Optical fiber junction box and method of positioning an optical cable therein

Abstract: An optical fiber junction box includes a wall (31) having an entry slot (32) at least partially defined by spaced apart edges; and a conduit (42) for enclosing an optical fiber having a plurality of radial grooves (43), wherein an outer diameter of at least one of the radial grooves is approximately equal to a distance between the spaced apart edges such that the conduit is secured to the junction box when the spaced apart edges of the entry slot are positioned in one of the radial grooves of the conduit.

Description: The invention relates generally to an optical fiber junction box and a method for positioning the optical fibers relative to a junction box. DE-A-4218378 discloses a smooth surface conduit which is inserted through an aperture in a grommet which has a recessed groove formed around an outside edge thereof in order to be fitted into a hole in a junction box. The grommet maintains the assembly in a correct position. The abstract of JP-A-7063284 discloses an assembly of the same type. A smooth surface conduit is inserted through an aperture in a grommet fitted into a hole in a junction box. The object underlying the invention is to provide an improved junction box suitable for optical fibers and a method of positioning optical fibers relative to a junction box which effect simple, efficient and secure placement of the optical fibers relative to the junction box while preventing damage to the optical fibers. In accordance with the invention, this object is accomplished by the features of claim 1 and 6. Brief Description of the Drawings Fig. 1 is a perspective view of a optical fiber junction box embodying the concept of the present invention; Fig. 2 is a fragmentary perspective view of the connection between the corrugated conduit and the junction box wall of Fig. 1; Fig. 3 is a fragmentary top view of the junction box of Fig. 1, with the cover removed; Fig. 4 is a fragmentary sectional view of the box of Fig. 1 taken along line 4-4 of Fig. 3; Fig. 5 is a fragmentary sectional view taken along line 5-5 of Fig. 4; Fig. 6 is a sectional view taken along line 6-6 of Fig. 5; Fig. 7 is a fragmentary sectional view taken along line 7-7 of Fig. 4; Fig. 8 is a fragmentary view showing a cable tie secured within a cable tie receiving slot for securing the conduit to the box; Fig. 9 is fragmentary sectional view of an alternative embodiment of a conduit securing structure formed in a wall of the box of Fig. 1; and Fig. 10 is a fragmentary sectional view of the conduit securing structure of Fig. 9, taken along line 10-10 of Fig. 9. Description of the Preferred Embodiment A optical fiber junction box embodying the concept of the present invention is designated by the numeral 20 in the accompanying drawings. Box 20 includes a base 21 and a removable lid 22. Base 21 includes integral flanges 23 for attachment of base 21 to vertical patch panel support members 24. A latch 25 secures lid 22 to base 21. As seen in Fig. 3, the inner surface of box base 21 includes removable clips 26 and spools 27 for positioning and arranging fiber optic cables 28 and individual optic fibers 29 within the box 20. Base 21 is preferably formed of metal and includes a vertical back wall 30 and vertical side walls 31. Provided in back and side walls 30 and 31 are a plurality of entry slots 32. As seen in Fig. 6, entry slots 32 include a radiused inner edge 33 and vertical edges 34. As seen in Figs. 1-8, disposed below each entry slot 32 is a cable tie receiving slot 35. Disposed adjacent each entry slot 32 are a pair of holes 36, see Fig. 6, for accepting fasteners 37, see Fig. 2, to secure a cable tie positioning fixture 38 adjacent each entry slot 32. As seen in Fig. 4, cable tie positioning fixture 38 is formed of plastic and includes a flange 39 for positioning and securing a strap 40 of a self locking cable tie 41 to box base 21. Corrugated fiber optic conduit 42 is a standard product utilized in the art to contain and protect fiber optic cables 28 or fibers 29 by enclosing the same while preventing movement of enclosed cables or fibers beyond their minimum bend radius which would damage the optic fibers. Conduit 42 includes a plurality of axially spaced indented radial grooves 43 that allow the desired amount of flexing of the conduit but resist undesired excessive bending of the conduit. To facilitate the ease of connection of conduit 42 to tray 20, to provide a more secure joint between conduit 42 and box 20 and to prevent damage to the optical fibers contained therein the present invention positions edges 34 of entry slots 32 within a radial groove 43 of conduit 42 which prevents axial movement of conduit 42 relative to box base 21. Vertical edges 34 of each entry slot 32 are spaced apart a distance slightly greater than or approximately equal to the outer diameter of the conduit in radial groove 43 such that conduit 42 is securely held within entry slot 32 after conduit 42 is inserted between vertical edges 34. See Figs. 6 and 7. The resiliency of conduit 42 allows some interference with edges 34 without damaging conduit 42. Conduit 42 is then preferably securely fastened to box base 21 with a cable tie 41 which fastens conduit 42 to cable tie positioning fixture 38. See Fig. 2. An alternative way of fastening conduit 42 to base 21 of tray 20 is shown in Fig. 8, where cable tie 41 is passed through cable tie receiving slot 35 in vertical walls 30 or 31 and secured around conduit 42. Another means for fastening conduit 42 securely to base 21 is shown in Figs. 9 and 10, where a plurality of tabs 44 are formed out of a portion of a vertical wall of base 21, adjacent each entry slot 32. Tabs 44 project inwardly parallel to a planar surface 45 of base 21 to present a surface for receipt of strap 40 of a cable tie 41 for fastening conduit 42 to base 21. A distal edge 46 of each tab 44 is bent downwardly toward surface 45 to retain cable tie 41 relative to tab 44. The method of the present invention is practiced by providing a junction box base 21 having an entry slot 32 in a wall 30 of base 21 and providing a fiber optic conduit 42 having a radial groove 43 sized to fit snugly within the slot and positioning the spaced apart edges 34 of entry slot 32 in one of radial grooves 43 of the conduit 42 to securely engage conduit 42 with wall 30 or 31 of base 21. An additional step of securing conduit 42 to base 21 with cable tie fastener 41 prevents inadvertent disengagement of conduit 42 from base 21 and provides strain relief thereto.

Claims: An optical fiber junction box, comprising: a wall (30, 31) having an entry slot (32) at least partially defined by spaced apart edges (34) in a wall of the box; and a cylindrical conduit (42), for enclosing an optical fiber (28,29) and, having a plurality of radial grooves (43) wherein an outer diameter of the radial grooves (43) is approximately equal to the distance between the spaced apart edges (34) such that the conduit is secured to the junction box when one of the radial grooves (43) of the conduit is positioned within the spaced apart edges of the entry slot. An optical fiber junction box as set forth in claim 1, including fastening means disposed adjacent the entry slot for securing a fastener around the conduit to secure the conduit to the optical fiber junction box. An optical fiber junction box as set forth in claim 2, wherein the fastening means includes an elongate self locking fastener (41) and a plastic bracket (38) fastened to the box. An optical fiber junction box as set forth in claim 2, wherein the fastening means includes an elongate self locking fastener (41) and a cable tie receiving slot (35) formed in the wall of the box. An optical fiber junction box as set forth in claim 2, wherein the fastening means includes an elongate self locking fastener (41) and a tab (44) formed out of the surface of the wall of the box. A method of positioning optical fibers relative to a junction box, comprising the steps of: Providing an entry slot (32) at least partially defined by spaced apart edges (34) in a wall of the box; Providing a cylindrical conduit (42) for enclosing an optical fiber, and having a plurality of radial grooves (43) sized to fit snugly within the slot; and positioning one of the radial grooves (42) of the conduit between the spaced apart edges (34) of the entry slot to securely engage the conduit with the wall of the box. A method as set forth in claim 6, including the step of securing the conduit to the box with an elongate fastener.

Inventors: CAVENEY JACK E, CAVENEY, JACK E.
Applicants: PANDUIT CORP, PANDUIT CORPORATION
Application year: 1997
Main classification: G02B6
IPC codes: G02B6, H02G3