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US 4,141,623 AGranted
Optical fibre cable and a method of manufacture
AssigneeSociete Anonyme dite: Les Cables de Lyon
InventorsRene Dubost, Bernard Grenat
Life of this patent
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Abstract
A multiple optical fibre cable in which the fibres can be used separately for long distance signal transmission comprises a central core round which the optical conductors are concentically disposed. Each optical conductor is constituted by an optical fibre protected by a first layer or covering of polyamide and a second layer or sheath of polyethylene. In order to avoid distortion of the optical fibre, the second layer or sheath is stretched. Application: Optical telecommunications cables.
Claims8
A cable of optical fibers which can be used separately for signal transmission, said cable comprising:
- a central core;
- a bundle of optical fibers disposed concentrically around said core, said fibers having a diameter of about 100 microns and being covered with a first protective layer made of a first plastic material exhibiting a high modulus of elasticity and applied on the fiber with a clearance of a few microns;
- a second protective layer formed by extrusion of a second plastic material defining a tubular shaped protective layer formed about said first protective layer and having between them a clearance of a few tenths of a millimeter, said second plastic material having a lower melting point and a lower modulus of elasticity than that of said first plastic material;
- said optical fibers covered with their respective protective layers being assembled in concentric layers with longitudinal tension to exceed an elastic limit of said second plastic material while not that of said first material;
- such second protective layer being formed by extrusion at a temperature inhibiting softening of said first sheath;
- a sheath of an electrically conductive metal surrounding said outer concentric layer of optical fibers;
- and an outer sheath of plastic material.
4 more elements
Dependencies are inferred from the claim text.