the housing 2 in order to achieve a sturdy connection. For instance, the width of the locking slot 1 should be substantially similar to the width of the housing 2. Otherwise, the fiber optic plug can move within the opening in the housing 2. Even if the sizes of elements of the coupling system initially match, contacting surfaces may wear during use and alter the dimensions of fiber optic plug and the opening in the housing. Thus, this coupling system almost inevitably allows the undesirable motions in the fiber optic plug.

Therefore, the goal of the present invention is to provide an improved coupling system for connecting one or more fiber optic cables to the housing of a lamp box.

SUMMARY OF THE INVENTION In order to meet this and other goals, the present invention provides an improved coupling system for connecting a fiber optic cable to a lamp box. In particular, the present invention provides a fiber optic coupling system that optically connects at least one fiber optic cable containing a plurality of fiber optic strands to a lamp box. The fiber optic coupling system includes a mounting member adapted to be secured to an exterior surface of a lamp box. This mounting member has a hollow cylindrical mounting member sleeve having a distal end capable of extending through the wall of the lamp box into the interior of the lamp box. The mounting member further includes a mounting collar that is circumferentially disposed around a proximal end of the mounting sleeve. The mounting member also includes a locking pin that passes from an exterior surface of the mounting plate into an internal cavity.

The present coupling system further includes a fiber optic plug assembly adapted to mate with the mounting member to thereby couple the fiber optic cable to the lamp box. The fiber optic plug assembly includes a hollow, cylindrical fiber optic plug sleeve having an interior cavity that receives fiber optic strands from the fiber optic cables. The fiber optic plug sleeve further includes an exterior surface sized and shaped to slidably engage the interior cavity of the mounting member sleeve. Also, the exterior surface of the fiber optic plug sleeve has an annular retaining groove that receives the locking pin when the fiber optic plug assembly is fully inserted into the mounting member. With this system, the fiber optic plug assembly can rotate but does not separate from, or move axially within, the mounting member.

At a proximal end, the fiber optical plug assembly may further include a fiber optic seal. The fiber optic seal helps prevents external contaminants from entering fiber optic plug assembly. The fiber optic plug assembly may also include a double-ended connecter that attaches to the fiber optic plug sleeve and the fiber optic seal.

In a preferred embodiment, the fiber optic plug assembly further includes a hollow cylindrical fiber optic reducer sleeve. The fiber optic reducer sleeve has an exterior wall sized and shaped to slidably enter and engage the cavity of the fiber optic plug sleeve and an interior cavity having a diameter selected to securely accommodate a preselected quantity of fiber optic strands. The fiber optic coupling system can be adapted to accommodate various sized bundles of fiber optic strands by providing fiber optic reducer sleeves having a variety of inner diameters. The fiber optic reducing sleeve may further include indicia to specify the diameter of the internal cavity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a coupling system known in the prior art; and FIGS. 2 through 5 are schematic views of a fiber optic coupling system in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION With reference to the figures, exemplary embodiments of the invention will now be described. The embodiments illustrate principles of the invention and should not be construed as limiting the scope of the invention.

As illustrated in FIGS. 2-5, the present invention offers a system to connect fiber optic strands 9 to the housing 2 of a lamp box. In particular, the present invention comprises a fiber optic plug assembly that circumferentially surrounds the fiber optic strands 9 at one or both ends of the fiber optic cable, and a mounting member β that mounts to the housing 2 of the lamp box and is adapted to mate with the plug assembly. The fiber optic plug assembly of the present invention comprises a fiber optic reducer sleeve 3, a fiber optic plug sleeve 4, and a fiber optic seal assembly 8. These elements will now be described in greater detail. The fiber optic plug sleeve 4 is of a hollow, generally cylindrical structure with a plug sleeve cavity 42 and an exterior step 43 at a proximal end. A radial retaining groove 41 is provided on an exterior surface of the fiber optic plug sleeve 4, and the role of the retaining groove 41 is discussed subsequently. The plug sleeve cavity 42 has an outward taper 44 at a proximal end and a cylindrical portion with a diameter (d) sized to accept a preselected number of fiber optic strands 9. For example, the internal diameter of the fiber optic plug sleeve 4 can vary from about 0.25 inch to about 1.0 inch, and can be supplied in increments of 0.25 inch to accommodate a wide variety of fiber optic cables. Other connection devices could only accept, at most, optical cables bundles having 500 fibers with a diameter of 0.75 mm or 432 fibers with a diameter of 1mm. Accordingly, the present invention reliably connects larger bundles of optical fibers to allow greater light transfer from the same lamp box.

For different sized bundles of optic strands 9, the present invention provides a series of optional fiber optic reducer sleeves 3 that are adapted to mate with the fiber optic plug sleeve 4. The fiber optic reducer sleeve 3 is a hollow structure with an inner cavity 33, a generally cylindrical portion 32 at a distal end, and an external sleeve step 31 at a proximal end. The generally cylindrical portion 32 has an outer diameter in the order of (d) to fit relatively snugly within the plug sleeve cavity 42. The external sleeve step 31 similarly mates to the outward taper 44. The fiber optic reducer sleeve 3 has an inner diameter (d' ) that is appropriately sized to accept a preselected bundle of fiber optic strands 9. Accordingly, the inner diameter (d' ) of the fiber optic reducer sleeve 3 varies according to the size and number of the fiber optic strands 9. The fiber optic reducer sleeve 3 may be further adapted to engage the fiber optic plug sleeve 4. For example, the exterior surface of the fiber optic reducer sleeve 3 may contain threads that engage an internal portion of the fiber optic plug sleeve 4.

The fiber optic reducer sleeve 3 may also contain indicia 34, which indicate to the user the inner diameter (d' ) of the inner reducer sleeve cavity 33. The indicia 34 may include alphanumeric symbols, colored strips, or other types of coding to enable the user the select the appropriately sized reducer sleeve 4 based upon the size of the fiber optic bundle.

The fiber optic seal assembly 8 includes two elements, a double-ended connector 81 and a cap 82. The cap 82 has an annular opening at a proximal end to accept the fiber optic cable. The proximal opening may be sized to form a tight connection around the fiber optic cable to prevent entry of contaminants into the fiber optic plug assembly. The double-ended plug connector 81 has an internal cavity to accept the fiber optic strands 9. Furthermore, the double-ended plug connector 81 has a proximal end adapted to engage the distal end of the cap 82. The double- ended connector 81 and the cap 82 may form a male-to-female connection where an external surface of the double-ended plug connector 81 engages an internal surface of the cap 82. For example, the double-ended connector 81 and the cap 82 may each be threaded so that the two elements become engaged with an application of a twisting force.

The cap 82 may have an internal seal step 83 at a distal end, and the double-ended plug connector 81 may be tapered at a distal end to match this step 83.

Preferably, the fiber optic seal assembly 8 also includes a seal washer 84 positioned between the cap 82 and the double-ended plug connector 81. The engagement of the double-ended connector 81 and the cap 82 causes the seal washer 84 to compress to helps prevent contaminants such as rain water from flowing into the fiber optic plug assembly. The double-ended plug connector 81 is further adapted at a distal end to engage the proximal end of the fiber optic plug sleeve 4. For example, the double-ended plug connector 81 and the fiber optic plug sleeve may similarly form a male-to female connection where an external surface of the double-ended plug connector 81 engages an internal surface of the fiber optic plug sleeve 4. The mounting member 6 is a mounted in an opening in the housing 2 of the lamp box. The mounting member has a collar 63 that remains outside the lamp box and a mounting member sleeve 65 that extends into the lamp box. The mounting member 6 may be fastened to the housing 2 by tightening a binding bolt 62. Alternatively, the mounting member 6 may be glued or welded to the housing 2. The mounting member 6 is a generally cylindrical structure with an interior cavity 64 that is adapted to accept the distal end of the fiber optic positioning sleeve 4. For example, the diameter of mounting member cavity 64 should be in the order of the outside diameter of the distal end of the fiber optic positioning sleeve 4. The mounting member 6 has a retaining hole 61 that corresponds with the retaining groove 41 when the fiber optic plug sleeve 4 is fully inserted. When the fiber optic plug sleeve 4 is fully inserted, the plug sleeve step 43 contacts the mounting member collar 63. The mounting member 6 fastens the fiber optic plug sleeve 4 by using a retaining pin 5 in the position hole 61. In particular, the retaining pin 5 engages the retaining groove 41 when the fiber optic plug is fully inserted into the mounting member 6. The locking pin may include a spring 7 to apply a continuous force to the engagement with the retaining groove 41. In addition, the retaining pin 5 may include a handle to allow manipulation by users. The retaining pin 5 may further include means to engage the mounting member 6. For example, the retaining pin 5 may be threaded to engage a section of the position hole 61.

The operation of the present invention will now be summarized. To prepare the fiber optic plug assembly, the covering (jacketing) material is removed from the end of the fiber optic cable (s). The uncovered fiber optic strands are wrapped with tape to prevent fraying and inserted into the proximal end of the cap 82 and through the central cavity of the double-ended plug connector 81. The double-ended plug connector 81 then engages the distal end of the cap 82 to secure the optical cable (s) within the plug assembly. At this point, the optical fibers may be passed through the inner cavity of the fiber optic positioning sleeve 4. If the size of the bundle the fiber optic strands 9 is smaller than the inner diameter of the fiber optic positioning sleeve 4, a fiber optic reducer sleeve 3 of appropriate inner diameter is used to reduce the diameter of the passageway for the fiber optic strands 9. The fiber optic positioning sleeve 4 then engages the distal end of the double-ended plug connector 81 to complete the fiber optic plug assembly. Any excess in the fiber optic strands 9 are now trimmed away with a cutting tool, such as a hot blade.

The fiber optic positioning sleeve 4 and the end of the fiber optic strands 9 are then inserted through the inner cavity of the mounting member 6. As a result, the fiber optic positioning sleeve 4 and the ends of the fiber optic strands 9 pass through the housing 2 to enter the interior of the lamp box. When the fiber optic plug sleeve 4 is inserted into the housing 2, the mounting member collar 63 has an edge contacting the plug sleeve step 43 of the fiber optic plug sleeve 4. Also, the exterior surface of fiber optic plug sleeve 4 contacts the interior surface that defines the mounting member cavity 64.

By engaging the retaining pin 5 into the retaining groove 41, the fiber optic plug assembly locks into the housing 6 of the lamp box, no matter how the fiber optic strands 9 and the fiber optic plug assembly rotate. Thus, the present invention provides a system for connecting fiber optic cables to a lamp box where the cables may radially twist as needed, but the optical fibers are kept perpendicular to the light source to maximize light absorption. Since many modifications, variation, and changes in detail may be made to the described emboαiments, it is intended that all the matter in the foregoing αescriptions and shown m the accompanying drawings be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1. A fiber optic coupling system for optically connecting at least one fiber optic cable that is comprised of a plurality of fiber optic strands to a lamp box, comprising: (a) a mounting member adapted to be secured to an exterior surface of the lamp box and comprising (i) a hollow cylindrical mounting member sleeve having a distal end capable of extending into the interior of the lamp box and (ii) a mounting plate circumferentially disposed around said mounting sleeve at a proximal end thereof, with a locking pin passing through an exterior surface of the mounting plate and extending into an internal cavity of said mounting plate; and

(b) a fiber optic plug assembly adapted to mate with said mounting member, comprising a hollow cylindrical fiber optic plug sleeve having an interior cavity receiving fiber optic strands from said at least one fiber optic cable and having an exterior surface dimensioned to slidably engage said mounting member sleeve, said fiber optic plug sleeve having an annular retaining groove in the exterior surface thereof, wherein said locking pin engages said annular retaining groove when said fiber optic plug assembly is fully inserted into said mounting member.

2. The fiber optic coupling system of claim 1, wherein said fiber optic plug assembly further comprises a hollow cylindrical fiber optic reducer sleeve having an exterior wall dimensioned to slidably engage with the inner surface of the interior cavity of said fiber optic plug sleeve and an interior cavity having a diameter selected to securely accommodate a preselected quantity of fiber optic strands.

3. The fiber optic coupling system of claim 2, wherein said fiber optic reducer sleeve comprises indicia of said interior diameter.

4. The fiber optic coupling system of claim 1, wherein said fiber optic plug assembly further comprises: a hollow cylindrical double-ended plug connector having a distal end adapted to engage the fiber optic plug sleeve, a proximal end, and an interior cavity to accommodate the fiber optic strands; and a hollow cylindrical cap having an annular opening in the proximal end adapted to secure the fiber optic cable and a distal end adapted to engage the double-ended plug connector.

5. The fiber optic connecting system of claim 1, wherein said fiber optic plug sleeve extends into an interior space of the lamp box, beyond said mounting member sleeve and the fiber optic strands.

6. A method for optically connecting at least one fiber optic cable that is comprised of a plurality of fiber optic strands to a lamp box, comprising:

(a) connecting a mounting member to an exterior surface of the lamp box wherein the mounting member comprises (i) a hollow cylindrical mounting member sleeve having a distal end capable of extending into the interior of the lamp box and (ii) a mounting plate circumferentially disposed around said mounting sleeve at a proximal end thereof, with a locking pin passing through an exterior surface of the mounting plate and extending into an internal cavity of said mounting plate;

(b) installing a fiber optic plug assembly on one or more ends of the fiber optic strands, wherein the fiber optic plug assembly

(i) is adapted to mate with said mounting member, and

(ii) comprises a hollow cylindrical fiber optic plug sleeve having an interior cavity receiving fiber optic strands from said at least one fiber optic cable and having an exterior surface dimensioned to slidably engage said mounting member sleeve, said fiber optic plug sleeve having an annular retaining groove in the exterior surface thereof, wherein said locking pin engages said annular retaining groove when said fiber optic plug assembly is fully inserted into said mounting member; and

(c) inserting the fiber optic plug assembly into the said mounting member.