EP0076637A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical cable
Assignee: Nortel Networks Ltd
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Filing: 1982-09-29
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Granted: —
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Expires: 2002-09-29
Abstract
Abstract O In a known optical cable, optical fibers (24) are loosely laid in a number of grooves (16) formed within an elongate plastics extrusions (14). Typically the grooves (16) follow a helical path with periodically reversing pitch, the helices centered on a central longitudinal axis of the cable. A primary reason for the helical lay is to prevent the fibers (24) from becoming stressed should a bend occur in the cable. A further benefit of loose laying of fibers (24) in a helical groove (16) of periodically reversing pitch is that any elongation of the cable core is not immediately transmitted to the fiber (24) supported by it. The fiber (24) will move from its initial loose laid position both in a direction towards the inside curve (20) of the helix and in a direction towards the base (22) of the grooves (16). When it bears against the cable core over an appreciable length, the fiber (24) will then be subjected to tensile stress. By the invention, tolerance to core elongation is increased by arranging that the grooves (16) at any point along the core cant towards the outside curve (25) of the helix.
Inventors
- 👤 Masamichi Yataki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 18:41
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/44; G02B6/4479; G02B6/4489; B; B29; B29C; B29C48/00; B29C48/03; B29C48/12; G02B6/4401; G02B6/4407
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
92 words
An elongate extrusion for an optical cable, the extrusion having a periodically reversing helical compartment for housing at least one optical fiber, the compartment helix centered on a central axis of the extrusion, the compartment having side walls diverging radially outwardly from a base region thereof, characterised in that at any point along the extrusion, the side wall (20) on an inside curve of the helix is more nearly inclined to a radius extending through the base region (22) than is the side wall (25) on the outside curve of the helix.
Claim 2
Dependent Claim
92 words
An elongate extrusion for an optical cable, the extrusion having a periodically reversing helical compartment for housing at least one optical fiber, the compartment helix centered on a central axis of the extrusion, the compartment having side walls diverging radially outwardly from a base region thereof, characterised in that at any point along the extrusion, the side wall (20) on an inside curve of the helix is more nearly inclined to a radius extending through the base region (22) than is the side wall (25) on the outside curve of the helix.
Claim 3
Dependent Claim
102 words
An elongate extrusion for an optical cable, the extrusion having a periodically reversing helical compartment for housing at least one optical fiber, the compartment helix centered on an axis of the extrusion and having an outermost radial extremity and an innermost radial extremity, characterised in that the extremities are radially misaligned, the compartment helix having a pitch length, a pitch circle diameter, and a periodic pitch reversal such that on longitudinal elongation of the extrusion (14), a fiber (24) located within the compartment (26) and positioned at said outermost radial extremity tends to move in a direction towards said innermost radial extremity.
Claim 4
Dependent Claim
102 words
An elongate extrusion for an optical cable, the extrusion having a periodically reversing helical compartment for housing at least one optical fiber, the compartment helix centered on an axis of the extrusion and having an outermost radial extremity and an innermost radial extremity, characterised in that the extremities are radially misaligned, the compartment helix having a pitch length, a pitch circle diameter, and a periodic pitch reversal such that on longitudinal elongation of the extrusion (14), a fiber (24) located within the compartment (26) and positioned at said outermost radial extremity tends to move in a direction towards said innermost radial extremity.
Claim 5
Dependent Claim
25 words
An elongate extrusion according to claim 1 or 2 further characterised in that the extrusion (14) surrounds and keys to a central strength member (12).
Claim 6
Dependent Claim
18 words
An elongate extrusion as claimed in claim 1, further characterised in that the compartment (26) is a groove.
Claim 7
Dependent Claim
19 words
An elongate extrusion as claimed in claim 4, further characterised in that the groove (26) is of V section.
Claim 8
Dependent Claim
21 words
An elongate extrusion as claimed in claim 4, further characterised in that a base region of the groove (26) is angled.
Claim 9
Dependent Claim
21 words
An elongate extrusion as claimed in claim 4, further characterised in that a base region of the groove (26) is concave.
Claim 10
Dependent Claim
21 words
An elongate extrusion as claimed in claim 4, further characterised in that a base region of the groove (26) is convex.
Claim 11
Dependent Claim
23 words
An elongate extrusion as claimed in claim 1 or claim 2, further characterised in that the compartment (26) has a generally elliptical cross-section.
Claim 12
Dependent Claim
23 words
An elongate extrusion as claimed in any of the preceding claims, further characterised in that the extrusion (14) is generally annular in form.
Claim 13
Dependent Claim
22 words
An elongate extrusion as claimed in claim 1, further characterised in that the extrusion (14) has a plurality of such compartments (26).
Claim 14
Dependent Claim
24 words
An extrusion as claimed in claim 11, further characterised in that said compartments (26) are grooves in an outer surface of the extrusion (14).
Claim 15
Dependent Claim
103 words
Apparatus for making an elongate support member for an optical cable, the apparatus comprising extrusion means for extruding plastics through a die and forming means for forming a periodically reversing helical compartment in the extrusion, the helix followed by the compartment centered on a central axis of the extrusion, the apparatus characterised by adjustment means for alter the orientation of the compartment (26) relative to the central axis said forming means (40, 44) and said adjustment means (46, 52, 56) linked whereby to relate the compartment orientation at a particular point of the extrusion (14) to the helical pitch direction at that point.
Claim 16
Dependent Claim
103 words
Apparatus for making an elongate support member for an optical cable, the apparatus comprising extrusion means for extruding plastics through a die and forming means for forming a periodically reversing helical compartment in the extrusion, the helix followed by the compartment centered on a central axis of the extrusion, the apparatus characterised by adjustment means for alter the orientation of the compartment (26) relative to the central axis said forming means (40, 44) and said adjustment means (46, 52, 56) linked whereby to relate the compartment orientation at a particular point of the extrusion (14) to the helical pitch direction at that point.
Claim 17
Dependent Claim
102 words
Apparatus as claimed in claim 13, further characterised in that the die (44) is a fixed die and said forming means comprises a roller (46) downstream of the extrusion means (40, 44), which roller (46) bears against the extrusion (14) to form a groove (20, 22, 25) therein, the roller (46) mounted on a carriage (52, 56) rotatable about the cable axis, the roller (46) so mounted on the carriage (52, 56) as to permit a roller axis of rotation to be rocked back and forth whereby to relate orientation of the groove (20, 22, 25) to position on the reverse helix.
Claim 18
Dependent Claim
33 words
Apparatus as claimed in claim 14, further characterised in that the roller (46) is one of a plurality of identical rollers (46) mounted in circumferentially evenly spaced relationship about the extrusion central axis.
Claim 19
Dependent Claim
20 words
Apparatus as claimed in claim 15, further characterised in that the die (44) is fixed and has a circular aperture.
Claim 20
Dependent Claim
20 words
Apparatus as claimed in claim 15, further characterised in that the die (44) is fixed and has an annular aperture.
Claim 21
Dependent Claim
48 words
Apparatus as claimed in claim 13, further characterised in that a die forming part of the extrusion means has a plurality of fingers extending into a central aperture through the die, the fingers being oscillatable about an axis therethrough parallel to a central axis of the plastics extrusion.
Claim 22
Dependent Claim
15 words
Apparatus as claimed in claim 18, further characterised in rocker means to rock the fingers.
Claim 23
Dependent Claim
58 words
Apparatus as claimed in claim 19, further characterised in a twist means downstream of the extrusion means to grip the extrusion at a position remote from the die where the extruded material is relatively rigid, thereby to twist the extrusion and to introduce a reverse lay helical form to the grooves as the extruded plastics exits the die.
Claim 24
Dependent Claim
25 words
Apparatus as claimed in claim 20, further characterised by a drive to said twist means and a drive to said rocker means being mechanically linked.
Claim 25
Independent Claim
75 words
A method of manufacturing an elongate support member for an optical cable, the method comprising extruding plastics through a die, and forming a plurality of periodically reversing helical compartments in the plastics extrusion characterised in that at any point along the cable, orientation of such a compartment (26) relative to a central axis of the extrusion (14) is related to the pitch direction of the helical path followed by such compartment (26) at that point.
Claim 26
Independent Claim
75 words
A method of manufacturing an elongate support member for an optical cable, the method comprising extruding plastics through a die, and forming a plurality of periodically reversing helical compartments in the plastics extrusion characterised in that at any point along the cable, orientation of such a compartment (26) relative to a central axis of the extrusion (14) is related to the pitch direction of the helical path followed by such compartment (26) at that point.
References Cited (Backward Citations)
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