Fiber optic cable having spliceless fiber branch and method of making

• US 5,125,060 A
• Filed: 04/05/1991
• Issued: 06/23/1992
• Est. Priority Date: 04/05/1991
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Edmundson, Gary W.
• Primary Examiner(s): Ullah, Akm E.
• Application Number:
  US07/680,991
• Time in Patent Office: 445 Days
• Field of Search: 385/100-104
• US Class Current: 385/100
• CPC Class Codes: G02B 6/2804 forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
• CPC Class Codes: G02B 6/4472 Manifolds
• CPC Class Codes: G02B 6/4473 Three-way systems
• CPC Class Codes: G02B 6/4476 with heat-shrinkable elements

Abstract

A spliceless optical fiber cable has a main distribution cable having a plurality of optical fibers disposed therein and at least one stub or drop cable extending from the distribution cable at one or more branch points. The stub or drop cables are configured with the distribution cable in a manner such that no splices are required. At each branch point, an optical fiber branch module is utilized for protecting the optical fibers from moisture and mechanical damage, providing a strong anchoring point for the stub or drop cable, and insuring that the minimum bend radius is not violated. The spliceless optical fiber cable is made by accessing the specified optical fibers at a disconnect point along the length of the distribution cable and cutting the specified optical fibers. At the branch point, the specified optical fibers are again accessed and carefully pulled from within the buffer tube and protective elements of the distribution cable so that a length of the specified optical fibers is disposed outside of the distribution cable.

Claims

1. A fiber optic cable assembly, comprising:

a distribution cable having a predetermined length and having first and second ends, said distribution cable further having a branch point being positioned along the length thereof, said distribution cable including;

optical fiber buffering means having a length substantially equal to said predetermined length and having first and second ends, at least one optical fiber of substantially said predetermined length disposed within and enclosed by said buffering means, said fiber having first and second ends substantially coincident with the first and second ends of said distribution cable, and at least one branching optical fiber having first and second ends and having a first portion extending between its first end being coincident with said distribution cable first end and said branch point, said first portion being disposed within and enclosed by said buffering means and having a second portion extending between said branch point and its second end, said second portion being disposed outside of said buffering means and being continuous with said first portion; and

at least one branch cable having buffering means for encompassing said second portion of said branching optical fiber.

2. A fiber optic cable assembly as described in claim 1, wherein said fiber optic cable assembly further comprises means secured to said distribution cable and to said branch cable for encompassing said branch point.

3. A fiber optic cable assembly as described in claim 2, wherein said branch point encompassing means includes a branch module having a branch module body having means for receiving a length of said distribution cable extending therethrough and means for receiving said branch cable.

4. A fiber optic cable assembly as described in claim 3, wherein said branch module further has means for securing a strength member of said branch cable to said branch module body.

5. A fiber optic cable assembly as described in claim 3, wherein said branch module further has means for securing a strength member of said distribution cable to said branch module body.

6. A fiber optic cable assembly as described in claim 3, wherein said branch point encompassing means further includes conductive means for connecting an armored jacket of said distribution cable to said branch module body and for connecting an armored jacket of said branch cable to said branch module body.

7. A fiber optic cable assembly as described in claim 3, wherein said branch module has first and second ends, said distribution cable receiving means being disposed at said branch module first and second ends, whereby said length of distribution cable extends between said branch module first and second ends.

8. A fiber optic cable assembly as described in claim 7, wherein said branch module has a maximum outer diameter of less than 1.25 inches.

9. A fiber optic cable assembly as described in claim 7, wherein said branch module length is less than five inches.

10. A fiber optic cable assembly as described in claim 3, wherein said branch point encompassing means further includes means for covering said branch module.

13. A fiber optic cable assembly as described in claim 1, wherein said second portion of said branching optical fiber has a specified length no greater than 12 feet.

14. A fiber optic cable assembly as described in claim 13, wherein said distribution cable further includes a disconnect point positioned along the length of said distribution cable, said disconnect point being positioned at said specified length no greater than 12 feet from said branch point.

15. A fiber optic cable assembly as described in claim 14, wherein said disconnect point is encompassed by heat-recoverable wrap.

16. A fiber optic cable assembly as described in claim 1, wherein said second portion of said branching optical fiber has a specified length greater than 12 feet and further wherein said distribution cable further includes a disconnect point is positioned said specified length greater than 12 feet away from said branch point along the length of said distribution cable.

17. A fiber optic cable assembly as described in claim 16, wherein said distribution cable further includes at least one access point positioned between said branch point and said disconnect point along the length of said distribution cable.

18. A fiber optic cable assembly as described in claim 2, wherein said distribution cable buffering means includes a monotube encompassing said optical fibers and further wherein said distribution cable further includes at least one strength member extending longitudinally with said monotube.

19. A fiber optic cable assembly as described in claim 18, wherein said branch point encompassing means includes means for securing said at least one strength member to said branch point encompassing means.

20. A fiber optic cable assembly as described in claim 2, wherein said branch cable buffering means includes a monotube encompassing said second portion of said branching optical fiber and further wherein said branch cable further has at least one strength member extending longitudinally with said branch cable monotube.

21. A fiber optic cable assembly as described in claim 20, wherein said branch point encompassing means further includes means for securing said at least one strength member of said branch cable to said branch point encompassing means.

11. A fiber optic cable assembly as described in claim 11, wherein said covering means comprises a heat-recoverable wrap.

12. A fiber optic cable assembly as described in claim 11, wherein said covering means further comprises a non-adhesive wrap disposed between said branch module and said heat-recoverable wrap.

22. A method of making a fiber optic cable assembly utilizing a distribution cable having a predetermined length and having first and second ends, said distribution cable further having a branch point and a disconnect point each being positioned along the length of said distribution cable, said distribution cable including;

optical fiber buffering means of said predetermined length, at least one optical fiber of said predetermined length disposed within and enclosed by said buffering means, said optical fiber having first and second ends coincident with said first and second ends of said distribution cable, and at least one branching optical fiber having first and second ends and having a first portion extending between the branching optical fiber first end being coincident with said distribution cable first end and said branch point and having a second portion extending between said branch point and the branching optical fiber second end being coincident with said disconnect point, said branching optical fiber being disposed within and enclosed by said distribution cable buffering means, and at least one branch cable having buffering means, said method comprising the steps of;

removing a portion of said distribution cable buffering means at said branch point so that said branching optical fiber is accessible;

removing said branching optical fiber second portion from within said distribution cable buffering means so that said branching optical fiber second portion is disposed outside of said distribution cable buffering means; and

configuring said branch cable buffering means so that it encompasses said branching optical fiber second portion.

23. A method of making a fiber optic cable assembly as described in claim 22, wherein said method further comprises the step of enclosing said branch point with a branch module.

24. A method of making a fiber optic cable assembly as described in claim 23, wherein said method further comprises the step of encapsulating said branch module with a heat-recoverable wrap.

25. A method of making a fiber optic cable assembly as described in claim 23, wherein said method further comprises the steps of encapsulating the branch module with a non-adhesive wrap and encapsulating said non-adhesive wrap with a heat-recoverable wrap.

26. A method of making a fiber optic cable assembly as described in claim 22, wherein said fiber optic cable assembly includes a plurality of branch cables and said method further comprises the step of strapping said plurality of branch cables to said distribution cable.

27. A method of making a fiber optic cable assembly as described in claim 23, wherein said distribution cable buffering means includes at least one buffer tube and said distribution cable further includes an outer jacket encapsulating said buffer tube and further wherein said method further comprises, before said distribution cable buffering means removing step, the step of removing the portion of said outer jacket at said branch point.

28. A method of making a fiber optic cable assembly as described in claim 27, wherein said distribution cable further comprises an armored jacket disposed between said outer jacket and said buffer tube and further wherein said method further comprises, after said outer jacket removing step, the step of removing the portion of said armored jacket at said branch point.

29. A method of making a fiber optic cable assembly as described in claim 28, wherein said distribution cable further includes an inner jacket disposed between said armored jacket and said buffer tube and further wherein said method further comprises, after said armored jacket removing step, the step of removing said inner jacket at said branch point.

30. A method of making a fiber optic cable assembly as described in claim 29, wherein said distribution cable further includes radial strength yarns disposed between said inner jacket and said buffer tube and further wherein said method further comprises, after said inner jacket removing step, the step of removing said radial strength yarns at said branch point.

31. A method of making a fiber optic cable assembly as described in claim 28, wherein said method further comprises the step of connecting a grounding strap between said armored jacket and said branch module.

32. A method of making a fiber optic cable assembly as described in claim 23, wherein said branch cable further comprises at least one strength member and said method further comprises the step of securing said at least one strength member to said branch module.

33. A method of making a fiber optic cable assembly utilizing a distribution cable having a predetermined length and having first and second ends, said distribution cable further having a branch point and a disconnect point each being positioned along the length of said distribution cable, said distribution cable including;

optical fiber buffering means of said predetermined length, a plurality of optical fibers of said predetermined length disposed within and enclosed by buffering means, said optical fibers having first and second ends coincident with the first and second ends of said distribution cable, and at least one branch cable having buffering means, said method comprising the steps of;

removing a portion of said distribution cable buffering means at said disconnect point so that said plurality of optical fibers are accessible;

cutting at least one of said plurality of optical fibers at said disconnect point;

removing a portion of said distribution cable buffering means at said branch point so that said at least one optical fiber is accessible;

moving from within said distribution cable buffering means the length of said at least one optical fiber extending between said branch point and said disconnect point so that said length of said at least one optical fiber is disposed outside of said distribution cable buffering means; and

configuring said branch cable buffering means so that it encompasses said length of said at least one optical fiber.

34. A method for making a fiber optic cable assembly as described in claim 33, wherein said fiber optic cable assembly further has a branch module and said method further comprises the step of enclosing said branch point with said branch module.

35. A method of making a fiber optic cable assembly as described in claim 34, wherein said method further comprises the step of encapsulating said branch module with a heat-recoverable wrap.

36. A method of making a fiber optic cable assembly as described in claim 33, wherein said method further comprises the step of encapsulating said disconnect point with heat-recoverable patch.

37. A method of making fiber optic cable assembly as described in claim 33, wherein said branch cable buffering means configuring step comprises inserting an end of said length of said at least one optical fiber into an end of said branch cable buffering means and moving said length of said at least one optical fiber into said branch cable buffering means until said length of said at least one optical fiber is substantially completely encompassed by said branch cable buffering means.

38. A method of making a fiber optic cable assembly as described in claim 33, wherein said at least one branch cable further has a string having a length greater than the length of said branch cable buffering means, said string being encompassed by said branch cable buffering means, and further wherein said branch cable buffering means configuring step comprises attaching one end of said string to an end of said length of said at least one optical fiber and pulling said string at its other end so that said branch cable buffering means substantially completely encompasses said length of said at least one optical fiber and said string is disposed outside of said branch cable buffering means.

39. A method of making a fiber optic cable assembly as described in claim 33, wherein said disconnect point is positioned at a specified length greater than 12 feet from said branch point along the length of said distribution cable, said distribution cable further having at least one access point positioned between said branch point and said disconnect point, said method further comprises, before said moving step, the steps of removing a portion of said distribution cable buffering means at said access point so that said at least one optical fiber is accessible, and moving from within said distribution cable buffering means the length of said at least one optical fiber extending between said access point and said disconnect point so that said length of said at least one optical fiber is disposed outside of said distribution cable buffering means.

40. A method of making a fiber optic cable assembly as described in claim 39, wherein said method further comprises the step of encapsulating said access point with a heat-recoverable patch.

41. A fiber optic cable assembly, comprising:

a slotted core distribution cable having a predetermined length and having first and second ends, said distribution cable further having a branch point being positioned along the length thereof, said distribution cable including;

a longitudinally extending slotted core central strength member having at least one groove therealong and having a length substantially equal to said predetermined length and having first and second ends, at least one optical fiber of substantially said predetermined length disposed within said groove, said fiber having first and second ends substantially coincident with the first and second ends of said distribution cable, and at least one branching optical fiber having first and second ends and having a first portion extending between its first end being coincident with said distribution cable first end and said branch point, said first portion being disposed within said groove and having a second portion extending between said branch point and its second end, said second portion being disposed outside of said groove and being continuous with said first portion; and

at least one branch cable having buffering means for encompassing said second portion of said branching optical fiber.

42. A method of making a fiber optic cable assembly utilizing a slotted core distribution cable having a predetermined length and having first and second ends, said distribution cable further having a branch point and a disconnect point each being positioned along the length of said distribution cable, said distribution cable including;

a longitudinally extending slotted core central strength member of said predetermined length having at least one groove therealong, at least one optical fiber of said predetermined length disposed within said groove, said optical fiber having first and second ends coincident with said first and second ends of said distribution cable, at least one branching optical fiber having first and second ends and having a first portion extending between the branching optical fiber first end being coincident with said distribution cable first end and said branch point and having a second portion extending between said branch point and the branching optical fiber second end being coincident with said disconnect point, said branching optical fiber being disposed within said groove, and outer jacketing means for encompassing said optical fibers and said central strength member, said method further utilizing at least one branch cable having buffering means, said method comprising steps of;

removing a portion of said outer jacketing means at said branch point so that said branching optical fiber is accessible;

removing said branching optical fiber second portion from within said outer jacketing means so that said branching optical fiber second portion is disposed outside of said outer jacketing means; and

configuring said branch cable buffering means so that it encompasses said branching optical fiber second portion.

43. A fiber optic cable assembly, comprising:

a distribution cable having a predetermined length, first and second ends and a branch point positioned along the length thereof, said distribution cable including, optical fiber guiding means having first and second ends, defining a length substantially equal to said predetermined length, at least one optical fiber of substantially said predetermined length disposed within said guiding means, said fiber having first and second ends of said distribution cable, and at least one branching optical fiber having first and second ends and having a first portion extending between its first end being coincident with said distribution cable first end and said branch point, said first portion being disposed within said guiding means and having a second portion extending between said branch point and its second end, said second portion being disposed outside of said guiding means and being continuous with said first portion; and

at least one branch cable having buffering means for encompassing said second portion of said branching optical fiber.